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Deformation mechanism and collapse treatment of the rock surrounding a shallow tunnel based on on-site monitoring

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Journal of Mountain Science 2020年第12期17卷 2897-2914页

作者： QIU Hong-zhi CHEN Xiao-qing WU Qi-hong WANG Ren-chao ZHAO Wan-yu QIAN Ke-jiang School of Architecture and Civil Engineering Chengdu UniversityChengdu 610106China Key Laboratory of Mountain Hazards and Earth Surface Processes Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China Hunan International Scientific and Technological Innovation Cooperation Base of Advanced Construction and Maintenance Technology of Highway Changsha University of Science&TechnologyChangsha 410114China School of Computer Science and Engineering University of Electronic Science and Technology of ChinaChengdu 611731China

When tunnels are constructed at shallow depths in areas with poor geological conditions,such as portal sections,valleys and hillsides in regions with granitic bedrock,considerable excavation-induced deformation of the surrounding rock may occur,potentially resulting in tunnel *** main reason for these problems is the lack of understanding of the deformation mechanism and evolution of the soft granitic rock surrounding the tunnel and the adoption of inappropriate construction technology and *** article analyzes the deformation mechanism of the rock surrounding a shallow tunnel based on in situ monitoring data as a case study and suggests that certain measures should be taken to effectively control the deformation of the surrounding rock and to minimize the potential for tunnel *** results show that the deformation of the granitic soil surrounding the tunnel can be divided into three stages:the rapid deformation stage,the slow deformation stage and the stabilization *** construction methods should be carefully selected to ensure safety during tunnel excavation in the first *** avoid secondary disasters caused by tunnel collapses,three treatment measures may be implemented as part of safety management:enhancing the monitoring of the surrounding rock deformation,adjusting the construction methods and optimizing the support *** particular,accurate monitoring data and timely information feedback play a vital role in tunnel ***,engineers with considerable engineering experience and professional knowledge are needed to analyze the monitoring data and make accurate predictions of tunnel deformation to ensure that reasonable measures are taken in the process of shallow tunnel excavation.

关键词： shallow tunnel Surrounding rock deformation Field monitoring Treatment for collapse Information feedback

Numerical analysis and field monitoring tests on shallow tunnels under weak surrounding rock

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Journal of Central South University 2015年第10期22卷 4056-4063页

作者：刘建华刘晓明张永杰肖庭 School of Traffic and Transportation Engineering Changsha University of Science and Technology College of Civil Engineering Hunan University School of Civil Engineering and Architecture Changsha University of Science and Technology

The Jianpudong No. 4 tunnel is a shallow tunnel, which belongs to Shaoshan County scenic highway in Hunan province, China and whose surrounding rock is weak. According to its characteristics, the field monitoring tests and numerical analysis were done. The mechanical characteristics of shallow tunnels under weak surrounding rock and the stress-strain rule of surrounding rock and support were analyzed. The numerical analysis results show that the settlement caused by upper bench excavating accounts for 44% of the total settlement, and the settlement caused by tunnel upper bench supporting accounts for 56% of the total settlement. The maximum axial force of shotcrete lining is 177.2 k N, which locates in hance under the secondary lining. The maximum moment of shotcrete lining is 5.08 k N·m, which locates in the arch foot. The stress curve of steel arch has three obvious stages during the tunnel construction. The maximum axial force of steel arch is 297.4 k N, which locates in tunnel vault. The axial forces of steel arch are respectively 23.5 k N and-21.8 k N, which is influenced by eccentric compression of shallow tunnel and locates in hance. The results show that there is larger earth pressure in tunnel vault which is most unfavorable position of steel arch. Therefore, the advance support should be strengthened in tunnel vault during construction process.

