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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2020 Vol.57 Issue.4 Published 2020-08-25 1 The Key Way is to Release the Genuine Rock Pressure—Discussion on Problems of Tunnelling in Squeezing Ground WANG Jianyu Squeezing of weak rock is essentially associated with creep caused by exceeding a limiting shear stress. In case of high in-situ stress, large deformation of surrounding rock may occur. During the deformation, a so called“genuine rock pressure”builds up and acts on the support structures according to“convergence-confinement”model. The load jointly borne by support and rock mass is different from the“discrete pressure”due to weight of discrete body and it might be called“genuine pressure”. Restrained by the understanding of discrete pressure load, it is difficult to find the reasonable means to deal with squeezing deformation. Several issues of the tunnel in squeezing rock mass are discussed in terms of the characteristics of genuine pressure, and it points out that the feasible solution in heavily squeezing ground is to release the genuine rock pressure by application of a yielding support system in combination with a certain amount of over-excavation, whereas the amount of over-excavation may be reduced by use of untensioned rock bolts. 2020 Vol. 57 (4): 1-11 [Abstract] ( 625 ) [HTML 1KB] [ PDF 3703KB] ( 1173 ) 12 Design and Practice of Auxiliary Construction Scheme for Micangshan Tunnel Using Ventilation Shaft TANG Xie1 LIN Guojin1, 2 HE Jia1 WANG Jun1 In order to discuss the design rationality of the overall construction scheme for the super-long highway tunnel with auxiliary adit, and accurately control the construction period and cost, the principles of construction with the help of auxiliary adit are discussed, the auxiliary construction efficiency and construction cost per linear meter by using shaft are calculated, the designed water inflow volume for shaft in case of adverse grade construction is estimated, and it comes the following conclusions: (1) it is necessary to use auxiliary adit to assist the construction of tunnels with distance of blind heading more than 5,000 meters or tunnel length larger than 10,000 meters, and the ventilation shaft should be given a priority as an auxiliary adit if it is set for operation ventilation; (2) the auxiliary construction by vertical shaft (inclined shaft with rail) is expensive and its lifting capacity is limited, the trackless in? clined shaft, parallel adit or cross passage should be chosen preferably regarding the auxiliary construction of tunnels and the slope should be controlled within 12.3%; (3) on the basis of predicted water inflow volume and the assumption of homogeneous aquifer, the calculation method of designed water inflow volume during construction and the rational allocation of drainage facilities are given. 2020 Vol. 57 (4): 12-19 [Abstract] ( 625 ) [HTML 1KB] [ PDF 2284KB] ( 1283 ) 20 Application of Peripheral Strain and Squeezing Factor Methods in the Prediction of Large Deformation of Tunnel Surrounding Rocks LIAO Yankai1 GUO Deping1 LIU Zhiqiang2 CHEN Dayang2 Squeezing deformation is an urgent problem to be solved in the construction of soft rock tunnel in the ar? ea with high ground stress, and deformation prediction is the key to controlling tunnel deformation under high ground stress. On the basis of previous research results, the grade and magnitude of large squeezing deformation of certain soft rock tunnel are predicted by squeezing factor method and peripheral strain method respectively, pertinence control measures are proposed, the predicted results agree with the measured values, providing a reference for the construction of similar projects. 2020 Vol. 57 (4): 20-26 [Abstract] ( 673 ) [HTML 1KB] [ PDF 2548KB] ( 1064 ) 27 Study and Evaluation on the Design Adaptability of Shield Cutterhead System SUN Jianping TANG Zhaoping The shield construction effects in different strata are greatly different because of complex geological conditions. The customized shield machine and design scheme for a specific project can not perfectly fit into other projects, and so the problems of evaluation of design adaptability of shield cutterhhead system need to be solved urgently. In this paper, the influence mechanism of design adaptability of shield cutterhead system is analyzed, and an analysis model and an evaluation method for design adaptability of shield cutterhead system are proposed based on improved TOPSIS method by taking the quality membership matching degree between current design and target design as the initial data of the evaluation model. Based on the current design of a cutterhead system, its design adaptability is analyzed and evaluated for its application to metro construction in certain city. It is concluded that the adaptability of the 17 design items of the shield cutterhead system is general, and the adaptability sequences of the 9 evaluation indexes in descending order are adaptability of engineering construction, adaptability of tunnelling parameters, technical adaptability, adaptability of excavation face stability, adaptability of environmental protection, adaptability of construction safety, adaptability of economy, adaptability of geological conditions and adaptability of durability. The proposed model and method can effectively evaluate the design adaptability of cutterhead system, provide scientific basis for decision making of rebuild and maintenance when the shield machine is reused in other projects, and improve the design adaptability and market competitiveness of cutterhead system. 