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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2022 Vol.59 Issue.4 Published 2022-08-25 1 Tunnel Excavation Review and Outlook Felix Amberg This paper presents major developments in underground construction over the past 40 years and puts them in the context of important projects. In addition to technical and technological developments, it also explains aspects that have had a significant influence on underground construction during that time. Finally, it also presents the challenges and necessities of future development. Guide:  2022 Vol. 59 (4): 1-6 [Abstract] ( 342 ) [HTML 1KB] [ PDF 1338KB] ( 841 ) 7 Reflection on Several Issues in Scientific Research on Loess Tunnelling LIANG Qingguo1 CHEN Kelin1 WANG Shang1 SHI Baodong1 ZHANG Tangjie2 Based on relevant research results from investigation of existing loess tunnel works, the author has com? pared the advantages, disadvantages and applicability of various research methods, summarized some complex issues in loess tunneling and underground engineering and put forward relevant counter solutions, mainly including surrounding rock classification method reflecting mechanical principle of dynamic construction under complex geological conditions, spatial-temporal evolution law and calculation method of surrounding rock pressure at tunnel portal, influence of water softening mechanism of loess on stability and durability of tunnel structure, deformation law and structural optimization of surrounding rock when the tunnel passes through the loess-bedrock binary stratum, optimal design of waterproof and drainage system of loess tunnel, reinforcement and protection technology of side and front slopes in bridge-tunnel connection project, ecological restoration and other engineering scientific problems. Guide:  2022 Vol. 59 (4): 7-17 [Abstract] ( 350 ) [HTML 1KB] [ PDF 1755KB] ( 737 ) 18 Study on the Structural Safety Assurance Technology and Strategy for Long and Large Highway Tunnels in Chongqing XU Pai1,2 ZHU Daiqiang1,2 JIANG Shuping1,2 XING Rongjun1,2 LI Liangliang1,2 Long and large highway tunnels are the core transportation infrastructure in Chongqing. In recent years, accidents relating to structural (facility) damage occur from time to time, so it is urgent to improve the operational safety and security capabilities. In this study, the accidents relating to structural (facility) damage to long and large tunnels in Chongqing were investigated, and the cause and form of accidents and risk sources were analyzed, the status of structural safety and security system was investigated and researched in terms of structural health maintenance and disaster-prevent and rescue system, the safety assurance system, measures, technical validity and real demands were defined, the difficulties and challenges suffered were analyzed, and the innovative operation management system and measures for disaster prevention and control, emergency rescue, etc. of long and large highway tunnels and the technical R&D and application were proposed in combination with emerging technologies. It is recommended to put forward three major action plans to build a secure guarantee system centered on "health monitoring/detection, advanced maintenance, smart disaster prevention, rapid emergency response, and comprehensive evaluation",help Chongqing become an international integrated transportation hub and a national (west China) science and tech? nology innovation center, promote the construction of a dual-city economic circle in Chongqing and Chengdu, and boost the safe development of our integrated three-dimensional transportation network. Guide:  2022 Vol. 59 (4): 18-28 [Abstract] ( 348 ) [HTML 1KB] [ PDF 1192KB] ( 535 ) 29 Review of the Research on Lining Damage and Repair Measures for Tunnels in Operation SHAO Zhushan1,2 XI Huihui2 QIAO Rujia1 ZHOU Hang2 GUO Yinbo1 Lining damage is one of the common and severe defects during the operation of tunnels and has an impact on the bearing capacity and stability of tunnel structure and the normal movement of pedestrians and vehicles to some extent. On this basis, the cause of lining damage, classification of cracks, and detection method and evaluation criteria for cracks were systematically investigated, researched and summarized in detail, the existing methods used for removal and repair of damaged linings were objectively evaluated, and the future research and development trend was discussed. The overview results showed that the lining damage accounted for 82% of the tunnel defects, and there were multiple causes of lining damage, including objective factors (e.g. complex geological conditions) and subjective factors in terms of construction and design. The lining damage was the result of several factors, rather than a single factor. The lining damage mechanism and classification method were further summarized, and according to a different stress mechanism and the crack characteristics, cracks could be divided into circumferential, longitudinal and diagonal cracks. The advantages and disadvantages of different methods for detecting damaged linings as well as the judgment criteria for cracks were sorted out to select an appropriate detection method for different situations.Based on the location and width of cracks, crack treatment measures for different situations were summarized, the experience in the prevention of relevant diseases was provided for the construction of tunnels, and the economic loss arising out of the repair and treatment of linings was reduced. Guide:  2022 Vol. 59 (4): 29-39 [Abstract] ( 372 ) [HTML 