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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2020 Vol.57 Issue.6 Published 2020-12-25 1 Study on the Evacuation and Rescue Technology for Super-long Railway Tunnels with Super-deep Shafts in Disaster Scenarios FAN Lei YANG Changyu Train fire and fault accidents are harmful to operation safety in super-long railway tunnels, which brings great challenges to personnel evacuation, external rescue and operation management. Based on the Gaoligong?shan tunnel (34.538 km long) on Dali—Ruili railway which is the current longest traffic tunnel in China, relevant researches on the evacuation and rescue scheme for disaster prevention of the super-long tunnel are carried out, the general principle of evacuation and rescue for disaster prevention and evacuation strategies under different disaster scenarios are determined, and the layout pattern of the emergency rescue station under the condition of super-deep main and auxiliary shafts is put forward. Furthermore, the ventilation and smoke exhaust system for personnel evacuation from the emergency rescue station with shafts is established, the semi-transverse ventilation and smoke exhaust schemes for double-track tunnel option and single-track tunnel option in initial operation stage are put forward, and the disaster prevention and rescue management mode as well as the evacuation and rescue plan under fire scenarios are determined. 2020 Vol. 57 (6): 1-7 [Abstract] ( 728 ) [HTML 1KB] [ PDF 3114KB] ( 1336 ) 8 Research on Risk Classification and Assessment Method for Tunnels Crossing under High-speed Railway Subgrade LIU Jianyou1 ZHAO Yong2 LV Gang1 LIU Shufen3 LIU Chunxiao1 As for a tunnel crossing under the high-speed railway subgrade, the safety risk depends mainly on the disturbance caused by tunnel construction and the load bearing range of high-speed railway subgrade. According to the distribution characteristics of the additional stress in the soil layer of the high speed railway subgrade, it divides the load bearing area of the high speed railway subgrade into the main load bearing area, the secondary load bearing zone and the non-load bearing zone. According to the disturbance characteristics of the surrounding rock caused by the tunnel construction, it divides the tunnel surroundings into the loose, disturbed and unperturbed areas. According to the location relationship between the load bearing zone of the high-speed railway subgrade and the disturbance zone of the tunnel, the risk classification of the under-crossing tunnel project is carried out. The influence range of the under passing tunnel on the high-speed railway and the influenced tunnel section due to the high-speed railway are determined. The method has been successfully applied to the risk assessment of the running tunnel from Majiapu East Road station to Yongding Menwai Street station on Beijing Metro Line 14, which passes under Beijing-Tianjin intercity railway. 2020 Vol. 57 (6): 8-16 [Abstract] ( 707 ) [HTML 1KB] [ PDF 3549KB] ( 1047 ) 17 Evaluation of Adjacent Building Damages Caused by Tunnel Excavation Considering Foundation Buried Depth CHANG Yinsheng1,2 LV Le1 WANG Jingjing1,3 WANG Xudong1 Displacement of overlying stratum induced by tunnelling will result in damage to adjacent buildings. In light of the fact that Peck formula can only describe ground settlement, and according to the random medium theory,the displacement field of overlying stratum induced by tunnelling is predicted by using diffusion?convection model.Combined with the criteria for classification of building damages caused by differential settlements and tension cracks, the evaluation of adjacent building damages caused by tunnel excavation considering foundation buried depth is realized. By way of practical engineering cases, the influence of foundation buried depth on building damage is discussed, and it shows the evaluation results considering foundation buried depth are consistent with the actual results, verifying the rationality of considering foundation buried depth in evaluation of adjacent building damage. 2020 Vol. 57 (6): 17-24 [Abstract] ( 674 ) [HTML 1KB] [ PDF 2259KB] ( 1218 ) 25 Review on BIM Technology Applied in Tunnel Engineering in China LIU Xinghong1 LIN Daming2 YU Jin3 QIU Renke4 SU Xingju4 LOU Chonghua5 WANG Hui6 ZHANG Zhongjian1 BIM technology is characterized by visualization, simulation and optimization, which can solve problems like design errors and disordered construction management. The application cases of BIM technology in domestic tunnelling are summarized, and the application statuses of BIM technology in the three stages of tunnel design, construction and operation and maintenance are expounded. In the design stage, BIM technology can assist related personnel to carry out applications like 3D visualization model establishment, works quantity statistics, collision check and stability analysis; in the construction stage, BIM technology can assist relevant personnel to carry out visual technical clarification, optimization of construction method and process plan as well as construction management; in the operation and maintenance stage, BIM technology can assist relevant personnel to manage tunnel equipment and tunnel maintenance digitally, which helps relevant personnel to respond to sudden safety incidents. 