振动场中散体介质波的传播规律

Characters of Wave Propagation in Granular Media

非理想散体介质显现出非匀质性、各向异性和层状分布等特点 ,且有气、液、固三相 ,其波的传播比较复杂。当应变值ε <1× 10 - 4 时 ,散体介质为弹性介质 ,据此分析并给出了各向同性散体介质中弹性波的波动方程、传播速度和波动能量的表达式 ,以及横观各向同性介质中弹性波的波动方程和能量透过系数表达式 ,并通过试验验证了能量衰减与分层介质密度有关。此外 ,根据瑞利波由P波和S波振动叠加而成的特点 ,分析了无限半空间各向同性介质和横观各向同性介质中瑞利波的传播特性 ;又由于勒夫波由SH波经多次全反射加强干涉产生 。

Real granular media manifest such characters as nonuniformity, anisotropy and lamellar distribution and have gas, liquid and solid phases. Therefore propogation of waves in them is very complex. When their strain number, ε less than or equal 1 × 10-4, they are elastic media. According to this, the authors analyse and give the wave motion equation of elastic waves in isotropic media and the expression of wave propogation velocity and wave energy, as well as the wave motion equation of elastic waves in horizontally isotropic media and the expression of energy penetration coefficient of elastic waves. The tests show that energy attenuation has relation to the density of layered media. Rayleigh wave is a type of superimposition wave forming by vibration of P and S waves. According to the characteristic, the authors analyse the propagation characters of Rayleigh wave in isotropic media and horizontally isotropic media in semi-infinite body. In addition, Love wave is a kind of interference wave which i s caused by total reflection of SH waves. The study shows that its characters depend on the thickness of granular media and the velocity of shear waves, etc.