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为分析砂土在复杂应力条件下的剪切力学特性,采用商业离散元软件PFC3D对单粒组中密砂的空心扭剪试验进行了仿真模拟,分析了数值试样的应力-应变关系,研究了不同剪切方向下离散介质的强度、体积应变特性以及中主应力比对它们的影响,再现了力链在加载过程中的演化,并对剪切带的倾角做了深入分析。同时,从细观上看,以颗粒接触数和纯转动率变量为中心,观察了试样内部颗粒的运动状态,对比了不同剪切方向下剪切带内外颗粒接触数与纯转动位移的变化。最后,将数值试验结果与已有的室内试验结果进行了对比。此研究实现了复杂应力条件下空心扭剪试样的三维离散元模拟,加深了对空心扭剪试验过程和结果的理解和解释。
In order to analyze the shear mechanical properties of sandy soil under complex stress conditions, the commercial discrete element software PFC3D was used to simulate the hollow torsional shear test of the compact sand in the single-grain group, and the stress-strain relationship of the numerical sample was analyzed. The effects of the strength, volumetric strain, and intermediate principal stress ratios of discrete media under different shear directions were reproduced, and the evolution of the force chain during loading was reproduced, and the inclination of the shear zone was further analyzed. At the same time, from the microscopic point of view, with the particle contact number and the pure rotation rate variable as the center, the movement state of the particles inside the sample was observed, and the change of the contact number and the pure rotation displacement between the inside and outside particles of the shear band in different shear directions was compared. . Finally, the numerical test results are compared with the existing indoor test results. This study achieved three-dimensional discrete element simulation of hollow torsional shear specimens under complex stress conditions, which deepened the understanding and interpretation of the hollow torsional shear test process and results.