2020 Vol. 57 (6): 25-35 [Abstract] ( 657 ) [HTML 1KB] [ PDF 3348KB] ( 1311 ) 36 Intelligent Control Technology for the Shield Segment Prefabrication CAI Qingcheng According to the characteristics of the shield tunnel segment prefabrication process, the modern "Inter? net of Things" information technology is used to construct the segment IoT platform and develop a prefabrication management system for shield segments by means of radio frequency identification (RFID), QR code, sensor, scanner, intelligent integrated machine and other information sensing devices. It realizes the real-time acquisition and optimization analysis of the quality and production information data during the whole segment production process.Meanwhile, it combines the automatic production equipment with the IoT information platform of segments through the program-controlled instrument such as the industrial PLC, realizes the optimal control of segment production and the equipment through the big data analysis and optimization technology of the platform, making the production more intelligent and digital. The research and application of this technology will have a positive and far-reaching impact on the production management and quality control level of the segment prefabrication. 2020 Vol. 57 (6): 36-45 [Abstract] ( 657 ) [HTML 1KB] [ PDF 9860KB] ( 1141 ) 46 Numerical Simulation Analysis of the Rockburst Mechanism in the Tunnel with High Geostress WEI Yinghua LIU Fei In the excavation process of tunnels with high geostress, the original stress equilibrium state is destroyed causing the stress concentration phenomenon and occurrence of serious geologic hazards such as rockburst, wall caving and so on. Based on the Tingzhou tunnel on Ganzhou-Longyan railway in Fujian province, it uses 3D-Sigma software to establish a 3D three-dimensional tunnel excavation numerical model. Taking the stress data obtained by hydraulic fracturing as boundary conditions and estimating the input parameters of the rock mass on the basis of Hoek-Brown strength criterion, the distribution and variation of stress field in the process of tunnel excavation is explored. The results show that in the process of tunnel excavation, the maximum horizontal principal stress, shear stress will form stress concentration area at the top of the arch and arch shoulder, which will lead to brittle failure of rocks. Through simulation monitoring of 7 typical positions on the same cross section of the tunnel, it is found that the changes of the stress field at the top of the arch, the arch shoulder and the bottom of the tunnel are obviously sensitive to the excavation of the tunnel, the rockburst will be more easily occur at these positions. The predicted rockburst locations by the numerical simulation tally with the practical rockburst occurrence locations in the project case. Therefore, the numerical simulation results can be used to explain the regularity of the rockburst, providing some guiding values for the prevention of the engineering rockburst. 2020 Vol. 57 (6): 46-54 [Abstract] ( 619 ) [HTML 1KB] [ PDF 3774KB] ( 1326 ) 55 Upper Bound Analysis of Three-Dimensional Active Stability of a Shallow Tunnel Face Based on the Strength Reduction Method JIANG Wujun1 LI Dejian2, 3 QU Tuoyu3 Tunnel face is often prone to collapse accidents. In order to evaluate its active stability effectively, a three-dimensional (3D) multi-sliders failure mechanism of tunnel face is constructed. Then, the upper bound analysis of 3D active stability of a shallow tunnel face is carried out based on the strength reduction method. Combined with upper bound limit analysis method, the objective function of the safety factor is established, and optimal upper bound solution of the safety factor is obtained based on nonlinear optimization program. The effectiveness of this proposed method is proved by comparative analysis. Meanwhile, the effects of different parameters on the safety factor and failure modes are analyzed. Results show that the safety factor FS increases linearly with the increase of cohesion c and internal friction angle φ, but it decreases with the increase of ground surcharge σs and soil gravity density γ, and decreases nonlinearly with the increase of overload ratio C/D. The effects of overload ratio C/D and internal friction angle φ on the active failure modes are significant, while cohesion c, ground surcharge ss and soil gravity density γ are insignificant. When active failure zone of is not reaching to ground surface, overload ratio C/D and ground surcharge ss have no influence on the calculated results. 