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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2025 Vol.62 Issue.1 Published 2025-02-25 1 Review of Guidance and Positioning Technologies for Full-face Tunnel Boring Machines HE Boning High-precision and reliable guidance and positioning technology is crucial for the successful operation of full-face tunnel boring machines (TBMs). By reviewing the development history of guidance technologies, including the multi-prism method, laser target method, inertial navigation method, hydraulic cylinders parallel method, and computer vision method, this paper analyzes the applicability and existing challenges of each guidance technology in engineering applications from the perspectives of system principles and construction environments. The study identifies major causes of failures during use, including environmental interference, hardware malfunctions, operational errors, and equipment deformation. In practical engineering, appropriate guidance technology should be selected based on the specific application scenario of the TBM. Further research should focus on multi-source information fusion algorithms, deformation compensation, and trajectory planning to improve the accuracy and reliability of the guidance technology. 2025 Vol. 62 (1): 1-9 [Abstract] ( 82 ) [HTML 1KB] [ PDF 3785KB] ( 331 ) 10 Current Research Status and Prospects of Defect Management Systems for Operational Tunnels in China GAO Wei1 AN Ping1 HUANG Jun2 YUAN Shuo1 ZHAO Zhihao1 GE Shuangshuang1 CHEN Xikun2 There are numerous types of tunnel defects during the operation period, and various remediation methods are available. Ignoring the documentation and analysis of tunnel defect information will severely affect the efficiency of defect remediation and hinder the safe operation of tunnels. Therefore, establishing a tunnel defect management system for the efficient management of defect information is of great significance for tunnel operation and maintenance. This paper analyzes in detail the current research status of tunnel defect management systems in China from the perspectives of defect information databases and software platforms, and provides an outlook on their future development trends. The study finds that, at present, defect information databases are mainly developed based on relational databases. However, these databases have limited data capacity, and data storage is confined to text information and monitoring data. On the basis of these databases, interactive software developed using the C/S architecture(Client/Server) has poor scalability, and the information expression capability is weak. Additionally, the B/S architecture (Browser/Server) based browser platforms are limited by network environments, have poor timeliness, and cannot handle large-scale data throughput. Therefore, introducing non-relational databases, increasing the storage capacity for defect information, and incorporating defect detection images into management systems is an important direction for the future development of defect databases. Furthermore, developing an interactive management platform based on a hybrid C/S-B/S architecture, balancing in-depth analysis of defect detection data and diverse expression of defect information, is a feasible direction for the future development of software platforms. 2025 Vol. 62 (1): 10-19 [Abstract] ( 72 ) [HTML 1KB] [ PDF 5073KB] ( 263 ) 20 TBM Cutter Edge Tip Wear Phenomenon and Wear Evolution Characteristics LIU Shaoqiang1 XU Jianshu2 YANG Xiu2 TANG Qisheng1 XIE Xingfei1 GONG Qiuming1 ZHOU Xiaoxiong3 The wear of the cutters accounts for a significant portion of the engineering costs when a Tunnel Boring Machine (TBM) operating in hard rocks. Understanding the wear patterns of the cutter is a key factor in optimizing cutter design and reducing cutter consumption. Based on a TBM project in Xinjiang, this study found that the wear of the cutter edge tip is quite common under Class Ⅱ and Ⅲ rock conditions. By continuously tracking and measuring the shapes of the worn cutter edge, the changes in cutter edge shape during the wear process was analyzed from various perspectives, including tip position, edge height difference, tip height, and edge width. The results indicate a consistent trend in the evolution of the face cutter's edge shape, with the tip leaning inward and the edge being higher on the inside and lower on the outside. In contrast, the edge cutter's shape evolution exhibited two forms: one with the tip leaning inward and another with the tip leaning outward. By analysis of the stress state during the rock-breaking process of the cutter it evaluated the impact of installation radius and tilt angle on the wear shape of cutter edges. By statistically analyzing the wear volume and diameter loss of the cutter, it was found that as the installation radius increased, the wear rate of the center cutter rapidly decreased, the wear rate of the face cutter tended to stabilize,while the wear rate of the edge cutter sharply increased. 2025 Vol. 62 (1): 20-27 [Abstract] ( 70 ) [HTML 1KB] [ PDF 5224KB] ( 240 ) 28 Study on Steel Plate Cutting Deformation and Support Force for Excavation with Large Pipe Spacing in Pipe Curtain-Structure Method LIU Xiang1 LI Kuichen1 ZHANG Rui1 HUANG Jun2 ZHAO Guang2 FANG Qian3 JIANG Annan1 In case of using the pipe curtain-structure method to cross existing underground structures, it may be re? quired to excavate soils between pipes with large spacing. During excavation soils between the pipes with large spacing,the deformation pattern of the steel plate cutting process and the prediction of support force are crucial. Based on the proposed steel plate cutting scheme for pipes with large spacing in a practical engineering project, a numerical model is established. A wedge instability model for the square steel plate cutting surface between large spacing pipes is then introduced, and the analytical solution for the ultimate support force of the cutting surface is derived.Further, the influences of various factors on surface settlement and support force are analyzed. The results indicate that: (1) The theoretical calculation method has good applicability to steel plate cutting between large spacing pipes;(2) The cutting size of the steel plate has the greatest impact on surface settlement, while the pipe burial depth has the least impact; (3) As the burial depth increases, the required support pressure for the cutting surface increases,but the rate of increase decreases. Based on these findings, a construction plan of "small cutting, minimal disturbance, and frequent support" is proposed to ensure safe construction. 