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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2020 Vol.57 Issue.5 Published 2020-10-25 1 Hot-freeze Link Technology and Its Application in Snow Melting and Deicing of Tunnel Portal Section of Sichuan-Tibet Highway YAN Jian1,2 WEI Yanqing3 HE Chuan1 ZHOU Zihan1 GOU Hao1 In order to effectively utilize the geothermal water in the fault zone of Qinghai-Tibet plateau passed by Sichuan-Tibet highway, a heat-freeze link technology is developed to deal with snow melting and ice removal of the road surface within the scope of tunnel portal in cold area. Taking the Chola Shan tunnel as the engineering background, a geological investigation and field test are conducted to analyze the causes and characteristics of the geothermal water, the heating capacity of hot spring water is calculated based on the field tests of the temperature, velocity and flow of the hot spring water. Meanwhile, the heat demand for snow melting and deicing is calculated, and the feasibility of the hot-freeze link and its practical application effect are analyzed.The results show that: the accumulated time of snow over 10 cm thick on the road at tunnel entrance is 180 days and the time of dark ice is 210 days due to the effect of climate and topography of the Qinghai-Tibet Plateau. Controlled by the geological tectonism of the Qinghai-Tibet plateau and the northern fault zone, the theoretical calculation of the monthly heat supply capacity of the hot spring group in the tunnel site area of Chola Shan tunnel is 7.627×107-1.320×108 kJ. With Chapman model and heat-transfer model of fluid in heat exchange pipe of concrete, a calculation is conducted, and the monthly required heat supply capacity is 3.3×106 kJ and 8.25×107 kJ respectively in order to meet the requirements of snow melt and deicing of the 100 m long and 8 m wide road surface at the tunnel entrance; in the case of 60% utilization rate, hot spring water can still fully meet the needs of snow melting and deicing in the coldest month; hotfreeze link technology is developed by using hot spring water, hot spring water is rich in heat reserves and the height difference can ensure the flow and flow rate, thus pumping equipment is unnecessary and electric energy is saved,and the remained water can be reused due to high temperature. The field temperature test shows that the actual application effect of road snow melting and deicing is good. 2020 Vol. 57 (5): 1-9 [Abstract] ( 780 ) [HTML 1KB] [ PDF 3314KB] ( 1141 ) 10 Risk Evaluation of the Tunnel Passing through Active Fault Zone and Engineering Application YAN Xidong1 GAO Jun1 HAN Fei2 LI Zheng1 Construction of the tunnel passing through active fault zone often causes collapse and structure instabil? ity. The weight of each risk factor is determined by analyzing the risk factors of the highway tunnel passing through active fault zone, tunnel collapse and structure instability are analyzed by using attribute measure theory, and a risk evaluation model of the tunnel passing through active fault zone is established. The practical engineering application effect indicates the evaluation model can analyzes the tunnel risks quantitatively and provide a new method and approach for the similar projects. 2020 Vol. 57 (5): 10-22 [Abstract] ( 713 ) [HTML 1KB] [ PDF 2392KB] ( 1477 ) 23 On Power Performances of Tunnel Construction Machinery at High-altitude Area WANG Shuaishuai1,2 CHEN Guizhou2 GUO Chun2 BAI Yonghou3 In order to explore the influence of high-altitude and low-oxygen environment on the power performances of construction machinery, the construction transportation machinery is taken as the studied object, and the influence of altitude change on the power performances of construction machinery is studied by measuring the traction specific power. At the same time, traction specific power is used as a quantitative index of working efficiency of construction transportation machinery, and the regression model of altitude-working efficiency reduction coefficient of construction machinery and the regression model of altitude- consumption adjustment coefficient of construction machinery shift are established. The study results show that the higher the altitude is, the worse the power performance of machinery is. The traction specific power of construction machinery at 4 200 masl (above sea level) is 23% lower than that at 2 800 masl, and the working efficiency of machinery at 4 200 masl is 23% lower than that at 2 800masl. The higher the altitude is, the greater the consumption of machinery shift is, and the consumption of machinery shift at 4 200 masl is 24% higher than that at 2 800 masl. 2020 Vol. 57 (5): 23-29 [Abstract] ( 843 ) [HTML 1KB] [ PDF 2218KB] ( 1273 ) 30 Characteristics and Influencing Factors of Segment Cracking of LargeDiameter River-Crossing Shield Tunnelling in Composite Rock Strata GONG Chenjie1 YANG Junsheng1 FU Jinyang1, 2 The construction of shield tunnels in composite rock strata is vulnerable to cause segment cracking dis? eases, which has a serious effect on the operation and long-term safety. Based on a large-diameter river-crossing shield tunnel project, field investigations are carried out on the segment cracking during the construction phase. The typical cracking modes and distribution laws are summarized. Three typical rock strata, namely full-face highly weathered conglomerate, full-face middle weathered conglomerate, and their composite stratum are selected to explore the influence of seven key