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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2023 Vol.60 Issue.3 Published 2023-06-25 1 A Review of Study on Energy-absorbing Rockbolts and Static/Dynamic Test Methods SONG Zhanping1,2,3 XU Xiaojing1,2 LIU Wei1,2 LI Lingfeng4 In order to solve the problem of large deformation of soft rock and the support problem caused by rock? burst in underground works such as deep tunnels and galleries, researchers have devised the energy-absorbing rockbolts with various deformation energy-absorbing mechanisms in the past few decades, and they have also devised the testing methods and equipment that can quantity the static and dynamic performance of energy-absorbing rockbolts, with many research achievements. In review of the energy-absorbing mechanisms, working performance and static/dynamic performance test methods of the existing energy-absorbing rockbolts and based on the working mechanism of energy-absorbing rockbolt, the energy-absorbing rockbolts can be classified into two types, i.e. material deformation energy-absorbing rockbolt and structural deformation energy-absorbing rockbolt. The testing methods and equipment used for static tension and dynamic impact tests of energy-absorbing rockbolt are systematically explained. Depending on their energy-absorbing properties and deformation capacity, the performance of energy-absorbing rockbolt can be classified as low, medium, high or very high. The application prospect of energy-absorbing rockbolt and its direction research have been examined and predicted. 2023 Vol. 60 (3): 1-13 [Abstract] ( 156 ) [HTML 1KB] [ PDF 7252KB] ( 688 ) 14 Comparison between Shield Method and Drill and Blast Method Regarding Carbon Emission Intensity in Subway Tunnel Construction GUO Yalin1,2 SUN Wenhao3 XU Hongwei3 HE Wei3 CHEN Zheng1,2 GUO Chun1,2 In order to explore the differences of carbon emission between two common construction methods, i. e. shield method and drill and blast method, the construction of some tunnel sections of Shenzhen Metro Line 7 is taken as an example to calculate, by using the carbon emission calculation formula, the carbon emission intensities and contribution ratios of the key emission sources of the two methods in the three stages, i.e. construction materials production, costruction materials transportation and onsite construction. According to the calculation results, the average carbon emission intensity of the shield method is 8,104.4 t CO2eq/km and that of the drill and blast method is 15,124.8 t CO2eq/km, so the carbon emission of the shield method is less. In both methods, the carbon emission in the construction materials production stage exceeds 80% of the total carbon emission. Steel, concrete and cement are the key sources of carbon emission. The contribution ratios of the three construction materials in carbon emission are 40%, 1.1% and 47% in one tunnel construction method and 39%, 29% and 26% in the other. By optimizing or improving the construction material production processes or increasing the proportion of clean energy in electric energy structure, the carbon emission factors in construction materials production and electric energy production can be reduced, to eventually reduce carbon emission significantly. 2023 Vol. 60 (3): 14-23 [Abstract] ( 213 ) [HTML 1KB] [ PDF 3109KB] ( 528 ) 24 Nonlinear Model for Segment Joint Stiffness Based on Deep Neural Network and Its Application YAN Pengfei CAI Yongchang ZHOU Long The beam-spring model calculation formula is concise and easy to use in numerical calculation, it can be used to effectively evaluate the jointing effect of lining segments, and it has been widely used for design of lining structure of shield tunnel. As an important parameter that represents the joint performance, the joint stiffness (particularly the flexural stiffness) selected will directly determine the calculation accuracy of the beam-spring model and it is very important for internal forces analysis of lining structure of shield tunnel. With the internal forces (bending moment and axial force) as the input features and the flexural stiffness of joint as the output, this paper offers a deep neural network model that can indicate the nonlinear feature of flexural stiffness of joint. Based on the joint fullscale test data and through forward propagation and back propagation algorithms training, the nonlinear mapping function between joint flexural stiffness and internal forces that has analytical form and that is universally applicable has been obtained. This overcomes the limitedness of fitting results of traditional method and solves the problem that it is difficult to obtain the expression for joint flexural stiffness in the entire internal forces space. This comes as a new approach for nonlinear prediction and uniform continuous expression of joint flexural stiffness based on joint full-scale test data. The comparison between the joint flexural stiffness value predicted by the nonlinear model based on deep neural network and the full-scale test data and the application of the method in calculation and analysis of full-ring lining structure have proven the correctness and effectiveness of this method 2023 Vol. 60 (3): 24-33 [Abstract] ( 231 ) [HTML 1KB] [ PDF 5522KB] ( 471 ) 34 Analysis of Stress Characteristics and Stability of Initial Support Arch of Tunnels with the Spatial Effect of Truss Structure Taken into Consideration SUN Yi By now, no standard has been established for structural design of initial support of tunnels. During actual construction, selection of the parameters of initial support arch mainly relies on previous construction experience,and the structural calculation often simplifies the arch as an ideal uniaxial member. In order to provide the theoretical basis for fine design of the initial support arch, the common structural forms of initial support arch are gathered in this paper, and the common geometric parameters of three-string and four-string lattice girder and section steel arch are presented. After the relation between crown settlement and surrounding rock pressure is established, the concept of support rigidity of initial support arch is proposed. With the restraining action of arch feet lock adequately considered, the hingeless arch model and two-hinged arch model