Search

A large number of experimental studies have demonstrated that the permeability and damage of rock are not constant but rather functionally dependent on stresses or stress-induced deformation. Neglecting the influence of damage and permeability evolution on rock mechanics and sealing properties can result in an overestimation of the safety and stability of underground engineering, leading to an incomplete assessment of the risks associated with surrounding rock failure. To address this, the damage and permeability evolution functions of rock under compression were derived through a combination of experimental results and theoretical analysis, unifying the relationship between porosity and permeability in both porous media flow and fractured flow. Based on this, a fluid–solid coupled seepage model considering rock damage and permeability evolution was proposed. More importantly, this model was utilized to investigate the behavior of deformation, damage, and permeability, as well as their coupled effects. The model's validity was verified by comparing its numerical results with experimental data. The analysis results show that the evolution of permeability and porosity resulted from a competitive interaction between effective mean stress and stress-induced damage. When the effective mean stress was dominant, the permeability tended to decrease; otherwise, it followed an increasing trend. The damage evolution was primarily related to stress- and pressure-induced crack growth and irreversible deformation. Additionally, the influence of the seepage pressure on the strength, damage, and permeability of the investigated rock was evaluated. The model results reveal the damage and permeability evolution of the rock under compression, which has a certain guiding significance for the stability and safety analysis of rock in underground engineering. [ABSTRACT FROM AUTHOR]

Foundation treatment piles are crucial for enhancing the bearing capacity and stability of weak foundations and are widely utilized in construction projects. However, owing to the complexity of geological conditions, traditional construction methods fail to meet the demand for low-carbon development. To address these challenges, this study introduced a comprehensive decision-making approach that considers the impact of stratum variability on greenhouse gas (GHG) emissions and pile bearing capacity from the design phase. During the design process, the GHG emissions and bearing capacities of deep cement mixing (DCM) and high-pressure jet grouting (HPJG) piles were quantitatively assessed by analyzing the environmental and performance impacts of foundation treatment piles related to materials, transportation, and equipment usage. The results suggest that the bearing capacity of piles in shallow strata is highly susceptible to stratum variability. Using piles with a diameter of 800 mm and a length of 20 m as an example, compared with DCM piles, HPJG piles demonstrated a superior bearing capacity; however, their total GHG emissions were 6.58% higher, primarily because of the extensive use of machinery during HPJG pile construction. The GHG emissions of foundation treatment piles in shallow strata were influenced more by geological variability than those in deep strata. Sensitivity analysis revealed that the pile diameter is a critical determinant of GHG emissions and bearing capacity. Based on the bearing capacity–GHG emission optimization framework, a foundation treatment strategy that integrates overlapping and spaced pile arrangements was introduced. This innovative construction method reduced the total GHG emissions by 22.7% compared with conventional methods. These research findings contribute to low-carbon design in the construction industry. [ABSTRACT FROM AUTHOR]

Crack detection plays a critical role in ensuring road safety and maintenance. Traditional, manual, and semi-automatic detection methods have proven inefficient. Nowadays, the emergence of deep learning techniques has opened up new possibilities for automatic crack detection. However, there are few methods with both localization and segmentation abilities, and most perform poorly. The consistent nature of pavement over a small mileage range gives us the opportunity to make improvements. A novel data-augmentation strategy called CrackMover, specifically tailored for crack detection methods, is proposed. Experiments demonstrate the effectiveness of CrackMover for various methods. Moreover, this paper presents a new instance segmentation method for crack detection. It adopts a redesigned backbone network and incorporates a cascade structure for the region-based convolutional network (R-CNN) part. The experimental evaluation showcases significant performance improvements achieved by these approaches in crack detection. The proposed method achieves an average precision of 33.3%, surpassing Mask R-CNN with a Residual Network 50 backbone by 8.6%, proving its effectiveness in detecting crack distress. [ABSTRACT FROM AUTHOR]

The structural performance of shield tunnel structures is highly susceptible to degradation under complex environmental loads, with the most common manifestation being bolt preload loss. In this study, a shield tunnel numerical simulation model was established to analyze the seismic response of shield tunnels with varying degrees of bolt preload loss. Firstly, the deformation patterns of shield tunnel structures under seismic loads were analyzed. Subsequently, ellipticity and joint opening were selected as seismic resilience assessment indicators based on the mechanical response. A seismic resilience assessment model was then established, including three states: normal state, affected state, and recovered state. The results show a direct relationship between the recovery capacity of tunnel structures and the initial performance of the lining structure, as well as the magnitude of the load. The lower the degree of structure degradation, the greater the structural recovery capacity. Additionally, there is a positive correlation between residual deformation and the initial performance loss of shield tunnel structures, as well as the intensity of seismic loads. This study contributes to enriching the theoretical framework for the seismic resilience assessment of shield tunnels, which have significant implications and provide valuable references for engineering safety. [ABSTRACT FROM AUTHOR]

