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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2022 Vol.59 Issue.3 Published 2022-06-25 1 A Critical Reflection on Innovation Themes of Conventional Tunnelling WANG Jianyu The complexity and uncertainty of the geological body, the concealment of the structure, and the distur? bance in natural environment caused by tunnelling make the tunnel project built by conventional tunnelling very special compared to common types of construction projects. So, it is still necessary to discuss the safety risk, quality and environmental friendliness of the conventional tunnelling. In respect of the three themes mentioned above, this paper aims to address the following problems: (1) Data interpretation and information feedback in in-situ monitoring process is not yet successful. (2) The integration of the support system is the key issue concerning the tunnelling quality. (3) An innovative concept of tunnel waterproofing needs to be put forth for environmental friendliness. 2022 Vol. 59 (3): 1-9 [Abstract] ( 621 ) [HTML 1KB] [ PDF 3948KB] ( 1008 ) 10 A Discussion on Several Core Issues of Synchronous Grouting in Shield Tunnelling WEI Xinjiang1,2 ZHANG Biao1 LU Liangliang2 LIU Yingjing3 ZHU Hanhua2 WANG Hailin1 In the process of shield tunnelling, synchronous grouting for shield tail gap is a crucial process to alleviate problems caused by the tunnelling, such as ground loss, tunnel deformation and ground subsidence. This paper offers a brief overview of the development of synchronous grouting in shield tunnelling and a brief discussion on several core issues of such grouting method, including the selection of grout materials, the control of construction parameters, the mechanism of grout diffusion, the action of the grout on the shield segments and rock-soil masses, and the evaluation of the grouting effect. For different core issues, the focused analytical method is different (indoor model test, field measurement, theoretical analysis and numerical simulation). Based on the status-quo of relevant studies,the directions for future research are proposed from different perspectives with a view to providing useful guidance for relevant researchers and engineers. 2022 Vol. 59 (3): 10-22 [Abstract] ( 507 ) [HTML 1KB] [ PDF 3701KB] ( 1391 ) 23 Research in the Impact of Shield Tunnel Crossing on Existing Pipelines and Future Research Trends MA Jian When urban shield tunnels cross over existing pipelines, such crossing will have an impact on the pipe? lines. This paper reviews the status quo of the research in the impact of shield tunnel crossing on existing pipelines in terms of the following four aspects: theoretical equation, simulation calculation, model test and on-site measurement. Firstly, in theoretical study, three types of pipeline models were mainly compared and analyzed on the basis of soil deformation, and the method for selecting key parameters was discussed in detail. Secondly, although simulation and model test had direct advantages in the study on parameters related to the interaction between pipelines and ground, and what the study focused on had been changed from univariable coupling to multivariable coupling, the rationality of study results still relied to a large extent on the selection of constitutive model and test equipment. Lastly, as for pipeline deformation measurement, the initial analysis was conducted for the similarities and differences of two tunnel crossing methods. Besides, this paper also introduces the "sheltering effect" of the adjacent existing structures and the impact of pipeline joints on the predicted results, and summarizes control indicators and preventive measures from the aspect of flexible pipes and rigid pipes. Among the passive protection measures, grouting for reinforcement is the most widely used one. 2022 Vol. 59 (3): 23-30 [Abstract] ( 546 ) [HTML 1KB] [ PDF 2720KB] ( 1122 ) 31 Study on New Tunnel Support System Based on Norwegian Method Q System WANG Zhilong1 WANG Weihao2 LIU Dagang1 YAN Zhiwei1 TIAN Hongtao1 In terms of Class Ⅳ and Class Ⅴ soft surrounding rock, the following problems exist in the tunnel support system of China: poor effect of restricting early deformation of surrounding rock, low construction efficiency, and low economical efficiency. To ensure the tunnel supports can timely provide sufficient supporting force to effectively control the early deformation of surrounding rock and further improve the construction efficiency, this study, employs several study methods, such as data research, numerical simulation and theoretical calculation, etc., puts forward a new tunnel support system based on the Norwegian method Q system, and conducts the feasibility study in terms of economical efficiency and construction efficiency. The study results show that this new tunnel support system is characterized by better economical efficiency and construction efficiency, and the existing construction conditions of China can meet the requirements for the promotion and application of this system. 2022 Vol. 59 (3): 31-39 [Abstract] ( 585 ) [HTML 1KB] [ PDF 2220KB] ( 1000 ) 40 A Discussion on the Control Standards for Smoke CO Concentration during Fires in High-altitude Railway Tunnels WANG Mingnian1,2 GUO Xiaohan1,2 NI Guangbin3 YU Li1,2 LI Chunhui1,2 Current consideration of smoke toxicity during a fire in the design of railway tunnel evacuation and rescue has been mainly focused on plain areas. However, with the increase in altitude, the oxygen concentration in the tunnel decreases, aggravating the toxic gases in the smoke of the fire, especially CO toxicity, and reducing the tolerance time of trapped personnel for identical CO concentration. Therefore, it calls for more discussions and investigations on the safety of the design according to the control standards for smoke CO concentration in fires in plain areas.With the help of the CFK formula, this paper, based on the two scenarios of casualty within 30 minutes, and loss of evacuation ability within 5 minutes, investigates the effect of altitude on the time of human tolerance of the same smoke CO concentration, as well as the limits of smoke CO concentration in tunnel fires at different altitudes. The results show that the increase in the altitude and in the smoke CO concentration both accelerates the changing rate of human COHb concentration during the rapid-growth phase. The time of human tolerance of the same smoke CO concentration gradually drops with the increase of altitude. This paper shows the prediction formula for the reduction factors of the time of human CO tolerance at different altitudes. With the value of human COHb concentration being less than 60% and 28.6% as the benchmark, this paper establishes the calculation formulas of human tolerance of critical smoke CO concentration for the two scenarios of casualty within 30 minutes and loss of evacuation ability within 5 minutes during fires at different altitudes, respectively. 