Design of composite foundation for high-rise buildings in complex red bed karst site

Abstract

Ground collapse occurs frequently in deep foundation construction in the shallow overlying rock-karst area, constituting a major hidden danger to personal safety and engineering quality. This study reveals the structural characteristics of honeycomb heterogeneous anisotropic rock mass through the geological radar scanning and the foundation optimization design of a high-rise building (35 floors) in the red layer karst site. Meanwhile, the giant karst cave pipeline is filled and reinforced by karst grouting, and an artificial dam is constructed to block the groundwater transport channel. Based on the analysis results of the stability against the punching and cutting of the karst cave roof, the composite foundation of the plain concrete rigid pile with low-bearing capacity and high replacement rate is proposed. Regarding the extremely thin karst cave roof area, the steel pipe pile is used for underpinning and reinforcement, effectively avoiding the risk of local instability and construction collapse caused by the effective length of the pile and large stress at the pile end. After completing the building, it runs well. Meanwhile, the monitoring shows that the maximum settlement deformation of the high-rise building is only 9.63 mm.