粒状体流动法则的微观机制

Micro-mechanical study on the plastic flow rule for granular materials

粒状体力学方法为散粒体建立了一种理想化的数值计算模型,可以模拟粒状体的力学表现.本研究认为粒状体力学方法不是缩尺模型而是一种"几率场模拟",所依据的不是相似理论而是接触点附近的微观机制的一致性,所计算的每个结果只是该机率场的一个"样本",其可靠性服从统计规律.因此本研究用粒状单元法对于一组平面的圆盘的集合作了单向的探针试验,发现粒状体的塑性应变在某些条件下几乎符合非关联流动法则,另一些条件下不符合.即使符合该法则的场合,也稍有偏差,使得理论上认为非关连流动法则应该导致的Hill失稳现象实际上不会发生.以此证明了该方法的价值和适用性.

A set of numerical monotonic loading probe tests in terms of the granular element method is carried out in this paper. The mechanical behaviors exhibited in the, tests are often met with those in the case of sand or so. These results are suggestive to know the internal mechanism hidden behind the macroscopic behaviors. The results of probe tests before the transition point, where a big strain happens suddenly, support the elasto - plastic model, while the plastic incremental behavior almost obeys non-associated flow rule. A probability field simulation concept is put forward, which is expected to be the theoretical background of DEM and GEM.