【摘要】 <正> 一、裂纹扩展的方向利用应变能密度理论,结合裂纹闭合的作用,研究混合型裂纹的扩展。在考虑裂纹闭合的影响时,我们仿照Mclintock和Walsh (1962)的思路,研究直的裂纹。薛昌明根据应变能密度理论研究混合型裂纹失稳扩展的问题。这个理论在裂纹扩展方向上给出比通常所用的最大拉应力理论更合理的结果,而且不必计算能量释放率就可以得更多还原

【Abstract】 Based on the strain energy density theory on the unstable growth of mixed mode cracks, this paper discusses some problemes on fracture law and activity characteristics of strong aftershocks oceured at the end of main fracture of large earthquakes. Combining some relative examples, it suggested: 1. the angle between fracture planes of this strong aftershock and its main earthquake should be much more than zero degree; 2. this strong aftershock should generally locate at the corner of attenuuation curve of aftershock frequence; 3. the relationship between fracture length and magnitude of strong earthquakes is quite close to the result obtained by Guo Zeng-jian and others. 4. the growth length is about 0.16 time that of main fracture.更多还原