跨孔法测试阻尼比的几个问题

Questions of damping ratio derived from cross-hole wave velocity test

阻尼比是抗震设计中要用到的一个岩土参数,阻尼比的测试方法大致有激振法测试(包括强迫振动和自由振动两种)、振动三轴和共振柱测试等几种。本文简述了阻尼比及衰减系数的物理概念,针对《岩土工程试验监测手册》中提出的跨孔法测试阻尼比的公式进行了推导,指出了手册中公式存在的错误,对跨孔法测试阻尼比的方法优缺点进行了分析;指明了跨孔法测试存在的问题,其实用性需要进一步考证。

As a geotechnical parameter, damping ratio is inevitably used in seismic design. There are several main methods for testing damping ratio, such as shock excitation test method （including forced vibration and free vibration）, dynamic triaxial and resonant column test methods etc. This paper presented the introduction of the physical conception of damping ratio and attenuation coefficient. Therefore, the author utilized the analytic derivation to analysis the formula of the cross-hole wave velocity test used for testing damping ratio in geotechnieal testing and monitoring manual. Finally, the author pointed out the existing mistakes of the formula, simply described the physical concept of attenuation coefficient and analyzed the advantages and disadvantages of the method of cross-hole wave velocity test of damping ratio. .As for the problems existing, in the method of cross-hole wave velocity test, their practicability is still needed to be further studied and confirmed.