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Quick Search     Advanced Search MODERN TUNNELLING TECHNOLOGY   2023 Vol.60 Issue.6 Published 2023-12-25 1 Concept and Reflection on Low-carbon Development of Traffic Tunnel Engineering Based on Digital Technology ZHU Hehua1,2,3 DOU Shiqi1 SHEN Yi1,2,3 RUI Yi1,2,3 LI Xiaojun1,2,3 To accomplish the dual carbon goals, low-carbon or even zero-carbon development is the inevitable ap? proach for traffic tunnel engineering, and the digital transformation brings both opportunities and challenges in this regard. The intelligent infrastructure service system affords a strong digital base for low-carbon development of traffic tunnel engineering in terms of information acquisition, transmission, processing, analysis, expression and service process. The cutting-edge technologies such as big data, cloud computing, blockchain and artificial intelligence bring new momentum for comprehensive survey, dynamic design, intelligent construction and efficient O&M in traffic tunnel engineering. The research into low-carbon tunnel is still in its early stage, the relevant standard system is not established yet, the development objectives of low-carbon and zero-carbon tunnels, the object of digital empowerment and the implementation approach are still unclear, and the relevant top-level design theory needs to be further investigated. This paper offers a preliminary analysis on the carbon emission characteristics of traffic tunnel engineering, a retrospect of the digital technologies that have been successfully applied in the full life cycle of tunnel projects, and also an outlook on the prospect of digital technologies in low-carbon tunnel development. In the future,the late-mover advantage should be exploited in development of low-carbon tunnel, and the digital technologies and the green low-carbon development concept should be intensively integrated, so as to enhance the level of digitization in traffic tunnel engineering and also steadily accomplish carbon neutrality in traffic tunnel engineering industry. 2023 Vol. 60 (6): 1-10 [Abstract] ( 396 ) [HTML 1KB] [ PDF 5554KB] ( 944 ) 11 Study on Carbon Emission Characteristics and Emission Reduction Approaches in the Full Life Cycle of River-crossing Shield Tunnels AI Qing1 LI Yixuan1 ZHU Junyi2 The river-crossing tunnel is an important traffic infrastructure in the urban traffic network and one of the main sources of carbon emission in urban traffic, so it is necessary to investigate carbon emission measurement and assessment of river-crossing tunnels and emission reduction mechanism. The first step is to establish the carbon emission measurement boundary and list for the full life cycle of river-crossing tunnels. The life cycle is divided into two parts, i.e. materialization stage and O&M stage. Based on the list analysis, the carbon emission measurement model for the full life cycle of river-crossing shield tunnels is created based on the carbon emission factor method,the correlation between the full life cycle of river-crossing tunnels and the engineering activities is systematically analyzed, and the river-crossing tunnel carbon emission reduction effect estimation process driven by green technologies is devised. The carbon emission result is represented by using the carbon emission reduction effect coefficient. As the study indicates: there is severe lack of quantitative research into the carbon emission reduction effect of various green technologies both at home and abroad. In the materialization stage, the unit carbon emission of shield tunnel increases as the tunnel diameter increases, and there is only limited potential of carbon emission reduction as long as the material and structural design remain unchanged. In the O&M stage, the carbon emission of mechanical and electrical installations is largely equivalent to the carbon emission in the materialization stage. From the aspect of full life cycle, the O&M stage has greater potential of carbon emission reduction and better controllability. 2023 Vol. 60 (6): 11-19 [Abstract] ( 342 ) [HTML 1KB] [ PDF 2990KB] ( 575 ) 20 Calculation and Composition Assessment of the Carbon Emission in the Construction Phase of Highway Tunnels Based on SimaPro LI Jiahao1 XI Mingxing2 SHEN Yi1 LIU An2 ZHU Hehua1 In order to accurately and quantitatively calculate and assess the carbon dioxide emission during the construction phases of highway tunnels and ascertain the main sources of carbon emission and their influencing mechanisms, a standard calculation process, based on the life cycle assessment (LCA) method, is devised that covers the aspects including highway tunnel carbon emission calculation boundary, list analysis and calculation model creation. By using engineering examples and the life cycle assessment tool SimaPro, the carbon emission per linear meter of tunnels built under various surrounding rock conditions is calculated and analyzed. According to the results, the carbon emission per linear meter of tunnel increases markedly in the material production stage and construction stage as the surrounding rock is degraded. In highway tunnel construction, the carbon emission in the material production stage takes the largest proportion, particularly the carbon emission in the secondary lining material production stage takes a high proportion. Therefore improvement of the material production technology and research into carbon emission reduction design of lining structure are the key approaches to reducing total carbon emission in highway tunnel construction. 2023 Vol. 60 (6): 20-28 [Abstract] ( 367 ) [HTML 1KB] [ PDF 4805KB] ( 722 ) 29 Study on the Carbon Emission Prediction Model for Railway Tunnel Construction Based on Machine Learning ZENG Hongrui1,2 SUN Wenhao3 HE Wei3 GUO Yalin1,2 GUO Chun1,2 In order to build the algorithm model for carbon emission prediction during railway tunnel construction, a study has been conducted based on a railway tunnel project. First, the carbon emission during construction of the tunnel and the proportion of each subphase in the total emission are quantitatively determined by using the carbon emission calculation system. Then several different prediction models are created by using several machine learning algorithms, the parameters of the prediction models are optimized by using the animal optimization algorithm, the fitting results are compared and analyzed by using the assessment indicators including R2, MAE, MSE, RMSE, MAPE and SMAPE so as to select the optimum prediction model, and the importance degree of each parametric variable is determined by using the SHAP value. The results are stated as follows: The construction materials production stage has the greatest contribution to carbon emission in tunnel construction and the construction materials transportation stage has the least contribution; BP neural network generates better regression results than the algorithms such as random forest, LightGBM, SVR and extreme learning machine, and according to comparison of the regression prediction models optimized by the PSO, WOA and SSA algorithms, WOA-BP algorithm generates the best fitting results;based on the analysis by the SHAP algorithm, the rank of the parametric variables in terms of importance degree is as follows: excavation area > surrounding rock class > excavation method > buried depth. 