2025 Vol. 62 (1): 28-37 [Abstract] ( 65 ) [HTML 1KB] [ PDF 4885KB] ( 194 ) 38 Study on Shear Characteristics and Classifications of Moraine Considering Gravel Content CHEN Zhimin LIU Baoli XU Jiangtao In order to more accurately and thoroughly classify the moraine, similar materials for moraine were pre? pared based on similarity theory, and direct shear tests were designed to study the influence of gravel content on the mechanical properties of moraine. Next, gravel content was introduced, and based on entropy-weight-extended matter-element theory, a classification model for moraine was established, refining the traditional Ⅳ and Ⅴ-grade moraine into five grades, MⅠ to MⅤ. Finally, nine sections were selected, and the results calculated using the entropyweight-extended matter-element method were compared with the classfication results from the "Railway Tunnel Design Code" and the BQ method. The study shows that gravel content is an important factor affecting the mechanical properties of moraine. The results of the classification model incorporating gravel content based on entropy-weightextended matter-element theory not only correctly determine the surrounding rock grade but also refine the traditional Ⅳ and Ⅴ-grade surrounding rock into five grades, MⅠ to MⅤ. This is more conducive to the selection of tunnel support structures and parameters for moraine surrounding rock, and the method provides a new approach for the classification of similar special tunnel surrounding rocks. 2025 Vol. 62 (1): 38-47 [Abstract] ( 74 ) [HTML 1KB] [ PDF 4980KB] ( 217 ) 48 Risk Analysis of Water Inrush in a Tunnel Project in a Karst Mountain Area SHANG Haimin CUI Qingguo YU Jinqing WANG Qingang To accurately predict the risk of water inrush during tunnel construction in karst mountain areas, the Huangmujian Tunnel on a railway under construction was selected as a case study. The spatial distribution characteristics of water abundance along the tunnel were analyzed through mutual validation of comprehensive geophysical interpretation and a water abundance index model. Based on this analysis, a multi-medium equivalent continuum model for the tunnel site area was established to perform refined dynamic simulation of water inflow, achieving an integrated qualitative and quantitative analysis of water inrush risks. The research results indicate: (1) The groundwater system at the Huangmujiank tunnel site is bounded by a nearly north-south watershed on the surface, with relatively independent hydraulic connections on the east and west sides. Tunnel excavation intercepts groundwater flow from recharge to valley discharge, with dense water table contours near the tunnel and a decreasing water level drop rate as the distance from the tunnel increases. (2) The water abundance along the tunnel exhibits strong heterogeneity,with high water-abundance zones primarily located at structural features such as faults and folds in the middle section of the tunnel. These high water-abundance zones account for 3.9% of the total tunnel length. (3) Hydrological parameter zoning and assignment in the model based on the water-abundance zoning results can avoid the subjectivity of parameter zoning and improve the accuracy of water inrush risk prediction. (4) The tunnel section from DK199+400 to DK199+760 is an extremely high-risk zone for water inrush. The water inflow volume decreases logarithmically over time, with a rapid initial decline in the water inflow per unit width, which then gradually stabilizes. 2025 Vol. 62 (1): 48-55 [Abstract] ( 56 ) [HTML 1KB] [ PDF 4212KB] ( 206 ) 56 Control Measures for High Steep Side and Front Slopes at Railway Tunnel Portals in Difficult Mountainous Areas CHEN Weizhi LI Anhong WANG Hong YAO Yuchun To meet the reinforcement and protection needs for high steep side and front slopes and high-positioned dangerous rockfalls at railway tunnel portals in difficult mountainous areas, based on field survey and mapping, comprehensive exploration, and design practice, this study conducts research on the type classification, major challenges,and control measures for high steep side and front slopes at tunnel portals. The results show that high steep side and front slopes can be divided into four types: shallow cover type, rock exposed type, shallow cover-rock exposed type,and rock exposed-shallow cover type. High-positioned, steep, and concealed side and front slopes face three major challenges: difficulty in surveying and identification, high difficulty in treatment, and difficulty in material and equipment transport and construction. For dangerous rock development areas, the alignment of the railway tunnels should preferably bypass these areas. If bypassing is not feasible, the tunnel entrance should be selected according to the order: "straightly through the ridge → diagonally through the ridge → straightly through the slope → diagonally through the slope," with strict prohibition of setting tunnel portals in valleys or troughs. High-positioned, steep and concealed side and front slopes should adopt integrated "space-air-ground" exploration and identification method, and large-scale surveying should be conducted along ridges or vertical slopes. For unstable high-positioned covered side and front slopes, it should be checked, calculated and designed according to landslide engineering. For prevention and control of dangerous rockfalls, it should follow the principle of "priority removal → active reinforcement → passive protection." The control and prevention works should be considered as part of the overall project along with tunnels, bridge abutments, etc., with the construction sequence following "top-down construction, first protective works, then main tunnel and bridge works." 2025 Vol. 62 (1): 56-65 [Abstract] ( 67 ) [HTML 1KB] [ PDF 6457KB] ( 220 ) 66 Study on the Impact of Foundation Pit Construction on the Deformation of Operating Metro Tunnels and Impact Zoning HU Zhinan1 MAO Hongtao1 LIU Zhichun1 LIU Zhanliang2 MENG Xiangfei3 Based on the new transfer passage project of Beijing Metro, a combined approach of model experiment and numerical simulation was used to study the variation law of vertical displacement of existing tunnel structure caused by foundation pit excavation. The deformation mode of the existing structure was analyzed based on differential settlement under different approaching distances (B) and cover depths (h). The concept of an approaching coefficient was proposed, and a impact zoning of foundation pit construction was made according to its relationship with differential settlement. Four typical ground conditions were used to assess the risk levels of foundation pit excavation. The study showed that with the excavation of the foundation pit, the settlement of the tunnel structure exhibits a“slow-fast-slow”growth trend. Differential settlement of the existing tunnel structure caused by foundation pit construction decreases as the approaching distance increases, and increases then decreases with cover depth, ultimately reaching zero at infinite distance. When the ratio of approaching distance to cover depth (B/h) is constant, the differen? tial settlement caused by foundation pit construction is also a constant value. Based on the relationship between the approaching coefficient (k) and differential settlement, it is concluded that when 0.1 ≤ k < 5.0, it is a high-impact zone, and when k ≥ 5.0, it is a low-impact zone. The risk levels of foundation pit excavation in four typical ground conditions were identified as follows: soft soil stratum > alluvial-proluvial stratum > loess stratum > hard rock stratum. 