under the action of uniform centripetal load have been built. The instability mechanism of initial support arch in the two models has been analyzed, and the method to determine the stability factor of hingeless arch and two-hinged arch has been given; it is believed that the critical load can be used as a criterion for determining the stability of arch system. On this basis, how the diagonal web member will affect the compressive stiffness and flexural stiffness of arch in the basic configuration of Pratt type and Warren type lattice girders has been analyzed. As the results suggest, compared with the ideal state, when the shear deformation of lattice unit is considered, the critical load of the support with lattice girder decreases. The mechanical structural model of steel reinforcement with "8"-shaped knot has been built, decompositional projection of the forces on the structure has been conducted, and the methods to calculate the axial compressive stiffness, flexural stiffness and shear stiffness of the crossed lattice unit of chord-free member has been put forth. After numerical simulation and calculation of engineering cases, it is believed that the analytic formula can be used to accurately calculate the destabilization load of support arch and the arch stiffness. The study results are helpful for scientifically understanding the bearing characteristics and stability of initial support of tunnel, and are valuable reference for selection and operation of initial support structure. 2023 Vol. 60 (3): 34-43 [Abstract] ( 156 ) [HTML 1KB] [ PDF 2492KB] ( 379 ) 44 Prediction and Analysis of Tail Seal Grease Consumption of Slurry Shield Machine Based on IPSO-ANN Time Series Model BAI Rongmin1 MA Yuyang2 LIU Sijin2 FANG Yong1 HE Chuan1 Accurately predicting consumption of tail seal grease is very important to tail seal, shield tunnelling safe? ty and cost control. Therefore, the K-fold cross-validation and ANN neural network have been used to improve the conventional particle swarm optimization algorithm, so as to allow the IPSO algorithm to automatically find the optimum neuron hyper-parameters of ANN neural network and build the IPSO-ANN time series model for the slurry shield tail seal grease consumption. In the Jinan Yellow River Tunnel project, based on the seal grease consumption of the east and west lines and the influencing factors that are obtained through double screening, the 3 strategies including hybrid training, east line separate training and west line separate training have been established that are used for model training, and the grease consumption in construction section have been predicted and analyzed. As the results suggest, the IPSO-ANN model is effective in finding the neural network model that has the optimum neuron hyper-parameters; under different training strategies, the average prediction accuracy of optimum model is above 80%, the prediction accuracy under the hybrid training strategy is 85.142%, and there is also good stability,so this model is useful for predicting tail seal grease consumption. 2023 Vol. 60 (3): 44-54 [Abstract] ( 204 ) [HTML 1KB] [ PDF 7317KB] ( 441 ) 55 Study on Selection of Highway Tunnel Renovation and Expansion Schemes Based on Triangular Fuzzy Number and GWO-ELM Model YE Lianchao1 HE Jiangling2 LI Ke3 QIU Zhixiong2 JIANG Xinghong3 Renovation and expansion of existing tunnels is still an important solution to the problem of inadequate traffic capacity of in-service tunnels resulting from increased traffic volume, but selection of tunnel renovation and expansion schemes is an issue of multi-attribute decision-making, where there is high level of fuzziness and uncertainty between the attributes. Therefore, in order to ensure science-based and rational selection of renovation and expansion schemes, a new tunnel renovation and expansion scheme selection model has been proposed. By summarizing the common schemes for domestic expressway tunnel renovation and expansion and analyzing the factors that affect renovation and expansion of expressway tunnels, the evaluation indicator system for selection of tunnel renovation schemes has been established. On the basis of the domestic tunnel renovation and expansion data from the recent 30 years, the GWO-ELM tunnel renovation and expansion scheme selection model based on triangular fuzzy number has been proposed. As the results suggest, optimizing the ELM model by using the GWO algorithm will allow the advantages of ELM, i.e. excellent generalization performance and quick learning speed, to be adequately exploited,thus significantly enhancing the accuracy of the renovation and expansion scheme selection model; the scheme selection efficiency of the GWO-ELM model combined with triangular fuzzy number is clearly superior to that of the ordinary GWO-ELM; this scheme selection model, characterized by excellent small sample processing capacity and high selection accuracy, is an efficient tunnel renovation and expansion scheme selection model. 2023 Vol. 60 (3): 55-64 [Abstract] ( 206 ) [HTML 1KB] [ PDF 4759KB] ( 332 ) 65 Suggestions on Revision of the Provisions for Calculating the Impact Force of Rockfall in Guidelines for Design of Highway Tunnel (JTG D70-2010) LI Liangpu1 YUAN Song1,2 LIAO Peiyuan1 WANG Xibao1 The impact force of rockfall, as the main accidental load, must be considered in the design for the open cut tunnel section and the open cut tunnel and shed tunnel sections specifically designed to prevent high-level collapse and rockfall. Due to the high research difficulty and complexity, the impact force of rockfall has always been a difficult problem to be solved in the industry, which determines that the current design of open cut tunnels and shed tunnels still relies mainly on experience analogy, supplemented by structural calculation and analysis. There are some problems in the current Guidelines for Design of Highway Tunnel (JTG D70-2010) that have not been discovered and corrected in a timely manner for the calculation of impact force of rockfall. This has led many scholars and designers in China to believe that the calculation results are severely distorted, resulting in small guiding significance of the Guidelines. In this paper, the abovementioned problems are corrected. Meanwhile, the issues not clearly specified in the Guidelines are analyzed and discussed, such as the difference between the contact force and the response force while the rockfall impacting the structure, the scope of action of the rockfall impact load, the effective length of the structure and the most unfavorable fortification object, and the corresponding modification suggestions are proposed. It is suggested that when the Guidelines is revised in the next edition, it should be more perfect, so as to better guide the calculation and design of the open cut tunnel and shed tunnel structures. 