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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2024 Vol.61 Issue.3 Published 2024-06-25 1 “Resistance”or“Yielding”?Discussion on the Basic Concept for Dealing with Rock Squeezing Problems WANG Jianyu Based on the analysis of squeezing of weak rock under high in situ pressure, as a basic concept for dealing with squeezing problem, the“yielding principle”is pointed out in the paper, and relevant techniques for deformation releasing under a constant resistance are introduced moreover. Meanwhile the function difference between prestress anchorage cables and untensioned rock bolts are discussed and appraised. In other hand, for dealing with residual deformation, a suggestion is to arrange high deformation (compressible) fillings between the primary support and the extrados of the second lining in order to flexibly choose the timing of the second lining. 2024 Vol. 61 (3): 1-7 [Abstract] ( 189 ) [HTML 1KB] [ PDF 2757KB] ( 915 ) 8 Study on Loose Soil Pressure Calculation of Shield Tunnel Based on Linear Change of the Included Angle of Slip Surface HUANG Kan WU Qijiang DENG Xi LI Hui Given the fact that the slip surface form changes as the relative displacement changes, and with consideration of the evolution process of soil arch of shield tunnel under different ground losses, the method for calculating the linear change of included angle has been devised. The differential equation for the stress in ultimate equilibrium is analyzed in order to solve the loose soil pressure expression, and the impact of stratum arch on the boundary conditions is analyzed by considering the pattern by which the slip surface height changes as the relative displacement changes. The particle flow numerical analysis simulation has been conducted to investigate the variation pattern of soil-arch ratio in different cases and thus verify the rationality of the theoretical calculation model. As the study indicates: Average vertical stress increases as depth increases, but the increase rate gradually decreases; the soil arch evolution process is dominated by stress restoration, soil-arch ratio slowly increases from 0.326 to 0.495; bigger buried depth ratio and internal friction angle entail smaller soil-arch ratio. 2024 Vol. 61 (3): 8-17 [Abstract] ( 214 ) [HTML 1KB] [ PDF 4617KB] ( 570 ) 18 Analysis on Action Mechanism of Multi-layer Support in Soft Rock Large Deformation Tunnels with Consideration of Rheological Effects ZHU Jianlin1 WANG Lichuan2,3 L IU Zhiqiang1 MA Liyao2,3 LI Qingbin2 In order to better describe the rheological characteristics of surrounding rock under multi-layer support in soft rock tunnel with large deformation, the constitutive model of surrounding rock is assumed to be a viscoelasticplastic rheological model, and the plastic yield criterion is selected as the Mohr-Coulomb yield criterion. The multilayer support is simplified as applying different constant support forces at different times. The analytical solution of the displacement of surrounding rock under multi-layer support is derived. By comparing and analyzing with the finite difference numerical solution, it is concluded that the displacement of surrounding rock over time obtained by the two methods is basically consistent, verifying the rationality of the analytical solution. Through specific examples,the influence of multi-layer support on the stress field and displacement field of surrounding rock is analyzed. The research results show that: (1) The displacement of surrounding rock caused by the first-layer support force applied simultaneously with tunnel excavation is related to the viscoelastic-plastic effect of surrounding rock, and the incremental displacement caused by subsequently applied support forces is only related to the viscoelastic effect of sur? rounding rock; (2) With the increase of time and the increase of the support reaction force on the tunnel wall under multi-layer support, the tangential stress at the interface between the plastic zone and the viscoelastic zone of surrounding rock gradually decreases; (3) The radial displacement of surrounding rock shows a decreasing trend from the tunnel sidewall to the depth of surrounding rock, and increases with time until the deformation stabilizes. 2024 Vol. 61 (3): 18-24 [Abstract] ( 176 ) [HTML 1KB] [ PDF 2219KB] ( 539 ) 25 Stability Analysis of Surrounding Rock in High-geostress Soft Rock Tunnels under Rapid Construction BAO Yeming1 CHEN Ziquan2 ZHOU Zihan2 WANG Bo2 Studying the stability of surrounding rock in high-geostress soft rock tunnels under rapid construction with long excavation round length is of great significance for ensuring construction safety and improving construction efficiency.Firstly, the sliding instability mode of the working face is discussed to analyze the instability problem of the surrounding rock using the upper bound limit analysis method. The relationship between dissipated power and external force power is used to analyze the influence of different geological environments and excavation parameters on the stability of the surrounding rock. Secondly, the instability of the surrounding rock is disscussed using the loosening and fractured instability mode of weak surrounding rock, the evolution mechanism of the stability of surrounding rock in high-geostress soft rock tunnels is revealed using the overall safety factor method for surrounding rock. Finally,a comprehensive criterion for determining the stability of surrounding rock in high-geostress soft rock tunnels,which combines these two instability modes, is summarized and refined.The research shows that the upper bound limit analysis method can not only be used to evaluate the stability of the working face but also to infer the instability trajectory of the working face. The cohesion and internal friction angle of the rock mass have a significant influence on stability, but as they increase, the stability coefficient of the sidewall does not increase linearly, and the growth rate gradually slows down. The safety factor of the working face varies nonlinearly with the excavation round length and bench height, and the optimal excavation parameters can be determined based on the change in curvature. A method for evaluating the stability of surrounding rock in high-geostress soft rock tunnels under rapid construction is proposed, which sequentially determines whether the tunnel undergoes static sliding instability and dynamic loosening and fractured instability. 