基于ANSYS/LS-DYNA的落石冲击力研究

落石冲击力的计算方法目前以半经验半理论算法为主，计算值与实测冲击力存在较大差别，其适用性、合理性一直未得到工程界一致认同。结合前人冲击试验结论，参考国内外具有代表性的5种冲击力计算方法，阐明了ANSYS/LS-DYNA软件分析落石碰撞地面问题的可行性，此法不仅能考虑落石形状、地面岩土体物理力学特性及其空间分布特征，而且还能考虑不同入射角的碰撞问题；同时还分析了落石入射角、落石形状对冲击力的影响规律。研究结果表明:①初始速度大小相同时，冲击力与入射角呈正线性相关，而冲击力与落石尺寸的关系曲线则为一条正相关的抛物线；②同样重量的落石，块状落石与球状落石形成的最大冲击力相当，而块状落石的平均冲击力则为球状落石的1.1～1.3倍；③球状落石与地面碰撞时最大冲击力约为平均冲击力的1.6～2.1倍，块状落石与地面碰撞时最大冲击力则约为平均冲击力的1.5～1.8倍。

Research on Rockfall Impact Force Based on ANSYS/LS-DYNA

At present the rockfall impact force is calculated mainly in semi-theoretical and semi-empirical methods, with a big difference between calculated value and measured value, and so its applicability and reasonableness has not been fully recognized by engineering experts. Based on previous test conclusions and five kinds of representative impact calculation methods used at home and overseas, feasibility is clarified for analysis of rockfall impact on the ground by ANSYS/LS-DYNA software. In this method, consideration is given to not only rockfall shape, physical and mechanical properties of ground rock and earth mass and their spatial distribution, but also collisions at different incidence angles. Finally the law of the impact of rockfall incident angle and rockfall shape on the impact force is analyzed. The result shows that, ① in case of same initial velocity, the impact force has a positive linear correlation with the incidence angle, while the relation curve of the impact force and the rockfall size is a positively related parabola; ②in case of the rockfall with same weight, the maximum impact force of spherical and square rockfall is comparable, while the average impact force of the square rockfall is about 1.1 to 1.3 times that of the spherical rockfall; and ③maximum impact force is about 1.6~2.1 times average impact force during collision of the spherical rockfall with the ground, while the maximum impact force is about 1.5 to 1.8 times average impact force during collision of square rockfall with the ground.