English：

Based on field monitoring of a deep foundation excavation constructed adjacent to existingbuilding, together with the establishment of a corresponding three⁃dimensional finite element model of theexcavation, the deformation evolution of both the foundation excavation and existing buildings duringexcavation was investigated. The influences of pile diameter, pile spacing, and horizontal spacing ofinternal supports on the deformation behavior of the foundation excavation and adjacent building wereanalyzed, and the support system was optimized accordingly. The results indicate that the horizontaldisplacement of retaining piles, as well as the horizontal displacement and settlement of existing building,increase with excavation depth. The horizontal displacement of piles first increases and then decreaseswith depth, with the maximum value occurring at a depth of 16m. Larger horizontal displacements of pilesare observed in zones close to the existing building. Horizontal displacement of existing building increaseswith building height, while the settlement decreases with increasing distance from the excavation edge.The existing building remained in a relatively safe condition throughout the excavation process. Both pilehorizontal displacement and building settlement decrease with increasing pile diameter, but increase withlarger pile spacing and greater horizontal spacing of internal supports. It is recommended that theretaining piles adopt a diameter of 1 200mm, a pile spacing of 1 000mm, and an internal supporthorizontal spacing of 3m. Under these conditions, the maximum pile horizontal displacement is 30.7mmand the building settlement is 18. 4mm, representing reductions of approximately 17% and 12%,respectively, compared with the original support scheme.