2020 Vol. 57 (6): 55-62 [Abstract] ( 577 ) [HTML 1KB] [ PDF 4047KB] ( 1006 ) 63 3D Numerical Simulation of the Interaction between Rock Mass and Shield TBM Passing through the Fault Fracture Zone XU Peng1 HUANG Jun1 ZHOU Jianbo1 TANG Jinzhou2 TBM jamming may occur due to exceeded convergence of surrounding rock when a shield TBM passes through the fault fracture zone. Taking a water conveyance tunnel as the engineering background, the numerical simulation is conducted by FLAC3D to explore the changes of frictional resistance of TBM passing through the fault fracture zone and to analyze the influence of advance support strength and overcut gap on force applied on shield TBM and jamming risk. The simulation results show that the frictional resistance of TBM is the main control factor to cause the jamming of TBM passing through the fault fracture zone, the radial relative convergence of surrounding rock at the TBM shield is 0.16 m which exceeds reserved deformation value, the squeezing force and forward frictional resistance on shield are high with the maximum frictional resistance of 108.71 MN, and the maximum peripheral convergence declines by around 17.06% after supporting with anchor bolts, which means the anchor bolt support can significantly influence the peripheral deformation of surrounding rock in fault fracture zone. 2020 Vol. 57 (6): 63-69 [Abstract] ( 736 ) [HTML 1KB] [ PDF 2255KB] ( 1309 ) 70 Research on Optimization of Tunnel Cyclic Advance Rate Based on Ubiquitous Joint Model ZHANG Quan1 JIANG Annan1 WU Hongtao2 DUAN Longmei2 In order to determine the reasonable cycle advance rate of the highway tunnel in rock with developed joints, the distribution laws of peripheral displacements, stresses and plastic zones are simulated and analyzed under the advance rates of 0.5 m, 1.0 m, 1.5 m and 2.0 m based on ubiquitous joint model by taking the No. 2 Zhenfengling tunnel in Jilin Province as the background. The research results show that the peripheral displacement,stress and plastic zone are positively correlated with the advance rate and the uprush occurs when under the advance rate of 2.0 m; based on a comparison and analysis of the numerical simulation results under the four working conditions, it is considered that the cyclic advance rate of the tunnel in jointed rock mass should be 1.5 m under action of shotcreting and anchoring; the numerical simulation results of the tunnel in jointed rock mass based on ubiquitous joint model agree well with the on-site monitoring results, verifying the rationality of the 1.5 m advance rate. 2020 Vol. 57 (6): 70-77 [Abstract] ( 655 ) [HTML 1KB] [ PDF 4129KB] ( 1181 ) 78 Research on the Reinforcement Optimization of the Shield Tunnel End in Water-rich Pebble Stratum YANG Tao As for the Nanning rail transit line 3 project in water-rich pebble stratum, sand gushing and water in? rush accidents are prone to occur when shield launching or arriving. In this context, the paper analyzes the stability of the end soils under different buried depths, transverse reinforcement thicknesses, vertical reinforcement thicknesses and longitudinal reinforcement lengths through theoretical calculations and numerical simulations. On this basis, the thickness of water-stop reinforcement is optimized, an economical and safe reinforcement range of the shield tunnel end is determined. Combined with local construction experience and characteristics, the end reinforcement scheme including concrete diaphragm wall + sleeve valve tube grouting + well point dewatering is proposed for the studied project. The actual engineering application effect shows that the proposed scheme is applicable to the water-rich pebble formation. 2020 Vol. 57 (6): 78-85 [Abstract] ( 642 ) [HTML 1KB] [ PDF 2389KB] ( 1128 ) 86 Calculation Method and Engineering Application of Drawdown Induced by Tunnel Water Leakage Large amounts of water leakage and water inflow in tunnel will cause the drop of water level of the sur? rounding strata and induce a large area of strata subsidence, threatening the safety of constructions (structures) and pipelines in the surrounding area. Considering the influence of atmospheric precipitation recharge, a calculation method for drawdown in surrounding strata induced by tunnel water leakage is established based on areal well theory, and practical application and analysis are conducted. The results show: (1) the drawdown curve of surrounding strata induced by tunnel water leakage is in a shape of symmetrical "subsidence trough", the closer to the tunnel center the more significant the drawdown; (2) the drawdown develops in a