非均质岩石单轴压缩下损伤演化规律数值模拟研究

Numerical Simulation Study on Damage Evolution Law of Heterogeneous Rocks under Uniaxial Compression

岩石在单轴压缩直至破坏的过程较快,无法通过肉眼观察裂纹扩展形态,为定量分析花岗岩在单轴压缩下损伤演化规律,利用数值模拟软件模拟非均质花岗岩单轴加载过程,通过模拟模型在不同时步下破坏单元数量,基于有效承载面积的损伤变量理论,计算岩石的损伤变量,进而对非均质花岗岩损伤规律研究。研究结果表明:(1)花岗岩在数值模拟单轴压缩下,会产生共轭破坏(“X”型破裂),其裂纹最初产生的裂纹是由右上到左下的斜向裂纹,其次产生由左上到右下的斜向裂纹,最终形成“X”型共轭破裂;(2)在压缩与弹性阶段数值模拟损伤变量增加较少,在裂纹发展阶段数值模拟损伤变量开始以平均增幅为0.003 5缓慢增加,在峰后破坏阶段数值模拟损伤变量以平均增幅为0.035激增,与岩石时间与应力的曲线变化有很好的一致性。研究结果可对后续非均质岩石表面与内部裂纹发展相关性提供新的研究途径,进而为岩石破坏预警监测提供新的研究途径。

The process of rock failure under uniaxial compression is relatively fast,and the crack propagation morphology cannot be observed with the naked eye.In order to quantitatively analyze the damage evolution law of granite under uniaxial compression,numerical simulation software is used to simulate the uniaxial loading process of heterogeneous granite.By simulating the number of failure units at different time steps in the model,based on the damage variable theory of effective bearing area,the damage variable of the rock is calculated,Further research on the damage law of heterogeneous granite.The research results indicate that:(1)Granite undergoes conjugate failure("X"type fracture)under numerical simulation of uniaxial compression.The initial crack initiation is an oblique crack from top right to bottom left,followed by an oblique crack from top left to bottom right,ultimately forming an"X"type conjugate fracture;(2)In the compression and elastic stages,the numerical simulation damage variable increases relatively little.In the crack development stage,the numerical simulation damage variable gradually increases with an average increase of 0.0035.In the post peak failure stage,the numerical simulation damage variable increases sharply with an average increase of 0.035,which is consistent with the curve changes of rock time and stress.The research results can provide a new research approach for the correlation between the surface and internal crack development of heterogeneous rocks in the future,and thus provide a new research approach for rock failure warning and monitoring.