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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2018 Vol.55 Issue.6 Published 2018-12-25 Article 1 The Updated Concept of Conventional Tunnelling in Soft Surrounding Rocks WANG Jianyu In a perspective of modern tunnelling philosophy, some problems on conventional tunnelling in soft rock mass were discussed. The development process of rock mechanical behavior and deformation caused by excavation is attributed to the change course from yielding to discrete. Some effective control means were presented as well and the effect of advanced support system was evaluated. As to the deformation controlling technology for squeezing ground, the theory and design principle of yielding support system were introduced. 2018 Vol. 55 (6): 1-10 [Abstract] ( 842 ) [HTML 1KB] [ PDF 2118KB] ( 1576 ) 11 Comparative Analysis of Calculation Methods for Jacking Force of Jacking Pipes WANG Jialei JI Xinbo Jacking force is the most important parameter in jacking pipe engineering, and reasonable calculation of jacking forces plays an important role in safe and smooth pipe jacking construction. There are many calculation methods for pipe jacking force at present, and the calculation results may be affected to some extent by different calculation methods. For this reason, calculation methods of jacking force (frictional resistance) were collected and a comparative analysis was conducted with aspects to the advantages, disadvantages and applicabilities. The results show that as for the jacking force calculated by empirical formulae, the soil layer classifications corresponding to given frictional force per unit area and relevant factors to be considered are different, and the values of frictional force per unit area between pipe and soil in the same soil layer are also different; as for the jacking force calculated by theoretical formulae, the calculation methods for vertical earth pressure at crown are different and much effected by the pipe buried depth; as for the jacking force calculated by numerical simulation, the selected theories for the simulation program and the construction factors to be considered during simulation are different. 2018 Vol. 55 (6): 11-18 [Abstract] ( 1099 ) [HTML 1KB] [ PDF 2323KB] ( 2207 ) 19 Development of the Software for Calculating Tunnel Portal Structure Based on the Theory of Limit State Method HU Wei1 ZHAO Dongping1 TAN Xinrong1 GAO Yan2 The limit states of railway tunnel portal structure including compression, tensile, anti-overturning, antisliding and bearing capacity of foundation should be considered when portal structure is designed based on the probability limit state method. In order to evaluate the reliability of portal structure, the reliability index and limit state of bearing capacities of different limit states need to be calculated. The traditional methods generally use hand computation combined with MATTLAB, ANSYS, EXCEL and other softwares, which has low computation efficiency and poor practicality. In view of above problems, a calculating software for portal structure was developed based on the probability limit state method and Visual Basic platform, which realizes the function of rapid calculation of reliability index and limit state of bearing capacities under five limit states of portal structure, offers three methods to calculate the reliability index including JC method, fractile method and Monte-Carlo method. Moreover, the calculation results can be written in the EXCEL template file, greatly improving the efficiency of tunnel portal structure calcula? tion. The accuracy of the software is verified by comparing with the results of hand calculation. 2018 Vol. 55 (6): 19-25 [Abstract] ( 864 ) [HTML 1KB] [ PDF 2253KB] ( 1981 ) 26 Key Techniques for Lean Construction Management of the High Speed Railway Tunnels ZHI Peng SHI Tianyun WANG Wanqi XIE Yalong Improvements of management mode and application level of informationization techniques are the key factors to safe and efficient construction of the high-speed railway tunnels considering the complexity and diversity of construction techniques, unpredictable risk factors and varied geological conditions. In the paper it proposed a management mode for lean construction of high-speed railway tunnels, studied the in-depth integration and application of key technologies of BIM, advance geological prediction, tunnel surrounding rock measurement, 3D laser scanning, etc. in the lean construction management of high-speed railway tunnels, and developed the light portal APP and cloud-based information management system. Through the verification of practical engineering application, it realized good monitoring of key risk resources in tunnel construction, redline control for key tasks and effective management of safety and quality, increased efficiency of collaborative operation of all parties involved and reached the goal of lean construction and management. 