1KB] [ PDF 3156KB] ( 652 ) 40 Study on the Pattern of Hard Rock Damage and Constitutive Relation with the Microwave-Force Action HU Mengling YE Jiatong DAI Jun YANG Fan To apply microwave technology to rock fragmentation engineering as soon as possible, it is necessary to define the pattern of hard rock damage and constitutive relation with the microwave-force action. By introducing the D-P criteria and the Weibull distribution, a constitutive model of hard rocks with the microwave-force action is built, and through the microwave irradiation and uniaxial compression tests of hard granite, the pattern of microwave damage to hard rocks is explored and the constitutive model is verified. The study results show that the cracks in granite develop and the brittleness and strength are significantly reduced as the microwave power increases. At 4.0 kW,60% of the granite damage limit can be reached, and then the damage is not aggravated as power increases. Under the 1 min irradiation condition, the critical power of sample cracking is 3.33 kW and the critical power of melting is 5.33 kW. The unity coupling of the modified constitutive model is better, and especially for the section from the threshold value to the peak value, the coupling effect is extremely good, reflecting the conservatism with a high application value. Guide:  2022 Vol. 59 (4): 40-49 [Abstract] ( 325 ) [HTML 1KB] [ PDF 3801KB] ( 455 ) 50 Study on the Mechanisms of the Influence of Rock Mass with Previous Highstress Damage on Surrounding Rock Supports TANG Lei1 WEN Jiaqi1 ZHAO Xinming2 JIANG Bo2 ZHAN Qibing1,3 The rock mass in the fault zone is characterized by fissures and previous high-stress damage. To explore the mechanical property of rock mass with high-stress previous damage after excavation when a tunnel passes through a fault zone and its impact on supports, different discrete element numerical models of two unloading paths are designed: pre-peak unloading, reflecting the excavation of ordinary tunnels; post-peak unloading, reflecting the excavation of tunnels in the rock mass with high-stress previous damage in a fault zone. The calculation parameters of discrete element models are calibrated through the triaxial compression test of white sandstone samples, and then numerical calculations are conducted to compare and study the mechanical behaviors of surrounding rocks in these two unloading paths. The results show that the self-bearing capacity of the surrounding rock with high-stress previous damage collapses at a faster speed after excavation-induced unloading, so supports shall be provided more timely; the support strength required is significantly increased to achieve the identical amount of deformation of surrounding rock; and it is more difficult to support the micromechanism for the significant development of tensile microcracks. Guide:  2022 Vol. 59 (4): 50-57 [Abstract] ( 324 ) [HTML 1KB] [ PDF 4268KB] ( 527 ) 58 Service Status Evaluation for Shield Tunnels Based on Knowledge Graph ZHANG Hongfei1 WANG Xiaolong2 XUE Yadong3 ZHU Jingjing2 To accurately and reasonably evaluate the service status of urban metro shield tunnels, this paper puts for? ward a dynamic evaluation method for tunnel performance. The method includes two parts: (1) knowledge graph of shield tunnels; and (2) dynamic evaluation model of tunnel performance. The Knowledge Graph (KG) is used to integrate data related to shield tunnels and provide data support for the evaluation of shield tunnel performance. In terms of the performance evaluation model, the cumulative difference approach (CDA) is used to divide the tunnel into different segments of unequal lengths based on the lateral convergence deformation of the shield tunnel, taking into account various factors such as data scarcity, passages, and the influence extent of failures, and the segmentation results are adjusted through dynamic time warping (DTW); Based on the segmentation results, the static evaluation results of the shield tunnel′ s performance during multiple consecutive time intervals are used to calculate the rate and trend of changes in the performance. During the application of the method in Shanghai Metro Line 1, the model accurately identified homogeneous sections and tunnel cross-sections with different deterioration rates, and the KG also provided an effective approach for the application of the model. Guide:  2022 Vol. 59 (4): 58-68 [Abstract] ( 352 ) [HTML 1KB] [ PDF 4484KB] ( 665 ) 69 Study on Prediction of TBM Tunnelling Parameters Based on Attentionenhanced Bi-LSTM Model ZHANG Qinglong1,2 ZHU Yanwen1 MA Rui2 YAN Dong3 YANG Chuangen3 CUI Tonghuan3 LI Qingbin2 Prediction of TBM tunnelling parameters with Bi-LSTM model is subject to shortcomings in model training time and convergence speed. So, an intelligent prediction model of attention-enhanced bidirectional long-/shortterm memory network (Bi-LSTM+EMB_ATT) formed by parallel fusion was proposed by improving the use of traditional attention mechanisms, and the complete tunneling cycle data was selected to predict the tunneling parameters in the stable section of TBM. The operation data of TBM3 Section of Jilin Songhua River Diversion Project were collected and divided into a training set and a test set and preprocessed by the binary state discriminant function and other methods, and then the Pearson method was adopted to analyze the results. The 21-dimensional tunnelling parameters of the complete tunneling cycle section was used as the input of the prediction model to compare and analyze the parallel-connected Bi-LSTM+EMB_ATT model and serial-connected Bi-LSTM+ATT model. The