不同水泥土混合桩周围土体的扰动与强度恢复

针对由深层搅拌法或高压旋喷法施工的水泥土混合桩周围土体的扰动与强度恢复的问题，采用两种常用的施工法：高压旋喷混合法（简称旋喷法）和水泥浆搅拌混合法（简称湿法），在日本有明黏土中施工以观测周围土体力学特性的变化。测试结果表明，水泥土混合桩周围土体的扰动程度与其施工方法有关：两种不同施工方法施工后周围土体的当日强度与原状土的强度之比分别是0．42（旋喷法）和0．68（湿法），施工30d后，旋喷法有44％，湿法有40％的初始强度得到恢复。结果亦表明周围土体模量恢复要慢于强度恢复的速度。

Disturbance and strength recovery of surrounding clays around soil-cement columns installed by different mixing methods

For the soil around soil-cement columns, mechanical properties will change after column installation. The strength and modulus changes of the surrounding Ariake marine clays during and after deep mixing using two different installation methods, jet grouting method (JGM) and cement-slurry mixing (CSM) method, are presented. Field construction tests are conducted on Ariake marine clay to investigate the mechanical changes. The Ariake clay is a structured clay and sensitive to disturbance. The investigated results from field and laboratory test indicate that the degrees of disturbance (DOD) to the clays around the soil-cement columns depend on the method of mixing. For the aforementioned two installation methods, the average strength ratio of the surrounding sensitive clay is for JGM method of 0.42 and for CSM method of 0.68. Thirty days after mixing, about 44 % original strength is regained for JGM method and for CSM method, it is 40 %. The recovery of the surrounding soil modulus is slower than that of the strength.