LIQUID-SOLID COUPLING RESPONSE OF SURROUNDING ROCK MASS OF LARGE-DIAMETER RIVER-CROSSING SHIELD TUNNEL

Abstract

The purpose is to investigate the response of seepage field, displacement field and stress field in the surrounding rock mass during dynamic tunneling in soft soil area. Relied on a large-diameter river-crossing shield tunnel project, considering driving force, shield tail grouting pressure, and the friction resistance between the shield shell and the soil, a three-dimensional fine tunnel model considering the liquid-solid coupling effect in the soil during dynamic tunneling was established by employing the finite difference method. The response characteristics of pore water pressure, displacement and stress in the surrounding rock mass were obtained. The results show that during shield tunneling and shield tail grouting, the pore water pressure in the range of 0.5 times the hole diameter around the tunnel decreases and increases respectively due to the liquid-solid coupling in the surrounding rock mass. When the shield tunneling moves away, the pore water pressure of the soil near the vault decreases, and the pore water pressure near the tunnel arch bottom increases. The impact range of shield tail grouting on the vertical settlement of the upper soil is about 0.5 times the hole diameter. The shield tail grouting can effectively reduce the vertical settlement of the top soil and slow down the vertical uplift of the bottom soil. During shield tunneling the vertical stress distribution of the soil above the vault of the working position and around the excavation surface is funnel-shaped, and the vertical stress around the excavated tunnel decreases.