construction parameters on the segment cracking, such as rock condition and advancing speed etc. The results show that segment cracking diseases are composed of longitudinal joint cracking, circumferential joint cracking, corner cracking, bolt hole cracking, segment cracking and segment ring offset. The joint crack accounts for the largest proportion, mainly locating at the crown and its adjacent range of 45°. The joint cracking mechanism is the tensile/compressive failure induced by local stress concentration under uneven joint surface and eccentric jack/erector force. The rock strata conditions are negatively related to the segment cracking, the higher the rock grade, the fewer the cracks. The soft-hard composite stratum is more vulnerable to cause segment cracking,compared to homogeneous rock stratum. Higher advancing speed, larger thrust force, lower synchronous grouting volume and their data discreteness are primary influence factors of the occurrence of segment cracks. A proper and stable cutterhead torque value is beneficial to reduce the occurrence of segment cracks. 2020 Vol. 57 (5): 30-42 [Abstract] ( 835 ) [HTML 1KB] [ PDF 6994KB] ( 1273 ) 43 Research on Application of Random Source Model Based New Microtremor Survey Technology to Shield Tunnelling in Upper Soft and Lower Hard Strata ZHANG Xin Shield tunnelling in the upper soft and lower hard strata has always been accompanied by high construc? tion risks. In order to reduce the risk and cost, it is important to obtain accurate and comprehensive local geological information before tunnelling. However, as for the most of the conventional geological survey methods, it is difficult to provide the insight into regional stratigraphic information due to the several limitations. In this paper, it studies the random source model based microtremor survey method (MSM) especially in terms of data acquisition, processing, analysis and geological interpretation for the upper soft and lower hard strata. The continuous high precision stratigraphic profiles are obtained, and the existence of boulder stone and bedrock intrusion is precisely identified,which is verified by the geological drillings. Based on the microtremor survey results, some pretreatment measures have been applied to those high-risk area accordingly, achieving the good engineering effects. 2020 Vol. 57 (5): 43-50 [Abstract] ( 792 ) [HTML 1KB] [ PDF 4647KB] ( 1156 ) 51 Seismic Vulnerability Analysis of the Shallow-buried Shield Tunnel in Soft Soil Stratum HUANG Zhongkai1 ZHANG Dongmei1,2 Taking a typical shallow-buried tunnel in soft soil stratum as an example, corresponding dynamic finite element model is established using the software ABAQUS to carry out a series of nonlinear time-history analyses.Seismic vulnerability analysis of the typical shallow-buried tunnel is conducted considering the uncertainties of site soil layer, input seismic wave and the impact of soil-structure contact effect, corresponding curve is obtained, and a contrastive analysis between this curve and existing similar vulnerability curves is carried out by taking the ratio of load bearing capacity to bending moment of lining section as damage index. The results show that the softer the soil layer, the higher the seismic vulnerability, highlighting the significant role of local soil conditions in the vulnerability analysis of tunnel. The seismic vulnerability curve quantitatively describes the probability of structural performance level of the shallow-buried tunnel under different earthquake intensities, which can provide reference and basis for the similar tunnel in terms of seismic performance analysis, loss evaluation and risk assessment. 2020 Vol. 57 (5): 51-60 [Abstract] ( 859 ) [HTML 1KB] [ PDF 4968KB] ( 933 ) 61 Research on Crack Identification of Highway Tunnel Linings Based on Data Obtained from the Testing Vehicle JIANG Heng1 LIU Xuezeng2 ZHU Hehua1 With the continuous construction of highway tunnels, the problems of disease identification and mainte? nance of highway tunnels are increasing. The traditional tunnel lining crack identification requires a lot of personnel to participate in the indoor work, resulting in low efficiency. Based on the image data collected by the rapid testing vehicle for highway tunnel condition, this paper uses the convolutional neural networks to train a set of models for recognizing the cracks in the highway tunnel linings. According to the problems found in the training process, a comparative study on the effect of different crack data sets on the recognition effect of the neural network models is carried out, proving that the CNN model trained by images sorted by crack development trends has better recognition ability and better applicability. 