关键词： tunnel engineering shallow tunnel weak surrounding rock numerical analysis field monitoring tests

Upper bound solutions for supporting pressures of shallow tunnels with nonlinear failure criterion

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Journal of Central South University 2013年第7期20卷 2034-2040页

作者： YANG Xiao-li ZHANG Dao-bing WANG Zuo-wei School of Civil Engineering Central South University Changsha 410075 China

Linear failure criterion is widely used in calculation of earth pressure acting on shallow tunnels. However, experimental evidence shows that nonlinear failure criterion is able to represent fairly well the failure of almost all types of rocks, A nonlinear Hock-Brown failure criterion is employed to estimate the supporting pressures of shallow tunnels in limit analysis framework. Two failure mechanisms are proposed for calculating the work rate of extemal force and the internal energy dissipation. A tangential line to the nonlinear failure criterion is used to formulate the supporting pressure problem as a nonlinear programming problem. The objective function formulated in this way is minimized with respect to the failure mechanism and the location of tangency point. In order to assess the validity, the supporting pressures for the proposed failure mechanisms are calculated and compared with each other, and the present results are compared with previously published solutions when the nonlinear criterion is reduced to linear criterion. The agreement supports the validity of the proposed failure mechanisms. An experiment is conducted to investigate the influences of the nonlinear criterion on collapse shape and supporting pressures of shallow tunnels.

关键词： shallow tunnel nonlinear criterion limit analysis supporting pressure failure mechanism

Upper bound solutions of stability factor of shallow tunnels in saturated soil based on strength reduction technique

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Journal of Central South University 2012年第7期19卷 2008-2015页

作者：黄阜张道兵孙志彬金启云 School of Civil Engineering and Architecture Changsha University of Science and Technology School of Civil Engineering Central South University

Based on the upper bound theorem of limit analysis,the factor of safety for shallow tunnel in saturated soil is calculated in conjunction with the strength reduction *** analyze the influence of the pore pressure on the factor of safety for shallow tunnel,the power of pore pressure is regarded as a power of external force in the energy *** the rigid multiple-block failure mechanism,the objective function for the factor of safety is constructed and the optimal solutions are derived by employing the sequential quadratic *** to the results of optimization calculation,the factor of safety of shallow tunnel for different pore pressure coefficients and variational groundwater tables are *** parameter analysis shows that the pore pressure coefficient and the location of the groundwater table have significant influence on the factor of safety for shallow tunnel.

关键词： strength reduction technique upper bound theorem pore pressure shallow tunnel factor of safety

Calculation of maximum surface settlement induced by EPB shield tunnelling and introducing most effective parameter

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Journal of Central South University 2016年第12期23卷 3273-3283页

作者： Sayed Rahim Moeinossadat Kaveh Ahangari Kourosh Shahriar Department of Mining Engineering Science and Research Branch Islamic Azad University Tehran Iran Department of Mining and Metallurgical Engineering Amirkabir University of Technology Tehran Iran

This study aims to predict ground surface settlement due to shallow tunneling and introduce the most affecting parameters on this *** on data collected from Shanghai LRT Line 2 project undertaken by TBM-EPB method,this research has considered the tunnel's geometric,strength,and operational factors as the dependent *** first,multiple regression(MR) method was used to propose equations based on various *** results indicated the dependency of surface settlement on many parameters so that the interactions among different parameters make it impossible to use MR method as it leads to equations of poor *** such,adaptive neuro-fuzzy inference system(ANFIS),was used to evaluate its capabilities in terms of predicting surface *** generated ANFIS models,the model with all input parameters considered produced the best prediction,so as its associated R^2 in the test phase was obtained to be *** equations and models in which operational factors were taken into consideration gave better prediction results indicating larger relative effect of such *** sensitivity analysis of ANFIS model,cosine amplitude method(CAM) was employed; among other dependent variables,fill factor of grouting(n) and grouting pressure(P) were identified as the most affecting parameters.

关键词： surface settlement shallow tunnel tunnel boring machine (TBM) multiple regression (MR) adaptive neuro-fuzzyinference system (ANFIS) cosine amplitude method (CAM)

Influences of stress dilation on shape of failure surface for shallow tunnels

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Influences of stress dilation on shape of failure surface fo...