results show that the goodness of fit of Bi-LSTM+EMB_ATT model for predicting TBM tunneling parameters is above 0.91 with average absolute error less than 2.7%, which is higher than that of Bi-LSTM+ATT model. Guide:  2022 Vol. 59 (4): 69-80 [Abstract] ( 357 ) [HTML 1KB] [ PDF 5846KB] ( 590 ) 81 Study on TBM Deviation Correction and Direction Control Based on the Deep Transfer Learning (DTL) HOU Kunzhou The full-section hard rock tunnel boring machine (TBM) is affected by different factors during tunneling, such as deadweight, geological conditions and human factors, resulting in a change in the tunneling posture and a deviation from the target axis, so derivation correction and direction adjustment to the target trajectory are required to ensure the quality of construction. A DTL-based TBM derivation correction and direction control method was put forward in this paper, i.e. the DTL neural network was used to build a parameter prediction model for TBM derivation correction and direction control, and then the TBM derivation correction and direction control position and posture model were analyzed to plan the derivation correction trajectory in combination with the maximum amount of movement of edge cutter and the minimum turning radius. The engineering verification results showed that the DTL-based parameter prediction model for TBM derivation correction and direction control model had a higher control accuracy which could confine the difference between TBM posture and target axis within ±20 mm, and the surface of tunnel walls was smoother, improving the quality of tunnel construction; the derivation correction trajectory was planned based on the maximum amount of movement of edge cutter and the minimum turning radius, and the derivation correction process was more controllable to avoid cutters and cutterhead from being damaged due to over-ad?justment and also reduce the risks of TBM jamming. Guide:  2022 Vol. 59 (4): 81-89 [Abstract] ( 316 ) [HTML 1KB] [ PDF 4410KB] ( 552 ) 90 Identification Method for Cracks in Tunnel Linings Based on Improved Chain Code Tracking Algorithm XU Xianlei1 ZHENG Haoxiang2 LIU Yuhao2 Apparent cracks in subway tunnel linings would pose direct threats to the safe operation of subway tun? nels. Most current detection techniques for lining cracks are based on image processing, and the detection efficiency and accuracy can hardly meet practical needs due to the large amount of image data to be processed and the complex internal environment of subway tunnels. In view of the above situation, a study has been conducted on the identification method for cracks in tunnel linings based on improved chain code tracking algorithm. Firstly, the apparent images of tunnel lining, obtained by the linear array camera, were processed in advance. Then, the identified cracks were converted into chain code sequences, before an improved chain code tracking algorithm was put forward which could quickly extract the special points in the crack boundaries and eliminate pseudo-inflection points and redundant inflection points. Lastly, based on the tree structure model of crack skeleton, algorithms for crack skeleton length and crack width, were proposed and an error analysis was carried out for the chain code tracking results. The results of field detection experiments show that the number of pixel points of the crack boundaries tracked by the improved tracking algorithm of chain code boundaries can be reduced by 82%, with the errors of crack length and width controlled within 4% and 7% respectively, under the premise that the crack shape remains unchanged. Therefore, this method can provide technical support for the rapid detection of cracks in tunnel linings and the safe operation of tunnels. Guide:  2022 Vol. 59 (4): 90-99 [Abstract] ( 332 ) [HTML 1KB] [ PDF 5628KB] ( 502 ) 100 Research on the Recognition Technology and APP for Sematic Segmentation of the Images of Drainage Hole Siltation by Crystals LIU Wenjian1 ZHANG Guocai2 LV Jianbing3 LIU Feng3 WU Weijun3 CHEN Gongfa3 In order to improve the detection speed for siltation of tunnel drainage holes by crystals and the accuracy of qualitative analysis of siltation degree, this paper explores and uses a convolutional neural network of semantic segmentation (DeepLab v3+ resnet18) to recognize the images of tunnel drainage holes. In this paper, the components in 230 drainage hole images were split into three categories: "crystal", "drainage hole wall" and "others". Furthermore, 138 images (60% of the total samples) were used to train the DeepLab v3+ resnet18 model, and the remaining 92 images (40% of the total samples) were used for image prediction. The results showed that the global accuracy based on this semantic segmentation model was up to 95%, and the prediction accuracy of crystals was over 75%, complying with the basic requirements for qualitative analysis of images of drainage hole siltation by crystals.In addition, this convolutional neural network of semantic segmentation was also self-programmed in MATLAB APP, so that staff could easily and conveniently detect (and predict) the images of drainage hole siltation by crystals. Guide:  2022 Vol. 59 (4): 100-107 [Abstract] ( 326 ) [HTML 1KB] [ PDF 4281KB] ( 478 ) 108 Thickness Calculation Method for the Insulation Layer of the Tunnel in Cold Region Considering Seepage and Fissures YU Jianyou1 JIANG Yifan2 LIN Ming2 LIU Jianqi1 CAI Libin2 JIANG Xinzheng2 WANG Zhijie2 ZHOU Ping2 The impact of fissures and seepage on the temperature field of tunnels in cold regions cannot be neglect? ed. Based on the Qipanliang Extra-long Tunnel