2024 Vol. 61 (3): 25-34 [Abstract] ( 163 ) [HTML 1KB] [ PDF 6152KB] ( 469 ) 35 Study on the Partitioning Method for Prefabricated Secondary Lining in Conventional Tunnelling Based on the "Contact Friction-Beam-Joint" Model ZHANG Yujin ZHOU Xiaojun YU Bingxin LI Xu ZHANG Chao In order to analyze the partitioning method and load-bearing characteristics of the prefabricated secondary lining in the composite lining of conventional tunnelling, the "contact friction-beam-joint" composite lining calculation model that takes account of the interaction between linings has been created by using the load-structure model analysis method. With consideration of the normal and tangential constraints on the initial support imposed by the surrounding rock, the contact pressure between the initial support and secondary lining in the composite lining of conventional tunnelling and the internal force of secondary lining have been analyzed. The 6 partitioning methods for prefabricated secondary lining, and the effects of the position of prefabricated block joints and the flexural rigidity of joints on the internal force of secondary lining are also investigated here. As the study results indicate: contact rigidity has major impact on the inter-layer contact pressure, and the maximum contact pressure always occurs at the arch springing of tunnel lining, so it is recommended that the contact rigidity coefficient is selected within the stable range of the contact pressure. The position of prefabricated block joints of secondary lining has major impact on the bending moment of secondary lining but minor impact on its axial force. If the flexural rigidity of joints is in the range of 0~100 MN·m·rad-1, the joints impose the greatest impact on the contact pressure, internal force and deformation of the lining, so it is recommended that the flexural rigidity value of the joints of prefabricated secondary lining is kept in the range of 50~400 MN·m·rad-1. 2024 Vol. 61 (3): 35-44 [Abstract] ( 141 ) [HTML 1KB] [ PDF 4989KB] ( 503 ) 45 Discussion on Operation Ventilation Design for the Super-long Subsea Tunnel of the Bohai Strait Channel XU Peng1 MA Zhenshuo1 WU Yimin2 WANG Zijian2 LIANG Weiming2 The Bohai Strait Channel is a forthcoming mega-project in China that spans the Laotieshan Channel. The inability to set up intermediate ventilation shafts in the super-long subsea tunnel poses significant construction challenges. This paper recommends a combined supply and exhaust ventilation scheme with longitudinal ventilation,based on a comparative analysis of the economic feasibility and difficulty of overcoming obstacles in ventilation solutions for super-long subsea tunnels. The paper provides calculations for this ventilation scheme. First, it compares Chinese and EU tunnel ventilation design standards highlighting the mismatch between the baseline emissions in Chinese standards and current emission limits. It proposes a method to calculate the required air demand for the subsea tunnel based on baseline emissions under Euro 6 emission standards, detailing the design concentrations of pollutants used in the ventilation calculations and the considerations for canceling air exchange rates. Second, air velocity calculations inside the tunnel are conducted using both Chinese and EU standards, showing that the combined supply and exhaust with longitudinal ventilation scheme is feasible under normal traffic conditions. Finally, it discusses the shift in control indicators for tunnel ventilation design from pollutants like CO and dust to critical air velocity within the main tunnel, lithium battery fire control, and rescue ventilation indicators. The paper also examines the impact of an increased proportion of new energy vehicles on operational and rescue ventilation in tunnels, aiming to provide references for the Bohai Strait Channel ventilation design and improvements to China′s ventilation standards and emission regulations. 2024 Vol. 61 (3): 45-52 [Abstract] ( 156 ) [HTML 1KB] [ PDF 2985KB] ( 529 ) 53 Study on the Flow Characteristics and Local Loss Characteristics of the Confluence Segment of Bifurcate Tunnel CHEN Zeen1,2 CHEN Xiaofeng1,2,3 KONG Xiangmiao4 ZHANG Xin5 ZHANG Yongqiang2 Presence of entrance ramp will lead to air confluence in the tunnel, so understanding the flow characteris? tics and loss characteristics of air in the confluence segment is a prerequisite for ventilation design of a bifurcate tunnel. For a bifurcate tunnel with 5°~15° included angle, the CFD method and scale model are used in the experimental study on how the confluence ratio q and included angle θ will impact the air flow and local loss in the confluence segment. As the results indicate: As q increases, the local loss coefficient ξ21 of the main line quickly decreases,while the local loss coefficient ξ31 of the ramp first increases quickly and then stabilizes. Before confluence, if the air volume ratio Q between the main line and ramp is greater than the sectional area ratio φ between them, ξ21 is mainly affected by the flow line bending, and ξ31 is mainly affected by the jet flow pressurization; if Q < φ, the main controlling factors of ξ21 and ξ31 are interchanged. If q is small, ξ21 and ξ31 will essentially remain unchanged even when the confluence included angle θ changes; if q is big, then as θ increases, ξ21 essentially remains unchanged, while ξ31 decreases. A semi-empirical formula is proposed that can accurately predict the local loss coefficient of the confluence segment of a bifurcate tunnel with 5°~15° included angle. This formula fills the gap in the design theory for confluence ventilation of bifurcate tunnel. 2024 Vol. 61 (3): 53-60 [Abstract] ( 140 ) [HTML 1KB] [ PDF 4361KB] ( 388 ) 61 Overview on Mechanical Properties of a Tunnel Lining Reinforced by High-performance Concrete CHEN Meng LIANG Zhonglong YU Hang SUN Junqi ZHANG Tong Due to the factors such as external load and environment, a tunnel in service is often vulnerable to the de? fects such as structural deformation and segment cracking, and such defects are very likely to cause tunnel safety accidents. Therefore a damaged tunnel needs to be reinforced. With a review on the domestic and foreign research into tunnel lining reinforced by high-performance concrete, the action mechanism and mechanical properties of the combination of UHPC, ECC and steel plate-high-performance concrete that are used to reinforce tunnel lining are systematically analyzed herein. For the three types of high-performance concrete that are used to reinforce tunnel lining,the synergistic effect between the reinforcing layer and lining can be achieved through interfacial bonding. Then stress redistribution occurs inside the structure, so as to enhance the bearing capacity, toughness and durability of lining. When reinforced by UHPC, the bearing capacity of a segment can increase by 30.0%~103.0%. When the tunnel lining is reinforced by ECC, the cracking toughness increases by up to 181.0%. When reinforced by steel plate and high-performance concrete, the ultimate bending moment of a segment increases by 284.0%~467.0% as compared with an unreinforced plain concrete segment. Besides, this paper offers suggestions regarding further research into the highperformance concrete used to reinforce tunnel lining. 