压实膨胀土的抗拉强度及拉-剪联合强度公式

Tensile Strength and Tensile-shear Combined Strength Formula for Compacted Expansive Soil

认识并理解抗拉强度以及拉伸-剪切破坏时的强度规律在评估膨胀土边坡稳定性时具有非常重要的意义。通过测试压实膨胀土的抗拉强度和抗剪强度,研究含水率和干密度对抗拉强度的影响规律,以及干密度对抗剪强度的影响规律,综合分析压实膨胀土的强度特性。试验结果表明:抗拉强度随着干密度增加而提高,其增幅为167.3%~195.5%,并可以采用线性函数进行描述;在塑限含水率范围内,增加的含水率能提高压实膨胀土抗拉强度,指数函数能更好地描述这种变化规律;压实膨胀土的抗剪强度随着干密度增加而增加。综合抗拉强度和剪切强度规律发现,线性规律并不能很好地描述剪切强度随着正应力的变化趋势,因此,提出压实膨胀土的考虑拉-剪破坏效应强度公式,经计算值与试验值对比验证,该公式能有效描述压实膨胀土在压剪和拉剪过程中的强度规律。

Understanding the tensile strength and tensile shear strength law is very important in evaluating the stability of expansive soil slope.This paper measures the tensile strength and shear strength of compacted expansive soil to study the effects of water content and dry density on tensile strength and the influence of dry density on the shear strength of compacted expansive soil.Combining the tensile and shear strength of expansive soil,the strength properties of compacted expansive soil are analyze comprehensively.The test result shows that the tensile strength increases by 167.3%~195.5%with the increase of dry density,and can be described by linear function.Within the plastic limit water content,increasing water content could improve the tensile strength of compacted expansive soil,and the exponential function can better address this relationship.Additionally,increasing dry density also enhances the shear strength of compacted expansive soil.The analysis of tensile strength and shear strength indicates that the linear function can’t effectively reflect the change tendency of shear strength with the normal stress.Thus,the strength formula of compacted expansive soil considering the effect of tensile-shear failure is presented.The great consistence between the calculated result and the experimental data demonstrates that the strength formula can address the strength law of compacted expansive soil effectively.