trend of log function with continuous water leakage; (3) for the studied project, water blocking measures should be taken in light of the drawdown more than 3 m in a scope of 50 m nearby after continuous water leakage of 30 d. 2020 Vol. 57 (6): 86-92 [Abstract] ( 556 ) [HTML 1KB] [ PDF 2204KB] ( 1330 ) 93 Analysis on the Reliability and Prediction of Residual Life of Lining Structure of the Heat Supply Tunnel ZHANG Jiawen1,2,3 LEI Weidong1 HE Shaohui3 Based on the field investigation on a heat supply tunnel in Beijing, a subset simulation method is adopted to calculate the safety reliability of the operating tunnel lining structure, and the failure probability and reliability index are obtained by improving the subset simulation method through optimizing the sample points of Hua-Wang point set. Compared with traditional Monte-Carlo method, it is found that the lower the failure probability, the more the precision and efficiency of improved subset simulation method. A new method for predicting the residual life of lining structures is established by the homogeneous Markov chains. In light of the carbonization law of concrete structure of heat supply tunnel, the concept and form of deterioration matrix are given, the ASI value of current state of lining structure is obtained, and Bayesian method is introduced to modify the prediction model by taking the current ASI as the boundary condition, with the results showing that the modified Markov chain model is applicable to predicting the residual life of lining structure of the operating heat supply tunnel. 2020 Vol. 57 (6): 93-100 [Abstract] ( 574 ) [HTML 1KB] [ PDF 2349KB] ( 819 ) 101 Study on the Deformation and Mechanical Behaviors of the Tunnel Lining Structure Induced by High Temperature in the Fire Scenario WU Zhaofeng1 HU Huirong2 The high temperature in a tunnel fire will cause serious damage to the lining structure and affect the me? chanical behaviors of the lining structure, finally reducing the safety of the lining structure. In view of this, it analyzes the deformation and stress distribution in the tunnel lining structure under high temperature in course of a fire using the Ansys FEM software, which is of great significance to the fire resistance design of the tunnel lining structure. 2020 Vol. 57 (6): 101-106 [Abstract] ( 635 ) [HTML 1KB] [ PDF 3152KB] ( 1204 ) 107 Analysis of Dynamic Response of Track Structure Affected by Different Degrees of Separation of the Monolithic Track Bed in Subway Tunnels ZHU Lei1 YANG Yan2 RAO Hui1 NIU Pengbo2 The monolithic track bed structure of subway tunnels generally suffers from the separation defect, threat? ing the safe running of the train. In order to analyze the influence of different degrees of separation defects on the dynamic characteristics of the track structure, a finite element simulation model of rail-track bed-tunnel is established in this paper. Based on the investigation results of the separation defects of the monolithic track bed in a subway, the track bed structure with different degrees of separation defects is set up, and the dynamic responses of the rail and track bed under different working conditions are calculated. The conclusions are as follows: 1) Track bed separation defects have occurred in the early stage of subway operation. The separation defects mainly distribute near the expansion joints, and on both ends of the track bed; 2) When the degree of separation is small, the width of the separation is far greater than the displacement amplitude of the track bed, and so the dynamic response of the track structure is hardly affected by changes of the separation width; 3) When the bottom surface of the track bed is not penetrated through by the separation, the vertical displacement increment of the rail and the track bed is limited.However the load-bearing capacity of the track bed will be significantly reduced when the separation is completely through the track bed. The vertical displacements of the rail and track bed have a positive correlation with the length of separation; 4) The track structure vibration will be intensified in varying degrees due to separation of the track bed, and the structural vibration is more sensitive to the change of separation depth. 2020 Vol. 57 (6): 107-114 [Abstract] ( 681 ) [HTML 1KB] [ PDF 5457KB] ( 927 ) 115 Finite Element Analysis and Parameter Optimization of the Cutterhead of Composite Shield Machines LUO Dan The mechanical performance of the cutterhead of composite shield machines is an important criteria to judge whether the structure design is reasonable. In this paper, the force property of the composite cutterhead is analyzed by finite element method, the contours of stress and deformation distribution are obtained. As for the main load bearing parts with insufficient safety margin, the high strength steel is used to instead, and finally the parameters are optimized through the DesignXplorer module of Workbench. The safety coefficient of the optimized cutterhead is 1.54, and the weight is reduced by 1.17 tons, so the safety and economy of the composite cutterhead are improved.The research results can provide reference for structure design and material selection of the shield cutterhead. 