考虑粒间法向接触力作用的粗粒土颗粒破碎试验研究

利用岩石双轴流变试验机,采用砂岩、石灰岩和板岩3种材料模拟粗粒土进行了球-球法向接触的颗粒破碎力学试验,对粗粒土颗粒破碎的过程、破碎形态、弹性核和力-位移曲线进行了研究,分析了不同粗粒土材料和颗粒尺寸对法向接触力学特性及颗粒破碎规律的影响。通过试验研究,发现粗粒土颗粒在法向接触力作用下,先在颗粒接触点处开始产生局部破碎,形成弹性核,继而产生贯通裂缝,最后颗粒发生整体破碎。通过拟合,分别建立了球形颗粒破碎准则和弹性核尺寸的经验公式。本文从粗粒土颗粒接触角度研究颗粒破碎的力学机理,开辟了研究粗粒土颗粒破碎的新途径,也可为离散元数值模拟直接提供接触力学参数。

Experimental study on particle breakage of coarse-grained soil considering normal contact force

The sandstone, limestone, slate are used to simulate the ball-ball normal contact of coarse-grained soil by employing the rock rheological testing system. The breakage process and morphology of particles, elastic core and force-displacement curve are used to analyze the influences of compressive mechanism and breakage characteristics of particles by considering the properties and particle sizes of materials. Through the experimental study, it is found that under the normal contact force, the local breakage occurs firstly at the contact area of the particle, thereafter the elastic core is formed, and the entire breakage of the particle occurs finally after crack coalescence. By data fitting, the breakage criterion for spherical particles and empirical formulae for elastic core sizes are established respectively. The mechanism of particle breakage is revealed from the perspective of particle contact of coarse-grained soil, and it opens up a new way to study the particle breakage of coarse-grained soil. It can also provide contact mechanic parameters directly for discrete element numerical simulation.