2023 Vol. 60 (3): 65-73 [Abstract] ( 217 ) [HTML 1KB] [ PDF 4023KB] ( 452 ) 74 Study on Type Selection and Parameter Optimization of the Shield Cutters Used for Cutting Sludge Stratum Containing Prefabricated Vertical Drains WANG Dahai1 HU Yanfeng2 The prefabricated vertical drains are widely used for reinforcing soft soil foundation, but its high tough? ness, corrosion resistance and non-degradability can be very bothering to later shield tunnelling in the stratum. To solve this problem, the simulation model for different cutters that are used to cut the sludge stratum reinforced by prefabricated vertical drains has been created by using the ABAQUS finite element analysis software, and the cutting results of different cutters have been compared from the aspects such as cutting force and variation characteristics.The analysis reveals how the cutting force of sharp-edged tearing cutter will be affected by the factors including cutter width, cutting edge height, cutting speed and cutter penetration. The study shows that the scraper is suitable for sludge stratum, while the sharp-edged tearing cutter is suitable for cutting prefabricated vertical drain and the width of the sharp-edged tearing cutter should not be less than 50 mm, but the regular 70 mm width will meet the construction requirements; the cutting edge height should preferably be 40 mm or 50 mm; the faster the cutterhead ro? tates, the better the cutting performance, and the rotating speed should not be less than 400 mm/s; the cutter penetration must be strictly controlled, to protect the cutter from damage caused by excessive or unstable force. For the sludge stratum containing prefabricated vertical drains, the combined cutters composed of sharp-edged tearing cutter and scraper is helpful for shield tunnelling. 2023 Vol. 60 (3): 74-80 [Abstract] ( 140 ) [HTML 1KB] [ PDF 2656KB] ( 487 ) 81 Differences in Mechanical Responses of Granite and Limestone when Cut by TBM Disc Cutters WANG Lichuan1,2 FU Boyi2 ZHANG Huijian2 JI Guodong1 GENG Qi3 WANG Zhengzheng4 In order to reveal the differences in mechanical responses of granite and limestone when penetrated by TBM, the double disc cutters rock breaking mechanism and the influencing factors have been investigated by using the methods including measurement of mechanical parameters of standard rock specimen, ABAQUS-SPH numerical simulation and field measurement. As the results suggest, the ABAQUS-SPH numerical simulation method is effective in simulating rock deformation and failure state during rock breaking by disc cutters; the torque of the disc cutter is sensitive to the cutting sequence, while the disc cutter thrust is sensitive to the rock strength. When rock strength increases, the disc cutter needs much more thrust to cut to the same level. Under the calculated parameters in this study, the rock breaking efficiency of the disc cutter when penetrating limestone stratum is higher than the efficiency when penetrating granite stratum, and the rock ridge width between cutters is in direct proportion to rock strength. 2023 Vol. 60 (3): 81-89 [Abstract] ( 167 ) [HTML 1KB] [ PDF 5813KB] ( 350 ) 90 Study on the Impact of Different Construction Timings of Internal Structure on the Stress of Segmental Lining of the Shield Tunnel with an Super-large Section HU Zhenyu1 FENG Kun1 GUO Wenqi1 PENG Changsheng2 LI Jiaoyang2 In the He'ao Tunnel project which is under construction, finite element method (FEM) is utilized to build a 3D refined numerical calculation model for segments and internal structure, and the impact of construction timing of internal structure on the stress performance of segmental lining of the shield tunnel with a super-large cross section is studied through the analysis of the stress and deformation of segments and internal structure at different construction timings of internal structure. The results show that both the transverse stiffness of segment rings and the proportion of segment stress shared by the internal structure would be raised if the internal structure construction started in advance. For example, if the construction timing is advanced from the time when ovality is 5‰ to the time when ovality is 3‰, the extreme values of the deformation of segment and internal structure will be reduced by 28.47% and 32.83% respectively, the extreme values of the stress of segment and its rebars will decrease by 50.0% and 14.4%, and the extreme values of the stress of internal structure and its rebars separately will increase by 70.37% and 19.55%; the construction timing of internal structure has no impact on the deformation and stress distribution law of segment ring and internal structure , but if the internal structure is constructed in advance, the stress of segments and rebars will be distributed more evenly; the internal structure will have a relatively strong ability to suppress the horizontal deformation of segment rings. Taking the case where the construction timing is the time when ovality is 3‰ as an example, the vertical displacement of segments continue to increase by about 19.0% after the construction of internal structure, while the horizontal displacement increases by 0.36% only, and the deformation shape changes from "horizontal duck egg shape" to "butterfly shape" . 