风化砂改良膨胀土对抗剪强度指标的影响研究

Research on Shear Strength Index of Expansive Soil Modified by Weathered Sand

通过对比分析石灰、水泥、粉煤灰改良膨胀土对抗剪强度指标的影响,引入风化砂改良膨胀土对抗剪强度指标影响的研究。在膨胀土中掺入不同比例的风化砂,进行了直剪试验。结果表明:掺入风化砂能有效提高膨胀土的抗剪强度;粘聚力随着掺砂比例的增加而逐渐减小,内摩擦角则随着掺砂比例的增加先增大后减小。改变掺砂膨胀土的含水率,进行直剪试验,结果得出:同一掺砂比例下的粘聚力与内摩擦角均随着含水率的增加先增大后减小。掺入不同比例风化砂进行胀缩特性试验得出:掺风化砂能有效抑制膨胀土的膨胀性和收缩性,改良后的胀缩总率低于0.7%,能达到路基填料的标准。综合考虑掺砂比例和含水率对膨胀土抗剪强度指标的影响,可以得出:当掺砂比例为30%、含水率为10%时,掺砂膨胀土的抗剪强度指标达到最佳值。

Through the comparative analysis of the influences of expansive soils improved by lime, cement, coal ash on the shear strength index, impact of the weathered sand improved expansive soil on shear strength index was studied. The shear of the expansive soil mixing with different proportion of weathered sand was tested. The results showed that the expansive soil shear strength could be effectively improved after weathered sand was incorporated into expansive soil~ its cohesive force will decrease gradually with the increase of sand addition proportion; and the angle of internal friction would firstly increased and then decreased along with the in- crease of sand addition proportion. The expansion characteristic was tested after adding different proportion of weathered sand, and the conclusion could be drawn as followings, blending weathered sand could effectively inhibit the expansion and contraction of expansive soil, the swell-shrink rate of the improved expansion soil was lower than 0.7%, therefore, it could reach the standard of packing filling. With respect to compre-hensive consideration of the influence of the sand addition ratio and moisture content on expansive soil shear