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On January 7, 2022, a Mw 6.6 earthquake occurred in Menyuan County, Qinghai Province, China. To understand the coseismic deformation mechanism of this earthquake, we utilized GNSS and InSAR geodetic observations to obtain the coseismic deformation field and inverted for the slip distributions of different fault models. Through a comparative analysis of the coseismic slip distribution characteristics of different fault models and fitting degree of observations, we proposed the relatively optimal fault model. The coseismic deformation results of two types of observations consistently show a dominant horizontal strike-slip motion for this earthquake. The deformation characteristics of the coseismic LOS displacement profile model, considering the fault dip angle and slip amount, indicate that the coseismic slip is concentrated in the shallow portion, with a maximum slip of 3.29 m at a depth of 1.31 km. The inversion results of the optimal fault model proposed in this study indicate that compared to the surface trace of the Lenglongling fault, the surface trace of the eastern section of the primary fault is deflected by 9.28°, with a length of approximately 14 km, and the western section extends westward approximately 9 km along the Lenglongling fault. In the strike-change area between the Lenglongling fault and the Tuolaishan fault, the secondary fault connects the primary fault and extends westward along the Tuolaishan fault for approximately 8 km. The primary fault corresponds to the Lenglongling fault, with a maximum slip of 4.28 m, and the secondary fault corresponds to the Tuolaishan fault, with a maximum slip of 2.44 m. [ABSTRACT FROM AUTHOR]

The tectonic deformation of the southeastern margin of the Tibetan Plateau underwent significant changes before and after the Miocene, which led to the change of the deformation characteristics of the Sichuan‐Yunnan block, and some local areas in the block also showed structural patterns inconsistent with the macroscopic clockwise rotation deformation. Moreover, the Chenghai fault (CF) in the Sichuan‐Yunnan block was the seismogenic fault of the M 73/4 Yongsheng earthquake in 1515. However, the dense vegetation impeded the acquisition of surface deformation characteristics and small‐scale horizontal offsets along the fault, resulting in its misty kinematic properties, roughly determined geometric distribution, and the highly controversial rupture parameters of the Yongsheng earthquake. Therefore, we used airborne light detection and ranging, which can penetrate vegetation to obtain high‐resolution surface topography, to map the CF within 120 km. Combined with satellite images and field investigations, we determined that the CF consists of a series of secondary faults with simple geometric structures. Continuous offset linear landforms were preserved along the fault. 102 offsets below 30 m were statistically analyzed and the result revealed that the CF has a characteristic displacement of ∼6 m and it may rupture as a united rupture segment in each large earthquake or its two rupture segments cascade rupture to generate large earthquakes. The magnitude of the Yongsheng earthquake in 1515 was estimated at 7.7. Finally, based on this study, the kinematic characteristics of the Dali terrane and Sichuan‐Yunnan block, where the CF is located are discussed. Key Points: We obtained the fine geometry of the Chenghai fault (CF) and determined its kinematic propertyWe reestimated the magnitude of the Yongsheng earthquake in 1515We discussed the seismogenic pattern of the CF and kinematic characteristics of the Dali terrane and Sichuan‐Yunnan block [ABSTRACT FROM AUTHOR]

The red stratum soft rock, contained extensively in the deep soil–rock mixture (SRM) backfill area of southwest China, exhibits significant water-disintegrating properties that greatly impact the foundation's bearing capacity and deformation failure in this region. This study introduced the large-scale triaxial test to investigate the mechanical deformation characteristics of clay-red stratum soft rock mixture before and after wetting. Simultaneous, combined with the results of test, the law of water disintegration of red stratum soft rock was revealed, and its effects were analyzed in detail. The results show that: (1) Wetting intensified the crushing of rock blocks, resulting in the reduction of shear strength and critical strain of the samples, the decrease of critical internal friction angle and secant modulus, and the significant increase of the relative crushing rate of rock blocks; (2) The most significant increase and decrease of the content before and after the test occur in the particles with the particle size of 0.5–2 mm and 20–40 mm, respectively; (3) Wetting-induced breakage of the red stratum soft rock mainly occurs during the first two hours after encountering water; (4) An increase in confining pressure exacerbates the influence of wetting. Additionally, based on the theory of non-linear elasticity, with the assuming that the reduction of secant modulus causes the wetting deformation, a theoretical calculation model of the wetting axial strain was proposed. Through comparing the calculated results with the measured values obtained by using the "double-line method" and "single-line method" test, it is found that the calculation method can accurately predict the wetting axial strain of SRM and be used for quantitative analysis of wetting deformation. [ABSTRACT FROM AUTHOR]

The Tongbai complex plays an important role in the understanding of the tectonic evolution of the Tongbai‐Dabie orogenic belt. By detailed structural analysis, new zircon U–Pb dating, zircon Lu–Hf analysis and whole‐rock elements for the rocks in the Tongbai complex and the wrapped shear zones, we suggested that the Tongbai complex was derived from the partial melting of the basement of Yangtze Block and experienced a uniform orogen‐parallel extension with a top‐to‐NW shearing at 142–133 Ma. The migmatites yield a migmatization age of 116 ± 2 Ma and are identical to the metamorphic age of 115–111 Ma from the L and LS tectonites in the Tongbai complex. The late Early Cretaceous migmatization may give rise to the severance of the uniform top‐to‐NW shear zone and lead to an antiform folding of the Tongbai complex. The similar deformation and migmatization of the complexes in both the Tongbai and Dabie orogenic belts suggest that the Tongbai‐Dabie orogenic belt is likely to have a similar tectonic transformation from orogen‐parallel to orogen‐perpendicular extension in the Early Cretaceous, namely a uniform orogen‐parallel extension of the ductile lithosphere during the early Early Cretaceous and a widespread migmatization during the late Early Cretaceous. [ABSTRACT FROM AUTHOR]

Time series dynamic prediction of surface deformation in mining areas can provide reference data for coal mine safety and production, which has important impacts. The combination of interferometric synthetic aperture radar (InSAR) technology and the probability integral method (PIM) is commonly used for predicting deformation. However, most surface subsidence prediction in mining areas is based on the static PIM parameters, failing to achieve the three-dimensional (3D) dynamic deformation prediction. This paper proposed a 3D deformation dynamic prediction model (InSAR-3D-CTPIM) between InSAR deformation observations and dynamic coordinate-time PIM (CTPIM) parameters, which can realize the prediction of east–west, north–south, and vertical series deformation caused by mining. The method has been validated by simulation experiments and real experiments in the mining area of Jiansheng Coal Mine in Baisha Reservoir, Henan Province, China. The results showed that the modeling accuracy was improved by 34.3% compared to the traditional multi-rate model, and the accuracy was improved by 28.5% compared to the vertical deformation obtained by the traditional static PIM method. The InSAR-3D-CTPIM model can be used to predict the evolutionary history of basin-wide surface deformation dynamics in coal mining areas, and provide a reference for the early warning and prediction of geological hazards in coal mining areas. [ABSTRACT FROM AUTHOR]

With the gradual densification of China's railway network, more and more railways are inevitably crossing active fault zones. Creep dislocation and stick–slip dislocation of the fault zones can lead to uneven deformation and cracks in the railway subgrade, threatening the sustainability of the railway. Therefore, a model test and numerical simulation were used to analyze the deformation mechanism and sustainability of the subgrade and foundation induced by a strike–slip fault dislocation in a flat site under different angles between the subgrade and fault strikes. The test and simulation results show that (1) under the influence of strike–slip fault dislocation, the horizontal direction of the subgrade appeared to have an S–shaped displacement. The top surface of the subgrade appeared to have a vertical settlement. Further, tension–shear cracks and compression crush zones appeared on the subgrade's surface. (2) When the angle between the fault and subgrade strikes increased, the subgrade's uneven deformations induced by fault dislocation first decreased and then increased. The angle between the main tension–shear crack on the top surface of the subgrade and the fault strike showed a trend of increasing and then decreasing. In addition, the compressive stress along the subgrade strike decreased, while the tensile stress along the subgrade strike gradually increased. (3) The tension–shear cracks in the subgrade and foundation were spiral and converged to the basement strike–slip fault along the depth direction. This study provides a reference for the safe operation and sustainability of railways near faults. [ABSTRACT FROM AUTHOR]

