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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2021 Vol.58 Issue.5 Published 2021-10-25 1 A Review of Model Test Studies on the Impact of Shield Construction on Adjacent Tunnels WEI Gang1,2 ZHAO Deqianlin1 HUANG Rui1 During the construction of new shield tunnels adjacent to existing tunnels, the shield construction will cause deformation and damage to adjacent existing tunnels, the impact of shield construction on adjacent tunnels has become an urgent issue to be resolved, and model test is an important method to study this topic. This paper categorizes existing model tests into indoor scale tests and centrifugal tests. And then it studies different crossing and parallel construction methods, summarizes the impacts of shield construction on existing tunnels under different factors such as thrust, tunnel spacing, and crossing sequence, etc. Finally it compares existing tests and proposes further research ideas and directions, which shall provide a reference for future model test studies. 2021 Vol. 58 (5): 1-8 [Abstract] ( 1295 ) [HTML 1KB] [ PDF 1541KB] ( 2261 ) 9 An Outlook for Researches on the Impact and Control Technology of Shield Construction in Gassy Soils DING Zhi1,2 HE Chenyang1 ZHANG Xiao1 ZHANG Wenhong3 WU Sheng4 Gassy soils will be inevitably encountered in the shield construction, and shallow gas in gassy soils can have a huge impact on the shield construction process and pose serious hazards to construction workers. After summarizing the types of gassy soils, the pressure of shallow gas, the buried depth and gas composition in various regions of China, it is found that most are dominated by CH4 gas generated by the decomposition of organic matters,with slightly different causes. Based on analysis on existing disaster cases, it illustrates the engineering influence of shallow gas in gassy soils, the impact of controlled gas release, and the influence of matric suction. The results show that gassy soil is a special unsaturated soil, and its shear strength and soil deformation are influenced by the matric suction. At the same time, the uncontrolled or controlled release of shallow gas will cause different degrees of disturbance to the surrounding soils, while the engineering solutions are mostly based on pre-controlled gas release. Some effective measures are presented, which can eliminate the hidden hazards of harmful gas in gassy soils to the construction of subway tunnels. 2021 Vol. 58 (5): 9-20 [Abstract] ( 812 ) [HTML 1KB] [ PDF 2777KB] ( 1995 ) 21 Prediction of Shield Construction Risks in Subway Tunnelling Based on Fault Tree and Bayesian Network ZHANG Longguan1 LIU Suimei1 LI Kaifu1 XU Jin2,3,4 WANG Shengnan3,5 LI Qiang3 At present, in the process of subway shield construction in China, risks and accidents occur frequently, and it has become important tasks in shield construction risk management to predict the occurrence trend of shield construction risks and improve the accuracy of risk response. This paper designs an effective method for prediction of shield construction risks and its development trends according to the alarm data of shield machines. Firstly, the fault tree method is used to identify the correlation between major shield construction risks and the fault alarm data of shield machines; then, on the basis of this, a risk prediction model based on Bayesian network is established, and the backward diagnostic inference technique of Bayesian network is applied to calculation of the maximum possible path to identify key shield failures that lead to risk events, so that subsequent risks could be strictly controlled in case of such failures; finally, a subway project is used as an example to verify the reliability and applicability of the method. The studied method and model can be embedded in various types of shield construction risk management systems to provide risk warning support to construction sites. 2021 Vol. 58 (5): 21-29 [Abstract] ( 827 ) [HTML 1KB] [ PDF 5387KB] ( 1703 ) 30 Study on Anti-Freezing Parameters of High-Altitude Tunnels in Western Sichuan Based on Field Tests ZHENG Bo1,2 WU Jian1,2 ZHENG Jinlong3 KUANG Liang4 GUO Rui1,2 In view of design parameters of anti-freezing and thermal insulation for high-altitude tunnels in West? ern Sichuan Plateau, based on the measured longitudinal temperature data of 10 typical high-altitude tunnels in Western Sichuan, this paper studies the longitudinal temperature characteristics and anti-freezing parameters of high-altitude tunnels in Western Sichuan. The research results show that the longitudinal temperature distribution inside operational tunnels on the Western Sichuan Plateau can be divided into three types: cut-through, weakly symmetrical and asymmetrical; the longer the length of high-altitude tunnels is, the greater the temperature difference between the tunnel portal and the tunnel inside will be in winter season, and the maximum temperature difference inside and outside tunnels in winter is linearly related to the length of the tunnels on the Western Sichuan Plateau;based on the temperature data measured at tunnel portals, this paper puts forward an empirical formula for calculation of the thickness of the thermal insulation layer laid at tunnel portal sections on the Western Sichuan Plateau;combined with parameters such as air temperature and winter wind speed at the portal, this paper conducts a comprehensive analysis of the length of the thermal insulation layer setup at the tunnel portal sections and proposes the empirical formula for calculation of the length of thermal insulation layer laid at the portal sections of long or extralong tunnels on the Western Sichuan Plateau; in terms of the design of the thermal insulation layers at the portal sections of tunnels on the Western Sichuan Plateau, dynamic design methods shall be adopted, and if conditions permit,it should be amended according to the measured longitudinal temperature data after completion of tunnel construction. 