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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2019 Vol.56 Issue.6 Published 2019-12-25 1 Study on the Key Techniques for Comprehensive Control of Heat Harm of the Deep-buried and Super-long Tunnel with High Ground Temperature FAN Lei It is of high risks to build super-long tunnels in the area with high ground temperature which brings great challenges to the tunnel construction and operation. Based on the Gaoligongshan tunnel on Dali-Ruili railway,the longest under construction in China, the key techniques for comprehensive control of heat harm of the superlong tunnel are studied, the standard of thermal environment control and the reasonable area of heat harm control are determined, a series of combined cooling methods like ventilation, refrigeration and geothermal water treatment are designed, and the supporting system of tunnel structure and anti-cracking measures under high ground temperature are proposed; the new construction materials suitable for high temperature environment are developed by indoor model test; a three-dimensional unsteady heat transfer model is established according to the theory of heat transfer,the temperature field under tunnel operation environment is simulated, and the cooling countermeasures of segmented longitudinal ventilation by using ventilation shafts during tunnel operation are worked out. 2019 Vol. 56 (6): 1-10 [Abstract] ( 785 ) [HTML 1KB] [ PDF 3743KB] ( 1923 ) 11 Study on the Key Techniques for Improving Working Environment of the Extra-long Highway Tunnels in High Altitude Areas GAO Juru1 ZHANG Bo1 WANG Yao1 QU Haobo1 YAO Zhijun2 The extra-long Que′ershan road tunnel on the No. 317 national road has the characteristics of high alti? tude and geostress, low temperature, low atmospheric pressure and oxygen, and the working environment inside the tunnel is harsh due to low efficiency of ventilation at the initial stage of construction and the emitted hazardous gas from internal combustion engines, affecting health of the constructers and threatening the personal safety. A study on the construction ventilation, oxygen generating and supplying and the techniques for reducing hazardous gas emission from internal combustion engine is conducted. Finally the key techniques for improving the working environment of extra-long road tunnels in high altitude area are proposed. 2019 Vol. 56 (6): 11-18 [Abstract] ( 745 ) [HTML 1KB] [ PDF 2345KB] ( 1610 ) 19 Research on Design Parameters for Shield Tunnel Lining Structure with Quick Connectors LIU Xian1 LI Haitao1 GUAN Panfeng2 YANG Zhihao2 Mechanical performances of segment joints are the key factors affecting the design parameters of shield tunnel lining structures, and the performances of the joints using quick connectors are not yet clear. With reference to the research and application cases of quick-connectors used for the shield tunnel lining in foreign countries, the key parameters like bending stiffness of longitudinal joints, shear stiffness of longitudinal and circumferential joints are studied by load tests on segment joints adopted in Shanghai natural gas pipeline project. A beam-spring method based analysis model for three segment lining rings with the staggered joints is established and the specific value ranges of the key model parameters are given considering the test results. Finally the stiffness reduction factor and bending moment transfer coefficient of the modified routine model of the lining structure using quick-connectors are proposed based on the calculation and comparison. 2019 Vol. 56 (6): 19-26 [Abstract] ( 700 ) [HTML 1KB] [ PDF 2976KB] ( 1528 ) 27 Study on Effect of Backfilling Grouting Thickness on Anti-floating of the Shield Tunnel LI Qiang1 GAN Penglu2,3 ZHONG Xiaochun4 Sand liquefaction will occur and result in tunnel uplift and even damage under the effect of earthquake when the shield tunnel passes through sandy soil stratum. The dynamic response of the surrounding liquefied strata before and after backfill grouting of the shield tunnel is studied by shaking table model test and numerical simulation, and it shows the main damage pattern of the shield tunnel is liquefaction induced uplift. Backfill grouting can ′t significantly alleviate the liquefaction tendency of subsoil, but the uplifting displacement of the tunnel model can be remarkably reduced if peak acceleration keeps unchanged. The numerical simulation and test results show that the sand liquefaction firstly occurs at the surface and shallow soil layer, and the sand liquefaction degree gradually decreases with the increase of depth, that is to say increase of tunnel buried depth is conducive to reducing liquefaction degree. Integrity is formed by backfilling grouts and tunnel structure and this increases the overlying effective pressure indirectly and can offset the uplift induced by foundation liquefaction. For the shield tunnel with a diameter larger than 6.2 m, obvious anti-uplift effect will be obtained if the grout penetration radius is larger than 1.0 m in condition of grouting reinforcement. 