in the Hebei section of the Yanqing-Chongli Expressway, a random fissure model considering seepage was built and the impact of various factors on the depth of tunnel freezing was explored so as to establish the calculation equation of insulation layer thickness. The research results showed that (1) the negative temperature section at the inlet of the tunnel in the coldest month was 172 m long, and the negative temperature section at the minimum temperature was 273 m; the negative temperature section at the outlet in the coldest month was 238 m, and the negative temperature section at the minimum temperature was 292 m; anti-freezing shall focus on the range of 300 m in the inlet section. (2) The existence of fissures had a non-negligible impact on the distribution of temperature fields, and due to the influence of "separation" of fissures, the tunnel section envelopes were nonuniform, and the maximum depth of frost appeared at the crown. (3) The depth of frost was negatively correlated with porosity, permeability, specific heat capacity and initial temperature of surrounding rocks and was posi? tively correlated with heat conductivity coefficient and heat transfer coefficient. The sensitivity of the depth of frost to various factors was ranked as follows: initial ground temperature > specific heat capacity > porosity > heat conductivity coefficient > heat transfer coefficient > permeability. (4) In the established calculation equation of insulation layer thickness, the impact of fissures and seepage was considered to get the insulation layer thickness (4.2 cm) in the inlet section and the insulation layer thickness (4.8 cm) in the outlet section. Guide:  2022 Vol. 59 (4): 108-117 [Abstract] ( 334 ) [HTML 1KB] [ PDF 4233KB] ( 457 ) 118 Study on the Distribution Pattern of Temperature Fields and Anti-freezing and Heat Preservation of Ventilation Shafts in High-altitude and Cold Regions WANG Jianjun1 YANG Linlin2,3 YANG Wenbo2,3 ZHANG Yifei2,3 Based on the ventilation shafts in the Dongliangdi Tunnel, on-site monitoring was conducted for the tem? perature field during the construction of ventilation shafts in a high-altitude and cold region, and the method of CFD simulation calculation was used to analyze the temperature field during the operation and to research the distribution pattern of the temperature field of shafts under different ventilation conditions and the cold-proof and thermal insulation measures. The analysis results showed that the impact of low ambient temperature on shafts during construction was relatively small due to the warm return air at the bottom of shafts, and when the return air at the bottom of shafts was beneficial to anti-freezing of shafts, exhaust shafts would also not be frozen during the operation. The surrounding rocks behind the whole blowing-in shaft were frozen to different degrees during operation and ventilation in winter, and the depth of frost was greatly affected by the time of ventilation and less affected by the velocity of wind, and the development of depth of frost became stable after 2 months of ventilation; the construction of insula? tion layers could reduce the changes in the temperature of surrounding rocks during operation, and after comprehensively considering various factors, it is recommended to pave a 6 cm-thick polyurethane insulation layer on the blowing-in shaft side of the projec. Guide:  2022 Vol. 59 (4): 118-126 [Abstract] ( 287 ) [HTML 1KB] [ PDF 4063KB] ( 522 ) 127 Analysis on Deformation and Failure Characteristics of Surrounding Rock in Horizontal Layered Tunnels under High Crustal Stress Based on 3DEC Simulation WANG Yaqiong1,2 YANG Qiang1,2 PAN Hongwei3 GAO Qidong1,2 ZHANG Shichao1,2 WANG Zhifeng1,2 In order to thoroughly study the characteristics of deformation failure in surrounding rock of horizontal layered tunnels under high crustal stress environment, the crustal stress test results and the deformation failure of surrounding rock were analyzed based on engineering background of Yunnan Zhaotong-Leshan Expressway Jiaoding Tunnel. The 3D discrete element (3DEC) numerical simulation method was adopted to study the deformation failure laws of surrounding rock under the conditions of different rock thickness d, crustal stress level s and lateral pressure coefficient k. Moreover, the stress characteristics and deformation failure mechanism of surrounding rock of horizontal layered tunnel were discussed as well. The results show: the deformation of horizontal layered surrounding rock is symmetrically distributed along the central axis of the tunnel. The displacement of surrounding rock is the largest where the joint direction is tangent to the tunnel contour, but is the smallest where the joint direction is orthogonal to the tunnel contour; With the increase of layer thickness, the displacement of surrounding rock of the tunnel decreases gradually. The displacement changes faster when the thickness is 0~0.3 m, slows down when the thickness exceeds 0.3 m, and basically tends to be stable when the layer thickness reaches 3.0 m; The displacement of tunnel surrounding rock increases gradually with the increase of crustal stress, and the change rate remains stable; The displacement of tunnel surrounding rock increases gradually as function of lateral pressure coefficient, and the displacement change is the most significant at the arch waist. In the crustal stress environment, severe compression deformation may occur even if rock strength is great, in case the layered joints of the surrounding rock are developed, which shows the characteristics of great deformation in soft