爆破激振条件下的岩体阻尼测试方法研究

RESEARCH ON DAMPING TESTING METHODS OF ROCK MASS BASED ON BLASTING EXCITATION

岩体阻尼是岩体的重要动力学参数。块体激振试验法是目前现场岩体阻尼测试最主要的方法,但这种测试方法耗费较大。通过爆破激振来测求岩体的阻尼比是一种相对简便、高效的方法,该方法需要扣除因能量的几何扩散而产生的几何阻尼的影响。为此按黏弹性阻尼模型推导出通过面波衰减计算岩体阻尼比的公式,并在海阳核电厂分别采用单孔和多孔爆破激振进行岩体阻尼试验,对得到的试验数据采用小波包进行分析。为检验该测试方法的测试效果,在同一场地按照规范进行激振试验测试,测试结果表明:通过爆破激振法测得的岩体阻尼比略大于通过块体激振法测得的岩体阻尼比,爆破激振法测得的岩体阻尼比随着爆源距的增加而减小,爆破激振的振动频率对测得的岩体阻尼比有一定影响。测试的对比结果表明利用爆破激振产生的岩体振动信号中的信息来计算岩体阻尼比具有一定的可行性。

Rock mass damping ratio,as an important dynamic parameter of rock mass,is widely tested by block excitation testing method which costs much. Blasting excitation is a simpler and more efficient method than block excitation for rock mass damping ratio. It needs to consider influence of geometric damping induced by geometric diffusion of energy. Formula of calculating rock mass damping ratio in attenuation of surface wave is derived with viscoelastic model. In Haiyang Nuclear Power Plant,a test consisting single hole and porous blasting excitation was conducted and the test data were analyzed by wavelet packet. In order to verify result of blasting excitation test,block excitation method was tested under the same condition. Results show that the ratio from blasting excitation test is larger than that from block excitation test,and the ratio from blasting excitation test decreases with the increasing distance between explosion source and measuring point. Moreover,the rock mass damping ratio was affected by blasting vibration frequency. Comparison of experimental results showed that rock mass damping ratio could be obtained through blasting vibration information.