2022 Vol. 59 (3): 40-45 [Abstract] ( 538 ) [HTML 1KB] [ PDF 1634KB] ( 812 ) 46 Study on Grouting and Sealing for Tunnels in the Fault Fracture Zone Based on Ecological Protection ZHANG Dewen SU Dingwu A fault fracture zone is one of the common adverse geological phenomena encountered in tunnel projects, which often results in water inflows, collapses and other disasters. So it is a key risk to be controlled during the construction of tunnels. Taking Wuzhishan Tunnel project as a study case, this paper conducted a research in the grouting and sealing technology for tunnels in the fault fracture zone based on ecological protection. The study results showed that (1) from the perspective of ecological protection, the calculation methods for limited drainage volume to recover the water table in a given period of time were put forward respectively for pre-grouting and post-grouting schemes.In terms of Wuzhishan Tunnel project, the limited drainage volumes to recover the water table in one year was 1.82m3/(d·m) and 0.96 m3/(d·m) respectively for pre-grouting and post-grouting schemes; (2) combined with the limited drainage volume of groundwater and the drainage volume after grounting for surrounding rock, a method was proposed to calculate the grouting ring thickness of surrounding rock. In the pre-grouting and post-grouting schemes of Wuzhishan Tunnel, the grouting ring thickness corresponding to the recovery of water table in one year was 2.07 m and 4.5 m, respectively. 2022 Vol. 59 (3): 46-52 [Abstract] ( 593 ) [HTML 1KB] [ PDF 784KB] ( 797 ) 53 Study on the Adaptability and Selection of Multi-mode Tunnelling Equipment for Subway Tunnels CHEN Fan1 HE Chuan1 HUANG Zhonghui2 MENG Qingjun2 LIU Chuankun1 WANG Shimin1 Urban subway tunnel construction at home and abroad has shown different development trends, such as long distance, diversified geological conditions and complex construction environment, posing great challenges to the adaptability of existing mechanized construction methods. Multi-mode shield/TBM tunnelling equipment has good adaptability in complex environments, making it useful to solve the challenges in selecting the tunnellling equipment for composite stratum by reducing the construction risks while improving the tunnelling efficiency. This paper is a discussion of the adaptation of different types of multi-modal tunnelling equipment to different strata and working characteristics. Also, this paper proposes the principles and methods for the selection of multi-mode tunnelling equipment through statistical analysis of key stratigraphic parameters based on typical engineering cases at home and abroad where multi-mode tunnelling equipment is used. Furthermore, paying comprehensive consideration to the geological conditions, duration, cost and environmental impact, this paper constructs a comprehensive evaluation model of shield and TBM mode adaptability respectively, and determines the lower limit length of mode conversion with consideration to the duration and cost, before making modification of the interval mode. Finally, using the running tunnel of Shenzhen Metro Line 14 as an example, the research results verify the reasonableness of the multimode tunnelling equipment selection method. The research results can provide references for the promotion and application of multi-mode tunnelling equipment in China′s tunnel engineering and adaptability evaluation. 2022 Vol. 59 (3): 53-62 [Abstract] ( 601 ) [HTML 1KB] [ PDF 3713KB] ( 825 ) 63 Prediction of Tunnel Face Stability Based on Support Vector Machine and Ensemble Learning LI Bin1 LAN Yuansheng1 ZHANG Congxu2 The stability of a tunnel face is influenced by a variety of factors, and it is necessary to assess the stability of the tunnel face before tunnel excavation, so as to develop appropriate measures and ensure the safety of the tunnelling process. To improve the efficiency of prediction, this paper proposes a method for the fast prediction of tunnel face stability based on ensemble learning and support vector machine (SVM). First, the most typical training samples are selected based on the principle of orthogonal experimental design, and then the samples are calibrated through three-dimensional numerical calculations. Second, based on the SVM algorithm, different kernel functions are used to fit the prediction models of tunnel face stability and verify their prediction accuracy through the leave-one-out method. Finally, according to the ensemble learning mechanism, the prediction models are synthesized by the voting method to realize the integrated prediction of tunnel face stability. The results show that the ensemble learning mechanism can minimize the generalization error of individual prediction models and improve the reliability of the prediction results of tunnel face stability. 