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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2021 Vol.58 Issue.2 Published 2021-04-25 1 Discussion on the Technological Development of Loess Tunnelling in the Future LEI Shengxiang1 WANG Fei2 YU Jie2 SHAO Shengjun3 LIANG Qingguo4 Loess is a special kind of soil with very unique characteristics in China. Its vertical joints are developed. When it meets water it is easy to soften, while its physical and mechanical properties could decline sharply, and so it has remarkable engineering characteristics. The depth of a loess tunnel is generally shallow with obvious scale effect.During construction, it is prone to various issues such as collapse, surface cracking, lining cracking, substrate settlement, loess slope deformation, and loess sinking, etc. In recent years, relying on the construction of the loess tunnels of high-speed railways such as the Zhengzhou-Xi′ an high-speed railway, the Datong-Xi′ an high-speed railway and the Baoji-Xi′an high-speed railway, as well as the loess tunnels of metro projects in Xi′an, Zhengzhou, Luoyang and Lanzhou, a series of scientific researches have been carried out, which have obtained rich research results, providing good guidance to the engineering practice. With the continuous progress of construction technology and equipment level as well as the implementation of various tunnel projects in loess areas, this paper summarizes the state of the art in terms of the basic theory, survey and design, construction, operation and maintenance of loess tun? nels. With consideration to the actual problems arising in the current engineering construction, it puts forward some new technologies, new trends and new ideas pending for further research and breakthrough, which could provide a reference for the continuous development of loess tunnel construction technology in the future. 2021 Vol. 58 (2): 1-7 [Abstract] ( 1223 ) [HTML 1KB] [ PDF 3270KB] ( 3473 ) 8 On the Problem of“Geologic Uncertainty”in Tunnelling and Its Solutions HE Faliang For a long time, there is a common phenomenon that the geological disaster accidents occurred in the deeply-buried tunnels with complicated geological conditions are unjustly attributed to the geology, with the risk cause summarized as“geologic uncertainty”. On the basis of discussing the definition of uncertainty and its classification, this paper analyzes the cause of“geologic uncertainty”, summarizes and sets forth the types of“geologic uncertainty”and the solutions to the“geologic uncertainty”in tunnel construction. 2021 Vol. 58 (2): 8-13 [Abstract] ( 608 ) [HTML 1KB] [ PDF 2711KB] ( 1189 ) 14 On Development Law of Karst Water and Prediction of Water Inflow in a Tunnel in Southwest China ZHANG Junfeng1 LI Qiang2 SHI Yongyue2 WU Lei2 Karst groundwater is a key hydrogeological problem in tunnelling. Based on the surface and borehole survey on both sides of a tunnel on Chongqing-Kunming high-speed railway, the measurement and sampling at key geological and hydrological points are carried out, and the water flows of main springs, karst caves and rivers in the studied area are rechecked. In combination with the results of water quality analysis and isotope analysis, the distribution of soluble rocks and karst development law in the tunnel area are identified, the characteristics of occurrence,supply, runoff and discharge of karst water are analyzed, and the hydraulic connections among aquifers as well as between aquifer and the surface water are clarified. The potential concentrated water burst sections, water inflow volumes and corresponding risk levels are classified according to the lithology and structure. The tunnel area is divided into one first-level karst water system and four second-level subsystems, and the water burst risk is classified into four grades. The pure soluble horizontal runoff zone of the tunnel is a high-risk section of karst water inrush.The study results are of great significance in guiding the design, construction and operation of tunnel projects. 2021 Vol. 58 (2): 14-21 [Abstract] ( 634 ) [HTML 1KB] [ PDF 4507KB] ( 1504 ) 22 Study on Water Inflow Prediction Technology for Guanshan Tunnel on Tianshui-Pingliang Railway Zhou Wenjun Water inflow disasters usually occur in the construction of super-long tunnels in water-rich areas. Therefore, accurate prediction of water inflow in the tunnel can give a scientific guidance for design and construction of the tunnels. New Guanshan tunnel is located in the Guanshan fold belt, where groundwater circulation is powerful as well as rock joints and fissures are developed, having a greater impact on the safety of tunnel construction.In this paper, hydrogeological conditions of Guanshan tunnel are analyzed and different water inflow calculation methods are adopted to predict the water inflow in each studied section of the tunnel. It is found from the comparative analysis that the prediction result by the underground runoff modulus method is more practical. Meanwhile,FLAC3D software is used to simulate the water inflow in each section of Guanshan tunnel, and the groundwater level is inversely analyzed to obtain a groundwater level consistent with the actual situation. Then, according to the parameters obtained from the inversion, a three-dimensional numerical simulation is performed to predict the water inflow during the construction of Guanshan Tunnel, and the obtained water inflow could be used as a reference for the actual situation 2021 Vol. 58 (2): 22-30 [Abstract] ( 748 ) [HTML 1KB] [ PDF 2642KB] ( 1505 ) 31 Research on Full-Life-Cycle Inspection and Monitoring System of Railway Tunnels XU Xueliang1,2 MA Weibin1,2 CAI Degou1,2 AN Zheli1,2 CHAI Jinfei1,2 Inspection and monitoring are important means of controlling