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为了预测土壤颗粒在圆锥指数仪贯入沙土过程中的运动特性,该文通过建立一个三维长方体料床模型用离散元法模拟了圆锥贯入沙土的全过程,讨论了料床指定初始位置上颗粒的运动轨迹,还将料床的位移场按照位移量大小分成4个区,分析了料床的横向、纵向以及合成的位移场,最后给出了不同贯入深度的料床速度场及力链分布规律。研究结果显示:受到圆锥向下贯入和左右壁面阻挡的共同作用,大多数颗粒在圆锥贯入过程中以纵向移动为主,横向上体现为近似线性梯度的受限扩散式移动,尤以锥尖附近的横向位移最明显;颗粒在纵向上均经历了先向下运动再向上运动的过程,在圆锥贯入过程中料床的纵向位移场,作为向上和向下位移区的分界线,一条“衣领”带状区域的颗粒近似静止;越靠近锥尖附近的颗粒接触力和速度越大,且随着贯入深度的增加,锥尖处的接触力增大。该文的研究为土壤圆锥指数实地测量时测量点间距的取值提供理论依据。
In order to predict the movement of soil particles during conical index penetration into sandy soil, a three-dimensional rectangular bed model was established by discrete element method to simulate the whole process of cone penetration into sandy soil. The displacement field of the material bed is also divided into four zones according to the displacement. The lateral, longitudinal and synthetic displacement fields of the material bed are analyzed. Finally, the velocity field and the force chain with different penetration depths are given Distribution. The results show that most of the particles are mainly moved longitudinally during the process of conical penetration and confined and diffused almost linearly gradient laterally, especially under the action of cone penetration downwards and blockage of left and right walls. The lateral displacement near the tip is the most obvious. The particles undergo the first downward movement and then the upward movement in the longitudinal direction. The longitudinal displacement field of the material bed during penetration of the cone serves as the dividing line between upward and downward displacement zones. Particles in the “collar” band are approximately stationary; the greater the contact force and speed of the particles near the cone tip, and the greater the penetration force at the cone tip as the penetration depth increases. The research in this paper provides a theoretical basis for the value of the measured point spacing when the soil conical index is measured in the field.