2020 Vol. 57 (4): 27-36 [Abstract] ( 632 ) [HTML 1KB] [ PDF 2542KB] ( 1198 ) 37 Design and Application of Advanced Geological Prediction System of TBM for Gaoligongshan Tunnel YANG Tianren HE Fei NING Xiangke ZHANG Xiao TIAN Yanchao Aiming at the Gaoligongshan tunnel with large buried depth and complex geology, in order to accurately understand the geological conditions in front of the working face during the TBM construction, a set of advanced geological prediction system, which can be mounted on TBM equipment is designed by taking the characteristics of TBM equipment into consideration. The system consists of a three-dimensional induced polarization instrument and a three-dimensional seismograph. By innovatively designing of built-in telescopic electrode on the cutterhead and shield, using the rotary joint of integrated brush to transmit the electrode signal of the cutterhead, and using rotary hammer, it solves the problems of poor adaptability, long forecast period, influence on construction efficiency and difficult loading of the traditional D&B method geological forecasting system on TBM. The application result indicates the system is easy to operate, it is fast and accurately to acquire signal, and the prediction results are accurate and reliable. 2020 Vol. 57 (4): 37-42 [Abstract] ( 738 ) [HTML 1KB] [ PDF 3101KB] ( 1154 ) 43 Development and Application of Multi-point Independent Loading Testing System for Tunnel Lining LIU Yuyang1 LAI Hongpeng2 WANG Minxing3 HE Qiumei4 Tunnel lining model test is an indispensable method to study the mechanical and cracking behaviors and guide the design optimization as well as maintenance and reinforcement of tunnel lining structure. This paper introduces a multi-point independent tunnel loading testing system which can apply load on the fifteen key positions of a large size lining model at a low speed and high precision based on the load distribution pattern and magnitude of secondary lining, realizing physical simulation of load induced deformation and cracking behaviors of lining structure under complex loading conditions. Taking a lining section with shallow overburden of certain loess tunnel as the background, a model test of load induced deformation of secondary lining with 1∶10 similarity ratio is conducted on the basis of site monitoring results of load applied on the secondary lining, and the cracking characteristic and the law of strains changes of secondary lining are summarized. The results show the loading effect of this system is good and the loading accuracy meets the requirements of engineering test, and the test result is helpful to predict the cracking development and determine the key area of lining reinforcement. 2020 Vol. 57 (4): 43-51 [Abstract] ( 678 ) [HTML 1KB] [ PDF 3841KB] ( 1135 ) 52 Study on Reliability of Steel Fiber Reinforced Concrete Segments of Metro in Marine Strata ZHENG Aiyuan1 XU Bin2 CHEN Xiangsheng1 The selection of segment materials determines the segment performance and the overall safety and reli? ability of the structure. Steel fiber reinforced concrete materials have better mechanical properties than that of normal concrete in terms of crack resistance, earthquake resistance, fatigue resistance and impact resistance. Therefore,based on the reliability theory, steel fiber is added into the concrete material to optimize the mix design, and a series of tests are carried out to study the reliability of steel fiber reinforced concrete segment aiming at the segment lining of the Shenzhen shield tunnel in marine strata. The results show that: (1) in the case without large deformation, the best scheme is to use steel fiber reinforced concrete segments with less reinforcement; (2) under the same reinforcement ratio, the steel fiber concrete segment with less reinforcement has higher reliability than that of the original steel reinforced concrete segment, and it is affected by amounts of steel fiber admixture, varieties, shapes and aspect ratios; (3) steel fiber reinforced concrete segment can greatly improve the reliability of lining structure and meet the safety standard of metro tunnel structure durability in marine strata. 2020 Vol. 57 (4): 52-58 [Abstract] ( 640 ) [HTML 1KB] [ PDF 1170KB] ( 1179 ) 59 Study on Design Parameters of Sealing Gasket for Segment Joints of Shield Tunnel CHEN Yunyao1,2 ZHANG Junwei1 MA Shiwei2 LI Xue1 In order to study the design parameters of shield tunnel sealing gasket, firstly it analyzed the design sta? tus of sealing gasket material, section form and hole arrangement through statistical data. Based on the statistical samples, a linear regression analysis of outer contour parameters of gasket is conducted by taking the base length of gasket as a control variable. Secondly, the influence of geometric parameters on the waterproofing design of sealing gasket is analyzed by numerical simulation from the aspects of the number of rows of closing holes, pattern of closing holes and the changes of opening rates in different parts. Finally, referring to the range of rubber hardness recommended by relative national standards, the influence of rubber hardness parameters on waterproof design of the sealing gasket is analyzed. The results show that: the waterproof effect is the best with double-row pattern of closing holes of sealing gasket for shield tunnel segment joint; the waterproof effect is good with pair-hole pattern of closing holes; both the fully enclosing compression force and average contact pressure between gaskets have negative corre? lation with aperture ratio; if the Shore hardness of rubber is within the scope of 60-70, both the average contact pressure between gaskets and the average contact pressure between gasket and concrete have linear positive correlation with rubber hardness. 