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In this paper, the deformation response of the stratum in the vicinity of a tunnel is investigated based on a case study in Tianjin. A method to predict the surface settlement in the case of double-track curvature shield tunneling is also proposed. The research methodology consists of analytical calculations, finite element analysis as well as field monitoring. Straight shield tunneling and curvature shield tunneling are modeled, each with a single-track shield and a double-track shield, and their operational parameters are compared. The influence of overcutting and existing tunnel on ground movement is also discussed. The salient observations from the series of analyses are as follows: (a) The maximum settlement induced by curvature shield tunneling is much greater than that induced by straight shield tunneling, while the existing tunnel has little impact on stratum settlement in contrast, (b) the proposed method of predicting the surface settlement induced by double-track curvature shield tunneling fits well with the field-monitored data in the Tianjin case study, and (c) the location of the maximum ground settlement is deviated by the overcutting phenomenon, whereas the settlement of the soil above the excavated tunnel is reduced due to the presence of the existing tunnel. [ABSTRACT FROM AUTHOR]

The prevailing design methodology for foundation pit support structures conventionally treats the pit cross section as a two-dimensional plane, facilitating the computation of soil and water pressures acting upon the retaining structure. Regrettably, this conventional approach tends to overlook the critical corner effect, particularly when the foundation pit is in proximity to a subway tunnel, where the nuanced nature of this corner effect remains indeterminate. Consequently, this research is directed toward an in-depth investigation of a deep foundation pit contiguous to a subway tunnel. A systematic evaluation and optimization of the corner effect pertaining to the deep foundation pit are undertaken through a combination of comprehensive field monitoring and simulation methodologies. The results show that a substantial mitigation in the deformation of the supporting structure, settlements of the ground surface and adjacent buildings, as well as the displacement of the subway tunnel, were achieved through a consideration of the corner effect. Notably, the ameliorative impact of adjacent buildings on the corner effect is observed. Further scrutiny reveals that the supporting structure within a distance of 12 m from the pit corner is most susceptible to the corner effect, as evidenced by a plane strain ratio (PSR) falling below 0.8. Beyond a spatial threshold of 20 m, the PSR attains a value of 1.0, indicative of a negligible corner effect and the foundation pit section existing in a plane strain state. The adjustment of pile length or diameter based on the PSR emerges as a viable strategy that can realize the construction cost optimization on the premise of ensuring the stability of the foundation pit. The impact of pile diameter variation is paramount, corresponding to a reduction in the range of PSR values below 0.8 from 12 m to 9.8 m. The corner effect is significantly diminished. [ABSTRACT FROM AUTHOR]

Due to the complexity of construction sequence and the extended duration required to construct super large section tunnels, the selection of excavation method critically influences the stability of the surrounding rock and support structures. In this work, the Xiaoyuan Tunnel project in Jiangxi Province serves as the research background for employing ABAQUS software to simulate the variations in displacement and stress within the rock and support structures under three different excavation methods. The simulated results are subsequently compared and verified against monitoring data. The findings indicate that the three-benching seven-step method releases more stress (maximum principal stress value reaches 0.621 MPa) from the surrounding rock and support structures than the other methods, resulting in stress concentrations. Therefore, it is of vital significance to complete the initial support in time and seal the tunnel opening quickly. The maximum principal stress values caused by three excavation methods all appear at the arch foot position, highlighting the need for prompt reinforcement of stability support there. Compared to the CRD method and the three-benching seven-step method, the tunnel vault's settlement value caused by the double-side drift method is reduced by 14% and 19%, respectively. Furthermore, the largest disturbance of the surrounding rock occurs under the CRD method, while the double-side drift method minimizes such disturbances, making it the preferred choice for the construction of super large section tunnels. These insights are invaluable for guiding the selection and optimization of construction methods for such tunnels. [ABSTRACT FROM AUTHOR]

The inverted arch heaving is detrimental to the structural safety of tunnels and can cause operational accidents. It is necessary to perform the research on maintenance strategies of inverted arch heaving to ensure the structural safety of tunnels. This paper took the Sanlian Tunnel in Southwest China as the engineering background, and the goals of this research were to explore the cause and maintenance of the inverted arch heaving in tuff stratum. The research methodology in this paper includes numerical simulation and field observations. Proposing maintenance measures for inverted arch heaving in tuff formation and grasping the long-term stress characteristics of the inverted arch structure are the contributions of this study. The inverted arch distress includes heaving (85 mm), cracks, and flexural deformation of reinforcements. FLAC3D numerical simulation shows that the continuous deformation because of the tuff rheological effect has an adverse impact on the inverted arch structure, resulting in cracking and heaving. Deepened inverted arch structure by 65 cm combined with 8 m-long prestressed anchor rods were adopted to control the distress. The effectiveness of the maintenance approach was assessed through field observations lasting for three years. Influenced by the long-term rheology of the tuff, the stresses in the inverted arch increased rapidly at first, then slowly, and gradually stabilized two years after the construction was completed. The maximum stress of prestressed anchor rods, steel arch frames, initial support concrete, and secondary lining concrete were 84.53 MPa, 22.40 MPa, 13.35 MPa, 7.20MP, respectively, which were less than the allowable stress (namely 210 MPa, 160 MPa, 23.8 MPa, 32.5 MPa, respectively). Furthermore, the minimum safety factor (namely 6.75) of the reinforced inverted arch met the requirements (>2.4) specified by the Code for Design of Railway Tunnel. The reported findings validate the overall safety of the inverted arch structure following the implementation of control measures, demonstrating the efficacy of these measures in effectively addressing the identified issues. The proposed maintenance strategies and revealed long-term stress characteristics of inverted arch structure in this work can be referenced for construction of tunnels in tuff formation. [ABSTRACT FROM AUTHOR]

