Monitoring and numerical simulation of support for foundation pit at Yanyuan Road Station of Lanzhou Metro

The unique water-rich red sandstone stratum in Lanzhou area is easy to disintegrate when excavated and exposed, and the excavation and dewatering of foundation pits are extremely difficult.There is still no complete design and construction experience for reference.Taking the deep foundation pit at Yanyuan Road Station of Lanzhou Metro as an example, by analyzing the surrounding building environment, engineering geology and hydrological conditions, a suitable supporting structure system of diaphragm wall and internal support for deep foundation pits of red sandstone is put forward.The monitoring data of deformation of supporting structure and surrounding environment during the construction of the foundation pit are analyzed, and the finite element software MIDAS GTS is used to simulate the excavation process.The results show that the deformation of each measuring point is within the safety control range, which means that the selection of supporting structure of the foundation pit is reasonable.They may provide experience and technical support for the design of supporting structure of similar foundation pits of red sandstone encountered in the subsequent construction of Lanzhou Metro.