赤泥-粉煤灰改良高含水率粉质土试验研究

Experimental Study on Improved High Moisture Silt by Red Mud and Fly Ash

以安徽五里河高速公路~#13取土场高含水率粉质土为研究对象,采用赤泥、粉煤灰为新型固化剂对其进行固化改良。通过室内试验测试改良土强度、黏聚力和内摩擦角,初步确定固化剂中赤泥与粉煤灰混合比例;通过现场改良土填筑路基试验,测试改良土的含水率、最大干密度、无侧限抗压强度、压实度等指标,综合确定最终固化剂最优掺入比,并确定路基合理碾压次数。结果表明:室内试验测得的固化剂中赤泥与粉煤灰的最优比例关系为1.2∶1;现场试验中,固化改良土在5天内含水率显著降低,固化剂掺入比达6%后对于原状土含水率降低速率贡献并不明显;随固化剂掺入比的增加,现场试验中的改良土无侧限抗压强度显著增加,路基碾压成型效果较好,但固化剂掺入比超过6%后强度提升幅度不大;因此,确定固化剂掺入比6%为最优,同时确定改良粉质土碾压5次为宜。

Taking the silty soil with high moisture content in the #13 soil collection site of Wuli River Expreaaway in Anhui as the research object, red mud and fly ash are used as new curing agents to cure and improve it. The strength, cohesion and internal friction angle of modified soil have been tested by laboratory test which preliminarily determined mixing proportion of red mud and fly ash in curing agent. Through the field test of the improved soil filling subgrade, the indexes such as moisture content, maximum dry density, unconfined compressive strength and compactness of the improved soil have been tested, the optimal incorporation ratio of the final curing agent has been determined comprehensively, and the reasonable rolling times of the subgrade are determined. The results show that the optimal ratio of red mud to fly ash in curing agent measured in laboratory is1.2:1. In the field test, the moisture content of the cured improved soil decreased significantly within 5 days, and the contribution to the moisture content reduction rate of the undisturbed soil is not obvious when the incorporation ratio of curing agent reached 6 %. With the increase of curing agent incorporation ratio, the unconfined compressive strength of the improved soil in the field test increases significantly with a good rolling forming effect of the roadbed. However, when the curing agent incorporation ratio exceeds 6 %, the strength of the improved soil increases very slightly. Therefore, 6 % incorporation ratio of curing agent is the best, and the rolling times of improved silty soil has been determined to be 5 times.