the construction quality of railway tunnels and ensuring its safe operation. With the implementation of the railway network planning and the increasement of numbers of railway tunnels in operation, China has entered a peak period of railway tunnel maintenance and repair.Nevertheless, contrary to the vigorous development of railway tunnelling, some problems in terms of tunnel inspection and monitoring are existed in China, such as the incomplete regulation and regime, the lack of technical standards, the low inspection efficiency, and the monotone technical means, etc. Based on the comprehensive investigation of the tunnel inspection regulations and regimes of foreign developed countries and other domestic industries,this paper proposes a set of whole-life-cycle inspection and monitoring system of railway tunnels based on the digital tunnel as the management target, with consideration to the actual site conditions and operation and maintenance characteristics of railway tunnels. The system integrates tunnel structure safety inspection, real-time condition moni? toring, information acquisition and communication, and dynamic warning, which would provide technical support for railway tunnel operation and maintenance and ensure the quality and safety of railway tunnels. 2021 Vol. 58 (2): 31-40 [Abstract] ( 684 ) [HTML 1KB] [ PDF 4651KB] ( 2277 ) 41 Development of a Real-time Monitoring System of Cutterhead Conditions in Shield Tunnelling GONG Qiuming1 WANG Qinghuan1 WANG Dujuan2 QIU Haifeng3 WU Fan During the shield tunnelling, the cutterhead is in a black box state because the chamber behind the cut? terhead is pressurized. In order to monitor the working state of the disk cutters and cutterhead in real time, a realtime monitoring system of cutterhead conditions in shield tunnelling is developed. The system consists of three subsystems, namely the sensor subsystem, control and data transmission subsystem, algorithm and display subsystem.The sensor subsystem integrates the self-made disk cutter wear sensor, disk cutter rotation speed sensor, temperature sensor, data acquisition module and power supply unit. The integrated sensors are mounted in the disk cutter housings on the cutterhead to monitor the disc cutter wear and rotation speed and cutterhead temperature in real time. The collected data is transmitted to the central end through wire or wireless modes, and then transmitted to the upper computer by wire. The software of the upper computer integrates the shield design parameters, stratum parameters, shield driving parameters and sensor monitoring parameters, by which it can display the parameters monitored by these sensors in real time, comprehensively determine the working condition of the cutterhead and predict the service life of the disc cutters. Through laboratory testing and factory testing, this system is proven to meet the design requirements and can be used for monitoring the working state of shield cutterhead. 2021 Vol. 58 (2): 41-50 [Abstract] ( 662 ) [HTML 1KB] [ PDF 5362KB] ( 1670 ) 51 Study on Practical Application and Adaptability of the Roadheader in Transportation Tunnelling HUANG Jifu XIAO Gongyi The roadheader has been more and more used in the transportation tunnelling, but there are still many questions regarding its construction efficiency and adaptability in tunnels with different section sizes, geological conditions, etc. Accordingly, in combination with related project cases, this paper analyzes the construction efficiency and energy consumption issues in the construction of metro and railway tunnels with different section sizes and different geological conditions using the roadheader, comprehensively compares and analyzes its main performances and adaptability, and puts forward suggestions regarding the roadheader application scope, type selection, main operating performance and other aspects. 2021 Vol. 58 (2): 51-62 [Abstract] ( 760 ) [HTML 1KB] [ PDF 3550KB] ( 1854 ) 63 Study on Construction Risk Assessment of Tunnel Reconstruction and Expansion Works WANG Chunhe1,2 ZHU Fuqiang3 LUO Xing4 ZHANG Chuankui1,2 TIAN Junling3 LI Hepeng2 GUO Yifei4 To study the construction risks in the in-situ reconstruction and expansion of existing tunnels, by taking the Heiyu tunnel reconstruction and expansion project in Zichuan District, Zibo, Shandong Province as an example,an overall construction safety risk assessment table for tunnel reconstruction and expansion is established, the overall risk is evaluated as a very high risk with Ⅳ level. By conducting a general survey of hazard sources using the combined checklist method and expert investigation method, six major hazard sources are identified, and a special assessment of major risks is conducted. Taking the risk of collapse as an example, and in combination with the construction difficulty and supporting method of the tunnel reconstruction and expansion works, the index system method is used to assess the risk sources of the collapse, taking multiple factors into consideration such as advanced pipe-roof support, reinforcement of the existing tunnel portal, surrounding rock classification at the intersection of old and new tunnels, and support method at the intersection of old and new tunnels. Besides, risk mitigation measures in relation to supporting, blasting, reinforcement and other construction measures are developed to prevent tunnel collapse accidents. 