桩体模量对水泥土搅拌桩复合地基破坏影响研究

针对目前水泥土搅拌桩复合地基整体稳定性研究主要基于假定全部桩体发生剪切或者弯曲破坏的不足，采用有限差分法，对不同位置处桩体的受力特性，破坏模式以及复合地基整体破坏过程的开展方向进行研究，在此基础上，分析桩体弹性模量对桩体受力、破坏模式和破坏顺序的影响。结果表明：水泥土搅拌桩复合地基在路堤荷载作用下，会同时发生弯曲与剪切2种破坏模式，并且水泥土搅拌桩受力在空间分布上具有很大的不同；路堤荷载作用下，桩体的破坏具有渐进性，坡肩以外桩体更易发生弯曲破坏，破坏方向由坡脚首先发生，并向路堤中心逐渐延伸，而路堤内侧桩体更容易发生剪切破坏，破坏方向由路堤中心向坡脚延伸；随着桩体弹性模量的增加，桩体会由剪切破坏转变为弯曲破坏；低模量水泥土搅拌桩复合地基会首先发生内部剪切破坏，之后坡脚处发生弯曲破坏；高模量水泥土搅拌桩复合地基会先于坡脚处发生弯曲破坏，随后在路堤中心发生剪切破坏；桩体弹性模量的提高会增加桩体抗弯刚度，使其承担更大的弯矩，更容易发生弯曲破坏。

Effect of Column Elasticity Modulus on Composite Foundation Failure of Deep Mixed Columns

Currently, studies on the overall stability of deep mixed columns are mainly based on the assumption that the columns are subjected to shear or bending failure. In this study, a finite difference method was used to determine the stress characteristics of columns in different positions. The failure mode and development direction of the failure process of composite foundations were investigated. Next, the effects of elastic modulus on the stress, failure mode, and failure sequence of the columns were analyzed. The results show that under the action of embankment loads, the composite foundation of deep mixed columns exhibits two failure modes:bending and shearing. The stress of deep mixed columns significantly varies with spatial distribution. Under the action of embankment loads, the column failure is progressive, and the columns beyond the slope shoulder are more prone to bending failure. The failure first occurs at the slope foot and gradually extends to the center of the embankment. However, the columns inside the embankment is more prone to shear failure, and the failure direction extends from the embankment center to the slope foot. As the elastic modulus of the columns increases, the column failure mode changes from shear failure to bending failure. The composite foundation of low-modulus deep mixed columns initially experiences internal shear failure and then, bending failure, at the slope foot. Conversely, the high-modulus deep mixed columns tend to crack before bending at the foot of the slope, and subsequently, shear failure occurs. The increase in the elastic modulus increases the bending rigidity of the columns, causing them to resist more bending moments and become more prone to bending failure.