2021 Vol. 58 (5): 30-36 [Abstract] ( 701 ) [HTML 1KB] [ PDF 1470KB] ( 1135 ) 37 tudy on the Control Measures against Ground Settlement Induced by Shield Tunnel Construction underneath Railway Throat in Sandy Cobble Stratum QIU Wenge WAN Shifu GAO Ganggang ZHAO Hailin QI Xingxin Sandy cobble stratum has little cohesion and poor self-stability capacity, and is very prone to collapse during tunnel construction, making it difficult to control the ground surface settlement. In order to study the ground surface settlement pattern and relevant control measures when a shield is driving under sensitive areas in sandy cobble stratum, this paper uses the Chengdu Metro Line 5, which passes under the throat area of Baocheng Railway, as the engineering context for the study. Through comparison of construction methods, numerical simulation and feedback from site monitoring, this paper proposes the control measures for and elucidates the pattern of the ground settlement, and verifies the effectiveness of the settlement control measures. The study results show that it is reasonable and effective to use the reinforcement measures such as the double-layered large pipe roof in combination with the ground tracing grouting method to control the ground settlement during the shield construction in sandy cobble stratum; calculations show that the ground surface settlement is reduced by 61.16% after consolidation of the strata compared to that without consolidation; using fully automatic monitoring system for real-time feedback and early warning of ground settlement, the monitoring data show that the maximum ground settlement during construction is 1.29 mm and the maximum heaving is 0.72 mm, which verifies the effectiveness of the ground reinforcement measures and ensures the safety of shield tunnelling and railway operation. 2021 Vol. 58 (5): 37-45 [Abstract] ( 595 ) [HTML 1KB] [ PDF 3426KB] ( 1519 ) 46 On Defects and Disaster-causing Factors in Tunnelling in Salt Rocks WANG Zhijie1 LI Jinyi1 DENG Yuhang1 DU Yiwen1 ZHOU Ping1 BAI Xiaoke2 LI Fenggang2 The Friendship tunnel on China-Laos railway is located in salt rocks, where very serious tunnel defects are encountered during construction. Therefore, it is of great significance to study the causes of the defects for the subsequent construction. In view of this, the investigation is carried out at the Friendship tunnel site to reveal construction defects and deeply study the disaster-causing factors by means of on-site sampling, indoor test, on-site monitoring and theoretical analysis, etc. It is found that lining cracks and excessive deformations are caused by water solubility and expansibility of salt rocks; tunnel collapse, cavity, corrosion and crystallization are caused by water solubility and corrosivity of salt rocks. Invert heave is caused by uneven settlement, salt recrystallization and rheology of weak surrounding rocks. Mechanical properties and water solubility of salt rocks, salt rock percentage, underground water composition and content in excavation section are main reasons for construction disasters of salt rock tunnel. Such combined measures as strengthening drainage, using multi-layer waterproofing structure, optimizing building materials, increasing structural corrosion resistance and implementing double-layer initial support and base replacement can be used as important measures for rapid and safe construction of salt rock tunnels. 2021 Vol. 58 (5): 46-55 [Abstract] ( 648 ) [HTML 1KB] [ PDF 5279KB] ( 1251 ) 56 Research on the Routing Scheme of a Double Shield TBM Passing through the Metro Station GAO Xin WANG Wenjuan LI Qingfei FENG Shijie WU Qi Double shield TBM has been widely used in urban rail transit projects for its advantages of safe, effi? cient and fast construction, and a reasonable routing for TBM passing through the station is also one of the key technologies for TBM tunnel construction. Based on the equipment models and station-crossing methods commonly used for double shield TBM construction in Qingdao, this paper conducts a thorough research and analysis on the different TBM station-crossing methods, the relationship between routes and construction clearances, furthermore assesses the construction risks for tunnels with small clear distance. The conclusions are drawn as follows: (1) the engineering cost performance is the highest when priority is given to the method of whole TBM machine curved passing through the station, and the crossing route is two section of reverse curves tangent to each other, with equal radius and the radius of R=350 m; (2) when the TBM passing through the station installed with the secondary lining, the construction clearance of the mined approach tunnel is the same, and the deflection route length increases with the increase of the deflection radius; (3) when the TBM passing through the station installed with the initial support, the length and construction clearance of the mined approach tunnel decrease with the increase of the sidewall thickness, and when the sidewall thickness is close to 1.15 m, priority should be given to the method of whole TBM machine straight passing through the station; (4) taking the common medium-weathered and slightly weathered strata in TBM tunnelling as examples, the plastic zone of the rock pillar sandwiched by the mined approach tunnels is not yet connected, and the horizontal convergence is small, so the construction risk of tunnels with small clear distance can be controlled, and the construction safety can be achieved; (5) it is recommended that priority be given to the method of TBM passing through the station install with the secondary lining, with strict control of the posture and direction of the TBM in the reverse curve section, timely and reasonable correction of the deflection, and ensuring the safety margin reserved between the cutter head and the structure. 