| Abstract:Through a circular deep foundation pit with a diameter of 10.0m and a depth of 24.50m in the eastern suburb of Xi'an, in order to solve the problem of excavating a pipe jacking well with a small size and a large depth in the loess collapsible under overburden pressure area of multi-storey buildings. which is extremely sensitive to deformation in the surrounding environment with extremely complex conditions, no anchor cable construction space, and close proximity to the working well. The earth pressure is resisted by the circular reinforced concrete instead of the traditional inner support, which does not affect the excavation of the narrow space, but also controls the deformation of the enclosure structure and protects the safety of the surrounding environment. At present, the project has been completed. Several engineering practices show that in a circular deep foundation pit with a diameter of less than 12m and a depth of no more than 25m,the designed system has low cost, small deformation of the enclosure structure, safe and reliable surrounding environment, no anchor rod (cable) residue in the soil, and no impact on the later development and utilization of the adjacent underground space, which provides reference for excavating similar deep foundation pits in the loess collapsible under overburden pressure area with significance. |