Shield tunnels can experience preload loss in their connecting bolts during the operational phase, leading to changes in tunnel structure stiffness, which, in turn, affect the seismic performance of shield tunnels. A refined three-dimensional model of shield tunnel was established using the finite element method to study the impact of preload loss in connecting bolts on the seismic dynamic response of shield tunnels. An artificial viscoelastic boundary was used to simulate the propagation of seismic waves from an infinitely distant field. This study investigated the effects of different levels of preload loss on the seismic response of shield tunnels. In addition, the Arias intensity, which can reflect the degree of seismic impact on structures, was used to analyse the extent of damage to the tunnel. The conclusions drawn from the study are as follows: As the level of preload loss increases, the tightness of the segments during the static phase gradually deteriorates, and the maximum joint opening during the seismic loading phase continues to increase. Post-earthquake non-recoverable ellipticity and radial deformation progressively increase with an increase to preload loss level. Overall tunnel damage becomes more significant with the degree of preload loss increases depending on the Arias intensity. Preload loss leads to a decrease in the overall structural stiffness and an increase in longitudinal relative displacement. In conclusion, preload loss also affects structural failure mode and seismic performance. These research findings are of reference value for enhancing the seismic performance of shield tunnel structures and ensuring engineering safety. [ABSTRACT FROM AUTHOR]

In recent times, there has been a sharp increase in the congestion of ground transportation, the scarcity of land resources, and various disasters. Hence, there is an urgent need to find an effective and sustainable approach to transportation. The construction of an underground logistics network, where transportation activities occur beneath the surface of the ground, is anticipated to emerge as a future trend. This study aims to formulate a resilient-maximizing plan for the underground logistics network, ensuring optimal meeting of transportation demands in the aftermath of ground disasters. Accordingly, a two-stage linear programming model is established to determine the layout plan for the most resilient underground logistics network. The first phase of the model is designed to generate viable layouts for the underground logistics network, while the second phase is dedicated to evaluating the resilience of the proposed layout plan. During the evaluation of network resilience, Monte Carlo simulations are used to simulate disaster scenarios. Given the inherent complexity of the model, the traditional solver cannot efficiently solve the problem. Thus, a new hybrid heuristic algorithm is designed to obtain solutions that maximize network resilience. The results show the effectiveness of the designed algorithm and the significant improvement in network resilience achieved by numerical experiments. Moreover, sensitivity analyses are conducted to reveal the relationships between resilience and budget, as well as resilience and the capacity of underground pipelines. It has a significant impact on sustainability when making decisions regarding network planning. [ABSTRACT FROM AUTHOR]

The degree of soil nonuniformity consolidation varies continuously with the passage of consolidation time and is accompanied by nonlinear alterations in soil parameters. Existing theoretical models often assume a constant relationship between the parameters of the two soil layers, failing to consider the effect of nonuniform consolidation. This assumption does not align with real-world conditions and can lead to significant errors in calculation results. Hence, this study aims to investigate the dynamic changes in soil undergoing nonuniform consolidation and develop a mathematical model that accounts for this phenomenon. Based on the large-strain and double-layer models, an improved consolidation model was proposed, which considers nonuniform variations in consolidation with a vertical drain and corrections to calculations under the influence of the nonlinear relationships of soil parameters. The proposed improved model was validated by comparison with field test data, and the results were compared with those of the classical model. Finally, the effects of different consolidation parameters on consolidation behavior were investigated. The research is a reliable calculation method that incorporates the dynamic nonuniform changes in consolidated soil, enabling more accurate predictions of consolidation of foundations treated by vertical drains. [ABSTRACT FROM AUTHOR]

Various adjacent construction projects are inevitably encountered during the large-scale construction of urban underground transportation. The case of a twin shield tunnel excavated below an existing multi-arch culvert bridge in close vicinity has not yet been thoroughly studied. A case of a shield tunnel excavation below an existing multi-arch culvert bridge in Foshan is presented. First, a fully coupled three-dimensional model incorporating fluid and solid interactions was established to simulate the twin shield tunnel excavation below the existing multi-arch culvert bridge in close vicinity. Subsequently, the numerical model was validated using the modified Peck empirical formula. Finally, the influence of different foundation reinforcement deformation moduli, tunnel excavation face support pressures and grouting pressures on ground deformation was discussed. The results indicate that the area most significantly affected by the excavation of the tunnel passing underneath is not within the section of the multi-arch culvert bridge after applying the foundation reinforcement design. The area most significantly impacted is concentrated as the shield tunnel commences excavation and advances beneath the location corresponding to the 1-hole of the steel corrugated pipe. The range of influence of the ground disturbance extends approximately 7 m in front of the excavation face before the tunnel passed through. The range of ground disturbance decreases to 4–6 m in front of the excavation face after the tunnel passed through. The excavation face support pressure and grouting pressure have a minor impact on the settlement of the multi-arch culvert bridge under this reinforcement design. The results provide useful references for the reinforcement design for tunnel excavation adjacent to existing structures. [ABSTRACT FROM AUTHOR]

