Currently,model tests are increasingly being used to simulate the construction of mountain tunnels,but the support structure of the model tests does not show the composite lining,and the force laws of the composite li...Currently,model tests are increasingly being used to simulate the construction of mountain tunnels,but the support structure of the model tests does not show the composite lining,and the force laws of the composite lining are not yet clear.In this research,the force variation of composite lining under three cases in model tests of deep-buried tunnels were carried out with the surrounding rock grade and installation time as the variation factors.The test results reveal that:(1)The suitable method to reduce the contact load between the secondary lining and primary support is to enhance the primary support in the soft and weak surrounding rock.Correspondingly,for ClassⅢsurrounding rock and better quality of surrounding rock,the primary support can lag behind the excavation face a certain distance.(2)The axial forces of the bolts tend to rise with concentration of 0.4 kN-0.7 kN after the secondary lining was installed.(3)With or without two to three excavation cycles delayed,the load sharing ratio of the secondary lining of the Class III surrounding rock is less than 10%.Finally,the numerical simulation verifies the feasibility of the model tests.展开更多
A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnel...A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnels,while some sections close to the faults completely collapsed.A summary of qualitative data collected from reports and papers is presented regarding the behavior of the 55 mountain tunnels near the epicenter during the earthquake.Based on the seismic investigation and data collection of mountain tunnels,the tunnel damage is classified into six most common damage models involving cracking,spalling,shear failure,dislocation,pavement uplift and collapse.Detailed study and discussion are then carried out on the damage models.In order to examine the influencing factors of the damage magnitude of the mountain tunnels,the correlations between epicentral distance,earthquake intensity,overburden depth,geological condition and damage levels are analyzed.The relationships between earthquake parameters and different damagemodels are developed and discussed.Also,suggestions are provided to improve the seismic resistance of mountain tunnels.展开更多
Seismic risk evaluation(SRE) in early stages(e.g., project planning and preliminary design)for a mountain tunnel located in seismic areas has the same importance as that in final stages(e.g.,performance-based design, ...Seismic risk evaluation(SRE) in early stages(e.g., project planning and preliminary design)for a mountain tunnel located in seismic areas has the same importance as that in final stages(e.g.,performance-based design, structural analysis, and optimization). SRE for planning mountain tunnels bridges the gap between the planning on the macro level and the design/analysis on the micro level regarding the risk management of infrastructural systems. A transition from subjective or qualitative description to objective or quantitative quantification of seismic risk is aimed to improve the seismic behavior of the mountain tunnel and thus reduce the associated seismic risk. A new method of systematic SRE for the planning mountain tunnel was presented herein. The method employs extension theory(ET)and an ET-based improved analytical hierarchy process. Additionally, a new risk-classification criterion is proposed to classify and quantify the seismic risk for a planning mountain tunnel. This SRE method is applied to a mountain tunnel in southwest China, using the extension model based on matter element theory and dependent function operation.The reasonability and flexibility of the SRE method for application to the mountain tunnel are illustrated.According to different seismic risk levels and classification criteria, methods and measures for improving the seismic design are proposed, which can reduce the seismic risk and provide a frame of reference for elaborate seismic design.展开更多
Mountain tunnels in cold regions are vulnerable to adverse effects of freezing action.Thus,it is necessary to identify the lining responses of shallow mountain tunnels subjected to freezing action.To quantify the infl...Mountain tunnels in cold regions are vulnerable to adverse effects of freezing action.Thus,it is necessary to identify the lining responses of shallow mountain tunnels subjected to freezing action.To quantify the influence of freezing action and key design parameters(such as cross-sectional shape;lining thickness;and waterproof measures)on the lining response,a thermal-hydro-mechanical coupled finite element(FE)model is established and verified.Then,specific consideration is given to the lining internal force and resulting axial stresses.And the influences of the cross-sectional shape,concrete parameters,and waterproof measures on the lining responses are investigated.Generally,the rectangular tunnel has the worst security;the circular tunnel is the safest.On the other hand,when the thermal conductivity is less than 2.2[W/(m·K)],a greater thermal conductivity will cause a greater risk of damage to the lining.Moreover,the drainage plate can reduce the value of minimum axial stresses,whether frozen or not,even eliminating the tensiondamaged area.Overall,this study helps to estimate the lining responses and prevent frost damages for shallow mountain tunnels during freezing period.展开更多
