不同胶结物粒间胶结三维仿微观力学试验

离散单元法被广泛应用于颗粒材料的力学特性研究,建立合理的胶结微观接触理论对实现胶结型岩土材料宏观、微观力学特性的数值分析显得尤为重要.首先通过室内三维接触试验方法制备由环氧树脂和高铝水泥胶结的铝球试样,并使用辅助加载装置进行拉伸、压缩、剪切、弯曲及扭转5种加载方式下的接触力学特性测试,为建立三维微观接触模型奠定试验基础.结果表明,胶结铝球颗粒的接触力学响应及强度包线与胶结物类型有关.在峰值前,胶结铝球的力-位移与力矩-转角变化关系曲线表现为线弹性;在峰值后,表现为环氧树脂偏塑性、高铝水泥偏脆性;法向作用力对胶结接触力学特性有重要影响,不同胶结铝球的抗剪、抗弯、抗扭能力随着法向作用力的增大呈现先增大后减小趋势,存在临界法向应力比;在不同荷载空间下,不同胶结铝球颗粒的归一化峰值强度包线(剪切强度、弯矩、扭矩-法向荷载)近似呈抛物线型.

Three dimensional Experimental Study on Mechanical Behavior of Cemented Granules by Different Bond Agents

The distinct element method had been widely used to study the macro & micro mechanical behaviors of granular materials, and hence it became more and more important to introduce a reasonable and accurate contact model, which can be applied in a 3D simulation of structured soils. The micro model test method was adopted to analyze the inter particle bond contact responses. Two types of bonded granules glued together with epoxy adhesive or aluminous cement were firstly prepared by a novel self designed apparatus, and then a series of tests, including tension, compression, shear, bending and torsion tests, were subsequently carried out using a rock rheological testing machine and some specific auxiliary loading devices. Test results show that the inter granular bond mechanics and strength envelopes are closely related to the cement agents. The force displacement and the moment/torque rotational angle relationships are approximately linearly in the pre failure stage, while they are different in the post failure stage for different cement agents, as plastic for epoxy and brittle for cement. Normal force performs a significant influence on the mechanical behaviors of inter hemisphere bond; both the critical normal force and stress ratio vary with the cement agent. Under different load space, the shapes of the strength envelopes, where the peak shear strength (shear strength, moment and torque versus normal force) appear near parabolic.