Influence Analysis of Large Diameter Shield Tunneling under Building Pile Foundation in Sand-cobble Layer

In view of the disturbance to the buildings caused by the underpass of a subway shield in Chengdu sandy cobble layer, a numerical analysis model of the irregular buildings under the double track shield was established with MIDASGTSNX software, and the laws of the building surface subsidence and the pile foundation stress redistribution caused by the large-diameter shield tunnel during the underpass of the buildings were analyzed. The results show that the surface settlement curve changes into a concave settlement trough. The deformation of the four corners of the building after construction is affected by the height of the building, resulting in uneven settlement. The bottom of the independent foundation of the building is under pressure, and stress concentration occurs at the pile foundation position at the junction of the first and third floor buildings.