A large-scale foundation pit with an area of 39,677 m2 (B2) was excavated to the south of an existing 25,720 m2 Chengdu Universal Trade Plaza (CDUTP) foundation pit (B1) in Chengdu, China. The purpose of this manuscript was to investigate the deformation characteristics of B2 and compare the difference of deformation characteristics between foundation pits B1 and B2. Direct monitoring results of foundation pit B2 were comprehensively investigated and compared with that observed in B1, which include lateral movement, column movement, stress in the columns, and axis force in the anchor cable. Additionally, a strategic approach to mitigate potential extensive lateral deformation was introduced. The monitored results for B2 revealed that the deflection and vertical movement of the columns were comparatively smaller than the reported lower boundaries. The maximum excavation-induced lateral column deflection exhibited a notable 35% reduction in comparison to the lateral deflection observed in the new excavation. However, vertical column movements were approximately twice as pronounced as those in B1. Furthermore, the installation of temporary columns with anchor cables in front of permanent columns proved effective in limiting the vertical deformation during excavation in close proximity to the permanent columns. This research provides valuable insights into the documentation of large-size excavations in soft soil, along with corresponding mitigation approaches. [ABSTRACT FROM AUTHOR]

The performance of asymmetric pit-in-pit excavation supported by diaphragm wall and multi uplift piles in coastal areas has been rarely reported. In this work, a case study is conducted to investigate the mechanical characteristics of such excavation. A numerical model is established using the ABAQUS finite element platform, and its effectiveness is evaluated by comparing with the field monitoring data. After evaluation, the effects of uplift piles on excavation-induced deformations are investigated. The results show that the maximum wall deflections (δhm) are 0.02%–0.22% of the excavation depth (He), with the ground surface settlements of less than 0.6%·He and the settlement influence zone extending beyond 4He. As the soil is excavated, the top wall shows outward deformations to the active zone, and the transverse support is under tension. The use of combined diaphragm wall and multi uplift piles reduces the embedment ratio of diaphragm wall to a minimum value of 0.14 and decreases the δhm and rebound of base soil (δvrm) by 42% and 63%, respectively. A design suggestion is proposed for pile diameter (D), pile length (L), and pile spacing (S) to fall within the range of 0.4–0.8 m, 10–20 m and 6–8 D, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An improved method for rockbolt fracture is proposed in this paper to determine the exact fracture position of rockbolts simulated using cable structural elements (cableSELs) in FLAC3D. This method employs the total elongation of the free segment of the rockbolt as the fracture criterion. The maximum deformation position is identified by comparing the length of each cableSEL in the free segment, leading to the fracture. The simulation results validated through a rockbolt tensile test closely match actual conditions. The proposed method was used to optimize the roadway support in deep extra-thick coal seams (DECSs). Optimized parameters were obtained by simulating and analyzing different lengths and spacings of rockbolts and anchor cables. The field implementation conducted shows that the optimized deformation and support strength of the roadway meet safety needs. [ABSTRACT FROM AUTHOR]

Characterized by long spans, low aspect ratios, and intricate construction sequences, super-large cross-section tunnels present substantial construction risks. Therefore, the selection of the optimal excavation method and construction sequence is crucial for ensuring the safety of tunnel construction and minimizing project costs. This paper takes a super large transverse-section highway tunnel as a case study, employing field monitoring data combined with ABAQUS software to analyze the stress and deformation of surrounding rock and support structures under different excavation methods. The findings reveal that the deformation of surrounding rock and support structures excavated by the Double-Side Drift Method is smaller than those caused by the three-benching seven-step method and the CRD excavation method. Nevertheless, the significant stresses of surrounding rock and support structures are released by the Double-Side Drift Method, leading to potential stress concentrations. Thus, it is necessary to ensure the rapid completion of early support and quick sealing of the tunnel. Furthermore, the sixth process achieves smaller deformation (including arch displacement and surface settlement) of the tunnel, a shorter construction period, and lower economic costs when compared to other construction processes. Consequently, it can obviously be concluded that both the Double-Side Drift Method and the sixth construction process stand out as the most appropriate choices for excavating super large cross-section tunnels. The insights obtained from this study provide theoretical guidance for the design and construction of similar tunnel projects. [ABSTRACT FROM AUTHOR]

Rolling dynamic compaction (RDC) has been found to be useful for compaction soils and is now widely used globally. Because RDC is not often used in soft soils with poor engineering properties, field monitoring was used to study the soft clay embankment responses under RDC conditions in this study. Analysis of the monitoring data revealed that the response of the soil occurred mainly in the first 20 passes. Field monitoring revealed a strong correlation between settlement, horizontal displacement, and pore water pressure. The depth of impact of RDC on the soft soil embankment was between 3 and 3.5 m. Although settlement prediction is an important issue for construction, there is a lack of prediction methods for RDC-induced soil settlement. In this study, we used three different machine learning algorithms: random forest regression (RFR), multilayer perceptron (MLP), and extreme gradient boosting (XGBoost) to predict the total settlement and uneven settlement induced by RDC on the soft soil embankment. The three prediction models were compared, and the predictive accuracy of these models was assessed. This study analyzes and summarizes the effect of RDC application on a soft clay embankment and explores the machine learning method used for settlement prediction based on monitoring data, which provides some methods and ideas for research on the application of RDC on soft soil foundations. [ABSTRACT FROM AUTHOR]

