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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2022 Vol.59 Issue.6 Published 2022-12-25 1 Study on the Reasons and Countermeasure of Ground Subsidence Caused by Slurry Shield Construction Covered by a Giant Thick Rock Formation ZHU Weibin1 MI Jinsheng1 XIE Wenda2 MENG Fanjing2 It is generally recognized in the industry that slurry shield construction is superior to earth pressure shield in terms of ground subsidence control accuracy. But in recent ten years, many ground subsidence had happened caused by slurry shield machine construction operating under“giant thick rock”condition, diameter of shield machine was from 5 m to 15 m，even several of them led to huge economy lost and society impression.In view of the above problems, the author of this paper has found the main characteristics of such subsidence events through in-depth tracking, analyzing and researching of typical cases. (1) Shield machine was in fracture developed strata or mixed face ground with weathering slot or surface borehole locations; (2) Shield machine had appeared“clogging”or“claycake”before ground subsidence occurred; (3) Flush excavation chamber frequently was used in order to eliminate “clogging”as soon as possible and dredge slurry circulation lines, the result led to support pressure unstable. Based on this, the reasons and mechanism of ground subsidence caused by slurry shield construction under“giant thick rock”are deduced from geology, shield machine, construction technical measures and management, etc.Author answered the query comprehensively and on that basis, points out countermeasure suggestion for the reference of industry personnel. 2022 Vol. 59 (6): 1-13 [Abstract] ( 492 ) [HTML 1KB] [ PDF 13754KB] ( 798 ) 14 Prediction Method for Slurry Balance Shield Tunneling Speed Based on Mean Filtering & Denoising and XGBoost Algorithm DU Qingfeng1 ZHANG Shuangli1 ZHANG Chenxi1 LI Xuhui2 XIAO Yongsheng2 LI Xiaojun3 In the process of slurry balance shield tunneling, the tunneling speed has a significant impact on cutter wear, synchronous grouting and shield attitude. A reasonable tunneling speed is of great significance for improving construction efficiency and reducing construction risks. The historical data collected by the PLC system is used to build an intelligent prediction model to predict the tunneling speed in real time, which is an important basis for the realization of unmanned shield and intelligent control in the future. Based on the time series data of tunneling parameters collected in the Pearl River Delta Water Resources Allocation Project, the tunneling speed is selected as the prediction target, the Pearson correlation analysis method is used to extract important characteristic parameters,the mean filtering method is used to denoise the time series data of characteristic parameters, to calculate the mean and the variance of the denoised series to form the feature vector, and to build the corresponding prediction model based on the XGBoost algorithm. The influence of data sets before and after denoising by mean filtering and different hyper-parameters in the XGBoost algorithm on the prediction performance of the model is discussed. The results show that under the 5-fold cross validation, a more accurate prediction model of the tunneling speed of the shield machine can be established by using the data after denoising processing with mean filtering. With the XGBoost algorithm, the prediction accuracy of the tunneling speed of the shield machine based on the denoised data set has reached 99.97%, and the prediction accuracy based on the non-denoised data set has also reached 99.94%, which is superior to the mainstream random forest algorithm, the SVR algorithm and the GBDT algorithm. The experimental results prove the noise reduction effect of the mean filtering method on the time series data and the feasibility of using XGBoost algorithm to predict the tunneling speed. 2022 Vol. 59 (6): 14-23 [Abstract] ( 485 ) [HTML 1KB] [ PDF 2823KB] ( 523 ) 24 Crack Identification of Tunnel Lining Based on Neural Network and Edge Correction CHEN Yingying1,2 LIU Xingen1,2 HUANG Yongliang3,4 LI Mingdong1 To address the problem of complex imaging background of tunnel lining, this paper proposes a fast image screening and crack region localization based on convolutional neural network, as well as a tunnel lining crack identification method based on binary tree and curve fitting, in view of the feature that cracks mostly exist in reticular form and burr-shaped bifurcation areas. First, the rapid screening of massive amounts of pictures and locating of approximate position of crack areas are conducted by gridding the area segmentation and using convolutional neural networks to judge the category of the areas. Then the original crack skeleton is obtained by the Zhang-Suen refinement algorithm for the detected crack areas. The skeleton binary tree of the cracks is constructed based on the correlation information between crack points and the crack skeleton is corrected by using the node screening rule of maximum distance. Based on the correction results, the crack edges are further corrected to retain the crack mesh pattern while realizing the elimination of unreasonable areas such as areas with short bifurcations and joints Finally, the crack trajectory is corrected based on least-square curve fitting and the broken parts of the crack trajectory are connected based on the binary tree node information to obtain the complete trajectory. The test results show that the proposed method can accurately screen out 98.73% of the lining images that do not contain cracks; the use of binary tree-based edge correction has improved the segmentation accuracy of the cracks and ensured the integrity of the crack trajectory by trajectory correction. 