| Mechanical rock fragmentation plays an increasingly important role in geotechnicalengineering fields for its advantages of continuity, safety, and efficient, etc. Therefore, it iswidely used in mining exploitation, tunnel construction, petroleum drilling and other fields.The previous theoretical and testing researches were mainly focused on the characteristics ofrock fracture and the forms of the most optimal loading under the effect of uni-static oruni-dynamic loads，but merely on the rock fragmentation under the effects of the combineddynamic and static loads. In addition, the chiseling depth, the rupture degree and the ratio ofthe rock crushing work were used in the experiments to judge the rock broken effect, but theabove methods were just concern with the results of the rock fragmentation, but little with themonitoring of rock broken process. For there is much less researches of using acousticemission technique to monitor the rock fragmentation under combined dynamic and staticloads, thus this thesis makes some theory analysis, numerical simulation, and laboratorytesting for the rock fragmentation under the coupling of dynamic and static loads from theangle of the acoustic emission.Based on summing and analyzing the characteristics of the rock fragmentation underuni-static and uni-dynamic loads, theory of physical mechanics and plastoelasticity wereapplied to analyze the force condition and broken characteristic in the process of cutterintrude into the rock，then obtained the equations of penetration force and wave undercoupling dynamic and static loads. Then on this basis, the formula of acoustic emission totalcount and energy by using the acoustic emission theory was obtained. The resultsdemonstrated that the AE count and energy under coupling dynamic and static are moregreater than uni-static and uni-dynamic load，and the time needed for reaching the maximumvalue is shorter. It showed that efficiency of broking the rock was improved by applyingcoupling loads.By using a realistic failure process analysis software(RFPA)，the AE numerical analysiswas carried out to analyze the granite and cement mortar block fragmentation under differentcoupling dynamic and static loads. The results showed that the AE energy undulates with thechange of cutter head force when using the static load to break rocks, the increase of the AEenergy was always corresponded with the decreased stages of force and reachs the maximumvalue at the time of the integrated rock cracking. When using the dynamic load to break rock，the lithology made a most profound effect on the rock broken and the AE energy. Theefficiency of broking rocks by applying coupling dynamic and static loads can be significantly increased，the total AE counts and energy is different from each other under different couplingloads. There existed a reasonable proportion of dynamic and static load which may make thetotal AE counts and energy both reach the maximum value.The multifunctional testing device for rock fragmentation under coupling dynamic andstatic loads was used to make a series of tests on the fragmentation of concrete，granite andcement mortar samples under different coupling loads. A high-speed motion picture camerawas also used to photograph the process of the rock fragmentation. The acoustic emission datawas collected and analyzed. The results showed that characteristics of the acoustic emissionduring rock breaking were different from different lithologic characters. The effect of the rockbreaking could be improved by using reasonable forms of loads. The coupling of dynamic andstatic loads created greater effects on the total acoustic emission count, energy and the depthof the rock fragmentation than uni-dynamic or uni-static loads. The theoretical analysis andnumerical simulation under the coupling dynamic and static loads that could improve the rockfragmentation effect were both verified by the laboratory test. |
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