rock. Guide:  2022 Vol. 59 (4): 127-136 [Abstract] ( 332 ) [HTML 1KB] [ PDF 4315KB] ( 593 ) 137 Discussion on the Timing for the Secondary Lining Construction in Soft Ground Tunnels with High Geostress Based on Numerical Simulation and Measured Data Fitting MA Dong JIN Liujie WANG Wuxian HUANG Lixin The large deformation control for soft ground with high geostress in the railway tunnel is always a difficult problem in construction. Due to the uncertainty about deformation pattern and deformation time and the complexity of deformation mechanism, the timing for constructing the secondary lining in a high geostress environment has been a problem for construction personnel. For this reason, the large deformation pattern was studied combined with measured field data and numerical simulation and the timing of the secondary lining construction of the high geostress soft ground tunnel was discussed. The study results show that (1) the optimal timing for the construction of the secondary lining should be determined by using the dual control method of amount of deformation and rate of deformation, especially severe and extremely severe deformation sections. The secondary lining cannot be constructed until the amount of deformation reaches 95% of the estimated amount of deformation, the rate of crown settlement does not exceed 0.4 mm/d, and the rate of convergence of sidewall does not exceed 0.6 mm/d; (2) The relevance of exponential function fitting and time-history curve of deformation is high. In view of the complexity of tunnel surrounding rock, uncertainty of construction parameters and errors in measured data, it is not feasible to use a particular parameter for deformation curve fitting of all tunnels; and (3) in the analysis of construction timing for the secondary lining of tunnels prone to large deformation, the selection of creep parameters should be comprehensively considered according to stratum lithology and measurement results of adjacent strata. Guide:  2022 Vol. 59 (4): 137-146 [Abstract] ( 324 ) [HTML 1KB] [ PDF 4850KB] ( 674 ) 147 A Study on the Long-term Effect of Grouting Treatment for Large Transverse Deformation of Shield Tunnels in Soft Soil MOU Gongyu1 ZHANG Dongmei2 This paper aims to address the problem that the long-term mechanism of grouting treatment for large transverse deformation of shield tunnels is still unclear. Based on the case of grouting treatment for the Shanghai metros and taking into considertation the coupling effect of water and soil, numerical simulations of different grouting methods are conducted by using the virtual swelling stress method. The study reveals the dissipation mechanism of excess pore water pressure and the deformation mechanism of the tunnel during the consolidation stage and unveils the patterns in the effects of excess pore water pressure dissipation on the long-term efficiency of grouting. It is found that the dissipation of excess pore water pressure could be divided into two modes: the diffusion of local excess pore pressure and the drop of the overall excess pore pressure, and different dissipation modes will have different effects on the tunnel deformation. The recovery of transverse deformation of the tunnel is relatively stable at the early stage of consolidation, and as the excess pore water pressure decreases, such recovery will enter a rapidly rebounding stage after 10~30 days of consolidation, and gradually decelerate to stability after about 100 days. The distribution pattern of the excess pore water pressure caused by grouting is the most significant factor that affects the long-term efficiency of grouting. Therefore, improving the grouting method as a way to improve the distribution of excess pore water pressure generated by grouting can effectively improve the long-term effect of grouting treatment for transverse tunnel deformation. Guide:  2022 Vol. 59 (4): 147-157 [Abstract] ( 288 ) [HTML 1KB] [ PDF 3421KB] ( 563 ) 158 A 3D Numerical Simulation Study on the Ventilation of T-Shaped Tunnels with Different Bifurcation Angles during Construction LI Weilin1 ZHANG Guang1 ZHU Yingwei1 HU Shaohua1,2 To investigate the influence of the bifurcation angle on the diffusion of blasting gas in T-shaped tunnels built by the drilling and blasting method, this study, on the basis of the bifurcation structure formed by the left main tunnel and 38# cross tunnel in the Yuelongmen Tunnel on the Chengdu-Lanzhou Railway, establishes the 3D mesh models with bifurcation angles of 45°, 60°, 75° and 90° respectively, carries out numerical simulations of the tunnel ventilation by using Fluent and, taking into account the local loss theory, investigates the pattern of wind energy loss at the bifurcation. The results show that in the process of ventilating for the construction of T-shaped bifurcated tunnels, a large ventilation blind zone appears near the side of the obtuse angle of the cross tunnel and the downstream side of the main tunnel without bifurcation, and the range of the blind zone expands with the increase of the bifurcation angle. Comparing the time required to discharge the blasting gas under each construction condition, it is found that the larger the bifurcation angle of the tunnel is, the worse the ventilation effect will be, and the longer the required time will be for ventilation. Through the deduction of the relationship equation between the local loss coefficient and the bifurcation angle, it is also found that the local loss coefficient of the main tunnel is almost independent of the bifurcation angle, while the local loss coefficient of the cross tunnel is positively correlated