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直剪试验作为一种常用的室内土工试验,在实践中应用广泛,但是目前在细观尺度上对其剪切带的研究还不多,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,可以较好模拟材料的颗粒属性。因此本文利用PFC数值模拟的方法,首先探讨了颗粒形状、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,而剪切带厚度大约为10.37倍平均粒径。
As a commonly used indoor geotechnical test, direct shear test is widely used in practice. However, there are not many researches on its shear band at the meso-scale at present. This involves the test method and the test equipment. Particle Flow Code (PFC) is the most widely used simulation software. Particle Flow Code (PFC) is based on particles and can simulate the particle properties of materials. Therefore, this paper uses the PFC numerical simulation method, first of all, discusses the particle shape, the initial porosity of the sample on the macro-mechanical behavior of straight shear. Based on the successful establishment of the numerical model of direct shear test of sand, the particle coordination number, particle velocity field and local porosity distribution in the sample were analyzed. It was found that the shear band in the direct shear of sand was not a straight line with perfect level, But has a certain slope and curvature, while the thickness of the shear zone is about 10.37 times the average particle size.