2025 Vol. 62 (1): 66-73 [Abstract] ( 61 ) [HTML 1KB] [ PDF 3625KB] ( 166 ) 74 Dynamic Intelligent Prediction of Tunnel Surrounding Rock Geological Information Based on M-LSTM Method YANG Cunbin1,2 REN Yang,1,2 WU Yuehua1,2 HE Wanchao1,2 LI Tianbin1,2 To improve the accuracy of intelligent prediction for tunnel surrounding rock geological information, quantitative indicators such as rock integrity, rock hardness, water abundance condition, rock weathering degree,and geostress state were used as geological information parameters. By collecting various geological indicator data from the excavated sections of the tunnel and using the K-means clustering algorithm to clean the data, a highly correlated database for geological information indicators of tunnel surrounding rocks was established. Based on the sample database, a dynamic intelligent prediction model for surrounding rock geological information during tunnel construction, based on an improved long short-term memory neural network (M-LSTM), was developed. This model enables dynamic intelligent prediction of the time-series geological information data for unexcavated sections based on intelligent learning from the geological information of the excavated tunnel sections. The results show that the prediction accuracy for rock integrity is 91.6%, rock hardness is 93.8%, water abundance condition is 85.4%, rock weathering degree is 85.4%, and geostress state is 87.5%. Meanwhile, the M-LSTM method demonstrates higher computational efficiency and accuracy compared to the LSTM method and the ordinary neural network (ANN) method. 2025 Vol. 62 (1): 74-82 [Abstract] ( 70 ) [HTML 1KB] [ PDF 5492KB] ( 234 ) 83 Research on Automatic Detection Technology for Shield Tunnel Segment Misalignment Based on Point Cloud Data ZHOU Bin1,2,3,4 FENG Jianjun1,2,3,4 WEN Xiaokai3,4 RAN Mi5 Segment misalignment is a common defect in shield tunnels. To detect the segment misalignment in shield tunnels, this paper proposes an automatic detection method based on point cloud data. The method involves unfolding the 3D laser point cloud data of the tunnel into a 2D grayscale image, automatically identifying the circumferential joint positions using image processing and Hough transformation, extracting the cross-sectional point clouds on both sides of the circumferential joints, fitting the cross-sections using an improved least squares algorithm, and finally calculating the misalignment through cross-section matching. The research results demonstrate that this method can accurately detect the misalignment on both sides of the segment circumferential joints, with an overall detection accuracy within 5 millimeters and a manual verification accuracy rate exceeding 90%. This method provides an effective means for the automated detection of segment misalignment in shield tunnels. 2025 Vol. 62 (1): 83-91 [Abstract] ( 62 ) [HTML 1KB] [ PDF 3904KB] ( 202 ) 92 Study on the Vortex-induced Vibration Characteristics of Multi-lane Wide-section Submerged Floating Tunnels Based on CFD YI Zhuangpeng WANG Shen'ao TANG Xinchao CHEN Zhiwei To study the vortex-induced vibration (VIV) caused by current flow for the multi-lane wide section sub? merged floating tunnel (SFT) under water environment, which is suitable for traffic and safety needs, two numerical models for the wide cross-section with one-degree-of-freedom (1-DOF) and two-degree-of-freedom (2-DOF)were respectively established by using the Computational Fluid Dynamics (CFD) software Fluent. The distribution patterns of transverse displacement amplitude, lift coefficient amplitude, and mean drag coefficient versus the reduced current velocity for three types of wide sections (i.e., elliptical, round-end, octagonal section) are explored. By taking the round-end section as example, the time history curves and wake vortex shedding modes of the VIV under different reduced velocities, as well as the relations between the mass ratio, damping ratio and VIV characteristics of this type of wide section, were analyzed. The results show that the variation patterns of the transverse displacement amplitude, lift coefficient amplitude, and mean drag coefficient of these three types of wide sections are similar, and the VIV effects of the round-end section is the most significant. The transverse displacement and lift/drag coefficients within the locking range reach their extreme values and the wake vortex is in the“2P”mode, while those out? side the locking range are very small and the wake vortex is in the“2S”mode. The VIV effects are remarkable if the mass ratio and damping ratio are small, and a "beat" phenomenon was observed when the mass ratio was within a specific range. The numerical results based on the 2-DOF model are slightly larger than those based on the 1-DOF model, and the wake vortex shedding exhibits complex and variable patterns such as superimposed "8" shape and elliptical trajectories. 2025 Vol. 62 (1): 92-102 [Abstract] ( 64 ) [HTML 1KB] [ PDF 6084KB] ( 229 ) 103 Influence of Natural Wind on Fire Smoke Propagation in 10 km Long Highway Tunnels TAN Yinjun1,2 WANG Keli1,2 ZHANG Heng1,2 ZHANG Zhiqiang1,2 To explore the impact of natural wind on fire smoke propagation within a 10 km long highway tunnel, field tests were conducted to study the meteorological environment at the Taihangshang extra-long highway tunnel site and the distribution pattern of natural wind within the tunnel. A 3D fire dynamics model of the Taihangshang tunnel was established, incorporating a smoke exhaust shaft, to analyze fire scenarios in the middle section of the tunnel,which experiences prolonged smoke propagation. The study reveals the temperature distribution characteristics in the tunnel and the rules of smoke propagation under the influence of natural wind. The findings indicate that: (1) The natural wind speed in the Taihangshang tunnel mainly ranges from 0 to 3 m/s, with the main wind direction in the right line matching the traffic direction, having a distribution probability of 56.78% to 69.73%; (2) Opposite-direction natural wind increases the peak temperature between the fire source and the exhaust outlet, inhibiting smoke propagation; (3) Same-direction natural wind drives the smoke towards the downstream zone of the exhaust outlet,enlarging