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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2020 Vol.57 Issue.3 Published 2020-06-25 1 Discussion on the Construction Management of Sichuan-Tibet Railway Tunnel Based on System Engineering Methodology MA Hui1 GAO Mingzhong2 In order to comprehensively improve the ability and means to deal with the complex problems in the con? struction of the Sichuan-Tibet railway tunnel project, a tunnel construction management system for the Ya ′an-Linzhi section of the Sichuan-Tibet Railway is established based on system engineering methodology by taking time dimension, logical dimension, knowledge dimension and environmental dimension as the basic structure. Aiming at the main challenges faced by the Sichuan-Tibet railway tunnel project, it systematically summarizes the countermeasures for the key issues of engineering survey and design, special unfavorable geological condition, construction organization and management in view of the different stages of time dimension, goals of logical dimension and through technology accumulation and research of knowledge dimension,providing a reference for the construction and management of tunnel project of Ya′an-Linzhi section. The research indicates:(1) the tunnel project is critical for the entire Sichuan-Tibet Railway, and so a system engineering methodology based full-cycle construction management system should be established; (2) the main technical challenge of the Sichuan-Tibet railway tunnel is the special complex geological condition, related solutions should be put forward in the feasibility study and design stages and further application research should be conducted in implementation stage to guarantee effectiveness and reliability of the countermeasures; (3) in light of the harsh environmental conditions, extreme geological challenges and super-long construction period of the Sichuan-Tibet Railway tunnel, a higher level of“Four Modernizations”and breakthrough in management innovation are required; (4) aiming at the complexity of the construction and management of the SichuanTibet railway tunnel, no participant can independently handle the management risks of this huge system project and it is necessary to establish a higher-level full-cycle integrated management mechanism, implementing stricter ecological environmental protection and organizing stronger scientific and technological innovation support. 2020 Vol. 57 (3): 1-8 [Abstract] ( 945 ) [HTML 1KB] [ PDF 2004KB] ( 2386 ) 9 Study on the Location Selection of Emergency Rescue Station of the Extra-long Railway Tunnel at High Altitude WANG Mingnian1,2 GUO Xiaohan1,2 YU Li1,2 LI Chunhui1,2 CHEN Shuwang3 In order to provide a theoretical basis for the location selection of emergency rescue station of the long railway tunnel at high altitudeand to improve the design requirements for disaster prevention and evacuation of highaltitude railway tunnels, taking the typical extra-long double-track tunnel at high altitude as the background, a fullscale fire model and evacuation model are established by using FDS and Pathfinder. By analyzing the vertical visibility,distribution laws of temperature and required safety evacuation time(RSET) of different locations of emergency rescue stations at different altitudes, the available safety evacuation time(ASET) and required safety evacuation time（RSET） in each case are obtained, thus the locations of emergency rescue station at different altitudes are determined. The results show that: under the altitude of 3 000-4 000 m, the ASET and RSET both meet the requirements of 6 min; the location selection of high-altitude railway tunnel should be based on the principle of minimum RSET;under the altitudes of 3 000 m, 3 500 m and 4 000 m, the optimal locations of the emergency rescue stations are 10km, 20 km and 15 km away from the portal respectively. 2020 Vol. 57 (3): 9-14 [Abstract] ( 846 ) [HTML 1KB] [ PDF 2053KB] ( 1659 ) 15 Research and Application of Support Resistant Limiting Dampers in the Tunnel with High Horizontal Geostress LI Chang1,2 WANG Gang1,2 QIU Wenge1,2,3 GONG Lun1,2 ZHAO Yingchun4 WANG Qiuhui4 In order to deal with the failures of primary lining of Ruyi tunnel on Menghua railway with high geo? stress, through theoretical analysis, numerical simulation and on-site construction feedback methods, the engineering application method and action mechanism of the support technique with resistance limiting and energy dissipation are studied based on laboratory test, geostress testing and field monitoring data.The results show that:(1) under the condition of high tectonic stress, the tunnel support with high ductility and resistance limiting is feasible since it can controllably guide the deformation,energy release and transfer of surrounding rocks under the premise that the bearing capacity of surrounding rock is not obviously reduced and the loosening pressure is not obviously increased;(2) the support resistant limiting damper(SRLD) is a reasonable and effective supporting means with high ductility and it successfully solves the problem of primary support failure in Ruyi tunnel with high geostress; (3) the SRLD significantly reduces structural internal force but also changes its distribution, thus further improvement is needed in practical application. 