2022 Vol. 59 (6): 24-34 [Abstract] ( 445 ) [HTML 1KB] [ PDF 5263KB] ( 605 ) 35 Distribution and Development Characteristics of Urban Road Tunnels in China XU Fuqiang DU Zhigang CHEN Can Based on the information collection and sorting of 406 urban road tunnels, the statistical analysis of urban road tunnels in China is carried out from the aspects such as the year of service, provinces and cities where road tunnels are distributed, the obstacles passed through (water, buildings, mountains), tunnel types (length, speed, lane) and portal types (multiple portals, orientation, separation, subsidence, curve), which clearly and directly reflects the development scale of urban road tunnels in China, shows the construction characteristics of urban road tunnels in China, and provides basic support for further development research of urban road tunnels in China. 2022 Vol. 59 (6): 35-41 [Abstract] ( 394 ) [HTML 1KB] [ PDF 3612KB] ( 586 ) 42 Study on the Upper Limit of Stability of the Slope Excavation Face of a Shield Tunnel WANG Zijian1 LIU Teng2 JI Xiaodong1 LIU Xueyan1 The stability of the slope excavation face of a shield tunnel is studied with the upper limit analysis meth? od based on the existence of a slope on the overlying soil layer of the tunnel, to build a stability analysis model of slope excavation face and provide a calculation formula of ultimate support pressure. Through the comparison of numerical simulation results, the impact of various factors (thickness of covering soil, cohesion and angle of internal friction) at a constant slope is analyzed; the diagrams and tables are used to provide the variations in the influencing coefficients of support pressure at three different slopes of covering soil with the burial depth. The results show that the support pressure is reduced with an increase in the soil cohesion and angle of internal friction and is increased with an increase in the burial depth, and the support pressure is in direct proportion with the slope of covering soil. 2022 Vol. 59 (6): 42-50 [Abstract] ( 484 ) [HTML 1KB] [ PDF 3123KB] ( 495 ) 51 Study on Rapid Assessment of Battle-induced Structure Damage Based on the Subway Station Target LI Hu1, 2 HAN Gang1 HUANG Yongliang1 SONG Xie1 LI Dayong1 Analytical research was conducted systematically on the battle-induced structure damage based on the subway station target, and combined with the common ways to strike the urban subway station structure with conventional weapons, a simple analysis of target characteristics was carried out and a calculation and assessment flow was established for the battle damage to the subway station structure. Based on the establishment of the criteria for damage, a more detailed analysis of battle-induced structure damage was conducted, key parameters, such as radius of collapse, peak value of equivalent uniformly distributed dynamic load at different areas, vibration acceleration and vibration time, were calculated, and calculation was illustrated according to the specific examples of penetration and explosion above the subway station. From the results of calculation, it can be seen that the established method and flow of calculation and assessment of battle-induced structure damage can rapidly and accurately evaluate the damage to subway stations and also provide a useful reference for research into the protection of subway stations and emergency repair and rescue after battle-induced structure damage. 2022 Vol. 59 (6): 51-60 [Abstract] ( 427 ) [HTML 1KB] [ PDF 2896KB] ( 544 ) 61 Study on the Decision-making System for the Selection of Highway Tunnel Face Layout Type Based on the Fuzzy Comprehensive Evaluation Method ZHAO Aijun1 WEI Yanqing2 HUANG Taiping1 To explore the decision-making method of highway tunnel face selection, a decision indicator system of three-layer highway tunnel face layout type is built according to the Longquanshan Tunnel Project of Chengdu Tianfu International Airport. The face layout scheme of three types of highway tunnels and their decision-making standards were determined to employ the fuzzy comprehensive evaluation (FCE) method to solve the decision-making problem of tunnel face selection. When the 4-tube layout is adopted in the Longquanshan Tunnel, the membership value of the Longquanshan Tunnel face is calculated to be 0.608 2 and the 4-tube layout is recommended. The practice shows that the decision-making system of highway tunnel face layout type proposed is highly reasonable and reliable. 2022 Vol. 59 (6): 61-69 [Abstract] ( 451 ) [HTML 1KB] [ PDF 4190KB] ( 580 ) 70 Study on the Thermal Insulation and Shock Absorption Technology for Tunnels Crossing the Heat-conducting Fault in a Highly Seismic Zone CUI Guangyao1 SHI Wenhao1 WANG Daoyuan2 WANG Mingsheng3 To further improve the thermal insulation and shock absorption performance of tunnels crossing the heatconducting fault in a highly seismic zone, the finite difference numerical software is utilized to study the thermal isolation and shock absorption effect of different measures by relying on the heat-conducting fault section works of a newly-built tunnel. The results show that the composite structure of plain concrete lining, the high-damping composite structure of plain concrete and the high-damping composite structure of steel fiber reinforced concrete have almost the same thermal insulation effect, and the high-damping composite structure of plain concrete is slightly better than the other two; in terms of shock absorption, the adoption of the high-damping composite structure of steel fiber reinforced concrete achieves the best effect, and the plain concrete lining has the worst shock absorption effect;compared with plain concrete, the secondary lining structure of the high-damping composite structure of steel fiber reinforced concrete increases the minimum safety coefficient by 28.14%. 