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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2024 Vol.61 Issue.5 Published 2024-10-25 1 Design and Application of a Prefabricated Loading Platform for Full-scale Shield Tunnel Test CHEN Xiangsheng1,2,3 CHEN Weijie2 LI Rongkang2 GU Wentian1 LU Yuan1 LI Qiang2,3 SU Dong2,3 Operational shield tunnels are often affected by nearby surface loads, excavation of foundation pits, and piling activities. The external complex loads acting on the shield tunnel can disrupt the original force balance of the structure, potentially leading to excessive deformation or damage. Conducting full-scale tests is the most direct and effective means of studying the mechanical performance and failure characteristics of tunnel structures under complex loads to accurately assess the applicability of tunnel structures. To expand the applicability of full-scale tests for shield tunnels, a prefabricated steel reaction frame suitable for full-scale tests of shield tunnel structures with different sections has been proposed. The horizontal applicability of the reaction frame for different sections and sizes of structural tests is achieved through the combination of different standard units and flange-type node connections. In the vertical direction, nested column connections are adopted to effectively solve the connection and shear transfer between layers of the reaction frame. Meanwhile, the overall stress and node strength of the reaction frame were checked against four extreme loading conditions, and the feasibility of this prefabricated loading platform was further verified through the prototype structure loading test of a circular shield tunnel. 2024 Vol. 61 (5): 1-9 [Abstract] ( 107 ) [HTML 1KB] [ PDF 5146KB] ( 385 ) 10 Study on Thrust Vector Control Method for Shield Synchronous Propulsion and Assembly Based on Thrust Uniformity LIU Sijin1 SHI Linken1 WEI Yingjie1 WANG Huawei1 DU Jikai2 WANG Jun1 YU Yunxiang1 ZHU Lin3 To achieve precise control of shield attitude during the synchronous propulsion and assembly process, a study was conducted on the construction efficiency and thrust vector control method of shield synchronous propulsion and assembly, based on the Nantong-Suzhou-Jiaxing-Ningbo High-speed Railway. A thrust calculation model based on segmented lining and a thrust vector allocation method based on thrust uniformity were proposed. The effects of total thrust magnitude, thrust eccentric direction, and eccentric distance on the thrust of each cylinder were analyzed. The results indicate that, under constant tunnelling speed, assembly speed, and segment width, the cylinder stroke is the key factor affecting the efficiency of synchronous propulsion and assembly. Theoretically, the half-syn?chronous propulsion and assembly mode can improve efficiency by over 21%, while the full-synchronous mode can increase it by 47%. The thrust of each cylinder initially increases linearly with the total thrust and changes non-linearly with periodic variation as the eccentric direction varies. The thrust of the cylinders on the same side as the eccentric direction increases linearly with the eccentric distance, while the thrust of the cylinders on the opposite side decreases linearly, maintaining a constant combined force. Compared to the conventional propulsion and assembly mode, the proposed synchronous propulsion and assembly algorithm model significantly improves computational efficiency while ensuring accuracy, aligning with the concept of cylinder partition control. 2024 Vol. 61 (5): 10-20 [Abstract] ( 95 ) [HTML 1KB] [ PDF 8104KB] ( 264 ) 21 Research on the Stability of the Working Face of Large-diameter Shield Tun? nelling in Upper Hard and Lower Soft Composite Strata WEI Lixin1 YANG Chunshan1 LIU Liying1 SONG Qilong2,3 SU Dong2,3 The construction of large-diameter shield tunnels in upper hard and lower soft composite strata signifi? cantly increases the difficulty of maintaining the stability of the tunnel excavation face. To investigate the influence of the relative hardness of the upper and lower strata on the failure mechanism of the excavation face, numerical and theoretical methods were systematically employed to study the evolution mechanism of excavation face instability under different unconfined compressive strength ratios (Ku/Kl ). Numerical simulations revealed changes in the instability modes of the excavation face as Ku/Kl increased. A theoretical model predicting excavation face instability considering different strength ratios was established and validated against related theoretical models. The results indicate that:(1) as Ku/Kl increases, the ultimate support pressure first decreases rapidly, then gradually stabilizes; (2) the Ding model is most sensitive to variations in Ku/Kl and provides more conservative predictions, while the results of the Mollon model and the model proposed in this paper are closer to numerical simulations; (3) when the failure angle is taken as 45° + φ/2, the maximum ultimate support pressure required to maintain the stability of the excavation face is obtained; (4) as cohesion and internal friction angle increase, the critical Ku/Kl decreases linearly; the critical Ku/Kl remains unchanged with increasing burial ratio and soil density. 2024 Vol. 61 (5): 21-28 [Abstract] ( 100 ) [HTML 1KB] [ PDF 4482KB] ( 299 ) 29 Analysis of the Parameter Values for Settlement Trough Width Induced by Shield Tunnel Excavation in Deep Soil QI Jun1 WANG Zhongjie2,3,4 CHEN Zijun1 LIN Cungang2,3,4 XIE Wenjiang1 LIANG Yu2,3,4 To investigate the variation patterns of the deep soil settlement trough shape caused by shield tunnel exca? vation, existing empirical formulas for deep settlement were summarized. Based on the collected field measurements and model test cases—21 groups for clay, 20 groups for sandy soil, and 8 groups for gravel—the settlement trough width parameter K(z) was analyzed through back-calculation. The findings indicate that in any type of stratum, both hyperbolic and power function empirical formulas can effectively describe the trend of the settlement trough width parameter K(z) with the depth ratio. The recommended empirical parameter values for clay and sandy soil are c=0.323、0.197，and n=0.479、0.456, respectively. In gravel layers, the settlement trough width parameter shows a sim?ple linear relationship with the depth ratio. 