2019 Vol. 56 (6): 27-35 [Abstract] ( 717 ) [HTML 1KB] [ PDF 4960KB] ( 1607 ) 36 Analysis on the Genesis of Gas in the Tunnel with Oil and Gas and Its Safety Management LI Rongxin1 CHEN Huawei2 ZHOU Songyuan1 LIU Xinping1 The Hongyanxi tunnel is the first highway tunnel in China, which is rich in oil and gas. In order to solve the safety problem of gas and oil during tunnel excavation, on-site detection and carbon isotope laboratory test of gas samples are conducted regarding the rocks at working face, gas and oil-soluble substances. The research results show that the genetic type of oil and gas of this tunnel is of low maturity and this tunnel is unconventional type with high contents of gas. Safe breakthrough is guaranteed for this tunnel with high risk source by adopting comprehensive measures of gas prevention and control training, emergency rescue drill, safety management process normalization, ventilation system improvement, monitoring and control system establishment and special treatment of major risk sources. 2019 Vol. 56 (6): 36-40 [Abstract] ( 712 ) [HTML 1KB] [ PDF 2026KB] ( 1702 ) 41 Research on the Distribution Characteristics and Migration Law of Shallow Natural Gas of Longquanshan Tunnel on Chengdu Metro TANG Bin The shallow natural gas bearing reservoir of the Longquanshan tunnel of Chengdu metro is the sand? stone reservoir of Jurassic Shaximiao formation, and its distribution characteristics are affected by the Wolongmiao syncline, Longquanyi anticline and Ma′anshan fault structure. Based on an analysis of the geological drilling test, it is found that the shallow natural gas of Longquanshan tunnel has close correlation with sandstone bed, natural gas migrates from the sandstone reservoir and fractured zone of fault to the tunnel excavation space, and the preventive measures are designed based on two areas of high gas risks and three areas of low gas risks; the gas is mainly distributed at the place nearby the three geological structures, especially the gas concentration is high at the deep sandstone stratum of the west wing of Wolongmiao syncline. 2019 Vol. 56 (6): 41-46 [Abstract] ( 654 ) [HTML 1KB] [ PDF 3441KB] ( 1338 ) 47 Physical Simulation of Tunnel Advance Geological Prediction by Transient Electromagnetic Method QIN Liang1 ZHANG Qingchao2 The model experiment is designed based on the physical simulation similarity criterion, and the total sur? rounding space, homogeneous medium, tunnel space, anonymous body and metal disturbance mass are simulated by water channel, brine, plastic slot, copper plate and iron weight, focusing on the influence of tunnel space, metal disturbance mass and anomalous body itself on tunnel advance geological prediction by transient electromagnetic method.The experiment results show that tunnel space has slight effect on secondary electromagnetic response value and barely little effect on decay rate of secondary electromagnetic response; the prediction results will be significantly affected due to presence of metal disturbance mass, which results in increase of induced electromotive force and the presence pseudomorphism of low resistance anomalous body; the induced electromotive force exponentially decays with an increase of distance between anomalous body and pick-up coil during the physical simulation of anomalous bodies in different positions; the feasibility of application of transient electromagnetic method in tunnel advance geological prediction is verified. 2019 Vol. 56 (6): 47-51 [Abstract] ( 709 ) [HTML 1KB] [ PDF 2625KB] ( 1411 ) 52 Research and Development of the Embedded Rubber Waterstops Reinforced with Horizontally Built-in Steel Plates ZHANG Minqing LI Shu LIU Juncheng The prominent quality problems of construction joints of railway tunnel linings are mainly represented by displacement, twisting, cockling of the embedded rubber waterstops during concrete pouring and this results in the risks of lamelliform concrete at construction joints and chip off-falling, endangering railway traffic safety. However the visual effect of tunnel linings is affected if the lamellated concrete is removed. In view of this, the embedded rubber waterstop reinforced with horizontally built-in steel plate is developed, and the problems concerning complex site installation and management are radically solved by the industrialized