2021 Vol. 58 (2): 63-70 [Abstract] ( 800 ) [HTML 1KB] [ PDF 2249KB] ( 1695 ) 71 Research on Safe Thickness of Overlying Rock Layer above Subway Tunnels in Upper-soft and Lower-hard Stratum ZHANG Ziguang1 CAO Guangyong1,2 LI Jianli3 ZHAI Chaojiao1,2 The thickness of the overlying rock above the vault of a tunnel in the upper-soft lower-hard soil-rock composite stratum plays a key role in maintaining the self-stability of the surrounding rock. However, there has not been a unified understanding or standard on the safe thickness of the overlying rock of tunnels and its general laws.Based on this, this paper first investigates the safe thickness of the overlying rock of metro tunnels with different thicknesses of weak stratum Hs and excavation spans D through the finite element strength reduction method, obtains the mathematical fitting equation between Hrcv , the critical safe thickness of the overlying rock, and Hs, the thickness of weak stratum in metro tunnelling, and draws the "Hrcv - Hs - D" three-dimensional spatial distribution map of the critical safe thickness of the overlying rock, the thickness of weak stratum and the excavation span. Then,through the statistical analysis of the monitoring data during the construction process of Qingdao metro tunnels, it is verified that the self-stability of the tunnel surrounding rock and the degree of its influence on the surrounding environment are positive correlated with the safe thickness of the overlying rock. 2021 Vol. 58 (2): 71-77 [Abstract] ( 827 ) [HTML 1KB] [ PDF 2154KB] ( 1042 ) 78 Prediction of Tunnel Limit Displacement Based on DE-GP Collaborative Optimization Algorithm LI Xingsheng In order to overcome the problems (e.g. more parameters, excessive calculation amount) of the numerical calculation method in the process of solving the limit displacement of the tunnel, the Gaussian Process (GP) is introduced into the calculation of the limit displacement of the tunnel. Meanwhile, the Differential Evolution (DE) algorithm is adopted instead of the conjugate gradient method to search for the optimal GP hyperparameters during the training process so as to overcome the disadvantages that the conjugate gradient method is excessively dependent on initial values, difficult to determine iterations and easy to fall into local optimization, finally a limit displacement prediction method based on the DE-GP (Differential Evolution-Gaussian Process) collaborative optimization algorithm is presented. This prediction method greatly simplifies the solution process of the limit displacement while improving the generalization performance of the Gaussian Process with a single kernel function. Then, the limit displacement of a standard two-lane highway tunnel is calculated and the results show that the DE-GP collaborative optimization algorithm can significantly improve generalization performance compared with single GP and LS-SVM algorithm. The prediction results of the limit displacement are in good agreement with the calculated values and the calculation efficiency is significantly improved, which provides a new way for the solution of the limit displacement. 2021 Vol. 58 (2): 78-85 [Abstract] ( 570 ) [HTML 1KB] [ PDF 2245KB] ( 1175 ) 86 Analysis on Ground Surface Heaving ahead of Cutting Face Caused by Largesection Rectangular Pipe Jacking in Soft Soil Layer WU Bo1,2 PENG Yiyong1,2 MENG Guowang1,2 PU Songquan3 The large ground surface heaving in front of the cutting face during the pipe jacking is studied on the ba? sis of a large-section rectangular jacking pipe works at the entrance/exit of a subway station in Ningbo. The monitored data of ground surface deformation in the whole pipe jacking process are analyzed in combination with the jacking situation on the site. Moreover, PLAXIS finite element software is used to simulate pipe jacking under different jacking forces and without soil reinforcement, and the simulated results are compared and analyzed with the monitored data. The analysis results show that the large ground surface heaving can be generated due to excessive jacking force, and vice versa; the jet grouting piles used for reinforcing the entrances/exits area adjacent to the structure have no desirable effect, and it could cause the ground surface heaving at the beginning of jacking. The ground surface heaves rapidly when the pipe jacking and extruding in the soft soil layer, but subsides slowly after the jacking face passing. So, special attention should be paid during the construction. 2021 Vol. 58 (2): 86-92 [Abstract] ( 671 ) [HTML 1KB] [ PDF 3690KB] ( 1302 ) 93 Research on Reasonable Combination Forms and Mechanical Deformation Characteristics of Double-layer Superimposed Lining in Deep-buried Tunnels under the Action of Far-field Hydrostatic Pressure GAO Xin WANG Wenjuan In regards to the threats to traditional composite lining structure of deep-buried long tunnels caused by groundwater with high water head, this paper studies a double-layer superimposed lining scheme, which adopts the design concept of "dividing the lining structure into two parts and installing two water-proof layers" , to not only overcome the construction difficulties of mass concrete but also address the leakage issue of secondary lining structure. This paper takes the sea-crossing tunnel project of Qingdao metro line 1 as the engineering basis and analyzes the reasonable combination forms and mechanical deformation characteristics of the double-layer superimposed lining through the finite element calculation software ANSYS. The results show that the internal force distribution of the superimposed lining is related to the structural stiffness ratio of the inner and outer lining layers; the greater the stiffness ratio is, the greater the internal force will be, and when the structural stiffness ratio of the inner and outer lining layers is 0.716, the optimal combination of the superimposed lining thickness is tA=0.95 m and tB=0.85 m; the risk ranking of each control section of the tunnel structure is inverted arch > arch foot > vault; under the action of ex? ternal water pressure on the superimposed lining, the deformation of