2018 Vol. 55 (6): 26-32 [Abstract] ( 860 ) [HTML 1KB] [ PDF 5114KB] ( 2435 ) 33 Design and Practice of Cloud Computing Platform for TBM Operation Information YU Taizhang1 LI Jianbin2 JING Liujie1,3 XU Shoutian1 XU Jian′an1 The problems of TBM construction data loss, information barriers and absence of data mining have con? strained the advancement of basic technologies in TBM field. Aimed at building a cloud computation platform for TBM operation information, a new concept of 3B, i. e. Born by digit, Born in format and Born to the cloud, was presented, the issues of information acquisition, transmission and storage during TBM operation were solved, and massive heterogeneous information intelligent transmission system and big data warehouse of TBM group were established. A structure model of cloud computation platform was designed by taking Hadoop system as ecosphere, and a cloud computation platform was built to deploy related algorithm, realizing on-line monitoring and data sharing, furthermore the data law mining of interaction of rock mass versus TBM machine was conducted based on big data technique, exploring the development direction of the information platform. 2018 Vol. 55 (6): 33-41 [Abstract] ( 813 ) [HTML 1KB] [ PDF 4905KB] ( 2242 ) 42 Construction of Early Warning Control Platform for Tunnels and Subway Engineering CHEN Tao Based on an introduction to the construction and application of the early warning control platform for the tunnel and subway engineering, an overall analysis of the related data during tunnel and subway construction was conducted in order to give a better reference for the site construction, to guarantee safe and rapid qualified construction, and to improve management efficiency. Based on red line control, deformation thresholds of surrounding rock,allowances of construction material and advanced geological prediction, a dual early warning system with automatic trigging and manual prejudging was adopted to control the quality of tunnels and subways and to guarantee safe construction; through the platform a centralized management is realized, all the construction information and effective data are transmitted instantaneously by internet, decreasing management cost and increasing work efficiency. 2018 Vol. 55 (6): 42-52 [Abstract] ( 776 ) [HTML 1KB] [ PDF 5563KB] ( 1919 ) 53 Back Analysis of Surrounding Rock Mechanical Parameters of Underground Caverns Based on Genetic Algorithm ZHANG Jixun1 YANG Fan2 REN Xuhua1 ZHANG Daofa3 Surrounding rocks are the main bearing structure of underground caverns, and mechanical parameters used in design and analysis affect the result reliability directly. Based on the monitoring data of surrounding rocks of a water diversion tunnel and genetic algorithm, secondary development of software ABAQUS was conducted, related genetic algorithm was programmed to back analyze the mechanical parameters of surrounding rocks of underground caverns, then a comparison between the calculated parameters and the designed parameters was taken to discuss the rationality of the designed parameters. The results show that the inversion values are larger than the designed ones,and the displacements calculated by the inversion parameters are smaller than that of the original parameter values,showing that the parameters adopted in design are safe. The analysis results prove that the method proposed in this paper is available for parameter analysis in similar projects. 2018 Vol. 55 (6): 53-58 [Abstract] ( 848 ) [HTML 1KB] [ PDF 1171KB] ( 1869 ) 59 A Sampling-Based Probabilistic Prediction Method of Rockbursts in Deep-buried Tunnels LIU Haitao1 ZHOU Hui2 LU Jingjing2 HU Dawei2 YANG Fanjie2 With the increase of depth of underground works, lots of rock engineering are threatened by rockburst di? sasters. The study of rockburst prediction in deep tunnels is of big significance to controlling disasters during construction and determining construction parameters. However, rockburst events occur randomly and the randomness of rock mechanical parameters caused by the inhomogeneity of actual rock mass is one of the main factors leading to the randomness of rockbursts. A sampling-based probabilistic prediction method of rock bursts in deep tunnels is proposed based on the method combining reliability theory with numerical simulation. Mechanical parameters of rock mass are considered as stochastic variables, and the distribution types and numerical characteristics are obtained based on indoor tests and Bayes method; a group of numerical calculation sample are constructed by using Monte Carlo method of reliability theory; a numerical analysis of sample and a statistical analysis of numerical calculation results are carried out, the probability of rockbursts is obtained. An analysis and prediction of rockbursts occurred in branch tunnel F in the No.3 test tunnel of Jinping II hydropower station is conducted by using the sampling-based probabilistic prediction method. The results show that simulation results are consistent with actual rock? bursts, indicating that this prediction method is convenient and practical and can be taken as a useful references for prediction of rock bursts in the deep tunnels. 