2024 Vol. 61 (3): 61-71 [Abstract] ( 181 ) [HTML 1KB] [ PDF 6227KB] ( 472 ) 72 Variation Pattern of Surrounding Rock Bearing Arch of Deep Tunnel and Analysis on Its Impact PAN Tong1 ZHANG Junru1 DAI Yi1 CHEN Pengtao1 MA Kaimeng1,2 In order to reveal the variation pattern of the surrounding rock bearing arch of deep-buried tunnel after excavation, the mechanical model for load-bearing ring is used to derive the analytical solution of the internal and external boundaries of the surrounding rock bearing arch of deep tunnel, and the finite difference software is used to analyze and investigate the variation pattern of the surrounding rock bearing arch of deep-buried tunnel under different surrounding rock grades, different buried depths and different lateral pressure coefficients and the coupling effect of the influencing factors. As the results indicate: The ranking of the factors in terms of their influence on the surrounding rock bearing arch of deep tunnel is surrounding rock grade> buried depth of tunnel> lateral pressure coefficient; the surrounding rock grade will directly determine the scope of the bearing arch, i.e. worse surrounding rock conditions will bring greater scope of stress redistribution induced by tunnel excavation; the scope of bearing area is largely in linear relation with the buried depth of tunnel, because as the buried depth increases, both internal and external boundaries of the bearing arch will shift toward the deeper part of the surrounding rock; lateral pressure coefficient imposes the greatest influence on the form variation of the bearing arch, where the morphological characteristics of the internal and external boundaries exhibit different variation patterns as the lateral pressure coefficient changes. 2024 Vol. 61 (3): 72-84 [Abstract] ( 168 ) [HTML 1KB] [ PDF 12155KB] ( 426 ) 85 On Surrounding Rock Deformation Characteristics in a High Geostress Soft Rock Tunnel with Double-layer Initial Support CHEN Zhimin1 WANG Hong1 GONG Jun2 LI Zengyin2 PENG Yi1 In order to control the surrounding rock deformation of a tunnel in soft rock with high geostress and opti? mize the double-layer initial support structure, the Ningchan Tunnel is used as an example in this study. The numerical simulation method is used to analyze the deformation characteristics under different thickness combinations of double-layer initial support and at different construction time of the second-layer support. The field monitoring data is also used to analyze the surrounding rock deformation characteristics of single-layer and double-layer initial support, and to verify the accuracy of the numerical simulation. As the results indicate: If the thickness of the first-layer initial support is no more than 0.04 times the tunnel span, increasing the thickness of the first-layer the initial support is highly effective in controlling the deformation of tunnel crown and hance. As the thickness increases, however,the controlling effect is gradually diminished. If the thickness ratio between the first-layer and second-layer initial support is 0.8-2.7, the ratio between the surrounding rock deformation and thickness is indicative of an exponential function relation. Hance convergence is more sensitive to the construction time of the second-layer initial support than crown settlement is. If the first-layer and second-layer support are 35 cm and 20 cm in thickness, the surrounding rock deformation can be effectively controlled, and the onsite operability can be guaranteed. The period before excavation of the lower bench is completed is the period in which the surrounding rock intensively releases its stress, and the impact of the excavation-induced unloading is the dominant factor in deformation. After construction of the secondary lining, the surrounding rock rheology is the dominant factor in deformation. 2024 Vol. 61 (3): 85-95 [Abstract] ( 185 ) [HTML 1KB] [ PDF 4881KB] ( 401 ) 96 Study on Mechanical Behavior and Spatio-Temporal Deformation during Support Replacement in Soft Rock Large Deformation Tunnels HUAN Yuxiang1 TIAN Liyong2 YANG Wenbo1 LI Haoyu1 LIU Yong3 TANG Hao3 YAO Chaofan1 In view of the support replacement problem induced by support failure (exclusive of invert arch) in the soft rock large deformation tunnel on Jiuzhaigou-Mianyang Expressway, this study explores the mechanical behavior and spatio-temporal deformation characteristics during support replacement through field monitoring and numerical simulation methods. The results show that: (1) Under the research conditions, the new support near the non-replacement section bears less load, while the new support further away the non-replacement section bears more load.Among the new supports at the same distance from the non-replacement section, the one replaced earlier bears more load, and the one replaced later bears less load. (2) The position of the support replacement working face has a greater impact on the load of the new initial support than on the secondary lining, and the proportion of stress sharing between the new initial support and the secondary lining is positively correlated with the relaxation stress caused by the replacement. Conducting support replacement after improving the physical and mechanical parameters of surrounding rocks is an effective measure to solve the large deformation problem in soft rocks. (3) The displacement of the structure within 1D (D is the equivalent diameter of the tunnel) in front of and behind the non-replacement section is less affected by the support replacement, and the displacement in the middle part of the replacement section is basically the same and larger than that at both ends. (4) For tunnels with poor rock types such as soft rocks, necessary temporary protection should be applied within a range of at least 1D in front of and behind the replacement position. Grouting before replacement can play a role in pre-reinforcement, and the process of "failure-grouting-replacement-resistance" can effectively suppress the rheological effect of soft rocks. 