the high-temperature zone. When the same-direction wind speed reaches 2.88 m/s, the downstream space of the exhaust outlet is filled with fire smoke; (4) Natural wind inside the tunnel reduces the smoke exhaust efficiency,with wind speeds that provide a 70% guarantee rate causing a reduction in smoke exhaust efficiency by 27.76% for same-direction wind and 15.59% for opposite-direction wind. 2025 Vol. 62 (1): 103-113 [Abstract] ( 71 ) [HTML 1KB] [ PDF 7965KB] ( 202 ) 114 Study on Cutting Performance of New Wedge-flat Combined TBM Cutters in Extreme Hard Rocks GENG Qi1 HUANG Dengxia2 CHEN Jianxun3 LIU Weiwei3 LUO Yanbin3 MA Maoxun1 LI Xiaobin1 In response to the characteristic that flat type cutters of full-face rock tunnel boring machines (TBMs) have low rock-breaking efficiency but are wear-resistant in extreme hard rocks, and wedge type cutters have high rock-breaking efficiency but are prone to wear, a new wedge-flat combined cutter was proposed and the influence of cutting ring structure on rock breaking and wear were explored. Firstly, uniaxial compression, Brazilian splitting,and small-scale linear cutting tests and simulations were conducted on extremely hard diorite (exceeding 230 MPa)collected from a tunnel project to verify the accuracy of the numerical methods. Then, considering the influences of the width ratio of wedge ring segment to flat ring segment and the number of wedge or flat ring segments, full-scale numerical simulations for linear rock breaking were performed in sequence to study the change rules of rock-breaking normal force, rolling force, specific energy, and specific wear work. Research results indicate that the rock breaking load of the wedge-flat combined rings exhibited a clear multi-stage fluctuation pattern, and the load of the flat ring segment was significantly greater than that of the wedge ring segment; The ratio of wedge ring width to flat ring width had a significant impact on rock-breaking load, efficiency, and cutter ring wear, while the effect of the number of wedge or flat ring segments was not significant; It is recommended to set the width ratio of the wedge ring segment to flat ring segment to 0.5 to balance efficient rock breaking and wear resistance, and set the number of wedge or flat segments to 4 or 6. 2025 Vol. 62 (1): 114-124 [Abstract] ( 65 ) [HTML 1KB] [ PDF 6607KB] ( 297 ) 125 Study on the Mechanical Behavior and Failure Characteristics of Ultra-large Diameter Shield Tunnel Segment Structures MU Haixing1 FENG Kun1 GUO Wenqi1 YANG Shaoyi1 ZHANG Liangliang2 To investigate the mechanical behavior and failure characteristics of ultra-large diameter shield tunnel segment structures, a three-dimensional refined numerical calculation model of the segment structure based on concrete plastic damage constitutive relations was developed. The study focuses on the distribution of overall vertical displacement, joint deformation, bolt stress, reinforcement stress, crack propagation and distribution, and changes in bearing capacity under ultimate load. The results show that the overall displacement distribution of the segment structure presents a funnel shape. The vertical displacement distribution on both sides of the middle ring is asymmetric. The change in single-point vertical displacement can be divided into two stages: elastic stage and elastoplastic stage, with the largest vertical displacement at the longitudinal joint of the side ring. When the structure fails,the maximum opening of the circumferential joint is 0.075 mm, the maximum misalignment is 0.308 mm, the maximum opening of the longitudinal joint is 4.92 mm, and the maximum misalignment is 3.58 mm. However, the circumferential bolts have not yet yielded, and the bolt stress variation can be divided into three stages: linear decrease, nonlinear increase, and a brief drop. The main failure characteristic of the structure is the first appearance of tensile cracks on the inner arc surface of the middle ring, with cracks more concentrated in the corresponding position of the longitudinal joint. The main reinforcement at the mid-span yields. When the main reinforcement at the midspan yields, the safety factor of the section is 1.383, indicating that using main reinforcement yielding as a criterion for structural failure judgment is both safe and feasible 2025 Vol. 62 (1): 125-134 [Abstract] ( 66 ) [HTML 1KB] [ PDF 5452KB] ( 210 ) 135 Study on the Mechanical Response of Tunnel Segment Structures in Ultra-large Diameter Shallow-buried Shield Tunnels during Construction WAN Dongxing1 ZHANG Di2 SUN Feng2 PAN Chenxin3 ZHU Zhenwei1 XU Xiaofeng1 HE Chao1 SHEN Tuqi1 To explore the mechanical response of tunnel segment structures under complex loads during the con? struction of ultra-large diameter shallow-buried shield tunnels, this study uses the Qinwang River-crossing project as the engineering background. A three-dimensional refined calculation model was established considering the construction load combinations and boundary conditions. The model was used to analyze and compare the longitudinal uplift, circumferential misalignment, lateral deformation, longitudinal internal forces, and damage conditions of the tunnel segments under different grouting pressure and grout setting time conditions. The results show that: (1) The uplift of both the crown and the invert arch of the tunnel segment lining ring increases with the increase in grouting pressure and the extension of the grout setting time, with the grout setting time having a more significant impact on the uplift. (2) The misalignment of the segment can be divided into the upper misalignment section, transition section, lower misalignment section, and the stable section. The maximum misalignment occurs at the junction between the segments in shield shell section and in the fluid grout section, and between the segments in the fluid grout section and in the set grout section. (3) Compared to the segments in the fluid grout section, the segments in the shield shell section and the front half of segments in the set gout section are more prone to lateral deformation, which increases with the grouting pressure. (4) The tensile damage in the segments concentrates on the outer spandrel of segments in the fluid grout section and at 45° below the inner waist of the tunnel. 