2020 Vol. 57 (4): 59-66 [Abstract] ( 573 ) [HTML 1KB] [ PDF 2947KB] ( 1136 ) 67 Study on the Influence of Flexibility Ratio on Tunnel Seismic Dynamic Response REN Lei1 NIU Bin2 GUO Ting2 LIU Songyu2 The strength of dynamic interaction between tunnel lining and surrounding rock under earthquake ac? tion is closely related to the relative stiffness between them. In order to analyze the influence of relative stiffness between tunnel lining and surrounding rock on structural internal force under earthquake action, the concept of flexibility ratio is introduced in aseismic numerical analysis. Through the treatment of seismic waves and boundary conditions, the variations of structural internal forces under different surrounding rock grades, different lining thicknesses, different concrete strength grades and different tunnel diameters are calculated and analyzed, and the basic law of seismic response of tunnel lining under different flexibility ratios is presented. The results show that: the larger the flexibility ratio, the smaller the structural internal force; in the case of multiple tunnel defenses, the stiffness of adjacent structures should change gradually and the thickness of each layer should not be too large. 2020 Vol. 57 (4): 67-73 [Abstract] ( 601 ) [HTML 1KB] [ PDF 2867KB] ( 1192 ) 74 Numerical Simulation Study on the Deformation and Failure Mechanism of Tunnel Surrounding Rock under the Effect of Water-rich Sand Layer LIU Ping1 LIU Chi2 WANG Hongtao1 ZHANG Hongjun3 YANG Yong4 ZHANG Xin1 LIU Luyao1 In order to study the deformation and failure mechanism of tunnel surrounding rock under the effect of water-rich sand layer, taking a running tunnel of metro line M2 in certain city as the background, the effect of five factors of thickness of the sand layer, thickness of the water-resisting layer, underground water level and cohesion and frictional angle of water-resisting layer is considered. Twenty five comparison schemes are designed, a systematic numerical simulation and comparison are carried out, the influence law of different factors on the deformation and failure mechanism of surrounding rock and the sensitivity degree of each factor are obtained, and the corresponding engineering measures are given as well. The results show that the crown is the key part of surrounding rock deformation and failure in tunnels subjected to the effect of water-rich sand layer; the deformation and area of plastic zone of surrounding rock at crown decreases with the increase of the thicknesses of water-resisting layer, cohesion and internal friction angle, while the deformation and area of plastic zone of surrounding rock at crown keeps increasing with the increase of thickness of the sand layer or underground water level; the thickness of the water-resisting layer and cohesion are the significant factors that affect the deformation and failure of surrounding rock under such conditions, adequate safety thickness of water-resisting layer at crown should be guaranteed as for the design of tunnel alignment and grouting reinforcement of water-resisting layer can be taken to improve the stability of tunnel surrounding rock. 2020 Vol. 57 (4): 74-81 [Abstract] ( 603 ) [HTML 1KB] [ PDF 7224KB] ( 821 ) 82 Prediction Method for Surface Settlement in Tunnel Construction with Pipe Curtain Support JIANG Yongtao1 WANG Mingnian1 ZHANG Yiteng1 YU Li1 JIANG Fan2 XIAO Zerong3 Pipe jacking construction for pipe curtain will disturb stratum and cause deformation and surface settle? ment. At present the surface settlement caused by group pipes is calculated by superposition of single pipe settlement without consideration of the interaction of group pipes of pipe curtain. Taking the pipe curtain at exit section of Wenlinshan tunnel for example, which is constructed by the technology of mucking with screw conveyor and jacking with casing, a calculation method for the surface settlement of single-pipe jacking construction considering ground loss and construction stress is established based on stochastic medium theory and Mindlin solution, and the modified function for the surface settlement of group pipe construction is introduced to set up a calculation method for the surface settlement of group pipe construction; the change and distribution laws of surface settlements caused by single-pipe jacking and group pipe construction are analyzed and verified by the proposed calculation method and FLAC3D numerical simulation respectively. The results show that: (1) during the jacking process of steel pipes, at first the surface heaves in front and then subsides in the rear; (2) the surface deformation caused by steel pipe jacking gradually attenuates from the center line of the tunnel to both sides, with the affected scope within 12 m of the two sides; (3) the surface heaving caused by the subsequent pipe jacking is smaller than that caused by the first steel pipe, and the surface settlement is larger than that caused