2024 Vol. 61 (5): 29-41 [Abstract] ( 94 ) [HTML 1KB] [ PDF 5525KB] ( 376 ) 42 Theoretical Calculation Model for Stability of Tunnel Excavation Face with Pre-grouting Reinforcement ZHANG Xiao1, 2 WANG Mingnian1, 2 YU Li1, 2 WANG Zhilong1, 4 LIU Dagang1, 3 MA Zhizhong5 To support the quantitative design of pre-grouting parameters for tunnel excavation faces, a stability cal? culation model for excavation faces considering the effect of pre-grouting reinforcement was established. The ultimate equilibrium method and the strength reduction method were employed to derive a calculation formula for the stability coefficient of the excavation face. The study indicates that the theoretical model's results closely align with numerical models and experimental results, with an average relative error of 4.3%. The stability of the tunnel excavation face is improved with increase in the mechanical parameters of the surrounding rock, cohesion enhancement factor, and the pre-grouting range. The critical grouting range for the excavation face is approximately 0.4D~0.8D;when the pre-grouting range exceeds this critical value, the reinforcement effect is optimal, and the stability of the excavation face is no longer affected by the reinforcement range. A safety coefficient for the excavation face is proposed, considering parameters such as surrounding rock strength, excavation method, unsupported section length,and cohesion enhancement factor, providing a reference for the design of pre-grouting parameters. 2024 Vol. 61 (5): 42-51 [Abstract] ( 88 ) [HTML 1KB] [ PDF 6060KB] ( 293 ) 52 Study on Three-stage Grouting Diffusion Mechanism in Completely Weathered Granite Strata Considering Softening Effect WU Jianfeng1,2 ZHANG Cong1,2 WANG Shuying3 LIANG Yuehua? ZHAI Lihua? YANG Junsheng3 During the grouting process in completely weathered granite strata, the water phase in the grout under? goes a softening effect under the constraints of grouting pressure and geotechnical boundaries, which affects the grout diffusion in the three stages of penetration, compaction, and fracturing to varying degrees. This study first clarifies the softening effect in the grouting diffusion process in completely weathered granite strata and explores its impact mechanism. A theoretical model for three-stage grout diffusion in completely weathered granite strata considering the softening effect is established. The feasibility of this theoretical model is then validated through physical model experiments. Finally, the research results are successfully applied in the grouting project of Line 18 of the Guangzhou Metro. The results show that the softening effect accompanies the entire grouting process in completely weathered granite strata, with the error between theoretical derivation and physical model test results being less than 20%,proving the feasibility of the derived theoretical model. The on-site grouting results indicate that the unconfined compressive strength of the rock core soil is greater than 0.8 MPa. After tunnel excavation, the working face remains stable, forming a main grout vein and branching grout veins with good ductility, and no disaster accidents occurred during subsequent excavations. 2024 Vol. 61 (5): 52-61 [Abstract] ( 105 ) [HTML 1KB] [ PDF 4032KB] ( 253 ) 62 Mechanical Behavior Analysis of CHC Steel-concrete Composite Joints in Prefabricated Subway Stations GUO Chengxiang1 ZHANG Yanli4 HUANG Linchong2,4 HAN Bing1 LV Wenhua1 LIANG Yu2,3,4 Under the combined effects of uncertain construction loads and environmental loads, the bending stiff? ness of joints in prefabricated subway stations exhibits significant nonlinear characteristics, complicating the process of force and deformation evolution at the joints. To reveal the bending deformation development of CHC (Cshaped steel + H-shaped steel + C-shaped steel) steel-concrete composite joints in prefabricated subway stations under the combined action of axial force and bending moment, a new joint mechanical model with five bending modes is proposed. By solving the deformation and its evolution under different bending modes, the strain distribution regions of each bending mode and the identification methods are discussed. Finally, based on the mechanical model and monitoring data, the spatial-temporal distribution characteristics of circumferential joint forces were obtained. The results indicate that the calculated axial force of the prefabricated subway station joints ranges between 0 and 30 MN, and the bending moment ranges between -3 and 2 MN·m. Most of the joints are in Bending Mode I,and the mechanical response of the overall structure is more sensitive to construction loads and backfill influences. 2024 Vol. 61 (5): 62-70 [Abstract] ( 107 ) [HTML 1KB] [ PDF 4516KB] ( 288 ) 71 Settlement Analysis of Existing Prefabricated Subway Stations Induced by Overburden Backfill Load Based on Kerr Foundation Model LIU Zhaoyang1 JIANG Kai2 LIANG Yu2,3,4 The sequential soil backfilling process can lead to longitudinal uneven settlement in prefabricated struc? tures. However, existing longitudinal deformation models often neglect the deformation of prefabricated linings caused by foundation settlement. To address this, an optimized longitudinal deformation model for prefabricated subway stations is established based on an improved Timoshenko beam model on a Kerr foundation, considering foundation settlement and soil shear effects. The model is validated through comparisons with field measurements. The study shows that, compared to theoretical results from the Euler-Winkler model and the Timoshenko-Pasternak model, the proposed method not only ensures calculation accuracy but also reveals the characteristics of longitudinal deformation induced by foundation settlement. The method effectively captures the trend of vertical settlement at monitoring rings, with predicted longitudinal settlement values showing good agreement with measured data, having an error of only 0.3%. Under the combined effects of overburden load and foundation settlement, buckling occurs in the prefabricated structure, forming a new stable structure, which explains the discontinuous deformation between rings and joints in prefabricated structures. 