考虑降雨因素影响的隧道施工扰动地层响应分析

Response of disturbed strata in tunnel construction considering influences of rainfall

目前关于降雨影响在土建工程上的应用研究一般是针对边坡稳定性,还较少考虑对隧道开挖的土工影响,尤其是力学解析机理研究还非常少见。基于分层假定Green-Ampt模型来模拟降雨入渗过程,采用复变函数理论对雨浸地层进行分区映射计算,尝试提出了降雨影响下隧道开挖引起的周围地层位移场和应力场理论分析方法。此外,利用既有工程监测数据与理论解析结果进行对比,验证了所提出方法的可靠性。最后,通过参数分析,获取降雨强度、降雨历时、饱和渗透系数以及饱和层基质吸力等主要降雨参数对降雨区域隧道开挖诱发地层变形的影响规律。结果表明:所提出的理论方法可以较好反映降雨作用下隧道施工对扰动地层响应的影响。降雨强度和饱和层基质吸力对地层变形影响显著,而饱和渗透系数对雨浸地层入渗速率及变形速率有较大影响;随着降雨历时的增长,湿润锋发展深度不断增大且最终趋于稳定,而发展速率呈现出逐渐衰弱直至为零的规律,隧道开挖引起的地层变形也随之越来越大,其位移变化速率呈现出逐渐减小收敛至某一特定值的规律。研究成果对多雨地区、降雨灾害气候下隧道施工控制具有一定理论指导意义。

At present,the researches on the application of rainfall influences in civil engineering are generally on the slope stability,and the geotechnical impact on tunnel excavation is less considered,especially the theoretical analytical method is relatively rare.Based on the Green-Ampt model under the assumption of stratification to simulate the rainfall infiltration process,the complex function theory is used to calculate the partition mapping for the rainfall infiltration region.The theoretical analysis method for displacement and stress fields of the surrounding soils caused by tunnel excavation is firstly proposed considering the influences of rainfall.In addition,the reliability of the proposed analytical solution is verified by comparing the monitoring data from the existing projects.Finally,the sensitivity analysis of parameters,such as the rainfall intensity,rainfall duration,saturated permeability and matric suction,is carried out to observe the influences of soil deformation induced by tunneling in rainy days.The results show that the proposed theoretical method can better reflect the influences of tunnel excavation on the response of the surrounding soil under the action of rainfall.The rainfall intensity and matric suction have significant influences on the soil deformation,while the saturated permeability coefficient has great influences on the infiltrationrate and deformation rate in the rainfall infiltration region.With the increase of the rainfall duration,the development depth of the wetting front continues to increase and eventually stabilizes,and its development rate shows agradual weakening law until it reaches zero.The vertical displacements of ground caused by tunnel excavation also increase,and the change rate of displacement shows the law of decreasing gradually and converging to a certain value.The research results can give a reference for the control of tunnel construction under the climate of rainfall disasters or in abundant rainy areas.