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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2021 Vol.58 Issue.6 Published 2021-12-25 1 Progresses and Challenges in Research on Parallel Double-tube Tunnels Crossing Landslides FENG Jimeng1,2 JIANG Hui1,2 DING Xiaoqi1,2 YU Longping1,2 ZHANG Junru1,2 In this paper, the typical engineering cases of double-tube tunnels crossing landslides at home and abroad are summarized, and the research progresses in the mechanism of landslide instability induced by tunnel excavation, tunnel response characteristics under the influence of landslide, landslide monitoring and prediction technologies, treatment technologies of tunnel-landslide system and so on are described and analyzed in detail. Then,five current major problems faced by the parallel double-tube tunnel works crossing landslide are put forward,namely, evolution process of landslide instability, landslide stability, tunnel structure response characteristics, landslide instability prevention and control technology and intelligent monitoring technology of landslide deformation. In-view of current challenges faced by parallel double-tube tunnels crossing landslides, it is pointed out that refined numerical simulation, combined innovation of landslide anchorage system and materials, new tunnel support system and air-ground integration based intelligent landslide monitoring technology would be important research directions in the future. 2021 Vol. 58 (6): 1-10 [Abstract] ( 695 ) [HTML 1KB] [ PDF 1736KB] ( 1378 ) 11 Review of Researches on Groundwater Seepage Induced Crystallization and Blockage Mechanism and Scale Inhibition Technology in the Tunnel Drainage System in Karst Areas LU Guannan1 WANG Peng1 YANG Yun2 MAO Chengjun3 WU Yongjing4 WU Jianfeng3 In karst areas, groundwater seepage induced crystallization and blockage in the tunnel drainage pipe may result in poor tunnel drainage, erosion of tunnel lining, destruction of support structure, tunnel deformation, water gushing, collapse and other engineering accidents. Therefore, it is necessary to study the mechanism of groundwater seepage induced crystallization and blockage in the drainage system in karst tunnels to provide guarantee for early identification and safety evaluation of geological disasters in karst tunnels. Based on the investigation of a large number of literatures, this paper comprehensively analyzes the research results of domestic and foreign scholars in terms of chemical dissolution-crystallization mechanism of soluble rocks. Meanwhile, based on the self-established ideal numerical model of crystallization and blockage in the tunnel drainage pipe, the crystallization-blockage process of the drainage pipe and its influencing factors are analyzed to probe into possible scale inhibition measures. Fi? nally, the following conclusions are obtained: (1) micro factors affecting the crystallization and blockage in karst tunnels include CO2 partial pressure, pH value, temperature, stress field, hydrodynamic force and Ca2+ concentration,etc. and under conditions of the low temperature, low concentration, low flow rate, acidic environment and low CO2 partial pressure it is conducive to reducing crystallization precipitation in the tunnel; (2) at present, the quantitative research on crystallization and blockage of the drainage pipe in karst tunnels is weak, and the hydrodynamics-chemical reaction coupled crystallization process is not considered in the empirical formulae and classical theories. According to the research status of this scientific problem, it is required in the following to focus on the large-scale indoor crystallization test research, establish a model test system to truly simulate the actual groundwater seepage induced crystallization and blockage process in tunnels, and develop a numerical model of karst crystallization process in the drainage pipe under hydrodynamic conditions, so as to realize the quantitative characterization and accurate prevention and control of tunnel drainage pipe blockage process under the site scale. 2021 Vol. 58 (6): 11-20 [Abstract] ( 784 ) [HTML 1KB] [ PDF 2619KB] ( 1354 ) 21 Effect of Cold Water Mixing Modes on Prediction of High Geo-temperature Induced Heat Hazards in Tunnelling in South Tibet FU Lei MA Xin SHAO Wei Layue tunnel is located on Sichuan-Tibet railway, it is prone to high geo-temperature induced heat haz? ards. So, hydrochemical and isotopic analysis is carried out for Changqing, Pailong and Layue hot springs, which are closely related to the tunnel. It is found that the above hot springs are formed by different causes and all mixed with cold water. Among the others, the mixing ratio of cold water in Layue hot spring is as high as 91%. Considering the effect of cold water mixing on the prediction of high geo-temperature induced heat hazards in the tunnel, two mixing modes of cold water in hot-spring are put forward. In the mixing mode of shallow cold water with hot water, the mixing zone of cold and hot water is generally close to or higher than the elevation of the hot spring point. So, the heat hazard risk induced by high geo-temperature would be greater when a tunnel is built below the elevation of the hot spring point. In the mixing mode of hot water and confined cold water, the mixing zone of cold and hot water is generally located in the confined cold water aquifer, lower than the elevation of the hot spring point. The heat hazard risk induced by high geo-temperature would be smaller when a tunnel is built above the elevation of the hot spring point.According to the landform, geological structure, hot springs, boreholes and other geological information, it is inferred that the hot springs in the studied area are the mixing mode of hot water and shallow cold water. Based on the above viewpoint, the high geo-temperature induced heat hazards are predicted for the Layue tunnel and it is determined that there are 6 sections with high geo-temperature induced heat hazard risks. Among them, the section ① ~ ④might have higher heat hazards, and section ⑥ should be further researched to determine the degree of the heat hazard. 