Research on the Influence of Reinforcement Width at the Bottom of the Pit on Foundation Pit Deformation and Ground Surface Settlement

DOI

10.2991/978-94-6463-856-1_5How to use a DOI?

Keywords

Pit deformation; Surface subsidence; Bottom reinforcement of the pit; Three dimensional finite element model; Passive zone soil reinforcement; Rotary jet grouting pile; Enclosure structure

Abstract

Since the beginning of the 21st century, artificial islands made of dredged soil and hydraulic fill from port waterways have become one of the main land uses for engineering construction. Such sites are usually located beneath deep marine silt layers, which are mostly saturated, soft plastic to flow plastic, with low bearing capacity, high compressibility, and poor permeability. Strengthening measures need to be taken before excavation of foundation pits in these areas. There are various techniques and methods for reinforcing soil in the passive zone of foundation pits. Currently, widely used methods include grouting, drainage consolidation, cement soil mixing, and high-pressure rotary spraying. Many experts and scholars at home and abroad have also conducted a series of valuable research on passive zone reinforcement technology. This paper explores the impact of the width of the bottom reinforcement on the deformation of foundation pits and the surface settlement, taking the deep foundation pit project of Block B6 in Area A of Macao New City Reclamation as a case. The study finds that the reinforcement of the soil in the passive zone has a remarkable effect on controlling the deformation of the foundation pit, and there exists an optimal reinforcement scope. Through the simulation of a three-dimensional finite element model, the deformation of the retaining structure of the foundation pit, the surface settlement outside the pit, and the heave at the bottom of the pit under different reinforcement scopes were compared. The results indicate that the reinforcement at the bottom of the foundation pit can significantly reduce the lateral deformation of the foundation pit, and the optimal reinforcement width is 6 to 8 m. Beyond this range, the reinforcement effect is not significant. Meanwhile, the amount of surface settlement and the heave at the bottom of the pit decrease with the expansion of the reinforcement scope, but it is not economically feasible to expand the reinforcement scope without limitation. Eventually, a design scheme for the bottom reinforcement of the foundation pit based on the simulation calculation results and the force characteristics of Larsen steel sheet piles is proposed, providing guidance and reference for the reinforcement design and construction of the passive zone of similar foundation pits in the Macao region in the future.

Copyright

© 2025 The Author(s)

Open Access

Open Access This chapter is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

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TY  - CONF
AU  - Biao Wu
AU  - Junguang Huang
AU  - Xiaogang Dong
AU  - Kun Chi
PY  - 2025
DA  - 2025/09/22
TI  - Research on the Influence of Reinforcement Width at the Bottom of the Pit on Foundation Pit Deformation and Ground Surface Settlement
BT  - Proceedings of the 2025 International Conference on Resilient City and Safety Engineering (ICRCSE 2025)
PB  - Atlantis Press
SP  - 40
EP  - 52
SN  - 2352-5401
UR  - https://doi.org/10.2991/978-94-6463-856-1_5
DO  - 10.2991/978-94-6463-856-1_5
ID  - Wu2025
ER  -