2021 Vol. 58 (5): 56-64 [Abstract] ( 624 ) [HTML 1KB] [ PDF 4931KB] ( 1123 ) 65 Analysis on Seismic Response of Shield Tunnels Passing Through Soil-Rock Strata LI Siming1 YU Haitao2 XUE Guangqiao3 XU Lei4 When a tunnel passes through soil-rock strata, it is the key controlling link for the seismic design of the structure. In order to explore the aseismic safety of a shield tunnel passing through strata with varying stiffness, taking a shield tunnel project in Nanjing as the background, a 3D finite element model of shield tunnel-strata is established considering the characteristics of soil-rock varying strata. Then, the dynamic time history analysis method is adopted to study the seismic response law of the shield tunnel passing through soil-rock strata. The results show that the acceleration and displacement responses of strata and tunnel are significantly different in soil-rock interface section, soil section and rock section under the same buried depth condition; as for the seismic wave, the spectrum amplification effect of the tunnel and the strata in the soil-rock interface presents much more the spectrum characteristics in harder rock stratum; when the ground motion is input parallel to the tunnel axis, the peak values of internal force and deformation response in the shield tunnel structure occur at the soil-rock interface, the abrupt change of stratum stiffness leads to significant amplification of seismic response of the tunnel structure passing through the stratum, which should be specially paid attention to in the seismic design. 2021 Vol. 58 (5): 65-72 [Abstract] ( 595 ) [HTML 1KB] [ PDF 4343KB] ( 1126 ) 73 Study on the Effect on Deformation of the Surrounding Rock Induced by DeepBuried Tunnelling under Hard Rock Combination Conditions CHANG Gang1,2 PAI Lifang3,4 PANG Weijun1,4 WU Honggang1,2,4 YAN Lizhen1 When a tunnel is located in deep-buried bedding hard rock structures, the rock deformation and failure caused by the stress redistribution have a certain level of particularities due to their stratification characteristics and structural forms. This paper takes the Huangcao tunnel on a certain high-speed railway as the engineering case,studies the distribution of the secondary stress field in the surrounding rock affected by excavation through numerical calculation, mainly taking into consideration the influence of hard rock bedding and joints, and evaluates the deformation of the surrounding rock accordingly. The results show that (1) when considering the interaction of bedding and conjugate joints in deep-buried tunnels, the primary and secondary deformation displacements are not obvious in terms of the direction, while the circumferential displacement is featured by asymmetric distribution; (2) the greater is the tunnel depth, the greater the deformation displacement of the tunnel walls will be under excavation conditions, and the maximum deformation and contour range are developed in the direction of the vertical plane; (3) the presence of conjugate joints greatly reduces the asymmetric deformation features of rocks in bedding tunnels; (4) under the impact of horizontal tectonic stress fields, larger deformation displacement is generated in the tunnel walls in the direction of the maximum horizontal principal stress. 2021 Vol. 58 (5): 73-77 [Abstract] ( 573 ) [HTML 1KB] [ PDF 3270KB] ( 1267 ) 78 Research on the Wear Prediction of Disc Cutters Based on BP Neural Network CHEN Yukun1 GUAN Huisheng1 ZHOU Lei2 LIU Cheng1 The accurate prediction of disc cutter wear is essential to prevent excessive wear of disc cutters on the full-face tunnel boring machine and to reduce costs on cutter tool repair and maintenance. Based on the abrasive wear mechanism and the disc cutter force model, this paper derives a mathematical model between the radial wear of the disc cutter and the penetration, installation radius, rotation speed of the cutter head; and it establishes a prediction model for the radial wear of the disc cutters based on the BP neural network, which is optimized by using the genetic algorithm (GA) and particle swarm optimization (PSO), respectively. The prediction model is verified by a TBM tunnelling project case in Nortwest China, and the results show that the radial wear of the disc cutters can be predicted more accurately by using the thrust of the TBM, the installation radius of the disc cutters and the rotation speed of the cutter head as the input nodes of the neural network, with higher prediction accuracy. Finally, it designs the human-computer interface for the GA-BP neural network based prediction model by using a hybrid programming method of MATLAB and C#. 2021 Vol. 58 (5): 78-84 [Abstract] ( 558 ) [HTML 1KB] [ PDF 2041KB] ( 997 ) 85 On Parameter Optimization for a Slurry Shield Approaching Construction under Existing Subway Tunnels in Water-Rich Pebble and Mudstone Composite Stratum SONG Yang1 WANG Weiyi2 DU Chunsheng3 Due to the rapid development of urban rail transit, the situation where new tunnels passing under exist? ing tunnels at a close distance is inevitable, and the risk control is mainly achieved by controlling the driving parameters. Based on the running tunnel section between Xiuling Road Station and Mingxiu Road Station of Nanning Metro Line 5, this paper analyzes and optimizes the driving parameters through laboratory similarity tests, and establishes a folded wedge model being applicable to the upper-soft and lower-hard composite stratum, finally it conducts a comparative study regarding the driving parameters of the slurry balance shield in the full-face mudstone strata as well as in the pebble and mudstone composite strata. The study results show that it is technically feasible to optimize the driving parameters by using the control variable method through laboratory similarity tests; compared with conventional models, the hypothesis that the failure surface is approximately assumed as a folded line, is more suitable for the deformation and failure modes of the upper-soft and lower-hard composite stratum; the driving parameters fluctuate in a wide range when the slurry shield in full-face mudstone strata, with the cutterhead torque and total thrust being particularly pronounced. 