2020 Vol. 57 (3): 15-29 [Abstract] ( 850 ) [HTML 1KB] [ PDF 4289KB] ( 1709 ) 25 Preliminary Study on the Classification Indexes of Surrounding Rock for the Highway Tunnel in Nearly Horizontal Red-bed Stratum LIAO Jun1 DONG Qian1 LIANG Hongyong2 JIAN Bo2 SHI Yuchuan1,3 GONG Hongwei1 As for the design and construction of highway tunnel,accurate surrounding rock classification is the pre? requisite for evaluating stability and guaranteeing safety of tunnel construction and operation.The current surrounding rock classification method specified for the highway tunnel is adopted in the construction of a highway tunnel in nearly horizontal red-bed stratum, and it is found that there is a big difference between the classification results and the actual results reflected by self-stability of surrounding rocks. Based on an analysis of the engineering characteristics of the surrounding rocks of tunnels in nearly horizontal red-bed stratum, it analyzes the causes and tries to correct the correction factor of underground water effect, and the stratum thickness effect factor is added, which makes the current classification method of surrounding rocks be suitable for the highway tunnel in nearly horizontal redbed stratum. The applicability of classification indexes is preliminary verified by practical engineering case, and the results obtained by the corrected classification indexes of surrounding rock meet the requirements for the stability evaluation of surrounding rocks during the design and construction of the highway tunnel in nearly horizontal redbed stratum. 2020 Vol. 57 (3): 25-29 [Abstract] ( 794 ) [HTML 1KB] [ PDF 595KB] ( 1656 ) 30 Study on Geological Prediction Technology of HSP Method for TBM Tunnel LU Song1,2 WANG Xu1,2 LI Cangsong1,2 MENG Lu1,2 In order to reduce the influence of geological prediction on construction procedure and realize efficient geological prediction for TBM tunnels, this paper analyzes the key points and difficulties of geological prediction in TBM tunnel considering the construction environment, introduces the principles and detection scheme of HSP method which is suitable for the TBM tunnels. The HSP method can directly use seismic waves excited by TBM cutters as source signal and obtain stratigraphic characteristic parameters by adopting the technologies of multichannel, longtime, sequence receiving,correlation interference and focusing imaging during data acquisition, realizing geological prediction in front of tunnel working face. The HSP method is applied to a double shield TBM tunnel and the prediction results are in good agreement with the actual geological conditions of the surrounding rocks, it shows the HSP method is one of the efficient geological prediction methods suitable for TBM tunnels. 2020 Vol. 57 (3): 30-35 [Abstract] ( 936 ) [HTML 1KB] [ PDF 2360KB] ( 1485 ) 36 Discussion on Design for the Liangjiang Ship Sightseeing Tunnel ZHONG Zuliang1,2 GAO Guofu1, 2 CHEN Peng1 YAN Ru1 In order to solve the problem of ship detour because of the rivers separated by mountains and cities in ur? ban tourism and to effectively organize the sightseeing and navigation along rivers, a discussion is conducted on tunnel site selection, entrance and exit design, cross-section design and landscape layout, tunnel support parameters and auxiliary facilities of the Liangjiang ship sightseeing tunnel in Chongqing through data collection and on-site investigation in light of the topography, geological structure and human landscape distribution characteristics of the Yuzhong district of Chongqing, and a design plan of Chongqing Liangjiang ship sightseeing tunnel is proposed. 2020 Vol. 57 (3): 36-42 [Abstract] ( 744 ) [HTML 1KB] [ PDF 3151KB] ( 1580 ) 43 Application Research of BIM Technology in Engineering Design of the Immersed Tube Tunnel HUANG Fujie HE Zegan ZHANG Weimin LIU Shanshan Taking a case application of BIM technology in the design of Ruyifang immersed tube tunnel for exam? ple, the general framework of BIM application is discussed, an exploration research on engineering modelling, application method and process is conducted from the aspects of establishing of 3D parameterized model, information model and application of the BIM technology based on information model, and the problems existing in the application of BIM technology in the immersed tube tunnel design are revealed. With the continuous updating of relative software and exploration of BIM modelling and application, the application of BIM technology in the immersed tube tunnel design will be more efficient, convenient and go further. 