inner and outer lining layers is coordinated with each other, while the deformation of the inverted arch structure is more sensitive to the stiffness ratio and the external water pressure value than that of the vault and sidewalls; the combination form of the superimposed lining is controlled by the structural load-bearing capacity rather than by the deformation; the structural safety of the optimal superimposed lining combination is also controlled by the bearing capacity when the external water pressure is lower than 1.2 MPa. 2021 Vol. 58 (2): 93-102 [Abstract] ( 671 ) [HTML 1KB] [ PDF 5260KB] ( 1412 ) 103 Study on Deformation Mechanism of the Underlying Tunnel Caused by Excavation of the Deep Foundation Pit in Sandy Stratum FAN Yanbo1, 2 CHEN Li3 SHI Jiangwei1, 2 DING Chu1, 2 ZHANG Xian1, 2 he stress release caused by excavation of a deep foundation pit may inevitably cause additional stress and deformation of the adjacent tunnel. In this paper, a three-dimensional finite element numerical analysis is performed to study the influence of the excavation size of the deep foundation pit and the stiffness of segment joint on three-dimensional deformation of the underlying tunnel. Then, the geotechnical centrifugal model test is used to verify the rationality of the finite element calculation model and relevant results. Below the centerline of the foundation pit, the uplift and lateral bending strain of the tunnel increase along with the increase of the excavation length of the foundation pit. When the excavation length of the foundation pit is 9 times of its excavation depth, the uplift and transverse bending strain of the tunnel reach the peak value while the longitudinal bending strain of the tunnel is almost close to zero. When the excavation length of the foundation pit is more than 9 times of the excavation depth, the foundation pit-soil-tunnel interaction could be simplified as a plane strain issue. If the three-dimensional effect of the short foundation pit is not considered, the plane strain simplification of the foundation pit-soil-tunnel would seriously lead to overestimate of the tunnel uplift and lateral bending strain. Along with the increase of the joint stiffness, the tunnel uplift gradually decreases, while the transverse and longitudinal bending strains of the tunnel increase. Therefore, if a discontinuous tunnel with joints is assumed as a continuous structure, the tunnel uplift might be greatly underestimated, while the bending strain might be largely overestimated. 2021 Vol. 58 (2): 103-110 [Abstract] ( 694 ) [HTML 1KB] [ PDF 4127KB] ( 867 ) 111 Analysis on Pre-grouting Reinforcement Effect of Pipe Roofs for the Shallowburied Mined Tunnel in Soft Rocks YUE Hongwu1 MIAO Miao2 In order to study the pre-grouting reinforcement effect of the pipe roof support for the shallow-buried mined tunnel in broken soft rocks, taking a certain tunnel project as the background, the MIDAS/GTS finite element software is adopted to establish three excavation models: pipe roof support with pre-grouting, single pipe-roof support and no pre-support, and then numerical simulation analysis is carried out accordingly. The results show that taking the pipe-roof pre-grouting measures, a reinforcement zone could be formed above the tunnel vault, which can bear most loads of the surrounding rocks in the area to be excavated, improve the arching ability of the ground, effectively control the surface subsidence, vault subsidence and stress concentration, and reduce surface subsidence by 52.7%, vault subsidence by 58.9%, arch foot convergence by 61.4%, invert heave by 63.8% and vertical stress by 79.2%. The pipe-roof support can significantly bear the pressure of overlying rocks, effectively decrease the bending moment of the lining, prevent the shotcrete from cracking failure and reduce the tensile force of the anchor bolt during the soil layer deformation; moreover, compared with the pipe-roof pre-grouting support, the single pipe-roof support has the same significant effect on controlling the convergence of side walls and invert heaving of the tunnel.For a shallow-buried tunnel underneath the existing important pipelines in weak and broken rocks, the pipe-roof pre-grouting support method could be adopted to ensure safe and smooth progress of the project, providing a certain reference for similar projects. 2021 Vol. 58 (2): 111-117 [Abstract] ( 606 ) [HTML 1KB] [ PDF 3747KB] ( 913 ) 118 Comparison and Selection of Construction Methods for Changsha-Ganzhou High-speed Railway Tunnel Section Adjacent to the Runway of Huanghua Airport YANG Jian1,2 For the Changsha-Ganzhou High-speed Railway tunnel section adjacent to the runway of Huanghua Airport, strict surface settlement control is required during construction. In this paper, aiming at four common construction methods such as mined construction method, shield method, pipe-roof method and pipe jacking method,the calculation results of the stress of surrounding rock mass, the development of plastic zone and the surface settlement variation during the tunnel construction are compared and analyzed through numerical simulation analysis.The result shows that the surface settlement caused by the mined construction method is the largest with the value more than 2 cm, which has a great impact on the tunnel and surface buildings; regarding the shield method, the pipe roof method and the pipe jacking method, the excavation-induced settlement can be effectively controlled below 5mm, meeting the tunnel construction and airport operation safety requirements. Considering the factors such as cost and technical conditions, the pipe roof method is finally recommended for the construction of this tunnel section. 