爆炸聚能作用下混凝土试件劈裂的高速3D DIC实验

为探寻非钻孔条件下露天爆破大块二次破碎形态的控制方法, 应用线性聚能射流对圆柱混凝土模型试件进行侵彻实验, 使用High-speed 3D DIC(高速三维数字图像相关方法)方法分析试件劈裂发展过程的全场三维形变特征。研究结果表明, 数据分析区内劈裂裂纹扩展速度在4个区间内呈阶梯式变化趋势, 峰值速度为235.52 m/s, 平均速度为140.89 m/s；线性聚能射流侵彻对劈裂裂纹扩展有明显导向作用, 应力集中作用使得劈裂裂纹围绕线性射流侵彻对称轴扩展, 扩展方向变化幅度较小；在劈裂裂纹扩展速度突变的3个时刻, 劈裂裂纹路径产生了3处明显拐点, 在拐点处伴随有支裂纹的产生, 支裂纹的扩展距离均未超过5 cm；主应变集中带形状及分布位置决定了裂纹扩展路径及趋势, 拉应变集中先于裂纹出现, 试件呈现准静态劈裂形态, 劈裂面平整度较高。

Study of the splitting crack propagation morphology using high-speed 3D DIC

To explore a method for control over the boulders splitting morphology, cylindrical concrete specimens were penetrated by a linear-shaped charge, the splitting cracks' propagation and development were photographed and the splitting development process of their 3D deformation characteristics were analyzed using high-speed 3D DIC. The results show that the velocity of the crack propagation within the data analysis region exhibits a tendency for a step-by-step increase. The peak velocity and the average velocity are respectively 235.52 m/s and 140.89 m/s. The impact of the linear shaped-charge jet plays a significant role in determining the splitting of the target so that the cracks of the target propagated symmetrically downward in an s-shape along the axis, and on its path the crack showed three obvious inflection points, where branch cracks were produced whose propagation distance was below 5 cm. The shape and location of the main strain concentration determines the crack propagation trend and path, and the tensile strain concentration occurs before the crack appears. The specimen exhibits a quasi-static splitting and the cracks have a fairly even distribution.