2021 Vol. 58 (6): 21-30 [Abstract] ( 769 ) [HTML 1KB] [ PDF 5432KB] ( 707 ) 31 Analysis on Land Surface Geothermal Spatial Distribution Characteristics of Long and Deep Tunnels Based on Landsat 8 Remote Sensing Images: A Case Study of Gaoligongshan Tunnel HUA Xiaoming LUO Chenxi GOU Xiaojun ZHANG Haichao Taking Gaoligong Mountain Area as the study area, this paper is focused on quickly obtaining the spatial distribution characteristics of land surface temperature of long and deep tunnels. According to the Landsat 8 remote sensing images of the study area, the radiative transfer equation method is adopted to perform land surface temperature inversion, which is then compared with the results of single channel algorithm. The results show that: (1) the remote sensing method could be used to quickly and effectively obtain the land surface temperature in the study area,the geothermal spatial distribution conditions are consistent with the fault distribution and exposed hot spring distribution conditions revealed by the existing geological survey, and the ground temperature results obtained by two algorithms are relatively consistent; (2) in the study area, the geothermal resources are mainly distributed in Nujiang River Valley and Luxi-Zhefang Basin, and sporadic high-temperature reactions appear in some mountain areas. In Nujiang River Valley, the geothermal resources are distributed in a north-south belt along Nujiang Fault Zone,which is mainly governed by many deep and large faults in Gaoligong Mountain Area. In Luxi-Zhefang Basin, the geothermal resources are generally distributed in a strip from south-north to north-east in the middle of the basin and mainly governed by the Longling-Ruili Fault and the Basin topographies; (3) the different influences of solar ra? diation on sunny and shady slopes should be considered when the remote sensing method is used to explore geothermal distribution in complex mountain areas. 2021 Vol. 58 (6): 31-37 [Abstract] ( 628 ) [HTML 1KB] [ PDF 3631KB] ( 683 ) 38 Study on Relationship between Relative Maximum Oxygen Uptake and Personnel Evacuation Capacity Based on the Step Test WANG Mingnian1,2 CUI Peng1,2 YU Li1,2 LU Xudong3 HU Xiaoyue1,2 XIA Pengxi1,2 The relationship between relative maximum oxygen uptake and personnel evacuation exercise ability is obtained according to the completion time of different subjects in the 500 m evacuation test and in combination with the relative maximum oxygen uptake in the step test. The subjects participating in the test are between 20 and 25 years old and a total of 13 subjects are selected for the step test and evacuation test, respectively. In the step test,physiological parameters, e.g. blood oxygen saturation and heart rate of the subjects at different stages, are tested and the relative comprehensive heart rate is proposed to evaluate the exercise ability. The maximum oxygen uptake of the subjects is indirectly converted by the A-R nomogram method, and the relative maximum oxygen uptake is used to eliminate individual differences. 48 hours after the step test, the same subjects are asked to conduct a 500 m evacuation test, of which the completion time is recorded accordingly. Then, the fitting analysis is carried out for relative maximum oxygen uptake obtained from the step test and completion time of the evacuation test. It is found that there is an inverse relationship between the completion time of the evacuation test and the relative maximum oxygen uptake. So, the relative maximum oxygen uptake can be used to indirectly express the evacuation exercise ability. 2021 Vol. 58 (6): 38-45 [Abstract] ( 642 ) [HTML 1KB] [ PDF 2419KB] ( 1089 ) 46 Study on the Partition Mode of Prefabricated and Assembled Secondary Lining of Double-track Railway Tunnels by Drilling and Blasting Method ZHOU Xiaojun1 GUO Jian1 YANG Changyu2 QING Weichen2 XIONG Guoxing2 KUANG Wentao2 When the cast-in-situ concrete is used for the tunnel secondary lining constructed by the drilling and blasting method, the construction speed is slow and the arch lining quality is difficult to meet the design requirements. So a partition scheme of prefabricated and assembled secondary lining structure is proposed for the doubletrack railway tunnels constructed by the drilling and blasting method. The stiffness values of transverse and longitudinal joints of prefabricated and assembled secondary lining are calculated on the basis of the calculation theory on segment joints of shield tunnels. Then, the beam-spring calculation model is used to compare and analyze different lining partition schemes, study the stress characteristics of prefabricated and assembled lining with different thickness and determine that the optimal thickness of prefabricated and assembled secondary lining is 500 mm. Meanwhile, the shell-spring calculation model is adopted to analyze the internal force distribution of prefabricated and assembled secondary lining with straight joints and different widths. The results show that the internal force distribution of prefabricated and assembled secondary lining has obvious three-dimensional characteristics, the bending moment is large at the edge of the joint, but small in the middle, and the width of prefabricated and assembled secondary lining should be 2.0 m. 2021 Vol. 58 (6): 46-58 [Abstract] ( 700 ) [HTML 1KB] [ PDF 2517KB] ( 1268 ) 59 Numerical Simulation Study on Whole Construction Process of Vertical Pipe Jacking WEI Gang1 HAO Wei2 WEI Xinjiang1 WANG Xiao2 ZHANG Shuyuan2 In order to analyze the impact of vertical pipe jacking on the surrounding environment during the pro? cess of upward jacking from the utility tunnel, this paper uses the Midas GTS NX software to establish the model and simulate the vertical pipe jacking construction process by changing the material parameters of the model as well as activating and passivating the corresponding mesh. And then the effects on pipe jacking induced by different soil conditions, construction parameters, pipe diameters and groundwater depths are studied and compared with the model test data. The results show that the surface soils first settle and then heave in the range of -1D~1D (D is the diameter of vertical jacking pipe) along with the vertical pipe jacking, and the maximum heaving value is 4.13 mm; the utility tunnel settlement increases gradually and is up to 3.44 mm at most; the worse the soil condition, the greater the disturbance to the soils and utility tunnel due to the upward jacking, and the existence of groundwater makes the surface heaving phenomenon disappear in the range of -1D~1D; different construction parameters have different effects on pipe jacking, the change of front thrust and pipe diameter has a little effect on pipe jacking, while the change of friction coefficient has a great effect on vertical displacements of soils and utility tunnel; the variation law of surface soil displacement measured by the model test is consistent with the numerical simulation results. 