Large amount of groundwater discharging from tunnel is likely to cause destruction of the ecological environment in the vicinity of the tunnel, thus an appropriate drainage criterion should be established to balance t...Large amount of groundwater discharging from tunnel is likely to cause destruction of the ecological environment in the vicinity of the tunnel, thus an appropriate drainage criterion should be established to balance the tunnel construction and groundwater.To assess the related problems, an limiting drainage standard ranging from 0.5 to 2.0 m3/(m·d) was suggested for mountain tunnels based on survey and comparative analysis. After that, for the purpose of verifying the rationality of the standard, a calculated formula for dewatering funnel volume caused by drainage was deduced on the basis of the groundwater dynamics and experience method.Furthermore, the equation about the relationship between water discharge and drawdown of groundwater table was presented. The permeability coefficient, specific yield and groundwater table value were introduced, and then combined with the above equation, the drawdown of groundwater table under the proposed limiting drainage criterion was calculated. It is shown that the proposed drainage standard can reach the purpose of protecting ecological environment under the following two conditions. One is the permeability coefficient ranges from 10-4 to 10-5 m/s and the specific yield ranges from 0.1 to 0.001. The other is the permeability coefficient varies from 10-6 to 10-8 m/s and the specific yield varies from 0.1 to 0.01. In addition, a majority of common geotechnical layers are involved in the above ranges. Thus, the proposed limiting drainage standard which ranges from 0.5 to 2.0 m3/(m·d) for mountain tunnel is reasonable.展开更多
On May 12, 2008, a strong earthquake with a magnitude of 8.0 (Ms) struck Wenchuan town, in the eastern Sichuan area of west China. Following the earthquake on May 18, the Southwest Jiaotong University organized a dama...On May 12, 2008, a strong earthquake with a magnitude of 8.0 (Ms) struck Wenchuan town, in the eastern Sichuan area of west China. Following the earthquake on May 18, the Southwest Jiaotong University organized a damage survey team and dispatched it to the affected area for the investigation into the damage and collection of information and data. This paper outlines the findings of this investigation on the earthquake disaster to mountain tunnels and geotechnical engineering. The systematic investigation, involving geological conditions, design documents, construction and maintenance records of the tunnels, has been conducted and the degree of damage to investigated tunnels has been assessed according to the width and length of cracks, the stability of the slope above the tunnel, and the condition of the groundwater inrush. The results show that the major damage of the mountain tunnels was mainly concentrated in the tunnel portals due to widespread landslides and rockfalls, and the inner part of investigated tunnels suffered moderate damages mainly due to fault displacements. It is hoped that the information shared herein could enhance the outstanding of seismic behavior of mountain tunnels and improve seismic design and construction procedures.展开更多
为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指...为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指标体系;其次,采用云模型将定性指标定量描述,并运用CRITIC(criteria importance though intercriteria correlation)确定指标权重;最后以灰色关联差异信息值为基础,结合欧几里得理论计算修正的加权靶心距,通过对比靶心距实现方案优选,并采用单因素轮换法(one-at-a-time,OAT)进行了指标敏感性分析。结果表明:最优方案的加权靶心距为0.610,评选出的方案与实际一致,并分析出“地形地貌改变”为对方案评选影响最大的指标。可见,该方法呈现了各方案的优劣,使山区隧道施工场地布置方案评选更科学、合理。展开更多
基金the Scientific Research Project of Zhejiang Provincial Transportation Department(2021050)for the preparation of this manuscript。
文摘Currently,model tests are increasingly being used to simulate the construction of mountain tunnels,but the support structure of the model tests does not show the composite lining,and the force laws of the composite lining are not yet clear.In this research,the force variation of composite lining under three cases in model tests of deep-buried tunnels were carried out with the surrounding rock grade and installation time as the variation factors.The test results reveal that:(1)The suitable method to reduce the contact load between the secondary lining and primary support is to enhance the primary support in the soft and weak surrounding rock.Correspondingly,for ClassⅢsurrounding rock and better quality of surrounding rock,the primary support can lag behind the excavation face a certain distance.(2)The axial forces of the bolts tend to rise with concentration of 0.4 kN-0.7 kN after the secondary lining was installed.(3)With or without two to three excavation cycles delayed,the load sharing ratio of the secondary lining of the Class III surrounding rock is less than 10%.Finally,the numerical simulation verifies the feasibility of the model tests.