2020 Vol. 57 (5): 61-65 [Abstract] ( 861 ) [HTML 1KB] [ PDF 2577KB] ( 1383 ) 66 On Mechanism of Crystal Blockage of Tunnel Drainage System and Preventive Countermeasures TIAN Chongming1 YE Fei1 SONG Guifeng2 WANG Qinglong2 ZHAO Meng1 Crystal blockage in tunnel drainage pipe brings much trouble to tunnel construction and operation. Through field investigation and literature research, this paper analyzes the mechanism of crystallization and blockage of tunnel drainage pipe, and puts forward prevention suggestions. The main conclusions are as follows: The crystallization of tunnel drainage pipe is segmental, the crystallization of NaHCO3 underground water is serious in the tunnel under construction, the crystal composition is CaCO3, the pH and alkalinity of the solution flowing out of the primary support and drainage pipe are very high. In general, the lower the water flow rate, the greater the amount of crystallization. The crystallization and blockage of tunnel drainage pipe can be divided into four processes, i. e. chemical reaction between groundwater and shotcrete, concrete erosion by groundwater, crystal precipitation in drainage pipe solution and deposition blockage. In practical engineering, the four processes may occur simultaneously and interact with each other. The main factors affecting the crystallization and blockage of tunnel drainage pipe include the type of groundwater, the characteristics of shotcrete, the physical and chemical conditions of crystallization of drainage solution and the deposition condition of drainage pipe. Finally corresponding engineering suggestions are proposed from two perspectives of waterproof and drainage design and construction control. 2020 Vol. 57 (5): 66-76 [Abstract] ( 711 ) [HTML 1KB] [ PDF 4109KB] ( 1954 ) 77 Discussion on Connection Problems of Underground Space in Early CBD from the Perspective of Urban Renewal ——A Case of Lujiazui CBD LIU Sicong1 ZHAO Chengqiao2 MA Chenxiao1 PENG Fangle The early constructed CBDs in China usually have a relatively single function, small development scale, and lack of systematic connections. The lack of connection will greatly limit the region to exert higher comprehensive benefits. Starting from the related theories of underground connection, this article summarizes the principles,modes, types of facilities, and temporal and spatial scope of underground space connection. Taking Lujiazui CBD as an example, it explores the urban renewal design method of the early CBDs based on connection theory. 2020 Vol. 57 (5): 77-83 [Abstract] ( 868 ) [HTML 1KB] [ PDF 2904KB] ( 1428 ) 84 Hoek-Brown Criterion Based Calculation Method of Rock Resistant Coefficient in Tunnelling and Its Engineering Application WANG Zhilong1,2 ZHOU Renqiang3 YANG Nie1,2 WANG Mingnian1,2 LIU Dagang1,2 The load-structure method has been widely used in the current tunnel design, so it is very important to determine the rock resistance coefficient reasonably. Taking a deep-buried circular tunnel as the research object,which conforms to the ideal elastic-plastic mode, the stress and displacement of surrounding rock are analyzed base on the Hoek-Brown criterion, which can better reflect the non-linear failure characteristics of rock mass and explain the influence of tensile stress zone and low stress zone on the strength of surrounding rock mass. Then the formula for calculating the rock resistance coefficient is obtained by Winkler hypothesis. Based on the Xiangjiawan tunnel on Zhengzhou-Wanzhou high-speed railway, the engineering application analysis is carried out. The results show that: 1)as for the method of calculating the rock resistance coefficient based on Hoek-Brown criterion, the influences of stress state, structure and strength of rock mass are taken into account, which is more practical; 2) in field application, BQ can be determined by saturated uniaxial compression test, elastic wave velocity test of rock mass and rock, and then GSI can be approximately determined by BQ, finally rock mass parameters can be determined, realizing the quantitative selection of parameters; 3) based on the engineering application in Xiangjiawan tunnel, it is shown that the calculation result of the rock resistance coefficient is close to the recommended range specified in the code, verifying the rationality of the calculation results to some extent. 2020 Vol. 57 (5): 84-90 [Abstract] ( 822 ) [HTML 1KB] [ PDF 2237KB] ( 1149 ) 91 Study on Computation of Surrounding Rock Pressure of Super Large Span and Flat Underground Cavern Based on Process Load Concept SUN Yulong YAN Zhiguo The computation of surrounding rock pressure of 60 m span flat underground cavern is beyond the scope of the existing calculating methods. The empirical formulas and influencing factors are compared and analyzed. Based on Protodyakonov formula, the concept of process load and construction method, the cross section of cavern with super large span is divided into several small span caverns, and the surrounding rock pressure of super large span flat underground caverns is obtained considering the construction process. The relationship between the settlement of crown and the distance from the excavation face, the range and its maximum value of ground surface settlement caused by the advance of excavation are obtained by three-dimensional numerical simulation using finite difference method. Taking the εz of 0.000 25 as the critical strain, the loose scope and pressure load of surrounding rock are obtained. By comparing the calculation results of the three methods(one-cycle construction, process load and numerical calculation) it can be seen that the pressure value of surrounding rock obtained by applying the existing empirical formula directly is larger than the process load value and the numerical calculation result, while the numerical calculation result is similar to the process load value. Therefore, the process load has certain reference signifi? cance for the calculation of the surrounding rock pressure of the super large span flat underground cavern. 