steel plate embedded in the rubber waterstop, without changing the material performances of rubber. The field test shows this new waterstop is worth being promoted and applied attributed to the characteristics of easy use, good installation quality, high efficiency and low cost. 2019 Vol. 56 (6): 52-56 [Abstract] ( 675 ) [HTML 1KB] [ PDF 2589KB] ( 1422 ) 57 Study on Creep Test and Empirical Damage Model of Artificial Frozen Soils MA Shilong WU Mingying YAO Zhaoming It is important to understand the creep characteristics of frozen soils to evaluate the stability of frozen walls during freezing construction. The uniaxial compressive and creep tests are conducted on the clay stratum of a mine in Shanxi province under different freezing temperatures, and the law of creep varying with freezing temperature and loading stress is obtained. Based on an analysis of the characteristics of Kachanov′ s theoretical damage model and empirical creep model of artificial frozen soils, a theoretical-empirical creep model of artificial frozen soils is established. Through a comparative analysis on the calculated values of the model and the creep test results of artificially frozen clay, it is found that the curve of model calculations and the curve of experimental data fit very well, and both the curves show the process of initial elastic deformation, gradual decrease of strain acceleration and zero acceleration; the established model reflects the creep characteristics of deep artificial frozen soils in different stages. 2019 Vol. 56 (6): 57-62 [Abstract] ( 702 ) [HTML 1KB] [ PDF 1752KB] ( 1604 ) 63 Study on Earth Pressure Difference Law of Load Relieving Structure of the Rectangular and Arched High-filled Loess Open Cut Tunnels MA Li1 LI Sheng2 WANG Qicai2 YU Bentian2 LIU Yapeng2 WANG Qingshi2 The high-filled open cut tunnel causes larger force applied on the structure and endangers its safety. Considering EPS induced load reduction, section type and foundation stiffness, the change rules of earth pressure and soil displacement on the top of open cut tunnel varying with the filling height are studied by model test and numerical simulation. The results show that the change of earth pressure on top of the load relieving structure of highfilled loess open cut tunnel is of nonlinear with filling height, the open cut tunnel with arched section is better than the rectangular one and the open cut tunnel with flexible foundation is better than that with rigid foundation regarding the load relieving effect; the earth pressure increases at first and decreases later and finally tends to be stable from the center at top to the two sides of open cut tunnel with rectangular section, the peak earth pressure occurs at the boundary of both sides of open cut tunnel, the difference between the peak earth pressure and the earth pressure at the central point of tunnel crown decreases due to the EPS induced load relieving and flexible foundation; the vertical earth pressure decreases at first and tends to be stable from the center to the two sides of open cut tunnel with arched section and the peak earth pressure occurs at the central point of tunnel top. The curve pattern of soil mass settlements at the top of the open cut tunnel with rectangle section changes from the "double V" before load relieving to the "U" distribution after load relieving. A numerical simulation analysis on the test process is conducted, and the average error of the two calculation results is 11.0%, which validates the correctness of the experiment data and the rationality of the calculation parameters. Finally the differences of soil arch effects of the load relieving structures of open cut tunnels with different section types and foundation stiffnesses are discussed in terms of lateral stress of fillings. 2019 Vol. 56 (6): 63-69 [Abstract] ( 695 ) [HTML 1KB] [ PDF 3206KB] ( 1256 ) 70 Analysis of Deformation Stability Reliability of Tunnel Surrounding Rocks Based on Vector Projection Response Surface Method GUO Jian1,2 YANG Zhiguo1,2 KANG Fengxue3 Stability of rock mass deformation is an important factor to ensure the safety of tunnel construction, the deformation stability function of surrounding rock is of implicit or highly nonlinear due to many factors affecting the stability of surrounding rock deformation, while the calculation can be simplified and the accuracy can be guaranteed by using vector projection response method. In order to judge the stability of surrounding rock by reliability theory, the performance function of rock mass deformation stability of the circular tunnel is established by taking the analytical solution of rock mass displacement of the circular tunnel as the rock mass displacement function