2022 Vol. 59 (6): 70-76 [Abstract] ( 449 ) [HTML 1KB] [ PDF 2202KB] ( 506 ) 77 Study on Seismic Resistance of Column-free Atrium Style Subway Station Based on the Integral Response Displacement Method XU Yonghao As a new station structure, the column-free atrium style subway station deletes central columns and set up openings in the middle plate to expand the effective space and increase the efficiency of transfer. To understand the response characteristics of the column-free atrium style subway station with the action of an earthquake, the integral response displacement method suitable for the underground structure with a complex face was used for quasistatic seismic analysis, and the distribution of internal force is compared among large-span column-free atrium style subway stations, general column subway stations and column-free subway stations, all of which have the same face shape. The results show that if the face shape is identical, the axial face, shearing force and bending moment of a large-span column-free atrium style subway station are higher than those of a column-free station and a general column station; the weak position of a column-free atrium style subway station is the connection between the bottom plate and the side walls, and the connection between the middle plate and the side walls is more disadvantageous than traditional subway stations. 2022 Vol. 59 (6): 77-85 [Abstract] ( 536 ) [HTML 1KB] [ PDF 5470KB] ( 464 ) 86 Analysis on the Support Effect of Advance Large Pipe Umbrella at Portal Section of Shallow Tunnel under Unsymmetrical Load SONG Zhanping1,2,3 PEI Jiafeng1,3 PAN Hongwei2,4 SUN Ze1,3 DING Libo5 The reasonable support measures for the portal section of shallow tunnel under asymmetric load are the key to achieving the safe construction of the tunnel portal. The portal section often encounters unfavorable geology such as shallow asymmetric load, strong weathering of mountain surface rock, and soft and broken surrounding rock,so it is necessary to use advance support measures to control the deformation of surrounding rock. The Tbilisi portal project of No. 4 tunnel of Lot F3 of E60 expressway in Georgia under construction is taken as the case to analyze the influence of the ADECO-RS excavation method with or without advance pipe-umbrella support on the ground settlement, extrusion deformation of tunnel face, pre-convergence deformation, convergence deformation, stress distribution of surrounding rock and the development of plastic zone of tunnel portal section by means of the numerical test method. The analysis based on the numerical test results shows that the advance pipe-umbrella support at the tunnel portal section can promote the formation of stress arch, improve the stress of the advance core soil, reduce the ex? trusion deformation of the tunnel face and the plastic zone range of core soil when the ADECO-RS method is used for construction. In the range of about one time tunnel diameter in front of and behind the tunnel face, the tunnel crown settlement rate is the largest, and the deformation amount reaches 85% of the total amount. At the same time,the advance pipe-umbrella support will greatly reduce the plastic zone range of surrounding rock and avoid the overall collapse of the tunnel portal caused by the plastic zone of surrounding rock in the shallow tunnel portal section developing to the surface. 2022 Vol. 59 (6): 86-96 [Abstract] ( 515 ) [HTML 1KB] [ PDF 5009KB] ( 760 ) 97 Study on Stratum Deformation Caused by Large-section Rectangular Pipe Jacking and Jacking Parameter Control XU Hong1 YE Fei2 LIU Qi1 TIAN Liming1 AN Huan1 Based on the pipe jacking works of Wuhan Metro Line 7, a numerical model for ground settlement during jacking construction was established to analyze the relationship between the jacking force and the stratum deformation. The data of earth pressure, thrust and stratum settlement during the construction of different pipe jacking works were compared, and the law of the influence of burial depth and geological conditions on jacking parameters was summarized. The study shows that (1) during pipe jacking, soil disturbance causes ground settlement or uplift and also leads to soil uplift within the range of 2D~4D below the pipe (D is the pipe height); (2) the surface in front of the tunnel face uplifts by the action of additional jacking force, while the soil behind the tunnel face settles by the action of excavation unloading; (3) the uplift peak appears on the ground 1H (H is the burial depth) right in front of the head of pipe-jacking machine, and ground settlement changes quickly within 5 m behind the tunnel face; (4) as the additional jacking force increases, ground settlement right above the head of pipe-jacking machine is reduced, and when the jacking force is greater than 20 000 kN, the variation gradually decreases and the amplitude of variation is relatively small. 2022 Vol. 59 (6): 97-105 [Abstract] ( 427 ) [HTML 1KB] [ PDF 7516KB] ( 578 ) 106 Test Verification of Synchronous Technology Combining Shield Tunnelling with Segment Assembling Based on the Principle of Maximum Pressure Redundancy YUAN Xianghua1,2 ZHU Yanfei1 ZHU Yeting1,2 To greatly improve the shield construction efficiency and reduce the construction cost, a synchronous technology combining shield tunnelling and segment assembling was proposed through the active control of the oil pressures of the shield propulsion system, and a total thrust force control method based on the principle of maximum pressure redundancy was built. Then, the whole system was tested and verified on the large-scale model test platform for synchronous technology combining shield tunnelling and segment assembling. The results showed that the control accuracy of the hydro-cylinder pressures of the shield propulsion system was high, and the total thrust force was controlled within ± 3% of the target value; at the moment of segment assembly, the shield attitudes and propulsion speeds suddenly changed due to the limitation of the response time of the hydro-cylinder pressures, and both would return to the initial values in the full-cylinder propulsion mode; the segment structure had sufficient compressive capacity, and the utilization rate of the compressive strength was only 61.2%. 