2020 Vol. 57 (6): 115-119 [Abstract] ( 682 ) [HTML 1KB] [ PDF 3021KB] ( 1022 ) 120 Design of the Shading Shed for Highway Tunnel Groups Based on the Visual Adaptation Curve BAO Yifan1,2 WANG Mingnian1,2 QIN Pengcheng1,2 CHEN Jinyu1,3 YAN Tao1 HAN Changling4 As for the sudden change of light and shade at the entrance and exit of highway tunnel group, the influ? ence of light and shade effect on drivers can be reduced by setting a dimming device at the entrance and exit of highway tunnel group. In this paper the definition of highway tunnel group is given from the perspective of disaster prevention and rescue, and driving vision; considering the operation characteristics of the highway tunnel group, the shading shed is selected as the light reducing facility, and two design modes, e.g. the connected and unconnected shading sheds are given according to the spacing between the tunnels; the light transmittance and length of shading shed at connection section of the tunnel group are designed with reference to the visual adaptation curve. The research results can provide reference for the awning design of similar highway tunnel groups. 2020 Vol. 57 (6): 120-126 [Abstract] ( 614 ) [HTML 1KB] [ PDF 1256KB] ( 1047 ) 127 Discussion on Visual Communication Based Art Lighting Design of Highway Tunnels LIU Chang1, 2 NAI Lei2 LIU Yanling3 HAN Rui1 Lighting of the highway tunnel is usually made up of three types, i.e. functional lighting system, guiding lighting system and art lighting system. No matter which kind of lighting system it is, it should enable light communication to make drivers keep visual pleasure under the precondition of safe driving. The interaction between highway tunnel illumination and driver vision is the basis of tunnel illumination art design. Through a study on tunnel lighting art design of the interior space of Huitougou tunnel on Hegang-Dalian highway, it discusses the design methods of visual communication art of highway landscape, explores the application approaches of visual communication theory in highway tunnel lighting. 2020 Vol. 57 (6): 127-132 [Abstract] ( 609 ) [HTML 1KB] [ PDF 4514KB] ( 953 ) 133 Analysis of Mechanical Properties and Influencing Factors of High-filled Cut-and-Cover Tunnel in Trench MA Li1 WANG Qicai1 LI Sheng1 LIU Yapeng2 NING Guixia1 HAN Guoqiang1 As for few studies on the stress state of the arched open cut tunnel under high backfilling, the mechani? cal characteristics of high-filled open cut tunnels with arched cross-section in the cutting trench is studied through laboratory tests, the earth pressure distributions around open cut tunnel and stress variations outside tunnel arch ring along with backfilling height are obtained. The results show that the earth pressure distribution at the arched section on the top of open cut tunnel is in the shape of being large in the middle and small on both sides. When the backfilling height is low (less than 1.2 times of the tunnel height), the equivalent vertical uniform load is greater than the value specified in specifications, while being less than this value specified in specifications when the backfilling is high (equal to or greater than 1.2 times of the tunnel height). With the increase of backfilling height, the distribution pattern of earth pressure on both sides of open cut tunnel changes from "positive trapezoid" to "rectangular", and the earth pressure on bottom of open cut tunnel is uniformly distributed. With the increase of backfilling height, the external stress of the section at the spandrel varies little, but increases obviously at the vault, side wall and the bottom of the open cut tunnel. Subsequent numerical simulation analysis shows that the average relative error of earth pressure around open cut tunnel is 11.3%, and the average relative error of external stress is 14.5%, verifying the correctness of experimental data and the rationality of the numerical simulation parameters. Finally, the effects on the internal force of lining structure induced by sensitivity of the influential factors are discussed, such as the backfilling height, slope angle, backfill properties and the trench-width ratio. The results show that the slope angle and trench-width ratio have the most significant effect on the internal force of lining structure. To improve the me? chanical properties of the open cut tunnel in the practical engineering, the slope angle should be increased, and the trench-width ratio should be reduced as much as possible. 