加载速率对砂岩破碎及能耗特征的影响

为了研究应力波加载速率对岩石破碎与能量利用效率的影响,利用杆件纵向撞击面局部变形的非线性模型设计了5种不同曲率半径的锤头,获得了非等入射能与等入射能条件下不同加载速率的入射应力波,并对红砂岩进行了冲击试验.结果表明:随着应力波加载速率的增大,砂岩试样破碎块度的分形维数呈近似线性增长关系.在加载速率相同的情况下,砂岩试样破碎块度的分形维数随入射能的增大而增大.随着入射应力波加载速率的增加,破碎能耗密度增大.在加载速率相同的情况下,入射能越大岩石破碎能耗密度越大.在非等入射能条件下,岩石破碎过程中的能量利用率随着入射能的增大呈明显的下降趋势.实际生产中最优的应力波形必须综合考虑破岩效果和能量利用率等因素.

Effect of Loading Rate on Fragmentation and Energy Dissipation Characteristics of Sandstone

In order to study the effects of loading rate of stress wave on rock breaking and energy efficiency， 5 hammers with different radius of curvature were designed by using the nonlinear model of the local deformation in the longitudinal impact surface of the members. Incident stress waves with different loading rates were achieved under different and identical incident energy， and the impact test of red sandstones was conducted. The results showed that the fractal dimension of fragmentation of sandstone specimen increases linearly with the increase of the loading rate of stress wave. The fractal dimension of fragmentation of sandstone specimen increases with the increase of incident energy under the same loading rate. The energy dissipation density increases with the increase of loading rate of incident wave. Under the same loading rate， the greater the incident energy is， the greater the energy dissipation density is. The energy efficiency decreases obviously with the increase of the incident energy under different incident energy. In practice， the best incident wave must be designed considering the factors such as rock breaking and the energy efficiency.