2023 Vol. 60 (3): 90-101 [Abstract] ( 218 ) [HTML 1KB] [ PDF 7859KB] ( 384 ) 102 Study on the Cracking Mechanism of Subsea Shield Tunnel Segments under the Dual Mechanical Action of Loading and Corrosive Expansion QIAN Yuan1 XU Chong2 LIU Xiaorui2 HUANG Meng3 The cracking caused by the corrosive expansion of shield tunnel segments in the marine corrosion envi? ronment is a major threat affecting the safe serviceability of a tunnel. Attention should be paid to the combined action of lining stress arising out of water and soil pressure and additional stress arising out of rebar corrosion. Based on the extended finite element method (XFEM), a corrosive-expansion-induced cracking analysis model for the subsea shield tunnel was built to reflect this dual stress action, and the corrosive expansion-induced cracking behaviors and mechanical mechanism of lining rings during its service were studied. The results showed that the corrosive expansion-induced cracking behaviors in different positions of lining rings were significantly affected by the original lining stress of segments; two haunches on the outer ring and the crown and arch bottom on the inner ring were located in the tensile stress concentration zone of lining rings, and the tensile stress caused by water and soil pressure is the major factor affecting lining cracking, while the effect of corrosive expansion was relatively small, and these cracks were characterized by early cracking, rapid extension and cracking perpendicular to the protection layer; two haunches on the inner ring and the crown and arch bottom on the outer ring were the compressive stress concentration zone of lining rings, and its cracking arising out of the relatively high compressive strength of concrete was mainly dependent on the tensile stress caused by corrosive expansion of rebars. Rebar corrosion had to last long enough to transform the surrounding concrete from being compressed to being tensioned and finally cause cracking, and these cracks were characterized by late cracking, slow extension and cracking parallel to the protective layer; arch shoulder and foot were in the status of stress transition, and cracks obliquely intersected the protective layer. 2023 Vol. 60 (3): 102-111 [Abstract] ( 188 ) [HTML 1KB] [ PDF 4482KB] ( 321 ) 112 Discrete Element Numerical Simulation Study on Shear Characteristics of Tunnel Systematic Bolts Based on Shear Boundary ZHAO Dongping1,2 ZHANG Bohao2 LI Hua3 ZHAO Xiaoyu3 By using the block discrete element numerical simulation method and creating the boundary conditions of bolt shearing, the numerical simulation study on the sectional distribution characteristics and evolution law of shear of tunnel systematic bolts has been conducted, and how the factors such as surrounding rock fracture degree and bolts layout pattern will affect the bolt shear has been investigated. The study results are stated as follows: (1) The shear of the tunnel systematic bolts and joint shear displacement are in positive correlation, and the shearing effect of bolt happens in broken rock mass and is negligible in intact rock mass; (2) The bolt shear is always less than the axial force at the same position, but the maximum shear-axial force ratio is close to 75%; (3) In the initial stage of bolt installation, the bolt shear will differ considerably due to the installation position and the distance between bolt and inner contour surface of tunnel, and the bolt shear peak in the initial stage of installation may be higher than the long-term stable value; (4) Greater broken rock volume or greater breaking range in the broken rock mass means greater bolt shear; (5) Longer bolts are more susceptible to shear, and densely placed bolts can help reduce the shear sustained by the systematic bolts. 2023 Vol. 60 (3): 112-122 [Abstract] ( 150 ) [HTML 1KB] [ PDF 7370KB] ( 378 ) 123 Study on Forces on Pipe Umbrella Support in the Whole Process of Tunnel Excavation JI Yunpeng1,2 FANG Lingguo3 TANG Haotian4 ZHANG Xingli1,2 WANG Xiangjin1,2 BAI Yuntian1,2 In order to investigate the mechanical behaviors of the pipe umbrella support system in the tunnel at the Hutan New Area Station of Dalian Metro Line 5, finite element simulation of the tunnel pipe umbrella support system has been conducted by using the Plaxis software, the mechanical behaviors of the pipe umbrella support in the whole process of tunnel excavation have been analyzed, the results of finite element simulation have been compared against the ground settlement and crown settlement observed on site, and simulation analysis for optimization of the pipe umbrella support parameters has been conducted. The calculation results suggest that in the whole process of tunnel excavation, the pipe umbrella deformation and stress show the stepped or wave-like variation pattern. Through comparative analysis on the changed design parameters of pipe umbrella, it is concluded that the pipe umbrella forces are significantly affected by soil stratum load, the axial force of pipe umbrella is mainly affected by the circumferential spacing of pipe umbrella, and also the bending moment and shear force are significantly affected by the pipe diam? eter. For subway tunnel construction, use of pipe umbrella support will ensure the works proceed successfully 2023 Vol. 60 (3): 123-138 [Abstract] ( 185 ) [HTML 1KB] [ PDF 12153KB] ( 446 ) 139 Numerical Simulation Study on Water Resistance of Gasket with Consideration of Compression-Joint Staggering-External Hydraulic Pressure XUE Guangqiao1 YU Xiongbing3 XIAO Mingqing1,2 ZHANG Chaoyong3,4 HE Yingdao1,2 During erection of shield tunnel segments, gasket experiences the time-variant scenario of "compression before joint staggering". The ANSYS is used to build the three-dimensional finite element model of gasket and groove, and the loading mode of "compression before joint staggering" that more closely resembles the construction process characteristics is used to conduct numerical simulation study on water resistance and to conduct comparative analysis of the conditions without consideration of the compression-joint staggering time-variant sequence. As the results suggest, the water resistance of the gasket with "compression before joint staggering" is superior to that of the gasket with "joint staggering before compression"; compression will create great friction between the gasket contact surfaces, so upon joint staggering of the gasket, the gasket contact surfaces will not be completely staggered, and the overall deformation pattern is in one-sided inclination; with hydraulic pressure considered, the water resistance of the gasket with "compression before joint staggering" is better than that in the condition without hydraulic pressure, which indicates that hydraulic pressure further compresses the gasket and thus increases the surface contact stress and enhances the water resistance. 