摘要
对平面P波在饱和半空间中凹陷地形周围的散射规律进行了研究,分析了入射波频率、边界渗透条件、孔隙率、泊松比等对散射的影响.研究表明,饱和情况(透水或不透水)与干土情况凹陷地形附近地表位移的差别很大,饱和情况与干土情况的地表位移出现相位漂移,饱和情况地表位移波长相对较大.当孔隙率较低时,边界渗透条件对地表位移幅值的影响很小,而当孔隙率较大时,边界渗透条件的影响则不可忽视:在不透水情况下,水平和竖向地表位移幅值的峰值均相对较大.随着入射频率的升高,孔隙率的影响逐渐增大,而且不透水情况下孔隙率的影响相对较大.随着泊松比的增大,水平位移幅值逐渐减小,竖向位移幅值则逐渐增大.泊松比较小时,边界渗透条件对位移幅值的影响较大;泊松比较大时,边界渗透条件对位移幅值的影响则较小.随着入射频率的升高,泊松比的影响逐渐增大.当孔隙率较小时,孔隙水压幅值较小但空间变化比较剧烈;随着孔隙率的增大,孔隙水压逐渐增大但空间变化逐渐平缓.当孔隙率达到临界状态时,孔隙水压显著增大;这与SV波入射情况完全不同.当入射频率较高时,孔隙水压幅值较大,且孔隙水压的空间变化比较复杂.
The diffraction of incident-plane P waves by a shallow circular-arc canyon in a saturated poroelastic half-space was studied in this paper. The effects of the incident frequencies, boundary drainage, porosity, and Poisson＇s ratio on the diffraction of incident-plane P waves were discussed. It is shown that the surface displacement amplitudes near the canyon in dry poroelastic and saturated poroelastic half-spaces are very different and that large phase shifts can be observed, and the wave length in a saturated poroelastic half-space is longer than that of the drained. For small porosity, the drainage condition has little influence on the surface displacement amplitudes. For large porosity, however, the effect of the drainage condition becomes significant and cannot be ignored. Both the surface horizontal and vertical displacement amplitudes for the undrained case are relatively larger; as the incident frequency increases, the effect of porosity becomes significant, and the effect for the undrained case is more significant. As the Poisson＇s ratio increases, the surface horizontal displacemerit amplitudes decrease gradually, but the surface vertical displacement amplitudes increase gradually; for low Poisson＇s ratio, the drainage condition has significant influence on the surface displacement amplitudes, however, for high Poisson＇s ratio, the effect of drainage condition becomes insignificant; as the incident frequency increases, the effect of Poisson＇s ratio becomes important. When the porosity is small, the surface pore pressures near or around the canyon are small but their oscillations are violent, and as the porosity increases, the pore pressures increase significantly but their oscilla tions become smoother; as the incident frequency increases, the pore pressures become larger and their oscillations become more complicated.
出处
《天津大学学报》
EI
CAS
CSCD
北大核心
2010年第6期523-529,共7页
Journal of Tianjin University(Science and Technology)
基金
国家自然科学基金资助项目(50908156)
天津市应用基础研究重点资助项目(07JCZDJC10100)
关键词
饱和半空间
凹陷地形
平面P波
散射
边界渗透条件
孔隙率
泊松比
saturated poroelastic half-space
canyon
plane P wave
scattering
drainage condition
porosity
Poisson＇s ratio