2022 Vol. 59 (6): 106-113 [Abstract] ( 420 ) [HTML 1KB] [ PDF 4471KB] ( 553 ) 114 Centrifuge Model Test of the Cross Passages in Super Large Diameter Shield Tunnels CHEN Rendong1 LU Ping2 SUN Ye1 LIU Minggao1 PANG Kang1 In order to explore the influence of different buried depths and opening types on the stress and deforma? tion of the main structure when a cross passage is set up between super large diameter shield tunnels, based on the project case of the pedestrian cross passage of the shield section tunnel in Beijing East Sixth Ring Road Reconstruction Project, the stress state, convergence deformation, dislocation between segments and rings and earth pressure around the tunnel opening ring of the shield section tunnel structure are monitored by centrifugal model test to simulate three cases of buried depth, different opening sizes and section types. The results show that: (1) When the centrifugal acceleration reaches the set value, the earth pressure tends to be stable, and the greater the buried depth is,the longer the stabilization time will be required. The soil arching effect exists in the overlying soil of the tunnel, and the greater the buried depth is, the more obvious the soil arching effect will be. (2) The lateral opening of the shield tunnel has a significant impact on the stress of the main structure. The larger the opening size is, the greater the deformation of the structure will be. (3) Under different buried depth cases, the dislocation between segments increases with the increase of centrifugal acceleration, and the increase rate gradually rises. (4) Under different buried depth cases, the stress state on the inside of the main tunnel arch waist is basically the identical, which is compressive stress. The pattern of the stress at the outside of the arch waist is more complex. The compressive stress concentration of the split ring will offset a part of the tensile stress, and the outside of the arch waist of other adjacent rings except the split ring will mainly bear the tensile stress. 2022 Vol. 59 (6): 114-124 [Abstract] ( 441 ) [HTML 1KB] [ PDF 6053KB] ( 504 ) 125 Study on Model Test of Shallow Hard-rock Tunnel Failure Mode by the Action of Overload LIU Quanwei1,2 LIN Wenhao1 LI Weiteng1 QIN Zhe1 FENG Qiang1 YANG Xuxu1 To research the failure mode of the shallow hard-rock tunnel by the action of overload, the study on a large similar model test is conducted on the basis of QY-7+177 monitoring section of The Affiliated Hospital of Qingdao University West Coast District Station of Qingdao Metro Line 6. Unit weight, compressive strength, tensile strength and angle of internal friction are used as the main control parameters of the material to truly reproduce and simulate the physical and mechanical properties of cross-sectional rock mass, and the non-contact strain measurement system is used to observe the process of fissure evolution. A series of inverted V-shaped shear fissures with an included angle of 25°~40° with the crown normal appears during the process of overload, and combined with the Griffith theory of brittle strength, the maximum principal initiation stress of the fissure that first appeared directly above the vault is calculated to be 0.409 MPa, which is 21.6% of the uniaxial compressive strength of similar materials.Test results show that fissures begin to appear on the crown of the surrounding rock of the tunnel even if the stress is relatively low, indicating that it is a hazardous area prone to fissure initiation of the surrounding rock. The failure mode of the surrounding rock of the tunnel is the shear-extrusion failure mode: the arch is subject to shear failure and the rock mass is broken and extruded at the foot of the arch to damage phase coupling. 2022 Vol. 59 (6): 125-131 [Abstract] ( 438 ) [HTML 1KB] [ PDF 4280KB] ( 477 ) 132 Research on the Temperature Distribution Characteristics of Tunnel Fire Based on Distributed Optical Fiber Monitoring LI Zhen1 LENG Xianlun2,3 YIN Qiuyu4 In order to verify the test result of distributed optical fiber monitoring technology in highway tunnel fire, research was conducted on the fire location and fire scale prediction method based on optical fiber monitoring reults, scale physical model test and Pyrosim dynamic simulation were carried out for tunnel fire under natural ventilation, and the formula was proposed for the highest temperature rise of crown and the the longitudinal temperature attenuation pattern of tunnels in case of tunnel fire under natural ventilation. The results show that the crown temperature curve based on distributed optical fiber monitoring is consistent with the thermocouple monitoring curve, and close to the curve obtained by numerical simulation. Distributed optical fiber wide area intensive monitoring is more suitable for early detection of tunnel fire temperature distribution characteristics. Under the natural ventilation, the longitudinal temperature attenuation pattern of the crown is basically a power exponential function in case of tunnel fire, and the temperature tends to be stable after a certain distance from the fire source. The distributed optical fiber is used for long-distance full coverage monitoring without blind area along the tunnel. Combining the formula for the highest temperature rise of the crown and the formula for the longitudinal temperature attenuation pattern, and based on the mutual evidence and inspection between the highly intensive optical fiber measurement results, the vertical and horizontal positions of the fire source can be accurately located, the fire power can be predicted, and the fire scale can be determined. 