Surcharge Load Effect on Additional Ground Settlement of Narrow and Elongated Foundation Pit

Objective In foundation pit engineering, surcharge load acting on the perimeter of the foundation pit (hereinafter referred to as "pit perimeter") will induce additional ground settlement, which exerts a significant impact on the safety of the foundation pit and its surrounding environment. Compared with engineering projects with unrestricted ground conditions around the pit perimeter, the ground settlement trend of foundation pit engineering adjacent to buildings shows a distinct difference. Therefore, it is of great necessity to study the surcharge load impact on the ground settlement trend under spatial effects.

Method By means of the finite element calculation method and combined with parameter sensitivity analysis, the impact of surcharge load adjacent to the foundation pit on foundation pit deformation is investigated. By applying different overload pressures around the foundation pit, the relationship between soil settlement around the pit and surcharge loads is compared and analyzed.

Result & Conclusion  The position and magnitude of the extreme points on the additional ground settlement curve are significantly affected by spatial effects. In the direction perpendicular to the foundation pit, the position of the extreme point X_pm on the additional ground settlement curve has a strong correlation with the surcharge load acting position outside the foundation pit, while the surcharge load pressure has almost no effect on X_pm. As the distance D between the surcharge load position outside the pit and the pit edge increases, the maximum additional ground settlement initially increases and then decreases, exhibiting a "spoon-shaped" trend. Under different surcharge load pressures, the worst-case scenario of additional ground settlement induced by overload is basically located at D=0.5H_e (where H_e is the foundation pit excavation depth). When D/H_e＞2.17, the ground settlement is basically not affected by overload. When the surcharge load position outside the pit is fixed, the relationship between the maximum additional ground settlement and the surcharge load pressure is nonlinear.