Abstract: The high groundwater level and the poor stability in the coastal karst strata are frequently encountered. It is difficult to construct the foundation pit of the subway station. In order to improve the stability and safety of the deep foundation pit process of the subway, taking Ganjingzi Station foundation pit project of Dalian Metro Line 5 as an example, this paper analyzes the construction method and technology of pile-anchor support structure according to the complicated geological conditions of coastal karst and the characteristics of surrounding buildings and pipelines. Based on the field monitoring data, lateral displacement of retaining piles, the development of uneven settlement of ground and around building (structures) was analyzed. During the construction of deep foundation pit, the supporting structure is stable and safe, the uneven settlement of the surface and surrounding buildings (structures) is within the controllable range, and the pile anchor supporting structure has strong adaptability and reliability, which can provide a reference for the construction of subway stations in karst strata.

Key words: Deep Excavation, Karst, Soldier Pile-Anchor Support, Construction Technique, Gray Theory