2025 Vol. 62 (1): 135-146 [Abstract] ( 56 ) [HTML 1KB] [ PDF 8862KB] ( 206 ) 147 Study on the Effect of Shield Tunnelling Parameters on Cutting Performance of Reinforced Concrete Based on FEM-DEM Coupling Method MU Zheng LI Fulin The shield cutting reinforced concrete piles involves a transient dynamic process between the disc cutter and the reinforced concrete. This study uses a Finite Element Method (FEM) and Discrete Element Method (DEM) coupled model to perform a three-dimensional transient dynamic analysis of the shield disc cutter cutting reinforced concrete piles. In the FEM-DEM coupled model, the mechanical behavior of concrete is described using DEM,while the effect of rebar in the concrete is simulated with FEM. The accuracy and reliability of the numerical simulation results were verified by laboratory tests, showing a good agreement between the simulation results and experimental data. Additionally, the study analyzes the impact of shield machine penetration and cutterhead rotational speed on the cutting performance of the disc cutter, providing optimal penetration, cutterhead rotational speed, and tunnelling mode for cutting reinforced concrete piles. 2025 Vol. 62 (1): 147-156 [Abstract] ( 63 ) [HTML 1KB] [ PDF 7822KB] ( 183 ) 157 Analysis of the Stress Characteristics at the Dome Type Metro Tunnel Intersection WANG Mingfa1 LIU Guoshan1 YAN Jianquan2 MAN Xinjie1 LI Hongze2 ZHOU Yangyang1 LI Weiteng2GUO Guangming1 SHAO Xing3 JIANG Weiliang1 Taking a certain subway station as the research object, this study employs model testing, numerical simu? lation, and on-site monitoring to conduct a comparative analysis of the stress characteristics of surrounding rock and support structures under two tunnel structure forms: the unidirectional arch and the dome (bidirectional arch) at the intersection section of the station's air duct and the main tunnel. The research findings indicate that the dome shape is more conducive to tunnel stability, with surrounding rock settlement reduced by approximately 7% compared to the unidirectional arch, and a smaller disturbance range to the surrounding rock. The stress state of the surrounding rock at the inner corner exhibits a trend of "three-dimensional-two-dimensional-one-dimensional" changes, leading to the formation of cracks that require close attention. The maximum tensile stress in the sprayed concrete layer is0.11 MPa, located at the inner corner of the intersection and at the cross-section between the intersection section and main tunnel. During the excavation of the lower bench, the axial force of the hollow grouting anchor bolts in the air duct and the main tunnel decreases, while the prestressed anchor bolts in the intersection section are almost unaffected. Additionally, the stress on the steel arch in this section is significantly asymmetric, with localized tensile stress occurring in the steel arch near the main tunnel side. Based on these findings, a "support first, break later"construction method is proposed, which involves first erecting an inner steel arch before dismantling the original steel arch support. On-site monitoring shows that the maximum settlement of the dome-shaped tunnel is approximately 5.2 mm, and the stress on the support structure remains within a safe range, ensuring the overall stability of the tunnel. 2025 Vol. 62 (1): 157-169 [Abstract] ( 69 ) [HTML 1KB] [ PDF 9976KB] ( 248 ) 170 Analysis of the Impact of the Three Pipe Jacking Over-crossing Construction on Existing Tunnel and Surface Deformation CHEN Wang1 PENG Yanfeng1 LIU Weizheng2 ZHANG Siyu2 CHEN Changhui1 Based on the new three pipe jacking utility tunnel crossing over existing metro tunnel in Nanchang City, a three-dimensional numerical model was established to study the deformation of the existing tunnel and ground surface under four construction sequences: first the middle, then both sides; first both sides, then the middle; right to left; and simultaneous construction of the three pipe jacking. The optimal construction sequence was selected by comparing the impact of these construction sequences on the deformation of the existing tunnel and the ground surface. The study further investigates the effect of different grouting pressures, face pressures, and anti-floating counterweights on the deformation of the existing tunnel and the ground surface. Finally, field monitoring was conducted to verify the accuracy of the simulation results and reveal the displacement and deformation patterns of the existing tunnel and the ground surface. The results show that: (1) The two-sides-first construction sequence is the optimal one, resulting in the least surface settlement, vertical tunnel displacement, and horizontal tunnel displacement, reducing them by 18.2%, 30.7%, and 23.8%, respectively, compared to the maximum values; (2) Increasing grouting pressure can suppress the development of surface settlement and tunnel displacement. Increasing face pressure can re? duce surface settlement but will increase tunnel displacement. The ratio of grouting pressure to vertical soil pressure should be controlled between 2.5 and 3.8, and the ratio of working face pressure to lateral soil pressure should be controlled between 1.88 and 2.5; (3) Applying anti-floating counterweights can suppress tunnel displacement, causing the floating of the tunnel vault to rise to a maximum value before decreasing. The reduction in displacement for counter weight ratios of 0.5 and 1 is 17% and 30%, respectively; (4) During the successive pipe jacking process, the surface settlement, settlement trough width, and tunnel displacement increase with each construction step. Due to the isolation effect, the displacement of the metro's downward line is smaller than that of the upward line; (5) Field monitoring showed a maximum surface settlement of 13.5 mm, with the maximum vertical displacement at the tunnel vault, the maximum vertical displacement at the track bed, and the maximum horizontal displacement at the tunnel waist being 1.5 mm, 1.1 mm, and 0.8 mm, respectively, all within safe limits. 2025 Vol. 62 (1): 170-182 [Abstract] ( 67 ) [HTML 1KB] [ PDF 8983KB] ( 210 ) 183 Study on the Interaction Mechanism of First and Subsequently Excavated Shatantou Tunnel Tubes under Different Clear Distance Conditions WANG Zhigang To reveal the interaction mechanism of twin tunnel tubes under dynamic excavation conditions, the Shat? antou Tunnel of the National Highway 351 reconstruction project is taken as the engineering background. The study investigates the stress distribution, deformation, and evolution of the plastic zone of the surrounding rock, as well as the loading and failure characteristics of the middle rock pillar and the internal force distribution of the support structure under dynamic excavation conditions for seven groups of different clear distances in deeply buried tunnels.The interaction mechanism of first and subsequently excavated tunnel tubes under different clear distance conditions for deeply buried tunnels with small clear distance is analyzed. The results show that during single tunnel tube excavation, stress concentration areas form in the lateral sides and the front of the tunnel face, with the maximum stress located at the arch corner, and significant settlement at the arch crown and deformation at the arch bottom. Under dynamic excavation conditions, the stress concentration at the middle