2022 Vol. 59 (6): 132-139 [Abstract] ( 425 ) [HTML 1KB] [ PDF 2983KB] ( 487 ) 140 Study on the Test of Seismic Performance of Prefabricated Utility Tunnel with a Large Section ZHU Li1 XIAN Jianping1 YUAN Yong2 WANG Hengdong3 MA Huabing4 Based on the urban utility tunnel project of the Start-up Area of Xiong′ an New Area, in order to define the seismic performance of the utility tunnel structure, the low-frequency cyclic loading anti-seismic test was completed on the overall structure model and joint test pieces of the large-section utility tunnel with four compartments,and the computational analysis was carried out of the state of failure and mechanical property of test pieces. The results show that (1) the hysteresis curve of the overall structure is relatively saturated, showing good ductility and energy dissipation capacity, the middle joints have better bending performance, and the ductility of the joints on the edges is worse than that of the middle joints; (2) the skeleton curve of joint test pieces is split into three phases: obvious cracking, yield and ultimate phases, and after the overall structure reaches the ultimate load, the curve is basically close to being horizontal; (3) the stiffness degradation of the overall structure and joint test pieces is continuously uniform throughout the loading process; (4) the structural design of the utility tunnel can ensure seismic performance during normal use. Combined with the stress characteristics and state of failure of test pieces, the structural design of the utility tunnel of the Project is optimized. 2022 Vol. 59 (6): 140-146 [Abstract] ( 384 ) [HTML 1KB] [ PDF 3779KB] ( 518 ) 147 Mechanical Properties of Prefabricated Assembly Utility Tunnel Construction and Field Full-scale Test Study in the Process of Erection of Utility Tunnels SHAN Hongwei1 SUN Mao2 XIAN Jianping2 ZHU Li2 YU Haitao3 In order to solve the problem of inadequate installation accuracy of large tonnage hoisting of prefabricated assembly utility tunnel in Xiong'an New Area, a construction scheme of erecting utility tunnel segment is proposed.By establishing the finite element calculation model of the prefabricated assembly utility tunnel, the mechanical properties of the utility tunnel during the construction of erection are calculated and analyzed, and the calculation results are verified by carrying out the field full-scale model test. The results show that: (1) During the construction of erection of utility tunnels, the performance of the structural material meets the design requirements in the case of lifting under asymmetric load and in the case of lifting through a hole, the maximum tensile stress of structural concrete is less than the tensile strength of the material, and the structure is still in a safe state. (2) During the field test of erection of utility tunnels, stress and deformation results at the key positions of the utility tunnels meet the design requirements. (3) The construction scheme of erection is applicable to long section and large tonnage prefabricated assembly utility tunnels, which can ensure structural safety during construction. 2022 Vol. 59 (6): 147-153 [Abstract] ( 408 ) [HTML 1KB] [ PDF 5167KB] ( 481 ) 154 Field Test Study on the Compaction Effect of Waterstops for Long-section and Large-tonnage Urban Utility Tunnels YANG Zhong1 MA Huabing2 YU Haitao3 XU Hailiang4 YUE Qing5 In order to further improve the waterproof performance of urban utility tunnels, two water stop test schemes were proposed on the premise of ensuring that the boundary conditions conform to the actual project, and the field test study on the compaction effect of waterstop for long-section, full-scale and large-tonnage urban utility tunnel were carried out based on the actual project. The results show that when the tunnel is fully compacted, the tension of the steel strand in test scheme 1 (static splicing + Class I waterstop) is about 90.5% higher than that in test scheme 2 (suspended splicing + Class II waterstop), which has higher requirements for the steel strand tension system; the average width deviation of the tunnel crown and bottom joint in test scheme 2 is only 0.73 mm, which is much smaller than that in test scheme 1, thus contributing to the uniform distribution of the interfacial stress of the waterstop; and the effective interfacial stresses in test scheme 1 and test scheme 2 finally reach 1.61 MPa and 1.56 MPa respectively, and the average joint widths are 7.80 mm and 4.41 mm respectively. It is recommended that test scheme 2 be adopted in the waterproof construction for this utility tunnel project. 2022 Vol. 59 (6): 154-161 [Abstract] ( 457 ) [HTML 1KB] [ PDF 3436KB] ( 472 ) 162 Study on Full-scale Test for Bottom Contact Status of Prefabricated Utility Tunnel Based on Impact Imaging Method MA Huabing1 SHAN Hongwei1 GUO Yawei2 FU Baiyong2 SHANGGUAN Shiqing3 To test the voids between the tunnel bottom and the cushion, the impact imaging method is used for the baseplate tightness test of the prefabricated long-segment and large-tonnage utility tunnel in Xiong'an New Area and the baseplate tightness evaluation indicator suitable for the prefabricated utility tunnel is put forward. The immersion testing was performed to research the influence of immersion in rainwater on the contact status between the tunnel bottom and the leveling course and analyze the influence of the measuring point layout with the impact imaging method on the results of bottom contact status testing. The results show that (1) the impact response strength of 1.79 can be used as the evaluation indicator for the bottom contact status testing of the prefabricated utility tunnel with the impact imaging method, the reliability of judging and identifying the bottom defects can be more than 85%, and the area where any voids on the tunnel bottom exist can be accurately identified; (2) The immersion in rainwater for a short time will cause the whole utility tunnel to sink, make the cushion layer more compact, and improve the contact status of the tunnel bottom; (3) Based on the impact imaging method, the 500 mm×500 mm measuring point layout used in testing the contact status of the utility tunnel bottom has a void identification accuracy that can meet the demands for engineering applications, as well as a higher testing efficiency. 