Experimental Study On The Process Of Rock Burst And Characteristics Of Rockburst In Deep Iron Ore

Rock burst is a common geological disaster in deep engineering,which often causes casualties and huge property losses.In order to simulate the rock burst induced by different mining depths,pressure rate of deep surrounding rock,excavation unloading and external dynamic disturbance,the large-scale true triaxial rock burst test instrument is used to reveal the formation process of rock burst from different tangential stresses and loading rate conditions,the rapid unloading energy accumulation rockburst under different axial principal stresses and dynamic disturbance factors.The results show that:1)The tangential stress gradient condition has obvious effect on the process of rock burst.The axial peak stress of the rock sample increases with the increase of the tangential stress gradient,which is similar to the "S-shaped curve";it shows the binary failure feature on the parent rock,when the "V-shaped" feature of the rock sample is obvious,the average block size of the debris decreases rapidly at first and then slowly after the failure;the increase of the shear stress intensifies the failure frequency of the rock sample,and the critical energy point of rock burst failure increases with it,which results in the increase of the rock sample rock failure frequency,and the energy released during rock burst failure is increased.2)It is found that the loading rate has an important effect on rock burst.The peak stress of rock sample increases approximately in quadratic function,and the expansion effect of rock sample in radial direction is more obvious than that in tangential direction.Under the gradient of loading rate,the depth of rock burst increases,and the increase of loading rate can obviously improve the failure degree of rock burst.Sharp inflection point of absolute energy accumulation curve,the energy released in the process of rock burst increases rapidly at the loading rate of 1?4 k N/s,and then keeps increasing slowly.3)For the rock burst of energy accumulation type under the rapid unloading,the rock sample shows the hysteresis of rock burst after the transient unloading.Under the high axial static stress,the greater the energy is accumulated by the rock sample under the high axial static stress,the shorter the time of rock burst process needs and the greater the degree of failure is.The energy released during the failure stage of rock burst shows a span order of magnitude growth when the axial static stress ratio is 100%,and the axial static stress affects the occurrence of rock sample.The axial static stress is the decisive factor that affects the degree of rock burst.4)The process of rock burst induced by dynamic disturbance is more complex.Only under high static stress can rock burst be triggered by disturbance.Under the same conditions,when seismic wave disturbance is applied,it is easier to trigger rock burst than sine wave disturbance.Under dynamic disturbance,tension splitting is more obvious;when the axial static stress ratio of sine wave disturbance increases by 3%,the energy released by rock sample in rock burst phase is multiplied.Under the disturbance of seismic wave,the increase amplitude of energy released during rock burst is small.Figure 57;Table 12;Reference 63...