The Weiningbeishan fold‐thrust belt (WFTB), located in the transitional zone of the Tibetan Plateau, Alxa Block and Ordos Basin, is an ancient intracontinental orogenic belt. In this article, structural analysis is conducted to more finely reveal differential deformation between the Devonian and Carboniferous strata in the WFTB. We found that the E–W‐trending open folds are mainly developed in the Upper Devonian Zhongning Formation (D3z), while the E–W‐trending close and tight folds are mainly developed in the Carboniferous strata. The N–S minimum shortening strain of the bottom boundary of Member 2 of the Upper Devonian Zhongning Formation (D3z2) is 21.1%, whereas the N–S minimum shortening strain of the bottom boundary of Member 2 of the Upper Carboniferous Danliangshan Formation (C2d2) is 64.1%. We propose that the E–W‐trending open folds in the Upper Devonian Zhongning Formation (D3z) and E–W‐trending close and tight folds in the Carboniferous strata were formed under the N–S compression during the Middle–Late Triassic. The Zhangyigou and Laoyagou faults are the main tear faults to accommodate differential displacement on the surface between the Upper Devonian Zhongning Formation (D3z) in the east and Carboniferous strata in the middle, which change into a décollement fault in the deep part of the Dafosigou fold area in the middle to accommodate differential deformation between the deep Upper Devonian Zhongning Formation (D3z) and Carboniferous strata. This study enables us to better understand the Mesozoic intracontinental deformation in response to far‐field plate‐boundary convergence in NW China. [ABSTRACT FROM AUTHOR]

In the western and southwestern regions of China, under-construction and completed highspeed railway tunnels often suffer from elevated floor heave, which seriously threatens the construction progress and operational safety of the tunnels. This paper relies on the typical horizontally laminated carbonaceous shale stratum of the Xingshandong Tunnel to carry out a research on the mechanism of elevation of the base of the back arch. The model of the surrounding rock below the base of the elevated arch is simplified by applying the method of qualitative analysis by component testing and quantitative calculation by numerical simulation. The effects of different layer thicknesses, interlayer cohesion and material strength on the damage pattern of laminated rock masses are revealed, the causes of bottom bulging in horizontally laminated rock enclosures are analysed and corresponding bottom bulge control and disposal techniques are proposed. The results indicate: (1) The reduction in layer thickness reduces the ability of the laminated composite rock mass to resist deformation and damage, mainly manifested in the shortening of the elastic phase and the acceleration of the deformation rate; the reduction in the bond strength between layers destroys the integrity of the laminated composite rock mass, leading to the acceleration of the laminated rock mass into the single rock layer stress phase, but the effect on the deterioration of ultimate bearing capacity is not obvious;the reduction in the strength of the rock mass itself greatly reduces the load-bearing capacity of the laminated composite rock formation, causing the damage process to accelerate significantly and further deepening the extent and scope of the impact, which, combined with the numerical simulation results, further proves that the strength of the rock mass itself dominates the deformation and damage of the laminated rock mass. (3) The fatigue damage of train vibration, the weakening effect of groundwater aggregation and the long-term mechanical properties of the surrounding rock will all affect the stability of the elevation arch of the tunnel, and the order of deformation control effect is: deepening invert>base grouting>invert arch bolt. [ABSTRACT FROM AUTHOR]

Under the condition of weakly cemented soft rock in Western China, the surrounding rock deformation of gob-side entry is obvious, especially under the influence of fault, and the problem of surrounding rock control becomes increasingly prominent. To solve this issue, this paper firstly studied and obtained the evolution law of the ground pressure appearance of the gob-side entry in the fault area, then put forward the concept of surrounding rock control in the fault area of the gob-side entry, put forward a targeted pressure relief + increase preload + passive reinforcement parallel to the roadway surrounding rock strengthening control scheme, and carried out field applications. The results show that the roof subsidence and mining side heave of the roadway in the fault area increase significantly, accompanied by the characteristics of broken cables, the length of the broken cable is 0.2 m–0.6 m, and the breaking process is divided into multiple breaks. The stress evolution of gob-side entry in fault area presents a stage characteristic of "rapid growth-stable." The surrounding rock control effect is improved under the bolt cable high pre-tightening support, and the roadway deformation is effectively controlled under the pressure relief + active + passive support, with a good application effect. [ABSTRACT FROM AUTHOR]

Red-bed mudstone, prevalent in southwest China, poses a formidable challenge due to its hydrophilic clay minerals, resulting in expansion, deformation, and cracking upon exposure to moisture. This study addresses uplift deformation disasters in high-speed railways by employing a moisture diffusion-deformation-fracture coupling model based on the finite-discrete element method (FDEM). The model integrates the influence of cracks on moisture diffusion. The investigation into various excavation depths reveals a direct correlation between depth and the formation of tensile cracks at the bottom of the railway cutting. These cracks expedite moisture migration, significantly impacting the temporal and spatial evolution of the moisture field. Additionally, crack expansion dominates hygroscopic deformation, with the lateral coordinate of the crack zone determining peak vertical displacement. Furthermore, key factors influencing deformation in railway cuttings, including the swelling factor and initial moisture content at the bottom of the cutting, are explored. The number of tensile and shear cracks increases with greater excavation depth, particularly concerning shear cracks. Higher swelling factors and initial moisture contents result in an increased total number of cracks, predominantly shear cracks. Numerical calculations provide valuable insights, offering a scientific foundation and directional guidance for the precise prevention, control, prediction, and comprehensive treatment of mudstone-related issues in high-speed railways. [ABSTRACT FROM AUTHOR]

A large number of cases of tunnel bottom deformation occur in nearly horizontally layered strata. This article analyzes the common characteristics of such tunnel bottom deformation through case studies, and introduces the limitations and requirements for bottom designs for China's high-speed railway tunnels. The deformation mechanisms of the tunnel bottom were studied through the physical model experiment which revealed the interaction characteristics between the layered surrounding rock and the tunnel bottom structure. Through the numerical simulation study, the effect of different elevated arch curvatures on deformation of the tunnel bottom was investigated, and the effectiveness of elevation arch deepening in deformation control of the tunnel bottom was verified. The classified control countermeasures for deformation at the bottoms of the tunnels in nearly horizontally layered strata are provided [ABSTRACT FROM AUTHOR]

In offshore engineering, marine clays, which are widespread in the southeastern coastal areas of China, may be subjected to two-way cyclic stresses. To experimentally investigate the effects of the two-way cyclic stress with low-stress amplitude on the cyclic behavior of soft marine clay, a series of triaxial tests is performed on intact marine clay from Zhoushan covering various values of the cyclic stress ratio (CSR) and confining pressure (p′0). Several useful conclusions are inferred: First, the double-amplitude axial strain (εDA), dynamic axial modulus (E), and energy dissipation (W) increase with the CSR. Second, under the same CSR, the value of εDA is independent of p′0. The values of E and W increase with increasing p′0 during cyclic loadings, whereas the normalized modulus and normalized energy are independent of p′0. Third, an allowable CSR is proposed based on the strain behavior and energy concept. Based on the experimental results, two equations are established to predict the dynamic axial modulus and double-amplitude axial strain. [ABSTRACT FROM AUTHOR]

The long‐term cyclic gas injection and production mode of the gas storage will lead to accelerated deformation of the surrounding rock of the old cavity, and even the instability and failure of the cavity. Considering the geological conditions and cavity measurement data of the old cavity of the horizontal butted‐well in China, the deformation and failure characteristics of the long‐term cyclic injection‐production process of the surrounding rock of the old cavity under different internal pressure difference and injection‐production frequency are studied. The long‐term stability of the gas storage is predicted by six indexes: the deformation of surrounding rock, dilatancy safety factor, volume shrinkage rate, plastic zone volume, equivalent strain, and no tensile stress. The results show that with the increase of operation duration and cycle times, the deformation, volume shrinkage rate, and plastic zone volume of the surrounding rock gradually increase after the old cavity is reconstructed into the gas storage and the difference of results under different UGS and CAES gradually expands. The stability of the surrounding rock of the old cavity under the cycle action of CAES will be lower. The number of cycles has a limited impact on the stability of the surrounding rock of the old cavity, while the operation duration and injection‐production pressure are the main determinants of the stability of the surrounding rock of the old cavity. If the old cavity of the salt mine is reconstructed into CAES, the parameters such as the number of cycles, the operation duration, and the injection‐production pressure still need to be considered comprehensively. The research results can provide reference value for the reasonable design of the gas storage pressure range of the old cavity and the safety and stability evaluation of the surrounding rock. [ABSTRACT FROM AUTHOR]