2020 Vol. 57 (6): 133-141 [Abstract] ( 628 ) [HTML 1KB] [ PDF 4139KB] ( 831 ) 142 Research on the Key Performances of Asphalt Protection Layer for the Concrete Pavement of the Immersed Tunnel ZHAO Guoyun1 WU Weihua2 LI Shuliang3 In order to meet the special requirements for asphalt protection layer of immersed tunnel concrete pave? ment, three kinds of asphalt protection layer of AC-10+asphalt roll, GA-10+epoxy resin with sand and AC-10+ stress absorbing layer are designed, and laboratory tests on the bonding performance between layers, performances of reflective cracking resistance, waterproofing and water damage resistance are conducted based on demonstration and analysis. The results show that the pull strengths between layers under normal temperature of the former two design schemes reach 2.15 MPa and 2.20 MPa respectively, being much higher than that of the third design scheme;the shear strengths between layers under normal temperature of the three design schemes reach 0.565 MPa, 0.145 MPa and 0.745 MPa respectively; the fatigue lives of the three design schemes are 4 587 times, 5 649 times and 2856 times given by reflective cracking resistance performance test using Overlay tester system; water permeability coefficients of the three design schemes are all relatively small and the water permeability coefficient of the second scheme is close to 0 mL/min; water damage resistance performance of GA-10 is better than that of AC-10. It is concluded that the design scheme of GA-10+epoxy resin with sand has the best performance and can be considered as the preferred scheme of asphalt protection layer for the immersed tunnel. 2020 Vol. 57 (6): 142-148 [Abstract] ( 606 ) [HTML 1KB] [ PDF 4077KB] ( 703 ) 149 Analysis and Treatment of Blind Pipe Blockage in Humaling Tunnel on Lanzhou-Chongqing Railway LEI Lin1 HUA Yongli1 LI Guanpeng2 QI Jun2 LI Dewu2 The local sections of the Humaling tunnel on Lanzhou-Chongqing Railway are characterized by rich wa? ter, highly alkaline groundwater, and the fast crystallization rate, which causes the serious drainage blind pipe to be blocked. With respect to the current situation of clogging diseases, referring to the investigation data of the drainage blind pipe blockage diseases during the tunnel operation, the chemical composition of the crystals is determined, the formation and development mechanism of the crystals is analyzed combining with the hydrological conditions, the clogging disease characteristics of the blind pipe are summarized, as well as the repair and treatment measures for tunnel drainage blind pipe blockage are proposed, providing the theoretical guidance and reference experience for treatment of crystallization blockage diseases in similar tunnel engineering. 2020 Vol. 57 (6): 149-153 [Abstract] ( 758 ) [HTML 1KB] [ PDF 1673KB] ( 1387 ) 154 Study on Characteristics and Sources of Crystal Components of Leakage Water in the Loess Tunnel WU Yuzhe1 LI Guanpeng2 JIA Qiqi1 QI Hongyun1 LI Dewu2 Aiming at the crystallization disease of leakage water occurred in the Shangzhuang tunnel in Lanzhou ar? ea, a statistical analysis on the characteristics of the leakage water crystal is conducted, the chemical components of leakage water and crystal are measured, and the source of crystal components is discriminated by means of analytic hierarchy process (AHP). The calculation results show that: the main components of the leakage water crystals of the loess tunnel are Ca2+ and Mg2+ ions in limestone, dolomite and brucite; CO32- mainly comes from the dissolved CO2 in groundwater. 2020 Vol. 57 (6): 154-159 [Abstract] ( 536 ) [HTML 1KB] [ PDF 2081KB] ( 1100 ) 160 On Scavenging Performances of Cleaning Solvents for the Clogging in the Drainage System of Karst Tunnels HONG Yingwei1,2 QIAN Xiaqing3 LI Junhui3 YANG Henwei4 ZHANG Peng3 In order to solve the blocking problem of the drainage system in karst tunnels caused by karst crystalliza? tion, the scanning electron microscopy and chemical analysis experiments are carried out to obtain the microstructure and chemical compositions of the karst crystals acquired in the drainage pipes of the karst tunnel. Then chemical compositions of solutions for scavenging the Karst crystals are studied, the experiments on the solution concentration and dissolution effect are performed to determine the optimal concentration of the cleaning solution on the basis of analyzing the relationship between the solution concentration and dissolution rate. The results indicates that the solution of the unimolecule carboxylic organic acids reagent or the polycarboxylic organic acids reagent with an optimal concentration of 2 000 ppm and a dichromate index of 17.71% can effectively remove the karst crystals in the drainage system under the premise of ensuring green and environmental protection. 