2021 Vol. 58 (5): 85-95 [Abstract] ( 577 ) [HTML 1KB] [ PDF 5295KB] ( 1087 ) 96 Study on Measured Torque Parameters of Large-Section Rectangular EPB Pipe Jacking Machine with Multiple Cutterheads XU Youjun1,2 HUANG Zhengdong1,2 ZHANG Xu1,2 ZHANG Chao1,2 KANG Jiawang1,2 ZHOU Wei1 A rectangular pipe jacking machine is usually equipped with multiple cutterheads to cut and jack the soil mass on the excavation face by zoning. The torque setting parameters of cutterheads in different positions directly affect the excavation efficiency and safety of rectangular pipe jacking machines. Taking the pipe jacking construction of the Jingsan Road underground utility tunnel in Baotou as the engineering background, this paper uses various methods such as theoretical analysis and field measurement to study the changing pattern of the measured torques of cutterheads in different positions and the relevant torque settings during the jacking process. The conclusions are drawn as follows: the friction between the cutterhead and the soil mass mainly affects the torque of the cutterhead;the measured torque values of the cutterheads are close to the calculated values, and the former fluctuates dynamically with the jacking distance; the torques of three groups of cutterheads are of different values, of which the torque of the No.1 central large cutterhead in the first group is the largest, while that in the third group is the second and that in the second group is the smallest; the rated torque value of the No.1 central large cutterhead in the first group is about 1.36 times the measured torque value, while that of the small cutterheads in the second group is about 3.11 times the measured value, and that of the small cutterheads in the third group is about 2.8 times the measured value.The safety reserve setting of the rated torque value of the small cutterheads is quite high, and optimization could be achieved by appropriately reducing the rated torque value of the small cutterheads. 2021 Vol. 58 (5): 96-103 [Abstract] ( 545 ) [HTML 1KB] [ PDF 2587KB] ( 897 ) 104 Field Test Research on the Contact Pressure and Stress Characteristics of Jacked Steel Pipes with Deep-buried Depth and Large-section PAN Weiqiang1 JIAO Bochang2 LIU Xian2 ZENG Hua3 JI Maojie3 In order to study the spatial distribution and variation pattern of the external load of deep-buried over? sized-section steel pipes in pipe jacking construction, the effect of grouting load and the structural stress characteristics, etc., taking the tunnel project of Jing'an Temple Station of Shanghai Rail Line 14, which is constructed by pipe jacking method, as the research context, this paper carries out field monitoring and tests by using water and soil pressure gauges and strain gauges, and followed by collection, processing and analysis of the external load and structural strain data. The research results show that under the steady load condition, the circumferential distribution of the external load of the pipe segment is generally in pear-shape, while the measured values of the total soil and water pressure at the top of the pipe segment is basically consistent with the theoretical values; grouting loads during construction can be counted as 1 time the total stable pressure at the top; the latticed steel pipe segment still conform to the plane section assumption; the internal force transfer between the pipe segments has a large impact on the circumferential stress and strain, and the longitudinal force at the pipe segment ring joint affects the stiffness of the ring joint, which in turn affects the internal force transfer coefficient; the incidental ground load causes a great increment in the external load of the structure but a small increment in the strain of the structure. 2021 Vol. 58 (5): 104-113 [Abstract] ( 583 ) [HTML 1KB] [ PDF 4145KB] ( 968 ) 114 Study of the Optimization of Air Curtain Parameters in Tunnelling Based on Orthogonal Simulation Test CHEN Zhiying NIU Guoqing WANG Shumeng GUO Chenwei Based on an orthogonal test design, and taking a tunnel in Wuhan City as the study subject, this paper uses the FDS numerical simulation software to study the influence induced by the change of air curtain parameters on the smoke prevention effect during tunnel fire, determines the significant degree of each factor to smoke prevention effect by range analysis and variance analysis, eventually obtains the optimal combination of air curtain parameters. The results show that: the installation of air curtains in the tunnel has a significant smoke control effect, of which jet width has the greatest impact on the ambient temperature and visibility for the evacuation of tunnel personnel, followed by the jet angle; the jet width has the greatest impact on the smoke prevention efficiency of the air curtain while the jet velocity comes second. Through a comprehensive analysis of the three characteristic indicators, i.e. evacuation ambient temperature, visibility, air curtain smoke prevention efficiency, this paper finds that when the firepower is 20 MW, the optimal combination of the tunnel air curtain is jet speed of 30 m/s, jet angle of 20°, jet width of 0.4 m, and air curtain spacing of 60 m. With the adoption of the optimized solution, the ambient temperature for tunnel evacuation is lower than 60 ℃, while the visibility is higher than 20 m, and the smoke prevention efficiency is as high as 97%, meeting the requirements for personnel evacuation in case of fire. 2021 Vol. 58 (5): 114-121 [Abstract] ( 563 ) [HTML 1KB] [ PDF 1458KB] ( 1077 ) 122 Study on the Influence Pattern of Seepage Field on Temperature Field in the Construction of the Metro Cross Passage by Freezing Method in Water-Rich Strata PAN Xudong1 BAI Yunlong1 BAI Yunfei2 ZHANG Zhiqiang2 LIAO Lin1 Based on the hydro-thermal coupling theory, this paper establishes a numerical model for single-row freezing pipes to study the influence pattern of the seepage field on the temperature field under different water head differences in the freezing process, as well as a numerical model for multi-row freezing pipes to optimize the freezing effect because of the deficiency of freezing effect of single-row freezing pipes. Finally the numerical simulation results are applied and verified in the construction of a cross passage of Taiyuan subway project. The results show that the influence of groundwater seepage on the temperature field has a hysteresis effect along the seepage direction; during the freezing process the seepage field has the most significant effect on the upstream freezing effect, and using the single-row freezing pipes it cannot effectively reinforce the strata in a timely manner; under the same freezing conditions, arranging freezing pipes densely around the cross passage can advance the closing time of freezing wall by 43 d and increase the thickness of the upstream freezing wall by 0.7 m. The application effect in the actual engineering shows that using the multi-row-pipe freezing method no water inflow or sand gushing phenomenon is observed, thus achieving the purpose of ground freezing and reinforcement. 