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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2024 Vol.61 Issue.1 Published 2024-02-25 1 Digital Tunnel Liu Xuezeng1,2,3 Yang Zishuo1 Ding Shuang2,3 Fang Maoliu1 This paper gives detailed explanation as to the essentials and characteristics of digital tunnel and the reality of digital tunnel technology. Based on unified coding rule and multi-source data processing technology, digital tunnel technology is intended to realize digitization of the engineering data during survey, design, construction, operation and maintenance, build the digital tunnel model, seamlessly integrate the data of the 3 stages including design, construction and operation & maintenance, and establish the business management mode based on data and models.Based on digitization of engineering data, borne by models and through the means of parametric modeling and data inversion, this technology adequately reveals the interconnection between various engineering data, in order to guide the design, construction and maintenance decisions regarding tunnel and comprehensive application of data, render accurate data for construction, operation and management of tunnel projects, provide efficient comprehensive information analysis service, and achieve mutual exchange of information in the whole life cycle 2024 Vol. 61 (1): 1-15 [Abstract] ( 55 ) [HTML 1KB] [ PDF 8176KB] ( 635 ) 16 Current Situation and Outlook of Research into Subaqueous Shield Tunnel Construction and O&M Technologies BAO Xiaohua1,2,3 YUAN Huaicen1,2,3 CHEN Xiangsheng1,2,3 SHEN Jun1,2,3 GUO Jianbo4 With rapid development of subaqueous tunnel construction technologies of China, more and more sub? aqueous shield tunnels with long distance, large diameter, high hydraulic pressure and complex geological conditions will be built, and construction of such tunnels will be confronted with more complex geological conditions and more stringent technical standards. To ensure safety of subaqueous shield tunnels in their full life cycle, this paper expounds the current development of subaqueous shield tunnels and the challenges in their development, and offers a review of the existing technologies from the two aspects including construction and O&M of subaqueous tunnels.In terms of construction, this paper offers a review and outlook from 3 perspectives including shield machine optimization and tunnelling parameters control technology, subaqueous shield tunnel waterproofing technology and subaqueous shield tunnel seismic design. The current development of shield tunnelling control technology is presented,the causes of water seepage in construction of shield tunnel and the existing waterproofing technologies are analyzed,and the currently available seismic design methods for shield tunnel are explained. In terms of O&M, this paper offers a review and outlook from 3 perspectives including technology for long-term durability monitoring of subaqueous shield tunnel, structural nondestructive testing technology for subaqueous shield tunnel and intelligent operation and maintenance system for subaqueous shield tunnel. Long-term monitoring of structural durability is realized by using durability sensors. The tunnel structure testing technologies are explained, including the lining apparent quality testing technology and concealed structural defect testing technology, and the approaches to achieving safety management and efficient monitoring of operation of tunnels are explained by analyzing the completed intelligent operation and maintenance systems. The key technologies for construction and O&M of subaqueous shield tunnel are comprehensively analyzed herein, in the hope of finding more reliable and efficient solutions for maintaining safety of subaqueous shield tunnel in its full life cycle. 2024 Vol. 61 (1): 16-35 [Abstract] ( 47 ) [HTML 1KB] [ PDF 12325KB] ( 376 ) 36 Progress and Outlook of the Study on Blast Hole Optimization and Control Technologies for Tunnel Smooth Blasting LI Jinhang1 SONG Zhanping1, 2 YANG Pengtao3 PAN Hongwei1, 2 TIAN Xiaoxu1, 2 The New Austrian Tunnelling Method (NATM) is the mainstream method for the tunnel works in China, and smooth blasting as a key part of NATM has been widely applied. Under certain special geological conditions,many factors that affect smooth blasting will result in poor result of smooth blasting and unsafe vibration velocity of blasting. Given this problem, the current situation and the results of the research into the blast hole optimization and control technologies for smooth blasting have been reviewed and summarized. Then the shortcomings of the current research are analyzed, i.e. the blast hole form and parameters are selected without any uniform standard, so it is necessary to conduct further research from the theoretical perspective. The control technology will optimize the result of smooth blasting, but there is no quantitative standard for selecting the charge structure, there is no quantitative method for selecting the delay time of detonation network, and there has been no study on combined application of multiple optimization technologies for intelligent blasting. At last, this paper offers an outlook on the progress of blast hole optimization and blasting control technologies for tunnel smooth blasting, and notes that standardization of blast hole design, theorization of control technology and intelligentization of blasting technology will be priorities in the future research. 