铁尾矿砂改良膨胀土基本工程性质试验研究

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%。

Experimental analysis of the basic engineering properties of expansive soils improved by iron tailings sand

In order to investigate the feasibility and effect of expansive soils improved by industrial waste that iron tailings sand,the basic physical properties and swelling characteristics and unconfined compressive strength of improved soil were study by laboratory test.Besides,by means of SEM,the microstructure of series of samples is studied.The result of test indicated that the marginal moisture content and plasticity index of improved soil decrease with the increase of tailings sand content;free swelling ratio and loaded swelling ratio and swelling pressure also decrease with the increase of tailings sand content.The unconfined compressive strength and cohesion increases with the increase of tailings sand content,but it decreases when tailings sand content more than 30 ％;internal friction angle increase with the increase of tailings sand content.It was found that the structure of improved soil in the most stable state when tailings sand content is 30％ by observing the results of SEM.It is shown that the effect of expansive soils improved by iron tailings sand is obvious.So for the improvement of expansive soils provides a new method.Considering all the indicators,the optimum content of iron tailings sand that improved expansive soils should be 30％.