2023 Vol. 60 (6): 29-39 [Abstract] ( 418 ) [HTML 1KB] [ PDF 4811KB] ( 645 ) 40 Analysis of the Effect of Lighting on Carbon Emission in the Full Life Cycle of Highway Tunnels Zhang Xiaoying1 Liu Tao2 Shen Yi2 Liu An3 : In order to address the global climate change, China has announced the decision to increase its nationally determined contributions and implement more effective policies and actions to reach carbon peaking and carbon neutrality. Construction, operation and maintenance of tunnel projects will generate huge amount of carbon emission, so accurate quantitative analysis and assessment of carbon emission will be important for achieving the dual carbon goals. The tunnel carbon emission boundary has been identified by using the LCA method, and the carbon emission calculation model for the full life cycle of tunnels has been established. Based on an actual project, the carbon emission in the full life cycle of tunnels has been calculated and assessed. According to the results, the carbon emission in the tunnel construction stage is mainly generated by materials production, and the carbon emission in the O&M period is closely related to the tunnel length. Based on the energy consumption proportion of the lighting section of the tunnels of various lengths, it is deduced that the proportion of lighting induced carbon emission in the middle section of tunnel increases as the tunnel length increases. The lighting design of tunnel is related to the traffic volume, so an uncertainty analysis of tunnel lighting energy consumption has been conducted by using the particle swarm optimization, with the traffic volume variation taken into account. As the results indicate, in a 500~4 000 m long tunnel, the carbon emission generated by the lighting energy consumption in the entrance section zone takes a significant proportion in the lighting section and this means great potential of energy conservation and emission reduction. 2023 Vol. 60 (6): 40-47 [Abstract] ( 318 ) [HTML 1KB] [ PDF 3436KB] ( 663 ) 48 Analysis of Traffic Flow in Highway Tunnel under the Coupled Effect of Ventilation and Luminous Environment HU Yongyong1,2 XI Mingxing2 LIU An2 HUANG Guanlin3 WU Yan3 RUI Yi3 The tunnel ventilation simulation program and tunnel luminous environment simulation model have been created, in order to investigate how multi-system integration will affect the driving behaviors of drivers in tunnel.Tunnel ventilation simulation is underlain by the tunnel one-dimensional pollutant concentration distribution function. The finite-element numerical solution program for tunnel pollutants concentration distribution is created by using the MATLAB software, so as to determine the pollutant concentration distribution in tunnel. CO and smoke are used as typical pollutants to investigate the mechanism by which pollutants affect driving behaviors, and to establish the quantitative evaluation criteria. Qualitative analysis is conducted by using the state of health of the driver as a criterion for CO concentration assessment, and visibility and driver′s response time are used as the criteria for assessing the impact of smoke. In the tunnel luminous environment model, the tunnel interior scene is created by using the Unity3D platform and virtual driving test is conducted by using the VR device, so as to analyze the driving behavioral patterns in various luminous environments. This study generates a model which reveals how tunnel luminous environment will affect driving behavioral patterns. The results of simulation can be used as reference in rationally designing the ventilation and lighting systems of tunnel and achieving energy-efficient operation of tunnel. 2023 Vol. 60 (6): 48-57 [Abstract] ( 375 ) [HTML 1KB] [ PDF 3739KB] ( 606 ) 58 Study on the Carbon Emission Characteristics and Carbon Emission Reduction Model in the Sewage Treatment Process in the Tianshan Shengli Tunnel Construction Area YIN Yan BAO Weixing LU Hanqing ZHANG Zhiyong CHE Bowen PAN Zhenhua LIN Xuhui In order to reveal the carbon emission characteristics in the sewage treatment process during construction of super-long tunnel, the sewage treatment process in the construction area of Tianshan Shengli Tunnel of UrumqiYuli Expressway is used as an example in this study, and the full life cycle method, process analysis method and pollutant parameters normalization method are used to create the new hybrid life cycle carbon emission calculation model for the sewage treatment process. Depending on the carbon emission footprint in the sewage treatment process, the carbon emission generated in the sewage treatment process is classified into direct emission and indirect emission, and its qualitative analysis and quantitative analysis have been conducted. The results indicate: in 2021~2022, the total carbon emission generated in the sewage treatment process in the construction area of Tianshan Shengli Tunnel was 4 242.43 tCO2eq, and the emission intensity was approx. 1.17 kgCO2eq/t; among the total carbon emission, the processes including electricity consumption, removal of BOD5, materials consumption, removal of TN and sludge transportation/disposal account for 85.3%, 11%, 2.1%, 1% and 0.6% respectively; by raising the quality standard for outlet water and using the sludge as fertilizer for soil for the purpose of energy conservation and emission reduction, the annual average carbon emission is reduced by approx. 15.6%, which brings about significant carbon emission reduction. 