基金supported by the National Natural Science Foundation of China (51678438 & 51308574 & 51478343 & 41672289)the National Basic Research Program of China (2015CB057902)+2 种基金the Shanghai Educational Development Foundation (13CG17)the Shanghai Committee of Science and Technology (13231200503 & 16DZ1200302 & 16DZ1201904)the support from the Fundamental Research Funds for the Central Universities
文摘A number of mountain tunnels suffered significant damage to various extent during the 2008 Wenchuan earthquake in China.Damage ranging from small to heavy cracking was observed both at the portal and inside the tunnels,while some sections close to the faults completely collapsed.A summary of qualitative data collected from reports and papers is presented regarding the behavior of the 55 mountain tunnels near the epicenter during the earthquake.Based on the seismic investigation and data collection of mountain tunnels,the tunnel damage is classified into six most common damage models involving cracking,spalling,shear failure,dislocation,pavement uplift and collapse.Detailed study and discussion are then carried out on the damage models.In order to examine the influencing factors of the damage magnitude of the mountain tunnels,the correlations between epicentral distance,earthquake intensity,overburden depth,geological condition and damage levels are analyzed.The relationships between earthquake parameters and different damagemodels are developed and discussed.Also,suggestions are provided to improve the seismic resistance of mountain tunnels.
基金financially supported by the National Key Research and Development Program of China (2016YFB1200401)the Western Construction Project of the Ministry of Transport (Grant No. 2015318J29040)
文摘Seismic risk evaluation(SRE) in early stages(e.g., project planning and preliminary design)for a mountain tunnel located in seismic areas has the same importance as that in final stages(e.g.,performance-based design, structural analysis, and optimization). SRE for planning mountain tunnels bridges the gap between the planning on the macro level and the design/analysis on the micro level regarding the risk management of infrastructural systems. A transition from subjective or qualitative description to objective or quantitative quantification of seismic risk is aimed to improve the seismic behavior of the mountain tunnel and thus reduce the associated seismic risk. A new method of systematic SRE for the planning mountain tunnel was presented herein. The method employs extension theory(ET)and an ET-based improved analytical hierarchy process. Additionally, a new risk-classification criterion is proposed to classify and quantify the seismic risk for a planning mountain tunnel. This SRE method is applied to a mountain tunnel in southwest China, using the extension model based on matter element theory and dependent function operation.The reasonability and flexibility of the SRE method for application to the mountain tunnel are illustrated.According to different seismic risk levels and classification criteria, methods and measures for improving the seismic design are proposed, which can reduce the seismic risk and provide a frame of reference for elaborate seismic design.
基金supported by the National Key R&D Program of China(Grant No.2018YFC1505305)the National Major Scientific Instruments Development Project of China(Grant No.41627801)+2 种基金the State Key Program of the National Natural Science Foundation of China(Grant No.41731288 and 41772315)the Technology Research and Development Plan Program of Heilongjiang Province(Grant No.GA19A501)the Open Research Fund Program of the State Key Laboratory for Geomechanics and Deep Underground Engineering of China(Grant No.SKLGDUEK1807)。
文摘Mountain tunnels in cold regions are vulnerable to adverse effects of freezing action.Thus,it is necessary to identify the lining responses of shallow mountain tunnels subjected to freezing action.To quantify the influence of freezing action and key design parameters(such as cross-sectional shape;lining thickness;and waterproof measures)on the lining response,a thermal-hydro-mechanical coupled finite element(FE)model is established and verified.Then,specific consideration is given to the lining internal force and resulting axial stresses.And the influences of the cross-sectional shape,concrete parameters,and waterproof measures on the lining responses are investigated.Generally,the rectangular tunnel has the worst security;the circular tunnel is the safest.On the other hand,when the thermal conductivity is less than 2.2[W/(m·K)],a greater thermal conductivity will cause a greater risk of damage to the lining.Moreover,the drainage plate can reduce the value of minimum axial stresses,whether frozen or not,even eliminating the tensiondamaged area.Overall,this study helps to estimate the lining responses and prevent frost damages for shallow mountain tunnels during freezing period.
