圆砾土大型三轴试验力学特性研究

Research on Mechanical Characteristics of Gravel Soil Based on Large-Scale Triaxial Tests

采用大型三轴压缩试验对各级围压下南宁地区两种常见的不同密实度圆砾土的抗剪强度、变形特性、内摩擦角等进行了分析比较,试验结果表明在中密状态下圆砾土表现出明显的应变硬化和剪缩特性,而在密实状态下圆砾土则表现出应变软化及剪胀特性,抗剪强度包络线由于圆砾土本身的颗粒形状特性以及围压的增大导致剪胀作用减弱呈近似的线性,随着密实度的增大,圆砾土的抗剪强度增大,内摩擦角增大,试验值相较南宁地区以往所取的经验值而言有较为明显的提高,有效地减小了实际工程中围护结构的受力及变形,为南宁地区工程设计的参数优化起到了一定的指导作用。

The shear strength, deformation characteristics and internal friction angle of gravel soil, which is common in Nanning, under different confining pressure and density are compared by conducting a large-scale triaxial test. The test results show that under medium density the main stress-strain deformation behaves as strain-hardening and shrink, while under high density it behaves as strain-softening and dilation. The Mohr-Coulomb envelopes are approximately linear as a result of the shape effect of particle in gravel soil and the weakening of dilation when the confining pressure is increased. The increasing of density resuhs in the increase of strength and internal friction angle. The test value is apparently increased when compared to the empirical value used in Nanning before. It effectively decrea- ses the stress and deformation of the support structure which plays a guiding role in parameter optimization of engineering design in Nanning.