超声波振动下非均匀岩石损伤过程数值模拟与试验

在振动载荷作用下,岩石内部细观缺陷的发展将导致其宏观力学性能的劣化。为了提高超声波振动碎岩效率,采用数值模拟与实验研究相结合的方法,对超声波振动下岩石内部的损伤过程进行分析;采用有限元与统计技术相结合的方法,建立岩石二维模型,引入损伤增量因子的概念,分析岩石非均匀性对岩石裂纹扩展过程的影响。研究结果表明:1)岩石材料在超声波振动下的损伤过程分为萌生、扩展、贯通3个阶段,随着非均匀系数的增加,岩石原始裂纹的扩展效率逐渐加快。2)损伤因子存在一个临界值,约为0.005 4:当某一时刻岩石的损伤因子低于0.005 4时,损伤增量因子与非均匀系数的响应关系不明显;当损伤因子高于0.005 4时,损伤增量因子随着非均匀系数的增大而急剧增大,此时岩石非均匀性对损伤因子的影响不容忽视。

Numerical Simulation and Experiment of the Damage Process of Heterogeneous Rock Under Ultrasonic Vibration

During dynamic loading process,the evolution of internal micro defects will lead to a remarkable degradation in macro mechanical properties of rock.To improve the efficiency of rock fragmentation,the internal damage process of rock under ultrasonic vibration was analyzed using numerical simulation method combined with experimental verification.A two-dimensional heterogeneous model of rock was established by means of finite element method and statistical techniques,and the concept of damage incremental factor was put forward.Based on established model,the influence of rock heterogeneity on crack propagation under ultrasonic vibration was analyzed.Results showed that the damage process of rock material under ultrasonic vibration could be divided into three stages,which were initiation,propagation and connection.With the increase in uniformity coefficient,the speed of original crack propagation in rock increased gradually.There was a critical value of damage factor which was 0.005 4 in this study.When the damage factor was less than the critical value,there was no obvious relationship between the damage incremental factor and homogeneity coefficients.Otherwise,the damage incremental factor increased sharply with the increased homogeneity coefficient of rock,when the effect of homogeneity coefficient on the damage factor could not be ignored.