Study on mechanical response and disturbance control of shield underpass pre-reinforcement soil

Based on the construction method of reserved underpass space for shield tunneling and Hangzhou Metro Line 7 under Qianjiang Century City construction project. A three-dimensional calculation model of soil reinforcement with reserved underpass space was established by using numerical simulation method, and the mechanical disturbance of soil around the tunnel during the shield tunneling process was analyzed. The results show that under the condition of local soil reinforcement, heave deformation exists in the strengthened area, resulting in a large relative displacement between the local strengthened area and surrounding soil. That results in stress concentration at the interface between the reinforcement area and the surrounding soil. The isolation and protection effect of the diaphragm wall and reducing pile on the soil is revealed by monitoring the displacement.