Abstract：
A large cave in front of the tunnel face in a karst area makes for a very large construction risk. It is very important to keep a reasonable laccolith thickness in front of the tunnel face and to use support in advance of the face during the construction of a karst tunnel. This study analyzes the factors affecting the safe distance between a tunnel face and karst cave by means of numerical simulation and theoretical calculation and establishes the calculation methods (empirical, analogue, theoretical calculation, and numerical analysis) plus computation schemes and formulas for predicting a safe thickness of laccolith in front of the tunnel face. Additionally, the analysis of a project case is carried out based on theoretical calculation and numerical simulation.
2012, Vol. 49 