2024 Vol. 61 (3): 96-107 [Abstract] ( 149 ) [HTML 1KB] [ PDF 9429KB] ( 510 ) 108 Study on Application of Multi-level Yielding Support System in a Highway Tunnel in Soft Rock with Large Deformation ZHANG Ziyang1 WANG Bo1 LIU Jinwei1 NING Qiran1 WANG Jie2 YU Wei1 By using the technical concept of yielding support and using the Dujiashan Tunnel Project as an example, this paper is intended to investigate the response variation pattern of surrounding rock and support structure under different combinations of yielding point and yielding quantity of multi-level yielding support. Also the supporting effects of multi-level yielding support and one-level yielding support under their optimum yielding point and yielding quantity are compared. As the results indicate: If two-level yielding support is used and the yielding point and total yielding quantity remain unchanged, then as the first-level yielding quantity decreases, the secondary-level yielding quantity increases, and the horizontal displacement of surrounding rock, crown settlement, minimum principal stress and plastic zone all decrease before increasing. If the yielding quantity remains unchanged and the first-level yielding point increases, then the secondary yielding point gradually decreases, and the crown settlement, side wall horizontal convergent displacement and surrounding rock plastic zone all increase before decreasing, but with minor margin of variation. The minimum principal stress of surrounding rock decreases before increasing, so the deformation energy released by the surrounding rock increases before decreasing. If a tunnel with large squeezing deformation is built with the two-level yielding support and the yielding quantity is released stage by stage, then the deformation energy released by the surrounding rock decreases. The support structure can effectively control the surrounding rock deformation. Stress redistribution of surrounding rock is adequately achieved. The stress and deformation of surrounding rock-structure under two-level yielding support system is more balanced than under one-level yielding support system. 2024 Vol. 61 (3): 108-118 [Abstract] ( 132 ) [HTML 1KB] [ PDF 9273KB] ( 358 ) 119 Case Study on Deformation Damage of Masonry Building Caused by Lateral Crossing of Shield Tunnel QU Hao1 ZHANG Bo1,2 ZHANG Zhenyi3 ZHANG Liyao4 Most of the research into lateral crossing of masonry building by shield tunnel conducted so far is focused on analysis of settlement and overall inclination of the masonry building. A masonry building that experiences differential settlement is susceptible to cracking, so the aforesaid two indicators are not enough to analyze the crack damage of the building. The numerical simulation calculation of lateral crossing of shield tunnel that uses conventional constitutive model does not take into account the unique structure of masonry building or the crack and stress of the masonry building. In this study, therefore, the lateral crossing of Malaqin Restaurant by the shield tunnel of Hohhot Metro Line 1 is used as the example. In the numerical simulation, finite element calculation is conducted by using the jointed masonry constitutive model. The differential settlement and strain of the building resulting from lateral crossing by the shield are analyzed by using the measurement data. As the results indicate: (1) After lateral crossing of the masonry building by a shield tunnel, the cracking area of the masonry building develops from the bottom up, the tensile strain is mostly concentrated at the lowermost part of the building, and most tensile strain regions are related to the position of the door opening. (2) The differential settlement areas of the masonry building are concentrated at the door and window openings, and the areas with major differential settlement are the areas with major strain which are more susceptible to cracking. (3) As the cohesion of masonry mortar increases, the strain and differential settlement of the masonry building gradually decrease, and the areas on the masonry building that are susceptible to cracking gradually decrease. 2024 Vol. 61 (3): 119-130 [Abstract] ( 135 ) [HTML 1KB] [ PDF 6959KB] ( 349 ) 131 Study on Numerical Simulation of Chloride Ion Erosion of Lining Segment Components under the Action of High Hydraulic Pressure CHEN Libao1 FENG Kun2 SUN Wenhao1 XING Wenjie2 PAN Jin2 GENG Junyang2 WANG Junling3 In order to investigate the migration and distribution pattern of chloride ions in segment structure, and de? termine the impact of the factors such as external hydraulic pressure conditions, chloride ion concentration, pore water pressure and erosion time on the erosion pattern of lining segment, the Jiaozhou Bay 2nd subsea tunnel in Qingdao is used as an example in this study. The numerical model for chloride ions erosion and migration in lining segment in saturated and non-saturated conditions under the action of high hydraulic pressure is created by using the COMSOL Multiphysics? finite element platform. The structural mechanics module (solid), truss module (truss), porous media dilute substance transfer module (tds) and Richards equation module (dl) are used to simulate the chloride ions erosion pattern of segment model component under the coupling action of bending load, high hydraulic pressure and chloride ion concentration. As the results indicate: The convection of chloride ions in a segment component under the action of high hydraulic pressure is mainly controlled by the water head, while their diffusion is mainly affected by concentration gradient. The chloride ion concentration-depth curve can be divided into the convection segment,transition segment and diffusion segment. 