2022 Vol. 59 (3): 63-71 [Abstract] ( 540 ) [HTML 1KB] [ PDF 1876KB] ( 761 ) 72 Application of Virtual Reality Technology to Shield Tunnelling in Karst Areas HUANG Bin1 WANG Wei2 ZHANG Longguan1,3 TUO Hongtao1 WANG Liangdong1 This study utilizes 3DMAX to establish a model base of tunnels built by the shield tunnelling method, and creates a panoramic display of the construction site by Unity3D engine technology and virtual reality hardwares on the basis of geological investigation data and advanced geological prediction results. The actual application of this technology to shield tunnelling in karst areas demonstrates that: in advanced geological prediction for shield tunnelling, virtual reality technology can directly show the spatial form of tunnel strata to non-geologist users,reduce the need for communication among the personnel, dispaly the geological information and advanced prediction results of the tunnel area in a clear, three-dimensional and dynamic way, and provide a large amount of geological information for shield tunnelling in time, thus increasing the safety of tunnel construction. 2022 Vol. 59 (3): 72-77 [Abstract] ( 507 ) [HTML 1KB] [ PDF 2812KB] ( 733 ) 78 Analysis on the Reliability of Tunnel System Based on Multiple Response Surface Methodology and Monte Carlo Method LIU Zhiliang1 LIN Houlai1 LI Liang1 LI Dongxian1 GAO Yuan2 XU Liang1 HU Jun3 As soft rock tunnels have the disadvantages of high construction risk and high complexity of support struc? ture and construction process, it is difficult to directly calculate the limit state function of tunnel structure. So, this paper discusses an analysis method for the reliability of the tunnel system using finite element numerical simulation in combination with multiple response surface methodology and Monte Carlo method. Its suitability was verified in the case of one soft rock subway tunnel in Qingdao. The results showed that the surrounding rock characterized by "soft upper ground and hard lower ground" had a very large difference in lithology between the upper and lower parts, and the system failure probability of tunnel structure was mainly affected by the upper soft rock and rarely affected by the lower hard one; a change in the elastic modulus (E1) and internal friction angle (φ1) of pebble bed had the most significant impact on the system failure probability, and the tunnel system failure probability increased with the increasing of parameter variability of surrounding rock; due to the relevance between failure modes, it is not adequate only to take into consideration the failure of out-of-limit tunnel deformation or insufficient support bearing capacity, while the system reliability study based on multiple failure modes using deformation and bearing capacity as the controlling conditions was more suitable for the soft rock tunnel structure. 2022 Vol. 59 (3): 78-87 [Abstract] ( 547 ) [HTML 1KB] [ PDF 4485KB] ( 681 ) 88 Response Analysis on Structural Mechanics of Tunnel Lining Taking into Consideration the Spatial Variability of Parameters ZHANG Huan Based on the spatial variability of parameters of the support-surrounding rock system, this paper puts for? ward the random finite element analysis method for non-linear foundation beams under the basic framework of random field theory. In the analysis, the Karhunen-Loève series expansion method was utilized for random field discretion, the spatial variability of the interaction between the surrounding rock load and the support-surrounding rock system was simulated, and the multiple random variable model was used to simulate the spatial variability of lining parameters. On such basis, the non-linear spring and the modified Timoshenko foundation beam unit were utilized to build the non-linear foundation beam unit, and the corresponding calculation program was written. This program was used to analyze the mechanical response of supports and in the process, 4 types of typical mechanical response rules were found: (1) the degree of impact of the same variation source on the mechanical response of supports was selective; (2) the level of sensitivity of the same mechanical response on the variation source was various; (3) the impact of the grade of surrounding rock on the mechanical response rules was decisive; and (4) the spatial distribution patterns of mechanical response were uniform. 2022 Vol. 59 (3): 88-98 [Abstract] ( 477 ) [HTML 1KB] [ PDF 4933KB] ( 901 ) 99 Analysis of the Dynamic Response of Twin-tunnel Rail Sleepers and Lining under the Action of Trains MENG Xiancong1 ZHANG Xiedong1 WU Lin2 ZHU Haojie1 LI Zhifeng1 To study the dynamic response of closely-spaced subway twin tunnels under the action of train vibration, this paper establishes a discrete element model of twin tunnels based on particle flow code (PFC). The model simulates three scenarios during subway operation to analyze the impact of a single passing train (with 6 carriages) on the adjacent tunnel and its own tunnel, as well as the impact of two simultaneously passing trains on the twin tunnels.The results show that after the train enters the tunnel (1-3 carriages), there is a gradual increase with fluctuations in the vertical dynamic response of the tunnel , and then (4-6 carriages), the peak vertical dynamic response of the tunnel gradually stabilizes, and the vertical vibration amplitude of the lining of its own tunnel is, on average, 23% smaller than that of the adjacent tunnel. The dynamic response of the tunnel lining reaches its maximum value when the two trains are passing simultaneously with a maximum vibration displacement of 6.4 mm, which occurs near the middle of the twin tunnels. This indicates that closely-spaced twin tunnels should be monitored for lining vibrations near the middle area with a focus on preventing microcracking. 