2024 Vol. 61 (1): 36-47 [Abstract] ( 87 ) [HTML 1KB] [ PDF 4414KB] ( 295 ) 48 Study on Correction of Surrounding Rock Classification for Single-tube Four-lane Highway Tunnel Based on the Failure Characteristics of Surrounding Rock QU Jianrong1 JING Yawen2 REN Zhaodan1 XIONG Ying2 CHEN Xuefeng1 FENG Jimeng2 In order to investigate the surrounding rock classification method that takes account of the excavation method for single-tube four-lane highway tunnel, the failure process of surrounding rock in the tunnel excavation process is analyzed after a field survey, to identify 3 types of failure characteristics of surrounding rock ranked from good to poor. Then several cases under different surrounding rock classes are calculated by using the numerical simulation method. The failure characteristics of surrounding rock are investigated according to the calculation results.On this basis, the surrounding rock parameters are classified and the tunnel excavation method is determined. At last, the method is demonstrated through field test. As the study results indicate: (1) The 3 failure characteristics including abrupt increase of plastic zone of surrounding rock, formation of tension zone at the arch and overall instability resulting from insufficient bearing capacity are used as the basis for classifying surrounding rock into Classes Ⅲ, Ⅳ and Ⅴ. (2) For single-tube four-lane highway tunnel, according to the results of numerical calculation and analysis of structural failure characteristics, the full face method is suitable under Class Ⅱ surrounding rock condition, the bench-cut method under Class Ⅲ surrounding rock condition, the CD method under Class Ⅳsurrounding rock condition, and CRD method under Class Ⅴ surrounding rock condition. (3) After analysis of the calculation results, the BQ value of the surrounding rock classification is proposed that takes account of the correction of surrounding rock failure characteristics of single-tube four-lane highway tunnel. 2024 Vol. 61 (1): 48-55 [Abstract] ( 43 ) [HTML 1KB] [ PDF 3656KB] ( 285 ) 56 Study on Intelligent Prediction of the Deformation Characteristics of Soft Rock Tunnel Based on SSA-LSTM Model and Its Application WANG Feng In order to accurately predict the surrounding rock deformation during construction of soft rock tunnel, the soft rock tunnel crown settlement and horizontal convergence prediction model has been created by using the long short-term memory (LSTM) neural network, the hyper-parameters of LSTM model have been optimized by using the sparrow search algorithm (SSA), and the calculation process framework for SSA-LSTM has been created. With the soft rock section of Liangwangshan Tunnel being used as an example, field measurement and analysis of large deformation of surrounding rock have been conducted. The crown settlement and horizontal convergence monitoring data is obtained and then substituted into the SSA-LSTM model for calculation. The calculation results are compared against the results of LSTM model and the SSA optimized traditional machine learning model and the errors are analyzed. As the results indicate: the relative error rate of SSA-LSTM model is [-1%, 2%], R2 is 0.998 6, MAPE is 2.345 8%, RMSE is 0.529 8, and this model is the best one of all the models. In order to verify the settlement and deformation of unexcavated section predicted by the SSA-LSTM model, the K33+260 section is used as the object ofstudy and the prediction model for settlement and deformation of unexcavated section is created. According to the results of error analysis, the prediction accuracy of the model is good enough to guide construction. 2024 Vol. 61 (1): 56-66 [Abstract] ( 57 ) [HTML 1KB] [ PDF 7672KB] ( 208 ) 67 Study on the Operational Ventilation Scheme for Super-long Subaqueous Highway Tunnel Based on the Composition of New Energy Vehicles WANG Liang ZHANG Hao As the maximum ventilation length of subaqueous highway tunnels in China keeps increasing and the new energy vehicles take an increasingly high proportion, the operational ventilation scheme design for tunnels is faced with new challenges. Given this problem, several research methods including field measurement, data research and theoretical analysis have been used to conclude that the main emission of new energy vehicles is the particulate matter in fume, and the emission load is largely equal to that of the traditional internal combustion engine powered vehicles.With consideration of the field measurement of temperature and odorous gases, it is recommended that the control standard for super-long subaqueous highway tunnel should not be the air change rate. In view of the actual conditions of a super-long subaqueous highway tunnel, the optimized air demand is calculated as 604.71 m3/s, which is 55% less than the original design. For the longitudinal and semi-transverse ventilation systems, 6 ventilation schemes have been compared and analyzed. After comprehensive examination of the factors including the requirements for civil works, the requirements for electromechanical equipment, the advantages and disadvantages of smoke extraction and evacuation, costs of civil works, costs of electromechanical equipment and annual electricity cost in the operation period, it is recommended to use the air supplied semi-transverse ventilation scheme for superlong subaqueous highway tunnels. 2024 Vol. 61 (1): 67-74 [Abstract] ( 44 ) [HTML 1KB] [ PDF 2682KB] ( 400 ) 75 Construction Risk Assessment for Reconstruction and Expansion of Long-term Operating Metro Stations Based on DBN Model LIU Bingke1 WU Rui2 MA Jianfei2 HE Shaohui2 BAI Shouxing1 MIAO Pengbo1 In order to ensure construction safety in reconstruction and expansion of long-term operating metro sta? tions in complex environment, the risk assessment and control for reconstruction and expansion of the Dongsi Shitiao Station (DSST) of Beijing Metro have been investigated by using such methods as Bayesian network, fuzzy theory,field survey and laboratory test. As the results indicate: (1) According to the station state evaluation, FEM-DBN prework prediction, risk control contingency plan and the OSM-DBN feedback in the construction period, the proposed construction risk assessment method for reconstruction and expansion of long-term operating metro stations can enable dynamic prediction before construction and dynamic feedback in the construction period; (2) This risk assessment method has been applied to reconstruction and expansion of DSST Station. After the risk control measures pro?posed are implemented, the maximum deformation values of the station structure of the existing Line 2 and Line 3 are -1.28 mm and -1.21 mm, and the structure remains safe and stable; (3) The risk assessment results of FEMDBN and OSM-DBN are consistent with the results of the experts' prediction and assessment, and the risk control measures are rational and reliable. 