2018 Vol. 55 (6): 59-66 [Abstract] ( 932 ) [HTML 1KB] [ PDF 2431KB] ( 1734 ) 67 A Preliminary Study on the Law of Ground Settlement Caused by Shield Tunnelling Based on the Stratum Characteristic Value MS WANG Tianbiao1 JIA Cangqin2 Based on an analysis of monitoring data of surface settlement in the construction of a shield running tunnel of Beijing metro, an improved hyperbolic model was proposed to fit the ground subsidence law, and the characteristic factor MS was used to evaluate the stratum under the condition of shield construction. The relationship between stratum parameters and surface settlement was studied, with the results indicate that the surface settlement caused by shield construction complies with hyperbolic distribution and it is basically stable at 30 days, the larger the value of MS is, the better the conditions of the stratum is and the smaller the settlement is; a certain correlation exists between the parameters of improved hyperbolic model and the characteristic value MS. 2018 Vol. 55 (6): 67-72 [Abstract] ( 811 ) [HTML 1KB] [ PDF 1529KB] ( 1822 ) 73 Estimation Method for Ground Settlements of the Karst Tunnel in Soil Surrounding Rock WEN Shi Water seepage of a karst tunnel section in soil surrounding rock is prone to surface subsidence. Considering the settlement caused by descending of water level due to water leakage, a method of surface settlement estimation under steady seepage of phreatic water was proposed. Based on the seepage and consolidation theory, the changes of dead-weight and seepage effective stress of soil unit in surrounding rock was analyzed in condition of water seepage,and the settlement zone of surrounding rock was divided by taking the funnel curve of precipitation as the boundary line. A two-dimension plane was established based on the excavation cross section and the estimation formula for surface settlement due to seepage effect was deduced by means of double integral. On the basis of Yaozhai tunnel of Liuzhai-Hechi Expressway in Guangxi Zhuang Autonomous Region, the surface settlement of soil surrounding section was predicted by field measurement and formula estimation respectively. Facts and figures show that the measured values are mainly consistent with the estimation ones, while the measured values are larger than the estimation ones within the scope 3 m away from the excavation face along the horizontal radial direction. 2018 Vol. 55 (6): 73-79 [Abstract] ( 884 ) [HTML 1KB] [ PDF 2437KB] ( 1699 ) 80 Effect of Sequential Excavation of the Second Tunnel Tube on Transverse and Longitudinal Ground Settlements of the First Tunnel Tube in Parallel Tunnels YUAN Shaodong1 YANG Lin2 HUANG Jian2 As an economical and effective tunnel structure system, the parallel tunnel layout pattern is becoming one of the main tunnel structures in underground rail transit design. Since the applied force is complicated and various factors involved are mutually affected, it is urgent to understand the law of ground surface settlement induced by tunnel excavation. Based on FEM simulation and the measured surface settlement data of Qingdao metro, the evolution laws of settlement rate and range in transverse and longitudinal directions of the first tunnel tube were analyzed,and the deformation rules of original surface settlement trough due to the sequential construction of the second tunnel tube were revealed. The study shows that because of the influence of excavation parameters and geological paraneters,the maximum settlement point of original transverse settlement trough offsets to the symmetric point of two tunnels in specific velocity rate, and the variation of original longitudinal ground settlements at various points transmit along the excavation direction of second tunnel tube in a form similar to fluctuation with the characteristics of settlements being closely related to the distance from the second tunnel tube. 2018 Vol. 55 (6): 80-86 [Abstract] ( 944 ) [HTML 1KB] [ PDF 4040KB] ( 2038 ) 87 Sensitivity Analysis of the Influence of External Wall Insertion Ratio on Deformation of Pit-in-Pit HOU Xinyu YUAN Jiaojiao LIN Yanling Adopting Hardening-Soil finite element model based on soil unloading conditions, the influence of ex? ternal wall insertion ratio on deformation of retaining structure and soil was studied taking the foundation pit of a metro transfer station of Suzhou metro line 1 as background. The results show that the maximum lateral displacement of external wall