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研究利用工业废料铁尾矿砂作为添加剂改良膨胀土的可行性与改良效果。通过室内试验,对尾矿砂改良土的基本物理性质指标、膨胀性指标、强度指标以及微观结构进行了研究。试验结果表明,随着掺砂率的增大,试验土样的界限含水率及塑性指数都减小;自由膨胀率、有荷膨胀率和膨胀力等膨胀特性指标随掺砂率的增大均降低。无侧限抗压强度和黏聚力随着掺砂率的增加先增大后减小,在掺砂率为30%时达到最大;内摩擦角随着掺砂率增大而增大。通过观察SEM试验结果,发现在掺砂率为30%时,改良土结构处于最稳定状态,说明掺铁尾矿砂改良膨胀土具有显著效果,为膨胀土改良提供了一种新方法。综合考虑各项指标,认为铁尾矿砂改良膨胀土的最佳掺入比应为30%。
The feasibility and the improvement of the expansive soils using the industrial waste iron tailings as an additive are studied. Through laboratory tests, the basic physical properties index, expansibility index, strength index and microstructure of modified soil of tailing sand were studied. The experimental results show that the limit moisture content and plasticity index of test soil samples decrease with the increase of sand content. Both the expansion indexes such as free expansion rate, load expansion rate and expansion force increase with the increase of sand content reduce. The unconfined compressive strength and cohesion first increased and then decreased with the increase of the sand content, and reached the maximum when the sand content was 30%. The internal friction angle increased with the increase of the sand content. By observing the SEM test results, it is found that the modified soil structure is in the most stable state when the sand content is 30%, which shows that the iron-doped tailings sand has the remarkable effect of improving the expansive soil and provides a new method for the improvement of the expansive soil. Taking all the indicators into consideration, it is considered that the optimum incorporation ratio of iron tailings to expansive soils should be 30%.