2023 Vol. 60 (3): 139-145 [Abstract] ( 178 ) [HTML 1KB] [ PDF 4206KB] ( 427 ) 146 Study on Dynamic Response in Cut Blasting in Closely-spaced Overlapping Tunnels YUAN Ran1 LI Junhui1 CHU Zeyuan2 ZHANG Rui3 LUO Chunyu4 In the study on blasting excavation of the Donghuashan Tunnel in Bazhong, Sichuan, the velocity field and stress field distribution characteristics of lining structure of existing tunnel have been analyzed by using the dynamic finite element software LS-DYNA, the decoupled charging method and the fluid-structure interaction calculation method, and the correctness of the calculation result has been verified by using the monitoring data. On this basis and in view of how the angle of cut hole will affect the dynamic response in blasting excavation of tunnel, 6 sets of cases have been established in the range of 15°~75°, to investigate the law of dynamic response of existing tunnel lining. As the results suggest, the vertical vibration velocity of existing tunnel lining is the greatest of all vibration velocities, and the vertical peak vibration velocity is used to represent the maximum structural vibration characteristic; the maximum vertical vibration velocity of existing tunnel occurs behind the blasting face, and the maximum vertical vibration velocity of the least favorable cross-section appears at the arch bottom; the maximum principal stress peak is mainly present at the arch bottom and the left and right arch feet, and the maximum tensile stress appears at the left arch foot; greater included angle between cut hole and tunnel face means greater vibration velocity and greater maximum principal stress peak generated by the blasting, and there is a clear linear relation between the two parameters. The monitoring points should preferably be set at the arch bottom and foot of the lining behind the blasting face, and the vibration response can be abated by decreasing the angle of cut hole. Based on the stratum conditions and spatial characteristics of the tunnel of interest, the vibration velocity safety threshold of existing tunnel lining is 18.17 cm/s. 2023 Vol. 60 (3): 146-155 [Abstract] ( 162 ) [HTML 1KB] [ PDF 4495KB] ( 425 ) 156 Study on Large Deformation Law of Soft Rock Tunnel in Red Bed in Central Yunnan ZHANG Xuejun1 NIE Qiqiang2 GONG Yuanjiang3 Problems including poor stability of surrounding rock, rock softening in water and large deformation of soft rock are encountered during the construction of Fenghuangshan tunnel in No.6 bid section of Chuxiong section of Water Diversion Project in Central Yunnan. In this paper, firstly, the physical and mechanical characteristics of soft rock in the large deformation area are obtained by carrying out the indoor mechanical test on typical soft rock samples in the area, and the deformation characteristics are known by analyzing the failure of the tested soft rock;secondly, FLAC 3D numerical simulation software is used to calculate the stress and strain changes of the tunnel in the large deformation section, and the characteristics of the large deformation of the Fenghuangshan tunnel are mastered; finally, the FLAC 3D simulation results are compared and verified with the field monitoring data, and the comparison results are within the allowable range of error, proving the accuracy of the numerical simulation. 2023 Vol. 60 (3): 156-163 [Abstract] ( 180 ) [HTML 1KB] [ PDF 4932KB] ( 405 ) 164 Model Experimental Study on Interaction Characteristics of Rock and Structure in Weak Rock Tunnels WANG Xiuling1,2 In order to reveal the interaction between ground and the support in weak rock tunnels, the Shijiashan Tunnel, which is the key project for China's first tourism rail transit project, is investigated, and a test platform that can control ground deformation is developed. The ground deformation is used to represent the installation timing of support, and the geomechanical model test is conducted. The study results suggest: (1) The installation timing of support will significantly affect the dynamic evolution and distribution of radial compression and tangential stress of soft ground. (2) Under different controlled deformations, the radial stress release of ground always experiences three stages of development as deformation increases. (3) Under the same deformation, the radial stress response characteristics of different parts of the tunnel differ noticeably, and as controlled deformation increases, the response speed of different parts change obviously. (4) Increase of controlled deformation causes the ground failure response speed of different parts of tunnel to be faster, the core area of failure is shifted, and the non-uniformity of tangential stress distribution increases significantly. (5) The structural support is appreciably affected by the installation timing of support, and the radial stress release of shallow ground is controlled by the preliminary minor deformation. When deformation reaches a certain threshold, stress release becomes unobvious, while the disturbance depth expands, the stress of deep ground is released, and the disturbance zone and failure zone of ground expand faster. 2023 Vol. 60 (3): 164-174 [Abstract] ( 209 ) [HTML 1KB] [ PDF 7038KB] ( 391 ) 175 Experimental Study on Filter Cake Formation in Slurry Shield Tunnelling in Cobble-gravel Stratum Using Slurries with Various Properties LI Hui1 LIU Hongzhi1 WANG Shiyu2, 3 WANG Yunzhi2, 3 MIN Fanlu2, 3 Given the problem of filter cake formation of the slurry shield that passes through a highly permeable cobble-gravel stratum in the Tuan-Jiu Project Phase II under the South-to-North Water Diversion Project in Beijing,the slurries with different densities and different sand quantities are prepared to conduct the filter cake formation test,and the filter cake formation effect is analyzed from aspects such as slurry seepage discharge and permeability coefficient of filter cake. As the results show, in a highly permeable stratum with coefficient of permeability of 10-1 cm/s magnitude, the bentonite-clay mixed slurry with density <1.25 g/cm3 is difficult for filter cake formation, but the slurry with density of 1.3 g/ cm3 can form a slurry skin + permeation zone type filter cake. If the bentonite-clay mixed slurry with density of 1.15 g/cm3 is given a proper amount of sand, it will form a slurry skin + permeation zone type filter cake, and the seepage discharge and filter cake formation time are noticeably decreased as compared with the slurry without sand and with the same density. As more sand is added, the seepage discharge of slurry decreases slightly, and the void ratio and permeability coefficient of the formed filter cake show also the trend of decreasing.When the sand content is 5%, the permeability coefficient of the formed filter cake reaches the 10-8 cm/s magnitude. 