2024 Vol. 61 (1): 75-83 [Abstract] ( 42 ) [HTML 1KB] [ PDF 6356KB] ( 248 ) 84 Study on Water Pressure Distribution Pattern and Limited Drainage Design of Mined Subsea Tunnel JING Yifeng1 WANG Bo1 MEI Jie1,2 XIONG Wenwei1 MENG Qingyu3 The complex geological conditions such as high water pressure and overlying silt layer are the key factors that affect the seepage characteristics and the waterproofing and drainage design of subsea tunnels. In order to systematically investigate the ambient water pressure distribution pattern and water inflow characteristics of subsea tunnel, the analytical solution for seepage field of subsea tunnel that takes into account overlying silt layer has been deduced by using the hydromechanical theories, and the corresponding numerical model has been created. Through comparison and analysis of the theoretical results, the suitability and accuracy of the numerical model have been verified. Through numerical simulation, the optimum limited drainage scheme and rational depressurization value for subsea tunnel have been obtained, the laws by which the factors such as silt layer thickness and coverage rate will affect the tunnel water inflow and the water pressure distribution pattern behind the lining have been further investigated, and the mechanism of action of overlying silt layer on the seepage characteristics of subsea tunnel have been revealed. As the results indicate: (1) As the depressurization value increases, the water drainage of tunnel decreases linearly, while the water pressure behind the lining increases linearly. With the same depressurization value,as the spacing between the circumferential French drain pipes increases, the water drainage of tunnel gradually decreases, while the water pressure behind the lining gradually increases. (2) When the silt layer thickness is 12 m,the optimum limited drainage scheme for mined subsea tunnel is as follows: for semi-closed waterproofing method,the waterproofing system is "circumferential French drain pipe + longitudinal circumferential French drain pipe with 6 m spacing", and the depressurization value is 400 kPa. (3) Increase of the silt layer thickness and coverage rate will decrease the water drainage and, to certain extent, decrease the water pressure behind the lining. At the junction between weakly weathered granite and silt overburden, the water pressure behind the lining changes abruptly,so priority should be given to optimizing the water drainage parameters of the drainage system according to the known silt layer coverage rate or local silt layer thickness. 2024 Vol. 61 (1): 84-95 [Abstract] ( 44 ) [HTML 1KB] [ PDF 7691KB] ( 360 ) 96 Numerical Analysis of Bending Mechanical Properties of Flange Joint of Corrugated Steel Lining HUANG Xuanbo1, 2 DING Wenqi1, 2 ZHANG Qingzhao1, 2 In order to further investigate the bending mechanical properties of the flange joint of corrugated steel lining and the influencing factors, the four-point bending calculation model for flange joint of corrugated steel lining has been created and its accuracy has been verified. An orthogonal test is designed, where the corrugated steel model,flange plate thickness and bolt model are the variables. The failure modes are identified by using the deformation contour plot. The variance analysis and range analysis of the origin stiffness and ultimate bending moment of M-θ curve are conducted. Then the mechanism of interaction of the components in the case of structural failure is revealed with the help of the stress-bending moment curves of flange plate and bolt. At last, the bending moment coefficient α is proposed, to quantitatively differentiate the types of flange joints. As the study results indicate: the stiffness of the structure origin is affected by the corrugated steel model the most. Under positive bending moment load, the ultimate bending moment is dominated by the flange plate, and the failure mode is out-of-plane buckling of flange plate; bolts do not affect it much, but the stress is already at its limit. Under negative bending moment load,the ultimate bending moment is affected by both the bolt and flange plate, and the failure mode can be controlled by the flange plate, bolt or both; the relative bending moment coefficient α proposed can be used to quantitatively and accurately identify the failure mode. Under pure bending load, the maximum Mises stress of flange plate and bolt experiences four-stage growth. Under negative moment load, the maximum Mises stress of flange plate does not change significantly with the bolt model. 2024 Vol. 61 (1): 96-106 [Abstract] ( 39 ) [HTML 1KB] [ PDF 7673KB] ( 153 ) 107 Study on the Effect of Internal Structure Construction Mode on the Explosive Dynamic Response in Highway-Railway Combined Shield Tunnel XIAO Mingqing1, 3 FENG Kun2 WANG Shaofeng1, 3 YANG Hao2 GUO Wenqi2 In order to ascertain how the various internal structure construction modes affect the blast resistance of shield tunnel segment and internal structure, the 3D fine numerical calculation model for semi-prefabricated internal structure and cast-in-situ internal structure has been created for the purpose of engineering application in highway-railway combined shield tunnel, and the dynamic response and damage characteristics of segment and internal structure under the effect of blast load have been calculated and analyzed by using the explicit dynamic time history method. The study results indicate: compared with cast-in-situ internal structure, semi-prefabricated internal structure shows stronger acceleration response at the connections under the effect of blast load and its longitudinal acceleration peak is attenuated faster, but the internal structure sustains less severe damage. In addition, the acceleration peak at segment joint experiences abrupt change, and when the explosive is detonated in the middle of the traffic space, the acceleration peak at segment joint of semi-prefabricated internal structure is 20%~49% less than the acceleration peak at segment joint of cast-in-situ internal structure. 