During the construction of a new tunnel overcrossing existing tunnels at close proximity, the existing tunnels should be protected by protective structures and/or ground improvement measures. However, the construction of these structures and ground improvement may cause movement or deformation to the existing tunnels, potentially jeopardizing their operational safety, particularly under soft soil and sensitive ground conditions. This study presents the results of a year-long field monitoring program focusing on the movement of two underlying subway tunnels during different construction phases of an overcrossing cut-and-cover tunnel. Protective structures/measures for the existing subway tunnels included the construction of H-pile walls, deep soil mixing, cast-in-situ bored piles, and staged excavation for the new tunnel. In terms of construction-induced movement to the existing subway tunnels, it was found that the construction of H-pile walls induced the largest vertical settlement, the deep soil mixing operations induced the largest horizontal displacements, and the staged excavation induced the largest uplift. Although the maximum horizontal displacement at the springline of a subway tunnel near the center of the construction area slightly exceeded the alarm value, the implemented protective structures/measures were effective in reducing the total horizontal and vertical displacements of the existing tunnels. [ABSTRACT FROM AUTHOR]

There have been ever more in-situ tunnel extension projects due to the growing demand for transportation. The traditional blast scheme requires a large quantity of explosive and the vibration effect is hard to control. In order to reduce explosive consumption and the vibration effect, an optimized non-cut blast scheme was proposed and applied to the in-situ expansion of the Gushan Tunnel. Refined numerical simulation was adopted to compare the traditional and optimized blast schemes. The vibration attenuation within the interlaid rock mass and the vibration effect on the adjacent tunnel were studied and compared. The simulation results were validated by the field monitoring of the vibration effect on the adjacent tunnel. Both the simulation and the monitoring results showed that the vibration velocity on the adjacent tunnel's back side was much smaller than its counterpart on the blast side, i.e., the presence of cavity reduced the blasting vibration effect significantly. The optimized non-cut blast scheme, which effectively utilized the existing free surface, could reduce the explosive consumption and vibration effect significantly, and might be preferred for in-situ tunnel expansion projects. [ABSTRACT FROM AUTHOR]

The zoning excavation method is fully employed to control the deformation of foundation pits constructed in urban soft soil areas. However, the similarities and differences in forces and deformations between foundation pits excavated by the zonal method and those excavated by the conventional method still need to be further explored. In this study, the deformation was monitored and analyzed by taking the zonal excavation of a foundation pit of the 'New World' project in Hangzhou City as the research object. The measured results showed that the pre-built diaphragm wall for the first excavated foundation pit restricted the deformation of the first excavated diaphragm wall. The presence of extensive construction and unloading activities also changed the deformation pattern of the soil. Further, finite element simulations were carried out. The simulation results revealed that excavating the foundation pit first caused displacements in the pre-built diaphragm wall. The displacements transmitted by non-adjacent pits through the pre-built diaphragm wall were small and were concentrated at the junction of the two sub-pits. Adjacent foundation pits caused large displacements of the pre-built diaphragm wall with similar displacement patterns. The results of the study can provide effective guidance for foundation pit excavation in soft soil areas in the future. [ABSTRACT FROM AUTHOR]

Agricultural practices and meteorological conditions affect soil structure and soil hydraulic properties. However, their temporal evolution is rarely studied, and even less in the field. Thus, their dynamics are rarely taken into account in models, often leading to inconsistent results and poor decision making. In this study, the temporal evolution of water retention properties and soil structure was monitored over a 3‐year period under several contrasting production systems. Soil Water Retention Curves (SWRCs) obtained directly in the field (with soil water content and potential sensors) were compared with theoretical SWRCs predicted by pedotransfer functions (PTFs) and laboratory SWRCs measured on undisturbed samples. Bulk densities were measured every 2 months. Results indicate a high degree of variability in SWRCs over time and between production systems. The results suggest that variations in the soil water retention behaviour can be induced by crop differentiation, weed control, crop residue management, compaction during harvest, or the introduction of temporary grassland. Contrasting climatic conditions between 2021 (water excess), 2022 (severe drought) and 2023 (intermediate) provided a unique opportunity to study the resilience of the crop systems to extreme climatic conditions. Different soil drying dynamics were observed and some agricultural practices were identified as influencing the soil water retention behaviour for at least 2 years. Comparison of SWRCs showed that the theoretical curves obtained from PTFs are not a good representation of the field SWRCs, especially for less conventional agricultural practices. The laboratory curves are closer with similar trends. However, these SWRCs are not optimal for investigating the temporal evolution of water retention properties. This research also shows that agricultural practices and crops can be levers for contributing to greater food resilience against future climatic conditions. Therefore, to assess the relevance of production systems for tomorrow's needs, studies should focus on the impact of multi‐cropping systems on water retention dynamics in the field. [ABSTRACT FROM AUTHOR]

The tunneling process in water-rich silty fine sand stratum often faces challenges such as arch collapse due to the instability of the initial support arch foot. The present study focuses on the Taoshuping 3# inclined shaft section, modifies the two-side heading method (THM), and introduces the double-heading at bottom method (DBM). Field monitoring and numerical simulations are employed to investigate the formation pressure, deformation evolution, and the advantages of the construction scheme using the loosened zone and stress distribution features. The obtained results show that DBM exhibits a maximu m settlement during arch excavation, constituting approximately 36% of the total settlement, with a total value of 222.21 mm. Furthermore, the plastic zone induced by DBM ranges from 1.23 to 2 times the tunnel diameter, with vertical and horizontal surrounding soil pressures of 140.72 kPa and 46.25 kPa, respectively. DBM is markedly superior to THM. This approach reduces the formation of wedge-shaped shear bodies caused by excessive stress at the sidewalls in THM excavation. Even with tunnel excavation support, the surrounding soil maintains an arch effect, validated through calculations using Protodyakonovco theory and Terzaghi theory, verifying the efficiency of the support structure design. [ABSTRACT FROM AUTHOR]