In excavation engineering, most of the retaining structures are subjected to asymmetrical loads, including in asymmetrical excavation and asymmetrical overloading. However, a theoretical solution to, and deformation-controlling method for, this problem has remained elusive to date. In this work, a semianalytical solution for determining the deformation of retaining structures subjected to asymmetrical loads was derived based on the principle of minimum potential energy. The retaining structures were viewed as flexible, and the overall deformation of the retaining system was evaluated by our proposed theoretical model. This model was verified by comparing it with practical monitoring data. Subsequently, the theoretical solution was applied to analyze the stress and deformation characteristics under the conditions of asymmetrical excavation and asymmetrical overloading, which can be controlled to ensure the safety of a project. Finally, because of the requirement for a small amount of deformation in the foundation pit retaining piles, the earth pressure on the retaining piles is close to the static earth pressure. Reducing the length of the retaining pile on one side had a greater influence on the deformation on that side, but less of an influence on the other side. Thus, the proposed model can be used for optimizing the asymmetrical design of a retaining structure in order to balance the economy and safety of a project. Our design theory can be applied to a variety of engineering projects. A typical case is the Guangzhou Baiyun District Comprehensive Transportation Hub Project in China. The method was used to analyze the status of the subway foundation pit, offering a new design scheme to reduce the design length of the retaining piles, which resulted in great economic benefits in its practical application. The findings provided in this paper can be applied to the engineering of any long, narrow foundation pit that can be simplified into a two-dimensional plane–strain calculation model, being used to realize more accurate deformation control over the foundation pit envelope. The core of this calculation method is that it can accurately describe the magnitude of the earth pressure. The distribution of the earth pressure is worthy of further study. [ABSTRACT FROM AUTHOR]

In eastern Qinghai Province, China, landslides are a frequent hazard, yet their large-scale monitoring and assessment are under-researched. This study utilized 31 Sentinel-1A satellite images from January 4, 2020, to August 9, 2022, and applied the Small Baseline Subset Interferometry Synthetic Aperture Radar (SBAS-InSAR) method to quantify surface subsidence and infer landslide deformation rates in the Loess Plateau. We identified 491 hazardous landslides, with 14 posing significant risks to the Yellow River, major highways, and over 10,000 residents. The average line-of-sight (LOS) surface displacement rate was 118 mm/year, peaking at 298 mm. Satellite imagery revealed rapid and continuous landslide front activity. The landslides' uneven distribution aligns with the area's complex geology and environment, predominantly occurring on 20°–40° slopes with the Normalized Difference Vegetation Index values below 0.3, and aligning with nearby faults in the Hualong basin. Detailed analysis of 14 key landslides showed a marked correlation between landslide movement and monthly precipitation, offering new insights into landslide deformation mechanisms and driving factors. [ABSTRACT FROM AUTHOR]

In geotechnical engineering, a bedding slope often leads to geological disasters, particularly in the case of bedding-locked rock slopes. This study focuses on a typical bedding-locked rock slope in western Henan Province, China. The deformation and fault characteristics were examined through the development of laboratory analogue experiments which allowed for the analysis of the physical and mechanical properties of the rock slope when subjected to a load. The deformation and faulting mechanisms of the slope were studied through the application of different strength loads to the slope model, as well as through the combination of its physical properties. The deformation and fault process were then simulated through the application of numerical modeling. The results reveal that the upper part of the slope features a linear slip surface, while the lower part features a circular arc slip surface, resulting in "linear + circular arc" damage geometry and a relatively flat shear surface. Maximum and minimum lateral displacement occur around the top and the foot of the slope, respectively, leaving the intermediate values at the middle. The shear strength is greater at the locking section, with the highest value found at the foot of the slope, followed by the middle and the top. The evolution of slope deformation can be divided into three stages: the loose deformation stage at the slope top and back; the stage of crack development, extension, and interlayer misalignment; and the stage of complete through crack formation and complete instability damage of the slope. Thus, the process of the deformation and damage of a rocky slope under loading conditions can be described as follows: load-induced loosening and deformation at the top and back of the slope, crack development, expansion, and interlayer misalignment, as well as tension crack expansion at the foot of the slope. The latter can expand and intensify interlayer misalignment, leading to the destruction of the locking section and ultimately causing the destabilization of the entire slope. [ABSTRACT FROM AUTHOR]

Strip filling mining in a goaf is of great significance for solving the 'three under' coal-pressure and mining-area ecological environment problems in Central and Eastern China, but the disturbance characteristics of filling parameters on overlying rock are not clear at present. Taking the geological conditions of the CT30101 working face in Mahuangliang coal mine and the short-wall interval strip filling as a background, the strength parameters (cohesion and friction angle), deformation parameters (elastic modulus and Poisson's ratio), and structural parameters (strip width and spacing) of the filling body were selected as experimental factors, and the maximum settlement of the direct roof and the ground surface was taken as the evaluation index. The influence degree of each factor was quantitatively characterized via a variance analysis and an F test, and the main control factors of the strip filling overburden settlement were proposed. The roof and surface displacement, the stress evolution law of the filling body, and the shape change of the surrounding rock plastic zone under different levels of main control factors in the entire process of mining filling coupling were analyzed in detail. The results showed that the cohesion of the backfill had a highly significant impact on the direct roof settlement, the strip spacing and the friction angle of backfill had a significant impact on it, the cohesion of the backfill and the strip spacing had a certain impact on the surface settlement, and the two had a cross-coupling effect. In the process of mining and filling, the stress evolution of the filling body was extremely complex, and it finally presented a saddle shape that was high on both sides and low in the middle; the majority of the strata and the filling body primarily exhibited shear damage, with a small amount of tensile failure zones appearing only in the direct roof and mid-section of the filling body. The above conclusions have a certain guiding significance for the optimal design of strip filling in a goaf. [ABSTRACT FROM AUTHOR]

The Kepingtage fold-and-thrust belt in the southwestern Tian Shan in western China hosted the 2020 Mw 6.0 Jiashi earthquake with no apparent surface ruptures. The thrust nappe structure in this region is characterized by moderate-magnitude (Mw5.5-6.5) seismicity, but the seismogenic mechanisms and controlling factors remain under investigation. In this study, we utilized Sentinel-1A synthetic aperture radar satellite data to reconstruct the InSAR coseismic deformation field of the 2020 Jiashi earthquake. To address the limitation imposed by residual orbital phases during the interferometric measurement, we proposed a novel automatic method that combines ascending and descending track data with terrain features for orbit refinement. Eight comparative tests were conducted to prove the effectiveness of the proposed method. Subsequently, we inverted the jointly constrained deformation field after orbit correction to obtain the fault geometric parameters and slip distribution. Our results show that the 2020 Jiashi earthquake is characterized by right-lateral transpressive motion. The smooth interference fringes demonstrate spatially continuous surface uplift and subsidence without detectable coseismic surface ruptures, with a maximum uplift of ~0.08 m and a maximum subsidence of ~0.03 m, caused by the subsurface folding due to deep seismic rupture. This event is best fitted by a north-dipping fault plane with a depth of 4.2 km, a dip angle of 11.6°, and a strike of 276° beneath the Keping thrust fault. In terms of various geometric parameters of the fault, the inversion results of this study are generally similar to the focal mechanism solution provided by USGS (MWb), but are different from the focal mechanism solutions of other institutions and previous research results. Combined with the published geological investigations and seismic reflection surveys, we suggest that the seismogenic structure of the 2020 Jiashi earthquake is the lower ramp of the Keping thrust fault and the abrupt fault bend between the lower and upper ramp may limit the propagation of the coseismic rupture to the surface. The limited rupture of this event is dominated by the irregularities in fault geometry along strike and dip, as well as the lower rock strength of the cover above the detachment, which contribute to a deeper understanding of the seismic behavior in fold-and-thrust belts and the moderate-magnitude seismicity in the southwestern Tian Shan region. [ABSTRACT FROM AUTHOR]

