粉煤灰改良膨胀土抗剪强度室内试验研究

以宜昌市某公路沿线的膨胀土为原材料,采用宜昌热电厂产生的粉煤灰为外掺剂,在室内进行直接剪切试验,观察不同掺灰量对改良膨胀土的抗剪强度指标的影响规律.研究结果表明,掺粉煤灰改良膨胀土能提高膨胀土的抗剪强度,掺入粉煤灰之后,内摩擦角增大,黏聚力降低.掺粉煤灰改良膨胀土提高膨胀土的抗剪强度主要靠提高内摩擦角来实现.随着掺入粉煤灰量的增加,改良膨胀土的内摩擦角先增大后减小,当掺灰量达14％时,内摩擦角达到最大值.随着掺人粉煤灰量的增加,改良膨胀土的黏聚力逐渐降低,降低的趋势先快后慢.随着掺入粉煤灰量的增加,改良膨胀土的抗剪强度先增大后减小,当掺灰量达到14％时,抗剪强度达到最大值.结论为：掺灰量达14％时,改良效果最好.

ExperimentAl Study on SheAr Strength of ExpAnsive Soil Improved by Fly Ash

In order to study the mechanism of fly ash modified expansive soil, expansive soil along the Yichang creek tower to crow magpie highway as raw material, produced by Yichang thermal power plant fly ash as admix- ture, the direct shear test in laboratory, this paper analyzes the influence of different lime content of modified ex- pansive soil the index of shear strength and the influence rule. The results show that soil can improve the shear strength of expansive admixture of fly ash modified, after the incorporation of fly ash, the internal friction angle in- creases, the cohesion decreases. Soil to improve the shear strength of the expansive soil mainly depends on the an- gle of internal friction to achieve the expansion of fly ash modified. With the increase of fly ash content, improved expansive soil internal friction angle increases first and then decreases, when mixed with ash 14% , internal friction angle reaches a maximum value. With the increase of fly ash content, improved expansive soil cohesion decreases, decreases soon after the first slow. With the increase of fly ash content, improved the shear strength of the expan- sive soil first increases and then decreases, when mixed with ash reaches 14% , the shear strength reaches a maxi- mum value. The incorporation of 14% and the improvement effect of it is the best.