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Objective To ensure the smooth launch of shield tunneling, local ground reinforcement is usually carried out around the originating shaft, resulting in differences in tunnel deformation on both sides of the reinforced area, which can affect tunnel structural safety. However, the characteristics and law of deformation differences are still unclear yet. Hence, it is necessary to conduct a field measurement study on the characteristics of tunnel deformation differences in the reinforced area at large-diameter shield tunnel originating end. Method Taking the large-diameter shield tunnel project on Shanghai City Railway Airport Link Line as example, based on field measurement data, the differential characteristics of shield excavation construction ground vertical deformation, tunnel vertical deformation, and tunnel lateral convergence in the reinforced area of the originating shaft are analyzed. The influence law of local ground reinforcement on deformation differences during large-diameter shield tunnel excavation in soft soil stratum is investigated. Result & Conclusion Local ground reinforcement leads to significant differences in shield tunnel deformation response. The development of ground vertical deformation transitions from 4 stages (disturbance settlement, unloading uplift, consolidation settlement, and relative stability) in the non-reinforced area to 3 stages (disturbance settlement, unloading uplift, and relative stability) in the reinforced area. For tunnel vertical deformation, fluctuating uplift dominates on the non-reinforced side, while settlement dominates in the reinforced area, causing a differential settlement of 0.022% Ls (Ls as the distance between 2 monitoring points along tunnel axis) in the critical area reaching, exceeding the warning value for differential settlement of segmental structures. Regarding tunnel lateral convergence, the reinforced area tunnel structure exhibits a vertical egg-shaped deformation, while a horizontal egg-shaped deformation in the non-reinforced area. During construction, particular attention should be paid to preventing shear damage to circumferential joint bolts and concrete damage to bolts holes caused by segmental structure settlement and convergence differences in the critical area.

Purpose: To compare MR axon radius estimation in human white matter using a multiband spiral sequence combined with field monitoring to the current state‐of‐the‐art echo‐planar imaging (EPI)‐based approach. Methods: A custom multiband spiral sequence was used for diffusion‐weighted imaging at ultra‐high b$$ b $$‐values. Field monitoring and higher order image reconstruction were employed to greatly reduce artifacts in spiral images. Diffusion weighting parameters were chosen to match a state‐of‐the art EPI‐based axon radius mapping protocol. The spiral approach was compared to the EPI approach by comparing the image signal‐to‐noise ratio (SNR) and performing a test–retest study to assess the respective variability and repeatability of axon radius mapping. Effective axon radius estimates were compared over white matter voxels and along the left corticospinal tract. Results: Increased SNR and reduced artifacts in spiral images led to reduced variability in resulting axon radius maps, especially in low‐SNR regions. Test–retest variability was reduced by a factor of approximately 1.5 using the spiral approach. Reduced repeatability due to significant bias was found for some subjects in both spiral and EPI approaches, and attributed to scanner instability, pointing to a previously unknown limitation of the state‐of‐the‐art approach. Conclusion: Combining spiral readouts with field monitoring improved mapping of the effective axon radius compared to the conventional EPI approach. [ABSTRACT FROM AUTHOR]

To investigate the performance of in-service skewed bridges, two continuous two-span steel I-girder bridges, one skewed 45° with integral abutments and the other skewed 41° with stub abutments, were instrumented during construction for long-term field monitoring. The bridges are located near each other and experience similar traffic volume and thermal variation, from roughly −18°C to 38°C (0°F to 100°F). Critical girders and cross-frames were instrumented with strain gauges and/or tiltmeters, and temperature was recorded at each sensor. Superstructure response over more than 2 years of data collection was recorded and studied, including for the in-service first-stage half bridges (temporarily for 6 months) and the full bridges. Girder cross-sections and cross-frames were within the elastic range during field monitoring, so stress directly relates to measured strain. The bridge superstructures experienced cyclic stress variation under thermal loading—there was clear linear correlation between bridge response and seasonal temperature variation, especially for decomposed girder axial stress and strong-axis bending stress. Deviation from the correlation was observed due to changes in abutment restraint during seasonal temperature variation and thermal gradient under daily temperature changes. Exterior girders were frequently unevenly heated by direct sunlight, which induced a diverging daily stress–temperature relationship compared to long-term observations. Thermal response of exterior girders is more complex than interior girders regarding both strong-axis and lateral bending, which is often not incorporated in standard bridge design procedures. Several girder bottom flanges and cross-frame members exhibited atypical increasing stress that started during the first cold-weather period; some of the stress development continued over time, regardless of long-term thermal cycles. [ABSTRACT FROM AUTHOR]