2024 Vol. 61 (1): 107-116 [Abstract] ( 64 ) [HTML 1KB] [ PDF 6023KB] ( 199 ) 117 Analysis of Stress Characteristics of Specially Lined Segment of Superlargediameter Shield Main Tunnel during Mechanically Excavating Cross Passage ZHENG Zhenji1 HUANG Shuhua2 CHEN Xiangsheng1 ZHANG Liang2 LIU Haoming1 SHENG Jian2 SU Dong1 In this paper, the 6# cross passage of Haizhu Bay Tunnel, the first mechanically built cross passage of a superlarge-diameter shield main tunnel in China, is used as the example. First, the suitability of different types of specially lined segments in construction of mechanically built cross passage of a superlarge-diameter shield main tunnel is analyzed. Then the dynamic explicit finite element method is used to create a fine model that takes into account cutterhead cutting and material damage failure, so as to investigate the stress characteristics of inlaid steel plate specially lined segment during construction of mechanically built cross passage. As the results indicate: In the mechanical construction process, the superlarge-diameter main tunnel experiences elliptical deformation. After cutting of the opening, both sides of the opening exhibit noticeable compressive stress concentration. Under the effect of the advancing cutterhead, major deformation increment and inter-ring dislocation are concentrated at the two sides of the opening. When inlaid steel plate specially lined segment is installed, the stress concentration of the structure at the sides of the hole in the cutting process is obviously abated, the deformation at the opening side is decreased by 0.5~1.5 mm, and the structure is made safer. Before construction, the inlaid steel plate of the special lining is welded into the whole structure, to enhance the integrity of the segments and to keep the inter-ring dislocation deformation of main tunnel at a low value. 2024 Vol. 61 (1): 117-124 [Abstract] ( 48 ) [HTML 1KB] [ PDF 5694KB] ( 191 ) 125 Study on Rational Switchover Point of EPB/Slurry Dual-mode Shield Based on the Improved Spewing Model ZHANG Ruyue1 ZOU Fuqing2 FANG Yong1 GENG Fangchuang2 ZHUO Bin1 WANG Yubo1 For tunnelling in a stratum that contains both high and low water levels, the EPB/slurry dual-mode shield machine is used, in order to ensure both safety and economic efficiency of underwater shield tunnel construction. In practical works, however, switchover between the two modes can be often irrational and subjective, so the dualmode shield machine cannot be used to its full efficiency. In this paper, the shield tunnel from Baotai Avenue to Changhong Square, a rail transit project of Ziyang Metro, is used as the example. First, the principle and basis for switchover between the slurry and EPB modes is determined through theoretical analysis. Then the blowout calculation model is improved, and three-dimensional finite element modeling is conducted by using COMSOL Multiphysics,so as to obtain the methods that are used to quantitatively calculate and identify the blowout risk of EPB shield machine and the effects that are generated by the relevant parameters of the screw conveyor. As the results indicate: According to field verification, blowout can be viewed as the principle for identifying the rational switchover point. The improved blowout model is clearly superior to the previous models in terms of the rational switchover point of the two modes, for it can be used to more accurately identify the risk range of the EPB mode and to guide mode switchover of dual-mode shield machine in a safe, economically efficient and rational manner. The difference between the result of the improved theoretical formula and that of the three-dimensional simulation calculation is no more than 30% and both results exhibit similar variation pattern. The pore water flow rate of screw conveyor is in positive correlation with the cylinder diameter and screw pitch of the screw conveyor and in negative correlation with the diameter of screw shaft and length of screw conveyor. 2024 Vol. 61 (1): 125-136 [Abstract] ( 40 ) [HTML 1KB] [ PDF 6300KB] ( 127 ) 137 Analysis of the Impact of Large Diameter Shield Tunnel Crossing Existing Expressway Bridge and Culvert ZHANG Qing1 ZHEN Wenzhan1 FENG Kun2 To further investigate the influence of large diameter shield tunnel construction on the surrounding struc? tures, based on a large diameter shield tunnel project of a railway engineering in Chengdu, combined with the characteristics of small spacing and shallow soil crossing highway bridge and culvert, the numerical analysis method is adopted to consider the interaction between pile-soil-tunnel, and a three-dimensional finite element calculation model is established. The displacement trends of ground surface, bridge pile, pedestrian tunnel and isolation pile caused by shield tunnel construction are analyzed, The simulation results show that the excavation unloading of shield tunnel forms an obvious settlement trough on the surface, but the isolation pile can effectively block the soil deformation and reduce the surface settlement; the horizontal surface settlement curve shows a sudden change at the position of the isolation pile, and the surface settlement value before and behind the isolation pile decreases by 27% and 40-50% respectively; the vertical surface settlement curve decreases in the range of the isolation pile and shows a W-shaped distribution. The bridge pile is affected by the tunnel excavation unloading, and produces additional deformation and bending moment to the tunnel side. The value of the tunnel body range increases from the bottom to the top and then decreases, and the vertical influence range of the small diameter shield is tunnel large. At the same time, the additional deformation of the structure floor caused by the shield tunnel under the pedestrian tunnel is large, and the maximum value of settlement is 7.5 mm. The above numerical calculation results are close to the field measured results, which verifies the accuracy and feasibility of the numerical simulation results. 