The reactivation of coüuviai Landslides in reservoir banks poses a serious threat to the safety of hydropower projects and nearby towns. This study aims to research the morphological evolution of this type of landslides under the action of reservoir water and the impact of morphological evolution on landslide stability. The study focused on the Yulinerzu landslide, a large reactivated colluvial landslide in the Xiluodu Reservoir, China. Field surveys were conducted to analyze the geological structure of the landslide. In situ monitoring and surveys were used to obtain the deformation characteristics and morphological evolution of the landslide. A combined seepage-slope stability analysis was conducted to reveal the deformation mechanism. The results show that the reactivation of the Yulinerzu landslide is dominated by reservoir water fluctuations rather than rainfall. The underlying geological condition of the colluvial landslide is its hydrogeological structure, which causes the landslide to deform in a step-like manner during reservoir operation. With the accumulation of displacement and morphology evolution, the landslide displayed self-stabilizing characteristics. Therefore, in the stability analysis and risk assessment of large deformation landslides, it is essential to take into account not only the hydraulic effects of reservoir fluctuation but also the evolution of landslide morphology. [ABSTRACT FROM AUTHOR]

The Hurenbuqi Sag, located on the Bayinbaolige uplift in the northern Erlian Basin, is a secondary depression rich in oil. In order to study the influence on hydrocarbon accumulation of the Early Cretaceous structures in the southern Hurenbuqi Sag, the geological, drilling and geophysical data has been analyzed carefully to reveal the Early Cretaceous extensional structural characteristics, differential structural deformation characteristics, tectonic evolution process, and the hydrocarbon accumulation process. The study revealed that, extensional tectonic system is the mainly composition of Early Cretaceous structure, it has controlled the three main tectonic subsidence stages, early initial tectonic subsidence, middle rapid tectonic subsidence and late slow tectonic subsidence, of the southern Hurenbuqi Sag. During the tectonic evolution, the Early Cretaceous deformation obviously controlled the development of the source rocks and hydrocarbon accumulation. This study is of great significance for analyzing the enrichment regulations of hydrocarbon and guiding the next oil and gas exploration. [ABSTRACT FROM AUTHOR]

A 16-year surface macroscopic survey and global positioning system (GPS) monitoring of the Sanmendong landslide in the Three Gorges Reservoir Area of China demonstrated that the degree of deformation of the landslide correlated with rainfall and fluctuations in reservoir levels. In this study, the seepage field and stability coefficient of the Sanmendong landslide deformation were estimated under rainfall conditions, and fluctuations in the reservoir water level and their coupling effects were simulated and calculated. As the water level increased, the seepage force was directed toward the inside of the slope, creating conditions that bolstered landslide stability. However, when the reservoir water level drops or rainfall occurs, a seepage force is directed to the outside of the slope, hindering landslide stability. GPS monitoring data and the correlation between reservoir water-level fluctuations, rainfall, and landslide deformation were analyzed. The analysis revealed a positive correlation between rainfall and the displacement rate at monitoring point ZG361, with a high gray correlation degree (0.761). However, the correlation between the rate of fluctuating reservoir water levels and displacement rate at monitoring point ZG361 was insignificant. The stability calculation demonstrated that under normal Three Gorges Reservoir operation, a decrease in the water level decreased the stability coefficient by < 1%, whereas heavy rainfall decreased the stability coefficient by > 10%. The above results prove that rainfall is the primary driver governing the deformation of the Sanmendong landslide. [ABSTRACT FROM AUTHOR]

In recent years, numerous ancient landslides initially triggered by historic earthquakes on the eastern Tibetan Plateau have been reactivated by fault activity and heavy rainfall, causing severe human and economic losses. Previous studies have indicated that short-term heavy rainfall plays a crucial role in the reactivation of ancient landslides. However, the deformation behavior and reactivation mechanisms of seasonal rainfall-induced ancient landslides remain poorly understood. In this paper, taking the Dandu ancient landslide as an example, field investigations, ring shear experiments, and interferometric synthetic aperture radar (InSAR) deformation monitoring were performed. The cracks in the landslide, formed by fault creeping and seismic activity, provide pathways for rainwater infiltration, ultimately reducing the shear resistance of the slip zone and causing reactivation and deformation of the Dandu landslide. The deformation behavior of landslides is very responsive to seasonal rainfall, with sliding movements beginning to accelerate sharply during the rainy season and decelerating during the dry season. However, this response generally lags by several weeks, indicating that rainfall takes time to infiltrate into the slip zone. These research results could help us better understand the reactivation mechanism of ancient landslides triggered by seasonal rainfall. Furthermore, these findings explain why many slope failures take place in the dry season, which typically occurs approximately a month after the rainy season, rather than in the rainy season itself. [ABSTRACT FROM AUTHOR]

In this paper, for the engineering problem of tunnel deformation damage caused by a tunnel–landslide orthogonal system landslide in northwest China, based on similar theory, a variety of materials and their ratios were explored to make similar models according to the physical and mechanical parameters of the site engineering rock, indoor physical model tests were constructed, and monitoring techniques, such as speckle displacement strain measurement, strain acquisition, and pressure sensors, were used to test the macroscopic deformation characteristics; through the detailed analysis and law summary of the test macroscopic deformation characteristics, displacement, anchor cable axial force, and strain data, it was finally found that under the orthogonal system of tunnel and sliding surface, the damage form of tunnel lining is mainly compression damage and shear damage, and the cracks are mainly tension cracks, and the effect of tunnel primary lining on the surrounding rock support is extremely limited under the action of huge sliding force; combined with the analysis of the model deformation characteristics and the axial force curve of the anchor cable during loading, it was found that the axial force change curve is consistent with the NPR Newton force curve can be used to evaluate slope stability and predict the occurrence of landslide disasters. Highlights: This paper focuses on the tunnel and surrounding rock damage evolution characteristics under tunnel–landslide orthogonal and tunnel crossing sliding surface conditions. The evolution of displacement field, NPR anchor cable axial force, and strain field were revealed using indoor large similar physical model test. The mechanism of tunnel–landslide interaction within the slope and the deformation and damage characteristics of the tunnel surrounding rock were analyzed to reveal the slope deformation law under different loads. The stress change law of constant-resistance large deformation anchor cable (NPR anchor cable) is explored, and a landslide warning mechanism based on constant-resistance large deformation anchor cable is established. [ABSTRACT FROM AUTHOR]

Cofferdam is a key component of the containment system during the construction period. In order to ensure the quality and safety of underground open cut structure projects in China, and to strongly promote the development and progress of similar underground engineering cofferdam technology such as open cut lake tunnels, this paper takes the Jinji Lake tunnel cofferdam project as the basis, and conducts a study on the deformation law and stability state of PC combined method pile cofferdam support structure during the whole process of weir pumping construction combined with field monitoring analysis. The results show that: (1) with the continuous pumping and slope excavation, the overall structural deformation of the cofferdam tends to move more and more towards the inner side of the cofferdam; (2) during the construction process, the horizontal displacement values of the pile tops on the waterward and backward sides of the cofferdam do not differ much; and the maximum horizontal displacement value of the pile body on the waterward side does not differ much from the horizontal displacement value of the pile top, but on the backward side differs significantly. (3) During the pumping process in the weir, the maximum horizontal displacement of the piles on both sides of the weir basically appears near the bottom of the lake. The study reveals the asymmetric deformation law of the piles on both sides of the weir, which provides reference for similar projects of PC combined method pile cofferdam. [ABSTRACT FROM AUTHOR]

The Xiaomojiu landslide is a typical high-elevation, long-runout landslide located in the Jinsha River Corridor. In this study, sequential InSAR time-series estimation was used to calculate the line of sight (LOS) surface displacements with descending and ascending Sentinel-1 images, and it turned out that the cumulative LOS surface displacement of the landslide was up to −78.4 mm during the period from October 2017 to April 2021 with the maximum LOS surface displacement rate of −38.5 mm/year. The landslide body could be divided into five zones (A, B1, B2, B3, and C) according to its topographical characteristics together with the LOS surface displacement time series. Combining engineering geological characteristics, LOS cumulative surface displacements with site investigation suggest that the Xiaomojiu landslide is likely to be a precipitation-triggered ancient traction rock landslide at the accelerated deformation stage. A dynamic simulation of the Xiaomojiu landslide with the PFC3D software shows that it could take approximately 65 s for the Xiaomojiu landslide from start-up to acceleration to deceleration to build-up of a barrier lake, followed by a simulation from the barrier lake to outburst floods with the HEC-RAS software indicating that the maximum depth of the outburst floods could be 13.5 m (15%), 24.6 m (25%), 42.1 m (50%), and 50.3 m (75%) along Qinghai-Tibet Plateau Transportation Corridor (QTPTC). It is believed that the results of this study provide a reference for landslide prevention along the QTPTC and the Jinsha River. [ABSTRACT FROM AUTHOR]