In geotechnical engineering, side friction resistance (SFR) is difficult to be measured directly. To further understand distribution law of the SFR, this paper developed a monitoring device that can directly measure the SFR. Further, a theoretical conversion formula for the elastic deformation and the SFR that considers the end effect of sensor sealing was proposed to guide the selection of sensor size and sealing material. Moreover, the monitoring device for the SFR was then calibrated using a largescale direct shear apparatus and analyzed the stability of the sensor. The calibration results revealed that under cyclic loading and unloading conditions, the linear correlation coefficient of the sensor was greater than 0.996, and the sensitivity after sealing could reach 4.836 ^s/kPa, which met requirements of the engineering application. The developed monitoring device characterized by simple testing principle, low cost, and high precision were successfully applied to an open caisson project in Harbin City, which contributes to address the difficult problem of efficiently collecting the SFR in highways, bridges, water conservancy, and other projects. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In open-cut assembled subway tunnels, foundation pit enclosure piles are typically cast in place. However, this conventional approach limits the functionality of the piles to serving as retaining structures during excavation, resulting in resource inefficiency and the underutilization of prefabrication techniques. To address this issue, a fully prefabricated pile-wall composite scheme is proposed for cut-and-cover tunnels to optimize the retaining effect of the piles and leverage the benefits of prefabricated technology. In this scheme, the retaining pile and lining are both prefabricated. The pile is the temporary retaining structure during pit excavation and a part of the sidewall. This scheme was researched and applied in Jinan, China. Field monitoring and numerical simulation were used to investigate the load transfer within the fully prefabricated pile-wall composite structure (PPWS) and its mechanical response, respectively. The results show: (1) The development of lateral earth pressures on the PPWS experienced three stages. The lateral earth pressure distribution indicates that the PPWS can fully activate the retaining effect of precast piles. (2) Following the backfilling of the joints, the horizontal displacement at the bottom of the precast pile reduced by 0.39 mm. Numerical simulation results indicate the effectiveness of precast pile restraint in PPWS. (3) The PPWS exhibited uniform deformation transition at the joints. The joints play a crucial role in coordinating deformation between the precast piles and sidewalls, utilizing the restraining effect of the precast piles. [ABSTRACT FROM AUTHOR]

Heat transfer analysis has been used to calculate the temperature distribution in bridges. Thermal boundary conditions play a critical role in this analysis. However, existing studies on thermal boundary conditions simplify the air temperature inside the bridge deck as uniform, which is not realistic and thus causes inaccurate simulation results. This study proposes a new approach to thermal boundary conditions in the heat transfer analysis of bridges. For the first time, computational fluid dynamics is used to calculate non-uniform air temperatures inside the bridge deck. In addition, non-approximate heat exchange equations for long-wave radiation are also incorporated into the approach. The techniques are applied to the 1377-m main span Tsing Ma Suspension Bridge to calculate the internal air temperatures of a deck segment. Transient heat transfer analysis is then conducted to calculate the time-dependent temperature distribution of the segment. As compared with the field monitoring results, the proposed approach can simulate the temperature distribution of the bridge with an average discrepancy of 0.88 °C and is more accurately than other existing approaches. [ABSTRACT FROM AUTHOR]

Deep excavations near subway tunnels can induce deformation, necessitating a comprehensive investigation into causal factors and mitigation strategies. Field measurements were conducted to assess both vertical and horizontal displacements of existing tunnels near a deep excavation in Shenzhen. Utilizing a validated three-dimensional finite element model that considers structure−strata interactions, this study analyzes tunnel displacements, ground movements, diaphragm wall impacts and the sensitivity of enclosure structure parameters. The results indicate that tunnel deformation correlates with enclosure structure deformation, particularly near the center of the pit. Moreover, shallow soil excavation significantly affects the vertical displacement of shallow-buried tunnels. However, the design parameters of the existing enclosure structures inadequately limit tunnel displacement. Therefore, it is crucial to intensify vertical displacement monitoring in shallow tunnels during early excavation stages and to enhance horizontal displacement monitoring during later phases. Implementing measures such as optimizing central support design or retaining soil at the pit bottom helps control maximum horizontal displacement. While support stiffness plays a greater role than retaining wall thickness, its impact on deep excavation projects is limited. [ABSTRACT FROM AUTHOR]

Introduction: Surface water from precipitation or irrigation is the sole contributor to groundwater replenishment in the Loess Plateau of China. The occurrence of landslides in the Loess Plateau is closely related to the infiltration process of surface water, and the frequent occurrence of landslides in the Loess Plateau in recent years has seriously affected the economic development and security of the Loess Plateau. Methods: To investigate the loess infiltration in deeper soil, the process of moisture infiltration in unsaturated loess is studied by field observation, theoretical analysis, and numerical simulation. Results and discussion: The research results indicated that the interstitial flow in loess could be divided into three different zones: the active zone, the stable zone (2-94 m), and the saturated zone (below 97 m); based on the matric suction and water content calculations, the L1 soil stable water content is 24.4%, which corresponds to the moisture sensor measurement of L1 loess 4 m and 7 m of stable zone data; the numerical simulation results show that whether the infiltration is continuous or intermittent, the infiltration law is the same. After 20 years, there will be a stable water content zone in the 1-8 m soil layer with a water content of 31%. The numerical results well confirm the theoretical calculation results. The research results explain the process of surface water infiltration into groundwater through thick loess and can provide an important reference for the prevention and control of geological disasters caused by water infiltration in loess areas. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Integrated pest management (IPM) uses thresholds to minimize pesticide use, and field monitoring of damaging organisms is an important component to evaluate whether or not thresholds have been breached. However, monitoring requires time and knowledge which impacts costs and benefits. In this study, we evaluated the effects of using insect pest thresholds on time effort, frequency of insecticide treatment and economics in comparison with common farm practices (business as usual) in winter wheat (WW), winter barley (WB) and winter oilseed rape (OSR). This study was done over 2 years (2018 to 2020) on 24 conventionally managed farms in North Rhine‐Westphalia (Germany). Results: Farmers spent significantly more time (42 min ha−1/season) monitoring insect pests in OSR than in WW (16 min ha−1/season) and WB (19 min ha−1/season). The use of insecticides in OSR was significantly reduced by 42% in comparison to business as usual. In cereal crops, the use of insecticide treatment was reduced by 50% but this was not significantly different to business as usual. Yields were not significantly reduced when crops were managed in accordance with IPM, and negative differences were small and not significant. However, economically, the costs of monitoring can only be recovered when labor costs and commodity prices are low and insecticide cost is high. Conclusion: Insect pest thresholds can help link the policy and environmental goals of insecticide reduction and the agronomic goal of production security. In the future, the time and cost required for monitoring should be reduced through intelligent solutions and tools, increasing the economic viability of monitoring and IPM. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This research aims to comprehensively study the deformation characteristics of an excavation pit of 7,600 m2 (117 m long, 65 m wide and 20.8 m deep) in soft clay in Shanghai, China. The deformation characteristics of the mixing pile in both the vertical and lateral directions, ground surface movement, and surface displacement in the adjacent tunnels were comprehensively investigated. The results indicated that the maximum lateral deflection was approximately 85 mm at the end of the excavation and that the maximum lateral displacement, δhm, was in the range between 0.12%He and 0.41%He. The factor of safety of the excavation was approximately 1.6, which was larger than that of most reported sites in Shanghai. The relationship between heaving and excavation depth was strong between 0.0047%He and 0.056%He, and a relatively large settlement was observed at a distance of approximately 0.2He–0.3He. The tunnel surface of the eastbound line deformed upward and inward with a maximum horizontal convergence of 4 mm. A multilayer regression model was also validated, showing a maximum discrepancy of 26.5 mm. This research provides a valuable historical case for the documentation of the deformation characteristics of excavation pits close to existing foundation pits and tunnels. [ABSTRACT FROM AUTHOR]