2021 Vol. 58 (5): 122-128 [Abstract] ( 609 ) [HTML 1KB] [ PDF 3926KB] ( 1070 ) 129 Model Test Study on Distribution Characteristics of Longitudinal Temperature Field in Tunnels in Cold Regions GUO Rui1, 2,3 ZHENG Bo2, 3 FANG Lin1, 4 WU Jian2, 3 As for the distribution law and influencing factors of longitudinal temperature field in tunnels in cold re? gions, an indoor model test device is developed to analyze the effects of tunnel length, temperature and air velocity at the tunnel portal on distribution of longitudinal temperature field in tunnels in cold regions. The results show that the influence of tunnel length on longitudinal length under negative temperature is smaller when the air velocity at the tunnel portal is smaller and the temperature at the portal is higher; the longitudinal length under negative temperature in the tunnel increases linearly as a function of tunnel length when the air velocity at the tunnel portal exceeds a certain critical value and the temperature at the portal is lower than a certain critical value; the influence of the temperature at the portal on the longitudinal length under negative temperature in the tunnel is smaller when the air velocity the tunnel portal is higher and the tunnel length is shorter; under a certain air velocity at the tunnel portal, the longitudinal length under negative temperature in the tunnel increases linearly along with the decrease of the temperature at the portal when the tunnel length is long enough. The relationship between the longitudinal antifreezing fortification length and the air velocity at the portal follows a power function. The influences of temperature and air velocity at the portal on temperature field in tunnels in cold regions are promoted and strengthened with each other. The order of sensitivity of each factor to the longitudinal temperature field in tunnels in cold regions is: air velocity at the portal > air temperature at the portal > tunnel length. For a specific tunnel in cold regions, various factors should be comprehensively considered, and specific analysis should be made in terms of the anti-freezing design. 2021 Vol. 58 (5): 129-139 [Abstract] ( 603 ) [HTML 1KB] [ PDF 6830KB] ( 967 ) 140 Study on the Occurrence Characteristics and Drainage Tests of Shallow Natural Gas in High-Gas Bearing Tunnels in Non-Coal Measure Strata TANG Ouling1 CHEN Xinghai1 CHANG Xingwang1 SU Peidong2 Certain sections in the running tunnel between the New Warf Street Station to Honglian Village South Station of Chengdu Rail Transit Line 19 Phase II Project are high-gas bearing tunnels. In order to study the spatial distribution characteristics, recharge mode and fugitive pattern of gas in high-gas bearing strata, this paper uses test methods, such as stratified detection, fugitive gas monitoring and borehole drainage, etc., to analyze whether the gas concentration in tunnels can be reduced in advance through ventilation and drainage, with the aim to provide technical support for the design and construction of tunnels in high-gas bearing sections. The test results show that the gas in the strata of the studied area mainly accumulates in the form of gasbags, which are recharged from the lower Sumatou gas field through faults; the option to reduce the gas concentration in the tunnels in the studied area through ventilation and drainage measures is feasible, with a maximum impact radius of 5 m for the drainage boreholes. 2021 Vol. 58 (5): 140-146 [Abstract] ( 562 ) [HTML 1KB] [ PDF 4526KB] ( 1182 ) 147 Experimental Study on the Mechanical Behaviors of the Lining Structure Affected by Grouting in Tunnel Secondary Lining Cavities through Molds LI Fuhai1 LI Rui1 JIANG Yilin1 GAO Hao1 WANG Yibin1 WANG Peixun2 The existence of many cavities behind the tunnel secondary lining will lead to the deterioration of the structural stress conditions, which could easily cause tunnel lining cracking and even directly affect the operation safety of tunnels. In this context, the method of grouting through molds is widely used at construction sites to fill the cavities. In order to study the changing pattern of the bearing capacity of the lining structure during the grouting via molds, aiming at elimination of cavities behind tunnel secondary lining, the lab model tests are conducted with geometric similarity ratio of 1∶30, in combination with the engineering condition of a railway tunnel which uses microexpansion materials for grouting and reinforcement of secondary lining cavities, and the force distribution pattern and characteristics of the initial support and the secondary lining are studied in terms of grouting and reinforcement at different cavity locations behind the secondary lining with high-performance micro-expansion filling materials. The results show that the bending moment at the cavities grows fastest, and the growth of the bending moment in the secondary lining is greater than that of the initial support, with the most obvious growth at the cavities of the vault and the cavities of the double-arch shoulder; the axial force at the cavities grows fastest and changes most significantly at the top of the arch and the right arch shoulder. The internal force changes of the structure caused by the filling materials during the grouting process are within the specified range and no cracking is found, which effectively verifies the application safety of the self-developed cement-based filling materials. 