2020 Vol. 57 (5): 91-98 [Abstract] ( 791 ) [HTML 1KB] [ PDF 2909KB] ( 973 ) 99 Study of Equivalent Layered Method Based Prediction Model for Deformations Caused by Construction of New Tunnels Undercrossing Existing Tunnels ZHOU Zhong CHEN Yun MIAO Linwu As for the deformations of the strata and the existing structures caused by construction of new metro tun? nels undercrossing existing tunnels, calculation results by conventional prediction methods often have large errors compared to measured data because the complex influences of the existing structures are always neglected. According to the equivalent layered method, an existing tunnel can be considered as an equivalent rock stratum instead.Based on the Peck formula, a theoretical model considering the stiffness of existing tunnels is established to predict the deformations caused by construction of a new tunnel undercrossing an existing tunnel, and a Peck formula solution considering existing stiffness is derived. The validity of the proposed prediction method is verified by analysis of application cases. 2020 Vol. 57 (5): 99-103 [Abstract] ( 820 ) [HTML 1KB] [ PDF 1817KB] ( 1593 ) 104 Numerical Simulation of Ground Subsidence Induced by Shield Tunnel Construction Disturbance in Water-rich Sandy Stratum LV Xilin1,2 ZHAO Yucheng1,2 CAI Jiantao3 Through a three-dimensional elastoplastic numerical simulation of the working face of a shield tunnel, it studies the characteristics of ground subsidence induced by support pressure change and ground loss, analyzes the effect of changes of soil mass parameters and ground water seepage on ground subsidence. The simulation results show that the seepage will significantly increase the support pressure required to maintain the stability of tunnel working face, the magnitude and scope of ground subsidence, and change the pattern of ground subsidence; when the support pressure approaches the limit value, the ground deformation at the top of the tunnel increases sharply;soil deterioration results in increase of ground deformation, and the soil deterioration will have more significant impact on the ground deformation when the supporting pressure approaches the limit value; due to the effect of ground loss, the deformation at the plane on tunnel top is the largest, and the deformation decreases gradually towards the ground surface. 2020 Vol. 57 (5): 104-109 [Abstract] ( 786 ) [HTML 1KB] [ PDF 2119KB] ( 1164 ) 110 Study on the Influence of Coefficients of Subgrade Reaction and Lateral Pressure on Deformation of the Shield Tunnel CHEN Weijie1 SU Dong1,2 CHEN Xiangsheng1,2 PANG Xiaochao2,3 LEI Guoping1,2 In the calculation of internal force and deformation of shield tunnel lining structure, the coefficient of subgrade reaction and the coefficient of lateral pressure are important representational parameters of soil mass.Based on a load-structure calculating model of shield tunnel, the finite element software is used to establish a fine model of the shield tunnel lining structure which considers the effect of bolt pre-tightening force. The influence of the coefficient of subgrade reaction and the coefficient of soil lateral pressure on the deformation of shield tunnel lining structure under the initial loading mode and upper loading mode is studied. The results show that the coefficient of subgrade reaction and the coefficient of lateral pressure of soil mass have a significant effect on the deformation of shield tunnel lining structure, and the ovality of shield tunnel decreases with the increase of the subgrade reaction coefficient and soil lateral pressure coefficient; concrete lining of the shield tunnel begins to yield when the ovality is 33.52 -37.65 mm, and the ovality increment will increase significantly after getting into yielding state; under the same load change, the increment of ovality decreases with the increase of coefficient of subgrade reaction and coefficient of lateral pressure, and the increment of ovality in the upper loading stage is obviously larger than that in the initial loading stage. 2020 Vol. 57 (5): 110-115 [Abstract] ( 783 ) [HTML 1KB] [ PDF 2196KB] ( 1213 ) 116 Research on the Stability and Supporting Parameters of High-Steep Slope of Yankou Highway Tunnel LV Jingfu1 DU Jiangmei1 LUO Zejun2,3 ZHANG Jinjiang1 MIU Yabiao1 As for the tunnel portal section, it is characterized by steep slope, weak and fractured surrounding rock, which is easy to lead to the instability or insufficient strength of the slope. In this paper, based on the portal construction at the Dongchuan end of Yankou tunnel, the 3D finite element software is used to simulate the slope stability, the influence of sheet-pile reinforcement and tunnel excavation on the slope stability is studied, and the sensitivity analysis of the anti-slide pile support parameters is carried out. The results show that in the course of tunnel construction, the construction of portal is usually the most unfavorable stage; the stability of the slope under different working conditions is improved obviously when sheet-pile is used to reinforce the slope at the portal; with increase of embedded depth of pile, the maximum stress of pile decreases and the displacement of pile tip decreases; the impact of tunnel excavation on nearby railway can be effectively reduced by adopting sheet-pile support. 