Abstract:Most of the existing studies on the influence of foundation pit excavation on adjacent tunnels are based on displacement deformation and surface settlement. Few studies analyze the influence of foundation pit on the stability of surrounding rock above lateral tunnels from the surrounding rock "pressure arch". Based on the principle of stress path method and using ANSYS finite element numerical simulation, this paper studies the influence of three factors, namely, different depth, different width of foundation pit, different net distance between foundation pit and tunnel, on the internal and external boundaries of adjacent tunnel and surrounding rock pressure arch above. The conclusions are as follows: the sensitivity of the inner and outer boundary of pressure arch above the existing tunnel affected by different depths, widths and net distances of the newly built foundation pit on the side is lower than that of the newly built tunnel affected by different depths, widths and net distances of the existing foundation pit on the side, and the biggest difference in sensitivity is the width of the foundation pit. The internal boundary added value “Δh” is introduced to calculate the vertical uniform load of the tunnel under the influence of the foundation pit, and it is determined whether the surrounding rock is arched, the depth of the tunnel is re-determined, and a certain reference value is listed.This study can provide a reference for the stability and safety study of the tunnel adjacent to the foundation pit construction.