2023 Vol. 60 (6): 58-67 [Abstract] ( 309 ) [HTML 1KB] [ PDF 3820KB] ( 925 ) 68 Optimization of Method Statement for Low-carbon Tunnel Construction Based on SVM-MAUT LIU Shihao1 SONG Zhanping1,2,3 XU Leilei4 XIA Zhenzhao5 WANG Junbao1,2,3 To accomplish the dual carbon goals, it is urgently necessary to optimize the method statement for lowcarbon tunnel construction. With the help of the comprehensive evaluation system supported by multi-attribute de? cision-making, the to-be-evaluated stability indicators for tunnel construction in various scenarios have been examined, and 3 factors, i.e. surrounding rock stability, stratum stability and support stability, have been identified.Regarding the non-stability indicators, priority is given to the carbon emission non-stability factor, and the comprehensive evaluation indicator system for method statement for low-carbon tunnel construction is established. A mapping model is created that is based on the Support Vector Machine-Multi-Attribute Utility Theory (SVM-MAUT), in order to replace the traditional comprehensive evaluation method and find the low-carbon tunnel construction method statement comparison method. In the last step, the comparison method is applied to optimization of the construction method for the soft rock section with rock breakage and large deformation in Daliangshan Tunnel No. 1. Based on the attribute utility of the method statements for the basalt, claystone and silty mudstone sections, the optimum combination of method statements is identified. Compared with the method statement that generates extreme carbon emission, the carbon emission equivalent per linear meter is reduced by 2 313.01 kg, 790.10 kg and 717.84 kg respectively, the tunnel stability conforms to the design requirements and the applicable standards, and the sectional convergence deformation is within the preset control value range. 2023 Vol. 60 (6): 68-79 [Abstract] ( 325 ) [HTML 1KB] [ PDF 4147KB] ( 553 ) 80 Phase Change Cold Storage and Cooling Technology for Tunnels WU Yuanhao1 ZHANG Guozhu2 CAO Ziming2 LI Chenglin2 LIU Xinye2 LIU Yifei2 The phase change cold storage and cooling technology for tunnels is a green, environment-friendly, ener? gy-efficient and sustainable new technology that can overcome the limitations of the conventional cooling methods for tunnels with high rock temperature, thus contributing to the accomplishment of dual carbon goals. Through a literature review, this paper systematically analyzes the current status of the research into energy tunnels, phase change cold storage material, phase change energy storage structure and the phase change plate based on tunnel lining heat exchanger energy storage and also the current situation and progress of the research into application of phase change materials in tunnels and underground works, so as to promote the application and popularization of the new phase change cold storage and cooling technology for tunnels. The study indicates: (1) Energy tunnel is an efficient way of using shallow geothermal energy, and tunnel lining heat exchanger can extract sufficient shallow geothermal energy for the purpose of energy storage in phase change energy storage structure; (2) Solid-liquid phase change cold storage materials have been widely applied. It is recommended to use the composite solid-liquid phase change cold storage materials with high thermal conductivity, high latent heat, suitable phase change temperature and excellent stability in actual projects; (3) The approaches such as changing pipe type, adding fin structure and designing the phase change energy storage structures of various geometric forms will optimize and improve the heat transfer performance of phase change energy storage structure; (4) Storing cold in phase change plate by using tunnel lining heat exchanger is feasible, and increasing the thermal conductivity of phase change material, increasing difference between the phase change temperature and surrounding rock temperature and increasing the length of tunnel lining heat exchanger will all increase the energy efficiency of phase change plate; (5) Research into application of phase change materials in tunnel and underground engineering (e. g. refuge chamber) indicates that it is feasible to use phase change materials for tunnel cooling. 2023 Vol. 60 (6): 80-90 [Abstract] ( 383 ) [HTML 1KB] [ PDF 4583KB] ( 665 ) 91 Study on CO2 Adsorption Performance of Nitrogen-doped Mesoporous Carbon and Its Engineering Application ZHU Yujie LI Peinan LIU Yuqing ZHANG Ziyao Due to the increasing CO2 concentration in the atmosphere, it is of great importance to develop efficient CO2 adsorptions. A nitrogen-doped mesoporous carbon material has been developed by using resol as carbon source, F127 as soft template, cyanoguanidine as the nitrogen source and ethyl alcohol and water as mixed solvents.The structure and form of the material are analyzed by using the methods such as N2 adsorption/desorption, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscope, and the CO2 adsorption performance and mechanism of nitrogen-doped mesoporous carbon are intensively investigated. According to the results, the material has large surface area, highly ordered mesostructure and high nitrogen content, it exhibits excellent selectance of N2 and exhibits outstanding CO2 adsorption. Under 25 ℃ temperature, the CO2 adsorption efficiency of this material is 2.87 mmol/g. In its application in the Yangtze River Tunnel of Shanghai, this material is evenly applied to the tunnel surface. When the tunnel is open to traffic, the total CO2 adsorption is 55.88 kg per day. The result of this study comes as a feasible solution for carbon reduction of the infrastructure including urban tunnels. 2023 Vol. 60 (6): 91-99 [Abstract] ( 379 ) [HTML 1KB] [ PDF 5304KB] ( 692 ) 100 Study on and Outlook of Highway Tunnel Fire Warning, Smoke Control and Safe Evacuation WEI Xinjiang1,2 LI Shuai1 DU Shiming3 ZHAO Jun4 XIA Lifeng3 HAN Tongchun1 Given the characteristics of highway tunnels such as long structure, closed space and complex internal traffic environment, fire in such tunnels can easily spread and generate hot toxic fire and smoke, thus imposing severe threat to the life safety and properties of trapped personnel. This paper gives an account of the current research efforts in the areas including fire detection, fire development, fire and smoke control and safe evacuation of personnel in case of tunnel fire. Such research includes optimization and upgrading of fire detection system, determination of the key parameters such as demarcation point between far field and near field of tunnel fire smoke, length of the fire smoke backflow layer and thickness of smoke layer, the factors that affect safe evacuation of personnel in case of tunnel fire and the methods for improving safe evacuation efficiency. It is recommended to intensively investigate integrated fire video image detection (VID) technology, upgrade the intelligent ventilation control system, and use the VR training system to enhance the emergency response capability of tunnel