2020 Vol. 57 (6): 160-170 [Abstract] ( 520 ) [HTML 1KB] [ PDF 3737KB] ( 790 ) 171 Comprehensive Geological Prediction of Dongtianshan Tunnel Entrance Passing through the Fault and Intensely Weathered Water-rich Zone XUE Jun1 ZHANG Chengrui1 YE Zijian2 YE Ying3 The engineering geology and hydrogeological conditions of the entrance section of Dongtianshan tunnel are extremely complicated. The tunnel passes through the silty clay cover layer, the holocene active seismic fault F1 and the highly weathered water-rich tuff sandstone successively. Due to water-sealing of the silty clay cover layer,local water resistance at the F1 fault and water supply from the melted permafrost snow of Mount Tianshan, the highly weathered tuff sandstone has formed a wide range of water storage structure, leading to great risks and challenges in the construction of left and right entrance sections of the tunnel. In this paper, a comprehensive geological prediction method combining geological record-geophysical exploration-drilling is adopted, the spatial relationship and genesis of the fault and confined weathered fissure water are clarified, as well as the water inflow during tunnel excavation is predicted combined with field water inflow survey and a series of technical means, which ensures safe and smooth construction of the tunnel. 2020 Vol. 57 (6): 171-176 [Abstract] ( 435 ) [HTML 1KB] [ PDF 4650KB] ( 925 ) 177 Study on Construction Technology of Mined Metro Tunnel in Large-thickness Saturated Soft Loess Stratum CAO Ping LI Jiwei LU Zhiqiang LIU Jianwei The tunnel project in saturated soft loess is characterized by unfavorable engineering behavior and high construction risk. Taking the mined tunnel of Xi′an metro line 5 as the background, the main construction technical measures and effects of the mined tunnel under large-thickness saturated soft loess stratum are studied based on the site construction process, monitoring data and several groups of finite element numerical simulation. The research result shows that: unwatering is easy to realize in the saturated soft loess and its engineering behaviors are good after dewatering, so dewatering is an important means to treat saturated soft loess; the settlement caused by dewatering in saturated soft loess layer is large while the settlement in the area beyond the dewatering affected area is mainly integral and uniform, and the differential subsidence is small; dewatering or a combination of dewatering and grouting should be given the priority as for the tunnel closely adjacent to the important building. Isolation pile can be adopted to effectively protect the adjacent building when it′ s necessary; the grouting effect in saturated soft loess stratum is poor in condition of no dewatering, so more specific and appropriate grouting technology and grouts need to be studied. 2020 Vol. 57 (6): 177-185 [Abstract] ( 562 ) [HTML 1KB] [ PDF 3440KB] ( 958 ) 186 Study on the Construction Technology for EPB Shield Crossing under Dense Buildings in Upper-soft and Lower-hard Stratum with Shallow-buried Depth LIU Hui1 LI Yanqing2 When the earth pressure balance shield passes under the crowded buildings in upper-soft and lowerhard stratum with shallow-buried depth, it is easy to cause building damages. Taking the Changsha-ZhuzhouXiangtan intercity railway project as an example, in which a ?9.34 m earth pressure balance shield passes under the Nanhu hardware market, it puts forward the construction technology for the shield passing under dense buildings in unfavorable geological conditions, and describes the building foundation reinforcement technology, control technology of shield driving, soil conditioning technology as well as adaptive modification of the shield equipment, building assessment identification, etc. The application results show that, through implementing the combined construction methods, the deformation of the building group is effectively controlled, and no adverse social influences such as housing cracking, tilting and collapse are caused, thus ensuring the smooth construction of shield tunnelling. 2020 Vol. 57 (6): 186-192 [Abstract] ( 608 ) [HTML 1KB] [ PDF 3636KB] ( 1091 ) 193 Mined Construction Technology of Tunnel Group at the Junction of Metro Main line and Connection Line in Karst Stratum TIAN Ruizhong As for the running tunnel section from Central hospital station to Huaita Donglu station on Xuzhou metro line 2, the karst located in the section is relatively developed with poor regularity and rich water. And the construction is subjected to risk because of the large span of cross passage and simultaneous construction of tunnel group.Given this, a numerical model of tunnel group at the junction of main line and connection line is established by using ABAQUS software and considering four kinds of construction sequences. The optimal construction sequence scheme for running tunnel is obtained by analyzing the stress distribution of the soil mass and primary support of cross passage, as well as the overall construction scheme and specific construction measures for the tunnel group are proposed. The application practice results show that ground surface settlement can be effectively controlled by proposed mined construction scheme for tunnel group at the junction of metro main line and connection line in karst stratum,guaranteeing the safety of surrounding buildings and underground pipe lines. 