This paper proposed a new method for modelling joints, using anisotropic plate elements and elastic bar elements to address the issue that joints between panels are usually disregarded in numerical modelling. For small-scale deep excavations, which are frequently performed in the construction of various working shafts but have not been sufficiently studied, two numerical models were developed, using the No.1 Shaft of Tongtu Road Utility Tunnel in Ningbo, China, as a research object. One model considered the joints between the panels as proposed, while the other disregarded the joints as conventional. In comparison to the conventional method, the proposed method was validated due to yielding wall displacements that closely matched the results of the field monitoring, with a notable reduction in the error observed in the calculated displacements for the short side of the excavation. Furthermore, 34 numerical models were developed in order to investigate the influence of excavation length, depth, and diaphragm wall thickness on the relative differences between the calculated displacements obtained by the two models. The results of this study can provide references for the development of finite element models for designing small-scale deep excavation. [ABSTRACT FROM AUTHOR]

As the tunnel of Daliang mountain No. 2 highway passes through the core zone of anticline with high in-situ stress, it is prone to large deformation in initial support stage, collapse and steel frame distortion, through the comprehensive analysis of on-site monitoring measurement, surrounding rock lithology experiment, theoretical analysis, numerical simulation analysis and surrounding rock contact pressure monitoring, genetic mechanism of large deformation in anticlinal core zone of Daliang mountain No. 2 tunnel was studied. The results show that the uniaxial compressive strength of anticlinal core basalt is 23.31 MPa, tuffaceous mudstone has certain expansibility when exposed to water, it creates conditions for the deformation of surrounding rock. Due to the different lithology of rock strata, the basalt around the tunnel is in the state of independent bending shear beam after excavation. Under the condition of relatively no water, the area of plastic zone of surrounding rock increases due to the influence of groundwater recharge, and the arch waist is more obvious. Before reinforcement, the maximum settlement of the vault is 470 mm, the maximum convergence value of the arch waist is 844 mm, and the contact pressure of surrounding rock is 523.47 KPa. By adopting the comprehensive disposal method of "active adaptation +strong support" of double-layer small conduit+temporary support of middle step+temporary support of side wall, the tunnel vault deformation reduce by 87.6%, the horizontal convergence deformation reduce by 95%, maximum contact pressure of surrounding rock reduce to 128 kPa, the tunnel deformation is effectively controlled. [ABSTRACT FROM AUTHOR]

Core body temperature (Tc) is a critical aspect of homeostasis in birds and mammals and is increasingly used as a biomarker of the fitness of an animal to its environment. Periodogram and cosinor analysis can be used to estimate the characteristics of the circadian rhythm of Tc from data obtained on loggers that have limited memory capacity and battery life. The sampling interval can be manipulated to maximise the recording period, but the impact of sampling interval on the output of periodogram or cosinor analysis is unknown. Some basic guidelines are available from signal analysis theory, but those guidelines have never been tested on Tc data. We obtained data at 1‐, 5‐ or 10‐min intervals from nine avian or mammalian species, and re‐sampled those data to simulate logging at up to 240‐min intervals. The period of the rhythm was first analysed using the Lomb–Scargle periodogram, and the mesor, amplitude, acrophase and adjusted coefficient of determination (R2) from the original and the re‐sampled data were obtained using cosinor analysis. Sampling intervals longer than 60 min did not affect the average mesor, amplitude, acrophase or adjusted R2, but did impact the estimation of the period of the rhythm. In most species, the period was not detectable when intervals longer than 120 min were used. In all individual profiles, a 30‐min sampling interval modified the values of the mesor and amplitude by less than 0.1°C, and the adjusted R2 by less than 0.1. At a 30‐min interval, the acrophase was accurate to within 15 min for all species except mice. The adjusted R2 increased as sampling frequency decreased. In most cases, a 30‐min sampling interval provides a reliable estimate of the circadian Tc rhythm using periodogram and cosinor analysis. Our findings will help biologists to select sampling intervals to fit their research goals. [ABSTRACT FROM AUTHOR]