decreases with an increase of insertion ratio within the range of 30-35 mm, and the lateral deformation at the foot of wall increases significantly in a linear form; the lateral deformation at the top of internal wall obviously increases linearly, while the maximum of lateral wall deformation of wall body increases slowly and there is almost no change at the bottom of wall; the uplift at the internal pit bottom is more than 90 mm and it is slightly effected by the insertion ration of external wall while the uplift at the external pit bottom is more than 70 mm and it increases with an decrease of the distance away from the external wall; soil mass settlement at the back of the external pit is obvious and it decreases with an increases of insertion ratio of external wall within the range 14 m away from the external wall, and the settlement reaches the maximum when the insertion ratio of external wall is 0.25 while the tendency of settlement develops reversely when the distance from the external wall is beyond 14 m. To en? sure the safety and reduce environmental impact, it is significant to determine a reasonable insertion ratio of external wall regarding the pit-in-pit excavation. 2018 Vol. 55 (6): 87-93 [Abstract] ( 828 ) [HTML 1KB] [ PDF 3086KB] ( 1900 ) 94 Contrastive Analysis of Working Face Stability in Cases of Climbing Excavation and Horizontal Excavation HAO Zhitao1,2 CAO Wufu1,2 WANG Ting1,2 Restricted by site and construction period of ancillary structure of metro project, climbing excavation is often adopted. In order to determine tunnel face′s stability, the stabilities of working face in the cases of climbing excavation and horizontal excavation were analyzed by theoretical analysis and numerical simulation. With upperbound limit analysis, the affected scope and positions of failure zone were compared; the position of equivalent strain zone and the law of horizontal displacement changes were studied by simulation analysis. The results show that the scope of failure zone caused by climbing excavation was slightly larger than that by horizontal excavation and the position of affected zone is slightly lower than that by horizontal excavation; the horizontal displacement caused by climbing excavation within a scope of 0-1/3 height of tunnel face is slightly larger than that by horizontal excavation while it is slightly smaller beyond the scope of 0-1/3 height of tunnel face; the maximum horizontal displacements in the cases of climbing and horizontal excavation both occur at the place where is 1/3 height of work face and the de? formation of work face in the case of climbing excavation is not larger than that of horizontal excavation; the work face stabilities are mostly the same in the cases of climbing and horizontal excavation without regard to advanced support, and the work face stability is to be guaranteed with proper advanced support. 2018 Vol. 55 (6): 94-100 [Abstract] ( 1084 ) [HTML 1KB] [ PDF 3005KB] ( 1674 ) 101 Study on Mechanical Characteristics and Safety of Deep-buried Highway Tunnel Lining under External Water Pressur DING Yanping1,2,3 XU Linsheng1,2 With increase of requirements for environmental protection in recent years, the concept of "preferred blocking and limited drainage" has been put forward for the water-rich tunnels, and it′s necessary to fully consider the capability of water pressure resistance of the lining structure of water-rich mountain tunnels. Based on the Chuntianmen tunnel, it analyzes the structure of water-resistant lining under bearing of full water pressure by a "loadstructure" model, and its mechanical characteristics were obtained. The results show that the quasi-round lining structure can bear the load of external water pressure very well; the safety factor is relatively small due to full-section of lining structure being under compression, and the maximum axial force and bending moment occur at the arch spring junction with small radius, so it′s also the weakest point of the structure 2018 Vol. 55 (6): 101-107 [Abstract] ( 845 ) [HTML 1KB] [ PDF 3690KB] ( 1912 ) 108 On Safety in Dismantling Temporary Strut of Super-large Tunnels with Double-layer Primary Support ZHANG Junru1 OU Xiaoqiang1,2 ZHENG Qiang1 GONG Yanfeng3 More and more multiple-track tunnels and super-large section tunnels have been built, and disman? tling of temporary strut is a weak point of the whole structure during force transfer when the secondary lining is constructed. It is significant to guarantee structure safety during dismantling of temporary strut. Little systematic research on safety in dismantling of temporary strut of the super-large section tunnel with double-layer primary support has been conducted, so the internal force and security of the two-layer primary support of the Xinkaotang tunnel were analyzed by a numerical analysis and site measurement, and it proves the effect