The Solution to the Safety Factor of Vertical Shaft Enclosure with One-Side Elevation Angle Based on FLAC3D

Abstract

The enclosure structure of the vertical shaft of subway engineering is generally vertical, and perpendicular to the plane. Due to the effects of the geological condition, the construction condition and the supporting method, the shaft reflects similar deformation characteristics to the enclosure structure of foundation pit. Generally, the enclosure structure deformation can be decomposed into three types, namely the forward rotation, reverse rotation and deflection. When the vertical shaft enclosure structure produces a forward rotation with a lesser degree, it can still be used for positive angle slope processing, which enables us to calculate the safety factor of one side with positive angle enclosure structure in the same way with the slope of foundation pit. Taking the shield-receiving shaft of Dalian Jiaotong university station, Dalian metro No.2, Section 201 as an example, it is the geological conditions and supporting structure that contribute to build the enclosure structure with one-side elevation angle. Based on the above method and taking the geological, construction and supporting conditions into account, FLAC3D is used to build the model, and carry out the solution on safety factor of the enclosure structure with positive angle. The results indicate that under the existing conditions, the enclosure structure safety factor for our example is more than 1.