Research On The Influence Of Shape,Mass And Feature Of Slope To Movement Characteristic Of Rockfall

With financial support of National Natural Science Foundation(ID:51108488),through large rockfall model test,the rock shapes?quality and characteristics of slope section were analyzed in order to find influence law of the sensitive parameters in the process of movement?At the same time,the value range of sensitive parameters was obtained?Based on the theory of kinematics,author deduced rockfall motion path and motion parameter calculation formula of two typical composite slope.The composite slope model test and numerical analysis show the correctness of the theory of rockfall movement,and revealed the motion law of sphere and cylinder rockfalls on the typical composite slope.The main results can be obtained as follows:?Slope surface and slope angle are the main influencing factors for the normal coefficient of restitution.Along with the slope surface pavement from hard to soft,the normal coefficient of restitution gradually decrease.As slope angle increased,the normal coefficient of restitution gradually increase.Along with the rock shape,height and quality increase or decrease,the normal coefficient of restitution do not have a regular variation.The most value of normal coefficient of restitution distributed below 0.4,and the percentage is 94%.The number of value below 0.3 will be 84.8%in the total number.The number of value below 0.1 will be 36.5%in the total number.It is obvious that the rock did not bounce at all during one third of the model test.Most of them just rolled from the slope after hitting on the surface.Based on the model test,the suggested normal coefficient of restitution value will be determined from slope surface and slope angle.When the actual value will be used,the surface is harder and the angle is larger,the value is higher;the surface is softer and the angle is littler,the value is lower.?Slope surface?slope angle?rock mass and falling height are the main influencing factors for the tangential coefficient of restitution.Along with the slope surface pavement from soft to hard,the tangential coefficient of restitution gradually increase.As slope angle increased,the tangential coefficient of restitution gradually decrease.As rock quality increased,the tangential coefficient of restitution gradually increase.As falling height increased,the tangential coefficient of restitution gradually decrease.Along with the rock shape change,the tangential coefficient of restitution do not have a regular variation.The most value of tangential coefficient of restitution distributed above 0.4,and the percentage is 98%.The number of value above 0.9 will be 25%in the total number.It is obvious that the rock did not lose much kinetic energy in tangential direction at all during one fourth of the model test.Based on the model test,the suggested tangential coefficient of restitution value will be determined from slope surface and slope angle.When the actual value will be used,the surface is harder and the angle is littler,the value is higher;the surface is softer and the angle is larger,the value is lower.?Slope surface and slope angle are the main influencing factors for the rolling friction coefficient.Along with the slope surface pavement from hard to soft,the rolling friction coefficient gradually increase.As slope angle increased,the rolling friction coefficient gradually increase.Along with the rock quality increase or decrease,the rolling friction coefficient do not have a regular variation.The most value of rolling friction coefficient distributed below 0.9,and the percentage is 97%.The number of value below 0.6 will be 82%in the total number.The number of value between 0.2 and 0.4 will be 43%.It is obvious that the value of spherical rock did not exceed 0.4 at all during half of the model test.Based on the model test,the suggested rolling friction coeficient value will be determined from slope surface and slope angle.When the actual value will be used,the surface is softer and the angle is larger,the value is higher;the surface is harder and the angle is littler,the value is lower.?Based on the model test,the main movement mode in the process of rock fall is rolling?collision and air movement,while the main movement mode on slope surface is rolling and collision,without sliding.When the rocks are smaller mass,the horizontal distance and ratio of offset more easily show great randomness.Along with rock mass increase,the horizontal distance and ratio of offset do not have a regular variation.Rock shapes have a great influence on the horizontal distance while no influence on the ratio of offset.The offset ratio and its change scope of cylindrical rock is larger and wider than spherical rock.The ratio of spherical rock is usually below 0.35,while the cylindrical is always below 0.65.Based on the model test,the suggested offset ratio value of two typical composite slopes will be available.Before using the actual value,the shape of the rock should be estimated.If the shape is similar to spherical rock,the value is lower,and if the shape is similar to cylindrical rock,the value is higher.