The complex distribution of synchronous grouting pressure results in excessive tunnel deformation and various structural diseases, especially for ultra-large-diameter shield tunnels. In this study, to reduce the risk of tunnel failure, a three-dimensional refined finite element model was established for the Wuhan Lianghu highway tunnel project, taking into account the non-uniform distribution of synchronous grouting pressure. This study focuses on investigating the development patterns of internal forces, deformations, and damages in segment structures under varying grouting pressure ratios. The results indicate that the primary failure mode of a segment is tensile failure occurring at the outer edge of the arch. Moreover, an increased ratio of grouting pressure between the arch bottom and top leads to a higher positive bending moment value and greater tensile damage at the arch waist. The tunnel ring gradually exhibits distinct "horizontal duck egg" shape deformation. When the grouting pressure ratio is 2.8, there is a risk of tensile cracking at the outer edge of the arch waist. At this time, the segment convergence deformation is 39.71 mm, and the overall floating amount reaches 43.12 mm. This research offers engineering reference for the prediction of internal forces and deformations in ultra-large-diameter shield tunnels during grouting construction, thereby facilitating their application in the development of resilient cities. [ABSTRACT FROM AUTHOR]

The introduction of fibres into soil can effectively improve its engineering properties. Systematically understanding the unsaturated mechanical properties of fibre-reinforced soil is highly significant. Moreover, there is currently no suitable model for describing the water-retention characteristics of unsaturated fibre-reinforced soil. The purpose of this study is to propose a model for the soil–water characteristic curve (SWCC) that can accurately describe unsaturated fibre-reinforced soil. The research focuses on unsaturated sand reinforced with PP fibres. A series of compression and direct shear tests were performed to investigate the mechanical behaviour. In addition, the SWCC was measured using the axis-translation technique. Based on the van Genuchten (VG) model, a modified model considering fibre reinforcement (VG-CFR) is developed for quantitatively analysing the influence of fibre content on the SWCC. The results showed that the established VG-CFR model can reflect the water-retention characteristics of fibre-reinforced sand. [ABSTRACT FROM AUTHOR]

The Shenzhen Ma Wan area has special geotechnical conditions, with more than 50% of the area being reclaimed rock formations. Riprap reclamation strata are particularly susceptible to significant deformation upon stress release. To comprehensively comprehend the reaction of existing pipelines to the excavation of an adjacent deep foundation pit within the riprap reclamation strata, an interaction of the soil–pipeline was conducted by encompassing both scaled model tests and numerical simulations based on a cross-sea channel project. Firstly, scaled model tests were performed on a soil–pipeline interaction caused by excavation. Subsequently, the numerical model was verified by comparing the numerical simulation results with the scaled model test results. Then, the internal force, strain of the pipeline, and soil surface deformation under the conditions of a soil layer with riprap were analyzed, and the results were compared with the case without riprap. Finally, the influence of the support structures was analyzed. The results indicated that the presence of the riprap in strata led to a 19% increase in vertical displacement of the ground surface and a 35% increase in the pipeline bending moment compared with the case without riprap in the same strata. The maximum internal force and strain occurred at an inclined angle of 45° in the pipeline section. Furthermore, it was found that the first lateral support after excavation played a pivotal role in controlling the overall deformation of the foundation pit. The changes in stiffness in the lateral support were more sensitive to the horizontal displacement than the vertical displacement of the pipeline. The results provide valuable insights for the design and safety evaluation of engineering projects in riprap reclamation strata. [ABSTRACT FROM AUTHOR]

The arrangement of multiple culverts has gradually increased in road engineering. However, the arrangement will face a series of risks in both the construction and operation stages. A numerical model was established to analyze the construction and operation safety of multiple steel corrugated pipe arch culverts by using a fully fluid–solid coupling two-dimensional (2D) model of a highway project. The sensitivity of factors affecting the settlement of the composite foundation such as modulus and depth of ground reinforcement was discussed. Based on the results of the 2D model, a fully fluid–solid coupling three-dimensional (3D) model was established to study the influence of dynamic cyclic vehicle load on the mechanical properties of multiple steel corrugated pipe arch culverts. The ground deformation, soil stress and pore pressure, structure stress, and deformation were analyzed. The results show that the maximum settlement of the soil in the arch culvert area is at the junction of the two different arch culverts after construction. The maximum vertical deformation of the structure appears at the vault, and the arch waist is prone to stress concentration. Under cyclic vehicle dynamic load, the ground deformation, structural stress, and arch culvert subgrade deformation showed a rapid growth stage, and then tended to be stable. The weak points in the structure during the construction and operation stages were revealed, which can provide a useful reference for the design and construction of multiple steel corrugated pipe arch culverts. [ABSTRACT FROM AUTHOR]