2022 Vol. 59 (3): 99-106 [Abstract] ( 522 ) [HTML 1KB] [ PDF 3797KB] ( 980 ) 107 Analysis of the Dynamic Effect of Traffic Load on Shallow Multi-tube Tunnel Structure YAO Zhixiong1,2,3 JI Lei1 LIU Yaoxing1 HUANG Min4 ZHANG Zhongxing4 CUI Ying1 Taking as a study case a shallow four-tube tunnel project passing under a highway in Fujian, this paper establishes a road surface-surrounding rock-tunnel vibration analysis model based on vehicle load dynamics theory to analyze the dynamic response of the shallow multi-tube tunnel structure under vehicle load action. The results show that the time history curve of vertical displacement presents an "inverted bimodal" shape with semi-intense oscillation, while the peak displacement generated by the vehicle load action of one carriageway is much larger than that of the other carriageway in the opposite direction, and the dynamic displacement effect on multi-tube tunnel is small. The dynamic stress is distributed in an asymmetric "clover" shape along the circumference of the tubes and concentrated in the shoulder area. The dynamic stress amplitude of the shoulder increases significantly when the dual carriageway is fully loaded compared with the other solutions, and such a long-term effect should not be neglected. This paper thus puts forward a reasonable mode for the load distribution of highway lanes. The elasticity modulus of each rock-soil mass has a large impact on the transmission of dynamic stress, and the larger the surface elastic modulus is, the faster the attenuation of the dynamic stress will be. However, when it reaches the tunnel structure, it will start reflecting and rising. Therefore, increasing the stiffness of the road surface or the range of the tunnel reinforcement ring can reduce the impact of dynamic stress on the tunnel. The reasonable control of traffic density can significantly reduce the dynamic stress of the tunnel shoulder, while cyclic vehicle load actions will increase the peak of the tunnel dynamic stress by 60.98%~81.3%. By analyzing the degree of impact, it is found that the dynamic stress in the tunnel surrounding rock when the four lanes are in a full traffic jam is 12.68 times higher than that when there is only a half-carriageway traffic jam. 2022 Vol. 59 (3): 107-117 [Abstract] ( 450 ) [HTML 1KB] [ PDF 5725KB] ( 719 ) 118 Analysis of Deformation Impact of the Adjacent Over-crossing Parallel Tunnel Excavated by the Shallow Mining Method on the Existing Shield Tunnels XU Youjun1,2,3 QIN Haobin1 LI Wenbo4 ZHANG Xu1,2,3 ZHANG Chao1,2,3 LI Zesheng4 Given that the tunnel excavated by the shallow mining method adjacently crossed over the existing Metro Line No.2 in a parallel way in Hohhot, the scheme comparison was carried out for different excavation methods and counter-pressure measures by means of finite element numerical simulation and on-site monitoring, and the study was conducted on the floating deformation pattern of shield tunnel structure caused by over-crossing construction.The results showed that the use of sandbags for counterpressure during construction could effectively control the deformation of shield tunnels, and through comparison, it has been found that the vertical displacement control rate of the second sandbag counterpressure was significantly lower than that of the first sandbag counterpressure. So, sandbag counterpressure for tunnels should be conducted during on-site construction as early as possible to avoid a smaller vertical displacement control rate caused by delayed counterpressure, which would further lead to a failure to realize a good effect of counterpressure. It has also been found that the curve of tunnel deformation of Metro Line No. 2 caused by the over-crossing works was of a "semi-parabolic" shape, and the phenomenon of left-right conversion occurred with the excavation and unloading of the new tunnel. Besides, unhomogeneous deformation occurred in shield tunnel segments due to various factors, such as soil unloading, shallow depth of overburden, etc. and the overall deformation of the existing shield tunnel segments was of a "vertical duck egg" shape. The finalized scheme of the Works was CD method + two-sided counterpressure based on economical factor, efficiency and other factors.After the optimization scheme was adopted in the Works, the maximum floating deformation of the shield tunnel roadbed was finally controlled at 2.51 mm, which complied with the specified control value, i.e. 4.0 mm. 2022 Vol. 59 (3): 118-127 [Abstract] ( 493 ) [HTML 1KB] [ PDF 5790KB] ( 747 ) 128 A Study on the Foundation Resistance Coefficient in Longitudinal Uplift Analysis Model for Shield Tunnels WU Lin1,2 WANG Wei2 FENG Kun2 TAO Weiming1 MENG Qinghui2 ZHEN Wenzhan1 During the process of shield tunnelling, there is a common problem with the local or overall uplift of the segments near the tail of the shield. To analyze the problem of segment uplift of shield tunnels during tunnelling,this paper addresses the foundation resistance coefficient in the longitudinal uplift analysis model for shield tunnels.Firstly, based on the characteristics of the overall uplift of the tunnel in the cross-section, this paper uses the elastic mechanics method to derive the theoretical solution of the foundation resistance coefficient by taking into account the influence of the grouting layer; secondly, based on an actual project, this paper compares and analyzes the differences in the foundation resistance coefficient when using this theoretical solution and the conventional calculation method, as well as their effects on the calculation results of the longitudinal uplift of the shield tunnel. The results show that the conventional calculation method significantly underestimates the foundation resistance coefficient, where the calculated values of the maximum uplift, the bending moment and the influence range of the tunnel are too large, while the calculated value of the shear force is too small. 2022 Vol. 59 (3): 128-135 [Abstract] ( 498 ) [HTML 1KB] [ PDF 1718KB] ( 694 ) 136 Analysis of the Shock Absorption of Tunnel-Soil-Surface Building Interaction System XIE Jun1,2,3 DUAN Long2 LIANG Jinxiao2 LI Yantao1 SONG Jinhui1 A 3D finite element calculation model was established to analyze the shock absorption effect of shock ab? sorption measures taken for the tunnel-soil-surface building interaction system, and the time-history analysis method was adopted to analyze the dynamic response of this model. Based on the analysis of the acceleration, displacement and stress responses of tunnels and surface buildings, the impact of the thickness of shock absorption layer on the shock absorption effect of this system was studied when the tunnel shock absorption layer (or foundation shock absorption layer) was independently set. In addition, a novel scheme of combined shock absorption was put forward,and the primary and secondary relationship of different factors in terms of the impact on shock absorption effects was studied through orthogonal test. Finally, the shock absorption effects of these combined shock absorption measures were analyzed under different seismic waves. The results showed that (1) the shock absorption layer of a tunnel could significantly reduce the stress and acceleration of the tunnel, but if the elastic modulus of the shock absorption layer was too small, the tunnel displacement response would be enlarged; (2) when the depth of the foundation shock absorption layer was 0 m, the best shock absorption effect would be obtained and the relative displacements of surface buildings could be significantly decreased; and (3) the combined shock absorption measures taken under different seismic waves could realize a good shock absorption effect, and meanwhile, such shock absorption effect was superior to that of the single shock absorption layer. 