单轴压缩下软硬互层岩石破裂过程的离散元数值分析

Distinct element numerical analysis of failure process of interlayered rock subjected to uniaxial compression

采用离散单元法研究了软硬互层岩石材料在不同层面倾角条件下的单轴压缩破坏过程,并结合复合岩体破坏的理论分析,求解了交界面上的界面黏结应力。考虑弱相岩石和弱界面的影响提出了软硬互层岩体的强度曲线。结果表明:随着层面倾角的增大,岩石的单轴抗压强度和弹性模量,以及总裂纹数量呈先减小后增大,层面倾角90?时的强度甚至超过了0?时的强度。裂纹数量以剪切裂纹为主,而拉伸裂纹较少。互层岩体由于层间力学属性不同,极有可能在交界面处引起应力集中,使得在交界面附近裂纹最先萌生,裂纹进一步向交界面两侧岩体中扩展,从而引起宏观裂纹的出现,最终引起岩体的破坏。裂纹的萌生位置和扩展模式直接决定了岩体的最终破裂形态。层面倾角?=45°~75°的试件主要发生沿材料交界面的滑动破坏。层面倾角?=0°和?=90°的试件主要发生拉伸破坏。层面倾角?=15°和?=30°的试件呈现弱相材料的拉伸破坏与沿层面滑动相结合的复合破坏。建立的界面黏结应力表明界面的应力状态由弱相材料控制。

The failure process of interlayered rock with different orientation angles was investigated through distinct element method,and in combination with the fracture theory of stratified rock masses,expressions for the bonding stresses at the interface were established.The strength curve for interlayered rock was put forward with consideration of weak rock layer and interface.The results have shown that with the increase of orientation angle,the uniaxial compressive strength and modulus of elasticity,and total number of cracks decrease initially and then increase.The corresponding compression strength when β=90° is even higher than that when β=0°.Shear cracks occupy the majority of cracks in number and tensile cracks occupy the minority.Due to the composite material properties of interlayered rock,stress concentration is most likely to occur in the interface where cracks may initiate and propagate.The propagation of cracks expands into the nearby area and then causes macro-cracks to form,and finally lead to the total failure of the entire specimen.The initiation locations of cracks and propagation models largely determine the final failure pattern and are often tightly related to the interfaces.Samples undergo sliding failure on the interface for that with β=45°~75°,tensile failure for that with β=0° and β=90°,and combined failure with sliding and tensile failure for that with β=15° and β=30°.The stress state on the interface is controlled by the relatively weak rock layer.