2021 Vol. 58 (6): 59-67 [Abstract] ( 741 ) [HTML 1KB] [ PDF 3043KB] ( 1122 ) 68 Superposition Principle Based Numerical Estimation Method of Jacking Force of Vertical Curved Jacking Pipes with Large Rectangular Section XIAO Zunqun1,2,3 CAO Tongtong1 XU Caiyun1 YANG Kai2 DONG Qiongying1 JIANG Yinan1 The jacking pipes are divided into several sections according to the slopes of vertical curved jacking pipes with large rectangular section. Based on the displacement control method, the finite element analysis model is established for each section, and the mechanical relationship among the models is set up by setting the initial boundary conditions. The stress field of jacking pipes and surrounding rocks is obtained by applying a displacement value as a pipe length to the initial section of pipe jacking at different jacking positions, and then the jacking force and lateral resistance at each jacking position in each model are calculated. The jacking force and lateral resistance calculated as per the corresponding numerical models are properly superimposed to obtain the fitting relationship between the jacking force and the jacking distance in the whole vertical curved pipe jacking. The calculation results show that the lateral friction coefficient and pipe-soil contact range during shallow pipe jacking are closely related to the properties of the soil layer. In the sandy soil layer, the resistance-reducing slurry is easy to leak and it is diffi? cult to form a stable mud screen around jacking pipes. In this context, the pipes are usually in full contact with soils,of which the lateral friction coefficient can reach 0.4. The fitting formula regarding the relationship between the jack?ing force and the jacking distance obtained under this calculation condition can be used as the general formula for calculating the jacking force of shallow-buried vertical-curved rectangular pipe jacking under the same construction conditions. 2021 Vol. 58 (6): 68-76 [Abstract] ( 742 ) [HTML 1KB] [ PDF 2254KB] ( 644 ) 77 Analysis on Influence of Penetration Angle on Disc Cutter Impact Based on Three-dimensional RBD-DEM Coupling Method XU Gongyun1 XU Wanghao1,2 YAO Zhigang1 FANG Yong1 LIU Sijin3 In the soft-hard composite stratum, shield tunnelling may easily induce such problems as eccentric wear and fracture of disc cutters, so that the replacement frequency of cutter tools may increase largely. Therefore,considering the interaction between the disc cutter and strata based on RBD (rigid body dynamics)-DEM coupling method, the EDEM discrete element software is adopted to realize the passive motion of disc cutters in numerical simulation. Six working conditions with intersection angles of 15°, 30°, 45°, 60°, 75° and 90° are established to study the effect of changing penetration angles on impact of disc cutters in the soft-hard composite stratum. The results indicate that the penetration angle mainly affects the normal load on the tangential and normal planes. When the penetration angle is up to 45°, the peak load on the tangential and normal planes of the disc cutters might reach the maximum in the impact phase. When the penetration angle changes from 90° to 45°, the increase amplitude of peak normal load on normal and tangential planes might reach 18.74 times and 3.53 times, respectively. The abrupt change of normal load on normal plane is the main cause of falling off, offset and fracture of the disc cutter. 2021 Vol. 58 (6): 77-84 [Abstract] ( 698 ) [HTML 1KB] [ PDF 3282KB] ( 620 ) 85 Assessment of Large Deformation Risk in Soft Rock Tunnels Based on Game Theory - Cloud Model HE Leping1 XU Yingdong1 HU Qijun1 CAI Qijie2 It is easy for soft rock tunnels to have obvious large deformation characteristics under the combined ac? tion of geology, hydrology, engineering and other factors. At present, the studies have begun to take shape in terms of the mechanism of large deformation and the optimization of support structures in soft rock tunnels, while the studies on risk assessment and control of large deformation disasters are still in its infancy. Regarding the risk assessment of large deformation in soft rock tunnels, there is no systematic risk assessment index system on one hand and the risk assessment indices are random and fuzzy on the other hand. Based on comprehensive analysis of influence factors of large deformation risks in soft rock tunnels, 15 evaluation indices and corresponding classification standards are proposed in this paper, so that the large deformation risks in soft rock tunnels are divided into four levels. Then, in combination with the standardization process and G1-CRITIC method, the subjective and objective weights are obtained by ideological optimization based on of the game theory, and a new cloud model-based comprehensive risk assessment method is put forward. Finally, the proposed multi-factor comprehensive risk assessment method is applied to assessment of the large deformation risks in Daliangshan No. 1 tunnel on Leshan-Xichang expressway, of which the assessment results are basically consistent with the field construction situation, providing a new idea for quantitative evaluation of surrounding rock stability in soft rock tunnels. 