to the bifurcation angle of the tunnel. Guide:  2022 Vol. 59 (4): 158-166 [Abstract] ( 357 ) [HTML 1KB] [ PDF 3848KB] ( 566 ) 167 Analysis on the Reliability of Metro Deep Foundation Pit System under Multiple Failure Modes WU Xianguo1 WANG Lei1 FENG Zongbao1 QIN Yawei1,2 QIN Wenwei1 In order to analyze the variation pattern of reliability indicators of deep foundation pit under different correlation coefficients of soil shear strength parameters, the failure functions were established for anti-sliding stability,anti-overturning stability and anti-uplift stability of deep foundation pit, respectively, based on Copula theory and in combination with the modeling process of single failure mode. Then, the failure reliability of deep foundation pit system based on Copula theory was analyzed in series. The application results show that: anti-sliding stability and anti-uplift stability account for a major part of the system stability, while anti-overturning stability only accounts for a small part; Reliability indicators of the system under each failure mode may change significantly as function of the correlation of shear strength parameter, which proves that the influence of parameter correlation cannot be ignored in reliability design; Different copula functions have a great impact on reliability calculation. So, it is necessary to fit and optimize the distribution of parameters. The failure probability of the project may be underestimated if it is directly assumed that the parameters follow Gaussian distribution. Guide:  2022 Vol. 59 (4): 167-175 [Abstract] ( 305 ) [HTML 1KB] [ PDF 3863KB] ( 528 ) 176 Development and Application of Test Loading System of Multi-ring Shield Segment Prototype WEI Gang1,2 ZHOU Xinxin3 LIU Yayu4 HUANG Shiyu3,5 FENG Feifan3 To address the various problems related to shield segments, such as the impossibility of real simulation of the stress of shield segments with the extant segment testing system and the low sustainable utilization rate of equipment, this paper carries out preliminary research on and theoretical calculation and on-site measurement of shield tunnel segments with the objective to make further improvement to existing tests of large full-scale segments. This paper proposes a new full-scale test loading method for shield segments and innovatively develops a multi-ring prototype test loading system of shield segments. This system takes three-ring lining segments as the test subject and simulates the stress and deformation of the middle-ring segment under different working conditions of ground eccentric stacked loads. The test results show that the value of the bending moment of the segment increases with the increasing eccentric load, and the range of the positive bending moment region at the bottom is about twice the positive bending moment region at the top. Also, the efficiency of the bending stiffness of the segment increases linearly,while the bending moment transmission coefficient of the joint keeps decreasing, and the segment will be deflected as a whole under the eccentric load. Guide:  2022 Vol. 59 (4): 176-186 [Abstract] ( 321 ) [HTML 1KB] [ PDF 6366KB] ( 505 ) 187 Test Study on the Reinforcement Effect of Bonding Steel to Damaged Tunnels under the Lateral Loads LIU Xuezeng1 GU Wenchuan1 YANG Zhilu2,3 GUO Qiaokun4 HE Guohua5 FENG Jin6 To research the reinforcement effect of bonding steel to the damaged linings of tunnels under lateral loads, a 1∶10 model test was conducted, and the modes of deformation and damage of the tunnel lining structure under lateral loads and the steel-bonded structure in different states of damage were researched. The test results showed that under lateral loads, the damage mode of the tunnel lining structure was brittle failure, and the damage development process was as follows: arch waist cracking — brittle shear failure of arch shoulder — damage to arch waist ductility and bending; damage was concentrated on the crown of the lining structure and the side wall-waist on the left and right sides, and the section stiffness was rapidly attenuated, which was the vulnerability and dangerous point of the structure; after steel was bonded for reinforcement, the stripping of bonded steel caused by the shear stress of the bonding surface at the structure waist was the major factor causing the instability of the reinforced structure; when the remaining bearing capacity proprtion was 30%, the bearing capacity of the structure reinforced by bonded steel was not increased; when the remaining bearing capacity proprtion was 48%, the bearing capacity of the reinforced structure was increased by 4.1%; when the remaining bearing capacity proprtion was 60%, the bearing capacity of the reinforced structure was increased by 10.2%. Consequently, after the damaged tunnel lining was rein? forced with bonded steel under the lateral pressure, the bearing capacity was not significantly improved and the reinforcement effect was limited, and the lining damage caused by lateral loads should not be reinforced by bonding steel. Guide:  2022 Vol. 59 (4): 187-195 [Abstract] ( 325 ) [HTML 1KB] [ PDF 4116KB] ( 515 ) 196 Sidewall Decoration for Highway Tunnels Based on Driving Comfort YE Fei1 ZHANG Xingbing1 SU Enjie1 WEN Xiaobao1 XIA Tianhan1 WEI Yanchun2 Proper landscape of highway tunnels can effectively alleviate the changes in the driving environment and a driver's discomfort, thus improving the safety and comfort of driving. This paper adopts the method of driving simulation test and uses eye movement and heart rate indexes as the evaluation criteria to evaluate and investigate the comfort