management personnel and increase the safe evacuation efficiency during tunnel fire. 2023 Vol. 60 (6): 100-110 [Abstract] ( 376 ) [HTML 1KB] [ PDF 4039KB] ( 562 ) 111 Analysis of Horizontal Displacement of Single Pile Induced by Lateral Penetration of Tunnel Based on the Pasternak Shear Layer Theory LI Kejin1,4 QI Yuejun2 WANG You3 QIU Hui1 ZHANG Xi1 WU Guangxing2 Tunnel construction in soft soil stratum will induce noticeable surface subsidence and cause deformation of the buildings and their foundations near the tunnel. However, the deformation pattern of pile foundation of adjacent building induced by subway tunnel construction is not fully understood. With the help of the Pasternak shear layer foundation model, the mechanism by which tunnel construction in soft soil stratum affects piles has been analyzed,the calculation model has been created that is used to calculate additional horizontal displacement and additional internal force of pile and the solving method is also provided. According to the results, the model has excellent accuracy in the case of lateral penetration of tunnel by single pile; According to the parameters analysis, the effect of tunnel buried depth on adjacent single pile is mainly seen in displacement distribution, but it does not significantly affect the peak value of displacement. The thickness of elastic layer is in negative correlation with the peak values of horizontal displacement and internal force, but it will not affect the distribution pattern of displacement and internal force. For the thickness C of elastic layer, the bending moment is constant at 2 m above and below the tunnel axis,and the shear force is constant at 4 m above the tunnel axis. 2023 Vol. 60 (6): 111-119 [Abstract] ( 352 ) [HTML 1KB] [ PDF 4645KB] ( 502 ) 120 Analysis Method for Deformation of Existing Tunnel Induced by Tunnel Anchor Excavation and Support ZHOU Jie1 XI Jinzhou1 LI Haiqing1 YU Li2 TANG Langzhou2 In order to assess how tunnel anchor excavation and support will impact the safety of the existing tunnel below, the calculation model for deformation of existing tunnel induced by tunnel anchor excavation and support has been created for the first time by using the theory of beam on elastic foundation, the method for calculating the additional load under the effect of tunnel anchor excavation and support has been devised based on the Mindlin formula,and it is established that the control standard for deformation safety of existing tunnel is 12 mm. By taking the Ningqiao Tunnel-tunnel anchor system of the Yanjiang Expressway in Sichuan as an example, the deformation characteristics of existing tunnel under the effect of tunnel anchor excavation and support have been analyzed. According to the study, the existing tunnel has convex shaped deformation, the maximum deformation happens right below the anchor plug, and the tunnel deformation gradually decreases as the distance of anchor plug increases until the convergence point. The deformation of existing tunnel increases as the surrounding rock grade decreases and the distance between tunnel and tunnel anchor decreases. With Classes Ⅲ and Ⅳ surrounding rocks, the tunnel is generally in safe state.With Class Ⅴ surrounding rock, the tunnel deformation exceeds the control value during tunnel anchor excavation, so certain engineering measures are required, such as surrounding rock reinforcement and structure strengthening. 2023 Vol. 60 (6): 120-129 [Abstract] ( 328 ) [HTML 1KB] [ PDF 4471KB] ( 610 ) 130 Study on the Impact of the Number of Cracks on Tunnel Lining Stability HU Taotao HU Xiong JIA Ke In order to investigate the mechanism by which the number of cracks affects the load-bearing perfor? mance and safety of tunnel lining structure, the cracked lining internal force calculation model has been created based on the theory of fracture mechanics, the stress intensity factor calculation formula for the double-crack scenario has been deduced, and the variation pattern of the internal force and stability factor of cracked lining structure, the way the number of cracks affects the internal force of lining structure and the variation of tensile stress at the crack have been analyzed. The results indicate: compared with the crown with 1 crack, the bearing capacity is reduced by only 1.35% and stability factor reduced by 6.9% when there are 2 cracks; the bearing capacity is reduced by 2.26% and stability factor reduced by 8.1% when there are 3 cracks. Where there are multiple adjacent cracks at the crown, one crack can, to certain extent, close the other cracks and will not accelerate crack propagation. 2023 Vol. 60 (6): 130-138 [Abstract] ( 340 ) [HTML 1KB] [ PDF 4487KB] ( 578 ) 139 Tunnel Portal Section Crown Settlement SVR Prediction Models Based on Different Optimization Algorithms and Their Comparative Evaluation ZHANG Shichao1,2 WANG Yaqiong1,2 GAO Qidong1,2 ZHOU Haixiao1,2 WANG Zhifeng1,2 REN Rui1,2 Precise prediction of settlement and deformation at tunnel portal section is a priority in ensuring safe en? try into tunnel, and it is of great importance to solve the problem of high dimensionality of input layer and accurately describe the performance of machine learning prediction model. Therefore, the principal component analysis (PCA),optimization algorithm and support vector regressor (SVR) are combined to generate 6 combination prediction models based on PCA, optimization algorithm and SVR. First, the main factors that affect crown settlement are identified by using PCA. Next, the optimization algorithms including genetic algorithm (GA), particle swarm optimization (PSO) and grey wolf optimizer (GWO) are used to optimize the penalty factors and kernel parameters of SVR. At last, the combination prediction model is applied to the Shibitou Tunnel in Wenzhou, the comparative evaluation of the performance of the prediction model is conducted by using the correlation coefficient (R), root mean square error(RMSE) and mean absolute error (MAE), and the model query table is generated. The results indicate: the combination prediction models have high precision, with R≥0.987 0, RMSE≤6.792 4 mm and MAE≤3.493 7 mm. After dimensionality reduction by PCA, the GA optimization allows SVR prediction model to increase its prediction efficiency by 65%, while PSO and GWO optimization allows SVR prediction model to decrease the dimensionality of its input layer but increase its k value, which reduces the prediction efficiency, particularly so in the case of PCA-GWO-SVR. PCA-PSO-SVR prediction model has a better robustness. 