An Analysis Of Rock Failure And The Energy Consumption Under Different Dynamic Loading

The research of this dissertation, which is based on the threekinds of the rock,s SHPB impact test, strives to be the experimental study andtheoretical analysis closely together, and gets some achievements with reference to doeverything in one’s power, It provides help for the engineering practice and scientificresearch. Combined with the data collected from the test and the theoretical analysis,the main contents and conclusion are as follows:(1) The informative SHPB testing system and experiment principle wereintroduced, which derived the relevant relationship between the parameters andvariables.(2)In general, the stress and strain curve can be divided into four stages. Specificto the three kinds of rocks in the impact test, its performance is also different, whichmay be related to the properties of different rock itself. With the increase of impactvelocity, the peak stress was increased, and the peak time required has been reducedin the stress and time curve. The study, which used SHPB testing system, found thatthe average impact velocity and strain rate relationship are usually polynomial; Thedegree of correlation between the average strain rate and the elastic modulus is notvery good. A wide range of strain rate changes, while the impact velocity is large, inthe strain rate-time curve of the latter, there will have a rebound effect.(3)During the three kinds of the rock,s SHPB impact test, the damage forms offracturing present an axial cleaving mode as the major and crushing mode under thehigh impact velocity, tend to generate numerous debris and even powder. Collectingthree samples in5groups of different impact velocities can be seen obviouslydifferent fragments.(4) The results indicate that the energy consumption of fragmentation alsoincreased as the incident energy increasing; When the impact velocity is increased,three kinds of rock samples of the percentage of the large size block content isconstantly being reduced. The average size of the crushed rock and energy density arenot a simple linear relationship. In case of impact speed, the average size of thecrushed rock is reduced continuously, that have a certain correlation between these.With the increasing of crushing energy consumption, feature sizes have been reduced.The distribution of block size fragments is the good self-similarity, the fractaldimension D increases under the impact speed adding, It can be concluded that the fractal dimension D shows a significant linear correlation with the impactspeed;withever increasing the energy density of rock, the fractal dimension becomeslarger, which can be used to characterize the degree of rock crushing as an idealstatistical indicators.(5) the energy absorption of the rock is only associated with the wave impedanceof rock under the impact loading, It can be found that there is a peak point in thecurve of η and Csρs/C0ρ0,It tends a certain extent the negative correlation in the ratioof the reflected energy and the energy transmission and the energy of the incident.