2024 Vol. 61 (1): 137-145 [Abstract] ( 46 ) [HTML 1KB] [ PDF 5222KB] ( 283 ) 146 Analysis of the Results of General Dewatering and Drainage Measures and Ground Stability of Tunnel in Water-rich Hypabyssal Rock DUAN Xianbiao1 HUANG Xuanbo2，3 ZHANG Qingzhao2，3 XU Yongjin1 In order to investigate the results of the general dewatering and drainage measures for a tunnel in waterrich hypabyssal rock stratum and how these measures will affect the tunnel stability, the Wangjiazhai Tunnel of Lincang-Qingshuihe Expressway is used as an example in this study. By using the extracted water quantity on site and the stratum water level monitoring data, the finite element model for dewatering and drainage of tunnel in water-rich hypabyssal rock stratum is created, so as to calculate and analyze how the general dewatering and drainage measures will affect the distribution of pore water pressure/moisture content. Given the shear corrected strength of the soil masses with different moisture contents, the sequential coupling method is used to analyze the tunnel stability after dewatering and drainage. As the results indicate: the general dewatering and drainage measures will effectively reduce the moisture content of the tunnel face and increase the strength of soil mass. After dewatering, the deformation on site is reduced by 80% maximally. The stratum water pressure decreases linearly as the extracted water quantity increases, the moisture content decreases in inverse proportion, and a dewatering funnel is formed between the left and right deep wells. The deep wells play the main role in dewatering. When the average water discharge of single well reaches 400 m3/d, the unsaturation state appears in the grouting circle. After the general dewatering and drainage measures are implemented at the site of Wangjiazhai Tunnel, the strength of hypabyssal rock increases, and the safety factors of the left and right tunnels are 1.99 and 1.62. 2024 Vol. 61 (1): 146-155 [Abstract] ( 46 ) [HTML 1KB] [ PDF 6931KB] ( 209 ) 156 Study on Integrated Multi-objective Optimization of TBM Construction Method Based on the Improved Lightning Search Algorithm LIU Xiaoxuan1 TANG Xiao1 ZHANG Shuai1 TAN Zhichao2 WU Dong1 To address the uncertainties in construction of drainage gallery by TBM method, the 3 objective functions including construction duration, work cost and work quality have been established by using the critical path method,and the integrated optimization model that takes into account the risks in the 3 objective functions has been created by using the construction organization methods in different construction processes as the decision-making variables.To solve this model, a new lightning search algorithm has been invented by updating the energy of electric discharge body and changing the iteration method of electric discharge body, and the effectiveness of the new algorithm has been verified through simulation of the 3 sets of test functions. The example verification of the model has been conducted by using the excavation of the drainage gallery of Zhejiang Jinyun Pumped Storage Power Station as the example. The integrated optimization model has been solved by using the improved lightning search algorithm, to generate several sets of 3D Pareto optimal solutions that are evenly distributed. The results of optimization prove the rationality of the integrated optimization model for multi-objective construction organization and management and the effec? tiveness of the improved lightning search algorithm, and thus afford the basis for the decision makers to conduct precise and intuitive construction organization and management. 2024 Vol. 61 (1): 156-164 [Abstract] ( 55 ) [HTML 1KB] [ PDF 4530KB] ( 218 ) 165 Analysis of Critical Suspended Span Length and Stress of Subsea Pipeline LIU Cheng1 JIA Beibei1 CHEN Shuyang1 SUN Fuxue2 Under the long-term effect of non-linear wave load, the seabed near the subsea pipeline in shallow water area is very susceptible to local scour erosion and transport, which will result in suspension and destabilization of the pipeline. To maintain the stability of subsea pipeline, the critical suspended span length of pipeline must be determined. The critical suspended span length is determined by using the wave force sustained by the suspended section of pipeline in shallow water area as calculated by the Morison formula and also the relation between the maximum bending stress of pipeline and the allowable stress of the material. The material parameters are selected according to practical engineering, the law by which the suspended span length and wave parameter will affect the stress distribution of subsea pipeline is analyzed by using the Flac 3D numerical calculation software, and the variation pattern of the correction factor k of mid-span bending moment is calculated. As the results indicate: the numerical solution of the bending moment of the suspended structure is greater than the solution generated by the theoretical formula, but as the suspended span length increases, the difference between the two solutions shows a trend of decreasing. With the same span length, the increase of wave height, decrease of wave length or increase of period will cause the deformation and maximum bending moment of pipeline to increase. As the span length increases, the maximum bending moment will move near the span end, which indicates that the failure point position of pipeline is related to the span length. The analysis result is used for analysis of practical cases, to provide the basis for identifying the failure of suspended pipeline and determining the timing of maintenance. 2024 Vol. 61 (1): 165-173 [Abstract] ( 40 ) [HTML 1KB] [ PDF 4492KB] ( 142 ) 174 Study on the Effects of Seawater and High Temperature Environment on the Rheological Properties of Bentonite Slurry ZHOU Ji1 WANG Xihao2 KANG Song2 DAI Zhenyang2 For tunnelling in seabed by a slurry shield, it is of great importance to prepare a suitable slurry that en? sures desirable rheological properties and permeability characteristics in an environment with seawater intrusion and high temperature. In order to ascertain the effects of high temperature and seawater intrusion on the rheological property of bentonite slurry, a set of rheological tests have been conducted by using the Brookfield RST Soft Solids Tester Rheometer, and the flow pattern and constitutive model of slurry in an environment with high temperature and seawater intrusion have been analyzed. As the results indicate: In high temperature environment, bentonite slurry clearly experiences thinning induced by temperature rise. As the temperature increases, the rheological model of bentonite slurry does not change. With seawater intrusion, the water retention capacity and physical stability are diminished and it experiences segregation. The bentonite slurry virtually loses the rheological characteristics of powerlaw fluid and yield fluid, and the flow pattern of slurry is degraded to that of Newtonian fluid. Besides, the results of electron microscope scanning indicate that the space structure of fresh water slurry appears as lumpy flocculent shape, there are dense and contiguous lumps, and the space structure is complete and dense. In 50% of the seawater slurry, space structure appears as flaky form, there is noticeable gap between the flakes, and local areas have accumulation of discrete particles. 