of two-layer primary support on the safety during strut dismantling. The research results indicate that: (1) with constant support thickness and one-time longitudinal dismantling length, the safety factor of secondary primary support is larger than that of the first primary support, and the safety factor of the first primary support is larger than that of the single layer primary support. Change range of safety factor for the first primary support is smaller than that of the single-layer primary support, and the safe factor for the single-layer primary support is smaller than that of the secondary primary support; (2) with the same support pattern, the safety factors increase firstly and then decrease with an increase of the onetime dismantling length. The calculated results of various cases show that the reasonable one-time dismantling length for this project is about 9 m. 2018 Vol. 55 (6): 108-116 [Abstract] ( 886 ) [HTML 1KB] [ PDF 4471KB] ( 1681 ) 117 Study on the Protective Measures for the Shallow Foundation Houses Adjacent to Deep Foundation Pit of a Metro Station GAO Bo1 LI Fangming2,3 ZHU Liming2 LIU Xuezhu4 In this paper the influence of the deep foundation pit excavation in deep soft soil layer on adjacent two rows of houses was studied, and the protective effect of the combined consolidation method of the isolation pile and anchor rod static pressure pile was discussed. Through a two-dimensional plane strain finite element analysis model,a simulation of isolation pile diameter, pile length and pile position on the settlement of the first row of housing was conducted, and the reasonable design parameters of pile length, pile diameter and pile position were presented. Furthermore simulated calculations of housing settlements were conducted regarding the four cases of having no isolation pile and anchor bolt static pressure pile, having isolation pile but without anchor bolt static pressure pile, having no isolation pile but with anchor bolt static pressure pile, and having isolation pile and anchor bolt static pressure pile, and finally the effect of deep foundation pit excavation of the metro station on the safety of adjacent housing was predicted reasonably. 2018 Vol. 55 (6): 117-123 [Abstract] ( 773 ) [HTML 1KB] [ PDF 2358KB] ( 1843 ) 124 Modification of Subfilter-scale Model in Large Eddy Simulation for Flow Field in Highway Tunnels JIN Sike1,2 JIN Jiali1 GONG Yanfeng2,3 The complexity of highway tunnel flow field has brought a lot of difficulties to numerical calculation, the problem of excessive dissipation of small-size eddy exists in both the dynamic eddy viscosity model and dynamic mixed model. The main reason is that there is strong shear stress for the turbulence near the wall of highway tunnels,causing large dissipation of small size eddy, but the simulated dissipation in the model is not sufficient to balance it.A study on turbulent energy cascade mechanism shows that the large-scale motion is not sensitive to the details of small-scale motion in the turbulent flow field, and as long as the SFS model provides appropriate kinetic energy dis-sipation rate, the roughly correct statistical law can be obtained from the simulation results of large scale motion.Based on the above ideas, an eddy viscosity coefficient model for highway tunnel flow field is proposed. The model can generate an appropriate kinetic energy dissipation rate so as to balance the energy dissipation of SFS motion. Its accuracy is verified and the effect is ideal through the comparison of the measured data of model and DNS calculation results. 2018 Vol. 55 (6): 124-130 [Abstract] ( 820 ) [HTML 1KB] [ PDF 2282KB] ( 1456 ) 131 Influence of Light Distribution and Installation Style of Luminaires on Power Consumption and Lighting Effect of Tunnel Lighting YANG Chao LI Min XIAO Yu XU Yihang Light distribution (LD) and installation style of luminaires affect the utilization factor (UF) of luminaires,and the UF affects the luminaire power and road pavement illuminance and further the power consumption of illuminating system and the luminous effect of road pavement. An UF model of tunnel lighting was established based on the luminaire LD data and installation parameters, in which four LD styles were adopted. For each LD the parameters optimization and simulation were conducted regarding four installation styles, e.g. central style, offset-of-vault style, symmetric style and staggered style. The energy-saving and the lighting effects of each LD and luminaire installation style at the tunnel middle zone were studied. The results show that symmetric luminaire installation is the most energy-saving style and has the best lighting effect than the other three luminaire installation styles; the lighting effect of central luminaire installation is the second best; staggered luminaire installation is the most energy-intensive style and