2022 Vol. 59 (6): 162-169 [Abstract] ( 444 ) [HTML 1KB] [ PDF 6359KB] ( 464 ) 170 Application of Self-sensing Steel Strand with Built-in Optical Fiber in Assembly of Prefabricated Utility Tunnels ZHANG Yaodong1 LI Pengfei1 LI Qiangzhan2 FU Baiyong3 GUO Yawei3 The assembling process of prefabricated utility tunnels mainly depends on the tensioning and locking of prestressed steel strands to make pipe joints assembled in place. In the process of assembly and tensioning, whether the synchronization of tensioning is favorable and whether the joint tension is caused relaxed in the operation phase of the utility tunnel transport vehicle will produce a direct effect on the waterproof performance of the water stop joint of the utility tunnel joint. In order to explore the tensioning synchronization and prestress loss of steel strands in the process of utility tunnel assembly, the self-sensing steel strands with built-in optical fiber are used to conduct real-time monitoring of the tensioning process of utility tunnel assembly, verify the feasibility of intelligent steel strands used for tensioning monitoring, and analyze and evaluate the synchronization performance of the tensioning process and the degree of prestress loss. This method can provide technical support for the performance evaluation of the assembly and tensioning process of the long segment and large tonnage prefabricated utility tunnel. 2022 Vol. 59 (6): 170-176 [Abstract] ( 417 ) [HTML 1KB] [ PDF 3999KB] ( 541 ) 177 Study and Application of Key Technical Parameters of Pre-grouting in High-pressure Water-rich Deep Shaft Face ZHANG Minqing1 XIN Weike1 JIA Dapeng1 SI Jingzhao2 WANG Huanlong3 In the shaft construction of the Gaoligongshan Tunnel, the maximum water inrush of a single advanced geologic exploration borehole is 126.9 m3/h, and the pre-grouting technology is used on the faces for grouting reinforcement and water blocking. A total of 12 pre-grouting cycles were conducted for the main shaft face and 11 pregrouting cycles were conducted for the auxiliary shaft face. The results of application show that (1) the face pregrouting method is employed to effectively solve the difficulties in grouting reinforcement and water blocking technologies for high-pressure water-rich deep shafts and ensure safe and normal construction of shafts; (2) it is appropriate to use 10 m3/h as the reference value of water inrush control during the normal construction of shafts. When the face water inrush is equal to or greater than 10 m3/h, grouting and water blocking measures shall be taken; (3) before the excavation of shafts, it is better to use 1.4 L/(min·m) as the reference value of water inrush control of a single advanced exploration borehole. When the length of an advanced exploration borehole cycle is 60 m, the reference value is 5.0 m3/h; (4) for the pre-grouting in the shaft face, it is better to use 1.0 L/(min·m) as the reference value of water inrush control of an inspection hole. When the length of a grouting cycle is 60 m, the reference value is 3.6 m3/h;(5) based on the water inrush of an inspection hole, grouting and water blocking rate, water inrush of a shaft during excavation, and efficiency of well completion, 60 m should be used as the length of a cyclic grouting section when pre-grouting is conducted in the shaft face. 2022 Vol. 59 (6): 177-186 [Abstract] ( 463 ) [HTML 1KB] [ PDF 2472KB] ( 677 ) 187 Study on Grouting Reinforcement Range of Shield Tunnel Undercrossing Expressway in Composite Stratum LIU Bin1 ZHAO Dongping2, 3 LI Dong3 When the shield tunnel in the sandy gravel mudstone composite stratum under-crosses the expressway, it is easy to cause a large settlement of the expressway pavement above. In order to ensure the safety and the comfort of driving on the expressway, grouting in the tunnel is widely used on the site to reinforce the soil around the tunnel, so as to control the land subsidence. Therefore, it is very important to study the grouting reinforcement range in the tunnel when the shield tunnel in the sandy gravel mudstone composite stratum under-crosses the expressway. By taking the tunnel of the Gaobeiba entrance-exit section of Chengdu Rail Transit Line 30 as the research case, the grouting reinforcement range when the shield tunnel under-crosses the expressway under different stratum composite ratios is studied by using the three-dimensional numerical calculation method. By taking land subsidence as the main evaluation indicator, the effects of various reinforcement schemes under different stratum composite ratios are compared and demonstrated, and the numerical calculation results are compared and analyzed with the field measured data. The results show that: (1) The stratum composite ratio has a significant influence on the maximum value of land subsidence, the range of subsidence influence and the manifestation form of the subsidence curve; (2) Land subsidence amount caused by shield tunneling is negatively correlated with the stratum composite ratio β, but not obviously correlated with the surface uplift amount; (3) When the stratum composite ratio β is determined, from the point of view of controlling land subsidence, the effect of increasing the radial reinforcement depth of the stratum is better than that of expanding the circumferential reinforcement angle. 2022 Vol. 59 (6): 187-196 [Abstract] ( 445 ) [HTML 1KB] [ PDF 5592KB] ( 554 ) 197 Analysis on the Construction Hazard Causes of Tunnels with Altitude Difference in the Tilted Soft-hard Interbedded Stratum LIU Zonghan1,2 HAN Fenglei1,2 ZHANG Xuefu1,2 LI Hongliang3 QIN Zhen1,2 ZHAO Yicong1,2 To solve the construction hazards of tunnels with altitude difference under construction in Guizhou, such as large deformation of surrounding rock and lining cracks, field investigation and numerical simulation are used to research the mechanical response to tunnel construction in the tilted soft-hard interbedded stratum and its hazard causes, and the treatment methods are put forward. The results show that the main geological factors causing tunnel cracking include soft-hard interbedded stratum and topographical changes. Cracking in the crown area is more affected by tilted soft-hard interbedded strata, and the extent of damage to the invert area is more affected by the construction of subsequent driving tunnel; from the steep area at the entrance