by the first steel pipe. 2020 Vol. 57 (4): 82-90 [Abstract] ( 627 ) [HTML 1KB] [ PDF 3666KB] ( 1176 ) 91 Research on Vault Ultimate Displacement at Different Tunnel Construction Stages in Surrounding Rock of Grade Ⅴ ZHANG Yiteng1 SUN Xingliang2 JIANG Yongtao1 YU Li1 JIANG Fan3 CHEN Mingyue3 XIAO Zerong4 The existing ultimate displacement and its management reference are mainly determined after the clo? sure of supporting structure of the common railway tunnel section, without considering the tunnel construction stages.Taking the existing high-speed railway tunnel which locates in surrounding rock of grade Ⅴ and adopts three bench method for example, it simulates the vault displacements in different construction stages by FLAC3D software, obtains the ultimate vault displacements in different construction stages based on cusp catastrophe theory. The results show that the ultimate vault displacements are affected by excavation of upper bench, middle bench, lower bench and invert in decending order and there is almost no effect by lower bench and invert excavation in the case of threebench construction in the surrounding rock of grade Ⅴ; under the calculated buried depth of 50-300 m, the ultimate displacement at vault in the same construction stage has a linear relationship with the buried depth. The sensitivities of surrounding rock parameters to the ultimate displacements are analyzed by grey correlation, and the influence de? grees on the ultimate vault displacement are rock mass density ρ, elasticity modulus E, cohesive force c, poisson rate μ and internal friction angel φ in descending order. 2020 Vol. 57 (4): 91-97 [Abstract] ( 579 ) [HTML 1KB] [ PDF 1319KB] ( 1075 ) 98 Influence of Deep Foundation Pit Excavation on Adjacent Buildings and Optimization of Reinforcement Measures WEN Shuli Excavation of deep foundation pit has significant effect on adjacent buildings, threatening the safety of structures. Based on the case of a deep foundation pit excavation of certain metro station adjacent to an existing building in Kunming, the reinforcement scheme is optimized by numerical simulation, and the influence of reinforcement depth and position on the horizontal and vertical displacements of existing buildings is studied. The results show that the numerical simulation results are close to the measured data and numerical simulation can reflect the influence of deep excavation on the surrounding buildings; with the increase of reinforcement depth, the displacement of existing building gradually decreases and amount of displacement reduction decreases gradually once the reinforcement depth exceeds certain limit; with an increase of the distance of reinforcement position away from existing building, the displacement of existing building gradually increases, and gets small when the reinforcement position is closer to the foundation pit. 2020 Vol. 57 (4): 98-103 [Abstract] ( 647 ) [HTML 1KB] [ PDF 1725KB] ( 1150 ) 104 Study on Calculations and Influence Factors of Bending Stiffness of Segment Ring Joints of Shield Tunnels ZHANG Jing1, 2 In order to obtain a calculation method for bending stiffness of the shield tunnel segment ring joint in longitudinal beam-spring model, the analytic method is adopted to deduce calculation formulas for bending stiffness of segment ring joint under simple bending and stretch bending conditions based on Shiba model, and a quantitative analysis is conducted on the sensitivity and the influence way of each influencing factor. The results show that the influencing factors of bending stiffness of segment ring joint are mainly the segment ring width, section size, ring bolt parameters and axial tensile force and so on, and the sequence of influence on bending stiffness of ring joint are section size, ring bolt parameter and width of segment ring in descending order; the way of influence of axial tensile force on bending stiffness of ring joint is different than that of above mentioned factors, under action of the axial tensile force the bending stiffness of ring joint presents obvious non-linearity characteristics, the relationship of bend? ing stiffness of ring joint, longitudinal bending moment and longitudinal axial force is of“step-shape”curved surface in 3D space, and the values of stiffness are maintained between two specific levels of upper bench and lower bench; when the surface of ring joint is fully opened under the effect of stretch bending, the bending stiffness of ring joint is reduced by around 40% compared with that of partially opened. 2020 Vol. 57 (4): 104-112 [Abstract] ( 607 ) [HTML 1KB] [ PDF 3432KB] ( 1022 ) 113 Analysis of Influence of Flowing Water in Tunnel on Freezing Effect of Cross Passage WANG Chengjing ZHANG Yong ZHU Chengshan HAN Xiang Aiming at the effect of flowing water in tunnel on freezing effect of cross passage during freezing process, it analyzes the effect of flowing water in tunnel on the temperature of the junction between segment and soil mass and the temperature of soil mass through the data measurement and numerical simulation by taking the construction of certain cross passage of Guangzhou metro as an example. The results show that there is almost no change of the temperature of the junction between the upper segment and soil mass but the temperature of the junction between lower segment and soil mass rises obviously and the closer to the tunnel bottom the larger of the difference of average temperature under the condition of flowing water in tunnel; average temperature of the junction between segment and soil mass in the upper reaches is obviously larger than that of lower reaches under the same depth of flowing water; when the flow velocity turns larger, the average temperature of the junction between segment and soil mass rises and the effect of flow velocity on the average temperature in the lower reaches is obviously larger than that of the upper reaches; the flowing water has effect on the temperature of soil mass within 2 m depth at the back of segment in the course of freezing. 