The diaphragm wall is widely used in deep excavation engineering to guarantee the safety of the foundation pit and surrounding environment during excavation. An accurate prediction of the lateral deformation of the diaphragm wall is the basis of the design and optimization of the diaphragm wall structure. In this paper, we apply the third-order shear deformation plate theory to develop an analytical method for predicting the lateral deformation of the diaphragm wall to take into account the effects of shear stress distributed along the thickness direction on the lateral deformation. By using the Pb-2 Ritz method, combined with the minimum potential energy concept, the analytical solution for the deformation of the diaphragm wall is obtained under certain simplifications. Three types of boundary conditions for the bottom side of the diaphragm wall are considered to meet different geological conditions. The proposed method is verified by comparing the results predicted in this study with the monitoring data obtained from the practical pit engineering of Dinggong south road metro station of Metro Line 2 in Nanchang, Jiangxi province, China. Finally, the effects of the thickness and the embedded depth of the diaphragm wall and the lateral support patterns are analyzed, and the optimized design parameters for the diaphragm wall are also suggested. The proposed method can theoretically provide preliminary parameter optimization guidance for the design and construction of a diaphragm wall. [ABSTRACT FROM AUTHOR]

Deformation can effectively reflect the structural state of concrete dams and, thus, establishing na accurate concrete dam deformation prediction model is important for dam health monitoring and early warning strategies. To address the problem that the spatial coordinates introduced in the traditional multi-point deformation prediction model of dams not being able to accurately and efficiently reflect the spatial correlation of multiple-measuring points, a 2D-1D-CNN model is proposed which expresses the spatial correlation between each measuring point through spatial feature vectors, replacing the spatial coordinates in the traditional multi-point model. First, the spatial feature vector is extracted from the historical spatio-temporal panel series of deformation values of measuring points via a Two-Dimensional Convolutional Neural Network (2D-CNN); second, the vector is combined with the environmental impact factor of dam deformation to form the final input factor of fused spatial features; and, thirdly, this vector is combined with the environmental impact factors of dam deformation to form the final input factor of fused spatial features, and the non-linear linkage between the factors and the measured displacement values is constructed by the efficient feature processing capability of a One-Dimensional Convolutional Neural Network (1D-CNN) to obtain the prediction results. Finally, the actual monitoring data of a concrete dam in China are used as an example to verify the validity of the model. The results show that the proposed model outperforms the other models in most cases, respectively, which verifies the effectiveness of the proposed model in this paper. [ABSTRACT FROM AUTHOR]

Layered rocks are heterogeneous media composed of multiscale minerals with contrasting geomechanical properties. It remains unclear how the mechanical responses of constituent minerals among different adjacent layers vary in a microscale. Based on the grid nanoindentation tests assisted by high‐resolution scanning electron microscopy and energy‐dispersive spectroscopy techniques, we quantified the mechanical responses of various minerals in an interbedded sandstone‐mudstone core sample and provided visual mineralogies and indentation patterns of different adjacent layers. Results show that the Young's modulus, hardness, and elasticity index of quartz and dolomite decrease, whereas their fracture toughness and plastic work ratio increase from the sandstone layer to the mudstone layer. Quartz displays elastic‐dominated deformations in the sandstone layer whereas transforms into medium‐plastic deformations in the mudstone layer. The mean values of Young's modulus, hardness, and elasticity index of quartz in the sandstone layer are 1.28, 2.00, and 1.56 times higher than that in the mudstone layer, respectively. Dolomite and phyllosilicate minerals show prominently plastic‐dominated deformations in each layer. When an indenter encounters multiple minerals simultaneously, the mechanical responses are determined by the softer phases and irregular indent impressions are generated. Shear and radical cracks are prone to occur in the elastic‐dominated minerals, while chipping damage is induced in the plastic‐dominated minerals. This work provides new insights and fundamental understandings in geomechanical properties contrasts in multilayered rocks, and can facilitate the geomechanical modeling and upscaling schemes in multilayered formations. Plain Language Summary: Multilayered formations often consist of lithological layers with significant variations in geomechanical properties. In Ordos Basin, China, the multilayered formations not only contain a large amount of unconventional oil and gas resources, but also provide a potentially safe and economic trap for CO2 geological storage. The geomechanical contrast between layers generally controls the rock heterogeneity and fracture containment in layered rocks. However, the mechanical response of an individual layer such as the pure sandstone on layered rocks is difficult to quantify on core samples since the thinly interbedded layer is less prone to extract for the standard mechanical tests. Moreover, it is infeasible to interpret the geomechanical heterogeneity in microscale by well logging results restricted by its resolution. Hence, we used nanoindentation tests combined with scanning electron microscopy and energy‐dispersive spectroscopy techniques to explore the mechanical properties and deformation behaviors of the microsized minerals among adjacent layers including sandstone, mudstone, and their interfaces. This study is expected to provide direct visual insights into the mechanical responses and contrasts among various minerals in adjacent layers, and will possibly facilitate the rock‐physics modeling and upscaling, which can help to guide for the hydraulic fracturing designing, waste water injection, and CO2 injection for carbon capture and storage, etc. Key Points: Geomechanical responses of individual minerals and multiple minerals were quantified in different layers of an interbedded core sampleElasticity index of quartz and dolomite decreases whereas fracture toughness and plastic work ratio increase from sandstone to mudstoneMechanical responses of multiple minerals are determined by the softer phases, resulting in irregular indent impressions in each layer [ABSTRACT FROM AUTHOR]

Of major concern is the lack of correlation between the material design and structural function of asphalt pavement in China. The objective of this paper is to identify the layer in asphalt pavement where permanent deformation occurs most seriously and to propose a control index for that layer's asphalt mixture. The permanent deformation of each layer was determined through the utilization of thickness measurements obtained from field cores. The results indicate that the reduction in thickness is more significant in the driving lane than in the ridge band and shoulder. This phenomenon can be attributed to the intensified densification and shearing deformation that arise from the combined impacts of recurrent axle loads and high temperatures. Compared to surface and base layers, the bearing layer is the primary area of concern for permanent deformation in asphalt pavement. Therefore, it is imperative to incorporate the ability of bearing-layer asphalt mixture to withstand permanent deformation as a crucial design parameter. The dynamic modulus of the bearing-layer asphalt mixture is significantly influenced by the type of asphalt, gradation, and asphalt content, compared to other design parameters. Based on the relationship established between dynamic modulus and dynamic stability, with creep rate as the intermediate term, a control standard was proposed to evaluate the permanent deformation of the bearing-layer asphalt mixture. This study can provide reasonable and effective guidance for prolonging pavement life and improving pavement performance. [ABSTRACT FROM AUTHOR]

In response to the significant soft rock deformation challenges encountered during the construction of the Minxian Tunnel along the Lanzhou-Haikou Expressway (G75), this study conducted a comprehensive analysis of soft rock types and the underlying mechanical mechanisms governing the deformation of the surrounding rock. It presented tailored mechanical transformation strategies to address diverse mechanical mechanisms. Also, it introduced the application of anchor cable with high pre-tightening force, constant resistance and large deformation, a proven solution widely employed in mining and rock engineering. Furthermore, the research proposed a highprestress and active and passive combined support technique, encompassing pre-reinforced retaining structure, optimally arranged active retaining structure with long and short NPR anchor cables, steel arches, and permanent retaining structure of shotcrete. By implementing numerical simulations and on-site monitoring, the results demonstrated a remarkable reduction in the maximum deformation of the surrounding rock in the test section to only 73 mm, and the pre-tightening forces applied to the anchor cable with constant resistance and large deformation ranged from 280 to 300 kN, underscoring the effectiveness of the optimized retaining technique in controlling surrounding rock deformation. This research highlights the pivotal role of retaining structure with constant resistance and yielding support, which significantly improves deformation control. [ABSTRACT FROM AUTHOR]