2024 Vol. 61 (5): 71-78 [Abstract] ( 103 ) [HTML 1KB] [ PDF 3557KB] ( 261 ) 79 Intelligent Identification Method of Surrounding Rock Grades of Tunnel Face Based on Drilling Parameters XU Jianfeng1 ZHANG Xiangchuan1 QIN Guifang1 KUANG Huajiang1 LIU Guanghui1 DENG Xingxing1 To address the complexities and subjectivity in traditional rock mass classification methods for drill-andblast tunnels, which have limitations when assessing complex rock masses, this study proposes an intelligent method for identifying tunnel surrounding rock grades. The method involves fitting the distribution of drilling parameters using the kernel density estimation method and employing a Naive Bayes classification algorithm for rock classification.The performance of the classification model was enhanced through cross-validation, and the method was validated using literature data. The results demonstrate that the Naive Bayes classification algorithm based on kernel density estimation can accurately classify the quality of the tunnel face surrounding rock using drilling parameters, achieving a classification accuracy of 94.0% in the test set. Furthermore, the cross-validation method improved the model′s performance, reaching a classification accuracy of 98.7% on a test set of 299 samples. 2024 Vol. 61 (5): 79-87 [Abstract] ( 106 ) [HTML 1KB] [ PDF 6139KB] ( 290 ) 88 Calculation of Horizontal Convergence Safety Factor for Tunnels in Spatially Variable Soil Based on Deep Learning LI Zhanfu1 ZHANG Yu2 WANG Jun1 LV Yanyun2,3 RUI Yi2,3,4 To improve the efficiency of using the random finite element method (RFEM) for calculating the safety factor of tunnel horizontal convergence in spatially variable soil, a spatial attention-convolutional neural network(SA-CNN) is proposed as a surrogate model for RFEM. This surrogate model takes spatially variable soil parameters as input and the tunnel horizontal convergence safety factor as output, learning the relationship between soil parameter random fields and the tunnel safety factor from a limited number of RFEM samples. It then replaces the RFEM method for calculating safety factors on larger samples. Tested on a Shanghai metro tunnel, the model shows a relative error of less than 2% compared to RFEM, with MAPE, RMSE, and MAE values below 10%, 0.12, and 0.10 respectively, and R2 above 0.8, meeting engineering accuracy requirements. Additionally, the calculation efficiency of the surrogate model is approximately 880 times higher than RFEM. 2024 Vol. 61 (5): 88-98 [Abstract] ( 130 ) [HTML 1KB] [ PDF 5224KB] ( 287 ) 99 Intelligent Recognition Method for Tunnel Smooth Blasting Borehole Residues Based on Cascade Mask Region-Convolutional Neural Network-ResNeSt KUANG Huajiang1 LIU Guanghui1 LI Dalin1 XU Xiao1 YANG Weikang1 YANG Tingfa1 DENG Xingxing1ZHAGN Yunbo2 TIAN Maohao3 In order to solve the problems such as insufficient recognition accuracy, low robustness, and slow detec‐ tion speed in existing methods for recognizing tunnel borehole residues, an algorithm named Cascade Mask RegionConvolutional Neural Network (Cascade Mask R-CNN) is proposed. This algorithm is based on the Cascade Mask R-CNN instance segmentation algorithm and utilizes the advanced ResNeSt network as its backbone (Cascade Mask R-CNN-S) to enhance the feature extraction capability, thereby improving recognition accuracy. Multi-scale training methods and learning rate adjustment strategies are employed to train the network, resulting in an intelligent recognition model that enhances the robustness of the recognition algorithm. The model's performance was compared to traditional algorithms like Cascade Mask R-CNN and Mask R-CNN using mean average precision (mAP) as the evaluation metric. The study shows that the improved algorithm achieves an average precision value of 0.415 for bounding boxes (b_mAP(50)) and 0.350 for segmentation (s_mAP(50)) at an IoU threshold of 0.5. Compared to traditional instance segmentation algorithms, the improved algorithm significantly enhances the accuracy of tunnel borehole residue recognition, with a length recognition error of only 8.3%. It also demonstrates better robustness and anti-interference capabilities in the complex working environment of tunnels. 2024 Vol. 61 (5): 99-110 [Abstract] ( 95 ) [HTML 1KB] [ PDF 10292KB] ( 236 ) 111 Pixel-Level Segmentation Method for Tunnel Lining Cracks Based on FC-ResNet Network HAN Fengyan1，2 LI Huizhen3 YANG Shaojun3 GAN Fan3 XIAO Yongzhuo1 To improve the detection accuracy and efficiency of cracks during regular tunnel inspections, this study proposes an FC-ResNet algorithm for tunnel lining crack detection by using ResNet as the backbone feature extraction network, incorporating U-net's "encoder-decoder" structure and optimizing network feature layers. The algorithm achieves pixel-level segmentation of lining cracks. To verify its effectiveness and reliability, a comparative validation was conducted using CrackSegNet and U-net. The results show that the proposed algorithm demonstrates excellent detection performance, with a pixel accuracy, mean Intersection over Union (mIoU), and F1-score of 99.2%, 87.4%, and 0.87, respectively, on the test set. These results are superior to those of CrackSegNet and U-net,and the detection time per image is 122 ms, better than CrackSegNet and comparable to the simpler U-net. Based on the FC-ResNet algorithm, an intelligent recognition system for tunnel lining cracks was developed, enabling accurate and fast intelligent recognition of cracks in actual tunnel engineering linings. 