风化砂不同掺入率对膨胀土特性影响的研究

RESEARCH ON THE INFLUENCE ON EXPANSIVE SOIL CHARACTERISTICS BY DIFFERENT MIXING RATES OF WEATHERED SAND

针对目前膨胀土改良措施中存在的问题,提出了一种新的改良方法——在膨胀土中掺入风化砂,对膨胀土实施物理改良。对风化砂不同掺入率的膨胀土进行颗分试验,液、塑限试验,活性指数试验,相对密度试验。试验表明:随着掺砂比例的增大,活性指数急剧下降,液性指数发生了降低;对风化砂不同掺入率改良膨胀土进行的自由膨胀率、有荷膨胀率、无荷膨胀率和膨胀力试验表明,随着掺砂比例的增加,膨胀土的膨胀性得到显著的抑制;最后对掺砂膨胀土进行了直剪试验、无侧限抗压强度试验、CBR试验和回弹模量试验,探讨不同掺砂率对强度指标的影响及其变化规律。试验研究结果表明,掺砂能较好地改良膨胀土的基本工程性质指标,有效抑制膨胀土的膨胀特性,改善膨胀土的力学强度性能,掺砂后膨胀土的各项指标均可达到路基填料的要求。

Based on defects of expansive soil modification methods,a physical improvement method with which weathered fine sand was mixed with expansive soil was proposed.Grain size distribution test,liquid limit and plastic limit test,activity index test and specific gravity test of different proportions of weathered sand modified expansive soil were done.Experiments results showed that with the increase in the proportion of sand,activity index fell sharply and liquid limit and plastic limit were changed significantly.Free swelling ratio test,loaded swelling ratio test,swelling ratio test and expansive force test of different proportions of weathered sand modified expansive soil were done.With the increase in the proportion of sand,expansive characteristics of expansive soil were significantly inhibited.At last,direct shear test,unconfined compressive strength test,CBR test and modulus of resilience test of different proportions of weathered sand modified expansive soil were done.The laws and influence of different proportions of weathered sand modified expansive soil were discussed.Test results indicated that sand could better improve expansive soil engineering characteristic indexes,effectively inhibit expansive characteristic of expansive soil,improve the mechanical strength of expansive soil.Each index of weathered sand modified expansive soil could meet roadbed filling requirements.