Monitoring and numerical simulation analysis of support structures of deep foundation pit in special red sandstone stratum in Lanzhou

There are great differences in the disintegration of red sandstone strata encountered in different sites during the excavation of Lanzhou Metro, and the researches on the support methods for deep foundation pits in different types of red sandstone are urgently needed. Taking the deep foundation pit of a station in disintegrated red sandstone as an example, through the analysis of the special engineering geological and hydrological conditions of the site, it is proposed that the support structures of interlocking piles and internal supports are suitable. The monitoring data of the support structures and the deformation of the surrounding environment during the construction of foundation pit are analyzed. The numerical model Midas GTS is established for the excavation process, and the monitoring and simulated values are compared and analyzed. The results show that the deformation of each item is within the scope of safety control, indicating that the scheme of support structures for the foundation pit of the station is reasonable and effective. The research results may guide the support design of deep foundation pits in similar red sandstone in Lanzhou Metro.