2024 Vol. 61 (5): 111-119 [Abstract] ( 101 ) [HTML 1KB] [ PDF 4492KB] ( 237 ) 120 Research on Real-time Prediction of Shield Cutterhead Torque Based on TCN-LSTM FENG Tong1 HU Jinjian2 LI Yan1 ZHANG Jian2 LIANG Yu3,4 FENG Tugen2 The shield cutterhead torque reflects the mechanical interaction characteristics between the cutterhead and the stratum. Accurately predicting torque changes in real-time can help adjust tunnelling parameters in advance, ensure smooth machine operation, and reduce cutting tool wear. Therefore, this paper proposes a deep learning model based on Temporal Convolutional Network (TCN) and Long Short-Term Memory (LSTM) for real-time prediction of cutterhead torque. The results indicate that the TCN-LSTM model can capture the local features of the input parameters and establish long-term dependencies, achieving the highest prediction accuracy compared to other models. The model performs stably in multi-step predictions, enabling longer lead-time predictions of cutterhead torque. A 4∶1∶1 data set split ratio yields the optimal performance for the prediction model. 2024 Vol. 61 (5): 120-128 [Abstract] ( 105 ) [HTML 1KB] [ PDF 5771KB] ( 242 ) 129 Research on the Measurement Method of Spoil Volume on Shield Tunnel Belt Conveyor Based on Laser Point Cloud and Visual Technology CAI Gang1 YUE Zeyu4 ZHAO Qiang3 CAO Xu3 LIANG Yu2，4，5 To improve the accuracy and automation level of volume measurement for excavated soil during tunnel construction, a method for measuring the volume of excavated soil in shield tunnels based on laser point cloud and vision technology is proposed. The system hardware includes two single-line laser radars and one 4 K camera. The two laser radars are used to collect cross-section point cloud and longitudinal point cloud data, while the camera captures video information around the equipment. An improved optical flow method is used to determine the motion status of the conveyor belt. By combining the Triangle Accumulated Cross-sectional Area method (TACA) with the improved Adaptive Edge Iterative Closest Point (AE-ICP) algorithm, accurate measurement of the cross-sectional area of the excavated soil is achieved, and the volume of excavated soil is obtained through numerical integration using the Simpson′s rule. Experimental results indicate that this method demonstrates high measurement accuracy and robustness in complex tunnel environments, with the relative error of volume measurement controlled within 5% and the average error of speed measurement within 1%, showing promising prospects for engineering applications. 2024 Vol. 61 (5): 129-137 [Abstract] ( 106 ) [HTML 1KB] [ PDF 3693KB] ( 227 ) 138 Research on Grouting Volume Prediction for Underground Water-sealed Caverns Based on TPE-GBT Model OUYANG Shaoming1 DING Changdong2 DING Xiang1 ZHANG Yihu2 CAO Lei3 LIU Qian2 To improve the prediction of grouting volume and seepage control effects, which are difficult to assess due to the strong concealment of grouting construction, this study explores the establishment of an efficient and accurate grouting volume prediction model based on extensive on-site construction data and machine learning methods. The Gradient Boosting Trees (GBT) model is introduced to predict the unit cement consumption during the grouting process, and the Tree-Structured Parzen Estimator (TPE) algorithm is used to optimize the hyperparameters of the GBT model to enhance its prediction accuracy and generalization ability. The research results indicate that: (1) In the pre-grouting test dataset, the coefficient of determination (R2) of the TPE-GBT unit cement consumption prediction model reaches 0.80, with a mean absolute percentage error (MAPE) of 0.241 4. In the post-grouting test dataset, the model's R2 reaches 0.84, with a MAPE of 0.281 0, both of which are within an acceptable range of prediction accuracy,significantly improving the prediction accuracy compared to traditional linear regression models and GBT models;(2) Sensitivity analysis of input parameters using SHAP (Shapley Additive Explanations) values reveals that the pregrouting permeability contributes most significantly to model predictions and is a key control parameter in grouting engineering; (3) Under certain surrounding rock conditions, selecting an appropriate grouting pressure and using sequential construction methods can enhance grouting seepage control effects. 2024 Vol. 61 (5): 138-145 [Abstract] ( 97 ) [HTML 1KB] [ PDF 2635KB] ( 252 ) 146 Numerical Simulation of Variable Frequency Seepage Flow in Tunnel Surrounding Rock Joint Fractures LI Dong1 ZHOU Yue2 WANG Feng3 LI Weipeng4 YE Jiexian5 CAO Xiong1 BAI Zhenchao5 The seepage characteristics of rock joints and fractures are of significant importance for exploring the mechanisms of geological disasters induced by tunnel excavation. This study employs COMSOL numerical simula? tion software to investigate the cyclic water injection in rock joint fractures under varying amplitudes and frequencies. The results indicate that under cyclic water injection conditions, the flow pattern of the fluid within the fractures exhibits periodic changes with the inlet flow rate. Higher water injection amplitudes lead to more chaotic vortex patterns in low flow velocity regions. The permeability of the fractures also changes periodically with the inlet flow rate; specifically, when the injection flow rate decreases from its peak to its trough, the permeability increases from a trough value of 8.9×10?? m2 to 11.1×10?? m2. Moreover, the amplitude of permeability fluctuations increases with the rise in injection frequency and amplitude. Additionally, a simple and effective method for delineating flow regions is proposed, which allows for the identification and quantitative calculation of the main flow domain and vortex regions in the fractures. 