2023 Vol. 60 (3): 175-181 [Abstract] ( 159 ) [HTML 1KB] [ PDF 3313KB] ( 409 ) 182 Study on Grout Test for Wall Grouting of the Shield Built of Waste Silty Soil and Sand with High Silt Content FANG Zhongqiang1,2 YUAN Rui3 SUN Tongli1,2 WANG Dengfeng3 JIANG Suyu4, During slurry shield construction, a large quantity of waste mud and sand will be generated inevitably, and improper disposal of such material will impose negative impacts on the environment and also cause a waste of resources. In the Jiangyin Jingjiang Yangtze River Tunnel Project, waste silty soil and sand are used to replace commercial mortar in various proportions to prepare the grout used for wall grouting, so as to investigate how replacement ratios will affect the grout performance, and the phase composition and microstructure are analyzed in order to analyze how waste silty soil and sand will affect the grout performance. As the results suggest, addition of waste silty soil and sand will shorten the setting time of grout and enhance the stability of grout, but will cause the fluidity and early age strength of grout to decrease by a small extent. However, the grout performance can still meet the engineering requirements; when the replacement ratio is 40%, the grout fluidity is 26.8 cm, the setting time 11.5 h and bleeding rate 3.4%, which meet the grouting requirements, so this replacement ratio is the optimum value; after addition of waste silty soil and sand, the fly ash in the grout that does not completely participate in the reaction increases, the content of the reticular C-S-H (hydrated calcium silicate) gel decreases, and the extent of hydration reaction decreases. 2023 Vol. 60 (3): 182-188 [Abstract] ( 153 ) [HTML 1KB] [ PDF 3949KB] ( 404 ) 189 Shear Failure Mechanism of F-type Socket-and-Spigot Joint in Rectangular Pipe Jacking Tunnels XU Youjun1,2,3 KANG Jiawang1 ZHANG Chao1,2,3 HUANG Zhengdong1 ZHANG Xu1,2,3 The joint is the weakest link of the rectangular pipe jacking tunnel, which is very sensitive to the uneven settlement of the foundation, and is prone to shear dislocation and deformation between pipe joints. Taking the Ftype socket-and-spigot joint as the research object, the indoor test and ABAQUS finite element were used to analyze the macroscopic failure phenomenon, the shear deformation mechanism of the joint was obtained, and the tunnel deformation control standard was established. The results show that the shear failure characteristics of the pipe jacking tunnel are divided into three stages: gap closure, shear strengthening and yield failure, and the shear stiffness in the second stage is the largest; when shear failure occurs, the steel ferrule and concrete are prone to stress concentration at the chamfered position; proper addition of longitudinal connectors can improve the stability and shear stiffness of flexible joints; the steel ferrule begins to yield at a staggered volume of 12 mm, and the plastic failure begins to occur when the staggered volume is 27 mm. 2023 Vol. 60 (3): 189-198 [Abstract] ( 154 ) [HTML 1KB] [ PDF 5520KB] ( 312 ) 199 Simulation Analysis of the Forces on Lining Structure of Shield Tunnels and Fire Resistance Measures during Fire XIAO Mingqing1,2 YANG Wenqian3 FENG Kun3 JIAO Qizhu1 MAO Sheng1 WANG Yunchao3 As for the Jintang Subsea Tunnel on Ningbo-Zhoushan Railway, the numerical simulation method is used to analyze the stress, deformation and deterioration of shield tunnel lining structure induced by fire under the RABT standard heating curve, and to investigate the fire resistance of segmental lining structure of large-diameter shield tunnel under high temperature of fire and the fire resistance measures. As the results suggest, after 120 min of exposure to fire under the RABT heating curve, the fire heated surface of concrete lining reaches 1,119 ℃, so the lining structure cannot meet the fireproofing design requirements; the concrete lining starts deterioration after 5.3 min of exposure to fire, the failure zone continues expanding as the duration of fire increases, and when the fire stops, the maximum deterioration depth is greater than 12 cm; in addition, when the fire stops, the clearance convergence of the tunnel in both vertical and horizontal directions decreases as compared with that before the fire, and the absolute value of the decrease is 11.5 mm and 0.12 mm respectively; the 3 techniques, i.e. installing concrete refractory layer on segments, installing fire board and applying fire-resistant coating, will effectively enhance the fire resistance of the lining structure, but with comprehensive consideration of the factors such as suitability in practical engineering,it is recommended to use the C40 concrete refractory layer with ≥8 cm thickness or the fire-resistant coating with thermal conductivity <0.15 W/(m·K). 2023 Vol. 60 (3): 199-207 [Abstract] ( 194 ) [HTML 1KB] [ PDF 4890KB] ( 365 ) 208 Method for Comprehensive Evaluation of Longitudinal Crack Defect of Lining of Single-track Railway Tunnels YUAN Hongyun1,2 CHEN Liwei2 LIU Zhiqiang2 Through finite element model calculation, the way the length and depth of cracks in railway tunnel lining impact structural safety has been analyzed, and structural safety sensitivity analysis has been conducted through the orthogonal test. On this basis, the comprehensive evaluation model for impact of lining cracks has been established that is based on the 3 characteristic parameters including length, width and depth (ratio), thus it is possible to conduct quantitative evaluation of how longitudinal crack defect of single-track railway tunnel lining impacts lining structure safety and to create the reference table for normative evaluation. 