2024 Vol. 61 (3): 131-140 [Abstract] ( 154 ) [HTML 1KB] [ PDF 4734KB] ( 467 ) 141 TBM Muck Segmentation Method Based on Global Perception and Edge Refinement ZHANG Yan HUO Tao ZHANG Zhongwei MA Chunming Accurately segmenting and analyzing the muck generated during TBM excavation can reflect the geologi? cal conditions of tunnels and the operation of equipment, which is of great significance for construction risk warning and improving construction efficiency. To address issues such as incomplete detection of large muck blocks, missed detection of small muck blocks, and unclear edge segmentation during the segmentation process, a muck segmentation network based on global perception and edge refinement is proposed. A global perception module is designed to utilize deep strip convolutional attention networks of different sizes to expand the network's receptive field and enhance the integrity of muck block segmentation. An edge refinement module is introduced to aggregate spatial attention and channel attention, and a channel shuffle method is used to promote information exchange between different channels, thereby improving the network's perception ability for image details and the accuracy of muck edge segmentation. Through testing on a self-made dataset, compared with other classic algorithms, the proposed network achieves improvements in objective evaluation metrics, with recall, precision, intersection over union, and F1 score reaching 98.37%, 91.48%, 90.11%, and 94.80%, respectively. Additionally, the segmentation effect images are more complete, and the edges are clearer. 2024 Vol. 61 (3): 141-147 [Abstract] ( 144 ) [HTML 1KB] [ PDF 3774KB] ( 298 ) 148 Intelligent Image Analysis Algorithm for Advance Forecasting of Adverse Geological Bodies in Tunnels Based on Deep Learning JIANG Yuan WANG Hailin CHEN Zhao In response to the subjectivity and inefficiency issues in the analysis methods for advance forecasting images of adverse geological bodies in tunnels, this paper propose an intelligent image analysis algorithm called IR-TAG.This algorithm includes a feature encoding structure based on multi-cross attention, which effectively compensates for the inherent local induction bias of convolutional neural networks, making it difficult to fully extract global contextual information. Then, it introduces EffcinetNet-v2 as the backbone network, which has good classification performance and efficiency, to enhance the model′s ability to extract features of adverse geological bodies. The results show that in terms of detection accuracy, the mAP and F1 of IR-TAG are 84.09% and 83.63%, respectively, higher than other commonly used deep learning models. In terms of detection efficiency, IR-TAG has a smaller model size(73.5 MB) and faster image processing speed (38.87 f/s), making it suitable for intelligent and rapid detection of advance forecasting images of adverse geological bodies in tunnel construction. 2024 Vol. 61 (3): 148-156 [Abstract] ( 157 ) [HTML 1KB] [ PDF 9385KB] ( 478 ) 157 Study on Tunnel Traffic Flow Prediction and Lighting Regulation Based on GWO-LSTM Model DUAN Zhongxing DU Wanxin In order to solve the problem where the actual pavement brightness in highway tunnel does not automati? cally adapt to the traffic flow in dynamic traffic conditions and the traffic safety problem and lighting energy consumption problem arising from that problem, a dynamic lighting control method for middle section of tunnel has been devised based on traffic flow prediction. First, the traffic flow data measured at the Chatiaoling Tunnel in a time period is obtained and then preprocessed to generate the data sample required for training of the prediction model. Second, given the time sequence of the data sample, the traffic flow prediction model is devised based on the long short-term memory (LSTM) neural network, and the hyper-parameters of the LSTM network are optimized by using the grey wolf algorithm, so as to enhance the prediction accuracy of the network. Third, the parametric analysis of the key factors such as driving speed and traffic flow in the middle section of tunnel indicates that there is a strong correlation between traffic flow and pavement brightness. Based on that correlation, the lamp brightness regulation model is created. By using the LSTM traffic flow prediction model, advanced regulation inside the tunnel is achieved, so that the internal lighting can respond to the traffic conditions in a timely and effective manner. At last,tests are conducted to verify the effectiveness of the traffic flow prediction model and brightness regulation method that have been devised. As the results indicate, the method devised herein will guarantee adequate lighting in tunnel and also help with energy conservation. 2024 Vol. 61 (3): 157-165 [Abstract] ( 142 ) [HTML 1KB] [ PDF 3834KB] ( 575 ) 166 Visualization Simulation and Early Warning System for Shield Tunnelling Based on Digital Geological Model CHEN Youjian To achieve the comparison of shield tunnelling monitoring information and simulation data and safety warning under complex geological conditions, this study takes practical engineering projects as the research object.By digitizing the information of shield tunnelling objects and using BIM (Building Information Modeling) technology to establish a three-dimensional geological model, a set of shield tunnelling safety simulation and visualization monitoring early warning system is proposed based on the combination of BIM 4D model and finite element simulation model. Through color-coded warning and model visibility, the linkage between numerical model and geological model is realized, achieving the automation and precision of simulation warning. Practice has shown that this system can effectively solve the problem of simulation and optimization comparison of construction schemes, and has a good effect on rapid data processing and prediction of adverse trends. 2024 Vol. 61 (3): 166-174 [Abstract] ( 144 ) [HTML 1KB] [ PDF 5877KB] ( 392 ) 175 Study on Variation Regularity of Adhesion Strength of Cohesive Soil Considering Pressure and Temperature Effects YIN Yihao1 ZHONG Xiaochun2 HE Ziliang1 HUANG Siyuan2 HE Chunhao2 GAO Shijun1 ZHANG Jian2 In response to the common problem of cutter head clogging in cohesive soil layers during shield tunnelling, improvements were made to existing direct shear test devices. A controllable heating device was designed to investigate the variation regularity of adhesion strength of cohesive soil under different vertical pressures and interface temperatures, and the adhesion mechanism of clay was analyzed based on the water film theory. The results show that the adhesion strength of clay is determined by moisture tension, with greater moisture tension leading to higher adhesion strength of the soil. The main factors affecting moisture tension are the number of contact water rings, temperature, and matrix potential. The adhesion strength of test soil samples increases first and then decreases with increasing water content, reaching a peak value at approximately 25% water content. The influence of interface temperature on the adhesion strength of clay depends on the trends of changes in the number of contact water rings, temperature,and matrix potential. When the trends of weakening adhesion strength due to the number of contact water rings and temperature are greater than the trend of promoting adhesion strength due to matrix potential, the adhesion strength of clay decreases; conversely, when the trends are opposite, the adhesion strength increases. With the increase of vertical pressure, the adhesion strength shows a linear growth trend. 