Dynamic response characteristics and instability mechanism of layered surrounding rock tunnels affected by geostress under dynamic and static loads

Abstract

Ensuring the safe excavation of layered surrounding rock tunnels requires a comprehension of the dynamic response characteristics and instability mechanism of the rock under dynamic and static loads. The impact of variations in geostress on tunnel stability is a concern that cannot be disregarded as long-distance tunnel construction continues to grow. This paper provides a detailed description of the maximum principal stress dynamic response and deformation characteristics of the tunnel's layered surrounding rock with the change of geostress under dynamic and static loads using model tests and numerical simulation methods. The effects of different loads, different geostress, different locations, and different failure modes on the maximum principal stress and displacement of the tunnel's layered surrounding rock are comparatively analyzed. A prediction model of the maximum principal stress and maximum displacement of the layered surrounding rock affected by geostress under the dynamic load is proposed by dimensional analysis. At last, based on the prediction model, the critical lateral pressure coefficient was obtained to be 0.74 and the maximum displacement of 12.98 mm appears at the left spandrel when the tunnel depth reaches the maximum of 963 m.