Research On The Movement Law And Numerical Simulation Of The Fractured Rockfall During Impacting Fragmentation

Collapse is a highly variable geological phenomenon in which dangerous rock masses detach from the slope parent body under the action of gravity.At the same time,collapse is also a global geological disaster,with potential conditions for collapse development in mountainous and hilly areas worldwide.Rockfall is a natural phenomenon that is the main manifestation of collapse disasters.Due to the uncertainty and suddenness of falling rocks,they pose a great threat to human life and property.The frequent and destructive nature of collapse disasters makes it extremely necessary to study collapse disasters.At the same time,long-term research has found that in collapse disasters,the impact of falling rocks on people is more obvious,while in the collision of falling rocks,the "splashing" falling rock fragments have greater"killing power".In existing research,few scholars have studied the joint fragments generated after the collision and fragmentation of joint rocks.In this paper,a self-made crash test system is used to study the fragmentation caused by rockfall collision in joint fissure,and the influence of rock fall shape,number of joint blocks,falling height,collision Angle and joint strength on the characteristics of rockfall collision fragmentation is explored.The change law of energy loss and recovery coefficient after collision is analyzed.The main programmes and conclusions are as follows:(1)On the basis of literature review,the advantages and shortcomings of precast jointed rock bonding materials are analyzed and compared,and the feasibility of preparing jointed granite with granite debris as aggregate and gypsum and cement as auxiliary materials is determined,and the bonding strength can be controlled by adjusting the mix ratio of water and cement.(2)Based on the orthogonal test method,a series of indoor collision experiments were carried out by using the self-developed rockfall collision system,and the influences of factors such as rockfall shape,number of joint blocks,falling height,collision Angle and joint bond strength on the motion characteristics of rockfall(velocity,acceleration,energy loss and energy recovery coefficient)were analyzed in detail.The test results show that the impact Angle is the main factor that affects the analysis indexes of falling rock.With the increase of collision Angle,the velocity change of falling rock after collision fragmentation decreases,the maximum acceleration decreases,the energy loss decreases,and the energy recovery coefficient increases.The energy loss of falling rocks in cuboid is more than that in sphere and cube.With the increase of the number of fragments after falling rock collision,the energy lost by falling rock increases.The higher the height,the more energy is lost.The stronger the joint is,the more energy is lost.(3)ANSYS/LS-DYNA dynamic finite element software is used to conduct numerical simulation analysis on the process of rockfall impact slope.The results show that:using LS-DYNA finite element software and H-J-C model can better reflect the characteristics of rockfall impact fragmentation.In the process of numerical simulation,the changes of rockfall collision fragmentation morphology,displacement,velocity and acceleration are similar to the actual experimental results,indicating that the H-J-C model can be applied to simulate such conditions.Figure[28]table[17]reference[81]...