Safety Analysis for the Underground Pipelines Close to a Subway Foundation Pit under Small Soil Strains

摘要

Small strain stiffness properties of soil play an important role in predicting the deformation of deep foundation pit and tunnel excavation. Based on a case of safety analysis for surrounding pipelines adjacent to a deep excavation of subway station in Changzhou City, a two-dimensional finite element model to analyze this typical problem is proposed. Small-strain of soil is considered to investigate the effect on surrounding pipelines of deep pit excavation. Based a series of laboratory tests, the small strain properties of typical undisturbed soils in Changzhou are investigated and the related parameters involved in the hardening soil model combined with the small strain model (HSS) are determined. By comparing simulation results with the actual measurement, it shows that the deflection of retaining wall is obviously reduced when the small strain stiffness of soil is considered in numerical analysis. And the calculated result is much close to the observed. Meanwhile, a simplified analytical method for safety analysis of underground pipelines adjacent to the deep excavation is proposed and the applicability of HSS model is verified.