两种岩石试件的“超声–回弹–密度”综合筛选法研究

Comprehensive screening method of “ultrasonic-rebound-density” for two kinds of rock specimens

为了尽量减少室内岩石力学试验结果的离散性,综合应用现有的无损检测技术,基于Hertz接触理论与能量守恒定律,从回弹法检测原理出发,研究"超声–回弹–密度"综合筛选法预测岩石强度的理论机制,建立岩石单轴抗压强度与密度、纵波波速、回弹值的多元回归模型;并结合地层CT扫描技术,提出现场岩体预测强度的方法。通过花岗岩、砂岩的无损检测试验,采用提出的模型获得2种岩石的预测抗压强度,与室内单轴压缩试验结果对比:预测强度的误差分别为-2.53%~2.06%,-3.09%~4.84%,2个拟合公式的相关系数均大于0.9。该方法的精确程度比以往的强度预测经验公式更高,可为不同工况下岩石分组提供参考依据,经过分组的岩样其强度预测误差可控制在±5%以内。

In order to avoid the discreteness in laboratory test of rock mechanics,with the current prevailing technology of non-destructive testing,in view of the Hertz contact theory and energy conservation law,and based on the principle of rebound detection,the mechanism of rock-strength prediction by ＂ultrasonic-rebound-density＂ comprehensive screening method is studied,and multiple regression models are established concerning the relationships of rock uniaxial compressive strength with density,rebound and compressional wave velocity. Thus combined with stratigraphic CT scanning technique,a new method to predict the compressive strength of rock mass is put forward. Then after the non-destructive testing of granite and sandstone,this paper obtained their predicted compressive strength with the models mentioned above. The predicted results deviate from the results obtained by lab test by no more than-2.53% to 2.06% and 3.09% to 4.84%,and the correlation coefficients of the two fitting formulas are both more than 0.9. Conclusions are that this method is much more accurate than previous empirical formulas and can provide reference for rock grouping under different working conditions,and the prediction error of the grouped rock samples ranges from-5% to ＋5%.