2020 Vol. 57 (3): 43-48 [Abstract] ( 801 ) [HTML 1KB] [ PDF 2785KB] ( 1733 ) 49 Application of FEM Strength Reduction Method in Stability Analysis and Control of Tunnel Construction TANG Xiaosong1, 2 ZHENG Yingren3 WANG Yongfu1 FEM strength reduction method has been more widely used in the stability analysis of slope engineering rather than tunnel engineering. In this paper the FEM strength reduction method is adopted in a stability analysis and control of tunnel engineering, and a dynamic evaluation on the surrounding rock stability in whole construction process is proposed based on the safety factor. The dynamic controlling indexes of tunnel monitoring and measurement during construction are established by studying the deformation law of tunnel surrounding rocks. The analysis on calculation examples show that the dynamic evolution law of surrounding rock stability during construction can be mastered quantitatively and visually based on the safety factors of rock mass; the corresponding deformation control indexes can be determined for different construction stages under premise of meeting the stability requirements of surrounding rocks after installing primary support so as to overcome the limitation of taking the permissible displacement of surrounding rocks as the criteria of tunnel stability. 2020 Vol. 57 (3): 49-55 [Abstract] ( 738 ) [HTML 1KB] [ PDF 3382KB] ( 1400 ) 56 Study on Stability of Surrounding Rock Based on Strength Reduction Dynamic Analysis Method WU Bo1,2 LAN Yangbin1,2 YANG Shisheng1,2 YANG Jianxin3 PANG Xiaoyu3 To obtain the stability and critical instability failure mode of surrounding rocks after tunnel blasting ex? cavation, based on Jinjing Tunnel of Xingquan Railway, the dynamic safety factor of surrounding rocks of tunnel face is analyzed by using the strength reduction dynamic analysis method in light of the three dynamic instability criteria, i.e., whether the displacement of characteristic point is abrupt, whether the plastic zone is through and whether the calculation is convergent, and the effects of tunnel blasting on overall safety factors under different excavation methods, different advance rates and different surrounding rock grades are studied. The results show the safety factor of full-face blasting excavation is about 0.96 times of that of upper and lower bench excavation; the smaller the advance rate, the larger the overall safety factor; the larger the surrounding rock grade, the better the stability of surrounding rock of tunnel working face under blasting excavation; the safety factor of tunnel with no support after blasting is greater than 1.30. The stability of tunnel working face is quantitatively evaluated by safety factor,and re? duction of advance rate and upper & lower bench blasting excavation method can be adopted in order to make the surrounding rocks be more safe and stable after excavation. 2020 Vol. 57 (3): 56-64 [Abstract] ( 759 ) [HTML 1KB] [ PDF 3381KB] ( 1382 ) 65 Study on the Influence of Parallel Fold Structure on Deformation of Tunnel Surrounding Rocks ZHOU Cuiying1,2 LI Ang2,3 LIU Zhen1,2 Bending deformation of rock strata occurs due to force and fold structure is formed thereof, further it is liable to have deformation failure of tunnel surrounding rocks under influence of complex geological structure and geostress, affecting tunnel stability. Aiming at the surrounding rock deformation of tunnel which is parallel to fold axis and passing through fold structure geology, finite difference method is adopted to conduct numerical simulation and calculation, to explore the deformation law, and to put forward the thought of deformation control of tunnel surrounding rocks. The results show that deformation is more likely to occur at tunnel crown and invert and mainly concentrated in the soft rock stratum and the soft-hard rock interface when the tunnel passes through the parallel fold structure with being parallel to the fold axis, specifically they are at the upper boundary of synclinal soft rock stratum and the lower boundary of anticlinal soft rock stratum, and it is considered to control deformation at tunnel crown and invert and to reinforce the soft rock stratum of parallel fold structure to reduce the deformation of tunnel surrounding rocks. 2020 Vol. 57 (3): 65-74 [Abstract] ( 744 ) [HTML 1KB] [ PDF 7018KB] ( 1443 ) 75 Study on the Mechanical Behaviors of High-filled Loess Arched Open Cut Tunnel under Different Load Reduction Measures MA Li1 LIU Yapeng2 LI Sheng3,4 LV Wenda5 XIE Chao3,4 DAI Jinpeng3,4 Compared with the conventional open cut tunnel, the applied load is larger and the structure is more complex concerning the high-filled open tunnel. It is not clear if the soil pressure change after load reduction is favourable for the tunnel structure in terms of mechanical behaviors. A Study on the mechanical behaviors of trench type high-filled arched open cut tunnel in loess under two load reduction measures is conducted through in door model test, and the law of soil pressure and lateral stress varying with fill height around the open cut tunnel and the load reduction effect are obtained. The test results show that the soil pressure above the arch can be transferred to the two sides of open cut tunnel due to the load