Study on Disturbance Mechanism of Squeezed and Non-Squeezed Soil Piles on Soft Soil Foundation

Abstract

The construction process of pile foundations can significantly disrupt the soil. Therefore, it is necessary to limit the degree of soil disturbance caused by pile foundation construction to an acceptable level. This paper examines the disturbance effects of pile driving on soft soil foundations, specifically analyzing the squeezing effect of squeezed soil piles and the unloading effect of non-squeezed soil piles. To investigate these effects, two typical squeezed soil piles, a hydrostatic pile, and a bag grouting pile, as well as a typical non-squeezed soil pile (a bored pile) are selected. Specifically, a novel construction method for numerical models, which simulates the mechanical processes of different pile types under standard grids, is proposed. Three crucial indicators—soil displacement field, stress field, and disturbance influence range—are chosen to compare the disturbance effects of three types of piles on the soil. Results indicate that the two types of squeezed soil piles cause significant disturbance to the soil displacement field, especially in the horizontal direction, while causing a relatively slight disturbance to the soil stress field. Among the two of them, the disturbance magnitude and range of the hydrostatic pile are greater than those of the bag grouting pile. For the non-squeezed soil pile, the soil displacement field changes minimally and the stress field remains basically unchanged during the pile driving process of the bored pile. To compare and quantify the disturbance effects of three types of piles on soil, the soil disturbance range in the horizontal direction of each pile is normalized by its radius. Results indicate that the horizontal disturbance values of maximum horizontal stress for all three types of piles are approximately 1/5 of the pile length above the pile tip, with normalized values of 7.6, 5.5, and 3.5, respectively. The maximum horizontal deformation disturbance range in the horizontal direction occurs near the ground surface and has normalized values of 15.2, 7.5, and 1.1 for the three types of piles, respectively. Therefore, the hydrostatic pile has the greatest disturbance effect, followed by the bag grouting pile and the bored pile. However, within the allowable range of disturbance in practical engineering, the optimal piling method can be selected by comprehensively considering factors such as the construction difficulty and economic costs.