2021 Vol. 58 (6): 85-94 [Abstract] ( 685 ) [HTML 1KB] [ PDF 1750KB] ( 1101 ) 95 A Calculation Method of Surrounding Rock Pressure of Shallow-buried Loess Tunnels under Considering Ground Cracking LAI Hongpeng1 WANG Bin1 LIU Yuyang2 The influence of ground surface tension cracks on surrounding rock pressure of shallow-buried loess tunnels is not considered in the current tunnel design code. The paper first summarizes the deformation characteristics of surrounding rocks and the composition characteristics of failure slip plane in shallow-buried loess tunnels,then it constructs the calculation model of surrounding rock pressure based on the limit equilibrium theory, deduces the calculation formulas of tension cracking depth and tunnel surrounding rock pressure, and discusses the relationship between calculation results and influencing parameters, and finally, by comparing with the measured data and the existing theoretical calculation results, it proves the rationality of the calculation method. The research results show that due to the existence of ground surface tension cracks, both the normal stress and shear stress on the inclined shear plane in the soil mass would increase compared with that without considering surface tensile cracks, the fracture plane would share more loads generated by the overlying soil masses, and the surrounding rock pressure of the shallow-buried loess tunnel would be significantly reduced. The calculation curve of surrounding rock pressures in the proposed new model presents a form of parabola changing with the increase of buried depth, and the peak value of the curve can provide a reference for the demarcation of deep or shallow buried depth of a tunnel. Compared with the traditional methods, the calculation results of the new model are closer to the measured values. 2021 Vol. 58 (6): 95-101 [Abstract] ( 665 ) [HTML 1KB] [ PDF 1961KB] ( 906 ) 102 Analysis on Shear Deformation in a Circular Tunnel Based on Optimized Neural Network HUANG Diwen HUO Hongbin CHEN Dong A circular tunnel is prone to elliptical deformation under the impact of seismic shear wave. Main meth? ods for evaluating the deformation are analytical solution and numerical simulation. So, in this paper, a new method based on optimized neural network is proposed to accurately predict the elliptical deformation through the constructed algorithm model. In the first part of this paper, the back propagation neural network (BPNN) optimized by mind evolutionary algorithm (MEA) is adopted to determine the elliptical deformation ΔD of the circular tunnel lining.Then, a sample database containing 370 data sets is collected from the existing literatures and numerical analysis examples. The numerical analysis is in line with the assumption of the existing analytical solutions, and the data collected from the literatures include the measured results on the site. Since not considered in most analytical solutions, the interface strength Rinter and buried depth h are introduced as additional input parameters. The values of three statistical performance indexes R2, MAPE and RMSE indicate that the improved BPNN has good generalization performance. In the second part, the mean impact value (MIV) algorithm is used to analyze the impact of parameters in the trained network. The calculation results reflect the correlation between input parameters and output ones, and the prediction results are in good agreement with that of analytical solutions and numerical analysis. 2021 Vol. 58 (6): 102-110 [Abstract] ( 543 ) [HTML 1KB] [ PDF 2463KB] ( 705 ) 111 Time-dependent Reliability Analysis of Shield Tunnel Structure under Corrosion Conditions of Segment Rebars and Bolts ZHANG Dongmei1,2 CHEN Congcen2 As for the uncertainty of the influence of corrosion of segment rebars and joint bolts on the structural be? haviors of shield tunnels, the uncertainty relationship between the material corrosion depth and the time is established by using a Gamma random process model on the basis of the measured corrosion data. In the ABAQUS software, the calculation process of tunnel structure reliability is established by using Python language to analyze the structural reliability of shield tunnels under different corrosion conditions of rebars and bolts, and the time-dependent variation laws of failure probability of tunnel structure are obtained under ultimate limit state and serviceability limit state. The study results show that once the rebars and bolts are rusted, the failure probability of the tunnel structure would reach a higher level under the common corrosion rate of 20%~30% in the whole life cycle of the tunnel, of which more than 30% bolt corrosion rate might make the failure probability of the bearing capacity on the joint section close to 100%. The failure probability of a lining ring of the tunnel structure is significantly affected by bolt corrosion, and rebar corrosion might also have a great impact on the bearing capacity and stiffness of segments. 2021 Vol. 58 (6): 111-120 [Abstract] ( 661 ) [HTML 1KB] [ PDF 2927KB] ( 1023 ) 121 Analysis of the Deformation and Structural Stress of a Metro Station Constructed by Pile-Beam-Arch Method ZHOU Wendi1,2 LIANG Qingguo1,2 ZHANG Jindong3 As a new construction method of metro stations, the Pile-Beam-Arch method (PBA) has been success? fully applied in the practical engineering, but there is a lack of comprehensive researches on the surface settlement and structural stress of metro stations caused by PBA method construction. Taking a metro station constructed by Pile-Beam-Arch (PBA) method as the engineering background, this paper analyzes the surface settlement and the structural stress of the metro station in different construction stages of PBA top-down construction method, by means of the combination of numerical simulation with on-site monitoring. The research results show that the excavation of the pilot tunnel and the construction of the supporting arch have great disturbance to the ground, it is necessary to pre-reinforce the ground (such as advance pipe-roof + grouting), so as to strictly control the total amount of ground settlement. The time-history curve of the axial force of retaining piles can be divided into three stages: rapid growth stage, slow growth stage, and stable stage. The variation laws of measured and the calculated settlements are basically consistent, and both the measured and calculated maximum surface settlement occur above the central axis of the station, which is in line with the Peck settlement trough theory. 