rock pillar and the side in front of the sub? sequently excavated tunnel tube face near the first excavated tunnel tube is higher, peaking at a clear distance of 0.3D. When the clear distance exceeds 0.5D, a stable bearing core can form inside the middle rock pillar. Under small clear distance conditions, the internal forces in the lining of the first excavated tunnel tube are significantly affected by the excavation of the subsequent tunnel tube. At a clear distance of 0.3D, the axial force of the initial support in the first excavated tunnel tube reaches its peak at the arch waist, while the bending moment of the support peaks at the arch foot. 2025 Vol. 62 (1): 183-191 [Abstract] ( 74 ) [HTML 1KB] [ PDF 6641KB] ( 230 ) 192 Effects of Bedrock Blasting Pretreatment on Shield Tunnelling and Rock Fragmentation Mechanism CAI Haoming During shield tunnelling in complex geological conditions, factors such as bedrock protrusions and un? identified boulders can adversely affect tunnelling conditions, resulting in severe cutter damage. Using the shielddriven running tunnelling between Guanren Station and Jimei Entrepreneurship Park Station of Xiamen Metro Line 6 as the engineering background, a 3D numerical model of disc cutters cutting the bedrock after blasting and grouting pretreatment was established to investigate the effects of blasting pretreatment on rock fragmentation mechanisms. The results indicate: (1) During shield tunnelling through the bedrock section after blasting pretreatment, no sudden increases in torque or thrust occurred, the shield attitude deviation remained stable, and the required grouting volume increased by approximately 20%. (2) Blasting and grouting pretreatment altered the rock fragmentation mechanism. Under the disc cutter’s compressive forces, the low-strength grouting materials experienced extensive damage and fragmentation along the periphery of the fractured bedrock. Compared with direct cutting of bedrock,the normal load decreased by approximately fivefold, and the tangential load decreased by approximately threefold.The CSM theoretical model validated the rationality of the simulation results. (3) Increases in the penetration and grouting material strength enhanced the interaction between the cutter and the fractured bedrock, significantly increasing cutting loads. It is recommended in practical engineering to control the penetration at approximately 5 mm and grouting material strength at around 5 MPa. 2025 Vol. 62 (1): 192-200 [Abstract] ( 63 ) [HTML 1KB] [ PDF 6947KB] ( 217 ) 201 Experimental Study on the Deformation and Failure Mechanism of Red Sandstone under Groundwater Softening ZHANG Shan MENG Lubo QU Xiaoqi LI Tianbin ZHANG Yu To investigate the effects of water content on the damage degradation and deformation failure characteris? tics of red sandstone under high geostress conditions, conventional triaxial tests and triaxial creep tests were conducted on red sandstone samples with four different water content states under a high confining pressure of 20 MPa.The results show that: (1) As the water content increases, the peak stress and characteristic stress of red sandstone decrease to varying degrees, and the ratio of swelling stress to peak stress also decreases. Rock samples with higher water content generate new cracks earlier and experience swelling earlier. (2) When the water content is 3%, an accelerated creep phase appears where strain increases gradually with time. After the stress reaches the peak strength,microcracks inside the specimen maintain a“gradual cracking-sustained deformation”process under high confining pressure, with cracks slowly developing and ultimately leading to failure. (3) Based on the experimental results, the softening effect of groundwater on the gradual cracking and sustained deformation of red sandstone can be divided into three stages: the hindering deformation stage (rock pore compaction stage), the promoting deformation stage(elastic deformation stage and stable crack development stage), and the aggravating deformation stage (rapid crack expansion stage). 2025 Vol. 62 (1): 201-211 [Abstract] ( 71 ) [HTML 1KB] [ PDF 5161KB] ( 197 ) 212 Experimental Study on Dynamic Characteristics of Tunnels Crossing Multi-fault Fracture Zones in Strong Earthquake Regions WANG Haokang1,2 SHEN Yusheng1,2 PAN Xiaohai1,2 CHANG Mingyu1,2 ZHANG Xinyang1,2 SU Wei3 Based on a tunnel project crossing an active fault zone in a strong earthquake region in western China, the stress of the tunnel structure and the sliding characteristics of the fracture zone in multi-fault fracture zones were studied. The research employed an elastic foundation-based lumped mass mechanical and sliding model. A coupled tunnel-fault model was established using the finite element software combined with infinite element artificial boundaries. Through shaking table experiments, the acceleration response was analyzed to reveal the dynamic response patterns of the surrounding rock and the sliding behavior of multi-fault fracture zones during earthquakes.Results show that the amplification effect of surrounding rock acceleration decreases as the peak ground acceleration (PGA) increases. The difference in peak acceleration values between numerical simulations and experimental results ranges from 6.7% to 13.6%. At the same height along the longitudinal direction of the surrounding rock, the peak acceleration of the soil near the boundary between the fracture zone and the hanging wall or foot wall is the largest. When PGA = 0.4g, the minimum difference between the numerical simulation and the experimental results is 0.8%, indicating that the experimental method can accurately simulate seismic actions. The relative sliding rate γ of the fracture zone was used to evaluate sliding displacement. From the hanging wall to the foot wall, the relative sliding rates between fault surfaces in the fracture zone decreased in theoretical analysis, numerical simulations, and experiments from 30.9%, 33.46%, and 30.63% to 16.5%, 16.17%, and 15.3%, respectively. Sliding displacements within the fracture zones and accumulated shear stresses at fault surfaces decrease progressively. 