2024 Vol. 61 (5): 146-155 [Abstract] ( 98 ) [HTML 1KB] [ PDF 7470KB] ( 264 ) 156 Study on the Mechanical Properties of Sandstone and Stability of Under-river Tunnels under Creep-permeability Coupling MA Jianjun1,4 TANG Rong1 LIU Cong2 HUANG Weizhen1 LIN Yuexiang3 To explore the impact of creep effects in sandstone on the long-term deformation behavior of tunnel struc? tures, this study combines indoor single-stage creep-permeability tests with FLAC 3D numerical simulations. The mechanical properties of sandstone and the stress-deformation patterns of the under-river tunnel under creep-permeability coupling were investigated. The main conclusions are as follows: (1) Single-stage loading creep tests indicate that an increase in axial pressure promotes creep deformation in sandstone, while an increase in confining pressure effectively suppresses deformation. When the seepage pressure exceeds 5 MPa, sandstone maintains a high creep rate, leading to a significant increase in axial deformation. The sensitivity factors affecting the deformation of surrounding rock are ordered as follows: seepage pressure > axial pressure > confining pressure; (2) The multi-field coupling tunnel model established using FLAC 3D accurately simulates the creep and permeability characteristics of sandstone strata in tunnels, with tunnel deformation and stress stabilizing after the eighth year of operation; (3) As the burial depth of the tunnel increases, the phenomena of tunnel crown settlement, waist convergence, and invert arch heaving become more pronounced, with maximum deformation occurring at the crown. The sensitivity of tunnel deformation is ordered as follows: crown > invert arch > waist; (4) An increase in the groundwater level significantly affects vertical settlement and horizontal convergence of the tunnel, with the most notable increase in seepage pressure occurring in the invert arch area. Special attention should be given to changes in hydraulic pressure in this region. 2024 Vol. 61 (5): 156-166 [Abstract] ( 112 ) [HTML 1KB] [ PDF 6121KB] ( 241 ) 167 Mechanical Response and Resilence Evolution Characteristics of Tunnel Structures under Additional Loads LIU Liying1 YANG Chunshan1 YU Zhiyuan2 OU Zhenfeng1 Changes in external loads inevitably induce mechanical disturbances in tunnel structures, making it cru? cial to evaluate their resilence reasonably and ensure safety. This study, based on a typical project, conducts a simulation analysis of the mechanical response of tunnel structures under additional loads. A resilence evaluation method and fortification standards for tunnels subjected to additional loads are developed. The analysis includes the resilence evolution of a specific tunnel and proposes limits for external loading during subsequent construction based on resilence requirements. The research results indicate that the response of the tunnel crown is most significant under unilateral additional loading, exhibiting characteristics of a cantilever with three-sided constraints and spatial deformation effects. A slight warping occurs on the unloaded side, leading to longitudinal twisting of the tunnel. Under additional loads, the maximum bending moment in the tunnel structure increases by 14.26%, and the maximum crack width increases by 27%. Both the maximum internal force and deformation are controllable; however, resilence is affected after structural damage. The midpoint of the tunnel structure enters a plastic state, and there is a linear relationship between the additional load and crack width, which approximates a cubic function relationship with redundancy.The resilence analysis of the case study demonstrates the feasibility of the evaluation method based on redundancy and proposes additional load limits in line with engineering characteristics and resilence requirements, providing a scientific basis for on-site implementation. 2024 Vol. 61 (5): 167-173 [Abstract] ( 97 ) [HTML 1KB] [ PDF 3949KB] ( 277 ) 174 Research on the Mechanism of Ground Deformation Induced by Shield Tunnelling under the Influence of Leakage from Pressurized Water Supply Pipelines YUAN Zuobo1 JIAN Wenyang2 WANG Duo1 LIANG Yu2 HU Song1 LIN Cungang2 QIN Yingbin1ZHAO Chenyang2 Current research on the leakage range of pressurized water supply pipelines in sandy clay strata and the interaction between pipeline leakage and shield tunnelling that induces ground deformation is still inadequate to meet engineering needs. To address this, a combination of model tests and numerical simulations was used to explore the leakage impact range, ground deformation mechanisms, and disaster prevention and control measures under the interaction of pipeline leakage and shield tunnelling. Various parameters, including pipeline water pressure and leakage duration, were tested under multiple working conditions in the pressurized pipeline leakage model experiment. Results indicate that the leakage range increases exponentially over time, and the degree of change is positively correlated with water pressure. Furthermore, a refined finite element numerical model considering the effects of pipeline leakage was established to study the impact of leakage duration and other factors on tunnel and surrounding soil deformation, leading to corresponding disaster prevention measures. 2024 Vol. 61 (5): 174-182 [Abstract] ( 94 ) [HTML 1KB] [ PDF 5111KB] ( 285 ) 183 Optimization Study of Waterproof and Drainage Technology Parameters for Deep-buried Ditches in Railway Tunnels WEI Ronghua1,2 ZHANG Kangjian1,2 ZHANG Zhiqiang1,2 Water-rich tunnels often face structural safety issues during operation due to drainage system blockages, making the optimization of waterproof and drainage technology parameters crucial. Based on the Xigu Tunnel Project of the Shenbai High-Speed Railway, this study constructs a mathematical theoretical model of seepage for deepburied ditches with external drainage methods. The image method is applied to calculate the water inflow and the water pressure behind the tunnel lining. The accuracy of the calculations is verified using a numerical simulation model, and the characteristic parameters of the deep-buried ditch drainage system are analyzed to propose corresponding drainage technology recommendations. The results show that the ditch diameter significantly impacts water inflow and lining water pressure compared to burial depth. The influence range of water pressure behind the lining is within 5 meters on either side of the invert center. There is a critical value for the grout ring's permeability coefficient affecting seepage in surrounding rock; when the permeability ratio is less than 50, a higher permeability ratio leads to less water inflow and greater water pressure behind the lining, impacting the entire ring. Under a 100-meter water head, the optimized parameters for the deep-buried ditch drainage system are: burial depth of 0.2 to 0.5 meters, radius of 0.3 to 0.5 meters, and a grout ring permeability ratio of 10 to 30. 