2021 Vol. 58 (6): 121-128 [Abstract] ( 704 ) [HTML 1KB] [ PDF 3042KB] ( 653 ) 129 Study on Influence of New Transfer Channel Construction on Deformation of Overlying Existing Metro Station in Sandy Pebble Stratum WANG Rui1 MIAO Longgang2,3 ZHANG Huijian2,3 NONG Xingzhong1 GUO Hongbo1 Based on the transfer channel project of Chengdu Metro Line 8, which is closely passes under the exist? ing metro station, the influence of mined excavation of the transfer channel on the track settlement, influence range and cross-section deformation of the existing metro station is analyzed by combining on-site monitoring and numerical simulation methods. It is concluded that: the settlement of the right track of the existing metro station is greater than that of the left track after completion of the mined excavation, the maximum settlement obtained by the numerical simulation is 4.82 mm and the error between the numerical simulation result and the measured value is 1.8%;along with the excavation of the pilot tunnel, the longitudinal beam of the existing metro station bottom slab is in a state of tension at the lower edge and compression at the upper edge within the influence range, the distance from the influence boundary of the existing metro station affected by the mined excavation to the excavation boundary is about 16 m and the influence range of the existing metro station is 55.5 m; in the process of mined excavation, a "tor? sion" phenomenon would occur in the cross-section deformation of the existing metro station, while the final crosssection settlement of the existing metro station at the exit side is slightly greater than that at the entrance side, with uniformity of the overall settlement. 2021 Vol. 58 (6): 129-136 [Abstract] ( 577 ) [HTML 1KB] [ PDF 5167KB] ( 795 ) 137 Study on Reinforcement of Large Arch Foot of Mined and Overlapped Metro Transfer Stations HUANG Peng1,2 WEI Liangwen1,2 ZHANG Xuefu1,2 In view of the limited ground suitability of the arch-cover method for construction of a metro station with super-large section, taking the Min′an Avenue station of Chongqing rail ring line as the background, the finite element software MIDAS GTS is used to compare the non-reinforcement scheme, reinforcement scheme with spread reinforced concrete foundation, reinforcement scheme with reinforced concrete load transfer piles and anchorage scheme for the large arch foot structure of the station and to optimize the support parameters so as to expand the application scope of the arch-cover method. The results indicate that: (1) the reinforcement of the arch foot structure could improve the stress and deformation of the arch foot and the whole structure; (2) the anchorage scheme should be preferred after structural deformation, ground settlement, structural stress, engineering economic benefits and construction difficulty have been considered comprehensively; (3) reasonable support parameters of the anchoring scheme should be 6 m/0.50 m×0.75 m; and (4) based on the anchoring scheme, the combined action of steel arch frame, side wall bolts and arch foot structure reinforcement could guarantee the safety of station structure. 2021 Vol. 58 (6): 137-147 [Abstract] ( 623 ) [HTML 1KB] [ PDF 5193KB] ( 640 ) 148 Study on Ground Settlement Prediction in Shield Tunnel Construction Considering Soil Arching Effect MA Qianying YE Jiachao JIANG Xiaohui In view of great difference between the predicted final ground settlement and the measured ground set? tlement during shield tunnelling, the conditions of soil arching effect in the process of shield tunnelling and its influence on ground settlement are considered on the basis of the Terzaghi theory. The back analysis is carried out to obtain the relationships between the tangent of ground influence angle tanβ, tunnel convergence area and tunnel buried depth, then the effects of cohesion, internal friction angle and tunnel buried depth on ground settlement are discussed, and the simplified formula of stochastic medium theory is modified accordingly. The comparison with monitored data from the actual project shows that the modified calculation method is more accurate for predicting ground settlement during shield tunnelling, the settlement caused by uneven soil stress decreases along with the increase of the tunnel buried depth and finally tends to be stable. The buried depth of the tunnel has the greatest influence on ground settlement in the construction phase, followed by internal friction angle and cohesion. 2021 Vol. 58 (6): 148-154 [Abstract] ( 560 ) [HTML 1KB] [ PDF 2104KB] ( 587 ) 155 Analysis of Influence of Arc Cutterhead on Ground Settlement during EPB Shield Construction WANG Yingxue1 LUO Yang1 ZHANG Ziwei1 WANG Guoyi2 SONG Xiangshuai1 During the shield tunnel construction, the form of cutterhead may have a certain impact on constructioninduced ground settlement. In view of this, the stress characteristics of balanced in-situ soil pressure in front of the arc and rectangular shield cutterheads are analyzed, the calculation formula of the balance pressure in the arc edge area and the selection method of the soil chamber pressure of the arc cutterhead are deduced, and the definition of the influence coefficient of the arc cutterhead is provided as well. FLAC3D numerical simulation software is used to analyze the ground settlement difference induced by excavation of arc and rectangular shield cutterheads, and the effects of soil pressure and soil unit weight in excavation chamber on ground surface settlement and tunnel face displacement. The results show that the ratio of ground settlement induced by arc and rectangular cutterheads obtained by numerical calculation is basically consistent with the influence coefficient of arc cutterhead obtained by theoretical analysis, which means that it is feasible to use this influence coefficient to evaluate the ground settlement differ? ence induced by rectangular and arc cutterheads. 