2021 Vol. 58 (2): 118-126 [Abstract] ( 579 ) [HTML 1KB] [ PDF 6160KB] ( 878 ) 127 Global Sensitivity Analysis on Parameters of the Prediction Model for Shield Vertical Attitude HU Changming1,2 LI Liang1 MEI Yuan1,2 YUAN Yili1 WANG Zhiyu1 The shield attitude deviation from the designed axis is a common construction problem. Determining sen? sitive factors that may influence the shield attitude is of great significance for the shield attitude control. To quantitatively analyze the sensitive factors that may influence the shield vertical attitude, a shield construction case in pebble ground with underlying expansive mudstone stratum in Chengdu is taken as the engineering background, and the support vector regression (SVR) algorithm is used for establishing a prediction model for the shield vertical attitude,with the tunnelling parameters, geological parameters, and geometric parameters as input variables, and the shield vertical attitude tendency as the output variable. On this basis, the Sobol′ sensitivity analysis method is used for quantitative analysis on the global sensitivity of the model parameters. The research results show that the model prediction results are in good agreement with the actual results, which proves the reliability of the SVR model in the shield attitude prediction; It is concluded that the thrust difference between the upper and lower jacks is the most sensitive factor, the first-order sensitivity of synchronous grouting is relatively higher, and the first-order sensitivity,coupling sensitivity, and total-order sensitivity of geological parameters and the geometric parameters are all higher. 2021 Vol. 58 (2): 127-134 [Abstract] ( 714 ) [HTML 1KB] [ PDF 2198KB] ( 1277 ) 135 Finite Element Study on Working Mechanism of Plugging Airbags in Tunnels under External Pressure CHEN Jing1 YAN Shuwang2 ZHONG Xiaokai3 In the process of construction and operation of tunnels, the groundwater leakage, flood burst and harmful gas diffusion and other disasters pose a threat to the life and property safety of people. A temporary“isolating and blocking wall”can be created in a very short time by inflatable airbags to control the dangerous sources within a certain range, thus avoiding the expansion of the disaster. The inflatable airbag is of membrane structure, and its stress and deformation characteristics under external pressure have direct impact on the plugging failure mode of the airbag. Theoretical analysis on deformation and failure modes of the airbag under external pressure is conducted, and the accuracy of the theoretical formula is verified by a visualization model test. In this paper, based on the membrane theory and cavity theory in ABAQUS finite element, the inflating process of airbags under the model test condition and the deformation process under external pressure are simulated, and the comparison with the theoretical analysis results and the experimental data is conducted. Also, the effect of coefficient of the friction between the air? bag and the tunnel wall on the airbag deformation is studied. The result shows that the simulation result obtained using such method is highly identical to the model test data and values derived from the theoretical formula. Moreover,it can overcome the limitations of the theoretical formula in calculating the shape of the airbag, the material characteristics, the friction coefficient of the tunnel wall, etc., and reflect the various characteristics of the plugging of airbag more comprehensively, with a wider applicability. 2021 Vol. 58 (2): 135-144 [Abstract] ( 712 ) [HTML 1KB] [ PDF 5301KB] ( 1151 ) 145 Research on Towing Issues of Immersed Tunnel Elements on Long-distance and Complex Route WU Jiancheng The construction window period of offshore immersed tunnel elements is short and the ocean environ? ment is complex and changeable. In order to ensure the safety and control of the tunnel elements during the towing process, it is necessary to study the motion response of the immersed tunnel elements under the action of the wind,waves and currents during the towing formation navigation, consider the yawing effect of the lateral deviation force generated by the wind, waves and currents on the tunnel element formation, and analyze the ability of the tugboat to correct the deviation of the tunnel element formation. Taking the floating of the tunnel elements of the lot S08 of the Shenzhen-Zhongshan sea-crossing project as an example, it introduces a numerical calculation method for the analysis of the squat of the tunnel elements during the towing process on long-distance and complex route through the calculation example of a certain tunnel element, and validates the calculation results through empirical formulas.Through the analysis of the motion response of the tunnel element, this paper proposes a deviation correction analysis procedure applicable for the towing process of the tunnel element and offers the corresponding control measures for related specific problems. 2021 Vol. 58 (2): 145-150 [Abstract] ( 665 ) [HTML 1KB] [ PDF 2934KB] ( 1181 ) 151 Study on Structural Design and Safety of Shed Tunnels in the Scenic Area of Changbai Mountains WEN Xu1 PEI Xiangjun1 PEI Zuan1 YANG Hailong1 CHEN Zhenlin1 ZHANG Yichen2 Geological disasters occur frequently in the south scenic area of Changbai Mountain, especially the dan? gerous rock masses on the upper part of the slope along the highway in the scenic area are well developed, which can lead to landslide and rockfall disasters, posing a threat to the safety of life and property of tourists. In order to ensure the smooth operation of the south scenic area of Changbai Mountain, it is planned to build a shed tunnel to protect the highway in the Grand Canyon section of Yalu River. The shed tunnel is designed in such a way that it has both the basic protection functions and the architectural characteristics in the Changbai Mountain area, so as to be integrated into the surrounding environment. Besides, the stability of the designed shed tunnel under the impact of dangerous rock mass is verified through the impact numerical simulation calculation, indicating that the design scheme of the shed tunnel is safe and feasible. 