reduction measures of EPS plate, EPS plate and geogrid, which reduces the soil pressure on the vault and arch bottom and increases the soil pressure on both sides; the stress on each section outside tunnel is reduced, and the orders in terms of effect of the load reduction materialon external stresses at different sections are haunch, side wall, vault, spandrel and arch bottom. A numerical simulation analysis on the test procedure is under taken by FEM strain model, with the results indicate that the average relative errors between the soil pressure, lateral pressure and the test results are 11.7% and 14.6%; load reduction of internal force increases with an increase of fill height and its change rate increases. For the load reduction of trench type open cut tunnel,it is necessary to reasonably select load reduction material and foundation stiffness under the condition of guaranteeing the safety of lining structure of open cut tunnel. 2020 Vol. 57 (3): 75-84 [Abstract] ( 751 ) [HTML 1KB] [ PDF 5070KB] ( 1360 ) 85 Analysis of the Mechanical Behavior of Segments of the Shield-driven Metro Tunnel beneath River Bottom ZHANG Bingwu1 ZHANG Peng1 DAI Zhenhua2 WU Yinghe2 LUO Wei2 Compared with other sections of a shield tunnel, the engineering geology and hydrogeological conditions of the shield tunnel section passing through river are more complex, especially in southern China where the seasonal precipitation is large, the surface and underground water levels change obviously. Taking certain section of the shield tunnel on Foshan metro line 2 as the research object, it carries out a numerical analysis on segments usingAbaqus finite element software based on a beam-spring model, and verifies with the measured axial forces of segments. The results show the earth pressure on segment is slightly smaller than that calculated by the full-covered earth pressure method; water pressure around the shield tunnel has great influence on internal force of segment, the fissure water and confined water in rock stratum should be taken into account in the design of segment even if the rock layer above shield tunnel is poor in water permeability,and the earth pressure acting on segment is calculated with the full-covered earth pressure for the sake of security. 2020 Vol. 57 (3): 85-90 [Abstract] ( 780 ) [HTML 1KB] [ PDF 2424KB] ( 1254 ) 91 Numerical Simulation Analysis of SF6 Gas Leakage in Extra-Long GIL Utility Tunnel SUI Xin1 ZHANG Zhengwei1 MING Xuan2 DOWNIE Steven3 PADHANI Shahid3 ZHAO Libo4 Since the GIL lines are filled with SF6 gas, there is a possibility of leakage accident of SF6 gas in GIL utility tunnel due to manufacturing, transportation, installation and aging, so the corresponding monitoring,control system and effective exhaust system should be established. Based on the 6.3 km super-long GIL cabin of the underground utility tunnel at Wuhan Tanxinpei road, the most unfavorable leakage position and working condition after gas leakage are determined considering the data of heat-exhaust ventilation and SF6 gas diffusion characteristics.With the open source computational fluid dynamics software OpenFOAM,a 3D long-segment model and a detailed short-segment model for SF6 gas diffusion are set up, and the numerical analysis process is presented. The boundary condition is based on the data extracted from heat-exhaust ventilation analysis, the typical accident conditions of SF6 gas are analyzed and the variation trend of SF6 gas concentration field in GIL cabin is obtained. The analysis results show that SF6 gas is mainly discharged by the conventional exhaust ventilation system and the auxiliary system can largely save the exhaust time. The numerical simulation method can provide reference for the simulation of other types of heavy gas leakage and diffusion in the pipe gallery. 2020 Vol. 57 (3): 91-98 [Abstract] ( 827 ) [HTML 1KB] [ PDF 3663KB] ( 1129 ) 99 Numerical Simulation of Water Burst in Roadway Excavation with Karst Cave Ahead ZHANG Kefeng In order to research the influence of karst cave ahead of roadway on surrounding rock stability, a numeri? cal model is established by FLAC3D considering the interaction of seepage, stress and damage,the variation charac?teristics of stress, deformation, plastic zone and seepage field of surrounding rocks during excavation are analyzed.The numerical results show that：(1) when working face is close to krast cave, the karst cave has certain effect of inhibition to the zonal disintegration of surrounding rock ahead of roadway; (2) with the decrease of distance from karst cave, the maximum displacement of rock mass will gradually increase and present "abrupt change" characteristics,while the position of maximum displacement will change with the variation of water inflow channel; (3) when waterproof pillar is less than a certain thickness, the water inflow of surrounding rocks will suddenly increase and show obvious water burst; (4) seepageand variation of permeability coefficient of surrounding rocks are the basic reasons to cause collapse, chip off-falling and water inflow. 