2022 Vol. 59 (3): 136-145 [Abstract] ( 531 ) [HTML 1KB] [ PDF 4344KB] ( 692 ) 146 Seismic Response Simulation of Submerged Floating Tunnel with Tension Legs: A Case Study on the Qiongzhou Strait Crossing Tunnel Project LI Hao1 CHENG Xiaohui1 YU Hanliang1 FU Dan1,2 Submerged floating tunnels (SFTs) are less affected by the depth of water, undersea topography and geo? logical conditions, and are less costly than deep-buried tunnels and immersed tube tunnels. However, there are still major technical problems to be overcome for their better application. This paper uses the Qiongzhou Strait crossing unnel project as a study case to conduct an analysis of the static load and dynamic response of SFT structures, taking into account the joint action of earthquake-induced hydrodynamic load, dead weight, buoyancy and other loads.Furthermore, this paper also integrates the use of the Rayleigh damping equation and Morison equation to carry out a tentative study on the calculation of additional damping of SFTs. The results show that, in the static analysis, the maximum cross-sectional bending normal stress occurs at the bottom plate where the two ends are embedded with the rock formation, while in the dynamic time-course analysis, the displacement in the X-direction (axial) is larger than that in both the Y- and Z-directions under the influence of seismic waves; As SFTs with tension legs are most likely to have problems with the cables under the influence of seismic action, it is necessary to pay more attention to the dynamic performance of the cables in the mooring system to ensure the stability and safety of an SFT structure. 2022 Vol. 59 (3): 146-154 [Abstract] ( 440 ) [HTML 1KB] [ PDF 3358KB] ( 791 ) 155 Study on the Impact of Shield Tunnel Under-crossing at Ground Fissure Site on Existing Utility Tunnels MIAO Chenyang1 HUANG Qiangbing1,2 GOU Yuxuan1 TENG Hongquan3 JIA Shaochun4 There is a serious safety risk when the shield tunnel at the ground fissure site crosses under the existing utility tunnels. Based on the case of the shield tunnel of Xi′an Metro Line 5 that crosses under the utility tunnel under Kunming Road at f3 ground fissure site, the finite element numerical simulation and theoretical analysis method was adopted in this paper to analyze the impact of under-crossing shield tunnel at the ground fissure site on the existing upper utility tunnel and to reveal the pattern of changes in the displacement and stress of utility tunnel structure caused by such under-crossing. The results showed that when the shield tunnel crossed the utility tunnel from the footwall to the hanging wall at the ground fissure site, the deformation of utility tunnel was increased by 30.9% compared to that on the site without ground fissure; the utility tunnel structure had a stress reduction zone (i.e. zone of influence) around the ground fissure, with an influence area covering about 4 m from the hanging wall and about 16 m from the footwall, and the side wall stress of the utility tunnel outside the stress reduction zone more than doubled compared to that at the site without ground fissure, and the bottom stress was increased by about 40%; the impacts of ground fissure on the utility tunnel structure include enlarged deformation and superposition, a reduction in the stress around the ground fissure zone, and an increase in the stress outside the zone of influence. 2022 Vol. 59 (3): 155-165 [Abstract] ( 509 ) [HTML 1KB] [ PDF 5582KB] ( 861 ) 166 Analysis on Factors Influencing the Pneumatic Load during Train Operation in High-speed Railway Tunnels YAO Jie1,2 The pneumatic load generated by a train passing through tunnels at high speed is closely related to the fa? tigue life of the overall metal structure of the train, the windows, the windshields and the air conditioning and ventilation units, thus making it one of the important factor to consider in guaranteeing the safety of the train. This analysis uses a one-dimensional compressible non-constant nonequivalent entropy flow model and the generalized Riemann variable characteristic line method to investigate the effects of the train ′ s airtight performance, train length,blockage ratio and tunnel length on the pneumatic load of the train body during train operation (400 km/h) in a highspeed railroad tunnel. The results show that the better the airtight performance of the train is, and the longer the train formation and the larger the blockage ratio are, the greater the amplitude and the longer the action time of the pneumatic load will be. Also, with the increase of the tunnel length, the pneumatic load amplitude shows a trend of increasing before decreasing with an "unfavorable tunnel length", and the pneumatic load amplitude of the train body can be conservatively estimated by calculating the pressure amplitude of the train body ′s surface. 