2021 Vol. 58 (2): 151-157 [Abstract] ( 748 ) [HTML 1KB] [ PDF 4349KB] ( 1376 ) 158 Study on Engineering Geological Survey of Qamchiq Tunnel on Angren-Pap Railway in Uzbekistan YUAN Zhenxiu JIA Xiangyu SUN Zhongke Located at the critical geological node for the Belt and Road Initiative, Qamchiq tunnel on Angren-Pap railway in Uzbekistan is the longest tunnel in Central Asia. The tunnel is located in the highly seismic area of IX degree, with very complicated geological conditions. In order to obtain accurate geological survey data to guide design and construction, the survey and design enterprise from China implements the Uzbekistan′ s national standards for the project, and formulates the technical standards and principles for survey, which is recognized by the two countries. On the basis of the full collection of the data on the studied area, a comprehensive survey method focusing on geological survey and mapping and combined with the geophysical exploration, drilling, in-situ test and laboratory test is established, the engineering geological and hydrogeological conditions of the tunnel are identified, and accurate geological data are obtained, thus guaranteeing the safe and smooth implementation of the project. 2021 Vol. 58 (2): 158-165 [Abstract] ( 625 ) [HTML 1KB] [ PDF 4656KB] ( 1258 ) 166 Study on Selection of the Intermediate Pile Foundation of Subway Stations with Cut and Cover Top-down Method CHEN Liang For the subway station constructed with cut and cover top-down method, the vertical supporting system used during the construction is composed of the foundation pit supporting structure, intermediate column and pile foundation under the column, and the stability of the vertical supporting system is the key to the success of the project. Since the intermediate pile foundation bears the roof casingsoil, the dead weight of the roof and the intermediate floor structure, the road vehicle load and the construction load, etc., the selection, bearing capacity and settlement calculations of the intermediate pile foundation should be carried out according to the engineering geological conditions, the layout of the column network, the type of intermediate column and the construction requirements. Taking Zhongnan Road Station of Wuhan Metro as an example, comparison among four schemes of the pile foundation under column for the vertical support system of the station with cut and cover top-down method is conducted in this paper. By analyzing the bearing capacity, settlement, construction period and economic requirements of the intermediate pile foundation, it is finally decided to use the scheme of screw-drilled under-reamed hydraulically cast-in-situ pile for construction. The pile test on the site, construction feedback, and deformation monitoring results show that the settlement of each pile top is no more than 3.7 mm and the ground settlement is 6.45 mm during construction after the technology of screw-drilled under-reamed hydraulically cast-in-situ pile is used, which can meet the settlement control requirements for pile body and surrounding buildings very well. Besides, with a lower cost and shortest construction period, the scheme of screw-drilled under-reamed hydraulically cast-in-situ pile is the best one for Zhongnan Road Station of Wuhan Metro. 2021 Vol. 58 (2): 166-173 [Abstract] ( 604 ) [HTML 1KB] [ PDF 2637KB] ( 772 ) 174 Study on Reasonable Construction Method for Tunnels in Contact Zone of Red Clay and Sandstone Interbedded with Mudstone YU Jie In view of the characteristics of upper-soft and lower-hard rocks with poor self-stability in the contact zone between red clay and sandstone interbedded with mudstone, this paper, by carrying out field investigation and analysis, clarifies the construction principles and optimizes the construction methods and support parameters through the numerical simulation calculation in combination with actual conditions on the site. The field application results show that the position of the lithological interface has an obvious effect on the deformation and structural stress of the tunnel when construction in the contact zone of red clay and sandstone with mudstone, as the proportion of red clay in the excavation section increases, the displacement around the tunnel and the initial support stress increase significantly; after optimizing the construction method by adjusting the height of benches and cancelling the reserved core soil, the maximum deformation value does not exceed the allowable value, the maximum compressive stress of the initial support does not reach the material failure strength, and the stress concentration phenomenon of surrounding rocks is weakened, meeting the safe construction requirements; the advance rate is significantly increased, avoiding the problems such as rock falling and collapsing in the lithological interface. 