浅层土体加固对倾斜桩竖向承载力影响研究

Influence of shallow soil improvement on vertical bearing capacity of inclined piles

桩身倾斜可能导致在小于对应于相同条件下竖直桩的极限承载力的荷载下提前发生弯曲破坏,并可在弯曲破坏前产生较大的桩顶水平位移和桩身挠曲。根据某工程现场载荷试验结果,对倾斜桩桩周土体进行浅层加固数值模拟,以研究其改善倾斜桩竖向承载性状的机理。分析结果表明:加固体深度、加固体面积及加固体尺寸均可对加固效果产生影响。加固体对竖向荷载作用下倾斜桩的承载性状的改善体现在对被动区土体强度和压缩性的改善以及约束桩身上部桩体转动和挠曲的作用。进一步研究了加固体压缩性的影响,结果表明:加固体弹性模量越大,加固效果越明显;但随着弹性模量的增大至一定值后,加固效果基本不再变化。

The inclined pile under vertical load may yield large horizontal displacement, deflection and bending moment. Consequently, bending failure may happen before the ultimate bearing capacity of vertical pile provided by soils is fully mobilized. Based on the field test results, numerical simulations are carried out to analyze the influence of surface soil improvement on the behavior and capacity of inclined piles. The results indicate that the depth, area and location relative to the pile of the treated soil may affect the behavior and failure mechanism of inclined piles under vertical load. The improvement of shallow soils can provide significant lateral support to piles and thus reduce their horizontal displacement. In addition, the treated soils can reduce the rotation and deflection of piles. Both of the two effects can prevent the inclined piles from bending failure before penetration failure happens. Large elastic modulus of the treated soils can better reduce the horizontal displacement, deflection and bending moment of piles under vertical load. However, there is an optimum value, i.e., when the elastic modulus is larger than it, the reinforcement effect no longer increases.