Abstract: A 3D elastoplastic numerical model is developed for the structure-soil layers-pipeline system in the Gongyixiqiao metro station project of Beijing metro line 4, and used to analyze the deformation of pipeline and its surrounding soil, based on the measured displacement data. By combing the field monitoring data, numerical simulations and empirical formulations, the effects of pipeline stiffness on ground deformation are analyzed. It is shown that as the soil-pipe stiffness k is less than 0.18, the differential soil-pipe settlement is less than 5%, and the empirical formulation can be used to calculate the soil settlement at the level of pipeline axis. With the increase of pipeline stiffness, the pipeline can constrain the ground movement more significantly, resulting in a reduction of the growth rate of ground settlement or even a negative growth so that the surface settlement can even exceed the ground settlement. By a fitting analysis of the numerical results, a method is proposed for estimating the maximum pipeline settlement for rigidly jointed pipelines, which is based on the soil-pipe stiffness and tunnel-induced ground surface settlement. The method has been used to calculate an actual project settlement, and the difference between the calculated and measured values is found to be less than 4%, showing the applicability of the proposed method.

Key words: tunneling, ground settlement, pipeline settlement, soil-pipe interaction