高压旋喷桩桩周土的变形和渗透特性研究

Deformation and Permeability Characteristics of Soil around High Pressure Jet Grouting Pile

摘要: 桩周土的渗透系数和固结变形对桩侧摩阻力的发挥起着重要的作用。为了测试距高压旋喷桩不同桩距和深度下的试样压缩回弹特性、渗透特性及其与矿物成分之间的关系，对其试样进行了固结试验和X衍射试验(XRD)。利用时间平方根方法计算固结试验中每一级荷载下的固结系数，再利用太沙基一维固结理论计算软黏土的渗透系数。试验结果研究表明：软黏土屈服后，远桩土与桩间土的压缩曲线近似平行，5 m、15 m处的远桩土的压缩指数和回弹指数稍微大于桩间土的压缩指数。在双对数坐标下，渗透系数随压缩应力的增大而减小；渗透系数随孔隙比减小而减小，且二者间呈线性关系；与试样的初始孔隙比、应力路径无关。塑限、液限随黏土矿物成分的增加而增大，渗透系数反之。

Abstract: The permeability coefficient and consolidation deformation of the soil around the pile play an important role in the play of the lateral frictional resistance of the pile. In order to test the compressive rebound properties, permeability properties and their relationship with mineral composition of the specimens at different pile spacing and depths from the high-pressure rotary piles, consolidation tests and X diffraction tests (XRD) were performed on their specimens. The time square root method is used to calculate the consolidation coefficient by conducting series of one-dimension compression test, and the permeability coefficient of soft clay can be calculated by the Terzaghi’s one-dimensional consolidation theory. The experimental results show that the compression curves of the far pile soil and the soil between piles are approximately parallel after the soft clay yield. The compression index and rebound index of the far pile soil at 5 m and 15 m are slightly larger than those of the soil between piles. In double logarithmic coordinates, the permeability coefficient decreases with the increase of compressive stress. The permeability coefficient decreases with the decrease of void ratio, and there is a linear relationship between them. It is independent of the initial void ratio and stress path of the specimen. The plastic limit and liquid limit increase with the increase of clay mineral composition, and the permeability coefficient inversely.