巴东三中滑坡碎石土抗剪强度特征研究

Research on the Shear Strength Characteristics of Gravel Soil of the Slope in No.3 Senior Middle School of Badong County

碎石土是介于土体和岩体之间的一种特殊地质体,引起了国内外众多研究者的重视。结合细粒土室内直剪试验,并在大剪试验下研究了不同粗粒含量(20%、50%、80%)、不同含水率(15%、18%、20%)的碎石土抗剪强度参数的特性。试验结果表明:碎石土抗剪强度参数与碎石土中含水率和粗粒含量有关。含水率对细粒土和碎石土内聚力的影响规律是不同的,碎石土内摩擦角随含水率的增加发生了不同程度的降低;随土体密度的增大,碎石土内聚力升高,随粗粒含量的增加,碎石土内聚力会降低;碎石土内摩擦角随粗粒含量增加先降低后逐渐升高;碎石土τ-σ关系曲线中,随粗粒含量的增加,碎石土剪切强度升高;利用线性逼近的方式近似得到碎石土抗剪强度实用计算公式,通过对比计算值和试验值可知,实用公式计算值在一定程度上能够反映该土样的抗剪强度特征。

Gravel soil is a kind of special geological mass between soil and rock which gains increasingly attention in recent years. Combined with the indoor direct shear test of fine-grained soil, this study investigates characteristics of shear strength parameters of the gravel soil at different gravel content （20%,50% and 80%） and water eontent（15%,18% and 20%） by large-scale direct shear test of gravel soil. The results indicate that shear strength parameters （c,Ф） of the gravel soil are related with the water and gravel content. Water content has different impact on the cohesion rules of the fine-grained soil and gravel soil. Moreover,the internal friction angle Ф of the gravel soil decreases differently with the increase of water content;the cohesion c increases with the increase of soil density and decreases with the increase of gravel content; the internal friction angle Ф decreases first and then increases with the increase of gravel content. According to the τ-σ relationship curves of the gravel soil, the shear strength increases with the increase of gravel content. The practical formula of shear strength is obtained by linear approximation. Comparison of the calculation and experimental values shows that calculation values from the practical formula can reflect the shear strength characteristics of soil samples to a certain extent.