The high-energy-level dynamic compaction method is widely used in various foundation treatment projects, but its reinforcement mechanism still lags behind the practice. In view of this, a three-dimensional fluid–solid coupling dynamic analysis model was established on the basis of the FDM–DEM coupling method. The variation trends of crater depth, soil void ratio, vertical additional dynamic stress, and pore water pressure during the process of dynamic compaction were analyzed. The results indicate that the curvature of the crater depth fitting curve gradually decreases with the increase in strike times, tending to a stable value. The initial particle structure is altered by the huge dynamic stress induced by dynamic compaction. As strike times increase, the soil void ratio decreases gradually. The vertical additional dynamic stress is the fundamental reason resulting in foundation compaction. Precipitation preloading before dynamic compaction can improve the reinforcement effect of dynamic compaction, making up for the deficiency that the vertical additional dynamic stress attenuates rapidly along the depth direction. The simulated CPT results illustrate that the modulus of foundation soil can be increased by 3–5 times after dynamic compaction. The research results can provide important reference for similar projects. [ABSTRACT FROM AUTHOR]

This study utilizes the enclosed and stable environment of underground space for long-term sustainable planning for urban epidemics and disasters. Owing to the COVID-19 epidemic, cities require long-term epidemic–disaster management. Therefore, this study proposed a strategy for integrating multiple functions to plan a comprehensive Underground Resilience Core (URC). A planning and assessment methods of URC were proposed. With this methodology, epidemic- and disaster- URCs were integrated to construct a comprehensive-URC in underground spaces. The results show: (1) Epidemic-resilient URCs adopting a joint progressive approach with designated hospitals can rapidly suppress an epidemic outbreak. (2) The regularity of the morphology of underground spaces determines the area of the URC. Bar-shaped underground spaces have the potential for planning disaster-URCs. (3) The URC planning efficiency ranking is as follows: Bar shapes lead overall, T shapes are second under seismic resilience, and Cross shapes are second under epidemic resilience. (4) The potential analysis of planning a comprehensive-URC in the underground parking in Chinese cities showed that the recovery time can be advanced from 29% to 39% and the comprehensive resilience can be improved by 37.63%. The results of this study can serve as sustainable urban planning strategies and assessment tools for long-term epidemic–disaster management. [ABSTRACT FROM AUTHOR]

Simple Summary: In this paper, we used scanning electron microscopy to describe the morphological types, number of sensilla, and their distributions on the antennae of each nymphal instar and adult of Notobitus meleagris (Hemiptera: Heteroptera: Coreidae). The results show that there were eight subtypes of sensilla on the antennae of the nymphs and 11 subtypes of sensilla on the antennae of the adults. With the growth of instars, the type, quantity, and size of the sensilla gradually increased. Sexual dimorphism did not appear in the type of sensilla but existed in the length and diameter of some sensilla. In addition, we also discussed the functions of different types of sensilla through previous published studies, which will be helpful for further research on the behavioral and biological control of N. meleagris. The bamboo bug Notobitus meleagris (Fabricius, 1787) is a serious pest of bamboo shoots in China, India, Myanmar, Vietnam, and Singapore. The antennae of the nymphal instars and adults of N.meleagris are involved in communication among individuals and finding the host plants. In order to understand the morphology of antennal sensilla, their types, and the distribution of sensilla on the antennae of nymphal instars and adults in N. meleagris, we studied the morphology of antennal sensilla with a scanning electron microscope. The antennae of the nymphs and adults comprised the scape, pedicel, and two flagellomeres. Four types and eight subtypes of sensilla were identified in the nymphal instars (sensilla trichodea [St].1, St.2, St.3, sensilla basiconica [Sb].1, Sb.2, sensilla chaetica [Sc].1, Sc.2, sensilla coeloconica [Sco].1), whereas those of the adults had five types and eleven subtypes of sensilla (St.1, St.2, St.3, Sb.1, Sb.2, Sb.3, Sc.1, Sc.2, Sco.1, Sco.2, and sensilla campaniformia [Sca]). There are significant differences in the number, type, and size of the sensilla in different nymphal instars, which increases with the increase in nymphal instars. There was no sexual dimorphism observed in the adult sensilla; however, the length and diameter of St.3, Sb.2, and Sb.3 were sexually dimorphic. The potential functions of each sensillum were discussed based on the morphology and distribution of the antennal sensilla and were compared with similar published studies. Our results provide primary data for further research on the behavioral mechanism, green prevention, and control of N. meleagris. [ABSTRACT FROM AUTHOR]

High-filled red soil typically lacks sufficient bearing capacity, which can pose significant challenges when constructing building foundations. One economical and effective method for the reinforcement of high-filled red soil is the dynamic compaction (DC) method. However, the design parameters for reinforcing high-filled red soil using the DC method are largely based on experience, which indicates the significant value of field results of related engineering practice. In this paper, we report a field study that was carried out to investigate the effect of impact energy on the treatment of super-high-filled ground with red soil in southwestern Yunnan, China, where three pilot DC tests were designed and conducted with three different impact energies (4000 kN·m, 8000 kN·m and 15,000 kN·m). To evaluate the reinforcement effect and optimize the DC operational parameters, a series of in situ tests, including settlement monitoring, standard penetration tests, dynamic penetration tests, surface wave velocity tests and plate-load tests, were carried out. Furthermore, the improvement depth of DC was discussed. The results of the field study show that the characteristic value of the ground bearing capacity of the three test zones could reach 250 kPa, which coincides with the design requirement, although the improvement depth of testing zone III fails to reach the required depth. This study helps to improve the in situ recycling of high-filled soil, thereby promoting the sustainable development of engineering construction. [ABSTRACT FROM AUTHOR]

