Firstly the initial crack length is calculated according to the stress wave theory: then, the ultimate cracking length caused by blasting is got by the brittle fracture theory of rock.

• 然后按照岩石的脆断理论计算爆生裂缝的最终扩展长度，对预裂爆破中爆炸作用过程和裂缝的扩展机理进行分析。