2022 Vol. 59 (3): 166-171 [Abstract] ( 564 ) [HTML 1KB] [ PDF 1919KB] ( 729 ) 172 Comparative Test and Analysis of the Deformation in Enclosure Structure of Internally-braced and Cantilevered Locked Steel-pipe Pile Foundation Pits LIANG Rongzhu1,2 WEI Shi1 WANG Xinxin3 SUN Lianwei3 WU Xiaojian3 Locked steel pipe (LSP) piles can form a row-pile enclosure structure by interconnecting the lock joints, and have been widely used in foundation pit projects in soft soil areas. To investigate the stress and deformation characteristics and differences between cantilevered and internally-braced LSP pile enclosure structures, this paper carries out similar model tests of the pit excavations of both cantilevered and internally-braced LSP pile enclosures respectively, and uses 3D printing technology to produce the piles with locked joints for the model tests. During the test, real-time monitoring and analysis were conducted for pile-top horizontal displacement, pile strain and soil surface settlement. The test results show that: (1) The LSP pile model made through 3D printing has the advantages of high precision and fast speed, implying that it can greatly reflect the joint characteristics of LSP piles; and (2) For the cantilevered enclosure structure with LSP piles, from the excavation of the foundation pit to the failure of the enclosure structure, the soil settlement distribution gradually shifts from a notch-type distribution to a triangle distribution, with the reverse-bending point of the pile moment appearing near the excavation surface and drops with the increase of the excavation depth. The ratio of the extreme value of the surface settlement to the extreme value of the horizontal displacement of the piles (δvm/δhm) is approximately 1, but when the enclosure structure loses its effectiveness, the position of the reverse-bending point almost has no change, while the ratio of the maximum settlement of the ground surface to the maximum lateral displacement of the piles (δvm/δhm) gradually decreases between the range of 0.5 and 0.75. For the internally-braced enclosure structure with LSP piles, under the same excavation depth, the soil settlement distribution is in a groove-type distribution, with the reverse-bending point of the pile moment remaining on the excavation surface the whole time, and the ratio of the maximum surface settlement to the maximum lateral displacement of the piles (δvm/δhm) gradually increases from 0.5 to 1. 2022 Vol. 59 (3): 172-182 [Abstract] ( 544 ) [HTML 1KB] [ PDF 5480KB] ( 676 ) 183 A Field Test Study on the Large Deformation Control for Tunnels Built in Seriously-weathered Carbonaceous Slate Strata with High Geostress CUI Guangyao1 WEI Hanghang1 WANG Mingsheng2 In view of the various problems caused by seriously weathered carbonaceous slate strata with high geo? stress, such as the development of joints and fractures, the fracture of the surrounding rock, and prominent large deformation hazards during the tunnelling process, this paper carries out a field test study on the advanced control measures for surrounding rock stress. The results show that conventional support measures cannot effectively solve the large deformation problem encountered by tunnels built in seriously-weathered carbonaceous slate with high geostress, and the use of advanced control measures for geostresses can effectively reduce the surrounding rock deformation of a tunnel while reducing the stress in the tunnel steel frame and surrounding rock. In contrast to the control section using conventional measures, the final values of horizontal convergence in the advanced borehole and pilot tunnel test sections are 152.93 mm and 149.22 mm, respectively, with a decrease of 27.95% and 29.70%; the final values of the crown settlement are 24 mm and 15 mm respectively, with a decrease of 61.29% and 75.81%; the maximum values of the steel frame stress are - 143 MPa and -157 MPa, respectively, with a decrease of 23.12% and 20.28%; and the maximum values of the surrounding rock stress are 0.379 MPa and 0.406 MPa, respectively, with a decrease of 77.44% and 75.84%. 2022 Vol. 59 (3): 183-189 [Abstract] ( 551 ) [HTML 1KB] [ PDF 3845KB] ( 901 ) 190 Study on the Adaptation of Different Rolling Velocities of Disc Cutters to Rocks with Joint Characteristics ZHOU Peng1 YAN Feng1 SUN Jian1 HE Enguang1,2 TIAN Junxing1 This paper is to demonstrate the impact of rolling velocity variation of the disc cutter on the efficiency of breaking rock with joint characteristics, and to verify the changing pattern of rock specific energy under the combined variation of the rolling velocity of the disc cutter and the joint characteristics of the rock. The ABAQUS finite element software is used to establish the rock-breaking model based on granite, simulate the rock-breaking process under rolling velocity variation, and analyze the magnitude of the cutter rolling force under different rolling velocities and joint characteristics, as well as the trend of specific energy change and breaking effect. The test results show that: when the spacing of the rock joints is of a fixed value, the greater the rolling velocity is, the greater the average rolling force the cutter will bear, and the greater the specific energy of rock-breaking it will have; At a constant rolling velocity, the rock-breaking ratio increases when the spacing of the joints increases from 120 mm to 200 mm; The variation of specific energy is stable when the spacing of the rock joints is 120 mm; Under a fixed spacing value of the rock joints, the dip angle of the joints becomes larger, and the rock-breaking ratio shows a trend of rising before dropping; When the spacing and dip angle of the rock joints are fixed, the rolling velocity and the average rolling force both increase, as well as the specific energy, while the rock-breaking efficiency decreases. The rolling velocity of the disc cutter has a significant impact on the breaking efficiency of rocks with joint development, while the characteristics of the joints also have a large impact on the breaking efficiency. 