A new stiffened composite pipe pile was developed for improving the foundation of reclaimed ground in ocean engineering. To study the bearing capacity of the stiffened composite pipe pile group, a combination of field test and finite element method was used. Firstly, field tests were performed on the proposed single stiffened composite pipe pile. The single stiffened composite pipe pile model was verified by comparing the numerical simulation results with the field test results. The load transfer mechanism from the stiffened core to the cemented soil and the surrounding soil was clarified. Further, a 3D finite element model of the stiffened composite pipe pile group was established based on the single stiffened composite pipe pile model. Finally, the bearing capacity of the pile group and the stress distribution of each pile were analysed and the influence of the pile spacing on the pile bearing capacity was discussed. The results showed that the axial stress of both the side and corner piles decreased rapidly with an increase in the pile spacing, and the stress-bearing ratio decreased. The stress-bearing ratio of the central pile increases with an increase in pile spacing. The smaller the pile spacing, the larger the load proportion of the composite pile group and the larger the foundation settlement. The optimal design scheme was a composite pile with a 500 mm stiffened core diameter, 700 mm outer cemented soil diameter, and a spacing between piles of four times the cemented soil diameter (2.8 m) considering the group pile bearing capacity and the economic benefits of the project. These results provide a reference for the design and construction of stiffened composite piles for ground improvement projects. [ABSTRACT FROM AUTHOR]

The development and utilization of underground space is an effective way to make intensive use of resources, solve "big city disease" and achieve high-quality development. The expansion and renovation of underground space in a central urban area is likely to cause serious damage to surrounding structures. In this study, a deep foundation excavation for the reconstruction of an urban subway station in the Greater Bay Area was chosen for analysis using the finite element method. Different from common excavation engineering, the interaction between the three coupling factors of train dynamic load, foundation excavation, and viaduct pile foundation were analyzed. Six different cases were calculated considering different working conditions of excavation depth and train dynamic load. Soil was evaluated using modified Cam-Clay model. The physical parameters of the soil were determined through on-site and laboratory tests. The results were compared with monitoring data, and the accuracy of the finite element model was verified. The settlement and influence range of the soil, and displacement and internal forces of viaduct piles were analyzed. The maximum settlement of the soil occurred in the direction of the short side of the foundation pit. The maximum value was approximately 0.53 times the excavation depth. The settlement increased by approximately 49% when applying the train load. The dynamic load had an aggravating influence on the horizontal displacement of the top of the pile, with a maximum increase of 51%. Moreover, the dynamic load increased the negative bending moment of the viaduct piles. This study provides a reference for the design and construction of geotechnical engineering projects. [ABSTRACT FROM AUTHOR]

Herein, we report the mitochondrial genomic characteristics of three insect pests, Notobitus meleagris, Macropes harringtonae, and Homoeocerus bipunctatus, collected from bamboo plants in Guizhou Province, China. For the first time, the damaged conditions and life histories of M. harringtonae and H. bipunctatus are described in detail and digital photographs of all their life stages are provided. Simultaneously, the mitochondrial genome sequences of three bamboo pests were sequenced and analyzed. Idiocerus laurifoliae and Nilaparvata lugens were used as outgroups, and the phylogenetic trees were constructed. The mitochondrial genomes of the three bamboo pests contained 37 classical genes, including 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), 22 transfer RNAs (tRNAs), and a control region, with a total length of 16,199 bp, 15,314 bp, and 16,706 bp, respectively. The A+T values of the three bamboo pests were similar, and trnS1 was a cloverleaf structure with missing arms. The phylogenetic analyses, using the Bayesian inference (BI) and Maximum likelihood (ML), supported that N. meleagris and H. bipunctatus belonged to the Coreoidea family, whereas M. harringtonae belonged to the Lygaeoidea family with high support values. This study involves the first complete sequencing of the mitochondrial genomes of two bamboo pests. By adding these newly sequenced mitochondrial genome data and detailed descriptions of life histories, the database of bamboo pests is improved. These data also provide information for the development of bamboo pest control methods by quick identification techniques and the use of detailed photographs. [ABSTRACT FROM AUTHOR]

A proper treatment of granite residual soil (GRS) in geotechnical practices requires both macro and microscopic evaluations. In this study, uniaxial and oedometric compression tests were conducted to investigate the mechanical properties of the saturated untreated and cement-treated GRS. Meanwhile, XRD, SEM, and MIP tests were conducted to identify the presence and types of C–S–H and the changes in the pore structure after cement treatment. The effects of cement treatment on the uniaxial compressive strength, secant modulus, compressibility, and vertical yielding pressure were revealed and the mechanisms of the soil structure to be modified through cement treatment were clarified based on the test results. A threshold volumetric cement content of 2–3% was determined based on the mechanical properties and microstructural characteristics of the saturated cement-treated GRS. Cement contents below this threshold would produce inadequate cementation between the soil particles. In contrast, cement contents above this threshold are considered inefficient because the transformation of the soil structure from single-porosity to dual-porosity increases the total porosity and retards the strength and stiffness gains. [ABSTRACT FROM AUTHOR]