2020 Vol. 57 (5): 116-124 [Abstract] ( 824 ) [HTML 1KB] [ PDF 4959KB] ( 1379 ) 125 Analysis of Mechanical Properties of Innovative Support System in Loess Tunnels WANG Zhichao XIE Yuan XIE Yongli To satisfy the construction safety of loess tunnels in special sections, it is important to strengthen the initial support to intervene in the stress state of surrounding rocks as soon as possible. Based on the exploration of a new support structure, this paper proposes the steel-concrete composite structure support system. By changing the stiffness ratio between the initial support and the secondary lining, the support strength can be provided at the initial stage of construction, so as to reduce the occurrence of loose pressure. ANSYS software is used to establish a threedimensional excavation model, the bearing characteristics and component parameters of the steel arch of the composite support structure are analyzed from the perspective of the overall and local forces, and the supporting performance is evaluated through comparison with the common support system. The results can provide reference for the study of the new support structure of loess tunnels. 2020 Vol. 57 (5): 125-135 [Abstract] ( 731 ) [HTML 1KB] [ PDF 5730KB] ( 1458 ) 136 Research on Anti-seismic Technology of Super Large Section Highway Tunnel in Fault Fracture Zone LIANG Bo1 YANG Shiheng 1 REN Zhaodan2 ZHAO Fengbing 1 It analyzes the anti-seismic technology of highway tunnel with super large section in fault fracture zone by 3D finite difference calculation software. Through numerical simulation, the influences of different stiffness of lining structures and grouting reinforcement means on the anti-seismic effet of tunnelling in fault fracture zone are analyzed. The results show that the stress of concrete lining with larger stiffness is larger, and the longitudinal influence range has a tendency of slightly increases; with the decrease of lining stiffness, the decrease trend of maximum principal stress is not linear and has an obvious trend of slow down, and the damping effect becomes less obvious after continuous reduction of lining stiffness; the grouting reinforcement has obvious anti-seismic effect on arch foot and haunch of the super large section tunnel in fault fracture zone, which will improve the condition of force on tunnel lining; the anti-seismic effect of full ring grouting at intervals is better than that of full ring contact grouting; it is suggested that grouting at intervals of 1 m and 4 m in thickness should be adopted at the fault fracture zone of the super large section tunnel. 2020 Vol. 57 (5): 136-142 [Abstract] ( 655 ) [HTML 1KB] [ PDF 2400KB] ( 900 ) 143 Analysis of Mechanical Behavior of Shield Tunnel Openings Based on ShellContact Model GUAN Panfeng1 GUO Zhenkun2 WU Pengli2 LIU Xian2 Taking the mined metro staion constructed with large-diameter shield tunnel as background, and based on the shell-contact numerical calculation model, this paper makes a numerical analysis on the whole process of large-size opening of shield tunnel under the protection of internal support system,using the shell element to simulate the lining segement, the yielding spring to simulate longitudinal and circumferential bolts, and considering the coupling of compression and shearing of longitudinal and circumferential bolts. The aimes of this paper are to analyze the mechanical behavior of shield tunnel segement lining in the whole process of tunnel opening, to study the structural force transfer mechanism of lining structure when tunnel opening and internal supports removing, to determine the effect law of the longitudinal joint position on the segement lining response when the tunnel opening, and the importance of the internal support system, providing design suggestions for relevant shield tunnel opening. 2020 Vol. 57 (5): 143-153 [Abstract] ( 605 ) [HTML 1KB] [ PDF 4525KB] ( 1257 ) 154 Research on Prediction of TBM Driving Parameters Based on Deep Learning LI Gang1 LI Xiaojun1 YANG Wenxiang2 HAN Dong1 With continuous application of the full face tunnel boring machine (TBM) in tunnelling, the adaptive ad? justment of TBM driving parameters becomes more and more important. Because it is difficult to accurately predict the geological conditions before excavation, it is important to predict some important driving parameters such as cutter head torque and total thrust based on the field monitoring data for the adaptive adjustment of TBM driving parameters. Taking the TBM3 lot of Jilin Water Supply Project as the research object, it introduces the long short-term memory network (LSTM) which can consider the data time correlation, and puts forward a model which can accurately predict the total thrust and cutter head torque of the stable section according to the driving parameters of first 30 s of the rising section of TBM driving cycle. The prediction results show that the prediction accuracy of the total thrust and the cutter head torque in the stable section is high, up to 91% and 89%, respectively. Compared with the ran? dom forest, LSTM can make full use of a large number of TBM driving parameters, reflecting a better prediction ability. The research in this paper has a certain reference value for the real-time adjustment of TBM driving parameters. 2020 Vol. 57 (5): 154-159 [Abstract] ( 943 ) [HTML 1KB] [ PDF 2122KB] ( 1524 ) 160 Analysis and Prediction of Driving Parameters of Shield Tunnelling in Complex Strata SHEN Xiang1 YUAN Dajun2 WU Jun3 FU Yanbin1 Taking the running tunnel from Gangwan square station to Zhongshan square station of Dalian Metro as background, the control technique and change law of driving parameters are analyzed for shield tunnelling in the mixed strata including full face hard rocks, uneven hard and soft rocks, and uneven weathered rocks. According to this law, the optimization suggestion on driving parameters are given. In light of the grey system theory, GM (1,1) prediction model is introduced to predict the total driving thrust. The results show that the predicted thrust value is close to the actual driving data. It′s explained that using this model the driving parameters in short term can be predicted for shield tunnelling in complex strata. 