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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2019 Vol.56 Issue.1 Published 2019-02-25 Article 1 Discussion on the Composite Shell Lining WANG Jianyu The composite shell lining (CSL) becomes more popular and a kind of main types of linings in conven? tional tunnelling in China. But there are some misunderstandings on how to design a composite lining structure and especially on how to control the engineering quality of CSL. The effectiveness of primary support was emphasized and some key points concerning the design of secondary lining were presented in this paper. As to the key point of CSL engineering quality control, it described that attention ought to be focused on a good fit of primary support, secondary lining and waterproofing membrane, and the flexibility index of waterproofing membrane was proposed based on the evenness of substrate surface, a contrastive analysis on the advantages and disadvantages was conducted regarding the spray-applied waterproofing membranes and hanging waterproofing sheets. 2019 Vol. 56 (1): 1-5 [Abstract] ( 1336 ) [HTML 1KB] [ PDF 1989KB] ( 3179 ) 6 Present Status and Prospects of Research on Flexible Joint Models of Immersed Tube Tunnels WEI Gang1 LU Shijie2 The flexible joint of an immersed tube tunnel, which has large flexibility, can adapt to the uneven settle? ment caused by soft riverbed and meet the aseismic requirements and so has been widely used in practical engineering.However, it is difficult to build a model since there are many parts for the flexible joint and the functions are complex, thus the results of static and dynamic analysis are not accurate. In this paper, the types of joints and basic structures of flexible joints of the immersed tube tunnel were introduced, relevant review and summarization of the present status of research on flexible joint models both at home and abroad were presented with respects to theoretical calculation models and numerical calculation models, the function mechanisms of various kinds of models for flexible joints were described and the rationality and disadvantages were analyzed, finally some suggestions were proposed regarding the research of flexible joint model. Specifically, the model test of joints may be taken to make the results to be more intuitive; the main joint parts were considered and reasonable initial conditions were input,the stiffness of flexible joints was described by numerical solution; the reliability of joint models was verified by contrastive analysis with various research methods or models. 2019 Vol. 56 (1): 6-13 [Abstract] ( 989 ) [HTML 1KB] [ PDF 2117KB] ( 2172 ) 14 Discussion on Classification Method and Criterion for the Deep-buried and Shallow-buried Rock Tunnels QIU Chenyu1,4 ZHENG Yingren1 ZHANG Yantao2 TAN Wanpeng3 ZHAO Sangyi1 The traditional classification for the deep-buried and shallow-buried tunnels is based on the Protodya? konov′s pressure arch theory and not reasonable enough due to its limitation of this theory. In view of this the finite element limit analysis method was applied to the classification for the deep-buried and shallow-buried tunnels, and three principles were put forward. For the rock tunnel with surrounding rock of Ⅳ and Ⅴ, the classification for the deep-buried and shallow-buried tunnels is based on the failure modes of tunnel, it is defined as the shallow-buried tunnel if the fracture plane cuts through ground surface while it is defined as the deep-buried one if the fracture plane doesn′t cut through ground surface, the height of pressure arch of the shallow-buried tunnel obtained by using FEM strength reduction method can be taken as the dividing line for the shallow-buried and deep-buried tunnels.For the rock tunnel with surrounding rock of higher grade, the deep-buried and shallow-buried tunnels are defined according to the stability safety factor of the unlined tunnel, it is defined as the deep-buried tunnel when the stability safety factor is more than or equals 1.5 while the failure mode should also be considered to define them when the stability safety factor is less than 1.5. In addition, the division of deep-buried and shallow-buried tunnels should still consider the effects of environment, construction, geological structure, unstable block, which will cause the surrounding rock collapse and form loose pressure. At last, it is suggested that for the deep-buried and shallow-buried tunnels it can be calculated by elastic-plastic numerical analysis method, but for the shallow-buried tunnel it should also be analyzed according to the load-structure model to ensure safety. 2019 Vol. 56 (1): 14-21 [Abstract] ( 905 ) [HTML 1KB] [ PDF 2286KB] ( 2229 ) 22 Study on Surrounding Rock Classification of the Underground Powerhouse of Lenggu Hydropower Station WEI Xingcan LIU Siding XIAO Huabo WANG Gang Classification of surrounding rock is the key issue in the design and construction of underground caverns in hydropower projects, and it′s significant to properly determine the grade of rock mass. By using HC classification,[BQ] classification, Q classification and RMR classification methods, it studied the grades of rock mass of underground caverns and a correlation analysis on scores of various classification systems was conducted by the regression method, with the results show that it is more beneficial to rational grading of surrounding rock by comprehensive using HC classification, [BQ] classification, Q classification and RMR classification for the large-span underground cavern;the results of HC classification agree well with that of RMR classification if the lumpiness and integrity of rock mass are governed by structural surface. 