三维非连续变形分析方法碰撞分析及其应用

将具有完备动力学理论的非连续变形分析(DDA)方法应用于块体碰撞研究。基于三维DDA(3D DDA)方法,按时步输出块体碰撞过程速度变化和接触嵌入量,进而得到块体碰撞恢复系数、冲量、冲击力。以此为参考指标,采用斜抛、面-面对心等碰撞模型,验证3D DDA方法模拟块体碰撞的有效性,并将3D DDA方法应用于多米诺骨牌倾倒、滚石边坡成灾及防护等算例分析,探讨了多米诺骨牌倾倒机制、滚石启动及运动行为、滚石灾害防护方案。结果表明:多米诺骨牌间距越大,同一块体被碰撞时间越迟,其最终稳定时间也越迟,与下一块体碰撞的动能越大;滚石运动呈侧向平动及转动三维运动特征,每一次碰撞,均引起动能、轨迹或状态的显著变化;滚石拦挡设施弹簧刚度越大,越先达到最大冲击力,最大冲击力随弹簧刚度的增加而减小;可结合树木阻挡效应,耗散滚石动能,降低滚石飞跃高度,使滚石灾害减轻或控制在防护范围以内。

A three-dimensional discontinuous deformation analysis method for collision analysis and its application

A discontinuous deformation analysis(DDA)method with complete dynamic theory is applied to the collision research of blocks.Based on the three-dimensional DDA(3D DDA)method,the change of velocity and the depth of contact penetration in the process of block collision are output step by step,and then the coefficient of restitution,impulse and impact force of block collision are obtained.Taking these outputs as reference indexes,the validity of the 3D DDA method in simulating block collision is verified by using the oblique projectile and face-to-face collision models.The 3D DDA method is applied to the case analysis of domino toppling,rockfall slope disaster and its protection,and the toppling mechanism of dominoes,the initiation and motion behaviors of rockfall and the protection scheme of rockfall disaster are discussed.The results show that the larger the distance between dominoes,the later the collided time of the same block,the later the final stabilization time,and the greater the kinetic energy of the collision with the next block.Rockfall shows three-dimensional motion characteristics of lateral translation and rotation,and each collision causes significant changes in kinetic energy,trajectory or state.The greater the spring stiffness of the protective facilities,the earlier the maximum impact force is reached,and the maximum impact force decreases with the increase of spring stiffness.Combining with the barrier effect of trees,it can dissipate the kinetic energy of blocks,reduce the jump height of blocks,and make the rockfall disaster mitigation or being controlled within the protective scope.