强膨胀土自然膨胀特性的试验研究

Experimental study on humidification deformation of expansive soil

以邯郸强膨胀土为研究对象,采用改进的三联高压固结仪,对膨胀力、自然膨胀力和自然膨胀率等进行研究.结果表明:在相同初始含水率条件下,随干密度的增大膨胀力呈指数增长;在相同干密度条件下,随初始含水率增大,膨胀力先增大后减小,在最优含水率附近出现峰值;随含水率增量的增加自然膨胀力呈对数增长,且在初期受含水率增量的影响更大;无荷和有荷自然膨胀率随含水率增量的变化均可分为快速线性增长与慢速线性增长两个阶段;当初始含水率和干密度相同时,在慢速线性增长阶段,无荷增湿膨胀率斜率与有荷增湿膨胀率斜率之比随竖向应力近似呈对数减小;强膨胀土增湿膨胀的自然膨胀力、自然膨胀率的变化规律与蒙脱石水化和增湿致孔隙充填的自由水量有关.

Volumetric behavior of expansive soil during wetting to saturation was investigated by means of high pressure oedometer.Test results indicate that,under the same initial moisture content,the swelling pressure exponentially increases with increasing dry density.With the same dry density,swelling pressure increases first and then decreases with initial water content,and the maximum swelling stress is reached when moisture content approximately reach the optimal moisture content.The nature swelling pressure increases logarithmically with increasing water content.The swelling rate test results can be divided into two stages:the initial linear fast growing stage and the subsequent lower speed linear growing stage.The regression formulas under unloaded and loaded conditions are derived separately with the same initial moisture content and dry density in the second stage,and the swelling pressure and swelling ratio are related to the amount of water participating in montmorillonite hydration and pore filling.