2021 Vol. 58 (2): 174-181 [Abstract] ( 645 ) [HTML 1KB] [ PDF 3127KB] ( 743 ) 182 Study on Sources and Hazards of Crude Oil and Harmful Gases in Huangjialiang Tunnel on Xi′an-Chengdu Passenger Dedicated Line YU Hongping1 SU Peidong2 ZHAO Tianbiao3 CHEN Dejun1 XU Xueyuan1 DU Yuben1 The Huangjialiang tunnel on Xi′ an-Chengdu passenger dedicated line is located in the front structural belt of northern Longmenshan thrust, containing multiple sets of Cambrian-Triassic source rocks and oil-gas reservoirs, as well as multiple oil-bearing reservoirs, e.g. Tianjingshan and Kuangshanliang, so that the geological background for oil and gas generation is desirable. In this paper, the components of crude oil and harmful gases in the Huangjialiang tunnel are determined through the on-site inspection and indoor test. The results show that the crude oil mainly contains carbon element, followed by hydrogen element. Hazardous gases are mainly hydrocarbon gases,of which methane content is the most, and the non-hydrocarbon gases are mainly H2S, CO2 and N2. The determination of carbon isotope of oil and gas samples indicates that both crude oil and harmful gases come from the Lower Cambrian black mudstone. In combination with engineering situation of the tunnel, it could be seen that crude oil might pollute groundwater and soil vegetation and also corrode the supporting structure. When reaching a certain concentration, the harmful gas might explode and also threaten the life and safety of constructors. Therefore, in the actual construction process, appropriate treatment measures should be taken to reduce the impact of oil and gas on construction progress and safety. 2021 Vol. 58 (2): 182-187 [Abstract] ( 706 ) [HTML 1KB] [ PDF 2050KB] ( 1454 ) 188 Experimental Study on Dust Suppressing Agent for Hydraulic Blasting in Mountain Tunnels LAI Hongpeng1 ZHOU Donghui1,2 SONG Zhubing3 LIANG Yanlong3 The application of hydraulic blasting technology in tunnel engineering has reduced the blasting dust con? centration to a certain extent and improved the working environment. However, due to high surface tension of water and its poor wetting ability to dust, the actual dust-suppressing effect is not ideal. In order to solve the problem of poor dust-suppressing effect of hydraulic blasting, a certain amount of surfactant and inorganic salt are added to the water, according to the characteristics of tunnel blasting dust, to reduce the dust generated by blasting. With experimental indicators of surface tension and wetting height, the best surfactant, inorganic salt synergist and their concentrations are determined by comparative experiment. The results show that the dust suppressant composed of surfactants and inorganic salts could significantly improve the wetting ability of the solution to dust; the dust suppressant composed of rapid penetrant T, CAB-35 and sodium silicate (with mass fractions of 0.20%, 0.30% and 0.10%, respectively) has good surface activity and wettability. Therefore, the dust suppressant could effectively reduce the concentration of blasting dust to improve the construction environment thereby. 2021 Vol. 58 (2): 188-194 [Abstract] ( 581 ) [HTML 1KB] [ PDF 2402KB] ( 1193 ) 195 Performance Test and Engineering Application of Macro-polyolefin Fiber Reinforced Shotcrete Used as Single-shell Lining LI Deming1 WEN Shuyi1 ZHANG Jianwei2 YAN Jinxiu1 In order to study the applicability of the macro-polyolefin fiber reinforced shotcrete layer to permanent single-shell lining in tunnels, the mechanical mechanism of the macro-polyolefin fiber reinforcement in concrete is firstly analyzed based on the mechanics principle of synthetic fiber shotcrete structure, and then the mechanical property and durability of macro-polyolefin fiber reinforced shotcrete is tested in the laboratory. Besides, the monitoring and measurement results of the crown settlement, horizontal convergence and the ground surface settlement are analyzed based on the project case of Xizhen Station of Qingdao Metro, and the three dimensional numerical analysis is also conducted by the FLAC3D. The results show that the macro-polyolefin fiber reinforced shotcrete has a high compressive and tensile strength, good toughness and excellent durability, low rebound rate in spraying operation during the field implementation process. Therefore, it is an ideal support material for the permanent singleshell lining with good application value. 2021 Vol. 58 (2): 195-203 [Abstract] ( 680 ) [HTML 1KB] [ PDF 3207KB] ( 1419 ) 204 Deformation Control Method for Cross-steel Joints of the Diaphragm Wall in Super Deep Foundation Pits WU Jun1, 2 DENG Xifei3 Taking the construction of diaphragm walls in the super deep foundation pit group at East Railway Sta? tion of Hangzhou Metro Line 6 Phase II as the example, this paper summarizes and analyzes the types and causes of the deformation of the cross-steel joints of the diaphragm wall, and introduces the comprehensive deformation control method composed of adding diagonal bars to the steel plate joints, welded reinforcing the longitudinal steel plate joints and optimizing the backfill materials outside the steel plate joint. The effectiveness of the method is verified by the field practice, providing important reference value for the design and construction of steel reinforcement cages of similar diaphragm walls in the super deep foundation pits in China. 2021 Vol. 58 (2): 204-207 [Abstract] ( 632 ) [HTML 1KB] [ PDF 2851KB] ( 1321 ) 208 On Transfer Technology of D&B Construction Method and Shield Construction Method at the Interface of a Subsea Tunnel and Its Application DU Baoyi1 SONG Chaoye1 HE Weiguo1 LI Kai 2 As for the running tunnel section between Wuyuanwan station-Liuwudian station of Xiamen metro line 3, the construction method of " dismantling shield machine in the subsea and continually excavating the rest of section by the D&B method" is adopted. It is required to overcome such technical difficulties as shield disintegration in a confined space, long-distance single-line transportation, long-distance blind ventilation, protection of formed segments, waterproofing of joint structures, etc. The paper systematically expounds the transfer technology of various construction methods in Wuyuanwan station - Liuwudian station section and mainly introduces the solutions to the above construction difficulties. It has been proved in practice that this technology can greatly improve the construction progress under the premise of guaranteeing construction safety and structural function completeness, having reference significance for the subsea tunnel constructed by multiple combined methods. 