粉煤灰-天然砂改良膨胀土强度特性试验研究

Strength Characteristics of Modified Expansive Soil with Fly Ash and Weathered Sand

为探讨粉煤灰-天然砂改良膨胀土强度特性,对改良膨胀土进行了击实试验、无侧限抗压试验和三轴试验。试验结果表明:粉煤灰掺量一定时,最大干密度随天然砂掺量增加呈先增大后减小趋势,而最优含水量逐步减少;天然砂掺量一定时,最大干密度及最优含水量随粉煤灰掺量增加均逐渐减小;在粉煤灰和天然砂之和占比20%不变条件下,随天然砂占比减小,无侧限抗压强度与三轴抗剪强度先增大后减小,天然砂掺量5%和粉煤灰掺量15%时强度最大;随着粉煤灰和天然砂掺量的增加,内摩擦角先增加后减小;粉煤灰和天然砂掺量之和一定时,随着粉煤灰的增加和天然砂掺量的减少,黏聚力逐渐减小。研究成果可供致力于改良膨胀土工程性质的研究人员参考。

Compaction test,unconfined compression test and triaxial test were carried out to study the strength characteristics of expansive soil modified by fly ash and weathered sand composite material.Results demonstrated that when keeping fly ash dosage unchanged,increasing the content of weathered sand enhanced the maximum dry density at first but then weakened,while gradually lessened the optimum water content;when keeping the content of weathered sand unchanged,increasing the fly ash dosage deteriorated both the maximum dry density and the optimum water content.When the proportion of fly ash and weather sand together remains at 20%,with the climbing of weathered sand proportion,the unconfined compressive strength and triaxial shear strength of expansive soil augmented firstly and then declined.The strength of expansive soil reached the maximum when weathered sand proportion was 5%and fly ash proportion 20%.In addition,the influences of fly ash and weathered sand dosages on the internal friction angle and cohesion of expansive soil were also examined.Internal friction angle inceased but then reduced with the rising of fly ash and weathered sand content;when the sum of fly ash and weathered sand content reamained unchanged,cohesion developed in negative relation with fly ash content,and in positive relation with weathered sand content.