2022 Vol. 59 (3): 190-200 [Abstract] ( 497 ) [HTML 1KB] [ PDF 6107KB] ( 614 ) 201 Experimental Study on the Changing Pattern of Design Parameters of Controlled Drainage in Tunnels HUANG Shiguang1 YANG Yanna2 FAN Quanzhong2 HUANG Jingyu2 YU Lei2 On the basis of the groundwater seepage theory, this paper uses the analytical calculation method for existing external water pressure reduction coefficients and optimizes the calculation formula for the external water pressure reduction coefficients of tunnel lining under the condition of limited drianage. A large-scale seepage model test system for tunnels was utilized to simulate the limited drainage conditions in the optimized formula through a model test,and a research was conducted into the changing pattern of the reduction factors under comprehensive influence factors, such as tunnel drainage and grouting ring permeability coefficients, as well as into the impact of tunnel drainage and grouting ring permeability coefficients on the design parameters of tunnel drainage control, so as to compare and analyze the formula before and after optimization and to verify its correctness. The results show that: (1) the re? duction factor β decreases with the increase of tunnel drainage design parameter under the same grouting ring permeability coefficient but different drainage volumes; (2) the coefficient m of the tunnel drainage design parameter inreases with the increase of the grouting ring permeability coefficient; and (3) the analysis results after optimization can effectively reflect the actual values and have a wider range of applications than before the optimization. 2022 Vol. 59 (3): 201-210 [Abstract] ( 512 ) [HTML 1KB] [ PDF 4207KB] ( 930 ) 211 Analysis and Control of the Settlement of Super-large Diameter Shield Tunnel Passing under the Yellow River Embankment ZHU Muyuan1 WEI Lifeng1 FANG Yong1 FU Qiang2 GAO Tengda2 PU Song1 To reasonably control the settlement of the slurry shield with a super-large diameter in the process of tun? nelling under the Yellow River embankment, this paper carries out a case study on the Jiluo Road Tunnel Project passing under the Yellow River. Firstly, the parameters configuration was put forward for the shield passing under the embankment through theoretical analysis. Secondly, the pattern and characteristics were analyzed of settlement in the embankment section where the shield tunnel is passing through according to the field measured data. Thirdly,a numerical calculation model was established to accurately and dynamically simulate the excavation process of the shield tunnel and to analyze the impact of the shield parameters on the settlement of the Yellow River embankment according to the slurry pressure and grouting pressure. Finally, the transition schemes of excavation parameters were compared for the section of the embankment with variable slope. The results show that the initial speed of settlement in the embankment section is greater and more susceptible to disturbances in the phase of the shield tail leaving the segment, compared to the ordinary ground section, and the top of the embankment is more sensitive to disturbance from deep soil masses; In the process of passing under the embankment, it is conducive to settlement control to im? prove the tunnelling parameters of the shield tunnel, though with an upper limit to the degree of control, while adjusting the tunnelling parameters in advance would be beneficial to further reduce the settlement. Therefore, it is recommended to gradually increase the slurry pressure from 300~350 kPa to 500~550 kPa in the process of passing under the embankment and carry out parameter transition 10~15 rings in advance. 2022 Vol. 59 (3): 211-219 [Abstract] ( 553 ) [HTML 1KB] [ PDF 3363KB] ( 1048 ) 220 Research on Risk Assessment and Management Methods for Projects of Railway Tunnels Passing under Expressways TANG Yan This paper puts forward a quantitative risk assessment concept combined with numerical simulation analy? sis to address the risks of the high-speed railway tunnel project passing under an expressway. Firstly, a risk assessment index system is established by analyzing similar project experiences and taking into account the actual project context, and the overall system and inter-layer weights are ranked by the hierarchical analysis method. Secondly, on the basis of the numerical simulation results, a fuzzy comprehensive evaluation is made for the risk probability and consequences of the project, and the initial evaluation result of risks for the project is "moderate" risk. Finally, the corresponding risk control countermeasures are proposed for the main sources of risks, the risk reassessment is carried out according to the same procedure, and the result is "mild" risk, which indicates that the risk control measures are feasible and can provide guidance for the project. 2022 Vol. 59 (3): 220-226 [Abstract] ( 508 ) [HTML 1KB] [ PDF 2942KB] ( 997 ) 227 Research on the Characteristics of Structural Dynamic Response and the Seismic Mechanism of Mountain Tunnels with Different Depths YU Lingfeng Seismic studies have shown that damages could vary greatly to tunnels with different depths. In view of this, this paper analyzes the typical seismic characteristics and damage mechanisms at the tunnel portal area. By esablishing a 3D finite element numerical model, this paper is based on the soil-structure interaction with a focus on the ground seismic response of the tunnel structure in the shallow overburden area at the portal with different depths and the damage mechanism of the tunnel lining. The results show that the soil-structure interaction plays a controlling role in the force-induced deformation of the tunnel lining, and the shear force-induced deformation of the strata can directly reflect the deformation mode of the lining and the characteristics of the stratum vibration pattern. In addition, the force of the soil-structure interaction, the plastic deformation of the surrounding rock and the damage distribution of the lining structure all indicate that different areas, such as the side and foot of the arch, play a controlling role in the overall stability of the tunnel structure, and it is recommended that the surrounding rock in these areas be reinforced. 