Abstract: Currently, the simplified analysis for the deformation response of adjacent piles by excavation has seldom considered the influence of supporting action, especially the geotechnical influence caused by the rainfall environment. Based on the stratified hypothetical Green-Ampt model applicable to different rainfall conditions to simulate the rainfall infiltration process, a two-stage method was proposed to analyze the interaction between the excavation and the adjacent pile under the influence of rainfall. In the first stage, considering the influence of soil unloading, retaining, and supporting of excavation, the Mindlin solution was used to analyze the additional stresses in the soil at the adjacent pile foundations caused by the excavation of the foundation pit under the rainfall. In the second stage, based on the Pasternak foundation model, the interaction between pile foundations and soil was explored to obtain the horizontal deformation response of single piles and groups of piles under the influence of rainfall with the rainfall duration. The monitoring data from existing engineering were compared to the theoretical calculation results with good agreements. In addition, the parameters of rainfall (rainfall intensity, saturated permeability coefficient, initial water content, matric suction) and pile (boundary conditions, brace stiffness, pile diameter, excavation depth, distance between piles and foundation pit) were analyzed to investigate the influences on pile deformation. The results show that the proposed theoretical method can better reflect the deformation response of foundation excavation on adjacent pile foundations under the rainfall. The rainfall has a significant influence on the deformation of the adjacent pile, and the sensitivity of rainfall parameters is as follows: rainfall intensity > initial water content > saturated permeability coefficient > matric suction. With the increase of the rainfall duration, the development depth of the wet front continues to increase, and its development rate shows a gradual weakening law until it approaches the saturated permeability coefficient. The displacement of adjacent piles caused by the excavation becomes larger and larger, and the change rate of the top displacement first gradually decreases and then converges to a specific value. The smaller the support stiffness and pile-excavation distance, the greater the influence of rainfall duration on piles. The influence of rainfall duration on piles with different pile diameters is basically the same. The greater the excavation depth, the greater the influence of rainfall duration on piles.

Key words: rainfall, Green-Ampt model, foundation pit excavation, brace stiffness, response of pile deformation, Pasternak foundation model