2024 Vol. 61 (3): 175-183 [Abstract] ( 144 ) [HTML 1KB] [ PDF 5430KB] ( 305 ) 184 Mechanical Response of Surrounding Rock and Supporting Structure Stress Characteristics in Deep-buried Soft Rock Tunnel: A Model Test Study SHU Zichen1 LIU Yang1 Based on the Chonggang Highway Tunnel in western Yunnan, this study conducts model tests on the me? chanical response of the surrounding rock and the stress characteristics of the supporting structure during the construction of a deep-buried soft rock tunnel. It analyzes the variation laws of surrounding rock pressure, anchor bolt axial strain, and steel arch axial strain at different distances from the excavation boundary during the three-bench construction of the tunnel. The results show that, as excavation progresses, the surrounding rock pressure at each measurement point exhibits a trend of "accumulation—release—stabilization". The surrounding rock pressure at the vault and shoulder is released quickly and significantly, while the pressure at the waist and foot is released slowly and slightly. As the distance from the excavation boundary increases, the surrounding rock pressure at the vault and shoulder can be divided into significant release zone, slow release zone, and relatively stable zone, with the signifi? cant release zone being about 0.55 times the tunnel diameter from the excavation boundary. Except for the shallow measurement point at the vault, all anchor bolt measurment points are under tension, with tensile strain less than the yield strain of the anchor bolt similar material, and the most unfavorable position is at the shoulder. The steel arch is mainly under compression, with the maximum compressive strain at the shoulder, but none reaches the yield strength of the steel arch similar material, and no adverse phenomena such as bending occur, indicating the safety of the supporting structure. 2024 Vol. 61 (3): 184- [Abstract] ( 133 ) [HTML 1KB] [ PDF 5947KB] ( 501 ) 194 Development and Application of Slurry Flow Model for Slurry Shield Tunnelling Based on BP Modified Rheological Model WANG Chengzhen1 DING Wantao2，3 YU Wenduan1 WANG Zhicheng1 SUN Tengyun1 WANG Zhongrong2 In order to improve the formation quality of filter cake in slurry shield tunnelling and maintain the stability of the excavation face, accurate prediction of the rheological characteristics of bentonite slurry is often required in the design of slurry parameters. Addressing the issues of numerical divergence and heavy reliance on empirical values in the solution process of slurry flow models for shield tunnelling, indoor rheological tests of slurry with different bentonite contents were conducted. Based on the experimental results, the Bingham-Papanastasiou (BP) modified rheological model was incorporated into the computational fluid dynamics (CFD) framework to develop an optimized numerical method for simulating slurry flow. The effectiveness and accuracy of this numerical method were validated by conducting numerical simulations of Poiseuille flow between parallel plates with Bingham fluids. Subsequently, a three-dimensional numerical model of slurry pipe flow was established to investigate the pipe flow characteristics of slurry under different rheological parameters. The results show that with the increase of bentonite content, the yield stress and consistency coefficient of the slurry exhibit an increasing trend. Moreover, an increase in rheological parameters leads to more energy loss of slurry during infiltration into the formation. As the consistency coefficient k increases from 0.1 Pa·s to 0.75 Pa·s, the pressure drop increases by 6.21 kPa, which can better maintain the effective transformation of slurry pressure and improve the formation quality of filter cake. 2024 Vol. 61 (3): 194-201 [Abstract] ( 145 ) [HTML 1KB] [ PDF 3122KB] ( 571 ) 202 Experimental Study on Diffusion Characteristics of WIS New Grouting Material in Tunnel Karst Conduit WANG Zhenjun1 ZHANG Qingsong2 HUI Bing1 LIU Rentai2 ZHANG Xu1 In order to explore the diffusion law of WIS new grouting material in tunnel karst conduit, a visualized simulation system for grouting in karst straight conduit was built based on the characteristics of water inflow in tunnel karst conduit. Orthogonal experiments were conducted to study the influence of pipe diameter, water flow velocity,and grouting rate on the diffusion and plugging distance of slurry under dynamic water grouting for three particle sizes of WIS new grouting material. The mechanism of slurry diffusion law under different slurry/water rate ratios (θ) was proposed. Typical conditions were selected to discuss the characteristics of grouting plugging body, and the dynamic evolution characteristics of multiple physical fields such as pressure field and velocity field during grouting diffusion process were compared and analyzed. The results show that the dynamic water flow velocity is the main external control factor affecting the diffusion and plugging distance of slurry. The plugging distance of slurry diffusion along the water flow direction within the effective diffusion range is negatively correlated with the slurry/water rate ratio θ.During the grouting diffusion process, the attenuation rate of dynamic water flow velocity and the rate of pressure increase show a slow-fast trend until plugging is achieved. Before the slurry is fully plugged, the dynamic water flow velocity decreases first and then increases, while the pressure increases first and then decreases. 2024 Vol. 61 (3): 202-211 [Abstract] ( 135 ) [HTML 1KB] [ PDF 3523KB] ( 301 ) 212 Study on Water Head Loss Pattern in Typical Stratigraphic Combination Structure in Xiamen LIU Zijian1 WANG Jia2 WANG Huayi1 ZHAO Cong2 WU Fan1 ZANG Wanjun3 During groundwater seepage in weakly permeable stratum, pore water pressure loss happens along the seepage path, and such loss is affected by many factors such as soil mass permeability coefficient, soil layer thickness and water head pressure. The model test on water head loss of composite stratum structure under different water head pressures has been conducted, to investigate how the pore water pressure is propagated in weakly permeable stratum. As the results indicate: In composite stratum structure, pore water pressure decreases as the soil layer thickness increases, pressure jump happens at the interfaces between the soil layers, and feeble confined water occurs in the highly permeable stratum; the water head loss is in positive correlation with water head pressure and soil layer thickness, but in negative correlation with the soil layer permeability coefficient; by using the test results, the relational expression for water head loss Δh, soil mass permeability coefficient, soil layer thickness and water head pressure has been established. 