2023 Vol. 60 (3): 208-216 [Abstract] ( 230 ) [HTML 1KB] [ PDF 4023KB] ( 410 ) 217 Analysis of Temporal and Spatial Variation Law of Crystalline Materials and Water Environment and Crystallization Path of the Tunnel Drainage System in Calcium-bearing Surrounding Rocks LIU Yuyang1 XI Longlong1 LAI Hongpeng2 ZHAO Yongbin3 SUN Weixing3 JIA Neng1 By testing the samples collected from the crystalline materials and water environment of 7 tunnels in cal? cium-bearing surrounding rocks, the temporal and spatial variation law and characteristics of crystalline minerals,water quality and ion concentration have been analyzed, the drainage crystallization path model has been built, the calcium source and carbon source of crystallization have been identified, and the suggestions for prevention and control of the problems are offered. As the results suggest, depending on their forms, the crystalline materials in the drainage system of mountain tunnels can be classified into soft flocculent material, powdery blocky material and hard stony material. The three types of materials have different forms and hardness values and their generative processes are consistent. The forms of crystalline materials are useful in selecting the methods for solving crystallization. The water quality parameters and ion concentration show clearly uniform spatial pattern; the shotcrete initial support has the most obvious impact on the water environment; after water permeating through shotcrete initial support, the pH value, total dissolved solids (TDS) , Ca2+, Na+, K+ and CO32- concentrations in the water increase signifi? cantly, while the HCO3- concentration decreases significantly; the increase and decrease of Ca2+ concentration will reveal the current condition and history of initial support cracking, SO42- is not involved in the crystallization related reactions, and its concentration is helpful for determining whether the surrounding rock water environment has changed. In the crystallization path, the carbon source of crystalline materials is from biological residue, respiration of plant root system and dissolution of carbonate, while the calcium source is from calcium dissolution and precipitation of calcium-bearing surrounding rock and the dissolution of hydration products of initial support concrete. 2023 Vol. 60 (3): 217-226 [Abstract] ( 153 ) [HTML 1KB] [ PDF 4508KB] ( 406 ) 227 Study on Key Construction Technology for Cross Passages in Large-diameter Shield Tunnels in Water-bearing Silty Fine Sand Stratum：A Case Study of the Karnaphuli River Tunnel Project in Bangladesh HAN Xiaoming1,2 HE Yuan1,2 ZHANG Feilei2,3,4 The No. 2 cross passage of the Karnaphuli River Tunnel Project in Bangladesh is located in a water-bear? ing silty fine sand stratum below the river bottom center. This cross passage is characterized by large excavation diameter and high water and soil pressure. In order to ensure safe construction of the cross passage in the middle of the river when there is shortage of overseas emergency rescue resources, comprehensive technical measures have been proposed from aspects such as freezing hole layout and drilling, temporary support structure of tunnel, excavation and structure construction: (1) The freezing holes are arranged in inner and outer circles, with supporting features at the bottom; (2) Freezing hole drilling process is conducted by means of step-by-step boring, slow pipe advancing and fast plugging by reducing tapered joint; (3) The steel support structure of ring beam in the main tunnel is superseded by the reinforced annular frame beam at the tunnel portal; (4) The construction process is conducted by means of zoned works, fast pilot tunnel construction, excavation by bench-cut method, expanded excavation opposite to free face and excavation-and-support method; (5) The effects of frost heave and thaw settlement are reduced by fast freezing, natural thawing and track grouting. At last, the major risk points are predicted and analyzed,and the preventive measures are prepared accordingly. As proven by the data from freezing hole temperature monitoring and main tunnel lining structure deformation monitoring, this technology will ensure successful construction of cross passage of large-diameter shield tunnel. Such successful construction experience can be valuable reference in other similar projects at home and abroad. 2023 Vol. 60 (3): 227-235 [Abstract] ( 257 ) [HTML 1KB] [ PDF 4527KB] ( 374 ) 236 Study on Technical Solutions to the Problems in Freezing Method Design and Construction of Subway Cross Passages in Sandy Cobble Stratum with High Flow Rate and High Permeability ZHANG Ming WAN Bo Attributed to construction of the South-to-North Water Diversion Project, the groundwater supply in Bei? jing area has been replenished amply and consequently the groundwater level has risen sharply, which makes rail transit system construction more difficult. After practical design and construction of the cross passages using freezing method in a running tunnel section of the Metro Line 12, the supporting measures for freezing method construction in sandy cobble stratum with high flow rate and high permeability have been proposed. Besides, the cause of freezing wall failing to be closured has been analyzed, the weak parts of freezing wall have been identified and thus the engineering solutions have been proposed. Then the technical feasibility of the freezing method used in sandy cobble stratum with high flow rate and high permeability is analyzed. The results will be used for reference in engineering design and construction of the similar projects that use the freezing method. 2023 Vol. 60 (3): 236-241 [Abstract] ( 156 ) [HTML 1KB] [ PDF 1990KB] ( 569 ) 242 Study on Large Deformation Control Method and Structural Mechanical Characteristics of Shanyang Tunnel in Soft Rocks TIAN Baohua1 ZHAO Yongming1 WU Xingzhou1 ZHANG Biao1，2 GAO Song1 In order to effectively control the large deformation of soft rock in the thin-bedded broken shale section in the Shanyang Tunnel on Dali-Ruili Railway, a construction method has been proposed that is comprised of surrounding rock pre-reinforcement by curtain grouting, advance middle pipe umbrella and advance water exploring and pressure relief holes and the three-bench mechanical excavation. The side wall excavation curvature is increased to change the U-shaped excavation section to egg-shaped excavation section, the deformation allowance increases from 10 cm to 50 cm, and the initial support structure changes from the I25 single-layer steel rib with 1 m spacing to the double-layer HW175 steel rib with 0.6 m spacing. All these measures have solved the challenging problems such as steel rib distortion and cross section intrusion. According to force monitoring on the support structure on site, the forces on some of the steel ribs of double-layer initial support exceed their yield strength, mainly because the support structure sustains excessive force while the surrounding rock load is not adequately released. It is recommended to release a part of the surrounding rock pressure before construction of the second layer of initial support. 