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为了研究岩石各向异性及非均质性对其破坏形式的影响,对含层理构造的非均质片麻岩进行了多组加载角度的巴西劈裂试验,获得不同层理方向片麻岩试件“抗拉强度”。其计算“抗拉强度”随着层理方向与加载方向夹角减小而迅速减小,当层理方向平行于加载方向时,计算“抗拉强度”可认为是片麻岩软弱层理面间的抗拉强度;当层理方向垂直于加载方向时,计算“抗拉强度”可认为是片麻岩岩石矿物基质的等效抗拉强度;当层理方向与加载方向夹角小于90°时,则属于拉–剪复合破坏形式,是片麻岩各向异性和非均质性共同作用的结果,此时对计算“抗拉强度”的应用需要特别谨慎。用UDEC程序建立离散单元数值模型,利用随机分布的条状块体集合,通过设置层理界面和矿物颗粒之间的接触参数,模拟层理构造对片麻岩破坏的影响。数值模拟与试验结果吻合较好,解释了劈裂破坏形式产生的机制,揭示岩石在荷载状态下的破裂过程是裂纹从萌生初期的无序分布,到受微观构造影响而有序集中的自组织过程。
In order to study the influence of rock anisotropy and heterogeneity on the failure modes, Brazilian cleavage tests with multi-group loading angles were conducted on heterogeneous gneiss with stratigraphic structure, Specimens “Tensile Strength”. The calculated “tensile strength” decreases rapidly with the decrease of the included angle between the bedding direction and the loading direction. When the bedding direction is parallel to the loading direction, the calculated “tensile strength” can be considered as gneiss Tensile strength between the soft layer and the surface of the soft layer; when the bedding direction is perpendicular to the loading direction, the calculated “tensile strength” can be regarded as the equivalent tensile strength of the gneiss rock mineral matrix; when the bedding direction and loading If the direction angle is less than 90 °, it belongs to the shear-shear composite failure mode, which is the result of the interaction of anisotropy and heterogeneity of gneiss. At this time, the application of calculation of “tensile strength” needs special caution . UDEC program is used to establish the discrete element numerical model. By using the randomly distributed bar-block sets, the influence of bedding structure on the gneiss damage is simulated by setting the contact parameters between the bedding and mineral particles. The numerical simulation is in good agreement with the experimental results, explaining the mechanism of the formation of splitting failure, revealing that the failure process of rock under load is the disorder distribution of cracks from the initial stage of initiation to the self-organized process.