2024 Vol. 61 (3): 212-219 [Abstract] ( 132 ) [HTML 1KB] [ PDF 3989KB] ( 305 ) 220 Experimental Study on the Impact of Side Wall Coating on Luminous Environment of Highway Tunnel and Visual Characteristics of Human Eyes FENG Shouzhong1 ZHOU Long2 MAO Weixing1 LI Jie3 GAO Wei1 The priority in lighting design of highway tunnel is the pavement brightness in the tunnel, while the tun? nel side wall brightness is usually designed to be no more than 60% of the pavement brightness. Side wall is an important part of the luminous environment in tunnel, but its impact on the luminous environment in tunnel and the pavement lighting quality has not drawn much attention. Therefore this paper expounds an experimental study on the luminous environment in a tunnel that is illuminated by LED lights, and on the visual characteristics of human eyes,where the side wall of the tunnel is painted with energy-accumulating luminescent and white or grey coatings. As the study results indicate: With illumination by the same LED light, different types of coatings will bring different brightness levels of side wall. The wall surfaces painted with the energy-accumulating luminescent coating with 0.91 reflectivity and white coating with 0.97 reflectivity have greater brightness than the wall surface painted with the grey coating with 0.37 reflectivity. The brightness ratio between side wall and pavement of a tunnel can be 1.24~1.35. As the side wall brightness increases, the pavement brightness in tunnel and the visual distance of any obstruction on the pavement detected by human eyes will increase. If the pavement brightness remains essentially unchanged while the side wall brightness is changed in a tunnel, the power of the illuminating lamps can be reduced by 14.6% and 9.8% respectively in a tunnel with side wall painted with energy-accumulating luminescent coating and in a tunnel with side wall painted with white coating, as compared with a tunnel with side wall painted with grey coating; besides, the visual distance of any obstruction on the pavement in the tunnel detected by human eyes essentially remains unchanged, the variation pattern of the pupil diameter of the driver in a moving vehicle essentially remains the same, and the driver feels no discomfort. In the lighting design of tunnel, lighting energy conservation of a highway tunnel can be accomplished by painting the side wall with energy-accumulating luminescent coating or a coating with high reflectivity, and so reducing the power of the illuminating lamps. 2024 Vol. 61 (3): 220-227 [Abstract] ( 144 ) [HTML 1KB] [ PDF 3634KB] ( 597 ) 228 Analysis of the Impact of Urban Tunnel Midsection Ceiling Landscapes on Driving Safety Based on Visual Characteristics LIU Changbao ZANG Yanwei SUN Xing To analyze driving safety in the environment of urban tunnel ceiling landscapes, this study focuses on ur? ban tunnel midsection ceiling landscapes. Using 3DMax software, simulation models of tunnel ceiling landscapes with different colors and background patterns are constructed, and visual parameter data of drivers are collected through indoor simulation experiments. Based on the experimental data, the psychological workload and distraction level of drivers passing through different tunnel ceiling landscape environments are analyzed. Finally, the entropy weight method is utilized to evaluate different tunnel ceiling landscape schemes based on visual numerical characteristics. The experimental results indicate that setting up tunnel ceiling landscapes in the middle section of urban tunnels can effectively reduce the psychological workload of drivers. Design schemes with colors and patterns help alleviate the psychological workload of drivers. Urban tunnel ceiling landscapes do not significantly distract drivers,with the lowest distraction level observed under green, patternless designs. Overall, designs with color and patternless schemes exhibit higher driving safety than those with colored patterns and those without color or patterns. 2024 Vol. 61 (3): 228-235 [Abstract] ( 143 ) [HTML 1KB] [ PDF 4412KB] ( 468 ) 236 Study on Large Deformation Characteristics and Control Measures of Water-rich Phyllite Rock Tunnels CHANG Weixue1,2 LIANG Qingguo1 LI Qiwei1 FAN Chuntan1,3 WEI Jian4 Based on the Heimaguan Highway Tunnel in water-rich phyllite rocks, this study delves into the control technology for tunnel rock large deformation. Through analysis of the characteristics and causes of large deformation and failure, it is found that the complex geological tectonism in the tunnel area leads to the development of rock joints in the phyllite, and the migration of mineral components and free oxides in the joints further deteriorate the mechanical properties of the rock mass. Due to the strong sensitivity to water, the phyllite rock softens and disintegrates severely after long-term water immersion, resulting in low surrounding rock strength and susceptibility to large deformations in the tunnel. Field monitoring data analysis shows that the tunnel's large deformations exhibit significant asymmetry, and the deformations worsen after the excavation of the lower heading. Reinforcement measures such as sealing of groundwater, optimization of support parameters, and alternate construction of local double arch have been carried out to deal with the large deformation section in the water-rich phyllite rock tunnel. The results indicate that using the construction technology of discharging and sealing water as well as alternative construction of double-layer arch can effectively control the asymmetric large deformations caused by softening of the phyllite rock by long-term water immersion and it is more convenient and economical. 