考虑颗粒破碎的粗粒土直剪试验离散元模拟

摘要

为了分析粗粒土的剪切力学特性，采用离散元软件PFC2 D模拟考虑颗粒破碎的粗粒土直剪试验，提供了制备可发生破碎的单颗粒粗粒土试样方法，以及改变离散元试样孔隙率的方法。在不同竖向压力作用下对粗粒土试样模拟直剪试验，分析剪应力、体应变与剪切位移的关系，剪切前后应力状态，剪切后速度分布情况。改变粗粒土试样的孔隙率和颗粒间黏聚力，分析粗粒土剪切强度的影响因素。研究表明，试样先剪缩再剪胀，剪应力峰值、残余强度随着竖向压力的增大而增大。应力场受剪前均匀分布，受剪后分布不均匀。剪切带内外颗粒处于不同的运动状态，剪切带内速度变化梯度较大。在相同竖向压力作用下，剪切强度随孔隙率增大而减小，随黏聚力增大而增大。%In order to analyze the shear behavior of coarse-grained soil, the discrete elements software PFC2D is used to simulate the direct shear test on coarse-grained soil considering particle crushing.The methods of preparing the crushable coarse-grained soil sample and changing the porosity of the sample are introduced.The direct shear tests are simulated under different vertical pressure, and analyze the relationship between shear stress and shear dis-placement, the relationship between volume strain and shear displacement, the stress state before and after the test and the velocity distribution after the test.The porosity and contact-bonded force are changed to analyze the factors affecting the shear strength of coarse-grained soil.The study shows that shear dilatation occurred after shear con-traction in the test.The peak shear strength and residue strength increases with the vertical pressure increasing.The homogeneous distribution stress field before the test changes into the inhomogeneous distribution after the test.The particles in the shear band are in different motion state, and the gradient of velocity is large.Under the same vertical pressure, the shear strength decreases with the porosity increasing and increases with the contact-bonded force increasing.