静态控制爆破破岩断裂贯通机制研究

摘要

Due to the insufficient of traditional rock breaking model in the extension length and time,the bore-hole was simplified as rock crack in plane by equivalent method,and the fracture mechanics model was proposed up-on breaking unit of rock-mass. On the basis of fracture mechanics stress intensity factor expression,crack tip was ob-tained by the static blasting pressure. Meanwhile,three stages of crack length formulas of borehole crack extension were deduced by the expression of critical extension velocity and stress intensity factor for rock,which was described in the static blasting of Charles Equation. These crack length expressions can effectively judge the extension course and time of borehole crack under the static blasting pressure,which provides theoretical foundation for the static blas-ting design. Taking rock bedding slope removing engineering in some expressway by the static blasting as an exam-ple,the law of borehole crack extension velocity tended to be identical with the critical extension of stress corrosion principle Charles,and the crack extension length of three stages were 6. 5 cm,26. 9 cm and 39. 8 cm respectively;under the condition of this blasting parameters,the borehole crack was damaged in the third stage,and its cut-through time was nearly 9. 5 h,which fit the on-site recording data well.%针对传统破岩断裂扩展模型在扩展长度和扩展时间上的不足,采用等效方法将钻孔在平面上简化为岩体裂纹,提出了基于岩体破裂单元的静态爆破断裂力学模型.通过静态爆破压的确定,采用断裂力学计算方法,获得了钻孔裂纹尖端的应力强度因子表达式.基于Charles方程描述的静态爆破岩石临界扩展速度与应力强度因子的关系式,得到了钻孔裂纹扩展的三阶段裂纹长度表达式,该裂纹长度可有效判定静态爆破压钻孔扩展历程和扩展时间,同时可为静态爆破设计提供理论依据.某高速公路顺层岩质边坡静态爆破清除工程应用表明,裂纹扩展速度的变化规律与Charles应力腐蚀压临界扩展原理较为吻合,三阶段裂纹扩展长度分别为6.5 cm、26.9 cm、39.8 cm,在此爆破参数条件下,裂纹在第Ⅲ阶段贯通破坏,经反算得出贯通时间约9.5 h,与现场观测记录的数据相吻合.