and safety of tunnel landscapes from a dynamic perspective. The rationality of this evaluation method is verified through the design of three different landscape models by changing the sidewall decoration inside the tunnels.The results show that the evaluation method of driving simulation test combined with eye movement and heart rate indexes is very applicable to the evaluation of tunnel landscape. The 3 decoration schemes have outstanding effects on driving comfort, but their effect on driving safety is insignificant. All the different schemes would increase the instantaneous load. Specifically, the whitewash scheme has the highest instantaneous load, and the blue sky with clouds scheme has the lowest instantaneous load. None of the 3 schemes would lead to safety issues. Guide:  2022 Vol. 59 (4): 196-203 [Abstract] ( 332 ) [HTML 1KB] [ PDF 2312KB] ( 468 ) 204 Design and Engineering Application of Prefabricated Structure for Secondary Lining Arch of Double-Track Railway Tunnels Constructed by the Mining Method ZHOU Xiaojun1 NING Yuansi2 YANG Changyu3 Tunnel construction through the mining method with cast-in-place concrete lining often fails to complete? ly eliminate common quality defects, such as insufficient thickness of concrete lining, insufficient strength, cracking and spalling, and void behind in tunnel arch, which poses threats to the long-term safe operation of railway tunnels.This paper relies on the Hujiagou Tunnel Project of the East Ring Line of Chongqing Railway Hub and proposes to use assembled secondary lining for the arch of the composite lining by combining prefabricated blocks and sidewall molded lining. This paper analyzes the blocking method and joint structure of the prefabricated lining in the arch,summarizes the construction process and economy of the prefabricated lining structure, and analyzes the safety and durability of the lining structure according to field monitoring results. The results show that the structural parameters of the initial support and assembled secondary lining designed for the prefabricated lining test section of the arch of the Hujiagou Tunnel are feasible, and the lining allows for sufficient safety; The form of joints for the prefab? ricated lining of the arch and the cast-in-place sidewall should be designed in the form of a circular arc; The total cost of the scheme of secondary lining with prefabricated arch increases by RMB 3,147,100 compared with the total cost of the cast-in-place secondary lining, and the comprehensive cost increases by RMB 28,600/m. Guide:  2022 Vol. 59 (4): 204-217 [Abstract] ( 331 ) [HTML 1KB] [ PDF 5802KB] ( 602 ) 218 Design and Analysis of the Tunnel Section at Railway Station Crossing Under the Pile Foundation YANG Xiong1 MENG Qinghui2 LI Pin1 XU Dengfei3 CAO Feng1 Based on the case of the Large-span Tunnel Section at Longdongbao Airport Station (Guiyang Railway Hub) crossing under the airport viaduct and the theory of punching shear failure cone of rock mass, the method for determining the minimum rock slab thickness that meets the pile foundation stress requirement was put forward by using theoretical analysis, numerical simulation and field measurement; the standard for dividing the tunnel-pile foundation proximity relationship was established, in which the surrounding rock disturbance range of tunnel excavation and the range of punching shear failure of pile foundation were considered; and the viaduct settlement control standard and design countermeasures were proposed and the measured data were used for verification. The results show that the zone of influence of the tunnel crossing under the file foundation is reasonably divided, the design countermeasures can effectively control the impact of tunnel excavation on the viaduct, and meanwhile, the impact of pile foundation on the tunnel can be controlled. Guide:  2022 Vol. 59 (4): 218-225 [Abstract] ( 336 ) [HTML 1KB] [ PDF 4909KB] ( 516 ) 226 Research on the Technology for the Shield Tunnel Crossing the Railway Marshalling Station in the Pebble-boulder Stratum LIU Zhaowei When a shield tunnel crossing under an operating railway line is constructed in the pebble-boulder stra? tum, safety protection measures shall be taken to reduce the impact on the normal operation of the railway. Taking as an example the running tunnel project from Yushuzhuang Station to Wanpingcheng Station in Line 16 of the Beijing Subway crossing Fengtai West Railway Marshalling Station, the difficulties in construction were systematically analyzed, the measures for the shield tunnel crossing the railway marshalling station (e.g. cutter optimization and modification, muck conditioning scheme, and setting of tunneling parameters) were described, the key points and technological processes of protective measures for the railway (e.g. grouting reinforcement and rail fastening) were introduced, FLAC 3D was used to simulate the full process of shield tunnel crossing, and the effectiveness and necessity of engineering protection measures were analyzed. The calculation results showed that the grouting reinforcement that was carried out for the soil layer above which the shield tunnel crossed the regional railway could effectively block the upward transfer of shield construction disturbances, and after reinforcement, the vertical surface deformation was significantly reduced, and the railway line deformation was controlled within the safety range, which veri? fied the validity of engineering protection measures. 