冻融作用下PP纤维–粉煤灰改良黄土抗剪强度试验研究
The Shear Strength Characteristics of PPFiber-Fly Ash Modified Loess under Freeze-Thaw Cycles

通过制备重塑PP纤维–粉煤灰改良黄土试样进行室内直剪试验，探究冻融循环与含水率对改良黄土抗剪强度的影响，并建立改良黄土抗剪强度预估模型。实验结果表明：随着冻融循环次数和含水量增加，改良黄土黏聚力和内摩擦角均呈降低的趋势；冻融循环3次后，黄土内部新的平衡、强度趋于稳定，其中黏聚力降低约47%；随着含水率由13%增至25%，黏聚力降幅达40%，内摩擦角降幅相对较小。基于此，建立考虑冻融循环与含水率影响的PP纤维–粉煤灰改良黄土抗剪强度参数预测模型，为季冻区改良黄土路基工程设计提供参考。
A direct shear test was carried out to study the influence of freeze-thaw cycle and moisture content on the shear strength of modified loess by preparing the samples of remodeled PP fiber-fly ash, and to establish a prediction model for the shear strength of improved loess. The experimental results show that the cohesion and internal friction angle of improved loess decrease with the increase of freeze-thaw cycles and water content. After three freeze-thaw cycles, the new equilibrium and strength of the loess become stable, and the cohesion decreases by about 47%. With the moisture content increased from 13% to 25%, the cohesion decreased by 40%, and the internal friction angle decreased relatively little. Based on this, a prediction model of the shear strength parameters of PP fiber-fly ash improved loess was established considering the influence of the freeze-thaw cycle and water content, which could provide a reference for the design of roadbed engineering of improved loess in seasonal freezing areas.