2021 Vol. 58 (5): 147-158 [Abstract] ( 598 ) [HTML 1KB] [ PDF 7868KB] ( 910 ) 159 Laboratory Experimental Study on the Wear of EPB Shield Cutting Tools in Sandy Stratum CHEN Yan1 WANG Yuhao1 FANG Yong1 XU Gongyun1 ZHOU Kaige1 LIU Sijin2 In order to explore the wear law of earth pressure balance (EPB) shield cutting tools, indoor tests are car? ried out with self-made test equipment simulating the shield driving process, and the rules of the influence of installation orientation, quartz particle content and conditioner content on cutter wear are analyzed by means of microscopic observation and statistical analysis of wear-induced mass loss. The results show that: in the wear process of cutters, the installation orientation of cutters affects the wear condition; there is a positive correlation between the surface wear form, the wear-induced mass loss and the installation radius, the quartz particle content; and adding conditioner can effectively reduce the wear-induced mass loss of cutters and mitigate the development of cutter surface wear. In view of the above rules, the Rabinowicz micro-cutting model is modified, by which the correction coefficient of cutting direction and the reduction coefficient of conditioner are introduced to consider the wear difference between the front and back of cutters as well as the influence of ground pre-treatment respectively, and the abrasive wear coefficient is analyzed in detail to obtain the modified prediction formula of cutter wear-induced mass loss of EPB shields, which can provide reference for related research and practical engineering. 2021 Vol. 58 (5): 159-166 [Abstract] ( 517 ) [HTML 1KB] [ PDF 3190KB] ( 842 ) 167 Experimental Study on Caulking Treatment Against Water Leakage in Shield Tunnel Segment Joints LI Yi1,2 DING Wenqi1,2 YANG Linsong3 XIE Dongwu1,2 To explore the effect and applicability of the caulking treatment measures against water leakage in shield tunnel segment joints, investigation and statistics are carried out on the segment water leakage conditions in a shield tunnel project in China. And with prepared concrete specimens the three-dimensional water pressure loading test system independently developed by Tongji University is used to carry out multiple sets of laboratory experimental study on the caulking and sealing method — the water leakage treatment measure actually used in the project.The results show that: (1) using the EPDM caulking and sealing gasket to treat the water leakage in segment joints, it can meet the requirements for Class I water-proofing. When the opening is 3 mm and the dislocation is 0 mm, it has a waterproof capacity of 0.38 MPa. When the dislocation is large, optimization design needs to be made for the section structure of the sealing gasket; (2) the sealing performance of the segment joint has obvious influence on the treatment effect of the caulking and sealing method, and water leakage is more likely to occur at positions where the caulking and sealing gasket is extruded out in the extrusion process and the sealing performance of the segment joint is poor. 2021 Vol. 58 (5): 167-172 [Abstract] ( 526 ) [HTML 1KB] [ PDF 2195KB] ( 786 ) 173 Application of Rayleigh Wave Method in Detection of Invert Thickness of Railway Tunnels LI Bo ZHOU Bin FENG Jianjun Tunnel invert is the main structure bearing the train load, and its insufficient thickness is one of the more serious defects in railway tunnel quality detection. Therefore, in view of the shortcomings of the common core drilling method and geological radar method in detection of tunnel invert thickness, and based on the dispersion characteristics of Rayleigh wave, the experimental study is carried out for the application of Rayleigh wave method in detecting invert thickness of railway tunnels. Some suggestions are put forward in terms of the relevant parameters of the observation system and the parameters of excited dominant frequency of the receiving system, to achieve accurate quantitative detection of the tunnel invert thickness, and the accuracy of the detection results of the Rayleigh wave method is verified by drilling holes. 2021 Vol. 58 (5): 173-178 [Abstract] ( 483 ) [HTML 1KB] [ PDF 1755KB] ( 836 ) 179 Analysis of and Prevention Countermeasures for Underground Engineering Risks in Red Bed Areas with Developed Karst ZHU Weibin1, 2 ZHANG Hua3 HUANG Hui4 The karst caves in the red bed are mainly developed around the basin, where the ground is dominated by coarse-grained tuffaceous or calcareous clastic rocks. The mixed ground condition formed by the said stratum and the overlying water-rich loose soil layer may pose a significant risk to the construction of underground works.Through the analysis of a series of engineering accident cases and in combination with the characteristics of construction methods of underground engineering, such as pile foundations, foundation pits and bored tunnels, this paper systematically summarizes main underground engineering construction risks in the red bed with developed karst:water inrush and mud gushing, slurry leakage and mud pumping, as well as resultant ground surface collapse and structural damage etc., and establishes the risk models regarding various construction methods. On this basis, prevention countermeasures are put forward, such as comprehensive geological survey, pretreatment with grouting and filling, observational construction and design, as well as hydraulic balance device for emergency use. 2021 Vol. 58 (5): 179-186 [Abstract] ( 511 ) [HTML 1KB] [ PDF 7015KB] ( 953 ) 187 Discussion and Application of New Grouting Technology in Hourglass-shaped Karst in Wuhan Metro Project LI Shenkui Tao Lan WU Shengxian Statistics, summary and analysis are carried out in terms of karst ground collapse cases in Wuhan, karst treatment schemes and measures in various regions, with the aim of showing the importance of karst grouting.Hongjian Road Station and running tunnel sections at its both ends of Wuhan Metro Line 6 cross