The Nanwenhe metamorphic dome contains a rare Silurian granitic pluton that developed in the SE Yangtze Block during early Palaeozoic orogenesis, and this pluton comprises the Nanwenhe gneissic granites. The petrogenetic and structural deformation histories of the gneissic granites recorded the multi-stage interaction of the SE Yangtze Block with other blocks during the Palaeozoic and Mesozoic, including the Cathaysia, Indochina, and Paleo-Pacific blocks. Zircon U–Pb and Hf isotopes and geochemical data indicate that the Early Palaeozoic granites (433–420 Ma) are S-type granitic rocks, and they were derived from the partial melting of ancient continental crust with no contribution from mantle material. And the large variations and positive values of εHf(t) (−12.25 to +10.69) of the gneissic granites are ascribed to a heterogeneous source and disequilibrium melting. Here we compare early Palaeozoic granitoids in the SE Yangtze Block (foreland belt) with those in the orogenic core, and suggest that the SE Yangtze Block underwent limited syn-collisional crustal thickening and metamorphism, and following which post-collisional granitoids were formed through partial melting of continental crust. Structural analysis of the Nanwenhe gneissic granites allows two stages of deformation to be identified: northward detachment (D1) and northwestward thrusting (D2). 40Ar–39Ar isotope dating of muscovites from the gneissic granites yields a well-defined plateau age of 229.61 Ma, which is interpreted as the timing of Late Triassic structural overprinting associated with the formation of the Nanwenhe metamorphic dome. Integration of our new results with previous research findings from the dome and South China allows us to conclude that the detachment deformation (D1) represents Late Triassic post-collisional extension, and D2 represented Jurassic intracontinental orogeny associated with subduction of the Paleo-Pacific Block. [ABSTRACT FROM AUTHOR]

During the excavation of a water-conveyance tunnel in Tertiary soft rocks in China, significant deformation of the surrounding rocks and damage to the support were observed. Substantial horizontal deformation, reaching magnitudes of meters, was observed in the right side wall after a certain period of tunnel excavation. Extensive investigations, including field surveys, monitoring data analysis, laboratory tests, and numerical simulations, were conducted to understand the underlying mechanisms of this large deformation. The section of the tunnel with large deformation consisted of Tertiary sandy mudstone, mudstone interbedded with marl, and glutenite. Laboratory tests and mineral composition analysis revealed that the sandy mudstone and mudstone interbedded with marl exhibited low strength, which was closely related to the water content of the rock specimens. The compressive strength gradually decreased with increasing water content, and when the water content of mudstone interbedded with marl reached 26.96%, the uniaxial compressive strength decreased to only 0.24 MPa. Additionally, sandy mudstone and mudstone interbedded with marl contained a significant amount of hydrophilic minerals, with montmorillonite constituting 30% and 34% of the two rock samples, respectively. The tunnel passed beneath a perennially flowing gully, and a highly permeable glutenite layer was present in the middle of the tunnel. This resulted in groundwater seepage from the inverted arch during excavation, leading to the softening effect on the mudstone interbedded with marl in the lower part of the tunnel. Through numerical simulation and back-analysis techniques, the varying degrees of softening induced by groundwater were quantitatively analyzed in the surrounding rocks on the left and right sides. The study revealed that the large deformation of the tunnel was triggered by two factors: the plastic flow caused by tunnel excavation under the low strength of the surrounding rocks and the softening effect of groundwater. The damage to the support system was primarily attributed to the squeezing and swelling deformation of the surrounding rocks and the non-uniform deformation between different rock layers. [ABSTRACT FROM AUTHOR]

Ground deformation is the direct manifestation of the earth-rock dam's hazard potential. Therefore, it is essential to monitor deformation for dam warning and security evaluation. The Liuduzhai Dam, a clay-core dam of a large reservoir in China, was reinforced with plastic concrete cut-off walls between 13 January 2009 and 29 May 2010, as it was subject to leakage and deformation. However, the deformation development and the mechanism of the dam are still unclear. In this study, the deformation fields before and after the reinforcement of the Liuduzhai Dam were yielded by using the Interferometric Synthetic Aperture Radar (InSAR) technique. Furthermore, a numerical simulation method was employed to obtain the dynamic seepage field of the dam during the InSAR observation period. The results indicated that the average deformation velocity and maximum deformation velocity are −11.7 mm/yr and −22.5 mm/yr, respectively, and the cumulative displacement exceeds 100 mm, which shows typical continuous growth characteristics in a time series. In contrast, the dam deformation tended to be stable after reinforcement, with the average deformation velocity and maximum deformation velocity being −0.4 mm/yr and −1.2 mm/yr, respectively, behaving as cyclical deformation time series. According to the results of InSAR and seepage analysis, it is shown that: (1) dynamic seepage was the main mechanism controlling dam deformation prior to reinforcement; (2) the concentrated load caused by construction and the rapid dissipation of pore water pressure caused by the sudden drop of the infiltration line were the reasons for the acceleration of deformation during and after construction; and (3) the plastic concrete cut-off walls effectively reduced the dynamic seepage field, while the water level fluctuations were the main driving factor of elastic deformation of the dam after reinforcement. This study provides a novel approach to investigating the deformation mechanism of earth-rock dams. Furthermore, it has been confirmed that InSAR can identify the seepage deformation of dams by detecting surface movements. It is recommended that InSAR deformation monitoring should be incorporated into future dam safety programs to provide detailed deformation signals. By analyzing the temporal and spatial characteristics of the deformation signal, we can identify areas where dam performance has degraded. This crucial information aids in conducting a comprehensive dam safety assessment. [ABSTRACT FROM AUTHOR]

Whether deformation of exhumed crust in a collisional orogen is driven by buoyancy or tectonic stress remains uncertain. The Sulu orogen in eastern China contains slowly subducted and exhumed high-pressure (HP)--ultrahigh-pressure (UHP) terranes, which provide a good opportunity to understand whether the exhumation deformation was driven by buoyancy. We used field and microscopic observations as well as quartz c-axis fabrics to determine the deformation kinematics, temperatures, and evolution of the exhumed crustal slices. Deformed and undeformed dikes were dated by using the zircon U-Pb laser ablation--inductively coupled plasma--mass spectrometry method to constrain the timing of deformation. Our data demonstrate that each crustal slice was involved in pervasive top-to-the-NW (hinterland) or top-to-the-SE (foreland) ductile deformation during Late Triassic exhumation, and that the base of each slice records deformation that was superimposed during the subsequent exhumation of the underlying slice. The crustal exhumation of the southern Sulu orogen is consistent with the multistage ductile extrusion model. The kinematics of exhumation deformation within each crustal slice conform to an upward asymmetric flow. The flow velocity and corresponding shear sense were affected by temperature variations in each HP slice, whereas they were sensitive to migmatization within the UHP slices. The southern Sulu orogen examples show that crustal flow deformation during exhumation was driven by buoyancy and controlled by viscosity. Unlike the consistent kinematics of tectonics-driven deformation, the kinematics of buoyancy-driven deformation are characterized by variations in the senses of shear within a single crustal slice, and this can therefore be used to distinguish the two types of deformation. [ABSTRACT FROM AUTHOR]

In soft-soil areas, excessive transverse deformations have occurred in numerous shield tunnel linings accompanied by serious structural defects. However, to date, a method to effectively diagnose the health status of these poor-performing structures is unknown. This study focuses on health diagnosis for the typical stagger-joint-assembled shield tunnel linings in soft-soil areas of China. First, based on theoretical analyses, it is assumed that diametral deformation can be a significant indicator for the structural performance of a lining; subsequently, this is verified by abundant field data. In particular, a strong positive correlation between the diametral deformation and development of defects is observed. Subsequently, a full-scale test is performed to reveal further quantitative correlations. Besides the service limit values determined in the range of 0.24%–0.79% by specifications and prior studies, the test reveals detailed structural performance deterioration when the deformation is getting larger, where 1.5% is considered a threshold for the failure the entire structure. Additionally, the values of 0.5%, 0.8%, and 1.1% are observed to be key points indicating the gradual degradation of waterproofing, cracks, and overall mechanical performance of the lining. Based on these key points, a five-level health-degree model is constructed to determine the health status of a ring that can be regarded as a supplement of the previous limit values, which is more detailed and practical for the common large-deformed in-service linings in soft-soil areas. These findings can also serve as benchmarks for related studies on linings with different structural parameters in the future. [ABSTRACT FROM AUTHOR]

