基于突变理论的隧道洞口浅埋段软弱围岩失稳分析方法  

Instability Analysis Method of Weak Surrounding Rock in Shallow-Buried Section of Tunnel Portal Based on Catastrophe Theory

作　　者：陈舞 岳克栋 王浩[1] 张国华[1] 覃卫民[1] CHEN Wu;YUE Kedong;WANG Hao;ZHANG Guohua;QIN Weimin(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Changjiang Institute of Survey,Planning,Design and Research Co.,Ltd.,Wuhan Hubei 430010,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049 [3]长江勘测规划设计研究有限责任公司,湖北武汉430010

出　　处：《中国铁道科学》2021年第4期69-77,共9页China Railway Science

基　　金：国家自然科学基金重点资助项目(41731284);国家自然科学基金面上资助项目(51579235,41472288)。

摘　　要：针对隧道洞口浅埋段多位于覆盖层、坡积层或风化严重的软弱破碎岩体中,极易发生失稳破坏的现实问题,以某隧道为工程背景,提出1种基于突变理论的隧道洞口浅埋段软弱围岩失稳分析方法。根据隧道围岩失稳情况,建立隧道洞口浅埋段围岩力学模型,采用Weibull分布函数,描述隧道上覆软弱地层的本构关系;根据总势能原理建立围岩失稳破坏的尖点突变模型,导出围岩失稳的力学判据;将地表沉降监测数据和尖点突变模型进行有效融合,建立隧道围岩稳定性预测模型,导出围岩稳定性判别式;以隧道5处典型断面为例,选取出现明显失稳征兆之前的7 d监测数据进行验证。结果表明:隧道洞口浅埋段围岩失稳与上覆地层的应变软化程度、刚度比及含水率相关;隧道围岩失稳力学判据和稳定性判别式的判别结果与现场实际围岩情况一致;利用地表沉降数据建立的围岩稳定性判别式来预测围岩的稳定性是合理可行的。In view of the fact that the shallow-buried section of tunnel portal is mostly located in overburden layer,slope layer or fractured weak rock with severe weathering,which is prone to instability and failure,an instability analysis method for weak surrounding rock in shallow-buried section of tunnel portal based on catastrophe theory is proposed,with a tunnel as the engineering background.According to the instability condition of tunnel surrounding rock,a mechanical model for the shallow-buried section of the tunnel portal is established,and the Weibull distribution function is used to describe the constitutive relationship of the weak strata overlying the tunnel.Based on the principle of total potential energy,the cusp catastrophe model of surrounding rock instability is established,and the mechanical criterion of surrounding rock instability is derived.Based on the effective fusion of the monitoring data of ground settlement and cusp catastrophe model,the prediction model of tunnel surrounding rock stability is established,and the discriminant of surrounding rock stability is derived.Taking 5 typical sections of the tunnel as an example,the monitoring data of 7 days before the obvious signs of instability are selected for verification.The results show that the instability of surrounding rock in shallow-buried section of tunnel portal is related to the strain softening degree,stiffness ratio and water content of the overlying strata.The results of the instability mechanical criterion and stability discriminant of tunnel surrounding rock are consistent with the actual situation of surrounding rock on site.Therefore,it is reasonable and feasible to predict the stability of surrounding rock by using the discriminant of surrounding rock stability based on ground settlement data.

关 键 词：隧道洞口 浅埋段 围岩失稳 尖点突变模型 地表沉降 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]