2020 Vol. 57 (3): 99-107 [Abstract] ( 739 ) [HTML 1KB] [ PDF 4441KB] ( 1225 ) 108 Prediction Model of TBM Advance Rate Based on Relevance Vector Machine ZHANG Yan1, 2 WANG Wei2 DENG Xueqin2 TBM has been widely used in tunnel construction, especially the long distance tunnel attributed to the advantages of strong safety, high construction efficiency and so on. The advance rate of TBM is affected by various factors which have complex correlation besides high uncertainty, and so it is difficult to establish a precise model for predicting the advance rate.A relevance vector machine based TBM advance rate prediction model is proposed by which it can build a nonlinear mapping relationship between various factors and advance rate through learning the samples, precisely predict the samples with only known influential factors. The results obtained from the TBM advance rate prediction show that this model has the advantages of high precision, easy operation and small discreteness. 2020 Vol. 57 (3): 108-114 [Abstract] ( 816 ) [HTML 1KB] [ PDF 1793KB] ( 1210 ) 115 Research on Blasting Optimization of Urban Large Cross-section Tunnel Passing through Stratified Sandstone WU Bo Overbreak and underbreak as well as rock over-damage might occur if drilling and blasting is adopted during the tunnel construction in complex stratified rock mass, not only will it affect the construction progress and cost but also threaten the safety of constructers and tunnel stability. Taking a road tunnel passing through stratified sandstone in southwest China as the background, a research on optimization of blasting parameters is conducted by software LSPP in light of the geological conditions and lithology of the tunnel, and an optimal blasting scheme for the tunnel in sandstone is obtained. The practical application results show the optimized blasting scheme can effectively control the tunnel overbreak and underbreak. 2020 Vol. 57 (3): 115-121 [Abstract] ( 700 ) [HTML 1KB] [ PDF 3262KB] ( 1174 ) 122 Analysis on Construction Safety of a Shield Tunnel beneath Existing ChengduKunming Railway without Pre-reinforcement in Argillite ZHAO Taidong It is critical for the construction safety of a new metro tunnel underneath existing operating railway with? out pre-reinforcement measure. Based on the shield tunnel which is located at east depature and arrival line of Yuanhua depot of phase 1 project of Chengdu rail transit line 9 and approaching existing Chengdu-Kunming railway, it simulates the engineering safety in most unfavorable condition, the feasibility of realizing groundstress compensation through active underpinning by grouting and the sensitivities of track deformation to physical and mechanical parameters changes of soil and rock by FEM software. The research results show that it can compensate stratum stress loss through active underpinning and restrain plastic zone development of surrounding rock, meeting the requirement that vector value of vertical deviation of rail track with 10 m chord should be less or equal to ±0.5 mm during construction of a shield tunnel approaching existing Chengdu-Kunming railway in conditions of argillite stratum,no prereinforcement, train load effect and grouting pressure being 0.30 MPa or more. 2020 Vol. 57 (3): 122-127 [Abstract] ( 592 ) [HTML 1KB] [ PDF 2687KB] ( 1221 ) 128 Study on Creep Characteristics of the Carbonaceous Surrounding Rocks Based on Improved Weertman Model DENG Shengqiang1 LUO Junhui1 MI Decai1 ZHANG Boyu2 ZHOU Shanxiong3 Deformation of surrounding rocks of the carbonaceous rock tunnel is characterized by large magnitude, rapidity, long duration, large disturbance and creep, which is a key technical problem encountered during construction of the carbonaceous rock tunnels. Based on the statistical basis of displacement and temperature variation of the carbonaceous surrounding rocks of Guangxi Hechi-Baise expressway tunnels, a function relationship between temperature and time is established and the Weertman creep model is introduced, the creep characteristics of surrounding rocks is studied from the perspective of mechanism under the correlationof temperature and time, and the mechanism and development law of creep of the carbonaceous surrounding rocks are revealed. The results show that by using the improved Weertman model it can effectively calculate, analyze and predict the creep development law of carbonaceous surrounding rocks under the correlation of temperature and time without considering the osmotic pressure. 