2024 Vol. 61 (1): 174-181 [Abstract] ( 41 ) [HTML 1KB] [ PDF 5818KB] ( 120 ) 182 Analysis of the Effect of Slurry Rheological Model on the Pressure Loss Characteristics of Slurry Discharge Pipe of Slurry Shield LIU Hongzhi1 XU Shankun1 GUO Yidong2,3 FANG Yingran2,3 LI Xinggao2,3 In order to ascertain the effect of slurry rheological model on the results of pipe pressure loss calculation of slurry shield, the three-dimensional transient slurry-muck multiphase flow coupling model has been created by using the CFD-DEM coupling method, the pressure loss characteristics of slurry discharge pipe of slurry shield are identified, the rheological parameters of the rheological model in the coupling model are determined through rheological test, and the shape and size of muck are determined through 3D scanning. In addition, through comparison with the model test results, the applicability of the rheological model and the accuracy of the calculation results have been analyzed. As the study results indicate: in solving the pipe pressure loss of slurry-particle two-phase flow, the calculation results of H-B model have the smallest error, which is about 6%, the calculation results of Bingham model have the second-smallest error, which is about 8%, and the calculation results of Power law model have the greatest numerical error, which is about 18%. Therefore, for the numerical calculation that has the highest requirement for calculation accuracy, the H-B model is recommended for the slurry rheological model. With comprehensive consideration of the calculation accuracy and the time cost of calculation, the Bingham model is recommended for the slurry rheological model. 2024 Vol. 61 (1): 182-189 [Abstract] ( 48 ) [HTML 1KB] [ PDF 4224KB] ( 264 ) 190 Test and Analysis of the Effect of the Freezing Construction of Subway Cross Passage on Adjacent Shield Tunnel Segment SHI Yufeng1,2 CAI Jiacheng1 ZHANG Tao3 ZHANG Hanqiu4 LI Junxian1 GU Dajun5 In order to ascertain how the freezing method used for construction of subway cross passage will affect the adjacent segments, a site test has been conducted at the 2# cross passage of the Yaohu East Station—Maqiu Station section of Nanchang Metro Line 1 East Extension project, and the water & earth pressure of adjacent segments,structural internal force, vertical displacement, clearance convergence and ground settlement have been monitored in long term. As the results indicate: (1) Before excavation of the cross passage, the frost heave force will cause the water & earth pressure outside the adjacent shield tunnel segment rings to increase. The maximum values of the pressure are 170 kPa and 150 kPa, which are increased by 11.1% and 15.4% as compared with the values before freezing. After stabilization of the soil mass, the maximum values of the water & earth pressure are 173 kPa and 148 kPa,which are increased by 12.4% and 13.8% as compared with the values before freezing. (2) Under the effect of stratum freezing, the maximum bending moment and axial force of the adjacent segment are -103.1 kN·m and 2 314 kN,which are increased by 28.09% and 19.8% as compared with the values before freezing. (3) Under the effect of the frost heave force, the safety factor of the segment at the frozen side is reduced, and the safety factor near the arch bottom is reduced by the greatest margin, which is 22.9%. After unfreezing and stabilization of the soil mass, the safety factor of each segment is increased, but still less than the value before freezing. (4) In the construction period, the maximum heave on the surface is 2.18 mm and the maximum settlement 1 mm. The maximum upward displacement of the segment is 2.3 mm and its maximum settlement 0.9 mm. The maximum value of convergence deformation of segment is no more than 3.4 mm. These results indicate that the freezing method used for construction of subway cross passage is highly feasible. 2024 Vol. 61 (1): 190-199 [Abstract] ( 45 ) [HTML 1KB] [ PDF 6531KB] ( 168 ) 200 Study on Model Test of Existing Shield Tunnel Uplift ZENG Yi1 GAO Yue2,3 WU Peilin2,3 ZHANG Xiaolong1 FU Yanbin2,3 Tunnel uplift correction is an effective way of controlling tunnel settlement, but uplift correction is likely to cause overconvergence and thus secondary damage of the tunnel. In light of this, an existing shield tunnel uplift model test system is designed. Separate longitudinal joints are installed to conduct longitudinal structure simulation,in order to examine how the longitudinal joints in the tunnel will reduce the integral stiffness. With comprehensive consideration of the influencing factors including uplift magnitude, uplift angle and stiffness of section, the variation pattern of vertical displacement and cross-section of the tunnel during uplift correction is investigated. As the results indicate: keeping an uplift angle less than 45° will prevent excessive deformation during tunnel uplift; when the uplift position is near the longitudinal joint of the tunnel, the displacement difference between the active uplift ring and the adjacent passive uplift ring will decrease, and the longitudinal displacement curve of the tunnel be- comes gentle; installation of internal support will cause the uplift model to change from section deformation to global uplift. 2024 Vol. 61 (1): 200-207 [Abstract] ( 42 ) [HTML 1KB] [ PDF 4628KB] ( 182 ) 208 Study on Field Test of Joint Waterproofing of Long-segment Heavy-tonnage Prefabricated Assembled Utility Tunnel MA Huabing1 FENG Liangping2 WANG Hengdong3 XIAN Jianping4 SHANG Dongfan5 CUI Guangyao6 In order to demonstrate the waterproof performance of the long-segment heavy-tonnage prefabricated assem? bled utility tunnel in the startup zone of Xiong'an New Area, the field test of joint waterproofing of long-segment heavy-tonnage utility tunnel has been conducted, and the waterproof performance of two types of waterstops after water injection and pressurization in different cases has been analyzed. As the results indicate: both types of waterstops can meet the waterproofing requirements for the tunnel in normal operation. In the case of tensioning force induced failure of the two types of waterstops, ClassⅠwaterstop has 2 leakage points and Class Ⅱ waterstop has no leakage point. The reason is that ClassⅠwaterstop is spliced when kept still and the nonuniform splice width at element joint will result in tensioning force induced failure and thus water leakage. In the case of element dislocation of the two types of waterstops, ClassⅠwaterstop has no leakage and Class Ⅱ waterstop has 3 leakage points. The reason is that ClassⅡwaterstop is spliced when suspended and its tensioning force is less than that of ClassⅠwaterstop, so leakage is more likely to occur in the case of dislocation. For this project, it is recommended to use Class Ⅱwaterstop for waterproofing of element joint. 