Voids, a common defect in tunnel construction, lead to the deterioration of the lining structure and reduce the safety of tunnels. In this study, ground-penetrating radar (GPR) was used in tunnel lining void detection. Based on the finite difference time domain (FDTD) method, a forward model was established to simulate the process of tunnel lining void detection. The area of the forward image and the actual void area was analyzed based on the binarization method. Both the plain concrete and reinforced concrete lining with various sizes of air-filled and water-filled voids were considered. The rationality of the model was verified by measured data. It was observed that the response mode of voids can be hyperbolic, bowl-shaped, and strip-shaped, and this depends on the void's width. Compared with the air-filled voids, water filling increases the response range of the voids and produces a virtual image. Although the diffracted wave caused by a steel bar will bring about significant interference to the void response, the center position of the voids can be accurately located using 3D GPR. [ABSTRACT FROM AUTHOR]

Zinnia elegans Jacq. is an important, globally cultivated ornamental plant. In August 2021, a leaf spot disease was observed in zinnia in Shibing County, Guizhou, China, with an incidence of approximately 60%. Pathogens were isolated and purified from the infected leaves by tissue isolation, and pathogen strain BRJ2 was confirmed as the pathogen causing the leaf spot. Based on morphology and ITS, TEF-1α, and TUB2 sequence analyses, the pathogen was identified as Nigrospora musae (McLennan and Hoëtte). The mycelial growth rate method was used to determine the in vitro toxicity of five fungicides to the pathogen. The results showed that 10% difenoconazole provided the strongest inhibitory effect on N. musae, with a concentration for 50% of maximal effect (EC50) of 0.0658 mg/L; 75% trifloxystrobin·tebuconazole had the second greatest effect, with an EC50 of 0.1802 mg/L. This study provides the first report that N. musae caused leaf spot disease in Z. elegans and provides important guidance for the effective prevention and control of this disease in Guizhou. [ABSTRACT FROM AUTHOR]

There are significant energy and financial expenditures associated with the current thermal drainage consolidation approach used to treat the marine soft clay foundation. Especially for some reclaimed lands in remote areas where a large amount of stable electricity is not readily available. In view of the problem, this paper aims to investigate a novel treatment method by using solar energy thermal consolidation. The model testing was conducted to assess the treatment effect of the foundation. Results from two groups of one-dimensional surcharge preloading consolidation model experiments, conducted under conditions of both solar heating and ambient temperature, were presented. The advantage of the solar heating approach was demonstrated by a comparison of the two tests. An analytical calculation method was proposed for predicting the consolidation behavior on the basis of the temperature variation caused by solar energy in the marine soft clays, and good agreement was observed. The outcomes reveal that solar heating can improve the consolidation effect of soil deep in the foundation. The foundation temperature can be raised by 15 °C in winter, and the variation range can exceed 10 °C. The settlement increases by 16% compared with the ambient temperature group. [ABSTRACT FROM AUTHOR]

Shield tunnels are vulnerable to large displacements induced by surrounding environmental changes. Grouting is an effective way to correct excessive shield tunnel displacement, while the grouting scheme design, especially the grouting sequence, is the key factor affecting the correction efficiency. A finite element simulation method considering the construction of multiple grouting zones is verified by the engineering case of Shenzhen Metro Line 1, and the influence of the grouting sequence on the correction effect on the horizontal tunnel displacement is further studied. The results show that the proper grouting efficiency of sandy clay, completely decomposed granite, and strongly decomposed granite is 5.5%, 2.8%, and 1.1%, respectively. The adjacent newly-built grouting zones are significantly constrained by the reinforcement created during the preceding grouting process. It is more efficient to correct excessive tunnel displacement in the "from far to near" sequence and excessive tunnel convergence in the "from near to far" sequence with increasing reinforcement stiffness. The correction effect improves greatly as the elastic modulus of the reinforcement increases up to 100 MPa. [ABSTRACT FROM AUTHOR]

