大豆粮堆力学特性的直剪试验研究

利用直剪仪针对 6种不同垂直压力(25、50、75、100、125和150kPa)下的大豆粮堆,在0.6、1.0和1.2 mm/min 3种不同剪切速率条件下,进行了系统的试验研究,探讨了剪切速率和剪应力-剪位移曲线规律,分析了大豆粮堆的强度特性和内摩擦特性。结果表明：大豆粮堆剪切变形可分为线弹性阶段、应力强化阶段、颗粒压缩阶段。通过直剪试验测得大豆粮堆抗剪强度符合摩尔-库伦强度准则,大豆粮堆在25至150kPa垂直压力作用下,粘聚力随剪切速率的增大而减小,内摩擦角随剪切速率的增大而增大。在同种垂直压力下,剪切速率越大,剪应力增长越快,但最终会趋于一致。随着垂直压力的增加,大豆粮堆软化程度下降。

Mechanical Behavior of Soybean Heap under Direct Shear Conditions

Direct shear tests were carried out on soybean heap under six different vertical pressures (25, 50, 75, 100, 125 and 150 kPa) with three different shear rates of 0.6, 1.0 and 1.2 mm/min. The shear rates and shear stress-shear displacement curves were discussed, and the strength and internal friction characteristics of soybean heap were analyzed. The results show that the shear deformation of soybean heap can be divided into elastic stage, vertical deformation stage and grain compression stage. The shear strength of soybean heap measured by direct shear tests conforms to the Mohr-Coulomb strength criterion. Under the action of 25-150 kPa vertical pressure, the cohesion decreases with increasing of shear rate while the internal friction angle shows an opposite changing trend. Under the same vertical pressure, the larger the shear rate is, the faster the shear stress increases, but the peaks eventually become the same. With the increasing of vertical pressure, the softening degree of soybean heap decreased.