2019 Vol. 56 (1): 22-26 [Abstract] ( 800 ) [HTML 1KB] [ PDF 1202KB] ( 2314 ) 27 Study on Water Inflow and Burst in the Hydraulic Tunnel of Hydropower Projects in Southwest China WANG Zaimin1 CHEN Yulin1 XU Mo1 ZHANG Shishu2 YONG Ping1 Hydropower is the critical technology to relieve the energy crisis and environmental pollution. As an im? portant structure of the hydropower project, safe construction and operation of the hydraulic tunnel is one key factor.The geological conditions are very complex in southwest China, and water inflow often occurs when the hydraulic tunnel passes through adverse strata, endangering the lives and properties. Based on the existing papers and documents, the water inflow and burst issue of the hydraulic tunnels of hydropower projects in southwest China was analyzed in this paper. It comes to the following conclusions: (1) the main types of hydraulic tunnels include tunnel groups at the hub area and long distance tunnels beside rivers; (2) governed by the hydrogeological structure, water inflow and burst events often occur through rock fissures for the tunnel groups at the hub area, and for the long distance tunnels beside rivers, the water inflow and burst events occur through rock fissures, in complex fractured zone and in karst area; (3) the surrounding rocks of hydraulic tunnels suffered from water inflow and burst are often characterized by developed fractures and structures as well as extensive distribution of soluble rocks; (4) in view of the safety, economy and ecology of the hydraulic tunnel, it is necessary to analyze the features of groundwater, optimize the detection technology for fractures and karst system, establish mathematical and numerical models of quantification of water inflow and burst, organize an expert team of decision making, compile specific, integrated and scientific regulations, and propose treatment measures. 2019 Vol. 56 (1): 27-32 [Abstract] ( 859 ) [HTML 1KB] [ PDF 1897KB] ( 2359 ) 33 Analysis of Treatment Methods for the Foundation of the Immersed Tunnel FENG Haibao1,2,3 SU Changxi3 In order to provide reference information for the selection of foundation treatment methods of the im? mersed tunnel, the construction methods and effects of the immersed tunnel foundation at home and abroad were studied, the advantages and disadvantages of the pre-bedding and post-bedding methods were analyzed in terms of technology, economy, risk, construction period and other aspects based on the characteristics of foundation treatment. The principles of treatment methods for the foundation under different geological and working conditions were proposed in view of the construction environment and structure of immersed tube based on a thorough analysis of engineering cases at home and abroad, and the necessity of developing the dredging equipment was put forward. 2019 Vol. 56 (1): 33-38 [Abstract] ( 912 ) [HTML 1KB] [ PDF 1502KB] ( 2866 ) 39 D-P Yield Criterion Based Elastoplastic Solution for a Deep-buried and Pressured Circular Tunnel Considering Seepage Effect WANG Sui1 ZHONG Zuliang1, 2 LIU Xinrong1, 2 Groundwater is normally rich in the deep-buried mountain tunnels, and the major principal stress of sur? rounding rocks will change under the different conditions of construction and operation stages of the tunnels. In order to study the effect of groundwater seepage, based on D-P yield criterion and considering seepage effect, the elastoplastic solution for the deep-buried and pressured circular tunnel was derived under the condition of plane strain for cases of the major principal stress to be the radial stress and tangential stress. The study shows that the results of DP criterion model are mainly consistent with those of M-C criterion and more conservative; the radial stress and tangential stress are no longer symmetrical with ground stress with an increase of radial distance in the elastic zone considering the effect of seepage, moreover the larger of the seepage pressure the greater of the deviations; under the same condition, the radius of plastic zone increases with an increase of seepage pressure in the stage of low internal water pressure while the radius of plastic zone decreases with an increase of seepage pressure in the stage of high internal water pressure. 2019 Vol. 56 (1): 39-46 [Abstract] ( 830 ) [HTML 1KB] [ PDF 1897KB] ( 1978 ) 47 Coupled Thermo-mechanical Numerical Simulation of the Radioactive Waste Repository LIU Haitao1 ZHOU Hui2 HU Dawei2 GAO Yang2 Based on the thermo-mechanical coupling characteristics of rocks, the temperature field and stress field in 1 000 years after excavation and backfill were calculated by using finite element program ABAQUS, and the evolution laws of temperature field of the nuclear waste repository and stress field of surrounding rocks and buffer material were obtained. The results show that the maximum temperature at the center of nuclear waste reaches 116℃ in 6.3 years after dispose, then decreases gradually and finally goes into the slow decreasing period. The conductivity of buffer material has great influence on temperature field of surrounding rocks, the higher the conductivity is, the lower the maximum temperature at the center of nuclear waste is. After backfill of the disposal tunnel and pit, the tensile stress of surrounding rocks is very large which is very close to the tensile strength and there are risks of tensile fracture failure. The tensile and compressive stresses are both very high in buffer material, tensile fracture failure could occur at the intersection of the disposal tunnel and pit, and compressive fracture failure could occur at the floor of the disposal tunnel. 