The Effect of Center Diaphragm Excavation Method and Auxiliary Construction on Surface Settlement of Shallow-Buried Tunnels

Abstract

Previous works have shown that for the excavation of underpasses, the selection of appropriate excavation and construction methods has a significant impact on the surface settlement. The result of research showed that shallow tunnelling method usually has the characteristics of large investment scale, long time limit, complex and diverse construction technology, and great mutual influence of surrounding environment. Therefore, this project adopted CD method for initial excavation, and adopted the full-section overburden grouting method for the later stage to limit the surface settlement. The results showed that the surface settlement caused by hole1 and 3 accounted for 65.9 % of the total surface settlement, while the surface settlement caused by hole1 3 and 4 was 22.4% and 2.5%, respectively. After using the full-section overburden grouting method. At the corresponding excavation stage, the surface settlement caused by the new process was obviously lower than that of the old process. Among them, during the excavation of hole 1, the surface settlement value was reduced by 15.47% compared with the old process, indicating that the use of the new process can greatly reduce the surface settlement value and improve the engineering quality of the underground tunnel.