Being physical mechanical parameters of joints, normal and shear stiffnesses are indispensable components of the numerical simulation and theoretical analysis of the behavior of joints. The objective of this work is to put forward an experimental method to determine joint stiffness under constant normal load (CNL) conditions. For this purpose, joint closure and direct shear tests under CNL conditions were conducted. Normal stiffness was determined by the ratio of normal stress increment and the corresponding normal displacement; the shear stiffness was calculated by the ratio of shear stress increment to the relative shear displacement. The average and instantaneous shear stiffness were distinguished. Experimental results showed that joint normal and shear stiffness are time and spatially varying parameters during direct shearing. With increasing normal stress, average shear stiffness, maximum instantaneous shear stiffness, and normal stiffness increases. Normal stiffness was about 26–28 times higher than the average shear stiffness under one normal stress level. Average shear stiffness was little influenced by shear velocity. Instantaneous shear stiffness shows the velocity-dependent behavior. Maximum instantaneous shear stiffness decreases rapidly with increasing shear rate. At lower shear velocity, maximum instantaneous shear stiffness is higher than normal stiffness; minimum instantaneous shear stiffness can be negative and the absolute value also decreases with faster shear velocity. These findings provide a reference for selecting the appropriate value of normal and shear stiffness for evaluation of the mechanical response of interface. [ABSTRACT FROM AUTHOR]

To reduce or evaluate the damage of tunnels in seismically active areas when earthquakes happen, it is very important to quickly predict the tunnel damage. This study proposes an anti-entropy–fuzzy analytic hierarchy process (FAHP) combination weighting method for tunnel earthquake damage prediction. The tunnel cross section is a symmetrical structure. The method uses tunnel damage data from the tunnels in a region where earthquake disasters have occurred as sample data to calculate the standard earthquake damage index. The weights of evaluation factors are determined by combining the FAHP and anti-entropy weighting. The correction coefficient of each evaluation factor is obtained by considering the degree of each evaluation factor's influence on the average damage index. Then, the earthquake damage and the corresponding damage degree of each tunnel are obtained by weighting calculation. In this study, 55 tunnels in the Wenchuan earthquake-affected area are taken as analysis cases. In these cases, 45 cases of damage tunnels are used as sample data, and 10 random tunnels are used as training cases. The calculated results are compared with the observed results. The proposed method is confirmed simple and easy to implement, which can greatly reduce the workload of field investigation, calculation and analysis. The results is of great significance to the rapid earthquake emergency assessment and post earthquake recovery of tunnels. [ABSTRACT FROM AUTHOR]

Piles, which are always exposed to dynamic loads, are widely used in offshore structures. The dynamic response of the pile-soil-superstructure system in liquefiable soils is complicated, and the interaction between the pile and soil and the pile volume effect are the key influencing factors. In this study, a water-soil fully coupled dynamic finite element-finite difference (FE-FD) method was used to numerically simulate the centrifuge shaking table (CST) test of a four-pile group in saturated sand soil. An interface contact model was proposed to simulate the pile-soil interaction, and a solid element was used to consider the volume effect of the pile. The acceleration responses of the soil and pile, settlement deformation, excess pore water pressure, and bending moment were examined. The results show that the bending moment response of the two piles parallel to the shaking direction show minor differences, while the two piles perpendicular to the shaking direction show almost the same distribution. The values of excess pore water pressure at the same depth but different azimuth angles around the pile are also different. The numerical simulation can accurately reproduce soil deformation and pile internal force during and after dynamic loading. [ABSTRACT FROM AUTHOR]

Simple Summary: Historically, researchers have suggested different resolutions of the basal relationships of the family Histeridae based on various datasets and methods of phylogenetic analysis. Phylogenetic analyses combining extant and fossil forms will doubtlessly shed further light on its early evolution. The present study describes the first fossil Anapleus species from mid-Cretaceous Kachin amber. This new discovery enriches the fossil record of histerid beetles and has important implications for efforts to understand their early evolutionary history. For the first time, an extant histerid genus Anapleus Horn, 1873 is described from a specimen found in mid-Cretaceous Kachin amber. Anapleus kachinensis sp. nov. Although the genus Anapleus has not been precisely defined by synapomorphies, the new species shares numerous features with extant species while differing in comparatively few external characteristics. Anapleus kachinensis represents the first record of an extant histerid genus from Cretaceous deposits and provides further evidence of the ancient origin of the genus. [ABSTRACT FROM AUTHOR]

Featured Application: This study extends the previous active earth pressure studies to include c-φ soil of limited width in a dense underground environment by considering the soil-wall interaction and the ground surface overload. For c-φ soil formation (cohesive soil) of limited width with ground surface overload behind a deep retaining structure, a modified active earth pressure calculation model is established in this study. And three key issues are addressed through improved soil arching effect. First, the soil-wall interaction mechanism is determined by considering the soil arching effect. The slip surface of a limited soil is proved to be a double-fold line passing through the retaining wall toe and intersecting the side wall of the existing underground structure until it reaches the ground surface along the existing side wall. Second, the limited width boundary is explicated. And third, the variation in the active earth pressure from parameters of limited c-φ soil is determined. The lateral active earth pressure coefficient is nonlinear distributed based on the improved soil arching effect of the symmetric catenary curve. Furthermore, the active earth pressure distribution, the tension crack at the top of the retaining wall and the resultant force and its action point were obtained. By comparing with the existing analytical methods, such as the Rankine method, it demonstrates that the model proposed in this study is much closer to the measured and numerical results. Ignoring the influence of soil cohesion and the limited width will exponentially reduce the overall stability of the retaining structure and increase the risk of accidents. [ABSTRACT FROM AUTHOR]

