In-situ monitoring on deformation laws of deep foundation pit

The supporting plan and deformation monitoring plan are given and the in-situ monitoring study is completed on the foundation pit deformation,especially on the horizontal deformation of the foundation pit,the axial force of anchorage cable and the steel support.The result shows that the excavation depth and the exposed time without support of the foundation pit affect much on the deformation of the retaining piles,the tension force of the cables and the axial force of steel support.With the increment of excavation depth and the application of steel support,the deformation state of the retaining piles gradually develops from the anteverted curve towards foundation pit to bow curve.The horizontal deformation of the retaining piles and the axial force of the steel support increase with the increment of excavation depth.With the application of steel support,the horizontal deformation of the retaining piles and the tension force of cables become steady.The multiplex supporting plan consists of steel support,retaining piles and pre-stressed anchorage cable can control the deformation efficiently and assure a safe construction of subway station.