2020 Vol. 57 (4): 113-118 [Abstract] ( 506 ) [HTML 1KB] [ PDF 3204KB] ( 881 ) 119 Research on Soil Plug Pressure-bearing Characteristics of Screw Conveyor with Variable Pitch MI Shipeng In practical engineering, the ability to prevent blowout is low for the large diameter screw conveyor. Blowout occurs from time to time when shield machine passes through the section with high water and soil pressure.A model of pressure bearing characteristics of soil plug is established to analyze the bearing capacity of soil plug.Taking a large-diameter screw conveyor of a shield used in Chengdu Metro as a reference, a simulated analysis on muck transportation process of a screw conveyor with equal or variable pitch is conducted through changing pitch of screw blade by discrete element simulation method. The simulation results show that: the movement velocity of soil mass in the soil plug section decreases by about 15.1% compared with the axial velocity in the soil intake section,and the total velocity decreases by about 6.7%; good soil plug can be formed in soil plug section in condition of variable pitch, and a design of screw blade with variable pitch can be used as a new means of shield tunnelling to prevent blowout; the design of variable screw pitch increases the wear in soil plug section, increases the force applied on screw shaft, the starting torque and the peak torque by about 20-40 kN, 21.5% and 28.6% respectively, therefore, it is necessary to increase the strength of screw blade and output torque of the screw conveyor with variable screw pitch. 2020 Vol. 57 (4): 119-126 [Abstract] ( 554 ) [HTML 1KB] [ PDF 2589KB] ( 821 ) 127 On the Law of Roadbed Slope Vibration Caused by Tunnel Blasting FAN Xiangxi1, 4 CAO Baoshan2 SHAN Renliang3 ZHANG Youbo2 WEI Haibing4 SONG Yongwei3 LIU Jian3 In order to study the law of slope vibration caused by fine delay control blasting, equivalent charge and equivalent distance are introduced and a new formula of vibration velocity attenuation is established using dimensional analysis method by taking the fine delay control blasting at the entrance of Heiyu tunnel reconstruction and extension as the engineering background; based on the measured data of four times of test, fitting verification is conducted and a comparison with Sodev′s empirical formula is carried out. Wavelet packet analysis is adopted to study the distribution of vibration energy. The research shows that: the prediction error of traditional Sodev′s formula is as high as 27.39% regarding this project, and the measured vibration velocity is generally larger than the calculated one, which is not conducive to guiding construction, while the max. prediction error of the improved empirical formula is 18.41%, indicating that the improved formula has good applicability; the blasting vibration energy is mainly concentrated in the range of 0-109.375 Hz and it is mostly concentrated in the range of 0- 46.875 Hz, around 1% of vibration energy is larger than 109.375 Hz; As the distance increases, the vibration energy concentrates the area of low frequencies, and the high-frequency energy is gradually absorbed by the rock mass. 2020 Vol. 57 (4): 127-135 [Abstract] ( 472 ) [HTML 1KB] [ PDF 3975KB] ( 904 ) 136 Optimization and Application of Smooth Blasting Parameters for Underground Powerhouse ZHANG Chengjun In order to control the excavation contour of the underground powerhouse and reduce the damage to the retained rock mass, it′ s necessary to optimize the parameters of smooth blasting. The parameters of smooth blasting are obtained based on the theoretical calculation, and orthogonal experiments are conducted by taking borehole spacing, linear charge density and burden as the influencing factors of smooth blasting and taking half-hole ratio as the evaluation index. The optimal blasting parameters are obtained by visual analysis and variance analysis of orthogonal experiment. The field test results show that smooth excavation contour is realized and desired effect is obtained with the optimized blasting parameters. 