2019 Vol. 56 (1): 47-55 [Abstract] ( 873 ) [HTML 1KB] [ PDF 5856KB] ( 1939 ) 56 Analysis on Karst Development Laws of Tunnels Based on the Markov Random Field HE Gaofeng1 LUO Xianqi1 FAN Xunyi2 ZHANG Yong3 In southwest China, there is a large range of carbonatite areas. With the construction of city infrastruc? ture, especially rail transit, geological disasters related to karst emerge one after another, and it ′ s critical to understand the law of karst development. As for this issue the geological analysis and geophysical prospecting are the common methods to be adopted. In view of superposition issue of physical property parameters of rock mass in geophysical prospecting, inversive identification of lithofacies was conducted based on maximum posteriori probability under the framework of Bayesian and the Markov property of the strata. Taking the Nanning rail transit line 2 as an example, interpretation and verification of karstcave and grike were carried out on the basis of karst development conditions and documents of drilling holes. The results show that: influenced by horizontal circulation zone of groundwater and fracture structure, the spatial distribution of karst caves and grike goes horizontally; grike often occurs in the marl 10 meters away beyond the station floor, and attention should be paid during construction due to the large size and good connectivity of the karst caves. 2019 Vol. 56 (1): 56-64 [Abstract] ( 817 ) [HTML 1KB] [ PDF 3944KB] ( 2009 ) 65 Research on the Calculation Method for Surface Settlements of the Foundation Pit Based on Random Medium Theory HE Qiaomin1 HU Weiguo2 In view of the surface settlement caused by excavation and dewatering of deep foundation pit, the con? cept of ground loss in random medium theory was introduced, the calculation formula for the surface settlement caused by foundation pit excavation was deduced, and the formula for surface settlement caused by changes of unit weight and penetration was deduced and improved, the determination of key parameters of random medium theory applied in calculation of foundation pit excavation was discussed by taking the effect of frictional resistance at support structure-soil interface on settlement into consideration, and a contrastive analysis of the calculation results by the methods proposed in this paper and reference[10] and the measured settlements was conducted. The results show that the surface settlement near foundation pit calculated by the method proposed in this paper is closer to the measured ones, the surface settlement caused by excavation and dewatering of foundation pit can be predicted more accurately using the proposed method; compared with the traditional methods, the calculation accuracy of this method is much higher within the scope of 1.5 times excavation depth while the calculation accuracy would be further improved beyond the scope of 1.5 times excavation depth by considering the effect of specific water retention of soil mass and frictional resistance at the side of support structure; as for the open foundation pit with support structure and dewatering in the pit, good prediction of surface settlement can be achieved with the calculation method proposed in this paper. 2019 Vol. 56 (1): 65-71 [Abstract] ( 981 ) [HTML 1KB] [ PDF 2289KB] ( 1961 ) 72 Study on Interaction Mechanism between Collapsible Loess and the Subway Underground Structure WANG Lixin1,2 LIU Baojian3 BAI Yangyang1,2 In order to study the interaction mechanism between collapsible loess and underground structure of the metro, the working principle of foundation bearing capacity of metro underground engineering and the principle of earth pressure acting on underground structure in loess stratum were discussed through theoretical analysis based on the experience of underground engineering in loess area. The differences between underground structure as underground hollow structure and general industrial and civil foundation were presented. The variations of base pressure,lateral earth pressure and top earth pressure caused by collapsibility of loess in underground structure of metro were studied through case calculations. The results show that: (1) the working principle of metro underground structure is not applicable to the traditional and classical theory of bearing capacity of foundation soil which is laterally slipping and extruded, and the base pressure generated is less than the self-weight pressure of original base soil and the base is similar to the favorable compensatory foundation in foundation and foundation design; (2) shear strength of loess is a saturated fast shear index at the moment of loess collapsing due to saturated water soaking, the lateral pressure coefficient approaches 1.0 which should be taken into account in design; (3) In loess stratum, if collapsible deformation of soil occurs within the scope of tunnel main body, the vertical earth pressure on tunnel roof increases significantly compared with that without collapsible deformation, which should be considered in design. 