2022 Vol. 59 (4): 226-233 [Abstract] ( 360 ) [HTML 1KB] [ PDF 3911KB] ( 519 ) 234 HUANG Hui TANG Yongmao CAO Saisai 2022 Vol. 59 (4): 234-239 [Abstract] ( 312 ) [HTML 1KB] [ PDF 4393KB] ( 553 ) 240 Advance Grouting Reinforcement Technology for Earth Pressure Shield Tunnelling through Upper-Soft-Lower-Hard Strata LIU Hongliang1 ZHANG Bangchao2 GUO Jia2 JIAO Yefei2 ZHANG Min2 2022 Vol. 59 (4): 240-247 [Abstract] ( 281 ) [HTML 1KB] [ PDF 5332KB] ( 534 ) 248 Study on Treatment-after-passing Technology for Large Karst Cave below High-speed Railway Tunnel CHEN Wenyin When the high-speed railway tunnel is excavated in the karst development area, the influence of large karst cave below on tunnel construction cannot be ignored. In view of construction difficulty in bottom large karst cave encountered in Wangzhuang Tunnel of Nanning-Chongzuo Railway, the "treatment-after-passing" construction technology was proposed to deal with the karst cave below by using the methods of numerical simulation and model test analysis on the basis of high bearing capacity characteristics of limestone, as shown below. The foot-locking bolts and arch anchor cables will be added after completion of upper bench, and the lower support structure will be lifted. The tunnelling process will continue, and the muck will be quickly used to backfill the karst cave below.When there is no interference between the construction area and the karst cave treament area the karst cave roof will be exposed in the lower bench and the permanent treatment will be conducted for the karst cave. Raft and pile foundation is adopted to treat the large karst cave below to form a "pile-slab structure" to reduce the impact of the karst cave on the tunnel operation. This karst tunnel construction technology effectively reduces the impact of karst tunnel treatment on construction progress and ensures construction safety and quality. So, it provides a useful reference for similar projects. Guide:  2022 Vol. 59 (4): 248-255 [Abstract] ( 255 ) [HTML 1KB] [ PDF 3710KB] ( 446 ) 256 CHEN Jian1,2，3 SU Xiuting3,4 HUANG Xixi4 LIU Tao3,5,6 2022 Vol. 59 (4): 256-264 [Abstract] ( 226 ) [HTML 1KB] [ PDF 3164KB] ( 568 ) 265 Study on the Optimization of Admixtures Based on the Impact of Silica Fume on the Water Dispersion Resistance of Grouting Materials ZHANG Wenhong1; LIU Yingjing2; WANG Junqi2; LI Haoran2; SUN Kuizhu2; ZHU Hanhua2 To explore the impact of silica fume on the water dispersion resistance of synchronous grouting materials in water-bearing strata and optimize the compound admixtures of grouting materials, synchronous grouting materials in 5 groups of different silica fume contents and 6 groups of different amounts of compound admixtures of silica fume/polyacrylamide (PAM)/hydroxyethyl cellulose (HEC) are prepared for the tests of consistency, fluidity and extension, setting time and water dispersion resistance. The results show that the addition of silica fume, HEC and PAM increases the consistency of synchronous grouting materials but reduces the fluidity; PAM can reduce the slurry fluidity to a greater extent and silica fume can decrease the time-dependent loss of slurry fluidity; and silica fume accelerates the setting of synchronous grouting materials and increases the early strength of slurry. The results of pH value, anti-scouring and underwater/in-air strength ratio tests show that the addition of the three types of materials can significantly improve the water dispersion resistance of synchronous grouting materials. When the content of silica fume is 1.0%~2.0%, the PAM content is 0.05% and the HEC content is 0.20%~0.30%, the consistency, fluidity, setting time and water dispersion resistance of synchronous grouting materials can achieve better results. Guide:  2022 Vol. 59 (4): 265-272 [Abstract] ( 219 ) [HTML 1KB] [ PDF 1866KB] ( 496 ) 273 Assembly Force and Waterproofing Performance of Segment Sealing Gasket in High Water Pressure Shield Tunnels WEN Yanxin1 HUO Yongpeng2 WU Yue2 CHANG Xin1 ZHANG Tian2 YAN Qixiang2 To investigate the assembly force and waterproofing performance of segment sealing gaskets in high water pressure shield tunnels, this paper analyzes the major factors that affect the characteristics of gasket deformation,the growth law of assembly force, and the water-resistant pressure of seven sealing gaskets with different cross-setional forms in different compression stages, based on the Shangyuanmen Cross-river Tunnel Project and through different means such as assembly force test, water pressure test and numerical simulation. The results show that the compression process of the gaskets can be divided into three stages: Stage I when the sealing assembly force increases almost linearly; Stage Ⅱ when the increase of the assembly force slows; and Stage Ⅲ when the compression increases rapidly to the maximum assembly force. The greater the maximum assembly force and maximum compression of the gaskets are, the higher their water-resistant pressure will be, the more steadily their assembly force would increase with the growth rate of compression, and the more conducive it will be for their waterproof performance. For different cross-sectional forms and under the same groove form of the segment, the higher the height of a gasket is, the greater its maximum compression will be in general, and the greater the assembly force will be when the shield segment joint is completely closed. Furthermore, the triangular closed-hole type is better than other hole types, and gaskets with a whole rubber joint on the bottom are better than those with a comb-tooth structure on the bottom. Guide:  2022 Vol. 59 (4): 273- [Abstract] ( 306 ) [HTML 1KB] [ PDF 5352KB] ( 488 )

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