空气间隔装药孔壁初始冲击压力分析

为分析空气间隔装药时孔壁的初始冲击压力,引入Starfield迭加法,将柱状药包等效为有限个单元球形药包,考虑压力沿炮孔轴向的衰减及叠加作用,分析得到上部空气间隔装药及中部空气间隔装药条件下的孔壁初始冲击压力计算表达式。利用ANSYS/LS-DYNA软件建立数值模型,对监测点进行应力监测;同时,浇筑混凝土模型,并借助高速多路动态应力测试系统测量炮孔周围爆炸应力场,将2种方式的监测结果与理论分析结果相比较。结果显示:上部空气间隔装药,装药段处压力达到最大,随着与装药段距离的增大,压力明显呈先急剧减小、后趋于稳定的趋势;中部空气间隔装药,压力最小值出现在空气柱约1/2处,整体呈两端大、中间小的下凹型分布特征。在2种装药结构下,空气柱中指定点初始冲击压力的理论值与模拟值相对误差均较小。上述结果充分表明:空气间隔装药孔内压力沿炮孔轴向呈不均匀分布,2种装药结构压力分布特征与理论分析结果基本吻合,验证了理论分析的合理性。

Initial shock pressure analysis for hole wall with air-decked charge

In order to analyze the initial shock pressure of hole wall with air-decked charge,the column charge is equivalent to a certain number of the spherical charges with Starfield method.Considering the attenuation and superposition of the pressure in the axial direction,the theoretical solution of the initial pressure acting on the hole-wall can be obtained for the charge conditions of up-air-deck and middle-air-deck,respectively.The stress monitoring is carried out with the numerical modeling by the software of ANSYS/LS-DYNA.Meanwhile,the stress field of explosion around the blast hole is also measured for the concrete model via the high-speed dynamic stress testing system.The comparison is conducted between the results obtained from the numerical measurements and theoretical solutions.Results show that the maximum stress occurs in the charging section for the up-air-deck charge condition.With the increase of the distance away from the charging section,the stress presents a sharp decrease first and maintains a relatively constant value.For the middle-air-deck condition,the minimum stress occurs at the middle of the air column and the maximum stresses occurs at the both end of borehole.The relative errors between the initial impact pressures obtained from the theoretical solution and numerical model are relatively small for both the two charging structures.The above mentioned results indicate that the pressure distribution is nonuniform along the axial direction of the borehole.Meanwhile,the stress distribution characteristics for the two charge structures agree well with the theoretical results,which verifies the rationality of the theoretical solutions.