土壤稳定剂-聚丙烯纤维复合改良膨胀土的试验研究

针对常规单一方法改性膨胀土效果不佳的问题，利用土壤稳定剂及聚丙烯纤维复合改良膨胀土物理力学特性，抑制内部裂隙扩展。基于自由膨胀率、水稳试验、无侧限抗压强度试验获得单掺土壤稳定剂的最优稀释比及单掺聚丙烯纤维的最佳纤维掺量。同时在干湿循环条件下，基于宏观力学强度试验及细观裂隙、微观孔隙观察，分析土壤稳定剂-聚丙烯纤维复合改良膨胀土的效果。研究表明:土壤稳定剂可有效降低膨胀土的自由膨胀率，增强膨胀土的水稳性，改性膨胀土的最优稀释比为1∶150（体积比）；聚丙烯纤维的加筋作用能有效提高膨胀土的无侧限抗压强度，且最佳纤维掺量为0.20%（质量比）；聚丙烯纤维与土壤稳定剂共同发挥作用，复合改良膨胀土后能有效提高土体的无侧限抗压强度，且强度衰减速率得到抑制，膨胀土细、微观裂隙扩展速率得到有效控制。本研究可为土壤稳定剂及聚丙烯纤维复合改良膨胀土的工程应用提供参考。

Experimental study on improving expansive soil with soil stabilizer-polypropylene fiber composite

In response to the problem of poor effect of conventional single-method modification of expansive soil, this research team selected soil stabilizer and polypropylene fibers to improve the physical and mechanical properties of expansive soil and inhibit the expansion of internal fissures. The optimal dilution ratio of single-doped soil stabilizer and the optimal fiber dose of single-doped polypropylene fibers were obtained based on the free swelling rate, water stability test and unconfined compressive strength test. Meanwhile, the effect of soil stabilizer-polypropylene fibers composite improvement of expansive soil was analyzed under wet-dry cycling conditions based on macroscopic mechanical strength experiments and fine fracture and microscopic pore observation. From the experimental results, it can be obtained that the soil stabilizer can effectively reduce the free swelling rate of the expansive soil and enhance the water stability of the expansive soil, and the optimal dilution ratio (volume ratio) of the modified expansive soil is 1∶150. The reinforcing effect of polypropylene fibers can effectively improve the lateral limitless compressive strength of expanded soil, and the optimal fiber admixture is 0.20% (mass ratio). Polypropylene fibers and soil stabilizer can work together, and the unconfined compressive strength of the composite soil is effectively increased and the rate of strength decay is suppressed, and the expansion rate of fine and microscopic fractures of expanded soil is also effectively controlled. This study can provide reference for engineering application of soil stabilizer and polypropylene fiber composite to improve expansive soil.