2024 Vol. 61 (1): 208-215 [Abstract] ( 39 ) [HTML 1KB] [ PDF 3924KB] ( 134 ) 216 Study on Interaction Mechanism and Key Parameters of Shield Cutter Cutting the Pile Foundation—Case Study of Haizhu Bay Shield Tunnel Project WANG Defu When construction of a shield tunnel in a central urban area encounters the pile foundation of an existing building (structure), having the shield cutter directly cut the pile foundation is the preferred option. With the Haizhu Bay superlarge-diameter shield tunnel used as an example, the cutter-pile foundation-stratum dynamic cutting simulation model is created by using the numerical simulation method, in order to intensively investigate the interaction mechanism of shield cutter cutting the pile foundation. Through sensitivity analysis of the key parameters such as cutter spacing, cutter ring penetration, cutterhead rotating speed and pile foundation position relative to cutterhead,the optimum values of the key parameters for the cutter to cut the pile foundation are obtained. As the results indicate: if the cutter spacing is excessively large or the cutter ring penetration is excessively small, the use of cutter to cut the pile foundation has better results and higher utilization rate. If the penetration increases, the scope of influence of the interaction between cutter and stratum-pile foundation model increases, which is beneficial for breaking and removing the pile foundation materials. If the penetration and cutterhead rotating speed are set improperly, the load of cutter breaking the pile foundation will increase. For the Haizhu Bay superlarge-diameter shield tunnel, the optimum cutter spacing is 80 mm, optimum penetration 45 mm and optimum cutterhead rotating speed 2 r/min. 2024 Vol. 61 (1): 216-228 [Abstract] ( 46 ) [HTML 1KB] [ PDF 14302KB] ( 293 ) 229 Study on the Strategy for Disposal and Management of Waste Slurry and Sopil from Large-diameter Slurry Shield WU Yankun1,2 CHEN Jian2,3,4 LI Xiaodong1 SU Xiuting2,4 In order to dispose of the waste slurry and spoil generated during construction of slurry shield, the proper? ties of slurry and spoil from large-diameter slurry shield and its disposal method are analyzed. By using the Yellow River Jiluo Road Tunnel in Jinan as the example, different methods for disposal of waste slurry and spoil are compared and analyzed. As the results indicate: Flocculent precipitation and belt pressure filtration are the most efficient disposal methods. The spoil that has experienced plate-frame pressure filtration can be directly transported out, but will impact the environment. For silty clay stratum, it is preferable to use the dewatering process that combines centrifugal dewatering and pressure filtration dewatering. At the end, the suggestions are offered regarding disposal and reuse of shield spoil from the perspective of management. 2024 Vol. 61 (1): 229-235 [Abstract] ( 57 ) [HTML 1KB] [ PDF 3496KB] ( 167 ) 236 Optimization and Application of Installation Path of Prefabricated Structure in Large-diameter Shield Tunnel XUN Haolin1 LI Peinan2 LIU Jun1 SONG Xingbao3 QIN Yuan3 KOU Xiaoyong3 ZHAI Yixin3 The traditional shield tunnel construction process has the problems such as unadvanced construction pro? cess of prefabricated members and low efficiency of construction. By analyzing the motion characteristics of the prefabricated members of shield tunnel in the installation process, the path of intelligent erection robot during installation of prefabricated members in the tunnel has been further optimized. According to practical installation of center diaphragms in actual tunnel projects, it is determined that the position and orientation of the internal structure on the transport vehicle must be planned according to the characteristics of the members and the working environment of the erector before path optimization is done. After the member is transported to its position, coordinate system must be created on the prefabricated member by using the right hand rule and the corresponding equation of motion must be established, to select the optimal motion path. At last, the erector control is further optimized according to the motion path. As the results indicate: (1) The intelligent center diaphragm erection robot can accomplish installation of the prefabricated members such as center diaphragm and arcuate member in a tunnel, its erection accuracy can meet the member installation requirements, and the motion execution accuracy of oil cylinder is up to 0.5 mm.(2) In the construction process that uses an intelligent erector, the installation error is reduced from 20 mm to 1 mm,and the number of arcuate members and center diaphragms installed in 24 h is increased to 30，35 respectively. (3)The installation path is optimized by using the position and orientation of center diaphragm and the equation of motion, to increase the center diaphragm installation efficiency in shield tunnel and enhance the control accuracy of construction with prefabricated members. 2024 Vol. 61 (1): 236-244 [Abstract] ( 41 ) [HTML 1KB] [ PDF 4251KB] ( 186 ) 245 Study on Construction Quality Control Criteria for Prefabricated Integrated Arcuate Members HAO Pengfei The construction quality of prefabricated integrated arcuate members is a key element in construction of large-diameter shield tunnel, so it is necessary to establish effective and rational control criteria for the construction quality of prefabricated integrated arcuate members. In light of this, the construction quality control criteria for the prefabricated sub-rail structure or box culvert of the existing projects are reviewed, the composition and construction process of prefabricated integrated arcuate members are explained, the construction quality control criteria for prefabricated integrated arcuate members are proposed, and the criteria are practiced in actual works. As the results indicate, construction of the arcuate members that are built under the criteria proposed has high efficiency and good quality, and the members perform well in service. 