Differential Analysis Of Failure Characteristics Of Similar Jointed Rock Masses Under Static And Dynamic Load

There are many kinds of joints in nature,the internal structure of these joints is extremely complex,in which the cracks will become the internal defects of the rock masses,and these joints will be subject to a variety of dynamic and static load,and seriously affect its overall stability and some physical and mechanical properties.The failure characteristics and the damage and fracture mechanism of jointed rock masses are two strait issues to be solved in the study of rock engineering.Facing the need of the theoretical and practical research in rock engineering,it is necessary to make a prospective study.In order to study the mechanical properties and failure characteristics of different types of jointed rock masses under dynamic and static load,cement mortar was used as test similar material instead of natural rock masses according to similar model theory,through pouring different jointed types of model specimens to carry out uniaxial graded compression test and drop hammer impact test to research the mechanical properties and damage state comparison.The main conclusions are as followings.main conclusions are as follows.（1）Through the analysis of uniaxial compression test and drop hammer impact test,the failure modes of jointed specimens with different inclination angles are different under different loads,and the energy absorbed by the drop weight test specimen is more concentrated quickly.After the total incident energy reaching to the value of threshold,it cracks quickly until breaks down.But in static loading,the total incident energy will accumulate gradually with the increase of loading time,the specimen will be destroyed continuously during the whole loading process.（2）Through the analysis of the two experimental phenomena,it can show that different loading tests to the"Bu"type specimens with inclination joints lead to some differences in the crack morphology of the specimen.The crack is more complex under the falling hammer loading,while under the static loading,the dilatancy and expansion phenomenon can be occurred leading to the tensile cracks due to the"hoop effect"effect.（3）Through the observation and analysis of the failure modes of three joints specimens,it can be drawn that the development of cracks in the specimens under the impact loading is more irregular.And due to the transient impact of falling hammer,the impact force will not produce enough concentrated tensile stress at the joint tip,compared with the static loading failure,there are less secondary coplanar cracks under impact loading.（4）The failure characteristics of different jointed specimens under static and dynamic loads and mechanical property of that under static load were simulated respectively by PFC^2D software and compared with the indoor experimental results to verify the coincidence degree between the numerical simulation and the indoor test results.It can be used as a feasible way to analyze the destroyed characteristics of jointed rock masses under different loads.