2019 Vol. 56 (1): 72-78 [Abstract] ( 785 ) [HTML 1KB] [ PDF 2233KB] ( 2147 ) 79 Deformation Prediction and Parameter Sensitivity Analysis of Pipe Roof in Shallow Soft Rock Tunnels Considering WANG Daoyuan1，2，3 YUAN Jinxiu1 WANG Jiping1 WANG Kai4 XIA Yong4 WANG Haijiao4 WEN Ming4 In view of the complexities of existing calculation methods and theories for tunnel pipe roof, effects of calculation parameters on analysis results and difficulties to obtain accurate theoretical solution or simplified calculation formula, a theoretical calculation model for predicting deformation of pipe roof as pre-support was established based on Winkler elastic foundation beam theory and considering the disturbance characteristics of surrounding rock, incomplete load bearing behavior due to unclosed support, differences of strata reaction coefficients and uneven load distribution, and a theoretical solution was obtained by solving 24 order equations. The results show that:(1) The analytical solution agrees well with numerical simulation value and field data, and it can be used to predict deformation of pipe roof; (2) it is available to have the optimal parameters of diameter, advance rate and strata reaction coefficient of pipe roof, the circumferential spacing is directly proportional to pipe roof deformation, it meets the requirement only if the length of pipe roof at the far end is not less than two times of the bench height in front of working face; (3)The sequences of controlling effect of vault settlement by adjusting pipe parameters are advance rate, strata mechanical behavior improvement by grouting, circumferential spacing, diameter and length in the order from good to bad. 2019 Vol. 56 (1): 79-86 [Abstract] ( 862 ) [HTML 1KB] [ PDF 2730KB] ( 1847 ) 87 Research on the Drainage Effect of Parallel Headings for the Water-Rich Mountain Tunnel WANG Chunmei LI Da ZHENG Qiang The parallel heading is normally used as the transportation channel during construction and the evacua? tion or drainage passages during operation for long mountain tunnels in complex geological conditions, especially in rich groundwater condition . But there is little thorough study of the influence of parallel headings on groundwater distribution around the main tunnel. On the basis of existing parallel heading design, and considering several affecting factors, such as height of water head, grade of surrounding rock, horizontal spacing and vertical height difference between the main tunnel and the parallel heading, the effect of the parallel heading on the water pressure around the main tunnel was calculated and analyzed. The results show that the decreasing amplitude of water pressure is large for the tunnel with high initial waterhead after installing the parallel heading; under different grades of surrounding rock, the decreasing amplitude of the waterhead of the main tunnel increases with the decrease of permeability coeffi? cient of rock mass, the better the surrounding rock is, the better effect the drainage of the parallel heading is; the horizontal clearance between the parallel heading and the main tunnel should be determined by giving priority to consideration of construction organization and safety, and generally 20 m is recommended; vertical position changes have little effect on water pressure distribution and it′s unnecessary to have a large vertical height difference. 2019 Vol. 56 (1): 87-93 [Abstract] ( 813 ) [HTML 1KB] [ PDF 1919KB] ( 1997 ) 94 Analysis of the Stability of River-crossing Pipelines against Uplift Based on the Strength Reduction Method ZHU Qinghua1 HUANG Jianfeng2 HE Yong3 SHAO Yong3 Traditional finite element method has been successfully applied in the analysis of the capability against uplift of pipelines, but it didn’t give the safety factors of the anti-uplift stability relating to the buried depth of pipelines. An ABAQUS model of anti-uplift of pipelines was established by using strength reduction method to take a two-dimensional numerical simulation of the behaviors of river-crossing pipelines under the effect of buoyancy, to observe the development process of plastic zone of soils and to determine the safety factor of anti-uplift stability.The results show that the factors of anti-uplift capability increase linearly as the function of the buried depth and the slope is governed by the friction angle of soil mass; equivalent values of and used in gravity analysis method, which may be taken as the applicable conditions in practical application cases, are obtained by comparing with the traditional gravity analysis method. 