2020 Vol. 57 (6): 193-199 [Abstract] ( 607 ) [HTML 1KB] [ PDF 4053KB] ( 767 ) 200 Research on Roof-ripping Construction Technology for Tunnels under Fractured Surrounding Rock Conditions LIU Yi1,2 HE Zuhao1,3 WANG ZhiMin1 MA Chao1,2 LIU Wen1,3 The transition from small section tunnel to large section tunnel is one of the difficulties in tunnel con? struction. Based on the Xinlian running tunnel section of Shenzhen metro lot 2131, this paper studies the construction scheme optimization for transformation from G5 small-section tunnel to C5 large-section tunnel, uses three-dimensional finite element method to calculate and analyze the advantages and disadvantages of various construction methods, and compares the calculation results with monitoring data. The results show that using the construction method of longitudinal climbing and roof-ripping, it can better control the deformation of surrounding rock and ground settlement after tunnel construction, avoid the initial support deformation and cracking caused by the longitudinal extrusion of fractured surrounding rocks as far as possible and reduce the construction risk. 2020 Vol. 57 (6): 200-206 [Abstract] ( 663 ) [HTML 1KB] [ PDF 4490KB] ( 1093 ) 207 Treatment Measures for Collapses of the Shallow-buried Highway Tunnel with Large Cross-section and Its Effects Analysis YANG Lin1,2 JIANG Hong1,3 CHEN Peishuai1,4 YUAN Qin1,3 Proper treatment measures for tunnel collapse can ensure the safety of tunnel construction and effective? ly avoid the secondary collapse. Based on the background of the collapse and cave-in event at the entrance of the tunnel of Shenzhen outer ring expressway, this paper analyzes the causes of the collapse, proposes the corresponding measures to deal with the collapse, and analyzes the treatment effect of the collapse by numerical simulation and monitoring measurement. The results show that the factors like upper-hard and lower-soft stratum, poor construction quality of pipe-roof and excessive blasting cycle are the main reasons to cause the collapse and cave-in of the tunnel; it can safely pass through the collapsed area with the combination of sandbag backfilling, radial grouting of small conduit, normal grouting at working face and concrete supporting at the arch bottom. 2020 Vol. 57 (6): 207-213 [Abstract] ( 462 ) [HTML 1KB] [ PDF 2905KB] ( 941 ) 214 Application of T76S Self-drilling and Grouting Spiral Pipe-roof in Tunnel Collapse Treatment and Evaluation on Support Effect XIAO Donghui1 MENG Yafeng1 KONG Dekun2 ZHANG Heng1 WANG Qian1 Aiming at the fact that treatment of tunnel collapse usually delays the construction period seriously and increases the construction cost, the construction technology of T76S self-drilling and grouting spiral pipe-roof is introduced in tunnel collapse treatment and an evaluation is conducted regarding the construction process, key technical points and support effect based on the collapse treatment of certain tunnel on Shantou-Zhanjiang expressway.The application effects show that the force borne by initial support is reasonable, the structure is safe and the support effect is good after treatment of the tunnel collapse. 2020 Vol. 57 (6): 214-218 [Abstract] ( 535 ) [HTML 1KB] [ PDF 1927KB] ( 1099 ) 219 Countermeasures and Construction Optimization against the Water Inrush Event in a Water-rich Tunnel Section GUO Qingjun Based on the construction of Guanyinyan tunnel of Hunan-Guangxi railway capacity expansion project, which passes through the water-rich ground, this paper first introduces the advanced geological prediction methods applied to the railway tunnel construction in the water-rich section. In view of the water inrush and mud inrush event encountered in the process of tunnel excavation, the comprehensive technical means such as shotcrete incorporated with steel mesh and anchor bolt, concrete blocking wall, mortar anchor bolt, curtain grouting and advanced pipe roof are adopted for disaster treatment. According to the advanced geological prediction results, the waterproof and drainage measures and construction scheme for the tunnel crossing the water-rich ground are optimized to ensure the safety of tunnel construction and operation. 2020 Vol. 57 (6): 219-223 [Abstract] ( 504 ) [HTML 1KB] [ PDF 588KB] ( 1123 )

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