Monitoring Analysis on the Surrounding Deformation of Super Deep Foundation Pit during the Whole Construction Process in Urban Dense Area

It is very important to analyze and control the environmental deformation in the whole process of super deep foundation pit construction in dense urban areas. Taking the whole construction process of a super-deep foundation pit in Hangzhou as an example, the surface settlement, lateral displacement of diaphragm wall, settlement of adjacent buildings and settlement of pipelines in the construction stage of supporting structure, excavation stage of foundation pit and demolition stage of supporting structure are measured and statistically analyzed. It is found that the maximum lateral displacement of the wall remains basically unchanged after the pouring of the foundation pit floor, which is located at 0.8 times the excavation depth, while the maximum lateral displacement continues to increase slightly during the support demolition stage, and the increase can reach 10% of the cumulative lateral displacement. Ground settlement, adjacent building settlement and pipeline settlement still show a continuous development trend after the completion of foundation pit construction. For the wall lateral displacement, surface settlement, settlement of adjacent buildings and pipeline settlement, the proportion of each construction stage is generally in the order of foundation pit excavation stage > support demolition stage > enclosure construction stage. Wall lateral displacement and surface settlement are mainly generated in the foundation pit excavation stage. The proportion of foundation pit excavation stage reaches more than 60%, up to 91.95%; the deformation of adjacent buildings and the settlement of pipelines are mainly generated in the stage of foundation pit excavation and enclosure construction. The proportion of foundation pit excavation stage is mostly about 60%, and the proportion of support demolition stage can also reach more than 30%.