干湿循环作用下铁尾矿砂水泥土强度劣化规律

Experimental Study on Strength Deterioration Law of Cement Soil Mixed with Iron Ore Tailings under Wetting-Drying Cycles

为了探讨铁尾矿砂水泥土的力学性能及抗干湿循环劣化能力,通过无侧限抗压强度试验和干湿循环试验,研究水泥掺量、铁尾矿砂掺量及干湿循环次数对铁尾矿砂水泥土强度的影响。试验结果表明:铁尾矿砂在20%掺量下对水泥土的强度提升最大,在40%掺量下对水泥土的强度提升最小,最高强度增长率约为70%;干湿循环对素水泥土和铁尾矿砂水泥土的强度造成的损伤程度不同,素水泥土在循环初期强度损失较大而在循环后期损失较小且逐渐趋于平缓,铁尾矿砂水泥土在循环初期强度损失较小,超过一定循环次数后强度下降明显;水泥土强度劣化的主要原因是孔隙水的干缩湿涨造成水泥土内部的应力集中。

In order to explore the mechanical properties and anti-deterioration ability of iron tailings cement soil,we conducted unconfined compressive strength test and wetting-drying cycle test to examine the influences of cement content,iron tailing sand content and number of drying and wetting cycles on the strength of iron tailings cement soil.Results demonstrated that a dosage of 20%iron tailing sand had a largest improvement effect on the strength of cement soil,improving by about 70%;a dosage of 40%iron tailing sand had a least enhancement effect.Dry-wet cycles had deterioration effects of varied levels on the strengths of plain cement soil and iron tailings cement soil:the strength loss of plain soil-cement was greater at the initial stage of cycle than that in the later stage and tended to be gentle gradually,while the strength loss of iron tailings cement-soil was small at the initial stage of cycle,and the strength deteriorated obviously after a certain number of cycles.The main reason for the deterioration of cement-soil strength is the stress concentration caused by the drying shrinkage and wetting swelling of pores.