2024 Vol. 61 (5): 183-192 [Abstract] ( 95 ) [HTML 1KB] [ PDF 5201KB] ( 270 ) 193 Analysis of the Impact of Excavation on Ground Settlement and Adjacent Pipeline Deformation Considering Spatial Variability of Soil LI Lijun Based on the foundation pit project of the Shisanyong Station of the Nansha-Zhuhai (Zhongshan) Intercity Railway, this paper constructs a finite difference model using FLAC 3D software, incorporating the spatial variability of soil. Combined with the random field theory, it analyzes the effect of foundation pit excavation on the deformation of adjacent pipelines. By introducing random field parameters, the displacement and stress distribution at various measurement points along the edge of the pit and pipelines under different coefficients of variation (COV) are simulated. Further, the influence of spatial variability of soil parameters on the deformation of the pit and adjacent pipelines is explored. The study shows that the spatial variability of the soil has a significant impact on pipeline deformation during excavation, especially in shallow layers. Increased variability in the random field adds complexity and uncertainty to displacement distribution. When the COV value is large, the range of pipeline settlement increases significantly, showing higher dispersion. Therefore, in practical construction, the spatial variability of soil parameters must be fully considered to reduce construction risks and ensure the stability of the foundation pit and the safety of adjacent pipelines. 2024 Vol. 61 (5): 193-199 [Abstract] ( 105 ) [HTML 1KB] [ PDF 3820KB] ( 276 ) 200 Study on Arching Effect of Moraine Considering Grain Composition and Moisture Content CHEN Zhimin LIU Baoli CHEN Jun ZHAI Wenhao LI Wenhao WANG Duobin CAI Yunchen To analyze the arching effect of moraines when tunnels pass through moraine layers, this study investigated the characteristics of moraines in various regions and derived the equation for the equilibrium stress arch axis of the moraine surrounding rock based on the Protodyakonor′s theory. Then, using a developed arching effect sleeve test apparatus, the arching height of the moraine was measured under different particle gradations and moisture contents to analyze their influence on arching characteristics. The study results indicate: (1) The equation for the equilibrium stress arch axis of the moraine surrounding rock is a quadratic function; (2) The mass of debris and the arching height are inversely proportional to particle size. During the free fall of granular material, the ultimate shape of frictional dilatancy self-stabilization is conical; (3) The greater the non-uniformity of the particle gradation and the smaller the particle size, the higher and less stable the arching height; (4) Under different gradations, the heightspan ratio decreases with the increase of relative particle size, but decreases with the increase in fine particles smaller than 2 mm; (5) Within a certain range, as moisture content increases, the height-span ratio gradually decreases,and the rate of decrease becomes smaller. 2024 Vol. 61 (5): 200-209 [Abstract] ( 123 ) [HTML 1KB] [ PDF 3481KB] ( 225 ) 210 Experimental Study on the Mechanical Characteristics of Shield Tunnels under Vertical Jacking YANG Chunshan1 XU Shiyang2 WEI Lixin1 CHEN Junsheng3 In vertical jacking construction, the effect of jacking reaction forces applied to the bottom of shield tunnels is a critical issue concerning the safety and stability of the surrounding soil structure. To explore the impact of vertical jacking construction on the mechanical behavior of shield tunnels, a model test was conducted using a test apparatus developed for a typical project. The test aimed to reveal the development pattern of the reaction force distribution during the jacking process and to study the mechanical and deformation characteristics of the tunnel lining and joints during different jacking stages, comparing them with theoretical calculations. The results indicate that the distribution of jacking reaction forces exhibits a typical nonlinear pattern, characterized by a significant increase before soil failure, a notable decrease after soil failure, and a gradual stabilization phase. The convergence deformation of tunnel segments undergoes four stages: a sharp increase, rapid decrease, slow decline, and eventual stabilization, affecting the opening ring and adjacent two rings. Deformation control during the jacking process should prioritize vertical reinforcement based on displacement characteristics. Longitudinal bending deformation occurs in the tunnel during the jacking stage, with the maximum gap observed between the opening rings. Due to sudden longitudinal load shifts, the largest misalignment occurs between the opening ring and adjacent rings. The segment ring joint opening and misalignment decrease significantly along the longitudinal axis, with displacement mainly resulting from segment body deformation and minimal joint deformation contribution. Under jacking forces, the tunnel crown and inner base are subject to tension and compression, respectively, with stress initially increasing and then decreasing. The upper part of the tunnel waist experiences initial compression followed by tension, while the lower part is under tension. The jacking reaction force induces a redistribution of segment stress disturbances, primarily affecting the opening ring and adjacent rings. The segment stress levels remain low, and no tensile or compressive damage is observed in the structure. 