2020 Vol. 57 (4): 136-140 [Abstract] ( 526 ) [HTML 1KB] [ PDF 887KB] ( 931 ) 141 Model Test Study on Influence of Excavation Methods on Stability of Surrounding Rocks of the Soft Rock Tunnel in High Geostress Field DAI Cong1,3 HE Chuan2,3 LIU Chuankun2,3 GUO Wenqi2,3 Different excavation methods often have different influences on the stabilities of the surrounding rocks. Based on the Lanjiayan highway tunnel project, a three-dimensional geomechanical model test is conducted, the influences of three-bench method, upper-bench and lower-bench method as well as upper-bench and lower-bench method with reserved core soil on the stabilities of soft rock tunnels in high in-situ stress field are studied. The research results show that: (1) the crown settlement and arch foot convergence experience three development stages, i.e.advance deformation, excavation deformation and convergence in sequence with the variation of excavation step under above mentioned three construction methods, with an ascending order of three-bench method, upper-bench and lower-bench method with reserved core soil method and upper-bench and lower-bench method in term of deformation magnitude; (2) the radial force between primary support and surrounding rock is pressure with similar distribution characteristics, the maximum and minimum surrounding rock pressures occur at the foot of sidewall and invert crown, with an ascending order of three-bench method, upper-bench and lower-bench method with reserved core soil and upper-bench and lower-bench method in term of pressure magnitude; (3) the three-bench method is the one that is most conducive to the stability of surrounding rock during the construction of soft rock tunnel in high geostress field and meeting the requirements of construction progress to a certain extent. 2020 Vol. 57 (4): 141-149 [Abstract] ( 555 ) [HTML 1KB] [ PDF 5159KB] ( 936 ) 150 Model Test Study on Deformation and Failure of Large-span Flat Tunnel Caused by Additional Load CAI Xin1 LIU Huixi1 CHEN Fubin1 WU Lianbo1 NIU Bingyan2 LIU Xuezeng2,3 SANG Yunlong2,3 Based on the large-span flat Maluanshan tunnel in Shenzhen, the failure process of tunnel structure un? der the action of additional load in the surrounding rocks of grade Ⅳ and Ⅴ is studied by model test and the change rules of surrounding rock pressure, lining deformation and internal force of tunnel lining are analysed. The research results show that: (1) the surrounding rock pressure at crown increases at first and decreases later, and reaches the maximum with small lining deformation when additional load reaches certain critical value; (2) with an increase of additional load, deformation of lining experiences elastic stage, plastic stage and failure stage, and the lining deformation is large in the surrounding rock of gradeV; (3) with an increase of additional load, internal force of tunnel lining increases and the distributions of bending moment and axial force present the forms of "butterfly" and " rhombus",with more nonuniformity of distribution. 2020 Vol. 57 (4): 150-157 [Abstract] ( 548 ) [HTML 1KB] [ PDF 4440KB] ( 983 ) 158 Experimental Study on Seepage Detection behind Tunnel Segment with Sonar Technology TAN Xiaofeng1 LIU Dongjun2 YANG Zhiyong3 HU Chengkai4 The detection of groundwater seepage has always been a challenge for the metro tunnel. Taking the Nan? zhuang-Lvdaohu shield running tunnel of Foshan metro line 2 as an example, field test is conducted to detect seepage behind segment by three-dimensional velocity vector sonar technology. Detections are taken at different points under various slurry chamber pressures, fitting and imaging and data analyzing on distribution pattern of seepage field behind segment are carried out, and the positions of seepage behind segment are determined; by comparing of ground surface settlements and settlement rates before and after grouting, the feasibility and reliability of sonar technology to detect seepage behind segment are verified. 2020 Vol. 57 (4): 158-162 [Abstract] ( 540 ) [HTML 1KB] [ PDF 1776KB] ( 955 ) 163 Study on Silane Impregnation Design of Shield Segment under Chemical Corrosive Environment YU Yong LI Tengfei MA Junqiu In order to solve the problems of durability and anti-corrosion of shield segment under chemical corro? sive environment, a study of systematic design is carried out based on the Xiangjiang tunnel in Hengyang city. In light of the structural corrosion mechanism and guaranteeing of safety and reliability of segment structure within the design service life under chemical corrosive environment, the corrosion resistance design of segment durability is determined in terms of structure, material mix ratio, anti-corrosive paint and so on, and trimethyl amyl triethoxy silane is selected as an anticorrosive coating after a comparison; field process test of silane impregnated coating is carried out from aspects of silane impregnation depth, water absorption and chloride absorption for different spraying technologies and spraying amounts of silane coatings, and it is concluded that the downward spraying process has obvious advantages over the upward and horizontal spraying process in terms of effect and cost, it is suggested the downward spraying process is used to spray the inner and outer arc surfaces and the optimum spray quantity is 400 g/m2, horizontal spraying can be adopted for the end and side face of the segment and the optimum spray quantity is 500 g/m2. 