黄河冲(淤)积粉质二灰土的压实特性研究

Compaction properties on Yellow River silty soil stabilized with lime-flyash

试验研究了黄河冲(淤)积粉质二灰土的压实特性。用电子显微镜分析了黄河冲淤积粉质土的微观结构;研究了压实度和压实含水率对二灰土强度的影响;分析了影响压实的关键因素及其影响规律。通过现场试验,提出了合理的施工压实工艺。研究认为,由于水的长距离搬运作用,黄河冲(淤)积粉土颗粒具有高的磨圆度和低的表面强度,加之粉煤灰中球状粉粒的大量存在,碾压时二灰土颗粒间难以形成有效的嵌挤,表现出较差的压实性状;低的压实度和高的碾压含水率使二灰土的强度明显降低;对于黄河冲(淤)积粉质二灰土,土中<0.005 mm的粒级是反映土的填充作用的界限粒级,该粒级和二灰的含量对二灰土的最佳含水率与最大干密度具有显著的影响,而二灰比(1∶4～1∶2)的影响不显著;二灰稳定粉土对振幅和频率是敏感的,高频率强振可使其压实度达到98%。

Through the experiment, the compaction characteristics of Yellow River silty soil stabilized with lime-flyash were studied, and the microstructure of Yellow River silty soil was analyzed with the electronic microscope. The influence of compactness and compaction water ratio to the strength of lime-flyash soil was studied, and the key factors to compaction and the influence were analyzed. The reasonable compaction craft of construction was put forward through the in-situ tests. It was indicated that grain of Yellow River silty soil was of high psephicity and low surface strengths because of the long transport function of the water and a great deal of sphericity silty particle in flyash. It was difficult to form available contact between grains and to be rolled well. The low degree of compaction and the high compaction water ratio could reduce the strength of lime-flyash soil obviously. As for the Yellow River silty soil stabilized with lime-flyash, the grain size of 0.005 mm was the limiting grade that reflected the function of filling. The content of 〈0.005 mm grain and lime-flyash could influenced the optimum water content and the maximum dry density significantly, but the influence of lime-flyash ratio （1 ： 4-1 ： 2） was not obvious. Silt stabilized with lime-flyash was sensitive to amplitude and frequencies of vibration, and high frequency and hard oscillation could attain the degree of compaction of 98%.