2023 Vol. 60 (6): 139-150 [Abstract] ( 392 ) [HTML 1KB] [ PDF 6598KB] ( 592 ) 151 Study on the Prediction Model of Surrounding Rock Deformation in Soft Rock Tunnel Based on Multivariate Algorithm Fusion and Its Application HOU Shoujiang Since the traditional methods for predicting surrounding rock deformation in soft rock tunnels are lacking in suitability and generalization, a multivariate algorithm fusion model based on the improved D-S evidence theory has been proposed, and the process framework for prediction of surrounding rock deformation in soft rock tunnel has been established by using the Tianqiaoshan Tunnel Project as an engineering example. First, the fruit fly optimization algorithm (FOA) is used to optimize the random forest (RF) model and the whale optimization algorithm (WOA) is used to optimize the long short-term memory neural network (LSTM) model. The partial least squares regression(PLSR) prediction model and the improved D-S evidence theory are used to calculate the fusion weight of the 3 models and realize decision-level fusion, which generates the surrounding rock crown settlement and horizontal convergence prediction model based on the multivariate algorithm fusion. Then the data from the measuring points G, S1,S2 and S3 of the DK110+600 cross section of Tianqiaoshan Tunnel are used as training and test samples, to compare the prediction results of PLSR model, RF model, LSTM model, FOA-RF model, WOA-LSTM model and multivariate algorithm fusion model. At last, the multivariate algorithm fusion model is put to engineering application at the DK110+605 cross section. According to comparison of the models, the multivariate algorithm fusion model has the highest prediction accuracy, its relative error is within the range of [-1.5 mm, 1.5 mm], its average R2 value is 0.998 5 and average MAPE value 3.09%, and it allows accurate prediction of the surrounding rock deformation pat? tern of soft rock tunnel. Accounting to its engineering application, the overall prediction error of the model is within the range of [-3 mm, 2 mm], its average R2 value is 0.995 6 and average MAPE value 5.65%, and it has high enough prediction accuracy to guide construction activities. 2023 Vol. 60 (6): 151-164 [Abstract] ( 358 ) [HTML 1KB] [ PDF 11003KB] ( 491 ) 165 Optimization Method for Shield Tunnelling Parameters Based on PSO Algorithm and Its Application XIONG Yingjian1 LIU Sijin2 MA Yuyang2 FANG Yong1 HE Chuan1 In order to assist the driver in operating the shield machine and provide the operation suggestions, 5 075 101 pieces of time step data of shield tunnelling are extracted from 9 shield tunnel projects, the minimized energy consumption of shield and shortest construction duration are established as the decision-making goals, and the two tunnelling parameters including rotating speed of the cutterhead and total thrust actively operated by the shield machine driver are optimized by using the PSO algorithm, so as to provide the driver with operation suggestions based on the optimization range of various types of soil. As indicated by the comparison of the results before and after optimization in the study: (1) After optimization with the minimized energy consumption of shield being the decision-making goal,the distribution range of cutterhead rotating speed and total thrust is reduced considerably, the rank of distribution range in a descending order is sand layer, soil layer and gravel layer, and the advance rate is also increased. (2) After optimization with the shortest construction duration being the decision-making goal, the rank of cutterhead rotating speed in a descending order is soil layer, sand layer and gravel layer. The rank of total thrust and advance rate in a descending order is sand layer, soil layer and gravel layer. After the optimization, the advance rate is increased markedly and the duration is shortened. (3) The cutterhead rotating speed, total thrust and advance rate after optimization with the shortest construction duration being the decision-making goal are generally greater than the cutterhead rotating speed, total thrust and advance rate after optimization with the minimized energy consumption being the decision-making goal. Proper increase of cutterhead rotating speed and total thrust will increase the advance rate and shorten the construction duration. 2023 Vol. 60 (6): 165-174 [Abstract] ( 347 ) [HTML 1KB] [ PDF 3020KB] ( 608 ) 175 High-precision Measurement of Joint between Shield Tunnel Segments Based on SegFormer Model YANG Zhao1,2 GAO Ruchao1,2 JI Fuquan1,2 CHEN Peishuai1,2 LI Mingpeng3 In order to efficiently and precisely measure shield tunnel segment erection joint, the segment joint seg? mentation algorithm based on the SegFormer model is created, the grey space distribution information of segment joints is extracted, crude coding of image features is improved to fine coding, and the fine local features are captured while the global distribution information of segment joint is maintained, so as to enhance the robustness and accuracy of the algorithm. According to the study, the segment joint segmentation algorithm based on the SegFormer model has a measurement accuracy of 2~3 pixels. In order to widely apply the segment joint measurement algorithm, the hardware solution that combines smartphone, laser ranging and double-side supplementary lighting is proposed, so that the algorithm is deployed on a cloud server and the segment joint can be quickly measured on site by using the APP. According to comparison with manual measurement results, the photograph of segment joint shot within 5 m by a mobile phone with 10X optical zoom has physical accuracy of <0.5 mm, which is enough to meet the segment joint measurement standard. 2023 Vol. 60 (6): 175-182 [Abstract] ( 351 ) [HTML 1KB] [ PDF 2899KB] ( 689 ) 183 Study on Consumption in Shield Tunnelling under Complex Geological Conditions Based on Random Forest Algorithm PANG Long1 ZHENG Xin1 FU Shirong1 ZHOU Chuanyue2 ZHANG Jin2 In order to ascertain how the geological parameters will affect consumption of main materials in shield tunnelling under complex geological conditions, the random forest regression algorithm and random forest classification algorithm models have been created to conduct model training and prediction of the relation between consumption of grease, labor, water and electricity and synchronous grouting coefficient and the geological parameters. The results indicate: (1) Compressive strength is the most important geological characteristic parameter that affects consumption of labor, water, electricity and grease and is also the second most important parameter that affects the synchronous grouting coefficient; (2) Consumption of main materials in shield tunnelling is in positive correlation with compressive strength; (3) With compressive strength used as the single classification index, the quota classification standard for shield tunnelling under complex geological conditions has been established. As revealed by the classification statistics on consumption of main materials, the consumption of materials for tunnelling in soft soil stratum is approximate to the standard value, while the consumption of materials for tunnelling in hard rock is over 2 times the standard value; (4) For the non-real-time recorded data such as consumption of labor, water and electricity, the random forest regression algorithm will generate more accurate analysis results. For the real-time recorded data such as consumption of grease, the random forest classification algorithm will generate better prediction results. 