初始含水率对风化砂改良膨胀土膨胀力影响

膨胀力是反应膨胀潜势的重要指标之一,选取湖北宜昌小溪塔至鸦鹊岭一级公路改建工程K25+000段膨胀土,对其进行掺风化砂改良处理,在对不同风化砂掺量下的膨胀土进行基本胀缩试验的同时,深入探究了初始含水率对风化砂改良膨胀土膨胀力的大小以及增长速度的影响.试验研究结果表明,掺入风化砂后,膨胀土的各项胀缩指标均有明显改善,且均能达到路基填料的标准;在同一风化砂掺量下,随着初始含水率的增加膨胀力逐渐降低,且膨胀力可以用初始含水率的幂函数很好地描述,两者相关性较好;初始含水率越低土样所具有的的膨胀潜势及膨胀力越大,膨胀力随时间的变化曲线越陡,浸水后改良膨胀土的膨胀力的增长主要集中在1h以内,稳定速度较快;综合考虑经济性以及初始含水率和风化砂掺量对膨胀力大小的影响,建议将风化砂掺量控制在30%~40%,初始含水率控制在略大于最佳含水率1%~2%内,此时对膨胀力的抑制效果较好.

Research on the influence of initial moisture content on expansive force of weathered sand improved expansive soil

Expansive force is one of the important indicators of expansion potential responses. This paper se- lects the expansive soil of K25 ＋ 000 section from Xiaoxita to Yaqueling first-class highway rebuilding engi- neering, mixing weathered sand to improve expansive soil. The basic swell-shrink experiment is carried out under different weathered sand contents, at the same time, deeply research on the influence of an initial mois- ture content on the growth speed and the size of the expansive force of weathered sand improved expansive soil. The test results show that： after incorporating weathered sand, the swell-shrink indicators of expansive soil are obviously improved and can reach the standards of subgrade filling; when incorporating the same weathered sand dosage, with the increasing of an initial moisture content, the expansive force is reduced grad- ually. The expansive force can use the power function of an initial moisture content to describe the correlation. The lower the initial moisture content, the greater the potential and the expansive force of the soil samples.The curve of the expansive force changing with time is steep. After flooding, the growth of the expansive force of the improved expansive soil is concentrated within one hour, and the speed of steady is faster. The compre- hensive consideration for the influence of economy and the initial moisture content and weathered sand dosage on expansive force, the weathered sand dosage should be controlled between 30% and 40% , and the initial moisture content is controlled in a slightly larger than the best moisture content of 1% and 2%. At this time, the inhibition effect of expansive force is better.