Abstract: Karst terrain is widely distributed in the southwest of China. Due to its “hard in upper strata and soft in lower strata” soil conditions and large variation in bedrock surface, the karst geology induces negative influences in the engineering projects. In this paper, the supporting system of the deep excavation in the complicated karst geological conditions in Lichuan City is evaluated. To ensure the safety and economy of the project, the additional local reinforcement system in the supporting system was used in resolving the stress concentration issues induced from the significant differences among adjacent soil and rock strata. Both the minimum pile length and the rock socket depth were used in the quality assurance of the soldier pile system. The results were proved to be satisfactory.

Key words: deep excavations, karst terrain, internal support, displacement