2021 Vol. 58 (6): 155-162 [Abstract] ( 628 ) [HTML 1KB] [ PDF 2768KB] ( 640 ) 163 Study on Engineering Influence of Defects in Pea Gravel Backfilling and Grouting Layer ZHANG Jinliang1 HUANG Qiuxiang2 WANG Xueying1 HU Chao2 ZHANG Shaoxuan2 The pea gravel backfilling and grouting layer is an important part of the shield TBM tunnel lining system, and it is of great theoretical and practical significance in studying the impact of different defects in the pea gravel backfilling and grouting layer on construction works. In this paper, common defect types and its distribution law in the pea gravel backfilling and grouting layer are summarized on the basis of a diversion tunnel constructed by the double shield TBM. Then, the effects of different defect types on segment stress and displacement under different engineering conditions are systematically simulated and analyzed. The results show that common defect types mainly include cavity, non-dense grouting, plain cement and high rock powder content in cemented grouts; among others,cavity has the greatest impact, and the fully filling should be performed as much as possible; the vertical displacement of segments is sensitive to construction defects, the difference between horizontal and vertical displacements of segments might decrease under the action of internal water pressure in the pressurized tunnel; under the condition of Class Ⅱ surrounding rock, the influence of various defects is small, while that of other defects might be ignored ex? cept that cavity should be avoided as far as possible; in the Class Ⅳ surrounding rock the displacement and stress of segments are governed by the geological conditions, which would amplify the effect of defects, so that countermeasures should be taken accordingly; interaction of the internal water pressure and geological conditions would further amplify the influence of construction defects, the displacement of segments in Class Ⅳ surrounding rock is about 2~ 3 times of that in the Class Ⅱ surrounding rock, with especially prominent influence effect of cavity defect. 2021 Vol. 58 (6): 163-172 [Abstract] ( 703 ) [HTML 1KB] [ PDF 6226KB] ( 744 ) 173 Study on Thermal Stress Field and Cracking Control of Cast-in-situ Mass Concrete in a Box Tunnel FU Yifan1,2 WANG Linfeng1,2 CHENG Ping1,2 TANG Ning1,2 ZHOU Nan1,2 Cracking in mass concrete has always been an urgent research topic in the engineering field. So, in this paper, taking the cast-in-situ mass concrete of a multi-span multi-arch box tunnel in the Mountain Restoration Project in Xuzhou City, Jiangsu Province as the research background, temperature monitoring points are installed and the temperature at each monitoring point is measured during the pouring process of mass concrete, and then the secondary development function of ABAQUS finite element software is adopted to establish a finite element model of the single span tunnel, so as to simulate the thermal stress field of the mass concrete. Meanwhile, taking into consideration of the variations of concrete molding temperature, curing temperature, formwork removal time, pouring layer and so on, it analyzes the peak temperature at the center point, the maximum temperature difference between the core and surface as well as the surface tensile stress of the mass concrete in the tunnel. Finally, the variation law is concluded for thermal stress field of cast-in-situ mass concrete in the tunnel. The results show that: the variation law of the simulated temperature is basically consistent with the one measured on the site; when the concrete molding temperature and curing temperature increase by 20 ℃ , the peak temperature at the central point increases by 8.47 ℃ and 10.48 ℃, respectively, the maximum temperature difference between the core and surface increases by 6.35 ℃ or decreases by 6.79 ℃, respectively, and the tensile stress on the surface increases by 0.61 MPa or decreases by 0.52 MPa, respectively; Formwork removal and curing should be carried out about 3 days after pouring (when the concrete began to cool down) to minimize the peak temperature at the central point, the maximum temperature difference on inner surface and the tensile stress on the surface; the appropriate number of pouring layers is also conducive to the cracking control of the mass concrete. The on-site cracking control measures formulated according to the simulation results could effectively control the cracks of concrete structure and achieve good practical results. 2021 Vol. 58 (6): 173-181 [Abstract] ( 626 ) [HTML 1KB] [ PDF 4124KB] ( 649 ) 182 Informatized Control System for Lining Construction of Jishou Tunnel on Zhangjiajie-Jishou-Huaihua Railway ZHANG Minqing1 XIN Weike1 JIA Dapeng1 HAN Jingyu2 WANG Baiquan2 MA Weibin3 In order to eliminate the hidden quality dangers in railway tunnel lining, improve the lining quality, strengthen the control for the whole pouring process of the lining concrete and ensure the reliable quality and controllable safety of the tunnel lining, a set of informatized tunnel lining construction control system is introduced in this paper in combination Jishou tunnel of Zhangjiajie-Jishou-Huaihua railway, which integrates trolley positioning control, pouring and vibration control and construction information monitoring. Practical application in Jishou tunnel indicates that the system can realize the visualization, digitalization, information and intelligence for the whole pouring process of the lining concrete, achieve the centralized, efficient and convenient management goal, and is of great significance in improving the tunnel lining quality and construction efficiency and reducing the labor intensity of operators. 