Performance enhancement of large diameter bored pile reinforced by cement-soil in clay under static and cyclic loadings

This paper reports numerical simulation and field test research on the horizontal static and cyclic loading performance of a single pile reinforced by cement-soil. 3D numerical models of soil-cement soil-concrete pile with various reinforcement sizes were established in ABAQUS. By comparing the effects of different cement-soil reinforcement widths and depths on bearing capacity and bending moments, a reinforcement width of 3 times of the pile diameter and a reinforcement depth of 1/4 of embedded depth are the optimal design parameters. On this basis, unidirectional and bidirectional cyclic loading tests were conducted on reinforced and unreinforced piles with a length of 40 m and a diameter of 1.6 m, respectively. The test results indicate that the critical horizontal load of reinforced pile increased by 40%, and the peak bending moment decreased by approximately 14.5% compared to unreinforced pile. This enhancement is attributed to the cement-soil around the pile, which increases the soil resistance and limits the horizontal displacement of the pile head. The cyclic hysteresis curve of reinforced piles is fuller than that of unreinforced piles, exhibiting a larger hysteresis area and a 74.5% increase in the initial stiffness of the pile head. Additionally, the cement-soil surrounding the pile mitigates the effects of cyclic weakening and plastic accumulation under cyclic loading.