This study focuses on the deformation characteristics of Kadui-2 Landslide by the influence of reservoir filling-drawdown and precipitation. A three-year monitoring project was implemented in order to observe the short/long-term deformation. The slide mass experienced consistent deformation with a maximum cumulative displacement of 331.34 cm. Based on the recorded data of reservoir water level and precipitation during this period, a two-dimensional (2-D) finite element model using Geostudio software was set up for deformation simulation under different conditions to understand the real influence of these triggering factors on landslide. The numerical simulation results are in consistent with monitoring field data. Both numerical simulation and field monitoring results exhibit that the maximum deformation occurred at the foreside of slumping mass. The slip surface shows significant creep characteristics decreasing as long-term shear strength reducing gradually. Reservoir water level fluctuation is the primary triggering factor to reactivate the landslide mass and has a negative correlation with deformation rate. Displacement rate increases with the reservoir drawdown and decreases with impoundment rise. Compared with reservoir filling-drawdown operation, rainfall has no significant effect on the slide motion of landslide due to limited penetration from the ground surface. [ABSTRACT FROM AUTHOR]

The stability, design, and evaluation of coal-pillar dams are affected by how water and mining affect the mechanical performance and failure mode of coal. We analyzed the composition and water-absorption mechanisms of coal samples taken from the Chahasu coal mine in western China by x-ray diffraction and nondestructive water-soaking tests. Uniaxial compression tests were carried out on coal samples with different moisture contents and loading rates to investigate their mechanical properties and deformation damage characteristics while monitoring the acoustic emissions. The compressive strength and modulus of elasticity decreased with increased moisture content, with maximum attenuations of 50.3% and 42.4%, respectively. Increasing the loading rate caused the compressive strength and elastic modulus to first increase and then decrease; the maximum increases were 74.2% and 82.5%. With low moisture content and low loading rate, the coal samples become brittle; the main failure mode was tensile failure. Increasing the moisture content enhanced the plasticity of the coal samples, leading to more shear cracks and a switch in failure mode from tensile failure to shear failure. The increased loading rate reduces the effect of water on coal samples and increases the tensile effect. High loading rates tend to produce conical failure features. Acoustic emission characteristics were used as the basis for classifying the stress stages of coal samples, which further supplements the analysis of the failure process of coal samples. Finally, the reference of this study to field engineering practice and its own limitations were analyzed. These results should help guide the design of stable underground hydraulic systems and advance our understanding of rock-fracture-failure mechanisms in a water-rich environment. [ABSTRACT FROM AUTHOR]

Controlled by regional geological background, and affected by human activity and weathering, toppling deformation slopes occur in different regions in China. Based on statistics about domestic toppling deformation slopes and their distribution, the regional geological susceptibility zonation area of toppling deformation slopes was determined. Firstly, a regional geological susceptibility evaluation was conducted according to these toppling deformation slopes, choosing landform, stratigraphic age, seismic intensity and tectonic stress distribution, and the study area was divided into very low, low, medium, high and very high susceptibility areas. Secondly, a geographic position susceptibility evaluation was conducted aimed at different sections of typical rivers in western China and the toppling deformation slopes related to them, and the study area was divided into upstream, midstream and downstream of 11 rivers that were respectively classified into very low, low, high and very high susceptibility areas. Thirdly, based on the results, associations between the toppling deformation factors (lithology, slope height, elevation, horizontal depth and vertical depth) and the distribution of deformation slopes were revealed. Finally, the development regularity was analyzed comprehensively. The results show that the toppling deformation slopes of hydropower projects are more developed in Sichuan, Qinghai and Yunnan provinces of China. With regard to regional geography, besides the Yellow River, both the Lancang River and the Yalong River flow through areas with toppling deformation that are classified as highly susceptible geological zones in all levels. The results of this study can be used as references for site selection plans in hydropower projects. [ABSTRACT FROM AUTHOR]

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On February 26, 2021, the ancient Moli landslide in Guoye town, Zhouqu County, Gansu Province, China, was reactivated. The volume of the reactivated landslide was approximately 2120 × 104 m3, which was classified as a remote accumulation layer landslide in a deep superlarge fault fracture zone. No casualties occurred due to timely warnings. The deformation characteristics and failure mechanisms of the landslide were systematically studied by means of field investigations and engineering mapping, field exploration, deep displacement monitoring, and high-density electrical methods. We found that the geological structure and landform of Zhouqu County are extremely complex. The sliding mass of this landslide was mainly gravelly soil with poor soil mechanical properties. The gravelly clay and phyllite clastic layers were prone to sliding. The landslide as a whole presented the comprehensive characteristics of front edge erosion traction and rear load displacement and was associated with multiple secondary landslides. The Heisongping–Sanjiaoping fault zone of the Bailong River passes through the rear edge of the landslide, and a variety of inducing factors worked together to make the landslide failure mechanism particularly complex. The monitoring and comprehensive control of this kind of landslide should be strengthened. [ABSTRACT FROM AUTHOR]

During the reservoir filling of many high arch dams, it was observed that the valley slopes on both sides deformed towards the river. The measured value of valley narrowing lateral deformation (VNLD) reached 89.54 mm by October 2018. This rare phenomenon contradicts the traditional experience of dam engineering and lacks a convincing explanation. An arch dam project in China is selected as a case study to analyze the mechanism of the VNLD. Based on a comprehensive analysis of the geological background and the VNLD measurements, a numerical study is performed to identify the main factors that may contribute to the VNLD phenomenon. It is concluded that the time-dependent valley deformation is due to the rheological behaviour of rock mass with the change of hydrogeological conditions. The artesian water head in the deep-confined aquifer is increased and the mechanical parameters in fault and shear zones are weakened after reservoir filling, which is associated with the specific hydrogeological structures. The rise of artesian water head is the main induced factor that contributes to the uplift deformation, which is observed at the dam site, and can cause the VNLD in the horizontal direction. The simulated results considering these factors agreed well with the observed data. [ABSTRACT FROM AUTHOR]

During the operational period, unexpected upstream deformation has been observed in several super-high arch dams located in the alpine and gorge regions. In addition, the phenomenon of the downstream dam deformation monitoring values being apparently smaller than the numerical simulation results appears in some super-high arch dams. This paper focuses on the genetic mechanism of a super-high arch dam's special deformation characteristics. The finite element method (FEM) was used to analyze the effects of solar radiation, valley contraction, and overhanging on super-high arch dam's deformation behavior. First, the influences of solar radiation on the temperature field and deformation characteristics of the super-high arch dam under the shading effects of the mountain and the dam body were investigated. Second, the impacts of valley contraction on the deformation characteristics of the super-high arch dam during the storage period were studied. Subsequently, the impact of the overhanging effect on the super-high arch dam's deformation was explored. Finally, a case study was conducted on the basis of the Jinping I super-high arch dam to evaluate the effectiveness of the proposed analytical method. It is indicated that the dam's special deformation can be explained reasonably. Above all, in order to accurately analyze and predict the deformation characteristics of super high-arch dams in the alpine and gorge regions of Southwest China, solar radiation, valley contraction, and the dam-overhanging effect need to be considered as influencing factors of dam deformation. [ABSTRACT FROM AUTHOR]

Health monitoring is important for densely distributed urban infrastructures, particularly in cities undergoing rapid economic progress. Permanent scatterer interferometry (PSI) is an advanced remote sensing observation technique that is commonly used in urban infrastructure monitoring. However, the rapid construction of infrastructures may easily cause a loss of coherence for radar interferometry, inducing a low density of effective permanent scatterer (PS) points, which is the main limitation of PSI. In order to address these problems, a novel time-series synthetic aperture radar interferometry (InSAR) process based on the adaptive window homogeneous pixel selection and phase optimization (AWHPSPO) algorithm and thermal expansion linear model (TELM) is proposed. Firstly, for homogeneous point selection, information on both the time-series intensity and deformation phases is considered, which can compensate for the defects of insufficient homogeneous samples and low phase quality in traditional distributed scatterer interferometric synthetic aperture radar (DS-InSAR) processing. Secondly, the physical, thermal expansion component, which reflects the material properties of the infrastructures, is introduced into the traditional linear model, which can more rationally reflect the temporal evolution of deformation variation, and the thermal expansion coefficients can be estimated simultaneously with the deformation parameters. In order to verify our proposed algorithm, the Orange Island area in Changsha City, China, was selected as the study area in this experiment. Three years of its historical time-series deformation fields and thermal expansion coefficients were regenerated. With the use of high-resolution TerraSAR-X radar satellite images, a maximum accumulated settlement of 12.3 mm and a minor uplift of 8.2 mm were detected. Crossvalidation with small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) results using Sentinel 1A data proved the reliability of AWHPSPO. The proposed algorithm can provide a reference for the control of the health and safety of urban infrastructures. [ABSTRACT FROM AUTHOR]

