Analysis of deformation in deep excavation support systems considering fluid-structure interaction

WANG Yonghai; LI Wei; LU Shanchao; WANG Risheng; ZHANG Yongzhuang; WU Hongrui; XU Maolin; ZHANG Tao

doi:10.3969/j.issn.1672-0032.2025.04.010

Abstract：To precisely obtain the deformation patterns of retaining and protecting for foundation excavation under the coupling field effects,based on an actual high water head project,finite element software Plaxis is used to conduct finite element simulations of the foundation pit excavation support system under multi-field coupling effects.During the engineering excavation,key deformation indicators such as horizontal displacement of weak links in the support structure,surface settlement,and bottom uplift are monitored in real-time,and the measured results are compared and analyzed with the simulation analysis results.The results show that:1)The maximum horizontal displacement during the foundation pit excavation considering high water head coupling effects occurs about 7.5 m from the top of the pile,with a maximum horizontal displacement of 41.771 mm;The maximum surface settlement is located approximately 5.0 m from the foundation pit,with a maximum settlement of 32.682 mm;The maximum uplift at the bottom of the pit is found in the area between the symmetric center and the pile body,with a maximum uplift of 19.600 mm;The simulated deformation patterns are generally consistent with the field measured data.2)The measured data lie between the numerical simulation results that consider fluid-solid coupling effects and those that do not,and overall,they are closer to the former.3)The maximum simulated results of horizontal displacement of support piles,settlement of surrounding soil,and uplift at the bottom of the pit can serve as warning thresholds for on-site monitoring.As the excavation depth increases in high water head areas,the deformation increases,and timely support should be implemented.