2025 Vol. 62 (1): 212-220 [Abstract] ( 63 ) [HTML 1KB] [ PDF 5640KB] ( 171 ) 221 Experimental Study on the Catastrophic Evolution of Water and Mud Inrush in Tunnels with Karst Conduits TAO Weiming1,2 ZHU Xingyu1,3 ZHANG Zhiqiang1,3 YU Hang1,3 FAN Lei2 To investigate the multi-stage behaviors of karst conduit induced water and mud inrush disasters, including the development, evolution and formation, and to reveal the evolution mechanism of karst conduit induced disasters,a large-scale model experiment system for water and mud inrush disasters was developed and the model test was conducted based on a high-speed railway karst tunnel project. The study analyzed the stability evolution law of surrounding rock and the instability characteristics during water and mud inrush disasters in karst tunnels. The results show that: (1) The development process of karst conduit induced disasters in the model test is divided into four stages: stability, seepage, inrush and attenuation. (2) The evolution of the disaster is essentially caused by excavation unloading and groundwater seepage, which lead to stress-seepage coupling. This causes fissures to form in the rock mass ahead of the tunnel face, which eventually connect to form seepage channels, leading to instability. (3) The release rate of surrounding rock pressure is used to characterize the excavation unloading effect and the rock mass seepage failure effect during the evolution of the water and mud inrush disaster. When the tunnel face is far from the karst disaster-causing structure, the surrounding rock pressure release rate is mainly controlled by excavation unloading; when it is close, the rate is mainly controlled by the water and mud inrush disaster. (4) The time-history curves of the seepage pressure, surrounding rock pressure, and surrounding rock displacement exhibit significant precursor characteristics of the disaster, which can serve as predictive indicators and identification criteria for the disaster occurrence. The inflection points of seepage pressure and surrounding rock pressure are proposed as the critical points for the instability of the anti-inrushing rock mass, and reasonable thickness values of the anti-inrushing rock mass are provided based on practical engineering considerations. 2025 Vol. 62 (1): 221-230 [Abstract] ( 69 ) [HTML 1KB] [ PDF 6490KB] ( 204 ) 231 Experimental Study on the Macroscopic Mechanical Properties of Steel Fiber Reinforced Shotcrete in High-temperature Hydrothermal Environments YU Li1,2 QIN Youlin1,2 CHEN Lanxin1,2 XIAO Yang1,2 CHEN Chaohui1,2 WANG Songshen1,2 LIANG Zhifu3 To investigate the changes in mechanical properties of shotcrete in high-temperature hydrothermal envi? ronments and related improvement measures, tests were conducted on plain shotcrete, shotcrete with hooked-end steel fibers, and wavy steel fibers under three conditions: 20°C (room temperature water), 60°C, and 80°C hot water.The study focused on the splitting tensile strength and uniaxial compressive strength of these shotcrete mixtures.The results show that hot water accelerates the early hydration reaction of concrete and improves early mechanical properties. However, long-term exposure leads to the decomposition and reorganization of C-S-H gel, reduced densification of hydration products, and deterioration of interface performance, which causes a decrease in strength over time. Compared to room temperature (20°C), 60°C and 80°C hot water caused a 13.4% and 22.0% decrease in the 28 day tensile strength of plain shotcrete, respectively, and an 11.9% and 16.9% decrease in compressive strength.The tensile strength of hooked-end steel fiber shotcrete decreased by 14.5% and 4.0%, while compressive strength decreased by 6.5% and 1.0%. Wavy steel fiber reinforced shotcrete showed a 25% decrease in tensile strength and an 11.0% decrease in compressive strength at 60° C. In high-temperature hot water environments, shotcrete with 1.0% volume fraction of hooked-end steel fibers exhibited the best performance in enhancing both tensile and compressive strengths. 2025 Vol. 62 (1): 231-241 [Abstract] ( 64 ) [HTML 1KB] [ PDF 5946KB] ( 189 ) 242 Study on the Bending Failure Mode and Mechanism of Corrugated Steel Lining Flange Joints QU Shan1 HUANG Xuanbo2,3 DING Wenqi2,3 ZHANG Qingzhao2,3 To compare the mechanical performance of flange joints under positive and negative bending moment con? ditions, four-point bending full-scale tests of corrugated steel lining flange joints were conducted. The failure modes, M-θ curves, and strain of corrugated steel under both conditions were analyzed. A three-dimensional refined finite element model was then developed and validated based on the experimental results, from which the stress curves of the bolts and flange plates were extracted to reveal the failure mechanism of the flange joint. The study results show that: (1) The failure modes of the flange joint under positive and negative bending moments are flange plate buckling failure and failure due to the local reaching of stress limits in the flange plate and bolts, respectively; (2) The M-θ curves of the flange joint exhibit a three-stage growth trend, with the joint stiffness and ultimate bending moment under positive bending being 119.9% and 124.2% of those under negative bending moment, respectively; (3) The stresses in the corrugated steel, bolts, and flange plate under positive bending are all smaller than those under negative bending. Under positive bending, the strain in the trough and middle of the corrugated steel first undergoes tension and then compression, while under negative bending, the strain in the trough and middle remains in tension. In both conditions, the flange plate reaches yielding at the end of the elastic stage, but the bolts have not yet yielded. 2025 Vol. 62 (1): 242-249 [Abstract] ( 59 ) [HTML 1KB] [ PDF 5354KB] ( 218 ) 250 Study on the Influence of Stirrups Confinement Range on Axial Compressive Behavior of Tunnel Steel-reinforced Concrete Structures LU Junfu1 LI Ming1 ZHAO Wanqiang2 CHEN Long3 To improve the collaborative load-bearing capacity and deformation ductility of profile steel and shot? crete support, a new tunnel initial support structure was proposed, where stirrups are arranged circumferentially along the steel flange surface. Axial compression tests and numerical simulations were conducted on steel-reinforced concrete columns with and without stirrups, as well as those with different stirrup confinement ranges, to study the failure characteristics of steel-reinforced concrete columns with or without stirrups and the impact of stirrup confinement range on their load-bearing capacity. The results show that under axial compression, when there are no stirrups, the interface between the steel and shotcrete is prone to separation, preventing them from working together in bearing load. However, circumferential stirrups placed along the steel flange can effectively constrain the deformation of the concrete in the core zone, increasing the bond-slip strength between the steel and the concrete,thereby enhancing the ultimate load-bearing capacity and ductility. Compared with specimens without stirrups of the same section type, the ultimate load-bearing capacity increased by 28.29%, 30.87%, and 35.57% for specimens with circumferential stirrup extension lengths of 0 mm, 30 mm, and 60 mm, respectively. The ultimate load-bearing capacity of the stirrup-confined steel-reinforced concrete columns increased as the circumferential stirrup extension length increased. Considering