Abstract: In order to thoroughly study the influence of the ultra-deep foundation pit excavation on the surrounding environment, the settlement of the surrounding buildings, pipeline settlement, road settlement and deformation of the different retaining structures caused by the excavation of deep foundation pit of a metro station were systematically monitored. The variation law of monitoring results was analyzed, and the numerical simulation was carried out with a finite element software to compare and verify the deformation influence of the foundation pit excavation on the different retaining structures and surrounding environment. The results show that the maximum settlement around the foundation pit is about 0.08%H (H is the excavation depth of the foundation pit), and the maximum horizontal displacement of the piles is about 0.07%H. When the upper part of the strata is the soil and the lower part is the rock with good mechanical properties within the excavation depth of a deep foundation pit, using the h-type piles support structure can reduce the horizontal displacement of the deep soil by about 40% compared with normal piles. Because the front row of the h-type piles is embedded in the rock with good mechanical properties, the horizontal displacement of the pile is small and the structure is stable during excavation. Using the h-type piles as the retaining structure can reduce the construction difficulty and shorten the construction period. Therefore, it is advantageous to use the h-type piles for the retaining structure in similar strata.

Key words: metro station, deep foundation pit, the h-type pile, deformationmonitoring, influence analysis