2019 Vol. 56 (1): 94-98 [Abstract] ( 915 ) [HTML 1KB] [ PDF 1862KB] ( 1748 ) 99 Mechanical Evolution Law of Macroscopic Deformation and Failure of Surrounding Rocks in Deep Mining WANG Xinfeng1,2,3 LUO Wenbo1 WU Zhendong3 CHEN Ziyang3 LI Yuhao3 In order to study the macroscopic deformation-failure characteristics and time-space evolution rules of stress distribution of surrounding rocks in deep mining, mechanical evolution laws of roof crack field, overlying rock displacement field and surrounding rock stress field in deep mining were studied by using the methods of computer numerical simulation and laboratory similar model test. The results show that the surrounding rock has experienced gradual failure process of transient mutation, jump development, sequential unloading and continuous transmission,overlying rock fissure field has the time and space evolution characteristics of pressure relief induced instability,crack opening, crack development, through- penetration, shrinking fitting and closed stability. The migration of strata has a strong influence on“adjacent space effect”: the roof surrounding rock is closer to the coal seam, the influence of displacement measurement line is stronger, and the range of spatial effect is more concentrated, the stage controllability of the strata movement becomes weaker, otherwise when the distance between the roof layer and the coal seam is larger, the impact mechanism of adjacent space decreases, overburden subsidence is smaller, the stress transfer and load transfer mobility is inert. The stress distribution of surrounding rock in deep mining has interval evolutionary characteristics of the significant influence on the near field mechanical effect and the weakening of the far field force chain bearing system. The sudden increase in stress of surrounding rock in short time and superposition effect of high stress concentration caused by irregular mining are the mechanical causes of impact dynamic instability of mining field. 2019 Vol. 56 (1): 99-106 [Abstract] ( 748 ) [HTML 1KB] [ PDF 3100KB] ( 1821 ) 107 haking Table Test on Dynamic Damage Behaviors of a Circular Tunnel with Voids behind the Lining Subjected to Near-field Ground Motions WANG Jianning1 DOU Yuanming1 ZHAO Huajie1 WEI Ming2 TIAN Guizhou1 Considering the effect of near-field ground motion, a shaking table model test was conducted to the cir? cular tunnel with voids behind the lining. A comparative analysis was taken with aspects of acceleration response of foundation field domain, dynamic earth pressure of soil-structure contact surface, acceleration response of tunnel structure and dynamic strain rules. Meanwhile, the effect of near field ground motion on dynamic damage behaviors of the tunnel structure was studied based on a damage model. The results show that: 1) there is slight difference in the acceleration response at the different cross sections of the circular tunnel in the process of seismic wave loading,and tunnel structure affects the peak acceleration of subsoil at two sides while the changes of spectrum characteristics are not obvious; 2) when the intensity of input near-field ground motion is small, the average peak acceleration at the cross section with top voids is also small but the average dynamic strain response is large while the average peak acceleration at the cross section with dense top is large but the average dynamic strain response is small; 3) the damage is most serious at the scope of ±30° of the top of the cross section with voids behind the lining, which agrees with the seismic damage of existing circular tunnel. 2019 Vol. 56 (1): 107-113 [Abstract] ( 857 ) [HTML 1KB] [ PDF 2083KB] ( 1795 ) 114 Study on Quantitative Evaluation Criterion for Stability of Tunnel Surrounding Rocks in Upper-soft and Lower-hard Strata WU Bo1，2，3 WANG Mingtao3 HUANG Wei1，2，3 For 5 groups of strata composed of surrounding rocks of common grades, a detailed analysis and systematic study on the quantitative evaluation criterion for the stability of tunnel surrounding rocks in upper-soft and lowerhard strata was carried out by finite element numerical calculation. The double indexes of crown displacement abrupt variation criterion and the safety factor reflecting the nature of tunnel failure were determined to identify the stability of tunnel surrounding rock. The self-stability of surrounding rocks under various combinations of 5 groups of strata was studied by a large number of numerical experiments, a quantitative grouping of rock mass stability was defined by the self-stability curve, and a quantitative evaluation criterion for stability of surrounding rocks was established. The research results play a role of refinement and supplement to the research of classification theory of stability of surrounding rocks in civil engineering field. 2019 Vol. 56 (1): 114-123 [Abstract] ( 877 ) [HTML 1KB] [ PDF 3865KB] ( 1778 ) 124 Analysis of the Fractal Structure of the Rock Mass Deformation of Deep-buried Hard Rock Tunnels YU Yang HONG Peng ZHU Chen ZHAO Xiushao As for the rock mass deformation and geological hazards of deep-buried hard rock tunnels, based on the calculation method of the fractural theory, it studied the fractal features of rock mass deformations during the construction of deep-buried water conveyance tunnels of Jinping II hydropower station. The results show that it has the temporal fractal characteristics for the deformation of surrounding rocks during the construction of deep rock tunnels, and it exhibits good self-similarity structural features; under the same buried depth, the maximum fractal dimensions occur at the tunnel crown, then it decreases at spandrel, and the minimum fractal dimensions occur at the side wall; as for the tunnel with buried depth of 500-1 800 m, the larger the buried depth is, the larger the increase of deformation fractal dimensions and the occurrence frequency of surrounding rock hazards; as for the tunnel with buried depth more than 1 800 m, the deformation fractal dimensions and the occurrence frequency of surrounding rock hazard tend to be stable and the buried depth has a little effect on it. 2019 Vol. 56 (1): 124-129 [Abstract] ( 815 ) [HTML 1KB] [ PDF 1889KB] ( 2051 ) 130 Influence of Crack