极端降雨对黄土沟壑区隧洞施工 力学效应影响分析.

Rainfall infiltration greatly affects the stability of the surrounding rock in the construction of water tunnels in loess areas. The unsaturated seepage theory and numerical simulation method were used to study the deformation and seepage field evolution of the surrounding rock under the coupling influence of extreme rainfall infiltration and the excavation disturbance of loess gully area tunnel, and the coupled flow-solidity analysis was carried out through the Plaxis3D model to analyze the mechanical properties of the surrounding rock and the initial support process in the construction of Xin'ao method under rainfall infiltration. The results show that the higher the rainfall level is, the larger the pore water pressure change of the surrounding rock is, and the more unfavorable it is to the stability of the surrounding rock, rainfall infiltration and excavation disturbance will accelerate the redistribution process of seepage and stress fields in the soil layer. Based on the catchment characteristics of the trench, the water content of the surrounding rock of the tunnel shows a stepwise increase in the first 5~10 d, and the maximum deformations at the top of the arch, the waist of the arch, and the toe of the arch are 17. 8 mm, 28. 2 mm, and 24. 6 mm, with maximum shear deformations at the top, waist, and toe of the arch, 24. 6 mm, the maximum shear stress is 150. 6 kPa, 182. 5 kPa, 175. 3 kPa, rainfall end about 15~20 d perimeter rock deformation rate gradually reduce convergence to a specific value, but the stress of the perimeter rock continues to increase, in order to avoid plastic deformation of the perimeter rock, so can be carried out in the 15~20 d of the second lining support. The results of this study can provide reference for the safety control of tunnel construction in loess gully area during extreme rainfall. [ABSTRACT FROM AUTHOR]