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采用针孔试验、碎块试验和单轴拉伸试验,研究分散性土改性剂对土的分散性和抗拉强度的影响。分散性土改性剂由氯化铝、三氯乙酸和聚丙烯酰胺等材料组成,其中氯化铝和三氯乙酸可改善化学性分散性土,而聚丙烯酰胺可改善物理性分散性土。试验表明:随着改性剂含量的增加,土的分散性降低,抗拉强度提高。对于化学性分散性土,氯化铝质量分数≥0.3%时,土样由分散性土转变为非分散性土;随着氯化铝含量的增加,抗拉强度增加幅度逐渐变缓;三氯乙酸质量分数≥0.9%时,土样由分散性土转变为非分散性土;在三氯乙酸质量分数为0.9%时,土体抗拉强度达到最大值。对于物理性分散性土,聚丙烯酰胺质量分数≥0.2%时,土样由分散性土转变为非分散性土。研究表明:分散性土改性剂不仅可有效改善土的分散性,而且土的抗拉强度可提高30%~70%;分散性土改性剂的作用机制主要在于通过改性剂与土体发生一系列物理化学反应,氯化铝通过降低土体的碱性和增加土体中高价阳离子的含量而达到改性化学性分散性土的目的;三氯乙酸通过降低土体的碱性而减少化学性分散性土的分散特性;聚丙烯酰胺掺入土体可促进团粒结构的形成,提高物理性分散性土的抗冲蚀性。此外,随着含水率的增加和压实度的降低,土的抗拉强度降低。
Pinhole test, fragment test and uniaxial tensile test were used to study the influence of disperse soil modifier on soil dispersibility and tensile strength. Dispersing soil modifiers consist of materials such as aluminum chloride, trichloroacetic acid, and polyacrylamide, of which aluminum chloride and trichloroacetic acid improve chemically dispersible soils and polyacrylamide improves physically dispersible soils. Experiments show that: with the increase of modifier content, soil dispersibility decreases, tensile strength increases. For the chemical dispersible soil, the mass fraction of aluminum chloride ≥0.3%, soil samples from disperse soil into non-dispersive soil; with the increase of aluminum chloride content, the increase of tensile strength gradually becomes slow; trichloro When the mass fraction of acetic acid≥0.9%, the soil samples changed from dispersive soil to undispersed soil. When the content of trichloroacetic acid was 0.9%, the soil tensile strength reached the maximum. For physically disperse soil, when the mass fraction of polyacrylamide is ≥0.2%, the soil sample is changed from disperse soil to undispersed soil. The results show that the dispersant soil modifier can not only effectively improve the dispersibility of soil, but also increase the tensile strength of soil by 30% -70%. The mechanism of dispersant soil modifier mainly lies in that the modifier disperses with soil Series of physical and chemical reactions, aluminum chloride by reducing the alkaline soil and increasing the content of high-priced cation in the soil to achieve the purpose of modified chemical dispersible soil; trichloroacetic acid by reducing the alkaline soil to reduce chemical Disperse soil dispersion characteristics; polyacrylamide incorporation into the soil can promote the formation of aggregate structure, improve the physical dispersion of soil erosion resistance. In addition, the soil tensile strength decreases as the moisture content increases and the degree of compaction decreases.