Location and Depth on Stability of Surrounding Rock Mass ZHOU Lei ZHU Zheming LIU Bang ZHAO Yanlin ZHOU Qin The balance state of natural geostress will be damaged and stress will be redistributed during tunnelling, which will cause cracking, developing and cutting through of fissure under the effect of tectonic stress field or selfweight stress field, then tunnel collapse and instability will happen. A contrastive analysis was conducted regarding the effects of crack location, length, depth etc. on the stability of surrounding rocks of a horseshoe-shaped tunnel by numerical simulation and laboratory model test. As for the numerical analysis, it analyzed the failure modes of surrounding rocks and calculated the stress intensity factor of crack tip. As for the model test, the effect of cracks on compressive strength of tunnel model was studied. The research shows that: (1) the results of numerical simulation mainly agree with that of the model test; (2) the maximum effect on tunnel stability is those cracks at the corner of tunnel or at tunnel roof with 45° inclination; (3) the longer of a crack in tunnel is, the lower the compressive strength of tunnel model is; (4) as crack length reaches a certain value, the effect of crack depth on tunnel stability increases linearly; (5) the stress redistribution and failure patterns of surrounding rock mass are much effected by tunnel cracks. 2019 Vol. 56 (1): 130-138 [Abstract] ( 861 ) [HTML 1KB] [ PDF 3577KB] ( 1834 ) 139 Analysis of Mechanical Behaviors of the Small-spacing Tunnel in Squeezing Rock Masses ZHANG Xiongwei1,2 SONG Ye2 LIU Zhiqiang2 LI Ning3 HE Lei4 For the small-spacing tunnel, tube group effect and stability of middle rock pillars are the main chal? lenges, especially in squeezing rocks, it will result in that cracks occur earlier in the first excavated tunnel tube and then cracks occur at the right tube while construction is taken on the left tube. Based on the Xinchengzi tunnel which is a typical case of large deformation at the bellmouth-shape exit section in squeezing rock mass, a construction method of stress release with advanced pilot tunnel was proposed, and the effect was verified by comparison of structure test results and numerical analysis. The results show that compared with the conventional three-bench method, the forces acting on lining structure significantly decrease by using advanced pilot tunnel method to release stress, so it is practical both in theory and practice for the small-spacing tunnels in squeezing rock mass to use advanced pilot tunnel to release stress. 2019 Vol. 56 (1): 139-143 [Abstract] ( 845 ) [HTML 1KB] [ PDF 2475KB] ( 1625 ) 144 Prediction of Gas Emission of Tunnel under the Influence of Natural Gas in Oil Reservoir and Coal Bed Methane TIAN Kunyun1 ZHENG Jiyu1 WANG Ximin2 In order to know the gas emission of Yangshan tunnel during construction so as to determine the its gas level, the maximum volumes of gas emission from coal seam and the natural gas from oil reservoir were predicted using different-source forecast method and drilling flow method, based on site testing of the basic parameters and analysis on occurrence law of gas in coal strata and natural gas in oil reservoir. Meanwhile, a mathematical model of gas emission prediction of this type tunnel was established. The research results show that the coal seam through which the tunnel passes is located at a nitrogen band of gas weathering zone without dangers of coal burst and gas burst,and the maximum volume of gas emission from the coal seam is 0.037 m3/min; the maximum volume of natural gas from oil reservoir is 0.234 m3/min. So the maximum total volume of two kinds of gas source emission is 0.271 m3/min,much less than 0.5 m3/min, which means the tunnel could be determined as the low gas tunnel. The mathematical gas emission prediction model will provide a new method and approach for gas emission prediction of similar tunnels. 2019 Vol. 56 (1): 144-149 [Abstract] ( 787 ) [HTML 1KB] [ PDF 1292KB] ( 1730 ) 150 Ventilation and Real-time Monitoring of the Harmful Gas Components during the Construction of Tianmu Mountain Tunnel PANG Wei1 FU Hailu2 GENG Wei1 LIU Wei1 ZENG Aibin3 GUAN Baohong4 Lots of harmful gas release during tunnel construction by D&B method, and the ventilation and health protection during the tunnelling process is of great significance. Taking the Tianmu Mountain tunnel on the Hangzhou-Huangshan high-speed railway as the background, real-time monitoring of air quality after blasting was conducted and concentration variations of harmful gas before and after ventilation were compared to analyze the timespatial distribution law of the components of harmful gas and evaluate the ventilation effect. The results show that the air quality meets the standards after ventilation for 15 min with a volume of 2 688 m3/min required by dilution of exhaust gas emitted by internal-combustion engines, and the harmful gases do not exceed the standards for all the working shifts, which proves good ventilation effect. The results provide significant guidance for the environmental air quality control and health protection during tunnelling. 