which is obtained by taking the Mohr-Coulomb strength theory as the rock mass yield condition, and taking the crown settlement as the ultimate displacement of rock mass deformation when the rock mass surface of unsupported circular tunnel reaches shear plastic limit. Using the vector projection sampling method, the response surface function is solved by determining the sampling points based on gradient projection of response surface function, the reliability indexes of rock mass deformation stability are calculated by first-order second-moment method, a comparison with the results calculated with Monte Carlo method is conducted, and the reliability of tunnel rock mass deformation stability is evaluated. 2019 Vol. 56 (6): 70-77 [Abstract] ( 670 ) [HTML 1KB] [ PDF 1712KB] ( 1259 ) 78 Study on Stability of the Support System with Anchor Bolts and Shotcrete under Overbreak and Underbreak Conditions LIU Mingcai The overbreak and underbreak caused by tunnel construction will change the stress state of surrounding rocks and even affect the stability of surrounding rocks. The boundary of surrounding rocks is divided into three categories, namely parallel overlay, bottom overlay and complete overlay according to the section contours of tunnel with overbreak and underbreak and the thickness of shotcrete layer; based on the elastic thick-wall cylinder theory, the stiffness of equivalent thick-wall cylinder and the maximum support pressure are deduced; the calculation formula of stiffness and the maximum support pressure of the composite support structure with shotcrete and anchor bolts are established on the basis of parallel system of anchor bolts and shotcrete; stability of the Lianhuashan No. 2 tunnel is analyzed by convergence-confinement theory, and the results show the stability analysis of surrounding rocks considering the effect of overbreak and underbreak is more in accordance with the actual situation, verifying this analysis method. 2019 Vol. 56 (6): 78-84 [Abstract] ( 668 ) [HTML 1KB] [ PDF 2533KB] ( 1277 ) 85 On Mutual Dynamic Effect of Tunnel Blasting Construction Adjacent to Existing Tunnel YU Jianxin1 LIU Huanchun2 WEI Haixia1 CHEN Chen2 Construction of the new tunnel could result in deformation and even damage of the surrounding rocks and lining structures of existing tunnel when two tunnels are very close. Taking a large-span highway tunnel approaching a small existing tunnel as the background, LS-DYNA explicit dynamic numerical simulation method is adopted to study mutual effect of tunnel blasting construction adjacent to existing tunnel. The results show that the vibration velocity component in the new tunnel is perpendicular to the tunnel contour and the horizontal component of the vibration velocity at the existing tunnel side facing the blasting is the largest; the effect of surrounding rock type on blasting vibration velocity is mainly at the new tunnel side approaching the existing tunnel and it has little effect on the vibration velocity in the existing tunnel; the explosive dosage and tunnel span have significant effect on the new tunnel floor near the blast source and the clear distance has large effect on the new tunnel at the side approaching the existing tunnel; explosive dosage increase, reduction of clear distance and span will cause increase of the vibration velocity of the existing tunnel to certain extent; regardless of the relative position of two tunnels, the maximum vibration velocity of the new tunnel occurs at the side approaching the existing tunnel, the maximum vibration velocity of the existing tunnel occurs at the side facing the blasting, and the vibration caused by blast which working face passes through above the existing tunnel is larger than that which the working face is far away from the existing tunnel;the existing tunnel has certain amplification effect on the vibration velocity of the new tunnel. 2019 Vol. 56 (6): 85-92 [Abstract] ( 723 ) [HTML 1KB] [ PDF 3742KB] ( 1300 ) 93 Exploration on the Equilibrium Evaluation Model for the Health Status of Road Tunnels XIE Liguang1 YANG Qun2 SHENG Yong1 TANG Fujun1 Aiming at the problems existing in the current evaluation methods for the health status of road tunnels, a equilibrium evaluation model is proposed which evaluates the health status of the road tunnels based on the distribution equilibrium of relevant physical and mechanical parameters, and the degree of equilibrium is defined by the coefficients of variation and imbalance. The research shows the disequilibrium of pressure distribution of surrounding rocks has little effect on safety of tunnel structure while the equilibrium of ground resistance distribution has significant effect on safety of tunnel structure under condition of uniform distribution of adequate ground resistance; in order to ensure the safety of tunnel structure, the proper coefficients of ground resistance variation and disequilibrium should be no more than 0.5 , 0.3 respectively and the coefficients of variation and disequilibrium must be no more than 0.7 and 0.6 respectively within the scope under the tunnel haunch. 