2024 Vol. 61 (1): 245-251 [Abstract] ( 43 ) [HTML 1KB] [ PDF 3870KB] ( 218 ) 252 Study on Roof Caving Mechanism and Support Scheme Optimization of Tunnels in Thin-bedded Rock Mass WEI Chuanwen1 WANG Xianglong1 YANG Xuxu2 ZHAO Yudi1 SHAO Xing3 MAN Xinjie1ZHANG Changan3 ZHOU Yangyang1 ZHANG Zuoshun2 With the Caojiading Tunnel on Linzi-Linyi Expressway in Shandong being used as an example in this study, the three-dimensional discrete element numerical calculation software 3DEC is used to create the analysis model, in order to investigate the roof caving mechanism of a tunnel in thin-bedded rock mass. Through roof separation monitoring and plastic zone analysis of the crown rock mass, it is determined that the root cause of crown roof caving is the fact that the original rockbolt support system fails to effectively control the roof caving height. On this basis, the anchor cable support scheme is proposed and the support parameters are optimized and analyzed. 3 variables are analyzed, including various anchor cable lengths, number of roof anchor cables and side wall rockbolt quantity ratio. According to the numerical calculation, the optimized anchor cable support scheme is selected, where there are 5 anchor cables which are 5.5 m long in the scope of the roof and the side wall rockbolt quantity ratio is 0.5. A tunnel section with the risk of roof caving is selected to conduct the anchor cable support test. According to analysis of the monitoring data, the average axial force of anchor cable at the tested section is increased by 65.1%, 31% and 8.5% at the position below the spandrel, at the position above the spandrel and at the crown as compared with the average axial force of rockbolt at the same positions in the common section. This indicates that anchor cable support system can control crown roof caving more effectively than rockbolt support system. 2024 Vol. 61 (1): 252-259 [Abstract] ( 42 ) [HTML 1KB] [ PDF 5187KB] ( 280 ) 260 Study on Deterioration Characteristics of Modified Slurry Shield Spoil Based on Freeze-thaw Cycle Test ZHANG Jianyong Modifying the muck discharged from a shield tunnel into subgrade material will significantly increase the utilization efficiency of resources, but the freeze-thaw conditions will create safety hazard. By using a shield tunnel of Heping Avenue in Wuhan as the example and using the spoil from large-diameter slurry shield as the study object, the shield spoil is modified by adding the independently developed waste solid based gelatinizer (Cement-SlagGypsum-Alum, CSGA) and basalt fiber (BF), and the shield spoil modified by CSGA-BF is subjected to freezethaw cycle test, in order to investigate how the parameters such as amount of basalt fiber and number of freeze-thaw cycles will affect the appearance deterioration characteristics, mechanical properties and microscopic damage mechanism of improved shield spoil. As the results indicate: Under the effect of freeze-thaw cycle, the volume of modified spoil changes in a wave-like pattern, and it generally exhibits volume expansion. As the number of freeze-thaw cycles increases, both the unconfined compressive strength and modulus of elasticity of the modified shield spoil decrease non-linearly. Adding a proper amount of basalt fiber will increase the friction at the reinforcement-soil interface,which is important to frost resistance of spoil. However, excessive amount of fiber will degrade the strength of the specimen. When the number of freeze-thaw cycles is 9, the compressive strength and modulus of elasticity of the modified shield spoil stabilize, and the pores become interconnected. 2024 Vol. 61 (1): 260-271 [Abstract] ( 41 ) [HTML 1KB] [ PDF 8383KB] ( 227 ) 272 Study on Seepage Crystallization Pattern of Tunnel Shotcrete of Different Ages TONG Yueping1 TIAN Chongming1 YE Fei1 JIANG Yin1 ZHANG Junyuan1 WU Bowen1WANG Han1 LI Wenhui2 The crystallization induced blockage defect in tunnel drainage system is closely related to groundwater seepage in shotcrete. In order to ascertain the correlation between the curing age of shotcrete and crystallization induced defect, a home-built indoor simulation device is used to simulate the seepage-crystallization process of tunnel shotcrete. The mass of crystal and the pH value and calcium ion concentration of effluent solution from drainage pipe have been measured, and XRD, thermogravimetric analysis, electron microscope scanning and mercury injection test have been conducted, so as to reveal the deterioration process of the shotcrete of different ages and the crystallization pattern in drainage pipe under groundwater seepage conditions. As the results indicate: (1) The curing age of shotcrete is a key factor that affects the crystallization induced defect of tunnel, and the early age affects it particu? larly significantly. Under seepage conditions, the crystal mass in drainage pipe in the concrete with 2 h age is essentially 30 times that in the concrete with 28 d age; (2) Longer concrete curing age means the pH value will decrease faster, pH value will stabilize sooner and calcium ion concentration will stabilize sooner; (3) After 60 d of internal seepage in the concrete of different ages, only very small amount of ettringite and C-S-H gel are observed inside the concrete, the structure is uneven, and the concrete has high total porosity; The interior of concrete contains calcium hydroxide crystal, and as the curing age increases, the crystal changes from small amount of flocculent crystal in unstable state to large amount of lumpy crystal in stable state; Longer curing age means less concrete hydration products are dissolved out. According to the thermogravimetric analysis, the calcium hydroxide content of the concrete with 28 d age is 5.9 times that of the concrete with 2 h age. 2024 Vol. 61 (1): 272-282 [Abstract] ( 36 ) [HTML 1KB] [ PDF 6370KB] ( 165 )

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