the hourglassshaped karst geological structure in the first terrace of the Yangtze River, where such karst treatment measures as curtain grouting in rocks as well as grouting and filling in karst caves are adopted. However, a series of problems are encountered during the construction, e.g. sand particles leak due to drilling and grouting, steel casing could not be pulled out, grouts penetrate into the sand layer, grouting pressure could not be maintained so that karst caves could not be filled effectively, grouts could not be measured effectively, and so on. In order to solve these problems, the traditional karst grouting hole forming process, flow monitoring process, grout ratio and final grouting completion stan? dard are optimized through consultation, demonstration and with reference to water conservancy construction experience and preliminary experimental study. A set of karst grouting technologies, e.g. "steel casing + inner PP-R pipe+ hole forming in rocks with drill rod + grout stop plug + grouting flow recorder", are studied and explored. In karst grouting, different grout ratios are selected in different periods, and the final grouting completion standard suitable for geological characteristics of the project is explored as well. The karst treatment practice at Hongjian Road Station and the running tunnel sections at its both ends verified the applicability and effectiveness of the new grouting technology. 2021 Vol. 58 (5): 187-195 [Abstract] ( 540 ) [HTML 1KB] [ PDF 3695KB] ( 1043 ) 196 Experimental Study on Dust Reduction Technology for D&B Tunnelling WANG Fei1 WANG Qing2 JIAO Weining2 Qin Wei3 In order to quickly deal with the dust and harmful gas after tunnel blasting, based on the Jiaoding tunnel project, this paper conducts a field test to get the distribution of the initial concentrations of dust and CO at seven characteristic points at different positions away from the tunnel face; and then it studies the variation pattern of dust and CO concentration in the tunnel under longitudinal ventilation conditions; furthermore it proposes the technical solutions of dust reduction and removal with water bag and mobile spray respectively and verifies the superiority of the two solutions through field tests. The study shows that: (1) the average concentration values of dust and CO at 50m away from the tunnel face after blasting are 8.2 times and 26.05 times of the allowable concentration, respectively;(2) under the condition of longitudinal ventilation, the first 10 mins is the stage where the dust and CO concentrations fall the most rapidly, with the rate of reduction reaching 50%; (3) the dust reduction effect of the water bag is significant, and the maximum reduction of dust and CO concentration can reach 52.62% and 43.91% respectively; (4)the dust removal effect of the mobile spray is better than that of the water bag, and the first 20 mins is the stage of the most rapid reduction of dust and CO concentration, and the reduction rate can reach 60%. 2021 Vol. 58 (5): 196-203 [Abstract] ( 530 ) [HTML 1KB] [ PDF 4386KB] ( 1079 ) 204 On Ground Reinforcement Measures and Influence on Surrounding Building and Utility Deformation during Enlarging Construction of a Shield Tunnel by CRD Method FENG Jinghui ZHU Ying Engineering practice shows that the influence of urban underground structure construction on surrounding environment is one of the main risk sources in engineering construction. In view of this, for the junction section between the link line of Zhengzhou Metro Line 1 and Line 2 and the main line of Line 2 the numerical simulation and field monitoring are carried out to study the relevant control measures and the influence of enlarging construction of a shield tunnel by CRD method on the surrounding environment. The results show that: (1) compared with the other three control measures, using the control measure of advanced small grouting pipe + large pipe roof + radial grouting bolt, the ground settlement, existing pipeline deformation and existing building deformation can meet the specified control requirements, with the best control effect and controllable environmental risks; (2) Enlarging excavation has the greatest influence on ground settlement, accounting for 54.47%~59.39% of the total settlement. The settlement caused by enlarging excavation in the upper left part accounts for 18.31%~18.52% of the total deformation, so the monitoring should be strengthened at this stage. 2021 Vol. 58 (5): 204-212 [Abstract] ( 520 ) [HTML 1KB] [ PDF 6703KB] ( 1018 ) 213 Research on Pedigree-based Design and Query Recommendation System of Cutters of Full-Face Tunnel Boring Machines HUANG Hongying GUAN Huisheng ZHAO Kang LIU Cheng With the increase in the application of full-face tunnel boring machine (TBM) technology, TBM cutters have been developing rapidly, not only in large quantity but also in various types and forms, which meet the excavation needs in various strata, but also make the management, query, selection and design of cutters very complex and difficult. Therefore, it is imperative to establish a query recommendation system for the TBM cutters as well as a pedigree design idea of the cutters. On the basis of the analysis on information about cutter types, characteristics and applications, this paper establishes a pedigree of cutters of full-face TBMs in three dimensions: market demand, product characteristics and evolutionary lineage. Then, it puts forward the coding rules and designs the coding structure of the cutters of full-face TBMs according to the characteristic pedigree of cutters. Based on Microsoft Visual Studio, this paper builds a Windows application of query and recommendation system for TBM cutters, including query modules of cutters and project cases, as well as recommendation module of full-face TBM cutters based on an expert system. The research results could not only help manufacturers to design the cutters according to the feature classifi? cation and development process, but also help engineers reasonably select and configure cutters by using the query recommendation system. 