2023 Vol. 60 (6): 183-191 [Abstract] ( 308 ) [HTML 1KB] [ PDF 4710KB] ( 659 ) 192 Study on Rock Breaking Mechanism of Undercutting Cutter at Precut Slot on Free Surface ZHANG Qin1 SU Jinhua2 LI Aijun1 XU Binbin1 YAN Xiaolei1 LIU Ding1 YANG Junqi1TANG Jintao1 LI Hongsheng3 In order to enhance the performance of undercutting cutter in breaking hard rock and reduce rock breaking load, the numerical model for hard rock breaking by undercutting cutter at precut slot has been created to investigate how various combinations of cutting thickness values and slotting parameters (slot spacing, slot depth) will affect the rock breaking performance of undercutting cutter, and the mechanism by which precut slot affects the rock breaking process of undercutting cutter has been revealed. As the study results indicate, when the slot spacing is equal to the cutter diameter, the rock with precut slot can be equivalent to a rock with unconfined compression, and the cutting force is reduced by over 30% as compared with cutting an unslotted rock. Besides, the matching relation between cutting thickness of undercutting cutter and slot spacing will significantly affect the specific energy of rock breaking. To achieve the optimum specific energy of rock breaking, the cutting depth and slot spacing are 20 mm and 100 mm respectively. In addition, the relation between fractal dimension of rock debris and specific energy of rock breaking has been established, i.e. the specific energy consumption increases linearly as the fractal dimension increases 2023 Vol. 60 (6): 192-198 [Abstract] ( 324 ) [HTML 1KB] [ PDF 5125KB] ( 521 ) 199 Analysis of Long-term Stability of Mudstone Tunnel Invert—Case Study of a Tunnel in Daban Geological Zone in Xinjiang SI Ninghu1 ZHAO Chunpeng2 CHANG Zhou1 YAN Changgen1 LAI Hongpeng1 LU Zhifang3 XIE Wanye1 By taking a tunnel in the Daban geological zone in Xinjiang for example, the long-term stability of mud? stone tunnel invert has been analyzed. After analysis of the tunnel rock mass structure, rock strength and long-term deformation monitoring data, the mechanical parameters and creep parameters of the monitored tunnel rock mass have been obtained by using the H-B strength criterion and BP neural network algorithm. By using the CPOWER model built in the FLAC 3D software, the numerical simulation model for typical section has been created, so as to analyze how various lining support strengths and invert radius of curvature will affect the stability of tunnel invert under the rheological effect of mudstone in the operation period. The results indicate: with mudstone rheology taken into account, the main deformation of tunnel is the heave at the center of invert. First increase of support strength or decrease of invert radius of curvature will significantly improve the stress state of tunnel structure, inhibit surrounding rock deformation and reinforce the stability of surrounding rock. However, as the support strength continues increasing or the invert radius of curvature continues decreasing, this inhibiting effect gradually becomes weaker. When the support is changed from I16 I-beam to two-layer arch frame, the center of invert still has 11.14 mm heave. When the invert radius of curvature is reduced from 16 m to 14 m, the heave at the center of invert is reduced from 33.7 mm to 3.37 mm, and the eventual displacement meets the requirements for later stage of tunnel operation. Compared with increasing the support strength, reducing the invert radius of curvature will fundamentally inhibit the heave at the center of invert, and also allow more even stress on surrounding rock and support structure. When the invert radius of curvature is properly reduced in the construction stage, the tunnel is in a relatively balanced state, and the rheological effect does not significantly affect the stress state of the tunnel. of curvature 210 2023 Vol. 60 (6): 199-210 [Abstract] ( 337 ) [HTML 1KB] [ PDF 5460KB] ( 591 ) 211 Study on Effectiveness and Suitability of Thermal Insulation Layer of Different Tunnel Drainage System Structures in Cold Reg WANG Zhijie1,2 XIE Shenghao1,2 ZHOU Feicong1,2 WANG Lei3 MA Zhifu4 YANG Changxian4 By using the Xianfeng Tunnel of Harbin-Mudanjiang High-speed Railway as an example, this paper is meant to investigate the tunnel temperature field under the combined effect of the variables such as in-tunnel ambient temperature and tunnel surrounding rock temperature after installation of thermal insulation layer. Based on the specific surrounding rock initial temperature and in-tunnel temperature, an appropriate drainage system structure is recommended for the tunnel in cold region, to ensure safety and stability of the drainage system. Under the same condition, according to this study, the temperature values at the measuring points of the drainage system have increased to various extents after thermal insulation layer is installed. Installation of thermal insulation layer will render excellent thermal insulation effect on the water pipe behind the lining, but have limited thermal insulation effect on the side ditch and vertical water pipe. The main difference in drainage system structure is indicated by the temperature in the center (deep) ditch. Depending on the in-tunnel ambient temperature and tunnel surrounding rock temperature, the drainage system structure of tunnel in cold region can be divided into three zones, including Zone A (without thermal insulation), Zone B (center ditch-thermal insulation) and Zone C (center deep ditch-thermal insulation). 