2020 Vol. 57 (3): 128-134 [Abstract] ( 606 ) [HTML 1KB] [ PDF 3751KB] ( 1072 ) 135 Study on Real Time Synchronized Correlation between Wave Velocity and Stress of Pea-gravel Backfills HU Mingming1 GAO Yang1 CHEN Jiaqi2 SI Daxiong2 DUAN Yuanyu2 The backfilling and grouting quality of pea-gravel concerns the issue if the tunnel lining and surrounding rocks will work jointly. And it is an effective engineering measure to analyze the engineering quality of pea-gravel backfills through the changes of wave velocity of the pea-gravel backfills. A uniaxial compression test on the backfills of pea gravel is conducted, a real time synchronous test on wave velocity and stress is undertaken during loading test, and the evolution laws of acoustic wave velocity and stress in axial direction during loading on pea-gravel backfills are obtained. The experimental results show that the change of lateral strain of pea-gravel backfills is not obvi0us in elastic deformation stage and the volumetric strain does not reach the inflection point until it approaches the peak stress; at the initial stage of loading, the wave velocity rises rapidly and then increases slowly with the continuous increase of stress and remains basically unchanged at later stage,at the post-peak stage the wave velocity mainly remains at the maximum value until the end of the test, there is no obvious correlation between wave velocity and stress. Based on the relationship between stress and axial wave velocity, a fitting formula for exponential function of stress and wave velocity is obtained, so the quality of pea-gravel backfills can be predicted by the wave velocity obtained by field test. 2020 Vol. 57 (3): 135-140 [Abstract] ( 603 ) [HTML 1KB] [ PDF 3250KB] ( 1182 ) 141 Analysis of the Advantages of Liquid Nitrogen Freezing with Multiple Feed-pip GUO Xiaodong1 HU Xiangdong2,3 With conventional liquid nitrogen supplying type, there are problems of uneven distribution of tempera? ture field and unbalanced development of permafrost for the liquid nitrogen freezing.The freezing uniformity can be improved to certain extent by opening on the liquid-supplying copper pipe but it still has the difficulty of distribution controlling of liquid nitrogen. Based on the prototype experiment of liquid nitrogen, this paper analyzes the superiority of multi-pipe liquid supply on system controlling and improvement of uniformity of liquid nitrogen freezing.The research shows that the multi-pipe supply increases the temperatures inside freezing pipe, pipe wall and soil mass and improves the vertical distribution uniformity of permafrost contour along the freezing pipe, overcomes the difficulty to control the distribution at various liquid supplying holes, guaranteeing the temperature stability inside freezing pipes. 2020 Vol. 57 (3): 141-146 [Abstract] ( 539 ) [HTML 1KB] [ PDF 2080KB] ( 1200 ) 147 Influence of Full-face Grouting of the Metro Tunnel on Ground Surface Heaving LIU Jiqiang1 XU Junwei2 DONG Zonglei3 ZHANG Xuemin3 YANG Junsheng3 Continuous heaving of ground surface occurs at certain mined section of Shenzhen metro due to high in? tensity grouting, with the maximum heaving exceeds 50 cm and no settlement occurrence during the subsequent tunnel excavation. Considering that it mainly consists of sandy cobbles and little coarse sand and fully weathered grani?telocated at the upper part and bottom,an analysis on the causes of ground surface heaving is conducted by theoretical analysis, numerical simulation and field measurement from the aspect of lifting by grouting.The results show that grouting has penetration compaction effect on the loose soil mass of this section and hydraulic fracture occurs under large grouting pressure; the directions of most grouting veins are horizontal;jet grouting pile constructed on the both side of grouting area changes the initial stress state of grouted stratum and increases the degree of ground surface heaving. 2020 Vol. 57 (3): 147-153 [Abstract] ( 618 ) [HTML 1KB] [ PDF 3621KB] ( 1251 ) 154 Measured Noise Distribution Characteristics of Longitudinal Ventilation Fans in Urban Tunnels and Its Application Research TIAN Yangming1 ZHANG Zhigang2 DENG Tao3,4 TIAN Yuan3,4 In order to reasonably predict the distribution law of fan noise in the longitudinal ventilation of urban tunnels and provide reference for the feasibility study of longitudinal jet ventilation of urban pedestrian tunnels, two typical urban tunnels are selected to conduct field test of the noise under the condition of longitudinal ventilation in the tunnel, the noise distributions in the tunnel with single and multiple groups of fans are analyzed, and the noise control standards for the pedestrian tunnel are given. The results show that: the noise in the tunnel is mainly the medium and low frequency noise when the fans are not running, and the highest noise level is concentrated between 1 000-2 000 Hz, noise frequency of the fan is mainly concentrated between 250-4 000 Hz, and the highest noise level is concentrated between 500-2 000 Hz; the fan noise shows a basically linear attenuation tendency in the tunnel when a single group of jet fan is running; when multiple groups of jet fans are running, the distribution pattern of noise level between two groups of fans is symmetric with characteristics of being high on two ends and low in the middle along the longitudinal direction, the noise level is higher compared with that of single group of jet fan, the average noise increment is about 4 dB(A); the noise control standard for the urban pedestrian tunnel is that the noise level