2020 Vol. 57 (4): 163-170 [Abstract] ( 460 ) [HTML 1KB] [ PDF 2841KB] ( 1334 ) 171 Experimental Study and Selection Design of Domestic GINA Gasket for the Immersed Tunnel HU Jianzhong1 WANG Yong2 XU Guoping2 XU Yu2 YU Guangzhong3 GONG Yi2 GINA gasket is the waterproof lifeline of immersed tunnels. Based on the Hanjiang immersed tunnel in Xiangyang as the background, a full scale physical model test is conducted to study the compression, water tightness and stress relaxation of the domestic GINA gasket under various unfavorable conditions, and selection and design are carried out according to the test data. The research shows that: (1) compressive stress of the domestic GINA gasket gradually decreases with time and tends to stable converge, the 100-year average stress relaxation attenuation rate of domestic GINA gasket is about 35%; (2) with the increase of compression force, compression of GINA water stop tends to reach the limit value of its height by 60%, the allowable joint deflection will reduce the compressive stress of GINA water stop by 4.4%-9.2%; (3) the watertightness required minimum compression curve of domestic water stop is basically agree with that of a foreign product, with the deviation is about 0-15%; the watertightness required minimum compression increases slightly as for the joint with deflection angles of 0.1 and 0.22 degrees; in the case of vertical offset of joint by 1 cm, 3 cm, 5 cm and horizontal offset by 5 cm, no water leakage occurs and water tightness is not affected; (4) design of water stop should consider the joint opening and compression caused by the temperature change, concrete shrinkage and creep, uneven settlement of foundation, earthquake and so on under the normal and ultimate states of load capacity, and also meet the requirements for the minimum water tightness and the maximum compression; (5) performance of the domestic GINA water stop can meet the needs of the project and it has certain safety margin. 2020 Vol. 57 (4): 171-177 [Abstract] ( 642 ) [HTML 1KB] [ PDF 2968KB] ( 854 ) 178 Study on Monitoring and Prevention Technique for Harmful Gas in No.1 Inclined Shaft of Hongdoushan Tunnel CHEN Zhongyong1 SU Peidong1 HUANG Lu1 CHEN Haodong1 DU Yuben2 High-pressure harmful gas burst occurs in the No. 1 inclined shaft of Hongdoushan tunnel during the construction, and the high-pressure gas is mainly consist of CO2, H2S with high concentration, small amount of CO and H2 and other harmful gases, resulting in major safety risks for tunnel construction. Based on the characteristics of the harmful gas and the tunnel construction conditions, it presents a monitoring scheme mainly composing of automatic monitoring system and manual real-time inspection. By sorting out and analyzing the monitoring data, the concentration, distribution and escape characteristics of harmful gases are summarized, and a prevention technique for high-pressure and high-concentration harmful gases in advance drilling and working face drilling is proposed in light of the characteristics of different harmful gases, which mainly includes blowout prevention in advance drilling,real-time monitoring of gas pressure in boreholes, real-time monitoring of composition and concentration of harmful gas and ventilation velocity monitoring. 2020 Vol. 57 (4): 178-184 [Abstract] ( 453 ) [HTML 1KB] [ PDF 2485KB] ( 1064 ) 185 Technical and Economic Analysis on the Safe and Rapid Construction Method for Soft Rock Tunnels HE Yingnan Based on the construction practice of a soft rock tunnel on Dalin railway, a modified three-bench sevenstep construction method which uses glass fiber anchor bolts to reinforce working face is proposed, an overall process of rapid construction of tunnels in soft rock is given, the key points of process management are defined, and the effects of management techniques for rapid construction on tunnel construction efficiency and economic benefit are analyzed. The research shows that safe and rapid construction of the soft rock tunnel can be realized by optimizing arrangement of blast holes and initiation sequence, overlapping of working procedures and parallel working of different benches; compared with the conventional construction technique, the construction time of two procedures of mucking and steel arch setting, construction time of anchoring and shotcreting and total cycle construction time can be saved by 53%, 17% and 28% respectively, thus the construction efficiency is significantly improved in condition of safe and rapid construction. Further the total cost saving in terms of labour, mechanical equipment and management is ￥16.358 million, greatly improving the economic benefit of tunnel construction in soft rock. 2020 Vol. 57 (4): 185-193 [Abstract] ( 444 ) [HTML 1KB] [ PDF 3795KB] ( 1100 ) 194 Key Techniques for Rapid Construction of Parallel Heading of Karst Tunnel in Chongqing Section of Zhengzhou-Wanzhou Railway XIANG Daoyin1 WANG Minghui1 ZHU Jianguo2 LIU Dalin2 ZHANG Qiao1 In order to understand the geological conditions in front of working face, to deal with the geological di? saster caused by mud burst and water flow, to further add additional working face to realize advance parallel heading and sectioned construction and to meet the goal of construction period, taking the Xiaoshanxia tunnel of ZhengzhouWanzhou high speed railway as an example, construction organization and management of rapid construction of parallel heading of karst tunnel are discussed mainly from the aspects of improving the entry conditions, adjusting the construction organization, overcoming the construction difficulties of adverse slope, optimizing the construction scheme and so on. 2020 Vol. 57 (4): 194-200 [Abstract] ( 553 ) [HTML 1KB] [ PDF 2838KB] ( 998 ) 201 Vertical Roof Ripping Construction Techniques for Excavation of Main Tunnel from Inclined Shaft: A Case Study of the Large-span Metro Tunnel in Soft Surrounding Rock LIU Yi1 ZHANG Yong1 PENG Zhen1 CHEN Jiawei2 LI Yuanhai Aiming at the difficulty of deformation control during construction of main tunnel from inclined shaft for a three-line large-span tunnel in soft surrounding rock, a construction method suitable for vertical roof ripping construction of urban metro tunnel from inclined shaft is proposed by taking