2019 Vol. 56 (1): 150-158 [Abstract] ( 780 ) [HTML 1KB] [ PDF 4324KB] ( 1916 ) 159 Corrosion Resistance of the Metro Tunnel Segments after Repairing of Segment Cracks XU Shaoyun1,2 GAO Peiwei1 XIAO Zhongping2 ZHAO Xiangmin3 PENG Hailong3 CHEN Weifeng Cracks often occur during manufacturing, construction and operation of metro tunnel segments, and the durability of repaired segments has direct effect on tunnel safety. Simulating different subway tunnel segment crack patterns, using the chloride ion permeation test and sulfate attack test, it studied the erosion resistance of the tunnel segments after repairing various segment cracks with innovative repairing material NR, and a comparison with the commonly used epoxy resin repairing material EC was conducted, with the results show that the concrete resistance to chloride ion penetration increases significantly, the repairing effect of C60 segment is better than that of C50; the repairing effect of segment with polypropylene fiber is better than that of the segment without polypropylene fiber;the repairing effect of PFC50 and C60 segments is better compared with the repairing material EC; after using NR repairing material, the resistance to sulfate corrosion of segment decreases slightly, the decreasing amplitude of bending strength and compressive strength of the repaired C60 segment is smaller compared with that of C50 seg? ment, and the remediation effect of compressive strength is better than that of bending strength; the decreasing am? plitude of compressive strength and bending strength against sulfate corrosion of the segment with polypropylene fi? ber is smaller than the one without polypropylene fiber and the remediation effect of compressive strength is better than that of bending strength; compared with the EC repairing material, the remediation effect of compressive strength against sulfate corrosion of C50 and PFC50 concrete segments is better and the remediation effect of bend? ing strength against sulfate corrosion of three kinds of concrete segments is better. 2019 Vol. 56 (1): 159-163 [Abstract] ( 800 ) [HTML 1KB] [ PDF 1398KB] ( 1855 ) 164 Experimental Study on Electrostatic Precipitator for Air Cleaning System in Road Tunnels YANG Honghai1 GUO Hao1 CUI Xinghua2 DU Tianhua2 MIN Yun2 Electrostatic precipitator (ESP), which separates particules from air stream by means of electrostatic field to reach the goal of air cleaning, has been successfully applied in highway tunnels in Europe, Japan and other developed countries. However it is still in an exploratory stage in China, and there are few industry norms and design standards specified for road tunnels. In this paper a set of ESP system was designed and tested in an operating road tunnel, with the research results show that the concentrations of particulates were largely reduced and the air quality was significantly improved thanks to the ESP system. It contributes to getting the experience in developing,designing and operating of the ESP system, and the theoretical basis for the application in domestic highway tunnels and underground space. 2019 Vol. 56 (1): 164-168 [Abstract] ( 853 ) [HTML 1KB] [ PDF 1834KB] ( 1898 ) 169 The Primary Support Deformation Mechanism and Supporting Measures for the Tunnel across Anticline Core Zone GAO Meiben1 LI Tianbin1 ZHENG Jianguo2 WANG Baoming3 MENG Lubo1 REN Yang1 In order to provide reference and technical support for the design and construction of the tunnel across anticline core area, special test was conducted at the section of K8+559-K8+527 of the Zhougongshan tunnel. The testing results show that the contact pressure at crown is larger than that of haunch and side wall at the test sections;a contrastive analysis on the results of test sections and verification sections was carried out and it was found the contact pressure deceases somewhat, which means the scheme of“support after release”and increasing reserved deformation is effective and reasonable; tunnel deformation is governed by the geological condition, unreasonable construction method and combination of various adverse factors are the inducing factors; the process of deformation and failure can be generalized as excavation—unloading—differential resilient deformation—layer separation—bending failure of the top roof as simply supported beam. The research results provide calculation parameters for theoretical analysis and also basic data for the following study, accumulating the experience for the design and construction of super-long tunnel in complex stress condition. 2019 Vol. 56 (1): 169-175 [Abstract] ( 840 ) [HTML 1KB] [ PDF 2449KB] ( 1942 ) 176 Study on Construction Method of the Intersection of the Urban Underground Interchange Tunnel YAN Zihai1,2 ZHANG Lifeng1,2 LU Junfu3 ZOU Jinjie1,2 The construction difficulty of an urban underground interchange tunnel is focused on the intersection where two tunnel tubes are incorporated into one-tube tunnel, so the construction is of high risks and the requirements for construction method and technology are rigorous due to multiple conversion of tunnel system modes, such as the super-large section tunnel, the double-arch tunnel and the small-spacing tunnel. Based on construction practice of the underground intersection of Zizhi tunnel in Hangzhou, a construction method and procedure were proposed, namely constructing the large tube from the small tube, then transverse enlarging excavation and finally reverse excavation. The rationality of the proposed construction method was verified by using FEM numerical simulation and monitoring and measuring considering the characteristics of the project. The results show that the construction method of climbing excavation of the adit + transverse enlarging excavation + reverse construction can guarantee the construction safety of tunnel intersection, solve the difficulty excavating from a small tube to a large one; during the construction of the bifurcated tunnel, the tensile stress of surrounding rocks mainly concentrates on the vault,arch bottom and middle rock pillar while the compressive stress mainly concentrates on the middle rock pillar, the haunch of the large arch tunnel and the haunch outside of the small-spacing tunnel; the maximum tensile stress ofthe lining structure occurs at arch bottom and the maximum compressive stress occurs at haunch. 