at 1.5 m above the ground should not be higher than 65 dB(A), and it is suggested that full jet ventilation mode should not be adopted in urban pedestrian tunnels 2020 Vol. 57 (3): 154-160 [Abstract] ( 618 ) [HTML 1KB] [ PDF 2758KB] ( 976 ) 161 Study on Cover-cut Method for the Super-Shallow High-speed Railway Tunnels beneath an Expressway LI Qiang The construction of high-speed railway tunnel beneath an expressway is characterized by small intersec? tion angle, shallow buried depth, large section, long construction period and high safety risk. Based on the situation of certain super-shallow high-speed railway tunnel beneath an expressway, it systematically studies the construction technology and proposes a cover-cut method: partial road of expressway above the tunnel is closed by regions and the unclosed road keeps normal traffic; the envelop enclosure and cover plate of road in the closed area are con?structed by regions to make the whole section of expressway underneath be paved with the cover plate and resume normal traffic;the foundation pit is excavated under the protection of envelop enclosure and the cover plate, and the tunnel main structure is constructed in foundation pit; gap between top of tunnel main structure and cover plate is filled so as to complete the cover-cut construction of the super-shallow tunnel with large span beneath an expressway. With this technology, the road of expressway above the tunnel is closed by regions, with short occupation time, no effect on normal traffic,unnecessity of road change, and little environmental impact. 2020 Vol. 57 (3): 161-166 [Abstract] ( 670 ) [HTML 1KB] [ PDF 3402KB] ( 1072 ) 167 Monitoring and Control Technology for Blasting Vibration of the Double-arch Tunnel without Middle Drift in Red-bed Soft Rock QIAN Zhengfu1 XU Jinfeng2，3 ZHOU Yingxin1，2，3 ZHOU Biao2,3 XIE Xiongyao2,3 Construction without middle drift is a novel method for the double-arch tunnel, and the blasting excava? tion of the subsequent tunnel will have a vibration impact on the lining structure of the antecedent tunnel. Taking the Chenjiachong tunnel of Chuxiong-Dayao expressway in Yunnan province as an example, it studies the blasting vibration control technology of double-arch tunnel without middle drift in red-bed soft rock. Firstly, the three main influence factors of the double-arch tunnel blasting are analysed: the distance between blasting sources, the explosive charge and stress release. Then automatic vibration monitoring is carried out in the corresponding area of the antecedent tunnel aiming at the three-bench、excavation and two-bench excavation of the subsequent tunnel, and the blasting vibration law of the V-level surrounding rock of the red-bed soft rock is obtained by regression analysis of the monitoring data, the explosive dosage of cutting hole, the numbers of nonel detonator segment and economic energy unloading holes as well as the hole spacing are obtained by back analysis,a layout of the blast holes and blasting scheme are established to meet the needs of the site. The field monitoring data show that the revised critical value of vibration velocity and the optimized blasting scheme meet the safety requirements and guarantee the smooth excavation of the subsequent tunnel and no vibration induced cracking in the concrete secondary lining. 2020 Vol. 57 (3): 167-174 [Abstract] ( 641 ) [HTML 1KB] [ PDF 2905KB] ( 1358 ) 175 Settlement Control Techniques of the Super-shallow Buried Large-span Mined Tunnel underneath an Existing Tunnel BAI Pengcheng Taking the super-shallow buried mined tunnel with large span at the Xibocheng station of Chengdu met? ro line 18 as an example, aiming at the deficiencies of original design of CRD method, a technical scheme for settlement control and optimization of CRD construction of the super-shallow buried large-span mined tunnel underneath an existing tunnel is proposed, the auxiliary measures of jet grouting pile, advance large pipe-roof and condulet grouting are adopted to reinforce stratum, and the small-section bench method of CRD and partitioning lining construction schemes are optimized. The practice shows that the optimized CRD construction method and measures are effective, decreasing the safety risks and speeding up the construction speed and reducing construction cost. 2020 Vol. 57 (3): 175-181 [Abstract] ( 611 ) [HTML 1KB] [ PDF 3665KB] ( 1170 ) 182 Remediation of Water Leakage at Portal of Operating Shield Tunnel ZHONG Wenwen It′ s very often to encounter water leakage at the portal of urban metro tunnel. An investigation is con? ducted aiming at the water leakage diseases at the portal of certain urban operating shield tunnel, and the causes are analyzed. The results show that the main causes of water leakage include disturbance of external soil mass, watercontaining cavity due to non-impacted secondary grouting, and rigid and flexible contact at portal. The key technical points and difficulties are described based on two typical cases of water leakage remediation at portal of operating metro tunnel, and the principles and recommendations for treatment of water leakage at tunnel portal are proposed. 