2022 Vol. 59 (3): 227-235 [Abstract] ( 557 ) [HTML 1KB] [ PDF 5200KB] ( 565 ) 236 Application of Digital Detonator Staggered-phase Vibration Abatement Technology in Railway Tunnels with Ultra-close Spacing WANG Lichuan1,2 ZHANG Xuemin2 WU Haibao3 ZHOU Xianshun2 LIAN Fasheng4 ZHANG Peng4 For the drainage gallery urgent remediation project of the Baiyanjiao Tunnel, where the non-blasting ex? cavation was making an extremely slow progress, the application of digital electronic detonator staggered-phase vibration abatement technology significantly improved the excavation progress and effectively controlled the impact of blasting (6.1 to 15.9 meters from the main tunnel structure) on the main tunnel. Based on four tests of continuously improved blasting schemes, the study determined the optimized design parameters of electronic detonator detonation in railway tunnels with (ultra) close spacing: the layout of double wedge-shaped cut holes followed the "symmetrical, double-layer, corresponding, confining and lifting" principles, with 0.9 kg charge for each hole and an interhole time delay of 7 minutes. It was also found that the seismic wave signal generated by the detonation of digital electronic detonator was dominated by ultra-high frequency bands (>200 Hz), and the higher the leading frequency was,the lower the vibration velocity would be. The leading frequency bands of vibration in the four blast tests showed a tendency toward a high frequency and a more even distribution, which could effectively avoid damage to the tunnel structure from low-frequency vibration. 2022 Vol. 59 (3): 236-245 [Abstract] ( 556 ) [HTML 1KB] [ PDF 4941KB] ( 673 ) 246 Research on the Dynamic Construction Technology of Slurry Shields Based on the Change of Geological Conditions LIU Hongzhi1,2 GAN Congyu1,2 ZHAO Liang1,2 ZUO Shirong1,2 ZHANG Hanshuo1,2 As the geological conditions in shield tunnelling are becoming increasingly complex, the current practice of determining the appropriate tunnelling parameters through "trial advancing" to guide the subsequent construction can no longer meet the requirements of shield tunnelling that passes through complex geological conditions in long distances. In view of this, this paper puts forward the concept of dynamic construction technology of the slurry shield based on the analysis of geological condition changes through the characteristics of mucks excavated by slurry shields. Based on the construction example of the slurry shield tunnel of Beijing South-to-North Water Diversion Project, which passes through sandy pebble strata with interlayered clay, the performance status and faced issues during shield construction are determined from five aspects, including geological analysis, geotechnical analysis,shield tunnelling parameters analysis, other factor analysis and comprehensive analysis. By this technical concept and method it can realize the real-time and professional control of the whole shield construction process to a certain extent, which is of great significance to ensure the safety and efficiency of shield construction. 2022 Vol. 59 (3): 246-252 [Abstract] ( 501 ) [HTML 1KB] [ PDF 4011KB] ( 642 ) 253 Study on Safety Control of Adjacent Construction of Overlapped Shield Tunnel with a Small Radius of Curve ZHANG Lili1 SHAN Lin1 GUO Fei1 CAI Zhen1 HAN Ruilin1 ZHANG Xu2,3,4 WANG Zhiguang2 XU Youjun2,3,4 The risk of the adjacent construction of overlapped shield tunnel with a small radius of curve is relatively high, so its safety control is of great importance in the industry. Based on the case of an overlapped shield tunnel project, the feasibility of control measures such as interlayer soil grouting, erection of internal steel supports, etc.was studied through numerical simulation, and a reasonable control scheme was proposed accordingly. In addition,the effect of safety control was evaluated according to the data of on-site monitoring. The study results showed that,compared with the scheme without reinforcement measures, the reinforcement through interlayer soil grouting could increase the strength of interlayer soil and effectively reduce the floating of segments, while the erection of internal steel supports were could reduce the horizontal deformation of segments. The combination of these two schemes could effectively maintain the shape of the section, and the maximum values of vertical deformation of segment crown and convergence deformation of horizontal clearance were 7.02 mm and 2.74 mm respectively, both of which were less than the standard value of deformation control. Therefore, the combined use of interlayer soil grouting and erection of internal steel supports on site was reasonable and feasible. 2022 Vol. 59 (3): 253-264 [Abstract] ( 551 ) [HTML 1KB] [ PDF 5726KB] ( 671 ) 265 Study on the Mechanical Behavior of the the Double-layer Arch Cover Initial Support during the Construction of Subway Stations by Arch-cover Method WEI Zhiyuan1 FENG Jimeng2 YU Longping2 The arch-cover method has been widely promoted and practiced, and extant studies have recognized the arch cover as the key to construction. However, there has been a lack of in-depth research on its mechanical behavior during construction by the arch-cover method. In view of this, based on the standard section of the Xiaogang Station on the west extension of Qingdao Metro Line No. 2, this paper studies the mechanical behavior involved in "doublelayer initial support arch-cover method" during construction by combining numerical simulation and field monitoring, with a focus on the mechanical effect when the temporary vertical bracing is removed. The results show that the double-layer arch-cover system makes full use of the bearing effect of the underlying hard rock and soil body to effectively control the ground settlement and surrounding rock deformation; Before the removal of the vertical bracing,the pressure on the arch is mainly borne by the temporary vertical bracing and the first layer of the arch cover; after the removal, the arch sank again, while the system underwent a stress conversion, and the two layers of the arch cover eventually enter a phase of synergistic work. The findings show that the double-layer arch-cover method meets the requirements of safe construction as verified in the construction of the Xiaogang Station, and makes it possible to realize the rapid and safe construction of the shallow large-span underground structure. 2022 Vol. 59 (3): 265-274 [Abstract] ( 594 ) [HTML 1KB] [ PDF 6966KB] ( 673 )

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