|
Abstract The frequency and intensity of rockburst are more and more serious with the increasing of exploit depth. But the mechanism of rockburst in deep mine is not clear. Based on the actual situation of deep exploit，the anomalously low friction rockburst is put forward，and the anomalously low friction effect is introduced. With the vertical impact load and crustal stress，theoretical block model of anomalously low friction rockburst is established，and the variation of normally dynamic load on interface of coal rock mass is deduced. The study indicates that the normally dynamic load on interface of deep rock mass periodically changes under the vertical impulse load，and the generating of rockburst has critical depth zone，when the depths are 400–600，800–1 000，1 200 m，the wave period of normally dynamic load on interface is smaller，the frequency of wave is much faster，which is corresponding with the result of spot observe and the existing conclusion，and verifies the rationality of model. The normally dynamic load on interface changes sharply with different exploit depths，and cubic polynomial is satisfied between the maximal variance ratio of normally dynamic load on interface and exploit depth at 800–1 200 m. With the increasing of the intensity of impulse load，the maximal change amplitude of normal load reduces firstly and increases subsequently，and reaches to constant value at last. When the intensity of impulse load is 1 MPa，the maximal change amplitude of normal load is least，the static friction on interface changes to dynamic friction，the coal mass will slide and the anomalously low friction effect will be generated，thus the rockburst would be induced easily.
|
|
Received: 27 November 2012
|
|
|
|
2014, Vol. 33 