2020 Vol. 57 (5): 160-166 [Abstract] ( 743 ) [HTML 1KB] [ PDF 3253KB] ( 1401 ) 167 Analysis of Impact Load and Vibration Response of Shield Disc Cutters in Soil-rock Composite Strata SUN Jiacheng1 LIAO Shaoming1 SUN Lianyong2 MEN Yanqing2 LIU Mengbo1 When the shield machine drives in the soil-rock composite strata, the cutters will be subjected to im? pact loads at the soil-rock interface due to the uneven properties of ground, causing the strong vibration of the cutterhead, threatening the stability of the shield machine and surrounding environment. Based on the actual construction situation of a running tunnel of the Jinan metro line R2, three-dimensional dynamic numerical method is used to build the finite element model of single disc cutter cutting composite strata under different conditions. Then the impact load response of single disc cutter and the relationship between the impact load and influencing factors are analyzed under different conditions of penetration, cutting speed and rock hardness. The frequency distribution characteristics of the impact load response of single disc cutter are obtained by Fourier transform of time-history curve of load response under typical working conditions. The results shows that the vertical force on a single disc cutter is positive correlated with the penetration, cutting speed and rock hardness; the frequencies of loads on the disc cutter are mainly distributed in the range of 0-20 Hz, with increase of the penetration, cutting speed and rock hardness, the amplitude of low-frequency load increases while a small amount of load frequency being distributed around 50 Hz. 2020 Vol. 57 (5): 167-176 [Abstract] ( 704 ) [HTML 1KB] [ PDF 4056KB] ( 901 ) 177 Aseismic Performance-based Optimal Analysis on the Installation Location of Directly Buried Gas Pipeline beyond the Utility Tunnel ZENG Gehua1,2 With the current guiding opinion for ingathering of municipal pipelines into the utility tunnel, the subhigh and high pressure gas pipeline would not be accommodated in utility tunnel. Considering the different position relations between directly buried gas pipeline and utility tunnel, multiple engineering conditions are set and the earthquake dynamic response of directly buried gas pipeline in each condition are calculated by numerical simulation in this research. The calculation results indicate that: (1) the utility tunnel could weaken the earthquake dynamic response of nearby directly buried gas pipeline, in other word, the seismic behavior of gas pipeline buried nearby utility tunnel is better; (2) under the action of earthquake, if the directly buried gas pipeline locates on the right above of utility tunnel, the decreasing extents of earthquake acceleration, displacement and stress are the highest,and the larger the spacing the smaller the amplitude if the gas pipeline locates at two sides of utility tunnel. Thus some suggestions are given to the location of directly buried gas pipeline: (1) if the utility tunnel locates right below the municipal road, the gas pipeline should buried within the central green belt; (2) if the utility tunnel locates un? derneath the non-motorway at two sides of road, the gas pipeline should buried within the green belts at two sides of road. 2020 Vol. 57 (5): 177-183 [Abstract] ( 717 ) [HTML 1KB] [ PDF 2886KB] ( 892 ) 184 Analysis on Mechanism of Longitudinal Grouting Uplift of Existing Metro Tunnel FU Yanbin1,2 CHEN Xiangsheng1,2 WU Peilin1,2 Compaction grouting uplift is an effective measure to reduce excessive settlement and uneven settlement of tunnels. Based on the cylindrical cavity expansion theory and the image method, the additional uplift force on the existing tunnel caused by compaction grouting is analyzed and the analytical solution of uplift force considering tunnel displacement influence is derived. Then the existing tunnel is assumed as a Timoshenko beam resting on a Vlasov foundation. Considering the shear dislocation between lining rings and the continuity of foundation, a grouting uplift calculation model on existing metro tunnel is established, and a theoretical solution of longitudinal response of tunnel is given. This method is verified through specific cases, the mechanism of tunnel grouting uplift is revealed,and the effect of key factors on grouting uplift is analyzed. The results show that the grouting uplift effect is sensitive to the change of soil elastic modulus at the bottom of the tunnel, and the influence of the variation on the uplift effect increases with the decrease of the elastic modulus; the grouting order plays a key role in the effect of tunnel grouting uplift. 