has the worst lighting effect except for some special-shaped LD; waterdrop-shaped LD is the most suitable one along transverse direction of tunnel and applicable to the central, offset-of-vault and symmetric luminaire instal?lation styles; symmetric butterfly-shaped LD is the most suitable one along longitudinal direction of tunnel and applicable to the central, offset-of-vault, staggered and symmetric luminaire installation styles; with waterdrop-shaped LD along transverse direction and symmetric butterfly-shaped LD along longitudinal direction, they are suitable for the above four luminaire installation styles, and have better energy-saving and lighting effect; as for the LD with symmetric and oblique curve, it′s better for the profile of oblique luminaire distribution to be comply with that along tunnel transverse direction, and it is suitable for the symmetric and offset-of-vault luminaire installation styles. 2018 Vol. 55 (6): 131-138 [Abstract] ( 815 ) [HTML 1KB] [ PDF 2044KB] ( 1436 ) 139 Effect of Explosion in a Gas Pipeline Compartment of a Utility Tunnel on Neighboring Metro Tunnels ZHAO Yongjian1 GONG Yi2 DING Yong2 DONG Xuehua2 In this paper the numerical simulation analysis of the effect of explosion in the gas pipeline compartment of a utility tunnel on neighboring metro tunnels was conducted using the software AUTODYN. The results show that the TNT equivalent in a fireproof partition with length of 200 m is 41.6 kg when the gas concentration in the gas pipeline compartment reaches 10%; the blast wave has much effect on the crown and arch waist of the round metro tunnel and it′s necessary to take some protective measures in both areas; when the surrounding soil is sand, the utility tunnel is above the round metro tunnel and their alignments are in the same direction, the greater the vertical spacing between the utility tunnel and the metro tunnel, the smaller the effect of the blast wave on the metro tunnel;when the vertical spacing is 7.2 m, the maximum dynamic tensile stress is 1.86 MPa (including the static stress value of 1 MPa in the tunnel segment) and it is slightly smaller than the designed tensile strength of metro tunnel (about1.89 MPa). The maximum vibration velocity and the maximum displacement meet the structural stability requirements, so it is suggested the vertical spacing between the utility tunnel and metro tunnel shall not be less than 7.2 m. 2018 Vol. 55 (6): 139-143 [Abstract] ( 872 ) [HTML 1KB] [ PDF 2055KB] ( 1680 ) 144 Anti-cracking Design for a Tunnel on the Lintong Line of Xi′an Metro Crossing Ground Fissures and Fault Zones HUANG Qiangbing1,2 GUO Rui3 ZHANG Ning1 MENG Zhengjiang1,2 Based on the Lintong line of Xi′an metro crossing ground fissures and fault zones, the characteristics of ground fissure and active fault zone intersecting with the Lintong line were analyzed, the predicted and designed maximum vertical displacements of ground fissures in the design life of 100 years were determined. Considering the three-dimensional displacement relationship of the segmented metro tunnel, the three-dimensional reserved displacements of the anti-cracking structure were calculated. In view of an analysis on seismic risk near field and at field as well as the two movement patterns of active fault zone, i.e. creep slip and stick slip, the maximum surface vertical displacements induced by the activity of Lishan fault were estimated by empirical formula, and the reserved displacements of 500 mm were suggested. 2018 Vol. 55 (6): 144-151 [Abstract] ( 840 ) [HTML 1KB] [ PDF 2585KB] ( 1728 ) 152 Full-scale Test on Ultimate Bearing Capacity of Tunnel Segment Lining with Staggered Joints ZHU Yaohong1 ZHANG Yumeng2 XIA Yangyuyu2 DONG Zibo3 LIU Xian2 Aiming at the serious effect of soil and water loss on tunnel operation and safety, full-scale quasi-static loading tests were conducted regarding the ultimate bearing capacity of staggered erected tunnel linings in unloading situation. The design of tested lining and loading schemes were introduced. The test results, including the evolution of deformation, segment crack, joint opening and bolt stress, were presented. The bearing capacity and failure mechanism of tested linings were discussed and analyzed. It shows load-displacement curve is of elastic-plastic form and the tendency of load-displacement curve is linearly rising; strength failure of circumferential joint occurs and the interaction between segments decreases, leading to decrease of integral rigidity; shearing failure of concaveconvex connector of circumferential segment joint, compression induced concrete failure of longitudinal joint and bending failure of the segment finally cause stability loss of the tunnel structure. 