2021 Vol. 58 (2): 208-213 [Abstract] ( 622 ) [HTML 1KB] [ PDF 4532KB] ( 1517 ) 214 Study on Engineering Characteristics of Tertiary Mudstone and Construction Technology of Inverted Arch ZHANG Xianwei1 HONG Kairong2 CHANG Xiang2 CHEN Hong1 To solve the problem of softening and strength decrease of tertiary mudstone due to groundwater conver? gence and excavation disturbance during the inverted arch construction of a tunnel, the laboratory test is carried out by field sampling. The results show that the uniaxial compressive strength of the tertiary mudstone in the natural state is negative correlated with the water content, the uniaxial compressive strength of the mudstone in the saturated state is obviously reduced with obvious softening effect, and the bearing capacity of the foundation after softening cannot meet the design requirements. In view of this, the water flows in different paths are classified and collected to reduce their deterioration effect on the surrounding rocks during the construction. The measures such as backfilling of the base with gravels and grouting reinforcement can solve the problems of seepage channel and surrounding rocks softening due to excavation disturbance of inverted arch, and the problem of insufficient bearing capacity of foundation is also effectively solved through the grouting reinforcement in the later period. Moreover, the indepen? dent vertical and horizontal drainage systems are added in the water-rich sections, so that the water accumulated in the base of the inverted arch can be drained in time when the pressure condition is met, thus avoiding the possible basement diseases caused by bedrock softening due to the effect of groundwater after operation. 2021 Vol. 58 (2): 214-219 [Abstract] ( 525 ) [HTML 1KB] [ PDF 2520KB] ( 806 ) 220 Comparison of Construction Schemes and Layout of Temporary Facilities for the Entrance/Exit Section of a Large-section Loess Tunnel on High and Steep Slope LI Dongshun When a tunnel is built in the gully and hilly area of the Loess Plateau, the portal is usually located on the loess steep wall in the halfway of the "V"-shaped gully. Due to great height difference, narrow portal site, uneasy accessing and difficult layout on the construction site, improper construction at the portal of a large-section loess tunnel may easily cause hazards and engineering accidents. Especially, the blind heading may cause collapse accidents very easily, for no large pipe roofs are installed form the outside of the tunnel and it is not easy to understand the buried depth conditions at the portal section. In order to ensure the construction safety of tunnel entrance/exit section, taking the entrance of the Lanshan tunnel on Baoji-Lanzhou passenger dedicated line as an example, four construction schemes are drawn up, namely excavating the tunnel entrance by backfilling portal site, excavating the tunnel entrance by building the temporary road, excavating the tunnel entrance by transverse adit and excavating the tunnel exit by three-bench method, as well as excavating the tunnel entrance by transverse adit and then excavating the tunnel ex? it by single-side drift method. The four schemes are analyzed and evaluated in terms of safety,environmental impact,construction period, cost, feasibility, etc. to select the best one, which is successfully applied in the entrance/exit construction of the Lanshan Tunnel. By installing a separate batching plant and a stairway to connect the living area on the half-mountain platform and the construction site at the bottom of the gully, the problems of narrow area and difficult layout on the construction site are solved. 2021 Vol. 58 (2): 220-227 [Abstract] ( 698 ) [HTML 1KB] [ PDF 4916KB] ( 870 ) 228 On Smooth Blasting Technology Assisted with Short Heading Cut Blasting for Tunnels with Small Sections and Long Steep Slopes ZHOU Han1 SUN Conghuang1 QU Yandong2 LI Dingzhong1 In industrial and mining engineering construction, due to the non-standard cross-section form and small cross-section size of mining tunnels, the working space is restricted and so results in a low degree of mechanized construction. Also, the existence of a long steep slope makes the tunnel easy to encounter blasting hole collapse and roof caving in the "drill and blasting" construction process, which could increase the construction cost and delay the construction period. To this end, based on the "drill and blasting" construction method principle, it proposes to adopt the cut blasting technology for the short heading on the tunnel face in combination with the design optimization of face blasting parameters and hole patterns. Furthermore, by means of the characteristic initiation system network composed of electric initiation, non-electric initiation and millisecond delay initiation, the full-section smooth blasting effect in one blasting process is realized for mining tunnels with a small section and long steep slope. The implementation of this method in the mining tunnel engineering of the Haitong cement project of Tibet Development and Investment Group Co., Ltd. could not only solve the problems of hole collapsing at the top of the tunnel and over-break due to excessive blasting angles, but also shorten the construction period by 120 days and save nearly RMB 8,962,000 in construction cost. 2021 Vol. 58 (2): 228-237 [Abstract] ( 544 ) [HTML 1KB] [ PDF 6248KB] ( 1280 )

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