初始含水率和干密度对膨胀土膨胀力影响的试验研究

Experimental study of the influence of initial water content and dry density on the swelling force of expansive soil

不同地区的膨胀土在特定条件下的力学特性具有一定的地域性。试验采用恒体积法测量膨胀土的膨胀力,且用核磁共振技术测量膨胀力稳定后试样的孔隙结构,分析不同初始含水率和干密度对宁明膨胀土膨胀力的影响。结果表明:在中、低干密度状态下,宁明膨胀土的膨胀力随时间的变化呈现快速增长、趋于稳定、缓慢增长、稳定状态4个阶段;在高干密度状态下,宁明膨胀土的膨胀力先快速增长,然后增长速率越来越慢,最终达到稳定状态;用蒸馏水配制土样的初始含水率时,宁明膨胀土的初始含水率越高、干密度越大,配土过程中膨胀能释放越多;孔隙大小直接影响水分子进入土体内部的效率,进而影响膨胀力稳定的时间。

In different regions,the mechanical behaviors of expansive soil are different.The swelling force of Ningming expansive soil was measured by the constant volume method.After the swelling force was stabilized,the pore structure of sample was obtained by nuclear magnetic resonance technique to analyze the influence of different initial water contents and different dry densities on the swelling force of Ningming expansive soil.The research results show that the swelling force of Ningming expansive soil shows four stages of rapid growth,tends to be stable,grows slowly,and reaches a stable state in the two dry density states of medium and low;in the state of high dry density,the swelling force of Ningming expansive soil increases rapidly at first,then the growth rate becomes smaller,and finally the expansive force reaches a stable state;when using distilled water to mix the soil sample,the higher initial water content and the greater dry density of Ningming expansive soil,the more swelling energy released during the mixing process;the efficiency of water molecules entering the soil is influence by soil pore size,and then influence the stability time of the swelling force.