Response of disturbed strata in tunnel construction considering influences of rainfall

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 infiltration rate 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 a gradual 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.