2024 Vol. 61 (3): 236-244 [Abstract] ( 146 ) [HTML 1KB] [ PDF 6449KB] ( 336 ) 245 Application of Active Support Technology for Large Deformation in Haidong Soft Rock Tunnel YANG Zhaofeng1 WANG Bo2 DU Yongquan1 HUANG Changkuan1 FAN Yong1 Based on the Haidong Tunnel of the Central Yunnan Water Diversion Project, the adaptability of active support technology was studied in the upstream 100 m section of soft rock with large deformations in Branch Tunnel3. Through on-site tensioning tests, loosening ring tests, and phased implementation, parameters were continuously optimized and adjusted. The control deformation effect, improvement of construction progress, and existing problems were analyzed and evaluated. Finally, design parameters for active support under similar geological conditions and dynamic adjustment principles were summarized. The study shows that after the application of active support technology in the test section of the tunnel, both vertical settlement and horizontal convergence are controlled within 20cm. The excavation advance rate increased from 15 m per month to 45 m per month. Active support technology has a good application effect in controlling deformation in hydraulic tunnels and improving work efficiency. 2024 Vol. 61 (3): 245-252 [Abstract] ( 156 ) [HTML 1KB] [ PDF 3922KB] ( 432 ) 253 Study on Mechanism and Prevention of Slope Instability at Shallow-buried, Bedding and Unsymmetrically Loaded Tunnel Portal ZHAO Haisong WEI Anhui SHAO Jiang XIANG Bo WU Kai LI Shiqi ZHOU Renqiang LIU Song Understanding the evolution mechanism of slope instability at the bedding and unsymmetrically loaded tunnel portal and studying the relationship between slope retaining structure stress and tunnel burial depth is crucial for slope protection. During the construction of the Shiliangzi Tunnel, the slope instability and failure occurred at the shallow-buried, bedding and unsymmetrically loaded tunnel portal. Geological mapping, borehole drilling,surface displacement monitoring, numerical simulation, and other methods were used to clarify the slope structure,physical-mechanical parameters, and deformation characteristics. Based on this, the instability mechanism of the slope at the tunnel portal was analyzed, the protection methods and measures for the slope at the bedding and unsymmetrically loaded tunnel portal were studied. Results show that the instability evolution of the slope at the shallowburied, bedding and unsymmetrically loaded tunnel portal goes through four stages: 1) reduction of interlayer shear strength, 2) formation of bedding and unsymmetrical loading, 3) local failure of lower slope body leading to retrogressive creep and cracking of back slope, 4) exacerbation of deformation leading to thrust load-caused failure of the slope at the tunnel portal . With the installation of anti-slide piles and a tunnel burial depth of 16 m on the mountain side, the slope stability is achieved. At this depth, control over landslide deformation and pile shear force is significant. However, the effectiveness decreases significantly when the burial depth exceeds 16 m. 2024 Vol. 61 (3): 253-265 [Abstract] ( 147 ) [HTML 1KB] [ PDF 13419KB] ( 559 ) 266 Analysis on the Vibration Influence on Upper Buildings Induced by Cutting of Pile Group by Extra-large-diameter Shield in Dense Urban Areas CHEN Yifan1 HUANG Shuhua2 SHEN Xiang1, 3, 4 SHENG Jian2 CHEN Xiangsheng1, 3, 4 ZHANG Liang2 Construction of a shield tunnel in a central urban area will inevitably encounter the pile foundations of existing buildings or structures, but direct cutting of the pile foundation will impose enormous risks. In order to further reveal the internal mechanism of cutting of pile foundation by a shield, the case of the Haizhu Bay Tunnel cutting through the foundation of CNNC Business Building is used as an example in this study. The field measured vibration data is used to analyze the pattern of the vibration response of CNNC Business Building induced by the shield grinding the pile foundation, and to investigate the tilt of the building caused by the shield grinding the pile foundation. As the study results indicate: The building mainly experiences vertical vibration when the shield grinds the pile foundation. Inside the building, the vibration is quickly attenuated as its propagation distance increases, so the vibration induced by shield construction impacts only a small area. The area in 2/3D (D is the shield diameter) with the tunnel center line being the axis is the key impact area. As indicated by the monitoring results, the vibration catastrophe amplitude of the first floor, which is closest to the shield tunnel, is over 2 times the vibration catastrophe amplitude of the second floor. According to the study, the vibration amplitude will indicate the direction of tilt of the building, so the direction of tilt of the building can be analyzed by monitoring its vibration variation. 2024 Vol. 61 (3): 266-275 [Abstract] ( 134 ) [HTML 1KB] [ PDF 9423KB] ( 403 ) 276 Study on Impact Zoning Method and Zoning Control Technique for Construction of Large-diameter Shield Tunnel Adjacent to Viaduct Pile Foundation Group GE Zhaoguo In order to investigate the impact zoning for large-diameter shield tunnel adjacent to viaduct pile founda? tion group and propose effective comprehensive control measures, the shield construction adjacent to viaduct pile foundation group in the Qibaoshan Station-Huajing Station interval in the Shanghai Airport Link Project is used as an example in this study, and numerical simulation and theoretical analysis are conducted to devise the adjacent impact zoning method. Numerical simulation and field test are conducted to investigate the control result and effectiveness of the zoned reinforcement scheme. The following conclusions are drawn: (1) The adjacent impact zoning method devised based on horizontal adjacent degree and vertical adjacent degree can be used for adjacent degree analysis of pile foundation group. (2) The combined reinforcement method of MJS reinforcement +isolation pile + sleeve valve pipe grouting below pile cap is proposed for strong impact zone, while the zoning control by isolation pile is proposed for weak impact zone. (3) The isolation pile is mainly meant to isolate the horizontal deformation of soil mass, while the MJS reinforcement and grouting below pile cap are mainly meant to reinforce the soil mass and minimize the looseness and slippage of soil mass induced by excavation. (4) The zoning control technique can reduce overall settlement of pile cap by 50.4% and its horizontal displacement by 69.7%, and reduce overall settlement of pier column by 47.7% and its horizontal displacement by 56.0%; the tilt of pier column is kept within 37.1%~46.9%. 2024 Vol. 61 (3): 276-289 [Abstract] ( 152 ) [HTML 1KB] [ PDF 10489KB] ( 363 )

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