Analysis of Foundation Pit Excavation Deformation and Parameter Influence of Pile-Anchor-Ribbed-Beam Support System

Abstract

The support system is the most important part of foundation pit engineering, which mainly determines the safety of foundation pit engineering. Based on the characteristics of the foundation pit of Changsha international financial center, the original pile-anchor-beam (PAB) support system is improved into a new form of support system, the pile-anchor-ribbed-beam (PARB) support system. This study establishes a numerical simulation model to calculate the surface settlement and the deformation of the retaining structure caused by the excavation of the foundation pit by using the PAB and PARB support systems, respectively. Finally, this study analyzes the influence of pile anchorage depth, ribbed beam size and waist beam size on the support effect. The field monitoring data are in good agreement with the numerical simulation results, which verifies the validity and accuracy of the numerical calculation model. The support effect of the new PARB support system is 30% higher than that of the original PAB support system. The position of maximum surface settlement is about 0.5 times the excavation depth from the retaining structure, and the position of maximum lateral deformation of the pile is about 0.9 times the excavation depth from the pile top. The increase in pile embedded depth and ribbed beam size can significantly improve the support effect, while the change of waist beam size does not improve the support effect significantly.