冻融循环作用下水泥+磷石膏改良湿陷性黄土力学特性试验

Experimental Study on Mechanical Properties of Collapsible Loess Improved by Cement and Phosphogypsum under Freeze-thaw Cycles

利用水泥+磷石膏复合材料对湿陷性黄土进行固化改良,并进行不同冻融循环次数下的力学性能研究,分别探索冻融循环作用下磷石膏-水泥改良湿陷性黄土的强度特征、渗透特性、水稳定性以及动力(抗震)特性。结果表明:随着磷石膏掺量的增加,改良黄土的抗压强度、水稳系数和临界动应力均呈先增加后减小的变化特征,渗透系数则表现为先减小后增大,且磷石膏的最佳掺量为2%;随着冻融循环次数的增加,改良黄土的抗压强度、水稳系数和临界动应力均呈逐渐减小的变化趋势,而渗透系数则表现为先略微减小,后逐渐增大的变化特征;根据试验成果,得到水泥-磷石膏改良黄土路基的动应力衰减系数取值范围为0.55~0.75。相关研究成果可为湿陷性黄土的改良提供新的方向,同时也可以促进和提升磷石膏的综合利用率,具有一定的社会、经济和环境效益。

The collapsible loess was solidified and improved by cement+phosphogypsum composite material in the paper,and the mechanical behavior of the collapsible loess was studied under different freeze-thaw cycles.The strength characteristics,permeability characteristics,water stability and dynamic characteristics of the collapsible loess improved by phosphogypsum cement under freeze-thaw cycles were discussed respectively.The results showed that with the increase of phosphogypsum content,the compression resistance of the improved loess was improved with the increase of freeze-thaw cycles,the compressive strength,water stability coefficient and critical dynamic stress of the improved loess decreased gradually,However,the permeability coefficient showed a change characteristic of slighthy decreasing first and gradually increasing later.According to the test results,the value range of dynamic stress attenuation coefficient of cement phosphogypsum improved loess subgrade is0.55~0.75.The relevant research results can provide a new direction for the improvement of collapsible loess,but also can promote and enhance the comprehensive utilization of phosphogypsum,which has certain social,economic and environmental benefits.