基金Projects(51078359,51208522,51208523)supported by the National Natural Science Foundation of ChinaProject(2010-122-009)supported by the Traffic Science and Technology Fund of Guizhou Province,ChinaProject(CX2011B098)supported by the Postgraduate Research Innovation Fund of Hunan Province,China
文摘Large amount of groundwater discharging from tunnel is likely to cause destruction of the ecological environment in the vicinity of the tunnel, thus an appropriate drainage criterion should be established to balance the tunnel construction and groundwater.To assess the related problems, an limiting drainage standard ranging from 0.5 to 2.0 m3/(m·d) was suggested for mountain tunnels based on survey and comparative analysis. After that, for the purpose of verifying the rationality of the standard, a calculated formula for dewatering funnel volume caused by drainage was deduced on the basis of the groundwater dynamics and experience method.Furthermore, the equation about the relationship between water discharge and drawdown of groundwater table was presented. The permeability coefficient, specific yield and groundwater table value were introduced, and then combined with the above equation, the drawdown of groundwater table under the proposed limiting drainage criterion was calculated. It is shown that the proposed drainage standard can reach the purpose of protecting ecological environment under the following two conditions. One is the permeability coefficient ranges from 10-4 to 10-5 m/s and the specific yield ranges from 0.1 to 0.001. The other is the permeability coefficient varies from 10-6 to 10-8 m/s and the specific yield varies from 0.1 to 0.01. In addition, a majority of common geotechnical layers are involved in the above ranges. Thus, the proposed limiting drainage standard which ranges from 0.5 to 2.0 m3/(m·d) for mountain tunnel is reasonable.
基金Supported by the National Science Council of China (Grant No.50878187)
文摘On May 12, 2008, a strong earthquake with a magnitude of 8.0 (Ms) struck Wenchuan town, in the eastern Sichuan area of west China. Following the earthquake on May 18, the Southwest Jiaotong University organized a damage survey team and dispatched it to the affected area for the investigation into the damage and collection of information and data. This paper outlines the findings of this investigation on the earthquake disaster to mountain tunnels and geotechnical engineering. The systematic investigation, involving geological conditions, design documents, construction and maintenance records of the tunnels, has been conducted and the degree of damage to investigated tunnels has been assessed according to the width and length of cracks, the stability of the slope above the tunnel, and the condition of the groundwater inrush. The results show that the major damage of the mountain tunnels was mainly concentrated in the tunnel portals due to widespread landslides and rockfalls, and the inner part of investigated tunnels suffered moderate damages mainly due to fault displacements. It is hoped that the information shared herein could enhance the outstanding of seismic behavior of mountain tunnels and improve seismic design and construction procedures.
文摘为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指标体系;其次,采用云模型将定性指标定量描述,并运用CRITIC(criteria importance though intercriteria correlation)确定指标权重;最后以灰色关联差异信息值为基础,结合欧几里得理论计算修正的加权靶心距,通过对比靶心距实现方案优选,并采用单因素轮换法(one-at-a-time,OAT)进行了指标敏感性分析。结果表明:最优方案的加权靶心距为0.610,评选出的方案与实际一致,并分析出“地形地貌改变”为对方案评选影响最大的指标。可见,该方法呈现了各方案的优劣,使山区隧道施工场地布置方案评选更科学、合理。