2019 Vol. 56 (6): 93-98 [Abstract] ( 677 ) [HTML 1KB] [ PDF 2035KB] ( 1371 ) 99 Analysis of the Effect of Underground Coal Mining on the Bayueshan Tunnel SUN Haoxuan1 LI Peixian1 CUI Ximin1 YAO Dehua2 XIAO Wu3 Affected by the mining of Xinsheng coal mine and Changrong coal mine, some cracks and chip off-falling occur at the Bayueshan tunnel of Chongqing-Chengdu expressway. In order to understand the impact of coal mining on the tunnel, the tunnel displacement and deformation caused by underground mining in different stages are calculated with probability integral method, the causes of tunnel and pavement damages and deformation of the left tube after full mining of coal resources are analyzed by taking the left tunnel tube as an example, and the recommended measures for tunnel maintenance and safety are proposed. The predicted results are basically consistent with the actual conditions of tunnel and pavement damages. 2019 Vol. 56 (6): 99-106 [Abstract] ( 771 ) [HTML 1KB] [ PDF 2500KB] ( 1182 ) 107 Measurement and Analysis of Deep Foundation Pit Excavation in Deep Soft Soil Stratum ZUO Zhuo1 FU Helin2 ZHANG Jiabing2 LIN Rui 2 GONG Jiabin3 Construction of deep foundation pit will have adverse effect on the safety of surrounding soil mass, re? taining structure and environment. Monitoring and measurement of ground surface settlement, building settlement,deep horizontal displacement of wall, horizontal displacement and vertical displacement at the top of wall and axial force of strut are conducted for the deep foundation pit of the Foshan-Dongguan intercity railway, and a thorough analysis on the monitoring results is taken. The results show that: at the initial stage of foundation pit excavation, the lateral displacement of wall presents cantilever bending shape, the maximum horizontal displacement occurs near the top of wall and it goes downward and occurs at the bottom of foundation pit with the increase of excavation depth;the vertical displacement develops rapidly and the horizontal displacement is about 65% of the total displacement at the top of wall within 60-120 days of foundation pit excavation, the displacement is more and more slowly after 120 days of foundation pit excavation; the axial force of strut increases with the increase of depth of foundation pit exca? vation, and the axial force of all struts reaches the maximum value after the completion of foundation pit excavation. 2019 Vol. 56 (6): 107-113 [Abstract] ( 698 ) [HTML 1KB] [ PDF 3941KB] ( 1299 ) 114 Study on the Influence of the Construction of Large-section Metro Station on Lateral Friction Resistance of Adjacent Pile Foundation CHEN Zhuo1,2 KONG Chao3 The construction of metro station underneath or parallel to pile foundation of the bridge causes large area excavation unloading at the side of bridge pile foundation. The operation safety of existing bridges will be threatened due to lateral friction resistance decrease caused by metro construction adjacent to friction pile. A calculation formula of lateral friction resistance friction pile foundation adjacent to metro station is deduced by simplifying the force on existing friction pile foundation as four parts and it is verified in the construction of North Taipingqiao Station of Beijing metro line 19. The results show the maximum lateral friction resistance loss ratio is 42.8% when the excavation depth of metro station is larger than the length of pile foundation; the excavation width of metro station has a little influence on lateral friction resistance loss; injection reinforcement of the soil mass around the pile foundation before construction can enlarge the internal friction angle with the proper range of 25°-30°. 