Abstract:

The stability of the support structure is very important when two adjacent foundation pits are excavated at a same time. The foundation pit of entrance/exit No. 1 of Shuangshan Station on Qingdao Metro Line No. 3 and that of Cade Commercial Mansion are excavated at the same time; and the covered drains can not be removed. As a result, a supporting system of doublerow piles + anchor cable is proposed. The supporting structure consists of doublerow piles, pull bolt body, vertical anchor cable and oblique anchor cable. The stability of single row, sliding of double row and stability of collapseresistance are calculated and analyzed by limit equilibrium analysis method; and the displacement/deformation of the foundation pits are monitored. The results show that the foundation pit stability calculation results can meet the requirements of related specifications; the displacement of pile top (maximum horizontal displacement of 7.20 mm) and the deformation of ground surface (maximum ground settlement of 5.26 mm) can meet the related requirements, so as to show that the abovementioned supporting system is rational and can provide reference for similar projects in the future.

Key words: foundation pit support, similar doublerow piles, pull bolt body, vertical anchor cable, limit equilibrium analysis method, Rankine earth pressure theory