不同颗粒级配对全风化花岗岩回填土抗剪强度的影响

Effect of Different Particle Grading on Shearing Strength of Completely Weathered Granite Backfill Soil

坡面开挖后形成的全风化花岗岩回填土结构松散,物理力学性质差,易受流水侵蚀,导致严重坡面侵蚀。传统治理措施效果有限,土壤改良成为提升土壤抗冲刷能力和改善物理力学性质的有效策略。以全风化花岗岩回填土为主要研究对象,通过室内颗粒分析试验和直剪试验,在不同红黏土和砂粒质量占比条件下进行了系列重塑混合土体的抗剪强度试验研究。结果表明:一般情况下,随着红黏土和砂粒质量占比的增加,不均匀系数和曲率系数整体表现为增大趋势。级配参数对混合土体抗剪强度的影响是通过改变土体中粗细颗粒的比例以及颗粒间的作用关系,来影响其内摩擦角与黏聚力,其中红黏土会增加黏聚力,超过30%质量占比后会降低内摩擦角,而掺入砂粒会增加混合土体的内摩擦角,但是超过18%质量占比后其黏聚力低于回填土。此外,红黏土的掺入可以改善回填土的物理化学性质和肥力条件,并提高土体的抗剪强度,6%质量占比红黏土效果最佳,但实际应用中,可根据需求在6%~30%范围内选择。对于砂粒,在考虑后续工程防护措施下,18%质量占比为较优选择。

Following slope excavation,completely weathered granite backfill soil is created.It has a loose structure,weak mechanical and physical qualities,and is susceptible to water erosion,which can cause significant slope erosion.Traditional treatment methods have a limited impact;thus,improving the physical and mechanical qualities of the soil as well as its anti-scour ability can be accomplished effectively through soil renovation.The completely weathered granite backfill soil was taken as its primary research object.Indoor particle analysis tests and direct shear testing were used to perform a series of shear strength tests of remolded mixed soil under various mass proportions of red clay and sand particle.The results show that the nonuniformity coefficient and curvature coefficient generally rise when the mass proportions of red clay to sand particle increases.Grading parameters have an impact on the internal friction angle and cohesion by altering the ratio of fine to coarse particles in the soil as well as the way those particles interact with one another.This has an impact on the shear strength of mixed soil.Of these,adding sand particle increases the internal friction angle of mixed soil,but its cohesion is lower than that of backfill soil when the mass proportion exceeds 18%.Red clay,on the other hand,boosts cohesion,which reduces the internal friction angle when the mass proportion exceeds 30%.Furthermore,the red clay can enhance the chemical and physical characteristics,fertility levels,and soil shear strength of backfill soil.Although red clay with a mass proportion of 6%offers the best results,it can be chosen from a range of 6%-30%based on the needs in practical application.The ideal choice for sand particle mass proportion,taking into account the precautionary measures of future work,is 18%.