Investigating impacts of deep foundation pit dewatering on land subsidence based on CFD-DEM method

Abstract

For a deep excavation in sandy cobble stratum, the loss of fine sand particles caused by dewatering generally leads to ground settlement. This paper first analyzed the rules of land subsidence caused by dewatering in the water-rich sandy cobble stratum by dewatering experiments. It is found that even after the groundwater level was restored, the land subsidence basically did not rebound, which shows that the land subsidence is consolidation settlement caused by the loss of fine particles. Then the coupled CFD-DEM numerical model was used to analyze the relationship between the fine particle loss, surface settlement and the grain size of filter media, dewatering rate. On this basis, the rules of land subsidence under the coupling effect of foundation pit dewatering and excavation were further explored by numerical calculation and field measurement. Foundation pit dewatering and excavation in the sandy cobble stratum is the key stage for land subsidence control, As the grain size of the filter media increases, the impact of dewatering on land subsidence gets stronger, therefore, the filter media grain size should be less 8 mm. This study is of great significance to the design of deep foundation pit dewatering in water-rich sandy cobble strata.

Keywords:

• Foundation pit dewatering
• DEM-CFD coupling
• loss of particles
• land subsidence

Acknowledgements

This research was supported by basic research business cost project of Central Public Welfare Research Institute (2018-9020), Science and technology project of CCCC First Highway Engineering Co., Ltd. (4gs (J) - gud-gcl-01-js-016), Shandong Provincial key research and development program (NO.2019JZZY010428), and supercomputing system in Shandong Jianzhu University. The author would like to take this opportunity to gratefully acknowledge the help and supports from the above listed institutions.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data available.

Author contributions

Zhang Xuan contributed significantly to analysis and manuscript preparation; Wang Lihua was dedicated to the collection of field measured data; Wang Hualao was responsible for modelling; Feng Chunlei performed the data analyses and wrote the manuscript; Shi Haojie helped perform the analysis with constructive discussions; Wu Shengzhi contributed to the conception of the study.