2019 Vol. 56 (6): 114-120 [Abstract] ( 608 ) [HTML 1KB] [ PDF 2629KB] ( 1325 ) 121 Analysis on the Deep Soil Deformation Induced by Construction of Narrowlong Excavation Pit in Soft Ground Area LI Fulin1,2 Construction of narrow-long excavation pits in deep and thick soil ground has significant impacts on sur? rounding environments. A three-dimensional finite element model is established, the characteristics of soft soil deformation are simulated by a HS-Small constitutive model and the law of displacement development of adjacent deep soil is studied during construction of the narrow-long excavation pit. It is found that both vertical and horizontal displacements of adjacent soil mass are sensitive to the depth of excavation pit and they increase with an increase of excavation depth; the curve of lateral displacement of soil mass is of V or arch form and the position of the maximum lateral displacement is in accordance with the excavation depth; settlements are observed at the soil mass above excavation depth and heaves are observed at the soil mass below the excavation depth due to unloading effect of excavation; the support stiffness decreases if support is removed and new beam is not constructed immediately to replace it and this will result in lateral and vertical displacements of stratum. Due to the excavation spatial effect, the orders of lateral and vertical displacements of the monitoring points are the long side, short side and pit corner of excava? tion pit in terms of displacement magnitude. 2019 Vol. 56 (6): 121-127 [Abstract] ( 623 ) [HTML 1KB] [ PDF 2512KB] ( 906 ) 128 On the Design of the Four-tube Ten-lane Highway Tunnel Based on Passenger-Freight Division LI Yuwen1 LENG Xiqiao1 BAI Fan2 As for the highway tunnel with massive traffic flow or near the urban area, the lane numbers in tunnel are mostly the same as that of the roadways. However the specified operation speed in the tunnel is often slower than that of the roadway and it results in decline of traffic capacity in tunnel and traffic jam at tunnel entrance. Taking the Longquanshan tunnel of Tianfu airport highway for example, a multi-dimension analysis is conducted in terms of tunnel operation management speed, traffic capacity, construction feasibility and etc., a passenger-freight division based four-tube and ten-lane tunnel system is proposed, namely 2 lanes (freight wagons) +3 lanes (passenger cars)+ 3 lanes (passenger cars) +2 lanes (freight wagons), thus the tunnel has the same traffic capacity as that of roadway and the safety of tunnel construction and operation are ensured. 2019 Vol. 56 (6): 128-133 [Abstract] ( 611 ) [HTML 1KB] [ PDF 1616KB] ( 1512 ) 134 Study on the Design of Dimming Structure for the Road Tunnel Entrance WANG Xiang LI Fengwei YANG Ke Big differences of illumination intensities inside and outside of tunnel entrance is the main reason of traffic accident, and reasonable transition of illumination difference is available to guarantee traffic safety with dimming structure installed at tunnel entrance. Based on an investigation and study on the dimming structures for the tunnel entrance in China, the types, cross-sectional forms and application scopes of the dimming structures are summarized. The illumination test is designed to study the change rate of visual adaptability illumination when drivers arrive at the tunnel entrance, and a method to calculate dimming structure length is proposed considering the relevant tunnel lighting specifications. A dimming structure model is established by using luminous environment analysis software Ecotect and luminous environment simulation is carried out. The results show that the length of dimming structure installed at tunnel entrance should be 58 m at least when the drivers drive to tunnel at a speed of 100 km/h in condition of 60 000 lux ambient illumination. 2019 Vol. 56 (6): 134-139 [Abstract] ( 544 ) [HTML 1KB] [ PDF 1422KB] ( 1276 ) 140 Research on the Main Design Parameters of the Inclined Shaft with Trackless Transport in Railway Tunnelling ZHANG Xuzhen Inclined shaft with trackless transport mode is widely applied in the railway, highway, hydraulic engi? neering and mines attributed to the advantages of high efficiency, low input and easy maintenance, but a unified standard for the design parameters of longitudinal gradient and inner contour of inclined shaft is not available at present time. By reference to the design regulations on gradient and inner contour of inclined shaft adopted in different industries, the maximum gradient and basic inner contour dimensions of inclined shaft with trackless transport in railway tunnelling are proposed by theoretic calculation and formula derivation, and the design principles of clear width and clear height as well as the interval of passing bay and flat slope section are determined for the inclined shaft with trackless transportation. 2019 Vol. 56 (6): 140-144 [Abstract] ( 629 ) [HTML 1KB] [ PDF 974KB] ( 1493 ) 145 Study on the Shaft and Inclined Shaft Scheme for the Extra-large Xianrendong Tunnel PENG Jinsong SHI Jixun It is necessary to set shaft and inclined shaft for the highway tunnels being longer than 7 km to meet ven? tilation requirements. In light of a research on the ventilation methods for the existing highway tunnels more than 7km long, it is found that there are some problems for the setting of shaft and inclined shaft. Taking the Xianrendong tunnel for example, the basic ideas and method for the design of shaft and inclined shaft of the extra-long highway tunnel are proposed. 