Optimizing the width of the coal pillar between two fully mechanized faces in a mine is essential for safety and efficiency. Field monitoring of the face deformation and safe abutment pressure distribution of coal pillar was conducted. Analyzing the observational data, the variation of coal pillar abutment pressure and the distribution law of plastic zone at different depths the change rate of coal pillar abutment pressure under dynamic pressure, and the evolution law of the safety section coal pillar loose ring were obtained. When the monitoring point is 40 m from the face, the deformation rate of the No. 4 coal seam haulage gate sharply increases because of the lead pressure. When the face is recovered to 0 m from the measuring point, the convergence of the sides and the roof convergence increase, and the tape is transported along the haulage gate. When the auxiliary headgate monitoring point is about – 30 m from the mining face, the deformation rate increases sharply under the influence of lead pressure. When it is – 100 m away from the face, the deformation gradually becomes stabilized. Before the measuring point is 50 m from the face, the abutment pressure reaches its peak value, and the coal enters the plastic zone (found to be at 4.5 m). The impact range of lead abutment pressure extends about 50 m in front of the face. The roof weighting step is 19 m, and the impact range is about 22 m with the face. Moreover, the monitoring data show that the width of the plastic zone of the section coal pillar is 4.0 m, and the optimal coal pillar width between the two fully mechanized faces is 18 m. Highlights: Stress change and deformation monitoring of coal pillar. Reserved width of coal pillar. Evolution characteristics of coal pillar support pressure. Evolution characteristics of plastic zone in surrounding rock. Loose ring of section safety coal pillar. [ABSTRACT FROM AUTHOR]

Purpose: Static and dynamic B0$$ {\mathrm{B}}_0 $$ field imperfections are detrimental to functional MRI (fMRI) applications, especially at ultra‐high magnetic fields (UHF). In this work, a field camera is used to assess the benefits of retrospectively correcting B0$$ {\mathrm{B}}_0 $$ field perturbations on Blood Oxygen Level Dependent (BOLD) sensitivity in non‐Cartesian three‐dimensional (3D)‐SPARKLING fMRI acquisitions. Methods: fMRI data were acquired at 1 mm3$$ {}^3 $$ and for a 2.4s‐TR while concurrently monitoring in real‐time field perturbations using a Skope Clip‐on field camera in a novel experimental setting involving a shorter TR than the required minimal TR of the field probes. Measurements of the dynamic field deviations were used along with a static ΔB0$$ \Delta {\mathrm{B}}_0 $$ map to retrospectively correct static and dynamic field imperfections, respectively. In order to evaluate the impact of such a correction on fMRI volumes, a comparative study was conducted on healthy volunteers. Results: Correction of B0$$ {\mathrm{B}}_0 $$ deviations improved image quality and yielded between 20% and 30% increase in median temporal signal‐to‐noise ratio (tSNR).Using fMRI data collected during a retinotopic mapping experiment, we demonstrated a significant increase in sensitivity to the BOLD contrast and improved accuracy of the BOLD phase maps: 44% (resp., 159%) more activated voxels were retrieved when using a significance control level based on a p‐value of 0.001 without correcting for multiple comparisons (resp., 0.05 with a false discovery rate correction). Conclusion: 3D‐SPARKLING fMRI hugely benefits from static and dynamic B0$$ {\mathrm{B}}_0 $$ imperfections correction. However, the proposed experimental protocol is flexible enough to be deployed on a large spectrum of encoding schemes, including arbitrary non‐Cartesian readouts. [ABSTRACT FROM AUTHOR]

Key message: The high-quality sap flow dataset of Melaleuca styphelioides could assists local councils in assessing tree water use and aids in the development of an urban tree sustainable planting management plan Trees have a vital part to play in urban ecosystems, offering ecological, economic, and social advantages in addition to beautifying our suburbs. Knowledge of tree water use in urban environments is crucial for facilitating urban greening when there is a perception that growing trees on the street verge on expansive soils poses a risk to pavement and buildings. Information on long-term water use by individual trees in an urban environment is essential for local councils in developing urban tree management plans for sustainable planning of trees; however, this information is scarce. Micrometeorological models have commonly been used to estimate the canopy transpiration of plants in the absence of sap flow data. However, the reliability and accuracy of these models have rarely been assessed using sap flow measurements at the field site. This study aimed to provide the water use data of four individual Australian native Melaleuca styphelioides Sm. using sap flow instruments over 25 months. Tree transpiration, estimated based on three commonly used micrometeorological models using weather parameters and tree characteristics, was assessed and compared with sap flow measurements by employing the linear regression statistical analysis. The results revealed that the modified Penman–Monteith (PM) model demonstrated the highest level of accuracy among the evaluated models, consistently yielding lower errors and providing more reliable estimates of tree water use. This suggests that this model may be more appropriate for predicting plant water use in situations where sap flow data are unavailable. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: To assess the possible influence of third-order shim coils on the behavior of the gradient field and in gradient–magnet interactions at 7 T and above. Materials and methods: Gradient impulse response function measurements were performed at 5 sites spanning field strengths from 7 to 11.7 T, all of them sharing the same exact whole-body gradient coil design. Mechanical fixation and boundary conditions of the gradient coil were altered in several ways at one site to study the impact of mechanical coupling with the magnet on the field perturbations. Vibrations, power deposition in the He bath, and field dynamics were characterized at 11.7 T with the third-order shim coils connected and disconnected inside the Faraday cage. Results: For the same whole-body gradient coil design, all measurements differed greatly based on the third-order shim coil configuration (connected or not). Vibrations and gradient transfer function peaks could be affected by a factor of 2 or more, depending on the resonances. Disconnecting the third-order shim coils at 11.7 T also suppressed almost completely power deposition peaks at some frequencies. Discussion: Third-order shim coil configurations can have major impact in gradient–magnet interactions with consequences on potential hardware damage, magnet heating, and image quality going beyond EPI acquisitions. [ABSTRACT FROM AUTHOR]