2021 Vol. 58 (6): 182-187 [Abstract] ( 605 ) [HTML 1KB] [ PDF 2657KB] ( 691 ) 188 Study on Key Intelligent Construction Technologies of Super-long and Deepburied Hydraulic Tunnels under Complex Geological Conditions HAO Junsuo In order to solve construction problems of a hydraulic tunnel under various complex geological condi? tions, taking the Shizishan tunnel of Water Diversion Project in Central Yunnan as background, this paper deeply analyzes main engineering geological problems and construction organization difficulties during the construction process by means of on-site investigation and monitoring, proposes the key intelligent construction technologies, and the following conclusions are obtained: (1) as for the super-long, high-risky tunnel constructed by the drilling and blasting method with multi working faces, the safe, rapid and efficient construction can be achieved through mechanization, automation and informatization from the aspects of method selection, machine matching, geological prediction, disaster monitoring, harmful gas monitoring and construction ventilation; (2) through accurate prediction of high-risk sources, targeted technical measures, intelligent monitoring means and informatized early warning mechanism can be taken to achieve the purpose of informatized pre-control of construction risks; (3) according to characteristics of complex geological conditions, high construction risk and high construction organization requirements of Shizishan Tunnel, the software platform of intelligent site management system should be used to realize multi-level,all-round, multi-dimensional and comprehensive intelligent management. 2021 Vol. 58 (6): 188-196 [Abstract] ( 523 ) [HTML 1KB] [ PDF 3779KB] ( 1613 ) 197 Construction Technology of Xiamen Haicang Subsea Tunnel Crossing Weathered Trough DONG Jiansong The weathered trough in seabed is a bad geological body with broken rock and poor self-stability. The left tube of the sea-crossing section of Xiamen second west passage (Haicang tunnel) passes through the longest weathered trough in China, with a total length of 160 m. The construction of subsea tunnel passing through weathered trough is difficult and risky. Once water inrush occurs, it will lead to disastrous consequences. In view of this,key construction technologies for tunnel passing the weathered trough are studied in detail based on engineering background of Haicang Tunnel. Specific schemes and methods, such as comprehensive advance geological prediction system, advance support, advance grouting for water blockage, grouting effect test and construction procedures of CD excavation method, are summarized as well; meanwhile, the tunnel displacement and deformation are densely monitored, measured and analyzed in the process of construction, ensuring the safe construction in weathered trough section. 2021 Vol. 58 (6): 197-203 [Abstract] ( 684 ) [HTML 1KB] [ PDF 2709KB] ( 755 ) 204 Study on Key Construction Technology of Advanced Small-pipe Curtain Support in Strongly and Moderately Weathered Mudstone Stratum LIU Jun′an LI Qi YOU Qianfeng ZHENG Jiajun CHEN Biao SONG Ruifeng LV Yang Compared with other advanced pre-support technologies, the pipe curtain support has high stability and good safety, and is widely used in soft soil layers. In this paper, in view of the complex surrounding environment of urban tunnels, the comparative analysis is performed for small-pipe curtain construction methods in strongly and moderately weathered mudstone stratum, the horizontal spiral guided drilling, reaming and pipe jacking method is proposed accordingly and relevant key technologies are studied as well. Then, the telescopic drill bit is studied and applied, and the construction measures for pipe curtain jacking accuracy control, trajectory control and jacking resistance reduction are put forward on the premise that the construction method is feasible. According to the design of the engineering support system, the alternative measures of arch foot-locking anchor pipes are proposed to ensure construction quality and safety. 2021 Vol. 58 (6): 204-209 [Abstract] ( 532 ) [HTML 1KB] [ PDF 2986KB] ( 764 ) 210 Research on Machinery Matching Design and Process Standardization Control in Tunnelling by Drilling and Blasting Method LI Wulun JIANG Zhengquan In order to solve the problems of low mechanization level, high labor intensity and slow construction progress in tunnelling by conventional drilling and blasting method, taking Feieshan tunnel on Yibin-Yiliang expressway as the engineering background, the detailed analysis is carried out from the aspects of construction organization scheme, mechanized equipment operation matching method, construction process standardization management, etc., and the machinery matching technology and process standardization control scheme are put forward,which are suitable for tunnelling by drilling and blasting method. The actual construction effects show that, compared with the conventional drilling and blasting method, using the machinery matching technology it can greatly improve the construction progress, reduce the production cost and lower the construction risk; and by implementing process standardization control it can significantly shorten the time required for each process. In the construction of Grade Ⅳ and Grade Ⅴ surrounding rock sections of Feieshan tunnel, by means of machinery matching design and process standardization control it can save 23.85 h and 27.5 h per cycle respectively compared with the traditional construction technology, achieving good social and economic benefits, and realizing the rapid and safe construction of Feieshan tunnel. 2021 Vol. 58 (6): 210-217 [Abstract] ( 703 ) [HTML 1KB] [ PDF 1604KB] ( 1213 ) 218 Study on Pre-reinforcement Schemes for a Shield Tunnel Passing under the Pile Foundation of an Urban Viaduct LIU Xialin ZHANG Jun CHEN Biguang LIU Shangge SHU Heng In this paper, the pre-reinforcement schemes for the pile foundations of an urban viaduct before shield construction are systematically analyzed on the basis of a shield-driven running tunnel passing under the existing urban viaduct, and four reinforcement schemes are put forward: namely the pre-reinforcement scheme with sleeve valve grouting pipes, the pre-reinforcement scheme with isolation piles, the pre-reinforcement scheme with sleeve valve grouting pipes + isolation piles, and the pre-reinforcement scheme with sleeve valve grouting pipes + isolation piles + additional pile foundations. Then, the design idea of each pre-reinforcement scheme is introduced in detail and the refined three-dimensional numerical simulation calculation is performed for four pre-reinforcement schemes. The results show that the pre-reinforcement scheme with sleeve valve grouting pipes alone and that with isolation piles alone have limited effect; the pre-reinforcement scheme with sleeve valve grouting pipes and isolation piles can desirably control the horizontal displacement, vertical settlement and differential settlement of piers and abutments, with good reinforcement effect; the pre-reinforcement scheme with additional pile foundations has limited contribution to settlement control, and so with a low cost performance. 