2024 Vol. 61 (5): 210-218 [Abstract] ( 98 ) [HTML 1KB] [ PDF 4596KB] ( 262 ) 219 Deformation Monitoring and Analysis during the Excavation of Deep Circular Shafts in Intercity Railway Tunnels SONG Yuepeng1 FAN Xiaofeng2 LIANG Yu2,3,4 PENG Hongguo5 ZHANG Hanwei5 The selection and design of the support system for the launching and receiving shafts of shield tunnelling are critical issues in the construction of deep-buried tunnels. Circular enclosure structures can fully utilize the arch effect of soil and do not require internal supports, providing better mechanical performance and cost-effectiveness compared to general polygonal structures. To reduce the construction difficulty and improve efficiency in the rockembedded section of composite strata, the Shenzhen International Airport-Dayawan intercity railway tunnel′s Pingju shield working shaft adopts an upper circular diaphragm wall combined with a ring beam and a lower layer of rock support using shotcrete and anchor bolts. This study analyzes changes in external groundwater, ground surface, and enclosure structure deformation during the excavation of the deep circular foundation pit. The results indicate that: surface overload and uneven external groundwater levels cause differential deformation of the wall and ground surface; the maximum horizontal deformation of the wall is generally within 0 to 0.05%H (H is the excavation depth);most ground surface settlement deformation is within 0 to 0.08%H; the vertical settlement at the top of the wall mostly ranges from 0 to 0.25%H; compared to general irregular polygonal foundation pits, the cylindrical support system shows better stability and deformation performance; the combined use of diaphragm walls with ring beams in the upper section and shotcrete and anchor bolts in the lower rock layer ensures the stability and safety of the foundation pit in composite strata. 2024 Vol. 61 (5): 219-226 [Abstract] ( 105 ) [HTML 1KB] [ PDF 5256KB] ( 271 ) 227 Research on Digital Reconstruction and Damage Analysis Methods for Lifecycle Management of Traffic Tunnels TANG Cong1 XU Shiquan1 OU Xuefeng1 QU Tongming2 LIAO Wei1 ZHOU Wentao1 Traditional tunnel management exhibits low levels of informatization and weak disaster perception capa? bilities, hindering effective and economical maintenance of tunnel damages. To address this, a systematic digital method is proposed, utilizing 2D CAD drawings, damage reports, and geological data for automated 3D reconstruction, forming an integrated model of tunnel structures, damages, and surrounding rock. Unlike conventional Building Information Modeling (BIM), this method is data-driven, enabling comprehensive analysis of disaster precursors by reconstructing models that encompass tunnel structures, damages, and surrounding rock, thus assessing the health of structures in complex geological environments and facilitating precise treatment strategies. The method was applied to evaluate the structural state of a tunnel in Guizhou, revealing a close relationship between the occurrence of tunnel damages and geological conditions. This approach visually demonstrates the correlation between tunnel damages and geological status, achieving real-time updates on damage precursors. 2024 Vol. 61 (5): 227-233 [Abstract] ( 97 ) [HTML 1KB] [ PDF 4394KB] ( 251 ) 234 Research on Causes and Countermeasures of Water Leakage in Subway Tunnels in Coastal Area ZHANG Yu1 ZHOU Lu1 SUN Xiaohe2 LI Jun1 SHI Chenghua2 LIU Shengli Focusing on the issue of water leakage in subway tunnels in coastal areas, this study investigates the leakage conditions during both the construction and operation stages of multiple lines of the Fuzhou Metro. The causes of water leakage are analyzed, and prevention measures are proposed. The study results indicate that during the construction stage, water leakage in subway stations is more severe than in shield tunnels, whereas during the operation stage, the opposite is true. The main leakage areas in subway stations are sidewalls and baseboards, while leakage in shield tunnels is concentrated at segment joints. The primary causes of station leakage are construction-related, including poor pouring quality of enclosure structures, damage to waterproof membranes, and improper treatment of construction joints. The causes of shield tunnel leakage can be categorized into four aspects: installation and construction, transportation and maintenance, material quality, and structural issues, with installation and construction problems being the most critical. To mitigate water leakage in shield tunnels, the structural design should account for construction proficiency. When construction levels are low, flat joints should replace shear key joints to significantly reduce segment damage and water leakage. 2024 Vol. 61 (5): 234-424 [Abstract] ( 112 ) [HTML 1KB] [ PDF 5535KB] ( 259 ) 243 Classification of Structural Defects and Applicability Analysis of Detection Methods for Highway Tunnel Drainage Systems ZHANG Haonan LIU Yuyang TIAN Wei ZHANG Yixiao HAN Siyuan To systematically study the structural defects in drainage systems, a survey and statistical analysis of de? fects based on different drainage components were conducted. The characteristics of the defects were analyzed, and common defect diagrams for drainage systems were designed. An accurate and efficient defect recording method was proposed. Additionally, considering inspection conditions and commonly used detection methods, targeted inspection recommendations were provided for different drainage components. The research results indicate that functional defects in concrete components include crystallization, deposition, and obstructions, while structural defects are undulation and joint displacement. For polymer components, functional defects include crystallization and deposition,with structural defects being deformation, cracking, and undulation. Inspection challenges for drainage systems include their hidden nature, the lack of standardized inspection window designs, large spacing between inspection windows, the difficulty of long-distance inspections, and the diversity in layout, diameter, structure, and material of drainage components, making it difficult for a single inspection technique to cover all components. Endoscopy is suitable for circumferential blind pipe inspection, push-rod CCTV for longitudinal blind pipe inspection, endoscopy combined with ground-penetrating radar for transverse blind pipe inspection, and self-propelled CCTV combined with ground-penetrating radar for inspecting lateral drains and central drainage channels. 