2023 Vol. 60 (6): 211-219 [Abstract] ( 316 ) [HTML 1KB] [ PDF 6670KB] ( 668 ) 220 Optimization of the Design and Construction Scheme of Tunnel Entry and Conver? sion System for Removal of Anti-slide Pile in Architecturally Sensitive Area YANG Chunshan1 YANG Xueqiang2 WANG Yatian2 LIN Yonggui1 A tunnel excavation scheme analysis is conducted by using the Yangguang Tunnel in Panzhihua, and the conversion system is proposed based on the stressing characteristics of surrounding rock and structure during removal of anti-slide pile. The fine calculation model for tunnel excavation process has been created, the deformation response characteristics of surrounding rock, tunnel and building corresponding to different construction methods have been investigated, the study on scheme optimization has been conducted by taking into account the indicators including safety, economic efficiency, feasibility and duration, and field test and demonstration have been completed.The results indicate: under the effect of the conversion system in "counterfort retaining wall + anti-slide pile" composite structure, the surrounding rock-structure displacement is effectively inhibited and overall stability is maintained; compared with CRD method, reserved core method will generate more obvious mechanical disturbance, with maximally 40% difference between the two, but both construction methods meet the requirements for the displacement of stratum, conversion structure and building; during excavation for removal of anti-slide pile in tunnel, the stratum mainly experiences vertical displacement, the conversion system shows the most obvious response right at the pile cutting position, and the existing building is slightly inclined towards the tunnel side; in the original construction construction method, the CRD method generates less mechanical disturbance, but comes with high engineering cost, high technical difficulty, complex process and long duration. After a comprehensive comparison, the reserved core method is selected. According to field survey, the selected scheme is rational and brings desirable construction results in the project. 2023 Vol. 60 (6): 220-227 [Abstract] ( 375 ) [HTML 1KB] [ PDF 5883KB] ( 653 ) 228 Confining Pressure Effect of Dynamic Failure of Limestone under Cyclic Impact ZHOU Zeqing1 WANG Jianguo1 JIANG Xinwen2 ZHANG Piyun2 ZHOU Qinglian1 In order to optimize the blasting parameters for underground tunnelling in surrounding rock and control the disturbance of surrounding rock caused by blasting, it is sorely necessary to identify the dynamic mechanical properties, failure characteristics and energy consumption of surrounding rock. By using the Split Hopkinson Pressure Bar (SHPB), the experimental study has been conducted under three-dimensional dynamic and static combined cyclic impact, so as to analyze how certain axial pressure, various confining pressures and cyclic impact coupling effect will affect the peak stress, dynamic compressive strength, failure characteristics and energy absorption rate of limestone. According to the results, under the given axial pressure and with the same number of impacts, the peak stress and dynamic compressive strength of limestone will increase and then decrease as the confining pressure increases,and the failure degree will decrease and then increase as the confining pressure increases. This indicates that proper increase of confining pressure will enhance the impact resistance of limestone. However, such enhancement is not unlimited, because excessively high confining pressure will induce internal damage and degradation of limestone and consequently impair its impact resistance. The energy absorption rate of limestone is in a polynomial relation with the number of impacts. The impact incident energy absorbed by limestone will decrease and then increase as the confining pressure increases. Properly applied confining pressure will decrease the energy absorption of limestone, but excessively high confining pressure will cause the energy absorption of limestone specimen to increase markedly. Therefore, before blasting and excavation in underground engineering, the stress state of surrounding rock can be determined through surrounding rock stress measurement and thus the rock breaking effectiveness of specific explosive quantity in a sound can be predicted. This will afford the theoretical support for adjusting and optimizing the blasting parameters and controlling the damage and disturbance of surrounding rock caused by blasting. 2023 Vol. 60 (6): 228-236 [Abstract] ( 332 ) [HTML 1KB] [ PDF 5377KB] ( 479 ) 237 Experimental Study on Rheological Properties of Slurry in Slurry Shield Tunnelling Crossing Sea WANG Chengzhen1 DING Wantao2,3 YU Wenrui1 WANG Zhicheng1 SUN Tengyun1 WANG Zhongrong2 Given the fact that the rheological properties of seawater slurry under the effect of various factors and the rheological equation are still unknown, a set of laboratory rheological tests have been conducted by using two typical viscosifiers, in order to investigate how different contents of viscosifier and ambient temperatures will affect the rheological parameters of seawater slurry and reveal the rheological parameters development mechanism of slurry from the microscopic aspect. The results indicate: compared with sodium carboxymethyl cellulose (CMC), the viscosifier polyanionic cellulose (PAC) of the same content will bring better result of improving the fluidity of seawater slurry,significantly improve the viscosity and physical stability of slurry, and the viscosity of seawater slurry with 0.4%PAC and 12% sodium bentonite is increased by a large margin. With different contents of PAC, the flow pattern of seawater slurry always matches the power law model, and the consistency coefficient k and rheological index n decrease and increase respectively as temperature increases. In the microscopic aspect, the interaction between the oxhydryl on the molecular chain of viscosifier and the bentonite particle creates the intramolecular hydrogen bond, which is the main factor that allows the viscosifier to increase the fluidity of slurry. 