Abstract: To study the influence of karst rock cavity distribution and morphology on the stability of the supporting structure for a deep excavation as well as the ground settlement, a three-dimensional finite element model for the excavation engineering is established by using the commercial software Midas GTS NX. The influence of karst rock cavity diameter, locations, and in-fill material on the stability of the supporting structure it is analyzed. The results show that, when the distance between the karst rock cavity and the edge of excavation support is fixed, the maximum lateral displacement of the soldier piles and the maximum ground settlement gradually increase with the increase of karst rock cavity diameter. With the increase of the distance between the karst rock cavity and the supporting structure, the influence of the karst rock cavity on the lateral displacement of the soldier piles gradually decreases. The surface settlement caused by the karst rock cavity increases first and then decreases. The large-diameter karst rock cavity has an obvious influence on the in-fill material state and the stability of the supporting structure which needs to be grouted in time. The importance ranking of the influence of the karst rock cavity on the stability of the supporting structure is as follow: karst rock cavity diameter > karst rock cavity location > karst in-fill materials. With the increase of the deep excavation depth, the differential settlement of buildings surrounding the excavated area gradually increases, but the increase rate of the deformation gradually slows down and tends to be stable.

Key words: Deep Excavation, Karst Rock Cavities, Supporting Structure, Settlement, Stability