A linear theoretical model is established for the dynamics of a hanging vertical cantilevered pipe which is subjected concurrently to internal and reverse external axial flows. Such pipe systems may have instability by flutter (amplified oscillations) or static divergence (buckling). The pipe system under consideration is a slender flexible cantilevered pipe hanging concentrically within an inflexible external pipe of larger diameter. From the clamped end to the free end, fluid is injected through the annular passage between the external pipe and the cantilevered pipe. When exiting the annular passage, the fluid discharges in the counter direction along the cantilevered pipe. The inflexible external pipe has a variable length and it can cover a portion of the length of the cantilevered pipe. This pipe system has been applied in the solution mining and in the salt cavern underground energy storage industry. The planar motion equation of the system is solved by means of a Galerkin method, and Euler–Bernoulli beam eigenfunctions are used as comparison functions. Calculations are conducted to quantify the effects of different confinement conditions (i.e., the radial confinement degree of the annular passage and the confined-flow length) on the cantilevered pipe stability, for a long leaching-tubing-like system. For a long system, an increase in the radial confinement degree of the annular passage and the confined-flow length gives rise to a series of flutter and divergence. Additionally, the effect of the cantilevered pipe length is studied. Increasing the cantilevered pipe length results in an increase of the critical flow velocity while a decrease of the associated critical frequency. For a long enough system, the critical frequency almost disappears. [ABSTRACT FROM AUTHOR]

The adverse effects of a hostile marine environment on concrete structures inevitably result in great economic loss and may contribute to catastrophic failure. There is limited information on the durability of concrete in a tensile stress-chloride ion-carbon dioxide (TCC) multiple-corrosion environment. The objective of this study is to explore the impact of a TCC multiple-corrosion environment on concrete considering three coupled factors of compressive strength, Cl− penetration, and carbonation. Dry–wet cycle tests were conducted to determine the strength degradation and Cl− penetration concentration of concrete in a hostile multiple-corrosion marine environment. The results show that the effects of water-soluble chloride ions (Cl−), carbon dioxide (CO2), and tensile stress on concrete are not a simple superposition, but involve obvious interaction. The compressive strength of a concrete specimen first increases and then decreases in chlorine salt-carbon tests. The Cl− concentration and tensile stress affect the carbonation depth of concrete, which increases with an increase in Cl− concentration, and with the application of tensile stress. The Cl− concentration has an obvious effect on the carbonation depth. In addition to experimental observations, a stepwise regression equation was established based on the multiple linear regression theory. A correlation analysis considering different factors was conducted to reflect the corrosion results more directly. [ABSTRACT FROM AUTHOR]

Gonatopus flavifemur (Esaki & Hashimoto) is a common parasitoid of the most important rice pest, the brown planthopper (BPH) Nilaparvata lugens (Stål), in eastern and southeastern Asia. We investigated the parasitism rates, feeding rates, and offspring development of G. flavifemur in association with five instars of BPH nymphs and male and female adults under laboratory conditions (27 ± 1 °C and 70 ± 5% Relative Humidity). The results showed that the life stage of the host significantly affects parasitism, host feeding, and offspring development by G. flavifemur. The parasitism rate was highest on 4th instar nymphs, and the feeding rate was highest on 1st instar nymphs. The cocooning rate on male adult BPHs was significantly lower than that on other stages; however, emergence rates did not significantly differ among the BPH stages. The rate of female offspring upon emergence from 5th instars was higher than other stages. Both the parasitism and host-feeding functional responses of G. flavifemur to different BPH stages fit well with Holling type II models, supporting the results of parasitism and feeding rates and indicating that G. flavifemur would be a good agent for BPH control. In conclusion, G. flavifemur prefers to feed on young nymphs but prefers to parasitize older nymphs. In addition, 5th instar nymphs are favorable to female offspring of the pincer wasp. [ABSTRACT FROM AUTHOR]

The huge energy consumption of metro operations has become a significant challenge faced by the urban public transportation sector to achieve low-carbon development. Using Shenzhen as an example, this study has made efforts to quantify the metro's energy consumption and carbon emission intensity during the operation phase by using the Life Cycle Assessment approach. Furthermore, this study evaluates the actions that can be taken to reduce energy consumption and emissions. A comparative analysis between metros and other public transportation modes has also been conducted. The results show that the annual carbon emissions from the metro's operation phase in Shenzhen city increased from 63,000 t CO 2 e in 2005 to 1.3 Mt CO 2 e in 2021, and the historically accumulated carbon emissions are 9.5 Mt CO 2 e. The unit operating mileage, the unit station area, and the per capita carbon emission intensity were 2.1 kg CO 2 e/km, 132.5 kg CO 2 e/m 2 , and 0.6 kg CO 2 e per capita (13th Five-Year Plan Period), respectively. By continually promoting the low-carbon operation of the subway, the cumulative carbon savings could reach 0.1 Mt CO 2 e (2022-2035).