all factors, the optimal stirrup extension length is 45 mm. 2025 Vol. 62 (1): 250-258 [Abstract] ( 64 ) [HTML 1KB] [ PDF 5910KB] ( 174 ) 259 Research on Construction Posture Control Technology for Shallow Buried Extra-large Section Combined Rectangular Pipe Jacking with Tight Gaps JIN Zhengxing1 GUO Ping2 ZHOU Wenpeng1 HU Qiao? SU Dong3 ZHAO Jiaxin1 SUN Bo? To better address the issues of posture control and deviation correction during construction of rectangular pipe jacking with tight gaps, this study takes the Shasan Station project of Shenzhen Metro Line 12 as a case study.A new anti-rolling device was developed, the upper and lower multi-screw conveyors for controlling soil pressure was designed, and a detachable steel ring as the tunnel portal structure was installed for left and right pipe jacking with tight gaps. Posture control technologies such as hinged hydraulic cylinder correction, cutterhead control correction, and soil grouting correction were combined to complete the jacking of extra-large section combined rectangular pipes with tight gaps. On-site measurement data show that after the pipe jacking was completed, the horizontal and vertical deviations of the pipe segments in both the left and right lines were within the design control values, meeting the specification requirements, with good control of the jacking pipe axis. The impact of secondary jacking with tight gaps on the posture of the pipe was analyzed, and it was found that the posture of the right line pipe fit well with the left line pipe. The lateral fit distance between the left and right pipes was reasonable, with no collision phenomenon observed. Although the distance between the jacking pipes was 15% larger than the set value, it still met the overall jacking construction requirements. 2025 Vol. 62 (1): 259-266 [Abstract] ( 70 ) [HTML 1KB] [ PDF 4268KB] ( 192 ) 267 Research and Application of the Local Arching Reinforcement Technology for Cracked Lining in Operational Tunnels SONG Jing WAN Li ZHANG Chang'an WU Tao In response to the issue where conventional arching reinforcement structure for tunnel cracked lining easi? ly invade the construction clearance, a local arching reinforcement technology is proposed. A local arching structure is set up in the tunnel′s roof area, with curved segments at both ends of the arching structure connected to straight segments. The curvature difference between the straight segments and the secondary lining allows the reinforcement structure′s ends to be embedded into the secondary lining at any location, effectively avoiding the clearance invasion area. The lattice girder is embedded within the local arching structure, serving both as a permanent component to increase the structure′s load-bearing capacity and as a support structure during the removal of the secondary lining. A construction method based on "segmented construction, reasonable planning, partial removal, and support while removal" is proposed to ensure structural safety during secondary lining removal. The feasibility of the technology is demonstrated through its application in reinforcing a tunnel lining, and suggestions for expanding its application and optimizing its design are provided. This technology is suitable for arcuate section tunnels and can effectively improve the applicability of arching reinforcement methods in tunnel cracked lining treatment. 2025 Vol. 62 (1): 267-274 [Abstract] ( 67 ) [HTML 1KB] [ PDF 5732KB] ( 216 ) 275 Design and Construction Technology of U-shaped Shield Pipe Erecting Machine for Green Prefabricated Integrated Utility Tunnels JIA Lianhui1 YAN Yangyi1 XUE Guangji1 DONG Yanping1 GONG Tingmin1 SHEN Chao2 To address the limitations of traditional utility tunnel construction methods, which involve large land use, high labor input, complex processes and low efficiency, this study proposes the construction concept of "Shield +Pipe erecting" for utility tunnels, which deeply integrates the "shield tunnelling technology and bridge erecting technology". A U-shield pipe erecting machine for green prefabricated utility tunnels was developed accordingly. The paper first provides a detailed introduction to the U-shield pipe erecting machine′s overall design, including the design of U-shaped shield with modular structure and stepless variable diameter function, which can adapt to the construction of utility tunnels with different cross-sections, and the design of high precision pipe erecting machine with a door-type double-leg single main beam, which can control the erection error of pipes within ±5 mm. Additionally,the blinding layer paving system and the simultaneous filling system with new economical materials“quick-setting liquid soil”are introduced, which solves the problem of mechanized paving of blinding layer and synchronous filling of side joints. Based on the utility tunnel project in Xiong′an New Area, the application of the key technologies of the U-shaped shield pipe erecting machine such as pipe erecting, blinding layer paving, side joint filling and variable cross section adaption are introduced. Compared with traditional open-cut and cast-in-place construction method,this method saves site width by 44%, improves construction efficiency by 37.5%, and has significant advantages in terms of construction safety, quality, and cost-effectiveness. 2025 Vol. 62 (1): 275-284 [Abstract] ( 54 ) [HTML 1KB] [ PDF 7735KB] ( 192 ) 285 Influence of Shield Tunnel Backfill Grouting with Red Mud-fly Ash Geopolymer on Surface Settlement WU Zihan1 LU Qingrui1 XIE Binbin1,2 CHEN Shijun1 DAI Tao1 CHEN Liming1 To address the environmental pollution caused by the extensive use of cement in traditional grouting mate? rials and to promote the resource recycling of solid wastes, a novel geopolymer grouting material was prepared using industrial waste residues such as red mud and fly ash, taking the construction of a running tunnel of the Nanchang Metro Line 1 as a case study. Comparative research was conducted on the physical properties of the newly developed material and traditional cement-based dual-liquid grouts. Using finite element numerical simulation, the influence of backfill grouting reinforcement using the two types of grouts on surface settlement was analyzed. Results indicate that the novel geopolymer dual-liquid grout exhibits excellent physical and mechanical properties. In Nanchang′s water-rich and low self-stability strata, the surface settlement values after grouting reinforcement with both types of grouts show minimal differences, with high consistency between theoretical and measured values. The red mud-fly ash geopolymer dual-liquid grout, prepared from industrial wastes, demonstrates strong environmental friendliness. 2025 Vol. 62 (1): 285- [Abstract] ( 60 ) [HTML 1KB] [ PDF 3439KB] ( 195 )

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