The multi-row stabilizing piles have been applied in the stabilization of large-scale reservoir landslides in recent years. However, the mechanical behavior and deformation characteristics of the multi-row stabilizing piles reinforced reservoir landslides have rarely been investigated. This study takes the Taping landslide, a large-scale reservoir landslide in China, as a prototype. Two centrifuge tests were conducted to study the deformation and failure characteristics of the multi-row stabilizing piles reinforced reservoir landslide with two different row spacings. The result shows that the reservoir water level (RWL) drawdown operation induced the soil movement and high downslope driving force, further causing a significant increase in bending moments at the lower section of the piles, with peaking near the sliding zone; eventually, bending deformation and failure occurred more easily near the sliding zone. The downslope part of the piles can change the mechanical transmission behavior of the multi-row stabilizing piles in reservoir landslides. Small row spacing can enhance the mechanical connection between the rows of piles and raise the overall reinforcement capacity of the piles. The large row spacing weakens the mechanical connection between the rows of piles, and the mechanical states of the pile in different rows are relatively independent. As a result, the piles are easily damaged one by one from the first row to the last row, and the overall reinforcement capacity of the multi-row stabilizing piles is poor. [ABSTRACT FROM AUTHOR]

The deformation characteristic of the arch dam can directly reflect its service performance, which can be analyzed on the basis of the dam deformation field. However, restricted by the limited number of dam monitoring points and the inhomogeneity of materials, an accurate measurement of arch dam deformation field is difficult to estimate by using the existing common methods, such as the spatial interpolation methods and the finite element method (FEM). With the aim of ensuring arch dam structure safety, the ordinary kriging interpolation method, combined with FEM, is proposed for arch dam deformation field estimation, in this study. Given the inversion of the computation parameters of the arch dam, FEM is used to calculate the basic arch dam deformation. Subsequently, the ordinary kriging interpolation method is introduced to estimate the spatial variance deformation at each point of the arch dam. One superhigh arch dam in China is selected as a case study; two additional methods are introduced as comparisons that are based on a numerical experiment and the actual monitoring data. The experimental results show that the proposed method considerably improves the accuracy and computational efficiency of the arch dam deformation field estimation and that it is of great practical importance for characterizing the deformation behavior of arch dams. [ABSTRACT FROM AUTHOR]

The Bayanwula Tectonic Belt (BTB) is located between the Alxa Massif and the Ordos Basin in the northwestern North China Craton (NCC). The Mid‐Mesozoic to Cenozoic deformation characteristics of the BTB is crucial for understanding the tectonic processes of eastern Asia during that time. Together with the regional geology, our field observation and structural analysis reveal that the BTB has undergone three phases of deformation since the Late Jurassic. The first phase of deformation (D1) is represented by NE–SW‐striking thrust faults involved in the Jurassic strata, indicating a phase of NW–SE shortening deformation. Based on the combination of angular unconformity between the Upper Jurassic and Lower Cretaceous strata, the timing of D1 is constrained at the end of Jurassic and dynamically related to the westward subduction of the Palaeo‐Pacific Plate during the end of the Jurassic. The second one (D2) is characterized by the ~NE–SW‐striking normal faults and Lower Cretaceous syn‐sedimentary strata on both sides of the BTB, which show that a phase of ~NW–SE extension deformation occurred in the Early Cretaceous, dynamically related to the rollback of the Palaeo‐Pacific Plate in the Early Cretaceous. The third stage of deformation (D3) is represented by the NW–SE‐striking folds that involved the Pliocene strata, as well as dextral strike‐slipping of the East Bayanwula Fault and the West Helanshan Fault, indicating a phase of NE–SW shortening at the end of the Pliocene. Dynamically, the D3 is related to the outward expansion of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

The Nandongzi landslide occurred in the Yanshan region of North China. From 2017, the slope of the Nandongzi landslide has been significantly deformed after several excavations. Field investigations show that the Nandongzi landslide is a special toppling deposit that does not have basic toppling conditions. The toppling deformation mechanism of the slope has become a difficult issue for engineers, attracting the attention of scientists. Joint, surface, and borehole lithology surveys revealed the surface and internal structural characteristics of the slope. The structure of the soft and hard interbedded rock and the proximity of the fault are the dominant factors of slope toppling deformation. The slope toppling failure process can be divided into four stages: initial deformation, compression and bending, toppling and overlapping, and reactivation. In the first three stages, slope toppling deformation is triggered by the downcutting of the upstream gully, gravity, and differential weathering of soft and hard rocks, which promote the dumping deformation of the slope. In the final stage, engineering excavations triggered the reactivation of residual deposits. Monitoring data indicate that slope deformation is directly related to rainfall events. Flac 3D was used to simulate the slope failure process under natural and rainfall conditions after the two excavations. The results show that multiple excavations changed the surface and runoff conditions of the slope, which led to slope failure. Rainfall promoted deformation of the back edge of the landslide, which led to shear failure from the back edge to the front edge. Our results provide new and unique understanding into the spatiotemporal evolution and deformation mechanism of similar toppling-accumulation landslides around the study area. [ABSTRACT FROM AUTHOR]

The Lashagou landslide group in Gansu Province, China, is a typical shallow loess landslide group caused by artificial slope cutting. In April 2018, local sliding of the landslide group damaged houses and blocked the G310 highway, leading to the relocation of the Lashagou village, which aroused widespread concern. Unfortunately, the spatiotemporal displacement characteristics and failure modes of the landslide remain unknown. In this study, a method for the estimation of two-dimensional deformation of landslides, based on the local parallel flow model, was presented. This method only needs two orbital synthetic aperture radar (SAR) images with different imaging geometries, and has high accuracy verified by global satellite navigation system (GNSS) observations. In practice, we first obtained the surface velocity and time series deformation of the ascending and descending orbits. The best-fit sliding direction and inclination of the landslide movement were then inverted by combining satellite imaging geometry and surface velocity. Furthermore, the two-dimensional deformation of the Lashagou landslide group in the sliding and normal directions was obtained. We found that the landslide was in the accelerated deformation stage during the wet season and the deformation was mainly concentrated in the northern part of the Lashagou village. The snowmelt and continuous rainfall were the main factors in the landslide deformation. In addition, the landslide surface displacement characteristics and deep stress states can be linked using a combination of two-dimensional deformation, combined deformation, and inclination, which provides evidence that landslide movement is controlled by one or more deep continuous structural planes. Our research shows that the two-dimensional deformation retrieval method can be applied to gravity-driven translational landslides to help prevent and mitigate landslide hazards. [ABSTRACT FROM AUTHOR]

The Jiaju ancient landslide is a giant landslide located upstream of the Dadu River, eastern Tibetan Plateau, with a volume of approx. 7.04 × 108 m3. The Jiaju ancient landslide is complex and comprises five secondary sliding bodies, e.g., the Jiaju landslide (H01), Niexiaping landslide (H02), Xiaobawang landslide (H03), Niela landslide (H04), and Mt.-peak landslide (H05). Affected by regional neotectonic movement, heavy rainfall, river erosion, and lithology, the secondary sliding bodies of the Jiaju ancient landslide are undergoing significantly different creep-sliding deformation, which will cause great damage to villages, roads, and rivers around the sliding bodies. Combined with the SBAS-InSAR method, Sentinel-1A data from June 2018 to August 2021, remote sensing and field surveys, this study obtained the Jiaju ancient landslide deformation characteristics and deformation rate in the line-of-sight direction (VLOS), slope (VSlope), and vertical (VVertical). It is concluded that the maximum deformation rate of the Jiaju ancient landslide is significant. The maximum of VLOS, VSlope, and VVertical are −179 mm/a, −211 mm/a, and −67 mm/a, respectively. The Niela landslide (H04), Jiaju landslide (H01), and Mt.-peak landslide (H05) are very large and suffer strong deformation. Among these, the Niela landslide (H04) is in the accelerative deformation stage and at the Warn warning level, and the Jiaju landslide (H01) is in the creep deformation and attention warning level, especially heavy rainfall, which will accelerate landslide deformation and trigger reactivation. Because the geological structure is very complex for the Jiaju ancient landslide and strong neotectonic movement, under heavy rainfall, the secondary landslide creep-sliding rate of the Jiaju ancient landslide is easily accelerated and finally slides in part or as a whole, resulting in river blocking. It is suggested to strengthen the landslide deformation monitoring of the Niela landslide and Jiaju landslide and provide disaster mitigation and prevention support to the government and residents along the Dadu River watershed. [ABSTRACT FROM AUTHOR]