【摘要】 脆性介质的损伤与破坏是力学中极为复杂、极具挑战性的难题之一,而地震是一类典型脆性介质的突发破裂或失稳。在地震等灾变发生前都会出现一定的前兆现象,地震之后地壳介质又会缓慢愈合,地壳介质的损伤愈合过程对地震预测具有重要的研究意义。首先介绍V.Lyakhovsky等提出的损伤流变模型,且结合岩石破坏声发射实验数据分析该模型的特点;进一步基于损伤力学,从Helmholtz自由能出发,并考虑地质材料的可愈合效应,建立一维损伤-愈合模型,采用数值计算的方法得到地质材料的损伤-愈合模式。用常数加载率的线性载荷叠加一个正弦扰动来模拟固体潮引力,模拟计算该加载条件下材料的损伤-愈合过程;同时也考察了整个损伤愈合演化过程中加卸载响应比值的变化情况,发现在灾变发生之前加卸载响应比值会出现明显异常、回落的现象。再次验证了加卸载响应比作为一种重要的前兆现象,能够定量地刻画介质的损伤演化过程,这也为加卸载响应比方法提供了更为坚实的物理基础。更多还原

【Abstract】 The damage and failure of brittle media are challenging and complicated issues in mechanics field. Earthquake is a kind of typical failure or instability of brittle medium. Taking earthquakes for example,some precursory phenomena can be observed before the occurrence of catastrophic failure,and the healing phenomenon will take place gradually after earthquakes in a long time. So the study on the damage-healing process of the earth crust media is very significant to earthquake prediction. The model of damage rheology proposed by V. Lyakhovsky is introduced at first,and the shortcomings of the model are analyzed using the data obtained by acoustic emission experiment of rock failure. Secondly,based on damage mechanics,Helmholtz free energy, considering the healing phenomenon of the earth crust media,a new damage-healing model is set up in one dimension,and the damage-healing pattern is calculated with numerical method. The damage-healing process of the media is simulated under load which consists of two parts,the constant loading rate and a sinusoidal perturbation,to simulate solid tidal stress;and the evolution of load/unload response ratio(LURR) during the damage-healing process is also investigated at the same time. The result shows that the LURR value successively experiences,i.e. abnormity appearing,rising to the peak value then decreasing sharply before the occurrence of the catastrophic failure. This result validates that LURR can describe the damage degree of materialsquantitatively and is a good forecast of catastrophic failure,which also can provide solid basis for LURR method in physics.更多还原