2020 Vol. 57 (5): 184-192 [Abstract] ( 738 ) [HTML 1KB] [ PDF 2382KB] ( 2678 ) 193 Analysis on Infrared Radiation Temperature Characteristics of Jointed Rock Masses with Different Orientations under Action of Disc Cutters WANG Yanqing ZENG Nianchang LIU Bolong In order to investigate the infrared radiation temperature characteristics of jointed rock masses with different orientations under action of disc cutters, a series of indentation tests are conducted on jointed rock mass with two cutters. The granite block is adopted in the experiment, the joint gap is filled with cement mortar to simulate jointed rock mass, and the jointed orientations of rock samples are set as 0, 30, 45, 60 and 90 degree, respectively. The deformation and infrared radiation temperature of rock surface are measured by digital image correlation system and thermal imager during experiment. The experimental results show it has a good correlation for the characteristics of infrared temperature and fracture of rock mass in compaction stage, elastic stage, plastic stage, failure stage and post failure stage; the joint orientation could change the relative magnitude of tensile stress and shear stress along the trajectory of median cracks, so the thermoelastic effect and frictional heat effect are changed, resulting in different in? frared radiation temperatures in the median crack area; the failure moments and positions of jointed rock mass can be determined by differential thermograms, and the infrared radiation abnormity area in the differential thermograms is deemed as the sign of rock failure. 2020 Vol. 57 (5): 193-199 [Abstract] ( 788 ) [HTML 1KB] [ PDF 4703KB] ( 1147 ) 200 Model Test Study on Mechanical Behaviors of Tunnel Construction in Soft and Fractured Surrounding Rocks TIAN Xingchao LIU Yuanming TAO Tiejun YANG Jiazhao MA Zhili In order to understand the mechanical behaviors of the super-long tunnel in soft and fractured surround? ing rocks under different construction methods and to find out an efficient and safe construction method suitable for the geological conditions, indoor simulation of tunnel excavation by three construction methods under six working conditions are conducted by means of core sampling at site, measuring of mechanical parameters of surrounding rock and preparations of similar material and primary support material based on a tunnel project, and the characteristics of stress field of surrounding rock and response of internal force of support system under different working conditions are studied. The results show that: when the water cement ratio is 1∶1.6, the initial support of C25 shotcrete can be simulated; the three-bench method is not suitable for tunnel excavation in this geological condition due to the large disturbance to the surrounding rock in front of the tunnel and the large load on the initial support, and other methods can ensure the safety and stability of tunnel construction. Considering the construction progress and construction cost, the method of three-bench with reserved core under case M4 is the best; after the completion of tunnel excavation and support under different working conditions, the maximum internal force of shotcrete initial support occurs at the side wall and follows by the arch foot, and the smallest one occurs at vault. 2020 Vol. 57 (5): 200-209 [Abstract] ( 733 ) [HTML 1KB] [ PDF 6628KB] ( 1220 ) 210 Field Test of Pull-out Resistance of the Tension Anchor in Cohesive Soils LI Qiang1 FU Wenguang2 LI Bo2 Shenping anchor test is a large comprehensive test programme, in which several methods are used to test the mechanical properties, lengthes and test methods of anchor bolts. Type B anchor bolt is a one-pass grouting tensile anchor in cohesive soils. A total of 16 anchor bolts with different lengths are divided into 4 groups, and the test results show that: (1) the stability criterion proposed in this paper is that the shortest load observation period is 15min, the creep rate is 2.0 mm, and the initial moment of the calculation period is not shorter than 5 min, proving the shorter test time and higher accuracy compared with the 7 types of judgment methods adopted in domestic standards; (2) for the tensile anchors in the cohesive soil layers, when the length does not exceed 18 m, the bond stress is approximately evenly distributed along the anchor rod; (3) in the granite residual soil layer, the effective bond length is not less than 18 m; (4) under the precondition of conventional construction and one-pass grouting, the average bond strength between grout and granite residual soil layer is 103.7 kPa. 2020 Vol. 57 (5): 210-217 [Abstract] ( 634 ) [HTML 1KB] [ PDF 1747KB] ( 1017 ) 218 Experimental Study of Influence of Fan Combinations on the Performance of Ventilation and Ceiling Exhaust System of a Metro Running Tunnel CHEN Fangxing1 WANG Haiqiao1 CHEN Shiqiang1 TIAN Feng1,2 ZHU Zhulong2 Based on the metro running tunnel section from Wawuzhuang station to Guizhou Road station of Qingd? ao metro line 1, a physical model of ventilation and exhaust system is built. In light of the fan combinations of option1 (Two forced fans + two exhaust fans), option 2 (Two forced fans + one exhaust fan on the left side of a smoke ceiling vent) and option 3 (Two forced fans + one exhaust fan on the right side of a smoke ceiling vent), an analysis is conducted and the input variable frequencies, power consumptions, air velocities and static pressures in the left and right carriageways are obtained under the three fan combination options. The experimental data show that the static pressure field in both carriageways are symmetrically distributed with the ceiling smoke vent as the symmetry axis,and characterized by an oscillating phenomenon, whether in option 1, option 2 or option 3. This oscillation exhibits an approximate constant of static pressures, and increase of consumed powers will hardly cause compensatory increase of air volumes, meanwhile it is also a key to evaluate the effects of fan combinations on relative shock loss when air flow passes through ceiling smoke vent. In order to quantify the difference of the shock loss (i.e. resistance),a concept of the performance coefficient of the ventilation and exhaust system, and a calculation model of deviation percentage is proposed, with the result of the resistance in option 1 being the smallest under the three combination modes. Thus it is recommended that the option 1 should be a preferential fan combination for an extra-long and large tunnel. 