Research On The Cave Roof Stability Assessment Based On The Pile Foundation Load Of The Shenzhen Subway Engineering

Karst distributes widely in our country, it plays a vital influence on the security and stability of the building foundation in the Karst region. With the development of infrastructure in our country, the destructions of building caused by collapse in the based bottom of the cave in Karst region are facing the main geological problem, the Karst problem.This paper is based on actual engineering example—The grade separation bridge in the subway of Shenzhen. Because of the influence of cavern and cranny underground, the pile foundation of the bridge could not be constructed normally. The designer had to put the pile foundation on the cavern roof. Therefore, the stability assessment of cave engineering geological conditions become the main geological problem.Based on the Shenzhen Metro cave investigation and disease treatment and the related typically Karst caves engineering project, based on the current common methods solving cave collapse, this paper establishes a cave subsiding model, calculates and analyzes the stability of closed roof cave, then analyzes the factors that influence the stability of roof in the closed roof cave, this paper quantitatively calculates the bearing capacity of foundation soil in the bottom of the cave basis.Firstly, this paper studies the reasons of the subsiding of cavern and predigests the interactional system between the pile and the cavern to a simple model. Based on the simple model, this paper analyzes the stability of the cavern roof with traditional calculation.Secondly, this paper simulates the interactional system between the pile and the cavern with FLAC3D. Then, the paper compares the result of numerical simulation with the result of traditional calculation what has been draw before, and analyzes the stability of cavern.Lastly, with both the numerical simulation and traditional calculation, this paper analyzes the influence factor of the stability of cavern, and then it analyzes the impressionable factor what influence the stability of cavern by compare with other factors.