the roof ripping construction of Xinlian running tunnel of Shenzhen rail transit as an example, and the construction scheme, procedures and key points are described. Furthermore numerical simulation is adopted to explore the rationality of this construction method. The research results show that: (1) it is an effective way to take roof ripping construction through small pilot tunnel to climb into main tunnel with reinforced support at the intersection; (2) reinforced support at intersection of inclined shaft and main tunnel can solve the construction difficulty caused by large dimension gap between them; (3) roof ripping construction through small pilot tunnel climbing to main tunnel provides precondition for the installation of primary support of main tunnel arch frame and it is favorable for the main tunnel construction which switches to double sidewall construction later; (4) there is a stress relaxation zone of surrounding rock at intersection crown, and the rock mass displacement can be well controlled with roof ripping construction under the help of reinforced support. 2020 Vol. 57 (4): 201-207 [Abstract] ( 517 ) [HTML 1KB] [ PDF 4833KB] ( 905 ) 208 Research and Application of“ Drainage and Grouting Combination Technology”for Tunnels in High-pressure Water-rich Surrounding Rock WANG Hongmei1 PAN Guangming1 LIU Chunguo2 ZHANG Hongshun2 In order to deal with the difficulty of grouting process control of the tunnel in the surrounding rock of fully-weathered granite under high pressure and abundant water, a technology of combination of drainage and grouting is proposed. Concentrated high-pressure and water-rich area of tunnel surrounding rock is explored and analyzed by a comprehensive exploration method, the area for drainage and energy release beyond curtain is identified,the method of determining locations of water drainage holes and safety control measures are studied, and the effect of numbers of water drainage holes and drainage capacity on curtain grouting is researched. Connectivity test is conducted to disclose the distribution characteristics of water conducting fractures within curtain area, and the types of grouts and mix ratios regarding safe and controllable grouting in different areas of water drainage and curtain grouting are determined based on the laboratory test. The practical application results show the flow path of underground water in the drainage and energy release area beyond the curtain is changed and the surrounding rock in the area of curtain grouting is improved and good effect is obtained attributed to safe water drainage and controllable grouting. 2020 Vol. 57 (4): 208-214 [Abstract] ( 432 ) [HTML 1KB] [ PDF 3998KB] ( 1147 ) 215 Preparation Method and Performance Test of Modified Energy-storage Luminescent Materials for Highway Tunnels FENG Shouzhong1,2 GAO Wei1 Adoption of new energy-storage luminescent material will significantly promote the improvement of en? ergy-efficient lighting, safe driving and air environment of highway tunnels. Two kinds of new luminescent materials are prepared by high temperature solid phase synthesis method and high temperature crosslinking catalytic synthesis method, and tests on lightness and brightness intensification and increase of visual range of small objects as well as release of negative oxygen ion of new energy-storage luminescent material are conducted. The test results show that the brightness intensity rates of the new energy-storage luminescent materials prepared by above mentioned methods are 33.43% and 4.28%, average increases of the visual range of small objects are 33.7 m and 5.9 m, and the release amounts of negative oxygen ions are 1 084.4 per cm3 and 137.4 per cm3 under the same conditions. It is found the high temperature solid phase synthesis method is more suitable for the preparation of new energy-storage luminescent material. 2020 Vol. 57 (4): 215-218 [Abstract] ( 547 ) [HTML 1KB] [ PDF 1154KB] ( 1189 ) 219 Structural Non-destructive Evaluation of Cleaning Solvent for Clogging Removing of Karst Tunnel Drainage System HONG Yingwei1, 2 Drainage system blocked by Karst crystal is often encountered in tunnelling in Karst area, threatening structure safety and long-term operation of tunnels. A unimolecule carboxylic organic acid agent with optimal concentration of 2 000 ppm and dichromate index of 17.71% is identified as a cleaning solvent based on a study of preparation and efficiency of cleaning solvent for removing of drainage clogging in karst tunnel, and a non-destructive evaluation of selected cleaning solvents on tunnel lining concrete and PVC plastic fiber materials of drainage system is conducted. Firstly, a test of organic acid solvent soaked concrete specimens is carried out to evaluate the strength damage of concrete due to erosion by solvent. Secondly, an experiment of soaking PVC drainage board and plastic blind ditch tube with organic acid reagent solution is carried out to evaluate the effect of solvent on quality loss and corrosion damage of tunnel drainage system from the macroscopic and microscopic perspectives. The results indicate that strength index of concrete material is reduced by about 7%-9% due to erosion of unimolecule carboxylic organic acid reagent, while it barely has any corrosion damage on the plastic material of drainage system. 2020 Vol. 57 (4): 219- [Abstract] ( 454 ) [HTML 1KB] [ PDF 4795KB] ( 768 )

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