2021 Vol. 58 (5): 213-220 [Abstract] ( 463 ) [HTML 1KB] [ PDF 4930KB] ( 852 ) 221 Research, Development and Application of an Intelligent Grooving Robot System for Defect Remediation in Existing Railway Tunnels SHI Yun1 YANG Lingwu2 HU Minghua1 LEI Gang1 TANG Hao2 In order to solve the problems of high labor intensity, low construction efficiency and low degree of auto? mation in terms of manual grooving operation during water seepage treatment in existing railway tunnels, this paper develops an intelligent grooving robot system based on the design concept of informationization and intelligence and in combination with the construction process of tunnel defect remediation. The system uses railway flat cars as the mobile carrier and has the functions of tunnel section scanning, model reconstruction, automatic planning of robot motion trajectory, flexibly cutting groove with shape under constant force control, real-time monitoring of system status and automatic dust removal and temperature reduction, etc. It can adapt to the wet and leaky environment in tunnels and has been successfully verified through application in the second subsection of the JLDH-1 lot of JiaozuoLiuzhou Railway electrication renovation project. The results show that the system can realize the informationization and intelligence of grooving operation in railway tunnels, improve the construction efficiency and reduce the labor intensity of workers. 2021 Vol. 58 (5): 221-226 [Abstract] ( 442 ) [HTML 1KB] [ PDF 2722KB] ( 700 ) 227 Statistical Analysis on Temporal and Spatial Characteristics of the Axial Force of Anchor Bolts in Tunnelling LI Pengfei1 HUANG Jingluo1,2 CHEN Keyi1 TONG Lei2 Based on the statistical data of axial forces of 282 anchor bolts in 68 monitoring sections of 33 tunnels, this paper investigates the overall distribution characteristics of the axial force of anchor bolts and the influence law of surrounding rock grades on it, discusses the time-history variation characteristics and spatial distribution law of the axial force of anchor bolts, studies the relationship between the axial force and the length of anchor bolts, as well as analyzes the influence law of tunnel excavation radius on the position of maximum axial force of anchor bolts,thus revealing the relationship between the neutral point of anchor bolts and the tunnel excavation radius. The results show that: the longer the anchor bolt length and the higher the surrounding rock grade, the longer it takes to reach the maximum axial force value of anchor bolts, and the time-history curve of the axial force is divided into three stages: the rapid increase stage, slow fluctuation stage and stabilization stage; from the perspective of spatial distribution law, the distribution of the axial force of anchor bolts is relatively discrete, but the maximum value often appears at the tunnel spandrel and haunch; the proportion of occurrence of the larger axial force increases with the increase of anchor bolt length; and the neutral point position of anchor bolts increases linearly with the increase of tunnel excavation radius. 2021 Vol. 58 (5): 227-236 [Abstract] ( 539 ) [HTML 1KB] [ PDF 3734KB] ( 736 ) 237 Numerical Simulation and Experimental Study of Mechanical Properties of GINA Waterstop WANG Weiqiang LUO Yonghuan KONG Lingjun ZHANG Yinxi CHEN Yanbei Through analysis and comparison of the finite element modeling methods for GINA waterstop in im? mersed tube tunnels, it establishes 2D and 3D finite element models for the waterstop, analyzes vertical compression displacement and contact pressure of the waterstop, maximum principal strain of the rubber and vertical reaction force of loading tools, as well as finally compares the numerical simulation and test results of the waterstop. The results show that there are great differences between 2D and 3D finite element models of GINA waterstop in terms of analysis results. As for the 3D model of the waterstop, the numerical simulation results of the vertical reaction force of the loading tools are basically consistent with the test results, which verifies that the analysis results of the waterstop 3D model are rational; the numerical simulation results of the 3D finite element model are independent of the longitudinal length and circumferential perimeter of the waterstop. And so the scaled model can be used to perform numerical simulation and experimental study of GINA waterstop, with the priority of the segmented GINA waterstop for finite element modeling, as its more time-saving, efficiency and accuracy. 2021 Vol. 58 (5): 237-243 [Abstract] ( 659 ) [HTML 1KB] [ PDF 2856KB] ( 826 ) 244 Effect of Functional Admixtures on the Performances of Mortars Filling behind Tunnel Vault Secondary Lining PENG Lei1,2 HE Wenmin1,2 HUI Haitao3 LI Bingliang1,2 GAO Ni2 As for the vault voids and other issues of tunnel secondary lining, based on the basic performance re? quirements for filling mortars of secondary lining of railway tunnels, and under mixture formula of OPC∶SAC = 0.65∶0.35, cement∶sand = 0.55∶0.45, water: aggregate = 0.18 and 10% fly ash admixture, this paper studies the effect of functional admixtures on the performance of mortars in terms of the fluidity, bleeding rate, strength, expansibility and dry shrinkage, etc. The results show that: under the mixing dosages of 0.3% tartaric acid, 0.2% lithium carbonate, 0.06% plastic expander, 0.15% defoamer and 0.12% water-retaining thickener, the filling mortar can be prepared with properties of self-compacting, no bleeding, no segregation, high early and long-term strength, and micro expansion; through the bonding test of filling mortar and lining concrete, field radar nondestructive testing and vault core drilling, the results show that there is a good bonding capability between the filling mortars and the tunnel secondary lining, which could mitigate voids behind tunnel secondary lining and avoid the separation between filling materials and secondary lining concrete. 2021 Vol. 58 (5): 244-251 [Abstract] ( 465 ) [HTML 1KB] [ PDF 2631KB] ( 1016 )

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