Study On The Influence Of Excavation Of Foundation On Stability Of Adjacent Tunnel With Pressure Arch

The excavation of building deep foundation is a common case near the existing tunnel. Subway tunnel as the main traffic arteries of city has strict deformation requirements. The process of excavation will cause deformation of adjacent tunnel, affect the normal operation of tunnel, can also cause serious damage to the tunnel lining structure and create a threat to safety operation of tunnel. So the study on the influence of excavation of deep foundation on stability of adjacent tunnel has important academic value and practical significance.This paper studies the regularity of surrounding rock and soil pressure arch and stability of tunnel during the excavation of deep foundation with pressure arch with the means of theoretical analysis and numerical simulation. The influence of factors on stability of tunnel is analyzed, and reinforcement measures are discussed during the excavation of foundation. The main conclusions are as follows:(1) The pressure arch boundary of adjacent tunnel changes after excavation. With the depth of excavation increasing, the distance of tunnel pressure arch inner boundary increases, the pressure arch inner boundary of tunnel waist has not changed at the edge of tunnel. The distance of tunnel pressure arch outer boundary decreases, especially the tunnel left waist has the maximum decrease.(2) The changes of tunnel pressure arch inner and outer boundary have a close relationship with the stability of tunnel during the excavation of foundation. The displacement and stress of tunnel increase as the distance of tunnel pressure arch inner boundary increases and tunnel pressure arch outer boundary decreases. The stability of tunnel get worse when tunnel pressure arch is impacted heavily and the shape of pressure arch become more irregular.(3) The distance of tunnel pressure arch inner boundary increases and pressure arch outer boundary decreases as the foundation depth and length increase and the distance between foundation and tunnel decreases. And the stability of tunnel get worse.(4) The distance of tunnel pressure arch inner boundary decreases and the distance of pressure arch outer boundary increases after the bottom of foundation was reinforced. It is feasible to use pressure arch to evaluate the stability of tunnel and choose the economic and effective reinforcing method.