to the flat area at the exit, the stress and displacement of advanced tunnel are gradually reduced, and the maximum differences are 4.34 MPa and 38.89 mm,respectively. The lining cracking of the advanced tunnel occurs on the left side of the crown, on the left shoulder and at the backfilling of the invert, and the subsequent driving tunnel separately increases the stress on these three locations by 29.84%, 54.58% and 130.61%; the high-gradient tilted strata increase the shear slip between rock formations so that the tunnel deflects to the bottom right, and if the absolute displacement is too large, it will cause uneven deformation of various locations, resulting in asymmetric damage to the tunnel structure; attention should be paid to the following problems during the tunnel construction in a tilted soft-hard interbedded stratum: insufficient bearing capacity of the advanced tunnel base, large deformation of surrounding rock, etc., and the methods, such as full-face grouting, temporary invert and root piles made of steel tubes, can effectively prevent cracking. 2022 Vol. 59 (6): 197-207 [Abstract] ( 387 ) [HTML 1KB] [ PDF 6015KB] ( 555 ) 208 Posture Destabilization and Treatment Measures of Large Diameter Shield in Soft Mudstone ZHOU Shengli In order to solve the "rolling" and "cutterhead pitch" problems encountered by a large diameter shield machine in the process of tunnelling in the curved section of the soft mudstone composite stratum, by analyzing the causes for the attitude destabilization of the shield tunnelling, the commonly used methods in the deviation correction and the corresponding correction principles, the effects of various correction measures are analyzed in combination with the actual correction process on site, and the posture correction technology applicable to the rolling destabilization of the shield. The results show that: (1) When the shield tunnelling is implemented in the soft and hard composite stratum, the complex changes of the stratum environment will easily lead to the instability of the shield posture, and the tunnelling in the long curve section will aggravate the instability; (2) Such corrective measures as adding radial oil cylinder, one-way rotation of shield cutterhead, and adding steel wedge are helpful to improve shield rolling. Adjusting the pressure of the oil cylinder, adding longitudinal oil cylinder and secondary grouting behind the wall are helpful to the adjustment of the shield from "cutterhead pitch"; (3) Auxiliary schemes such as grease and bentonite injection, tool change and butter application are conducive to reducing the constraint of the shield during posture adjustment; (4) For the case similar to the simultaneous instability of "cutterhead pitch" and "rolling" of the shield, it is recommended to first solve the rolling correction of the shield before the problem of axis shifting. 2022 Vol. 59 (6): 208-215 [Abstract] ( 442 ) [HTML 1KB] [ PDF 5068KB] ( 557 ) 216 Research on Zonal Dust Removal Technology in Tunnel Construction Period Based on Fuzzy Control LI Penghui1 LI Ke1,2 WANG Fang1 CHENG Liang1,2 JI Hongwei2 For the problems related to the lack of alternatives for dust removal means and low dust removal efficiency in the tunnel automatic dust removal system, a new method of zonal dust removal based on fuzzy theory is proposed,and a zonal dust removal system is established by combining fuzzy PID control technology. The system uses the sampling module to monitor the data in real time, corrects the parameters online through the fuzzy control module, and continuously circulates the control frequency converter to improve the operating frequency of the controlled object,to adjust the ventilation and spray volume of each operation area. Finally, the treatment module realizes the purpose of coordinated dust removal by ventilation and water curtain dust fall. The system is applied to a high-altitude super-long tunnel in Tibet. The results show that the system can reduce the dust concentration in the tunnel face, inverts and secondary lining operation area, with the average concentration reduced by 78.60%, 78.90% and 80.00% respectively. With a high dust removal efficiency, the system can effectively protect the physical and mental health of tunnel construction workers, and improve the tunnel construction efficiency. 2022 Vol. 59 (6): 216-223 [Abstract] ( 391 ) [HTML 1KB] [ PDF 3917KB] ( 462 ) 224 Study and Application of Section Survey Technique of CPⅡ Network in Long and Large Tunnel ZHANG Yanping In order to ensure the overlapping accuracy of the section CPⅡnetwork in the tunnel before breakthrough of the long and large tunnel, and improve the construction efficiency of the ballastless track, by taking the Anding tunnel on the Yuxi-Mohan railway as an example, the section survey technique of the CPⅡ control network in the tunnel before breakthrough of the long and large tunnel under complex conditions was studied, and a CPⅡnetwork survey 0method in the tunnel by using a crossing traverse network plus the free stationing was proposed. By strengthening the network shape strength and the accuracy of CPⅠ control network outside the tunnel and CPⅡ control network inside the tunnel, optimizing the distribution of CPⅡ points inside the tunnel and the adjustment calculation scheme, the compatibility of the construction traverse points under joint survey was analyzed, and a complete set of section survey technique of CPⅡ network inside the tunnel before breakthrough of the long and large tunnel was presented. The results show that the section survey method can not only ensure the accuracy of the CPⅡcontrol network in the tunnel, but also ensure the overlapping accuracy between the CPⅡ control networks surveyed section in the tunnel, it can also ensure the smooth overlapping of each section of ballastless track after the breakthrough of the tunnel. 