Observed and simulated fracture pattern in diametrically loaded discs of rock material
Observed and simulated fracture pattern in diametrically loaded discs of rock material
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DOI：
10.1007/s10704-004-3177-z
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发表时间：
2005-01-01
影响因子：
2.5
通讯作者：
Napier, JAL
中科院分区：
文献类型：
--
作者：
Van De Steen, B;Vervoort, A;Napier, JAL
为了研究拉伸应力梯度对岩石材料中裂纹萌生和裂纹扩展的影响，使用了一种结构，该结构由直径加载的圆盘组成，圆盘的直径上具有垂直于加载直径的孔。材料能够承受的最大局部拉伸应力随着应力梯度的增加而增加。取决于孔的直径和偏心率，盘沿着加载直径分裂或宏观破裂从孔开始。然而，在孔的顶部和底部的拉伸应力对于几乎所有的情况都显著高于沿着加载直径的应力和材料的宏观拉伸强度，这是通过传统的巴西试验确定的。为了更好地理解这种特殊的断裂行为，使用边界元代码DIGS进行实验的数值模拟，该代码允许将弱元素（缺陷），代表岩石材料中的缺陷和弱点。它示出的应力梯度上的应力集中的影响，在尖端的动员缺陷在于特定的断裂行为的起源在径向加载盘与孔。对新结构的研究也得出了一些关于径向加载圆盘失效的结论。基于缺陷模型，巴西试验中的断裂起始必须归因于位于靠近其中一个压板的区域中的活动缺陷的断裂生长。
To investigate the influence of a tensile stress gradient on fracture initiation and fracture growth in rock material, a configuration, consisting of a diametrically loaded disc with a hole on the diameter perpendicular to the loaded diameter, is used. The maximum local tensile stresses the material is able to withstand increase as the stress gradient increases. Depending on the diameter and the eccentricity of the hole, the disc splits along the loaded diameter or macro-fracturing starts at the hole. However, the tensile stresses at the top and the bottom of the hole are for nearly all cases considerably higher than the stress along the loaded diameter and than the macroscopic tensile strength of the material, determined by conventional Brazilian tests. To better understand this particular fracturing behaviour, numerical simulations of the experiments are conducted using the boundary element code DIGS, which allows the incorporation of weak elements (flaws), representing defects and weaknesses in the rock material. It is shown that the influence of the stress gradient on the stress concentration at the tip of mobilised defects lies at the origin of the particular fracturing behaviour in the diametrically loaded disc with a hole. The study of the new configuration leads also to a number of conclusions with regard to the failure in diametrically loaded discs in general. Based on the flaw model, fracture initiation in the Brazilian test has to be attributed to fracture growth of a mobilised defect, situated in the area close to one of the platens.