2024 Vol. 61 (5): 243-251 [Abstract] ( 125 ) [HTML 1KB] [ PDF 4218KB] ( 318 ) 252 Research on Large Deformation Grading Control Technology for High Stress Red Layered Soft Rock Tunnels YANG Yi1,2 SHI Chenghua1,2,3 ZHENG Keyue1,2 PENG Menglong1,4 LOU Yili1,2 High-stress red layer soft rock is a common adverse geological condition in tunnel construction in South? west China, where tunnels often experience large deformation caused by extrusion when passing through such strata.Taking the Xinhua tunnel on the Yuxi-Mohan Railway, which passes through a high-stress red layer soft rock section, as the engineering background, this study analyzes the causes of large deformation disasters based on field geological conditions, structural damage characteristics, and deformation monitoring data. It proposes a graded control technology for large deformation of soft rock tunnels in high-stress red layers. The effectiveness of the control scheme is verified through numerical simulation and field application. The research results indicate that the stratum of the large deformation section in the Xinhua tunnel is a typical red layer soft rock with characteristics such as high deformation rate, large deformation magnitude, and prolonged deformation duration. Issues like cracking and detachment of initial support, deformation and twisting of steel arch frames, encroachment of initial support, and failure of small conduits were observed. The main causes of large deformation in the Xinhua tunnel include the coupled effects of high in-situ stress, weak strata conditions, strain softening, and volume expansion effects of red bed soft rock, as well as untimely support. The large deformation was categorized into three levels: slight, moderate, and severe, according to the stress-to-strength ratio of the surrounding rock. For each deformation level, a corresponding control scheme was proposed. Numerical simulations and field applications demonstrated that the adjusted control schemes significantly reduced the deformation of the surrounding rock, with the deformation of the surrounding rock within the reserved range under all three control schemes. 2024 Vol. 61 (5): 252-262 [Abstract] ( 105 ) [HTML 1KB] [ PDF 7442KB] ( 260 ) 263 Research on Treatment Technology for Arch Bridge-tunnel Integrated Structure Spanning a Large Karst Cave Section WANG Shengtao1 ZHANG Junru2 PENG Bo1 YAN Bo3 Based on the Jialiang No. 3 Tunnel project of the Guiyang-Nanning High-speed Railway, a treatment plan utilizing an arch bridge-tunnel integrated structure to span a large karst cave section was proposed, targeting the large karst cave revealed during tunnel excavation. Numerical simulation results and field measurement data were analyzed to study the deformation patterns of surrounding rock and support structures during the construction of the arch bridge-tunnel integrated structure. The study indicates that, due to the uneven distribution scale of the karst cave on both sides, the horizontal deformation on the right side of the tunnel is greater than that on the left. The measured stable settlement value at the arch crown is 6.03 mm, accounting for 12.06% of the settlement control value,and the horizontal convergence value is 3.05 mm, representing 6.10% of the convergence control value, indicating that the tunnel deformation meets the requirements. Excavation and support of the foundation pit at the tunnel bottom are critical stages in the treatment process. Field monitoring data showed that the maximum axial force of the steel support was 277.15 kN, the final convergence value of the steel support was 4.97 mm, and the maximum vertical displacement of the foundation pit was 2.50 mm. Upon completion of the arch bridge-tunnel integrated structure construction, the maximum vertical displacement of the arch structure was 7.14 mm, all within the monitoring alert values. These results demonstrate that the deformation of the surrounding rock and support structure during the karst cave treatment is controllable, validating the safety of using the arch bridge-tunnel integrated structure to span the large karst cave section. 2024 Vol. 61 (5): 263-273 [Abstract] ( 105 ) [HTML 1KB] [ PDF 7524KB] ( 301 ) 274 Study on the Disturbance Patterns of Roadheader Construction of Large-section Railway Tunnel Under-crossing Existing Buildings in Karst Stratum WANG Yuanye1 DING Wenqi1,2 YANG Jinjing3 QIAO Yafei1,2 DING Wenyun3 To investigate the disturbance patterns caused by the railway tunnel excavated by the boom-type road? header, which crosses undere the existing surface structures in karst strata, a karst cavity unit extraction algorithm was proposed, the three-dimensional refined finite element model was established based on a roadheader-excavated railway tunnel project, the ground settlement, the settlement and tilt rate of the existing surface structure were analyzed, and the impact of karst filling quantity on surface settlement trough was explored. The results indicate that:(1) Due to the foundation stiffness of the existing surface structure, the settlement trough caused by the boom-type roadheader construction exhibits segmented characteristics: it is approximately linear under the building and conforms to Peck formula form outside the building; (2) During the under-crossing process, the settlement and tilt rate of the existing surface structure show a three-staged variation trend, corresponding to the three-stage construction of boom-type roadheader; (3) The impact of karst cavity filling quantity on surface settlement exhibits a staged trend: When the filling quantity is less than 70 %, the maximum surface settlement decreases with increasing filling quantity. When the filling quantity exceeds 70 %, the maximum surface settlement remains stable. 2024 Vol. 61 (5): 274-284 [Abstract] ( 92 ) [HTML 1KB] [ PDF 4759KB] ( 291 )

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