花岗岩岩爆声发射时空熵值动态特征实验研究

Experimental investigation of dynamic characteristics of AE spatio-temporal entropy for granitic rockburst

对花岗岩开展室内真三轴条件下岩爆模拟实验,并运用声发射监测技术获得其变形破坏过程中声发射参数和空间定位信息。基于信息熵理论,分析试样在破坏过程中声发射事件在时空上从无序走向有序的演化过程,计算得到了声发射事件空间熵值和时间熵值。实验表明:岩石破坏前声发射能量突然大量释放,声发射事件出现空间积聚现象;空间熵值出现“震荡-上升-下降-小幅上升-急剧下降”和时间熵值出现“震荡-下降-小幅上升-急剧下降”的演化模式。2种熵值在岩爆发生前都出现了急剧下降的现象,可作为岩爆发生前兆信息,下降点可作为岩爆预警点。并运用耗散结构理论证明了岩石破裂失稳过程中时空熵值演化是一个远离平衡态的非线性动力过程。实验结果为岩爆预测提供了新的手段,对于实际矿山岩爆等动力灾害的预警具有一定的理论研究意义。

Under true triaxial stresses, rockburst simulation experiment of granite is carried out in laboratory. AE (acoustic emission) parameters and spatial location in the process of granite failure are obtained through AE technology. The evolution process of AE events from disorder to order is analyzed based on the information entropy theory, and the spatial and time entropy of AE events are calculated. The results have shown that the AE energy releases suddenly and the AE events accumulate in space before rock failure. The space entropy presents the evolution model of “shock-rise-drop-increase slightly-drop sharply” and the time entropy presents that of “shock-drop-increase slightly-drop sharply”. Both of the entropy shows a sharp decrease before rockburst, which can be viewed as precursor information of rockburst. The dropping point can be regarded as a predicting point. The dissipative structure theory is used to prove that the evolution of spati-temporal entropy is a nonlinear dynamic process away from equilibrium state. The results provide a new means for the prediction of rockburst, and have certain theoretical significance for predicting dynamic disasters such as rockburst in mines.