Abstract: With the acceleration of urbanization, the process of large-scale underground space development is also accelerated, and there will be a larger number of adjacent deep excavations at the same time or cross-construction. The support structure of adjacent deep excavations will produce complex deformation during the construction. The deformation of bracing structures in deep excavations using the top-down construction method is not only very important to the stability and safety of deep foundation, but also to the stability of underground and above-ground structures. The Beijing City Sub-Central Station Comprehensive Transportation Hub Project is presented in this paper as the case history. The measured data of deformation of columns in covered excavation of open cut deep excavation and semi-covered excavation deep excavation with common wall of the construction is analyzed. The PLAXIS software is used to simulate the entire process of adjacent deep excavation with common walls, and the deformation control measures of columns in the excavation with cover excavation area are proposed. The results show: (1) The maximum vertical deformation of the columns is 41mm, the deformation of columns shows large sides and small in the middle in the north-south direction, and small on both sides and large in the middle in the east-west direction; (2) The excavation of the adjacent excavations with common wall to the bottom of the excavation, the maximum horizontal deformation of each column is only 1.1mm, and the deformation direction is biased to the side of the open excavation area of pit 02B; (3) Reducing the head of confined-water (iii) to 9.8m elevation and increasing the embedment ratio of bored piles to 2.0 can effectively control the vertical deformation of columns; (4) When pit 03A is excavated first, the B1 floor slab can be constructed in advance so that the horizontal deformation of columns can be effectively controlled. The research results can provide some references and lessons for similar projects.

Key words: Common Wall, Deep Excavations, Deformation of Columns, Monitored Data, Control Measures