脆性岩石破坏的能量跌落系数研究

Study of energy-drop coefficient of brittle rock failure

从能量角度出发,分析了脆性岩石的整个变形破坏过程。列举出岩石破坏过程的各种能量类型并对其分类,通过分析机械能和热能在岩石破坏过程中的不同影响,提出了用能量法分析岩石破坏过程必须区分热能与机械能。根据循环加、卸载曲线讨论了在岩石变形破坏的不同阶段输入的机械能?W与可释放应变能增量e?U以及耗散能增量d?U之间的关系及变化规律。分析了应力脆性跌落系数存在的不足,提出了一个新的表征岩石破坏的参量,即脆性岩石的能量跌落系数。对不同围压下大理岩和花岗岩破坏过程的应力-应变曲线分析计算,得到了能量跌落系数与围压的关系,以及损伤程度和泊松比对其影响。并通过与现有的应力脆性跌落系数进行对比,说明了本模型的合理性,并认为用其描述岩石的脆性程度在更广泛的围压条件下的适用性。

This paper analyzes the whole brittle failure process of rock from energy point, which enumerates and classifies variety of energy forms in the process of rock failure. It presents that thermal energy and mechanical energy must be distinguished when energy method is used to analyze the failure process of rock, because they have different effects. The relationship among input mechanical energy increment？W , releasable strain energy increment e？U and dissipated energy increment d？U is discussed through a symbolic cyclic loading-unloading curve;in addition, their transformation laws in different stages throughout the whole process are presented. The coefficient of brittle stress-drop has some shortcomings;and a new coefficient of energy-drop is presented in detail. Finally, this paper calculates energy-drop coefficient through the stress-strain curves in a series of confining pressure conditions of marble and granite, and obtains the relationship between the energy-drop coefficient and confining pressure. In addition, the effects of damage variable and Poisson＆#39;s ratio on energy-drop coefficient are discussed. The comparison between brittle stress-drop coefficient and energy-drop coefficient with the existing experimental data shows that our model is reasonable and can be applied to more wide confining pressure conditions.