2018 Vol. 55 (6): 152-162 [Abstract] ( 826 ) [HTML 1KB] [ PDF 4728KB] ( 1440 ) 163 Model Test on Mechanism of Shear Resistance Borne by Concrete Shear Key and Friction of Element Joint of the Immersed Tunnel CHEN Fuqiang1,2 TIAN Wei1,2 ZHANG Yongtao1,2 ZHAI Shihong1,2 By scale model tests, it proves the mechanism mode of shear resistance borne by friction of contact area and concrete shear key in different contact stress states and cushion thicknesses of shear key. The results show that friction plays a significant role on shear resistance of element joint. 2018 Vol. 55 (6): 163-169 [Abstract] ( 882 ) [HTML 1KB] [ PDF 4083KB] ( 1841 ) 170 Experimental Study on Health Detection of Operating Metro Tunnels with Vehicle-mounted GPR SU Guofeng1,3 ZAN Yuewen1,2 SUN Wenlong1 CAI Wenbo1 HU Qihua1 LIU Xiangkui4 The vehicle-mounted GPR technique, a non-contact and long-distance detection method with air-cou? pled antennas, is a fast nondestructive detecting technique in the field of structural health safety assessment of tunnels and underground engineering, which has changed the traditional measurement method of hand-held GPR antenna closely attached to the tunnel lining. This paper describes the detecting conditions and working principles of this technique used in health assessment of metro tunnels, and evaluates the feasibility of vehicle-mounted GPR to detect the metro tunnel in the basis of analyzing the test results. The experimental results show that this technique could detect the metro tunnel at normal operating speed within the vehicle gauge, providing a new method for the maintenance and safety inspection of operating metro tunnels. 2018 Vol. 55 (6): 170-175 [Abstract] ( 845 ) [HTML 1KB] [ PDF 4587KB] ( 1664 ) 176 Application of Vertical Freezing Technique in the Deep-buried Mountain Railway Tunnel QI Weihua1 LI Guoliang1 ZHAO Luxue1 ZHANG Quanliang2 MA Qiang2 The strata of Chengershan tunnel is mainly consist of the slightly cemented tertiary sandstone, the tun? nel body passes through F2 fault core zone. Geological disasters of mud outburst, sand gushing and extrusion of work face occurred several times during tunnel construction, so the risks are very high. In view of the core zone of F2 fault with high pressure and abundant water, a variety of construction schemes were compared and analyzed in terms of technology, feasibility and safety, and vertical freezing technique was used for stratum reinforcement in the railway tunnel for the first time, furthermore the freezing scheme and tunnel support measures were studied, providing reference and guidance for similar tunnel construction. 2018 Vol. 55 (6): 176-182 [Abstract] ( 955 ) [HTML 1KB] [ PDF 3884KB] ( 1948 ) 183 Key Issues in Raise Boring of Super-deep Vertical Shafts of CCS Hydropower Station in Ecuador YANG Jihua WEI Bing QI Sanhong GUO Weixin The CCS Hydropower Station in Ecuador is a water diversion type power station, in which two superdeep vertical shafts with depth of 537.9 m are arranged. After comparison of alternative options, a new type of 1088DC RHINO raise boring machine was chosen to construct the vertical shafts. The construction process with the raise boring machine is divided into 3 stages, i.e. pilot hole construction by forward drilling, pilot shaft construction by reverse expanded excavation and shaft construction by manual expanded excavation. In view of the problems of buried drill bits and pilot hole deflection in the first stage, the problems of shaft collapse and cutter damage in the second stage, and the problems of collapse, water inflow and shaft blocking in the third stage, some preventive and treatment measures were proposed based on causes analysis, and good construction effect was achieved. The successful construction of super-deep vertical shafts at CCS hydropower station with raise boring method is significant to improve the construction level of deep shafts of domestic water conservancy and hydropower engineering, and the related research can provide a reference for the similar shaft engineering construction. 2018 Vol. 55 (6): 183-190 [Abstract] ( 918 ) [HTML 1KB] [ PDF 2047KB] ( 2252 ) 191 Study on Reinforcing Technology System for the Overlapped Running Shield Tunnels underneath the Track Group of High Speed Railway LI Wei1 REN Lizhi2 MENG Qingming2 GAO Hongbing3 FU Yanjun4 The large settlements of tracks will emerge due to multiple disturbances in the construction of over? lapped shield tunnels, which affects the running safety of trains. Based on the overlapped Sungang station—Honghu station shield running tunnels of Shenzhen Metro line 7 passing underneath 26 tracks of high speed railways, a reinforcement technology system consisting of“track support + subgrade reinforcement + interlayer soil consolidation +internal support of the lower tunnel”was developed. The settlements of tracks were mainly monitored automatically with manual monitoring as an auxiliary one. The results show that the maximum settlement of main track caused by constructing overlapped shield tunnels is -5.9 mm which is less than the control value of 10 mm, ensuring the operation safety and verifying the reliability and practicability of the reinforcement technology system. 