2019 Vol. 56 (6): 145-150 [Abstract] ( 598 ) [HTML 1KB] [ PDF 2338KB] ( 1445 ) 151 Analysis and Evaluation on the Effect of Comprehensive Geological Survey of the Extra-long Western Qinling Tunnel GAO Qinyun The geological conditions of the extra-long West Qinling tunnel on Lanzhou-Chongqing railway are complex which is characterized by karst, active faults and high geostress. The characteristics of surrounding rocks,structure, geostress, groundwater, karst and so on are evaluated and predicted by comprehensive geological survey-The effect of geological survey is evaluated and the reasons for the difference between survey results and actual conditions disclosed by construction are analyzed based on a comparison with the geological conditions obtained by tunnel construction. The suggestions are proposed such as focusing on the analysis and research of the background of regional geologic structure, implementing drilling verification and carrying out hydrogeological pumping test for the long deep-buried tunnels. 2019 Vol. 56 (6): 151-156 [Abstract] ( 655 ) [HTML 1KB] [ PDF 1848KB] ( 1359 ) 157 Application of Lining Defect Prevention Techniques in Railway Tunnels in Operation LIU Jie1 DONG Wu2 GONG Chengming3 The defects of cavity at crown, lining cracking and chip off-falling, water seepage and leakage and so on in operated railways will endanger the safety of railway operation. The damage patterns of lining cavity and the advantages and disadvantages of the common remediation methods for the lining defects are analyzed in respects of theory and damage model. The prevention techniques by grouting with mould for lining defects are proposed to realize reinforcement and rehabilitation aiming at the lining defects of certain operated railway tunnel. The application effect shows that lining integrity is good, with the characteristics of short construction period and high efficiency. 2019 Vol. 56 (6): 157-161 [Abstract] ( 522 ) [HTML 1KB] [ PDF 3712KB] ( 1270 ) 162 On the Key Points of Tunnel Invert Heaving and Its Prevention Measures ZHANG Tiantao1 ZHANG Weiyi2 The mechanism of tunnel invert heaving is analyzed from the three aspects of natural environment, hu? man factors and disaster, aiming at the hazards caused by tunnel invert heaving. Three hypotheses for simplification of differential equation of thin plate buckling are proposed, the seven key points affecting tunnel invert heaving are summarized, the applicability of the inspection method for the seven key points is analyzed, and the corresponding preventive measures are summarized. Based on the invert heaving inspection of certain tunnel, the correctness of this study is verified to some extent. 2019 Vol. 56 (6): 162-166 [Abstract] ( 610 ) [HTML 1KB] [ PDF 759KB] ( 1577 ) 167 A Comparative Study of the Excavation Methods for the Large-span Intersection of Zizhi Tunnel in Hangzhou LIU Jingliang1 FANG Yuchao2 YE Xiaomu1 In light of the unfavorable geological conditions of urban tunnels with complex environments and high requirements of deformation control, it′s necessary to adopt proper construction method for urban tunnels. By taking the large-span Zizhi tunnel in Hangzhou as an example, different excavation methods like CRD method, double side drift method and reserved core method are compared regarding the advantages and disadvantages of above methods,the crown settlement, horizontal convergence and ground surface settlement of the large-span junction of this tunnel under different construction methods are especially analyzed by FEM model, and the rationality of reserved core method adopted in the construction of large-span Zizhi tunnel is verified by a comparison of the calculation values and the measured values. 2019 Vol. 56 (6): 167-172 [Abstract] ( 590 ) [HTML 1KB] [ PDF 2446KB] ( 1211 ) 173 Application of Blasting Techniques with the Reserved Smooth Blasting Layer in Full-face Construction of Large and Long Tunnels MA Chunde1,2 LIU Zelin1 ZHENG Jing3 LONG Shan1 ZHANG Jianqiu3 GUO Chunzhi1 As for the traditional smooth blasting of the large cross–section tunnel, it is hard to ensure that all pe? ripheral holes detonate simultaneously and there are a series of problems like low contour flatness and residual blasthole trace rate, large overbreak and underbreak, poor shaping quality and so on. Based on the East Tianshan tunnel,the blasting technique with the reserved smooth blasting layer is adopted to conduct full-face construction, and good smooth blasting effect is obtained by optimizing initiation sequence, network and parameters. The site test results show that the average linear overbreak is controlled within 15-25 cm which is reduced by 80% compared with traditional smooth blasting; the concrete consumption of primary support is reduced by 2.63 m3/m; and the parameters of practical cyclical advance rate, residual blasthole trace rate, unit explosive consumption and so on are significantly improved. 