A new method determining safe thickness of karst cave roof under pile tip

JIANG Chong(蒋冲), LIU Lang(刘浪), WU Jun-ping(吴均平)

(School of Resources and Safety Engineering, Central South University, Changsha 410083, China)

Abstract:Cave roofs are used to support pile foundation in many engineering projects. Accurate stability analysis method of cave roof under pile tip is important in order to ensure the safety of the pile foundation structure. Firstly the mechanical model to analysis the stability of cave roof under pile tip is founded aiming to solve the problems that the simplified mechanical model has. Secondly, the boundary of cave roof is simply supposed to be supported according to the integrity of the rock mass in the boundary of cave roof. Thirdly, based on the theory of plates and shells, the simplified model is calculated and the theoretical calculation formula to determine the safe thickness of cave roof under pile tip can be obtained when the edges of the cave roof are simply supported. In the end, the analysis of the practical engineering project proves the feasibility and the rationality of the method which can be a new method to calculate the safe thickness of cave roof under pile tip.

Key words:karst; cave roof; theory of plates and shells; pile; safe thickness