2020 Vol. 57 (5): 218-225 [Abstract] ( 606 ) [HTML 1KB] [ PDF 2901KB] ( 1193 ) 226 Design and Construction Technology of Slurry Shield Used in Shiziyang Water Conveyance Tunnel LU Andian1 XIAO Hui2 SHEN Xiang2 FU Yanbin2 The Pearl River Delta Water Resources Allocation Project aims to solve the water supply problems in the Nansha district of Guangzhou, Shenzhen, Dongguan and other water-scarce areas, as well as the long-term water supply problems of cities in eastern Guangdong. As for the Shiziyang crossing section, it will be faced challenges such as fewer drilling holes, long distances, high water pressure, multiple faults, and large cross-sections. Combining the geological and hydrological conditions of the project, a Herrenknecht slurry balance shield with a diameter of 8.65 m is selected for construction and excavation, and the tunnel structure is designed with emphasis on waterproof and anti-corrosion. According to the stratum and engineering characteristics, the following construction suggestions are put forward: (1) before the project is carried out, the physical and mechanical characteristics of the fault fracture zones shall be explored, and the crossing plan should be fully prepared; (2) experimental research on the abrasiveness and composition of the rock and soil layer should be conducted to find out the wear rule of the cutter tool in the rock and soil layer; (3) new grouting materials need to be researched to form a material-theory integrated grouting system for crossing the fault zone. 2020 Vol. 57 (5): 226-231 [Abstract] ( 713 ) [HTML 1KB] [ PDF 2887KB] ( 1405 ) 232 Study on Construction Ventilation Scheme of Air Cabin for An′ding Tunnel on Yumo Railway SONG Junxiu1 WAN Xiaolin2 GUO Chun1 In order to deal with the disadvantages of large local resistance and wind loss in the large-angle bends of the tunnel with traditional ducted ventilation, taking the An′ ding tunnel on Yumo railway as the engineering background, an air cabin ventilation system for tunnel construction is designed by the method of numerical simulation. Based on the fan efficiency, total wind pressure and the smoothness of the air flow in the air cabin, the optimal dimension of air cabin is determined by using controlled variable method. The calculation results show that the ventilation efficiency is high, the air cabin requires less material which is more economical and practical, the air pressure of the four fans is balanced, the fans are well coordinated, and the air flow field in the air cabin is uniform and stable when four SDF No. 12.5 axial fans are equipped to supply air to each working face of the tunnel and the dimensions of the air cabin is 18 m long and 4.5 m high and the space between fan centers is 8 m. 2020 Vol. 57 (5): 232-238 [Abstract] ( 714 ) [HTML 1KB] [ PDF 2623KB] ( 1353 ) 239 Optimal Design of the Cutterhead of the Earth Pressure Balance Shield Used in Lanzhou Metro in Water-rich Sandy Cobble Stratum SUN Hongbin1 JIN Shihe1 WEI Yanlong2 DING Jun2 Taking the driving of the earth pressure balance shield used in Lanzhou metro in water- rich sandy cob? ble stratum with large grain size as the background, a series of studies are conducted regarding serious wear of cutting tools, frequent stucking of cutterhead and screw conveyor, difficulty to reach earth pressure balance and so on,and optimal design is carried out in terms of the type of cutterhead structure, cutterhead opening ratio, cutting tool improvement, rated torque of cutterhead and the screw conveyor. The practice shows that the shield driving efficiency increases by 1 time, the cutterhead torque reduces by 20%, the frequency of cutting tool replacement decreases by about 50%, and the mud-cake and surface settlement controlling are significantly improved. 2020 Vol. 57 (5): 239-242 [Abstract] ( 834 ) [HTML 1KB] [ PDF 1508KB] ( 933 ) 243 Safety Control Technology for the Newly Constructed Shield Tunnels Approaching Existing Metro Lines Underneath YAO Xiaoming1 SHU Bo2 LI Bo It poses severe challenges to the normal operation of existing railway lines and the safe construction of the under-constructed projects when the metro shield construction underneath passes through existing railway lines,so the proper construction measures to be adopted are essential. Take a new shield tunnel in Chengdu as the background, a construction method for the shield tunnel underneath existing railway line is discussed, a pipe-roof test is conducted, the countermeasures for risks are proposed, and the monitoring measures and plans for potential risk sources are established. The practical effect shows: the design scheme for the shield passing existing railway line underneath meets the relative specifications and standards requirements of existing railway line; detailed scheme for risk prevention and controlling should be established aiming at different risk sources as for the various projects passing through underneath, and monitoring and measuring should be emphasized to give a scientific feedback to the observational construction. 2020 Vol. 57 (5): 243- [Abstract] ( 676 ) [HTML 1KB] [ PDF 4677KB] ( 1559 )

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