Determination of additional load on the bridge foundation pile under karst deformation

Abstract

It is necessary to assess the additional loads transferred to the piles during the growth of a karst cavity in karst soils for designing bridge support pile foundations in karst areas. Additional loads arise due to the displacement of the soil mass above the cavity and the emergence of “negative friction” forces on the pile lateral surface. The paper proposes a method for determining the additional load on the pile depending on the distance from the pile bottom to the karst soil roof and the predicted diameter of the cavity in karst soils. A method for numerical variation calculations based on the analysis of the change of shear stresses on the pile lateral surface at different stages of loading with the growth of a cavity and the stable arch over the cavity is proposed. The correct design model and criteria for stability evaluation of the arch over the cavity are selected. A series of numerical calculations are made. An analytical solution to determine the additional load on the pile depending on the distance from the pile bottom to the karst soil roof and the predicted diameter of the cavity in karst soils is obtained.