基于颗粒流模型微波辅助破岩过程数值模拟

Numerical simulation of rock fragmentation under microwave irradiation using particle flow method

微波辅助破岩是一种新型的破岩技术,通过微波加热预先在岩石内部产生微裂纹,然后联合其它破岩手段,可以有效提高破岩效率。以吸波的方铅矿和透波的方解石组成的岩石颗粒为研究对象,采用颗粒流程序建立了细观数值模型,对微波照射下的岩石颗粒细观物理力学应进行了模拟分析,揭示了不同微波照射条件下岩石内部温度分布与演化以及微裂纹的产生与发展的规律。研究结果表明:微波照射下,方铅矿温度明显高于方解石,岩石温度呈不均匀分布,不同矿物之间存在温差;微波照射可以使岩石在时间很短及温度较低的情况下产生微裂纹;微裂纹主要由方铅矿的热膨胀引起,微裂纹以拉伸裂纹为主,极少部分为剪切裂纹。岩石内部微裂纹的分布形态主要取决于方铅矿在岩石中的分布;微波照射时,裂纹首先产生于方铅矿周围,继而向周边的方解石内扩展,相互连通后导致岩石破裂;在消耗能量相同的情况下,微波功率越高,需要微波照射时间越短,岩石内部温差越大,产生的裂纹数量越多,破岩的效率更高。

Microwave-assisted rock-breaking is a new rock-breaking technology,which can effectively improve the rock-breaking efficiency by using microwave heating to generate micro-cracks in the rock and combining with other rock-breaking methods.Taking the rock particles composed of wave-absorbing galena and transparent calcite as the research object,a mesoscopic numerical model is established using the particle flow program,and the physical and mechanical properties of the rock particles under microwave irradiation are simulated and analyzed.The distribution and evolution of internal temperature and the formation and development of microcracks in rocks under different microwave irradiation conditions are revealed.The results show that under microwave irradiation,the temperature of galena is obviously higher than that of calcite,the temperature distribution of rock is not uniform,and there is temperature difference between different minerals,and micro-cracks can be produced in the case of very short time and low temperature under microwave irradiation.The microcracks are mainly caused by the thermal expansion of galena.The main microcracks are tensile cracks with very few shear cracks.The distribution of microcracks in rock is mainly determined by the distribution of galena in the rock,and when exposed to microwave irradiation,the cracks first occur around galena and then propagate into the surrounding calcite,which results in the fracture of rock after being connected with each other.In the case of the same energy consumption,the higher the microwave power is,the shorter the microwave irradiation time is,the greater the temperature difference inside the rock is,the more cracks are generated,and the rock-breaking will be more efficient.