标准砂直剪试验的PFC数值模拟

PFC numerical simulation of direct shear tests on standard sand

直剪试验作为一种常用的室内土工试验,在实践中得到了广泛的应用,但是目前在细观尺度上对其剪切带的研究还不多,因为这涉及到试验手段和试验仪器方面的问题.PFC(particle flow code)是目前使用较多的模拟软件,其以颗粒为基本单元,可以较好地模拟材料的颗粒属性.因此利用PFC数值模拟的方法,探讨了颗粒形状、试样初始孔隙率对直剪宏观力学行为的影响.在成功建立砂土直剪试验数值模型的基础上,分析了试样内颗粒配位数、颗粒速度场以及局部孔隙率分布,发现砂土直剪中的剪切带并非是完全水平的直线,而是具有一定的斜率和曲率,其剪切带厚度大约为平均粒径的10.37倍.

As a common method of indoor soil test, direct shear test is widely used in practice. However research on its shear band, involving the test method and test apparatus, is insufficient. Particle flow code （PFC） is the most used simulation software, which takes particle as a basic unit, and can be used to simulate the particle properties of the material. Accordingly, the effect of particle shape and initial porosity of the sample on the macro mechanical behavior of the direct shear is studied in numerical simulation using PFC. By successfully establishing a numerical model of direct shear test on sands, the coordination number of the particles, particle velocity field and local porosity distribution is analyzed. The shear band in sands is not a straight line, but a slope and curvature. Thickness of the shear band is about 10.37 times the size of mean particle diameter.