2023 Vol. 60 (6): 237-245 [Abstract] ( 331 ) [HTML 1KB] [ PDF 5990KB] ( 539 ) 246 Study on the Ambient Temperature Control Technology for Construction of a Tunnel Near Heat-conducting Fault and with High Rock Temperature CUI Guangyao1 WEI Yifei1 XIONG Yong1 WANG Daoyuan2,3 TIAN Xiaolu4 In order to investigate the ambient temperature control technology for construction of a tunnel near heatconducting fault and with high rock temperature, the cooling effectiveness of the solutions including mechanical ventilation + ice, mechanical ventilation + mist spray and mechanical ventilation + ice + mist spray has been studied under different mechanical ventilation rates by using a tunnel project with high rock temperature as the study case.The results indicate: greater mechanical ventilation rate enables faster cooling rate and greater temperature drop;when mechanical ventilation rate is increased to a certain level, the tunnel cooling effectiveness is no longer improved notably, and other auxiliary measures are needed to further reduce temperature; in cooling by ice, consumption of more ice will bring faster cooling rate and better cooling effectiveness; in the mechanical ventilation + ice +mist spray solution, the average cooling rate is 5.37 °C/min, temperature drop is 53.74 °C and the stable ambient temperature is 26.26 °C, so this solution is the most effective solution for ambient temperature control in tunnel construction; when this temperature control solution is applied on site, the rock temperature at tunnel face is reduced to 46.1°C and the ambient temperature in tunnel is 25~27 °C, which meets the applicable standard. 2023 Vol. 60 (6): 246-254 [Abstract] ( 314 ) [HTML 1KB] [ PDF 4652KB] ( 529 ) 255 Study on Backfill Grouting Behind the Segment of Double Shield TBM Metro Tunnel Crossing Water-bearing Fault Zone LIU Quanwei1,2 YANG Xing3 YE Shoujie1,2 JIANG Yusheng3 ZHAO Jizeng1,2 TAN Zhuolin4 YANG Zhiyong3 For tunnelling through a stratum in water-bearing fault zone by double shield TBM in urban metro construction, the problems such as water inflow and poor self-stability of surrounding rock are very likely to occur.Grouting in the gap between the segment wall and surrounding rock will prevent water inflow, and also reinforce and support the surrounding rock in a timely manner. On this basis, the TBM shield tail blocking plate structure is designed, and a new construction process is devised that allows pea gravel backfilling and synchronous grouting. First,the optimum mix ratio of synchronous grouting slurry is determined through laboratory test. Then based on the positions of the preformed holes of segment and the volume of gap between surrounding rock and segment, the construction process of "three-step pea gravel backfilling" and "three-step grouting" is devised. At last, the process is put to field application. The results indicate: the optimum solution A mix ratio of synchronous grouting slurry is fly ash∶cement∶ water=2.5∶1∶2, the concretion rate is up to 95%, and the double-solution grout with solution A∶solution B=1∶1 has the shortest initial setting time and strongest resistance against water dilution. When this process is applied in practical work, pea gravel backfilling creates solid mass, the backfilled structure is intact, the formed tunnel structure is stable, segment settlement is effectively controlled, and there is no water leakage. 2023 Vol. 60 (6): 255-261 [Abstract] ( 389 ) [HTML 1KB] [ PDF 3320KB] ( 624 ) 262 Experimental Study on the Improvement of Gasket Gas Tightness at Segment Joints in Shield Tunnels XIAO Mingqing1 ZHONG Yuanyuan2 CHEN Peng3 WANG Jun4 QI Zhaochen5 ZHANG Weibin6 The gasket contact surface gas leakage model has been built based on the Roth model, in order to investi? gate the correlation between the segment gasket surface roughness and segment joint gas tightness in shield tunnels.The surface roughness of forming die for elastic gasket of segment is improved by nitriding, laser strengthening and ultrasonic polishing, so as to improve the surface quality of the formed gasket, and the result is demonstrated through testing. The study indicates: the gas leak rate can be used as an indicator for assessing the gas tightness of gasket; the coefficient of friction of polished gasket is 7%~9% less than that of unpolished gasket, while decrease of coefficient of friction will effectively reduce the deformation of gasket during assembly. The gas tightness of the gasket formed by polished die is 10% better than that of the gasket formed by unpolished die. 2023 Vol. 60 (6): 262-268 [Abstract] ( 391 ) [HTML 1KB] [ PDF 3373KB] ( 566 ) 269 Study on the Rheological Properties of Calcium Oxide-Sodium Carbonate Composite Activated Slag Based Grouting Material CHEN Xin1,2,3 YIN Suxin2 The prerequisite of building the theoretical model of grout diffusion is to determine the flow pattern of grout and time varying pattern of rheological parameters. In order to investigate the rheological properties of calcium oxide-sodium carbonate composite activated slag based grouting material, the new grouting material whose bleeding rate and concretion compressive strength are superior to those of the Grade 42.5 ordinary Portland cement is prepared by using calcium oxide and sodium carbonate (amount of substance ratio is 1∶1) as activators. Next, the rheological properties of the grouting materials with different water-cement ratios and hydration times are tested by using the rotary viscometer. Based on the test results, it is feasible to examine how the water-cement ratio and hydration time will affect the flow pattern and rheological parameters of grouting material. According to the results, water-cement ratio will significantly affect the rheological pattern of calcium oxide-sodium carbonate composite activated slag based grouting material. The grouting materials with water-cement ratio of 0.60~1.00 do not have a single flow pattern, but are classified as Bingham fluid and Newtonian fluid. The plastic viscosity and yield stress will decrease as the water-cement ratio increases, with the two being in a power functional relation. Similar to cement-based grouting material, calcium oxide-sodium carbonate composite activated slag based grouting material will maintain its flow pattern in the grouting process, while only the rheological parameter changes with the hydration time. The greater the water-cement ratio of grouting material, the less the hydration time will affect the relation between shear stress and shear rate and the value of rheological parameter. Unlike cement-based grouting material, the variation pattern of plastic viscosity of the new grouting material resulting from change of hydration time is represented by a power function instead of exponential function. The yield stress of the grout with water-cement ratio of 0.60 and0.65 will increase linearly as the hydration time increases, while hydration time does not significantly affect the yield stress of the grout with water-cement ratio of 0.70 and 0.75, i.e. the yield stress is not time-varying. The viscosity of Newtonian grout with water-cement ratio of 0.80, 0.90 and 1.00 changes slightly as the hydration time increases, but only slightly, so it is deemed that its viscosity is not time-varying. 2023 Vol. 60 (6): 269-277 [Abstract] ( 354 ) [HTML 1KB] [ PDF 4675KB] ( 601 )

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