2019 Vol. 56 (6): 173-180 [Abstract] ( 577 ) [HTML 1KB] [ PDF 3197KB] ( 1883 ) 181 Ground Surface Grouting Techniques for the Railway Tunnel in Completely Weathered Granite Stratum LIU Shijie LIU Ze WU Jianhe ZHONG Youjiang Horizontal grouting reinforcement is the main method for the tunnel with buried depth over 40 m in soft surrounding rocks, but it has a great influence on construction organization in the tunnel. Based on the Daling tunnel of Meizhou-Shantou railway, the advantages and disadvantages of the grouting reinforcement schemes from ground surface and in the tunnel are compared, and an experimental study on the technology of surface deep-hole grouting reinforcement is carried out. The results show that the clear grout vein and good grout splitting effect as well as stable work face are obtained by using grouting technology of pressure-bearing steel sleeve valve tube to reinforce the deep-buried completely weathered and water-rich granite stratum, creating conditions for large-section tunnel excavation and realizing monthly advance rate of 70 m in the surrounding rocks of grade V. 2019 Vol. 56 (6): 181-186 [Abstract] ( 619 ) [HTML 1KB] [ PDF 1676KB] ( 1638 ) 187 Research and Application of the Construction Ventilation Techniques for Large Underground Cavern Group SUN Huixiang WANG Haiping NATM and mining method are often adopted in the construction of underground caverns, the pollutant produced by blasting at working face affects safety and occupational health of workers and restricts the advance rate.Based on the Baihetan hydropower station project, the design concepts of " three-in-one combination" and "design by stages" for the construction ventilation system are proposed, a three-dimensional unsteady turbulent field model is established, the characteristics and law of smoke emission during ventilation of complex underground cavern group are studied, special ventilation tunnel connecting to the main caverns is planned and an energy-efficient“ air supplying + air exhausting”ventilation system is formed, the frequency conversion fan is adopted to realize the optimal effect of mechanical ventilation based on use of natural ventilation. The numerical calculation and test results of pollutant concentration at site show that air distributes smoothly, the air velocity in the vertical shaft area is much larger than that near the cavern group, the emission paths of pollutant are working face, ventilation shaft and special ventilation adit, the pollutant produced by blasting can be fully discharged after 15 minutes of ventilation. 2019 Vol. 56 (6): 187-195 [Abstract] ( 598 ) [HTML 1KB] [ PDF 5313KB] ( 1563 ) 196 Countermeasures for the Shield Tunnel Passing through the Karst Area Overlying Soft Plastic Red Clays ZHUO Xuyang As for the karst area overlying soft plastic red clays, artificial dewatering and construction disturbance will cause collapse of karst ground and endanger tunnel construction and operation safety. The collapsing mechanism of the soft plastic red clay overlying karst area and the construction risks of shield tunnel in soft plastic red clay and the hard plastic red clay soil layer are analyzed, and the corresponding measures are established. The results show that dewatering destroys the equilibrium state among soil, fissure water and karst cave, leads to flowing of red clay into karst cave and the tunnel will subside with the subsidence of soft plastic red clay if the tunnel is located in soft plastic red clay stratum; after flowing of soft plastic red clay into karst cave, the soft plastic red clay layer collapses and a soil cave is formed between the plastic red clay layer and the hard plastic red clay layer and eventually the tunnel subsides due to low shear strength and cohesion, if the tunnel is located in hard plastic red clay layer; if the inclination of limestone surface is large and this will extend the settlement range of red clay. The following measures like filling of karst cave within the scope of high risks, reinforcement of the soft plastic red clay layer and adding of anti-sliding piles at the place with large inclination are adopted to manage the above mentioned risks. 2019 Vol. 56 (6): 196-202 [Abstract] ( 515 ) [HTML 1KB] [ PDF 5223KB] ( 1341 )

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