Abstract: Horizontal displacement of retaining structure is the main cause of ground surface settlement in deep excavation. In this paper we propose a method of estimating the ground surface settlement. First of all we assume that the ground surface settlement curve is a Gaussian probability density function, and derived the analytical formula of ground settlement under different lateral deformation modes of retaining wall based on linear elastic theory. Subsequently we acquired the location x_m of maximum settlement (which is defined as the distance x_m from the location of maximum settlement to foundation pit edge) in clay stratum based on the analytical formula, and then calculated the settlement-influenced range x₀ based on the aforementioned assumed function of ground settlement in association with soil loss theory. Furthermore, we derived the area A_v enveloped by the ground settlement curve, and in the meantime obtained the maximum ground settlement δ_max according to the relation between A_v and A_h, which is the area enveloped by the lateral displacement curve of retaining wall. The ground settlement of arbitrary location behind retaining wall hence can be estimated by substituting δ_max in the aforementioned assumed function. Through several engineering cases we proved that the proposed method is applicable, and thus providing a semi-theoretical and semi-empirical approach to predicting ground surface settlement.

Key words: ground surface settlement prediction, deep foundation pit, clay stratum, horizontal displacement of retaining wall, analytical solution, the soil loss theory