2021 Vol. 58 (6): 218-224 [Abstract] ( 590 ) [HTML 1KB] [ PDF 2318KB] ( 811 ) 225 Study on Influence Law of Blasting Vibration and Vibration Reduction Technology in Urban Tunnelling YANG Zhao On the basis of the Donghai tunnel in Quanzhou, the paper, starting from the structural safety of sur? rounding surface buildings and the psychological endurance of people to blasting, explores the influence law of construction blasting on surface buildings through numerical simulation calculation and on-site monitoring. The influence of construction blasting on the psychological tolerance of nearby people is explored by means of designing the questionnaire on the psychological tolerance of people to blasting vibration, and carrying out statistical analysis of the results of 309 questionnaires by using t-distribution curve. On the basis of the maximum blasting vibration velocity, the blasting vibration reduction control technology for different sur-rounding rocks is put forward through theoretical derivation and regression fitting. The research results show that, considering the two major influence factors, namely, the safety of surface building structure and the psychological tolerance of people to blasting, the blast? ing vibration velocity in urban tunnel construction should be less than 1.11 cm/s; from the point of view of people′s psychological tolerance to blasting, the minimum safety distances for blasting vibration in surrounding rocks with various grades should be 35.9 m (Grade Ⅴ), 35.1 m (Grade Ⅳ) and 45.6 m (Grade Ⅲ) respectively, when the explosive charge is in the range of 24.63~ 34.5 kg. 2021 Vol. 58 (6): 225-232 [Abstract] ( 527 ) [HTML 1KB] [ PDF 3047KB] ( 1180 ) 233 Comprehensive Treatment Scheme and Design Suggestions on Inverted Arch Defects in Water-rich Soft Rock Tunnels WU Mingfang CHUN Junwei The problem of highway tunnel defects has become an unavoidable factor that affects traffic safety. Tak? ing a water-rich soft rock expressway tunnel as the research object, and in combination with the tunnel hydrogeological conditions and the tunnel defect conditions, the causes of inverted arch defects are analyzed, the simulation analysis is carried out by a numerical calculation software, and then the complete treatment measures are proposed accordingly. Actual results show that the treatment measures are reasonable and effective. On this basis, a set of treatment schemes is summarized for defects in the tunnel inverted arch in weak surrounding rock with rich groundwater,so as to provide references for treating the defects of the inverted arch under similar conditions and to put forward some suggestions for tunnel design under similar conditions. 2021 Vol. 58 (6): 233-243 [Abstract] ( 633 ) [HTML 1KB] [ PDF 5765KB] ( 1191 ) 244 Influence of High-performance Synchronous Grouting Material on Shield Construction Parameters in Water-rich Sand Layer GAO Pengpeng1 XU Fang1 SONG Putao2 WANG Ningning3 ZHANG Wei4 A high-performance shield grouting material suitable for water-rich sand layer is prepared on the basis of the engineering background of Nantong Rail Transit Line 1 in water-rich sand layer. Then, comparative study is performed for the grouting performances of the prepared high-performance grouting material and existing grout used on the site as well as their influence law on shield construction parameters. The results show that: compared with the lot section used with existing grouts, the shield machine in the test section used with high-performance synchronous grouting material has the following properties: the soil chamber pressure increases from 0.22 MPa to 0.25 MPa, the average thrust increases from 12 000 kN to 15 000 kN, the cutter head torque increases from 1 150 kN·m to 1 450kN·m, the grouting amount decreases from 5.7 m3 to 5.2 m3 and the surface settlement is only 8.15 mm, so that the material cost is significantly reduced and the surface settlement could be effectively controlled. Furthermore, the relationship among key construction parameters of the shield is analyzed to find that the continuous reduction of grouting volume might have a certain impact on the soil chamber pressure, thrust and torque of the shield machine; when the shield machine drives at a constant speed, the variation laws of the curves of the soil chamber pressure, shield thrust and torque are consistent. 2021 Vol. 58 (6): 244-250 [Abstract] ( 644 ) [HTML 1KB] [ PDF 2961KB] ( 695 ) 251 Study on Preparation of Synchronous Grouting Material from Excavated Red Sandstone in Shield Tunnelling GUO Guibin1 JIN Shihe2 LIU Qi2 SUN Hongbin2 The shield-driven tunnels of Lanzhou Metro pass through a large area of red sandstone stratum with rich water, low cementation, good grading and the mud content of about 5%. Direct mucking after shield excavation might not only waste resources, but also cause relevant environmental problems. So, in this paper, a feasibility study is carried out for replacing river sands of synchronous grouting materials with red sandstone from shield tunnelling.The results show that the synchronous grouting mortar prepared with red sandstone can meet all technical indexes,with saving cost by about 40%, achieving better fluidity and reducing plugging rate by about 70%. The mud content of grout can be controlled by adjusting the addition amount of bentonite. Moreover, the permeable stone can also be made of red sandstone and used for municipal roads and other projects. It might not only solve the tight supply of raw materials in engineering construction, but also alleviate environmental damage caused by sand and stone mining in mountains and rivers. 2021 Vol. 58 (6): 251-256 [Abstract] ( 562 ) [HTML 1KB] [ PDF 1231KB] ( 976 )

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