Research on Design of Foundation Pit Support for Suspended Wall in Soil and Rock Dual Structure Stratum Area

With the deepening of the excavation depth of foundation pits, the geological conditions tend to become more complicated, and the forms of supporting structures tend to be diversified. Taking Guangzhou Metro Line 21 Yuancun Station as an example, for the soil-rock dual structure strata area, the foundation pit can be divided into two upper and lower sections for calculation. The upper section adopts the wall of "suspended base underground continuous wall + inner support (anchor cable)" supporting (anchor) system, and the lower section adopts the rock slope anchoring shotcrete system. The calculation results are compared with the on-site monitoring results. The results show that: (1)The recommended algorithm is suitable for the calculation of the suspended wall of the soil and rock dual structure; (2)The foot lock anchor cable of suspended wall has an obvious control effect on the horizontal displacement of the wall foot, which is greatly affected by the prestress of the anchor cable; (3)The supporting system of the suspended wall can effectively save construction period and investment, and the deformation of the foundation pit is about 15% compared with that of the conventional foundation pit.