强吸波矿物对微波辅助破岩效果影响规律及机制研究

Influence Law and Mechanism of Strong Wave-Absorbing Minerals on Microwave-Assisted Rock-Breaking Effect

为更深入分析微波照射岩石破坏机制及强吸波矿物含量对微波照射弱化岩石效果的影响程度,以玄武岩为研究对象,利用离散元软件PFC(particle flow code),建立多颗粒钛铁矿-辉石-斜长石三元介质玄武岩细观结构数值计算模型,对在高功率短时间的微波照射条件下强吸波矿物(钛铁矿)含量变化对微波照射后玄武岩裂纹的萌生、发展及强度弱化效果影响进行研究。研究表明:1)玄武岩试样经微波照射后,发现玄武岩内部首先在强吸波矿物与相对弱吸波矿物交界处产生大量沿晶裂纹,随后部分沿晶裂纹逐渐扩展并以最短连接路径穿过矿物形成穿晶裂纹;2)微波照射后,沿晶裂纹主要集中在钛铁矿-斜长石交界处,穿晶裂纹主要分布于钛铁矿和辉石;3)经微波照射,玄武岩试样产生不均匀性分布的损伤,增强了岩石韧性,随钛铁矿含量增加,经微波照射后玄武岩试样的峰值强度和弹性模量显著降低,应力-应变曲线起伏态势增强、峰值产生点提前,并且玄武岩试样的强度弱化程度与强吸波矿物钛铁矿含量之间呈现正比例关系。

To explore the rock damage mechanism under microwave irradiation and the influence of strong waveabsorbing mineral content on the effect of microwave irradiation on fracturing rocks,basalt is selected as the research object and the discrete-element program particle flow code is used to establish a microscopic-structure analysis model based on numerical calculation for ternary medium basalt composed of ilmenite,diopside,and plagioclase.The influence of the content variation of strong wave-absorbing mineral(ilmenite)on the initiation and development of basalt cracks and the strength weakening effect after microwave irradiation is examined under the irradiation conditions of high power and short time.The results show the following:(1)A large number of intergranular cracks occurred first at the junction between strong wave-absorbing minerals and relatively weak wave-absorbing minerals inside the basalt,and then,some intergranular cracks gradually expanded and passed through the minerals with the shortest connecting path to form transgranular cracks.(2)The intergranular cracks were mainly concentrated at the ilmenite-plagioclase junction,while the transgranular cracks were mainly distributed in ilmenite and diopside.(3)The basalt sample produced damage with uneven distribution,enhancing the rock toughness.Furthermore,with increasing ilmenite content,the peak strength and elastic modulus of the basalt sample significantly decreased,the stress-strain curve fluctuation increased,and the peak generation point advanced.Moreover,the degree of strength weakening of the basalt sample was directly proportional to the ilmenite content,which is a strong wave-absorbing mineral.