复合改良粉砂土性能实验研究

Experimental Study on Properties of Compositely Improved Silty Sand

为了探究水泥、粉煤灰、石灰三掺料改良粉砂土路基填料的工程特性,采用静力性能实验、毛细水上升实验、动三轴实验相结合的方法,揭示粉砂土掺入改良剂前后静态指标与毛细水上升高度的变化.分析了水泥掺量6%、粉煤灰掺量2%和石灰掺量7%改良粉砂土作为路堤填料,在各工况下累积动应变曲线特征.研究结果表明:粉砂土改良后,内摩擦角增加了约25%、黏聚力提升约50倍、28 d无侧限抗压强度提高约8.6倍;改良土毛细水上升高度比天然土降低约89%;含水率对土体累积动应变发展影响较大,含水率过高时黏聚力损失应变增加更为明显;围压和压实度增加使改良土体强度增加,土体累积动应变发展速率变小;振动频率增大改良土体的累积动应变发展速率降低;拟合了理想填筑状态不同路基深度土体累积动应变曲线关系式.

In order to explore the engineering characteristics of silty sand subgrade filler improved by cement,fly ash and lime,the combination of static performance test,capillary water rise test and dynamic triaxial test was used to reveal the changes of static index and capillary water rise height of silty sand before and after adding modifier.The characteristics of cumulative dynamic strain curves of improved silty sand subgrade with cement content of 6%,fly ash content of 2%and lime content of 7%under various working conditions were analyzed.The results show that the internal friction angle of improved silty sand increases by about 25%,the cohesion increases by about 50 times,and the unconfined compressive strength at 28 d increases by about 8.6 times.The capillary water rising height of improved soil is about 89%lower than that of natural soil.The water content has a great influence on the development of cumulative dynamic strain of improved soil.When the water content is too high,the cohesion loss strain increases more obviously.With the increase of confining pressure and compactness,the strength of improved soil increases and the development rate of cumulative dynamic strain decreases.The development rate of cumulative dynamic strain decreases with the increase of vibration frequency.The cumulative dynamic strain curves of soil at different subgrade depths in ideal filling state were fitted.