Engineering Application and In-situ Monitoring Analysis of Retaining Structures of New H-section Steel Support System in Foundation Pit

Abstract

A new H-section steel support system is introduced based on a foundation pit project in Shanghai. In-situ monitoring was carried out to measure the displacement of supporting piles. The monitoring results showed that the displacement of pile-top was closely related to the excavation depth and time. It is basically no longer developing after the foundation slab concreted finished. Horizontal displacement of the pile body increased gradually with the increase of excavation depth. The maximum horizontal displacement was about 25 mm and the position was about 1 m below the bottom of the foundation pit. Finally, the horizontal displacement of the pile body was presented as a "bow" with a small displacement at two ends and a large displacement in the middle. Compared with those at reinforced concrete support area, it showed that the deformation law and final displacement value of pile-top and pile body in the new H-section steel support area was basically the same as that of reinforced concrete support area. And all of the monitoring data were within the security range, meeting the design and code requirements. Moreover, new H-section steel support system construction period was short and the cost was low. It could effectively improve the green construction level. The conclusions obtained in this paper could be referred for other familiar projects.