基于离散单元法的大豆力学特性研究

Study on Mechanical Properties of Soybean Based on Discrete Element Method

针对大豆颗粒粒径较大的特点,在室内大豆直剪试验的基础上标定大豆相应细观参数,采用离散单元法建立大型大豆直剪试验数值模型,验证了离散单元法模拟大豆直剪试验的可行性。分别设定试样的剪切速率、仓壁材料以及含水率为3个单一变量,其他参数为不变量,研究3个变量对大豆相关力学特性的影响,结果表明:试样的剪切速率在一定范围内变化时,大豆的抗剪强度峰值与内摩擦角变化不明显,但内部黏聚力由6.12 kPa增大至9.31 kPa;在仓壁材料由光滑面变为混凝土板的过程中,大豆的内摩擦角由26.9°增大至32.33°,抗剪强度峰值也出现了一定程度的增长,但其内部的黏聚力保持相对稳定;不同含水率的大豆的抗剪强度不同,在大豆含水率由12%增长至21%时,大豆的内摩擦角由26.9°增大至32.5°,内部黏聚力由6.12 kPa增大至11.01 kPa。

According to the characteristics of large particle size of soybean, the corresponding microscopic parameters of soybean were calibrated on the basis of soybean direct shear test. The numerical model of large soybean direct shear test was established by discrete element method. The shear rate, wall material and water content of the sample were set to three single variables, and the other parameters as invariants. The effects of three variables on mechanical parameters such as soybean shear strength were studied. The results showed that when the shear rate changes within a certain range, the shear strength peak and internal friction angle of soybean did not change significantly, but the internal cohesion increased from 6.12 kPa to 9.31 kPa;the material of the silo wall changed from smooth surface to concrete slab. During the process, the internal friction angle of soybean changed from 26.9° to 32.33°, and its shear peak strength also increased to some extent, but its internal cohesion remained relatively stable;the shear strength of soybean with different water content was different. When the water content of soybean increased from 12% to 21%, the internal friction angle of soybean increased from 26.9° to 32.50°, and the internal cohesive force increased from 6.12 kPa to 11.01 kPa.