2020 Vol. 57 (3): 182-188 [Abstract] ( 632 ) [HTML 1KB] [ PDF 4556KB] ( 1194 ) 189 Application Research of Selective Flocculant Adopted in the Sand Removing from Shield Slurry WU Xiaoming1 XU Han1 WEI Linchun2 DINA Mulati1 CHENG Guoliang3 It is an important technology for slurry recycling by sand removal in flowback slurry based on chemical principles and also an active measure to promote tunnelling efficiency and environmental protection. By analyzing the molecular structure characteristics of partially hydrolyzed polyacrylamide (HPAM), it reveals that the ionized group and linear soft chain can selectively capture and coagulate tiny inertia rock debris while the clay is still dispersed in the slurry system. The effect of HPAM selective flocculation is verified by experiments like vertical tube pressure test. And analysis and selection are conducted to this kind of chemical agent by taking molecular weight, hydrolysis degree and fortified concentration as the main controlling factors, providing a new method of sand removal for the slurry used in the Yangtze River-crossing shield tunnel of Wuhan metro line 7. 2020 Vol. 57 (3): 189-192 [Abstract] ( 636 ) [HTML 1KB] [ PDF 964KB] ( 1142 ) 193 Experimental Study on Performance of the Self-adhesive Tunnel Waterproof Board WANG Tao ZHU Hequan DU Cunshan JIA Hengqiong Aiming at the channeling water caused by local damage of smooth waterproof board and disadvantage in terms of leakage treatment, it systematically studies the performance of anti-stripping, repeated stripping-bonding and channeling water resistance of the self-adhesive waterproof board by a performance test, and discusses the construction techniques and welding methods. The results show that the self-adhesive glue of waterproof board has selfhealing effect and strong stain-resistant ability, thus the waterproof board can be stripped and bonded with poured concrete for many times, and the anti-stripping strength increases with the increase of concrete strength; the bearing capacity of the waterproof board fixed by nail and hot-melt gasket is much larger than the dead weight of unit area waterproof board, effective fixation is obtained with no effect from the subsequent construction, welding by climbing welder and direct bonding technology can be used for overlapping of water board; as for the full-scale simulation and practical engineering test of pressurized water injection, the water pressure is up to 1.3 MPa and no track of channeling water of the core sample is observed at the position fixed by nail, which means the self-adhesive waterproof board is well bonded with the secondary lining concrete and it has good channeling resistance and advantage for later treatment of tunnel disease. 2020 Vol. 57 (3): 193-198 [Abstract] ( 586 ) [HTML 1KB] [ PDF 3918KB] ( 1254 ) 199 Research and Application of New Techniques of Early Warning and Monitoring for Voids behind Tunnel Lining TAN Wen The void behind tunnel lining is a common quality defect which endangers safe operation of railway. This paper analyzes the main causes of voids at tunnel crown, especially studies the intelligent monitoring technique and video control system, optimizes the injection construction technique with formwork through intelligent early warning system. The successful application in the Lihuading tunnel on Beijing-Shengyang high-speed railway shows this innovative early warning system for lining voids is a great monitoring means which is economic since it can radically solve the problem of tunnel voids at tunnel crown and also reduce the amount of grouting with formwork. 2020 Vol. 57 (3): 199-203 [Abstract] ( 615 ) [HTML 1KB] [ PDF 2707KB] ( 1029 ) 204 Design, Manufacture and Application of the Lining Formwork for Oil and Gas Pipeline Tunnels LIU Ming HU Qian WANG Zhixi JIAO Xinlu The problem of insufficient clearance at the lower part is encountered when the traditional lining trolley is applied to the oil and gas pipeline tunnel with small section, and it blocks construction machinery to go through,results in construction in single tunnel construction process and so slows construction progress.The renovations of miniaturization and automation are conducted by taking the techniques of full-fit of gantry and formwork, slip bearings, integral formwork lifting and automatic control in order to maximize the clearance and make it possible for the construction machinery to pass through and realize synchronous construction of tunnel excavation, primary support and secondary lining installation as well as semi-automatic control of formwork erection in the oil and gas pipeline tunnel. The case application shows that the renovated lining formwork for the oil and gas pipeline tunnel can greatly improve construction safety, quality and efficiency and shorten construction period. 2020 Vol. 57 (3): 204-208 [Abstract] ( 606 ) [HTML 1KB] [ PDF 3273KB] ( 952 )

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