微波照射下脆性岩石裂纹扩展临界条件及断裂过程研究  

Research on the criteria of crack propagation and the process of fracture in brittle rocks under microwave irradiation

作　　者：袁媛[1] 邵珠山[1] Yuan Yuan;Shao Zhushan(School of Civil Engineering,Xi’an University of Architecture and Technology,710055,Xi’an,China)

机构地区：[1]西安建筑科技大学土木工程学院,西安710055

出　　处：《应用力学学报》2020年第5期2112-2119,I0019,I0020,共10页Chinese Journal of Applied Mechanics

基　　金：国家自然科学基金(11872287);陕西省重点研发计划(2019ZDLGY01-10)。

摘　　要：基于热力学定律及Griffith断裂理论,建立了包含初始裂纹的脆性岩石理论模型研究微波破岩过程,推导了微波照射下均匀脆性岩石内部初始微裂纹的临界扩展条件。得到微波照射参数与裂纹扩展半径的关系呈V形曲线,且V形曲线上方为裂纹非稳定区域,下方为裂纹稳定区域。将V形曲线左半部分对应的裂纹定义为"初始短裂纹",断裂开始后,裂纹发生动态扩展,此时裂纹扩展行为不能由V形曲线完全描述,动态扩展的最终半径由能量守恒定律推导得到;当输入微波能量达到新的临界值之后,"初始短裂纹"则继续沿V形曲线发生准静态扩展。将V形曲线右半部分对应的裂纹半径定义为"初始长裂纹",对于初始长裂纹,输入的微波能量达到临界值之后,裂纹始终沿V形曲线以准静态方式扩展。根据裂纹扩展行为可以预测微波照射下岩石强度折减规律,其结果与已有实验结果吻合较好,对于指导微波辅助机械破岩工程实践具有重要意义。Following the thermodynamics and the general approach of Griffith, a theoretical model of brittle rock containing initial cracks is established to investigate the process of microwave breaking rocks, the criteria of initial microcracks propagation are derived for homogeneous brittle rocks irradiated by microwave. The relationship ofmicrowave irradiation parameters and extending radius of cracks can be shown as a V-shaped curve, and region of crack unstability locates above the curve, the region of crack stability locates below the curve. The cracks with radius corresponding to the left-hand side of the V-shaped curve are defined as "initial short cracks". After initiation of fracture, "initial short cracks" propagate kinetically, the propagation behavior cannot be described completely by the V-shaped curve, final radius after kinetic propagation can be derived by conservation law of energy;"initial short cracks" will extend quasi-statically along the V-shaped curve after a new critical microwave energy input is met. The cracks with radius corresponding to the right-hand side of the V-shaped curve are defined as "initial long cracks". For "initial long cracks", cracks propagate only in a quasi-static manner along the V-shaped curve after absorbing the critical microwave energy. The strength reduction behavior of brittle rocks irradiated by microwave is predicted according to the crack propagation behavior, good agreements with experimental results in references are found. The theory is of great significance for microwave-assisted comminution engineering.

关 键 词：微波 裂纹扩展 脆性岩石 断裂 强度折减 

分 类 号：TU45[建筑科学—岩土工程]