直接加固软弱下卧土层的地基工作性状模型试验研究

Model test research on working behaviour of foundation reinforcing directly underlaid weak soil layers

高压喷射注浆法可以在软弱下卧土层中直接形成加固桩体对软土地基进行加固。对这种加固方法形成的地基进行了一组模型试验,其中包含了天然地基和加固地基,加固地基中设置了一组3×3的加固桩体,通过对比研究了直接加固软弱下卧土层的地基处理方法对地基工作性状的影响。结果表明:直接加固软弱下卧土层的方法能很好地改善地基的沉降特性,提高地基的承载能力。加固桩体能有效地传递荷载,使加固区软弱土体的压缩量大大减小。随着荷载的增加,加固桩体顶端承担的荷载大体呈线性增加,桩顶轴力表现为角桩最大,边桩次之,中心桩最小。加固桩体上部受负摩阻力作用,下部受正摩阻力作用,桩身最大轴力位于距桩顶25 cm处。加固区的平均桩-土应力比随荷载的增加而减小。

High pressure jet grouting can directly reinforce weak soil layers of soft soil foundations. In order to investigate the reinforcing functions of the direct reinforcement of weak soil layers to foundations, a group of model tests of natural foundations on weak soil layers and reinforced foundation is performed in comparison. In order to form reinforced foundation, a group of 3 × 3 piles is set in the weak soil layers.Test results show that direct reinforcement method of weak soil layers can greatly improve foundational settlement characteristics and bearing capacity. Upon reinforcement, piles are noted for good transfer loads, greatly reducing the compression of weak soil layers. Pile top load increases linearly with the increase of applied loads, and top loads of comer piles are the biggest, that ones of side piles are second, and that ones of center piles are smallest. Upper part of piles are subjected to negative friction, lower part of piles are subjected to positive friction, and the maximum axial force for pile is located 25 cm from the pile top. The average pile-soil stress ratio of reinforced area decreases with load increasing.