2022 Vol. 59 (6): 224-231 [Abstract] ( 353 ) [HTML 1KB] [ PDF 3258KB] ( 494 ) 232 Standard for Design of Early High-strength Shotcrete for Railway Tunnels and Application Research LIU Zhe1,2 JIANG Yanhong3 YANG Yang4 Early high strength shotcrete is characterized by rapidly forming tensile and shear strength during con? struction, which can improve the stability of surrounding rock and ensure safe and efficient operation. It has been widely used in foreign engineering practices, and relevant systematic technical standards have been formed. Although the early strength of shotcrete received attention relatively late in China, at present, it has been gradually popularized and applied in domestic building, highway, railway and other industries. More emphasis has been paid on the strength requirements within 24 hours in the railway industry. In recent years, field tests and applications have shown that the early strength of shotcrete can meet relevant requirements. Moreover, although the cost of early high-strength shotcrete is slightly higher than that of ordinary shotcrete, it has significant advantages over the ordinary shotcrete when taking into consideration such factors as material loss, work efficiency, quality and safety. 2022 Vol. 59 (6): 232-238 [Abstract] ( 406 ) [HTML 1KB] [ PDF 894KB] ( 885 ) 239 Analysis on Durability Degradation of Concrete under Multiple-factor Coupling Effect in Complex Environment XU Wensheng1 WU Xianguo2 FENG Zongbao2 QIN Yawei1，2 CAO Yuan2 LIU Pengcheng2 In order to study the deterioration mechanism of concrete durability under complex multi-factor condi? tions, relying on a major tunnel project case in the alpine region and considering the interaction of multiple factors,the accelerated laboratory test method is used to study and analyze the influence of salt intrusion, freeze-thaw cycles, carbonization alternation and their coupling effects on concrete durability based on orthogonal tests. The freeze-thaw damage, composite salt erosion, strength failure and carbonization erosion caused by different environments are analyzed to reveal the complex coupling conditions and the synergistic effects of additives and admixtures on the deterioration of concrete durability. The results show that the alternating cycle of salt intrusion, freeze-thaw and carbonization can temporarily reduce the capillary porosity of concrete, and this alternating cycle case will cause a greater loss of compressive strength, and the combined salt erosion has a certain degree of inhibition on the carbonization depth of concrete. The influence of fly ash content between 10% and 20% and air entraining agent content between 0.8% and 1.2% on concrete durability is relatively stable. 2022 Vol. 59 (6): 239-249 [Abstract] ( 397 ) [HTML 1KB] [ PDF 5991KB] ( 629 ) 250 Application Research on the Bionic Self-healing Technology for Secondary Lining Concrete of Tunnels CAO Yan1 WANG Ruiwen1,2 ZHAO Weiwei2 SHI Qibin3 PAN Xuhui3 OU Dingfu1,2 To reduce the secondary lining concrete cracks of the tunnel during the operating period, preventive mea? sures shall be taken during construction, and the crack self-healing technology is an effective method to achieve this goal. Through comparison with the technologies such as shape-memory alloy (SMA) method, hollow-core optical fiber and hollow-core fiber method, microbial mineralization method and capsule-based coating self-healing technique, it is concluded that the microcapsule-based coating self-healing technology has the following advantages:easy concrete mixing, even distribution of capsules, rapid response to cracks and long-term sustainability. This technology has been applied to the construction of Liyang Jiaoweiqin Tourist Complex Tunnel, in which self-healing capsule materials have been tested and detected and the anti-cracking effect and self-healing capacity of concrete mixed with microcapsules have been traced and observed. The research shows that the self-healing capacity of the secondary lining concrete mixed with microcapsules is extremely strong. With stress sensitivity, high bond strength and permeability, the self-healing agent can obviously reduce the width of cracks on 7 d after cracks occur, and cracks can be basically healed on 21 d and completely healed on 28 d. 2022 Vol. 59 (6): 250-257 [Abstract] ( 429 ) [HTML 1KB] [ PDF 2264KB] ( 564 ) 258 Test and Study on the Application of Synthetic Macro-fibers in the Segements of Drainage and Storage Tunnels Built by Shield Method GUAN Linxing1 WEN Zhuyin1 WANG Xiaopeng2 YOU Guangming1 SUN Wei1 ZHUANG Qianwei3 In order to alleviate the adverse effect of water pressure in the drainage and storage shield tunnel, it is proposed to add synthetic macro-fiber into the tunnel segment considering that the internal medium of the tunnel is rainwater and sewage. Through material mechanical properties and straight beam loading tests, the application effect of synthetic macro-fiber in drainage and storage tunnel segments is studied. The results show that, compared with the mechanical parameters of plain concrete, the compressive strength, flexural strength and elastic modulus of fiber reinforced concrete are reduced by 1.8%, 7% and 4% respectively, and the addition of fiber will reduce the mechanical properties of concrete. After the concrete cracks, the reinforcement stress of PPF1 (synthetic macro-fiber 1),PPF2 (synthetic macro-fiber 2) and SF (steel fiber) specimens decreases by 2%, 10% and 17% respectively compared with that of ordinary concrete. The fiber shares part of the tensile stress of the reinforcement, reflecting the advantages of fiber reinforced concrete. From the distribution pattern, the cracks of ordinary reinforced concrete are"sparse and wide", and the maximum crack width at the end of the test is 0.55 mm; the cracks of synthetic fiber reinforced concrete are "dense and narrow", and the maximum crack width at the end of the test is 0.3 mm. After the concrete cracks, the fiber reduces the width of the crack, and the addition of fiber is beneficial to the crack control of the tunnel lining structure. 2022 Vol. 59 (6): 258-265 [Abstract] ( 464 ) [HTML 1KB] [ PDF 4058KB] ( 473 )

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