2018 Vol. 55 (6): 191-196 [Abstract] ( 858 ) [HTML 1KB] [ PDF 2055KB] ( 2179 ) 197 Construction Techniques for the Small-radius Curved Shield Tunnels in Water-rich Fractured Stratum with High Pressure ZHANG Mingju1 ZHANG Zhenbo1 CHEN Feng2 A variety of construction problems, such as bad cutting effects of cutters, unreasonable boring parame? ters and blowout, are often encountered during shield tunnelling under unfavorable geological conditions. Aimed at these construction difficulties of high pressure, abundant underground water, fractured rock stratum, long distance and small-radius curves of Fuzhou metro, the mechanical behaviors of cutting tools were analyzed through theoretical calculations of cutter cutting force, then the reasonable cutter configuration, tunneling parameters and the proper time for cutter replacement were presented. Some measures, such as screw conveyor renovation, mucking control and lowering of groundwater, were adopted for controlling blowout based on practice. The stability of excavation face was analyzed by numerical simulation, and the measures for shield boring and posture control in the long distance and small radius curved tunnels were summarized. The conclusions are as follows: 1) when shield machine is driven in fractured stratum, the effect of lateral impact force produced by spalling rock on cutter will be very large and reinforcement is needed for cutter; 2) cutter replacement should be taken at proper time based on muck samples in conditions of increasing of total shield thrust by 4 000-7 000 kN, cutter torque by 1 000-1 500 kN·m and driving speed smaller than 10 mm/min; 3) adopting screw conveyor device with innovative anti-blowout devices and control measures for ground precipitation and mucking, it controls blowout effectively; 4) the maximum axis offset and the height offset of segment meet the requirements of shield construction specifications during shield construction of long distance small-radius curved tunnel. 2018 Vol. 55 (6): 197-203 [Abstract] ( 858 ) [HTML 1KB] [ PDF 2019KB] ( 1993 ) 204 Analysis and Research on the Tunnelling Technology of Compound EPB Shield Machine in High-strength Hard Rocks ZHOU Zhihui It′s really challenging for shield driving when hard rock partially intrudes into the excavation section of metro tunnels. Abnormal cutter wear is excessive during shield excavation in hard rock and comprehensive performance of excavation system decreases greatly, resulting in abnormal advancing parameter, small penetration rate and low advance rate. Taking Shenzhen Metro line 9 project as the background, the main difficulties encountered for the compound EPB shield during driving in high-strength granite and the reasons were analyzed, the corresponding countermeasures were presented. EPB shield drove through the hard rock section safely and smoothly attributed to reasonable cutter configuration, in-time cutter replacement and proper advancing parameters. 2018 Vol. 55 (6): 204-209 [Abstract] ( 926 ) [HTML 1KB] [ PDF 2822KB] ( 1955 ) 210 A Study of Prevention Techniques for Tunnel Lining Defects GONG Chengming1 LUO Yongjun2 ZHANG Jun2 Defects of tunnel lining, such as inadequate thickness, voids, cracks, rock falling and water leakage etc., endanger the safety of railway tunnel operation. Based on the site construction, an analysis of the reasons for lining defects was conducted; technical measures against lining defects were proposed and tests were carried out at site. The results show that these measures are reliable and effective, and the purposes of prevention and treatment are realized. 2018 Vol. 55 (6): 210-216 [Abstract] ( 831 ) [HTML 1KB] [ PDF 2850KB] ( 2298 ) 217 Flexible Overlap Technology for the Lining Trolley of Single-track Railway Tunnels LI Shu1 GUAN Depeng2 Falling-off of rock piece at tunnel arch and invert heave are the main potential safety problems affecting normal operation of the railway tunnel. The reasons causing falling-off of rock piece include squeezing by lining trolley at construction joint, concrete cutting by cantilever end of water stop at construction joint, construction cold joint at arch, concrete quality deficiency and so on. To eliminate the falling-off of rock piece at tunnel arch caused by rigid overlap, modification of lining trolley and the flexible overlap technique combining tray with rubber gasket were adopted during the construction of Nuwashan tunnel on China-Laos railway, and the potential quality problem due to rigid overlap at construction joint of tunnel lining were effectively solved. 2018 Vol. 55 (6): 217-221 [Abstract] ( 816 ) [HTML 1KB] [ PDF 3236KB] ( 1824 )

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