Proportion Analysis of Ground Settlement Caused by Excavation and Dewatering of A Deep Excavation in Sand Area

Abstract

Ground settlement caused by combined influence of excavation and dewatering in sand area is discussed in this paper. The soil seepage-stress interaction model in a deep excavation is established based on the modified Mohr–Coulomb model using finite element theory, in order to analyze seepage field and ground settlement surrounding the deep excavation caused by well dewatering and soil excavation. Ground settlement caused by excavation and dewatering individually are obtained from the numerical investigation. A case history in northeastern China is adopted in this study, and the results show that, impact of ground settlement caused by excavation and dewatering is about three times the excavation depth (H). The maximum settlement point of monitoring sections appears at a distance of 22 m from the deep excavation, about 0.82–0.96 H. The ground settlement caused by soil excavation is dominant from 10 to 20 m away from the deep excavation, while the ground settlement beyond 25 m from the excavation is mainly caused by dewatering. Settlement caused by dewatering is kind of irreversible settlement, so the ground settlement of a deep excavation caused by well dewatering can not be ignored during design and construction of excavation engineering.