Abstract The construction of super large section (SLS) shallow buried tunnels involves challenges related to their large span, high flat rate, and complex construction process. Selecting an appropriate excavation method is crucial for ensuring stability, controlling costs, and managing the construction timeline. This study focuses on the selection of excavation methods and the mechanical responses of SLS tunnels in different types of surrounding rock. The research is based on the Yangjiashan tunnel project in Zhejiang Province, China, which is a four-line highway tunnel with a span of 21.3 m. Three sequential excavation methods were proposed and simulated using the three-dimensional finite difference method: the “upper first and lower later” side drift (SD) method, the central diaphragm method, and the top heading and bench (HB) method. The mechanical response characteristics of tunnel construction under these methods were investigated, including rock deformation, rock pressure, and the internal forces acting on the primary support. By comparing the performance of the three construction methods in rock masses of Grades III to V, the study aimed to determine the optimal construction method for SLS tunnels considering factors such as safety, cost, and schedule. Field tests were conducted to evaluate the effectiveness of the optimized construction scheme. The results of the field monitoring indicated that the “upper first and lower later” SD method in Grade V rock mass and the HB method in Grade III to IV rock mass are feasible and cost-effective under certain conditions. The research findings provide valuable insights for the design and construction of SLS tunnels in complex conditions, serving as a reference for engineers and project managers.

The construction of super large section (SLS) shallow buried tunnels involves challenges related to their large span, high flat rate, and complex construction process. Selecting an appropriate excavation method is crucial for ensuring stability, controlling costs, and managing the construction timeline. This study focuses on the selection of excavation methods and the mechanical responses of SLS tunnels in different types of surrounding rock. The research is based on the Yangjiashan tunnel project in Zhejiang Province, China, which is a four-line highway tunnel with a span of 21.3 m. Three sequential excavation methods were proposed and simulated using the three-dimensional finite difference method: the "upper first and lower later" side drift (SD) method, the central diaphragm method, and the top heading and bench (HB) method. The mechanical response characteristics of tunnel construction under these methods were investigated, including rock deformation, rock pressure, and the internal forces acting on the primary support. By comparing the performance of the three construction methods in rock masses of Grades III to V, the study aimed to determine the optimal construction method for SLS tunnels considering factors such as safety, cost, and schedule. Field tests were conducted to evaluate the effectiveness of the optimized construction scheme. The results of the field monitoring indicated that the "upper first and lower later" SD method in Grade V rock mass and the HB method in Grade III to IV rock mass are feasible and cost-effective under certain conditions. The research findings provide valuable insights for the design and construction of SLS tunnels in complex conditions, serving as a reference for engineers and project managers. [ABSTRACT FROM AUTHOR]

Vortex-induced vibration (VIV) of long-span bridges can be of large amplitude, which can influence serviceability. Therefore, it is important to predict the response of vortex-induced vibration to aid the management of long-span bridges. A novel data-driven model is proposed to predict the time history of the dynamic response of VIV events. Specifically, the proposed model consists of gated recurrent unit (GRU) neural networks and the Newmark-beta method. GRU neural networks can perform accurate sequential prediction, and the Newmark-beta method can complement the physical meaning of the middle output of the proposed model. To aid the accurate prediction of the amplitude of VIV events, the proposed model employs weighted mean square error as the loss function, which can put more emphasis on the amplitude. The proposed model is validated on measured VIV events of a long-span suspension bridge. The weighted mean absolute percentage error and Pearson correlation coefficient of the trained model indicate the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

In order to investigate the impact of advance pilot tunnel excavation in high-stress soft rock tunneling projects on the main tunnel, this study leveraged the Yulong Snow Mountain Tunnel project. Utilizing long-term field monitoring data and employing a numerical analysis model based on the finite difference program FLAC3D, the study examined the influence of advance pilot tunnel excavation on the stress of surrounding rock, rock displacement, and the distribution of plastic zones in the main tunnel, and the optimal spacing between the main hole and the horizontal guide was determined. The research findings reveal that during the excavation of the main tunnel, when the distance between the tunnel face and the monitoring section is 3. 63 times the width of the main tunnel, the crown settlement, upper convergence, middle convergence, and lower convergence values at the monitoring section account for over 80% of the final deformation. After the deformation of the surrounding rock stabilizes, both upper and middle convergence values surpass the crown settlement. Advanced excavation of parallel pilot tunnels can effectively weaken the stress environment of the main tunnel. When the distance between the main tunnel and the parallel pilot tunnel is relatively large, the weakening in the surrounding rock stress is less pronounced. As the distance between them gradually decreases, the weakening in surrounding rock stress becomes increasingly significant. However, if the distance between the main tunnel and the parallel pilot tunnel is too small, the plastic zones generated by both excavations may intersect. Taking all factors into account, it is determined that the most optimal spacing between the main tunnel and the parallel pilot tunnel is 3. 5 times the width of the parallel pilot tunnel. The crown settlement and invert uplift values of the main tunnel increase as the distance between the main tunnel and the parallel drifts decreases. The horizontal displacements of the left and right arch waists firstly decrease and then increase as the distance between the main tunnel and the parallel pilot tunnel decreases. [ABSTRACT FROM AUTHOR]

As the requirement for underground space is growing mainly in metropolitan cities, building a new underground tunnel in the locality of the in-service tunnel is one of the most common situation. Building a new tunnel might induce additional strain and stress modification resulting in damage to the in-service tunnel. This paper reviews from the research works conducted by earlier investigators on the subject matter under four categories, field monitoring, scale down modelling, numerical and theoretical approach. The purpose of this paper is to review recent developments and improve understanding of this issue. The drawbacks of each category and gray areas which need further investigation are presented in this paper. This review paper could facilitate the work of practising engineers and researchers by highlighting the problem and areas where requires further research. [ABSTRACT FROM AUTHOR]