2019 Vol. 56 (1): 176-184 [Abstract] ( 1029 ) [HTML 1KB] [ PDF 5635KB] ( 2009 ) 185 Drill-blast Excavation and Vibration Control of the Large-section Metro Station in Urban Areas ZHANG Weibiao Drill and blast construction of the metro station in urban areas has large effect and even damage on sur? rounding buildings and personnel. Taking the drill and blast excavation of the Honghu East Road station of Chongqing rail transit loop line as an example, the blasting scheme and design parameters were described in detail, main technical measures of partial excavation, three-stage wedge-shaped cut, pre-splitting blasting and hole-by-hole initiating network were taken in order to reduce effects of ground settlement and blasting vibration on surroundings to the maximum extent. Practice shows that the comprehensive technical measures for construction of the metro station can significantly reduce the blasting vibration and disturbance of surrounding rock, guaranteeing the safety of surrounding buildings and personnel. 2019 Vol. 56 (1): 185-191 [Abstract] ( 870 ) [HTML 1KB] [ PDF 2655KB] ( 1912 ) 192 Study on Disease Causes and Rehabilitation Schemes for the Taoping Tunnel on Houma-Yueshan Railway WANG Fei HU Lixue HU Yongzhan Since the operation of Taoping tunnel on Houma-Yueshan railway, the diseases occur frequently and have been developing intensely since starting in 2013, endangering traffic safety. With a systematic special survey on the diseases of Taoping tunnel, a comprehensive investigation and statistics were carried out regarding the disease type, section, scale and development in different phases by means of desk study of documents, in-tunnel investigation, ground survey, site visiting, geophysical prospecting, drilling prospecting and indoor tests, and it found out the tunnel diseases are affected by construction standard, engineering defect, weakness and swelling of surrounding rock, mined-out area and other factors. The different rehabilitation schemes were proposed, including rehabilitation at the window time, alternately rehabilitation by closing one tube, building of a new double-track tunnel, building a new single-track tunnel and enlarging excavation by closing one tube and so on. It concluded that a scheme of onetrack tube running and one tube closing is recommended for the existing tunnel rehabilitation and a one-tube twotrack tunnel system for the new built tunnel scheme. 2019 Vol. 56 (1): 192-199 [Abstract] ( 804 ) [HTML 1KB] [ PDF 2752KB] ( 1821 ) 200 Study on Safety Risks Management of the Road Tunnel underneath High-pressure Oil Pipelines LUO Chi1 LEI Junfeng2 SHI Jixun1 Based on the tunnel of east extension of Chengluo avenue at the Luodai ancient town, safety risks of the road tunnel underneath existing high-pressure oil pipeline during the construction and operation were analyzed and the countermeasures were proposed. The results of site monitoring and measuring show that the proposed countermeasures are practical, and the safe operation of oil pipelines is guaranteed during the construction of the tunnel. 2019 Vol. 56 (1): 200-204 [Abstract] ( 816 ) [HTML 1KB] [ PDF 1940KB] ( 1944 ) 205 Research on Comprehensive Construction Technology for Retaining Structure of Special-shaped Deep Foundation Pit in Inclined Hard Rock TANG Xiaorong1 ZHANG Liqun2 GUO Xi1 SHI Jinhui1 SUN Bole3 Aiming at the construction difficulties and hole deviation issuses of diaphragm retaining wall and bored pile in inclined hard rocks, the corresponding construction techniques of hole drilled by rotary drilling rig and trough constructed by piling machine, and bored hole drilled by down-the-hole drill rig + rotary drilling rig were proposed based on a theoretical and practical research, by taking the retaining structure construction of a deep foundation pit of a metro station as an example. The results show that: (1) in the construction of diaphragm retaining structure in hard rock, main holes are constructed with intervals by rotary drilling rig, and accessory holes are constructed by piling machine, which improves the construction speed of retaining structure; (2) It is difficult to construct the bored pile in the hard rock, and the quincunx bores are drilled by down-the-hole drill rig and then followed by rotary drilling, which greatly increases the construction speed; (3) by adjusting the perpendicularity of the rotary drilling rig and the down-the -hole drill rig, the inclination of troughs and holes is avoided, guaranteeing the perpen? dicularity in the inclined rock mass; (4) the technical parameters of rotary drilling rig should be optimized to guarantee the perpendicularity during the rotary drilling construction in inclined hard rocks. 2019 Vol. 56 (1): 205-208 [Abstract] ( 858 ) [HTML 1KB] [ PDF 1107KB] ( 1859 )

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