单孔不耦合装药爆破的岩体损伤分布特征研究

Distribution characteristics of the rock mass damage caused by single-hole decoupling charge blasting

开挖爆破作用下岩体损伤分布特征研究是地下工程围岩加固和边坡支挡防护设计的基础。通过弹性模量定义损伤因子以及对不耦合装药爆破进行损伤分区及其特征描述,应用Taylor提出的有效弹性模量计算方法,分别按照爆炸应力波衰减规律和厚壁圆筒理论建立相应的单孔爆破下损伤分布特征公式,进而叠加得到爆炸应力波与准静态气体共同作用下损伤分布特征公式。援引损伤实验数据分析其可行性和准确性,结果表明:该理论公式与实验数据的相关性较好,准确性较高,可表征爆破损伤分布特征及预估损伤范围;不耦合装药爆破的损伤因子呈幂函数衰减,其衰减速率在K≥K 0时呈逐渐减小的趋势,在K<K 0时呈先增大后减小的趋势,同时衰减速率又随着不耦合系数增大而增大;其他条件相同时,爆破损伤范围随着不耦合系数增大而减小;从损伤角度阐明了光面爆破或预裂爆破装药结构采用合适的不耦合系数的必要性。

The distribution characteristics of the rock mass damage under excavation blasting is a basis for the surrounding rock reinforcement in underground engineering and slope protection design.Defining the elastic modulus as a damage factor,the damage area caused by decoupling charge blasting was partitioned and its characteristics were described.With the application of the calculation method for the effective elastic modulus put forward by Taylor,the corresponding formulas of damage distribution characteristics under single-hole blasting were derived according to the attenuation law of explosive stress wave and the theory of thick-walled cylinder respectively,which were then superimposed to obtain a formula of damage distribution characteristics under the combined action of explosive stress wave and quasi-static gas.Damage tests data were cited to analyze the feasibility and accuracy of the method proposed.The results show that the theoretical formula,whose results correlates well with the test data and are of higher accuracy,can represent the distribution characteristics of blasting damage and estimate the damage scope.Damage factors of decoupling charge blasting are of exponential attenuation and its attenuation rate decreases gradually when K≥K 0 and first increases and then decreases when K<K 0,meanwhile,the attenuation rate increases with the increase of decoupling coefficient.Under the same other conditions,the damage scope decreases with the increase of decoupling coefficient.From the perspective of damage,it is necessary to apply appropriate decoupling coefficients to the smooth blasting or pre-splitting blasting charge structure.