2023 Vol. 60 (3): 242-251 [Abstract] ( 173 ) [HTML 1KB] [ PDF 6621KB] ( 436 ) 252 Study on Two-bench Construction Method with Rapid Ring Closure under the Condition of Large Soft Rock Deformation in Yuelongmen Tunnel LIU Guoqiang Given the large deformation of soft rock with high ground stress in the Yuelongmen Tunnel on the newly built Chengdu-Lanzhou Railway, the concept of "active control" has been proposed. In addition to the advantage of rapid mechanized construction, the control measures including "optimized contour, two-layer support, step-by-step reservation, anchor-support combination, surrounding rock consolidation and rapid closure" are employed, where emphasis is put on the process control of deformation development. The key technology of "two-bench (inclusive of tunnel bottom) construction with short bench rapid ring closure" has been developed, to eventually achieve effective control of large deformation in soft rock. 2023 Vol. 60 (3): 252-258 [Abstract] ( 152 ) [HTML 1KB] [ PDF 4899KB] ( 347 ) 259 Study on the Construction Equipment Configuration Scheme for Tunnelling under High Altitude, Low Oxygen Content and Low Atmospheric Pressure Conditions WANG Liuxun In view of the fact that the tunnel construction in high altitude areas is affected by the climate environ? ment of low temperature, low atmospheric pressure and low oxygen content, which leads to the overall efficiency shortage or waste of construction machinery and equipment configuration, this paper proposes a relatively complete,reasonable and scientific construction equipment configuration scheme based on the high-altitude ultra-long highway tunnel, the Que′ershan Tunnel on National Highway 317. Specifically, it includes eight main equipment configurations: drilling and blasting, excavation and transportation, air supply, ventilation, water supply, power supply,heating and oxygen supply. Based on the configuration of construction equipment for the Que′ershan Tunnel, a fully-electrified equipment configuration plan for high-altitude tunnel drilling and blasting construction is further studied and proposed, and relevant prospects are made from the aspects of "oil to electricity" technology, construction organization and management, and battery technology related to electric engineering equipment. 2023 Vol. 60 (3): 259-265 [Abstract] ( 172 ) [HTML 1KB] [ PDF 1620KB] ( 403 ) 266 Comparison and Selection of Construction Schemes for the Boom-type Roadheader in Small-section Tunnels LIU Wanlin1 SHANG Mingming2 WANG Quansheng2 WANG Donghong2 WEN Shiyu1 In order to solve the problems caused by the limited operation space inside the small-section tunnel due to the influence of section size in actual construction, such as multiple process intersections, large mutual interference,periodic cycling of drilling and mucking on the same working face, and the inability to use efficient large-scale mechanical equipment in construction, this paper first puts forward three mechanized construction schemes based on the Longshushan Small-section Tunnel Project in Honghe section of the water diversion project in Central Yunnan,compares and analyzes the construction machinery, construction methods, construction progress and other aspects used in each scheme, and determines the final construction supporting scheme, in which the CTR300S boom-type roadheader, developed by China Railway Engineering Equipment Group Co., Ltd. specially for small-section hydraulic tunnels, is used combined with manual supporting operation. A technical application experimental study was conducted on the selected construction supporting plan after theoretical analysis. The results showed that: (1) the stability of Grade Ⅳ~Ⅴ surrounding rocks is poor, mainly composed of slate, fine sandstone and limestone lithology. Under rich groundwater test cases, the working efficiency of CTR300S boom-type roadheader can reach 20~40 m3/h, and the estimated monthly excavation advance rate can exceed 150 m, achieving the expected progress effect; (2)it is feasible to provide a working platform for installation of arches, shotcrete and other processes at the cutting part of the roadheader for full-section excavation of small-section tunnels. 2023 Vol. 60 (3): 266-273 [Abstract] ( 164 ) [HTML 1KB] [ PDF 4398KB] ( 462 ) 274 SUMO-based Simulation and Evaluation of Traffic Organization Scheme for Yuelongmen Tunnel ZHOU Baochun1,2 A large number of different vehicles such as muck trucks and supply vehicles are used during the con? struction of the tunnel. Therefore, analyzing the traffic characteristics of vehicles in the tunnel and implementing reasonable traffic organization scheme can improve transportation efficiency and operation level. In this paper, in order to evaluate the traffic organization scheme for the Yuelongmen Tunnel, the simulated traffic section of the No. 3 inclined shaft work area of the Yuelongmen Tunnel is built by using the SUMO simulation method as well as setting different sections and operation levels. The running conditions of vehicles in the tunnel under different organization schemes are obtained from two aspects, i.e., operation time and fuel consumption, emission. On this basis, sensitivity analysis of vehicle speed is performed. The results show that increasing the number of sections and appropriately increasing vehicle speed can reduce the vehicle running time and fuel consumption, emissions in the tunnel, thereby improving the tunnel construction efficiency and traffic level. 2023 Vol. 60 (3): 274-281 [Abstract] ( 189 ) [HTML 1KB] [ PDF 127268KB] ( 391 )

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