地震学报
地震學報
지진학보
ACTA SEISMOLOGICA SINICA
2015年
4期
629-639
,共11页
饱和土%非均匀性%P-SV 波%反射与透射%动力响应%动力刚度法
飽和土%非均勻性%P-SV 波%反射與透射%動力響應%動力剛度法
포화토%비균균성%P-SV 파%반사여투사%동력향응%동력강도법
saturated soil%non-homogeneous%P-SV wave%reflection and trans-mission%dynamic response%exact dynamic stiffness method
基于 Biot 多孔介质波动模型，研究了非均匀饱和土层对平面 P-SV 波入射时的动力响应。考虑饱和土地基的物理力学特性沿厚度方向连续变化，利用亥姆霍兹矢量分解原理和动力刚度法，分析了平面入射 P-SV 波在非均匀饱和土层中的反射和透射，并给出了基岩表面和自由表面处反射系数和透射系数的计算表达式。基于理论推导结果，数值分析了平面 SV波入射下非均匀饱和土自由场地的动力响应，其中假设饱和土地基的物理力学性质沿土层深度按幂律梯度变化。数值结果表明，平面 SV 波入射所引起的地面位移与基岩位移之比均随土层厚度和土体的非均匀程度、波的入射角和入射频率的增加而减小，且其竖向位移比的减小更为显著，厚土层对地震波的耗散作用尤为明显。
基于 Biot 多孔介質波動模型，研究瞭非均勻飽和土層對平麵 P-SV 波入射時的動力響應。攷慮飽和土地基的物理力學特性沿厚度方嚮連續變化，利用亥姆霍玆矢量分解原理和動力剛度法，分析瞭平麵入射 P-SV 波在非均勻飽和土層中的反射和透射，併給齣瞭基巖錶麵和自由錶麵處反射繫數和透射繫數的計算錶達式。基于理論推導結果，數值分析瞭平麵 SV波入射下非均勻飽和土自由場地的動力響應，其中假設飽和土地基的物理力學性質沿土層深度按冪律梯度變化。數值結果錶明，平麵 SV 波入射所引起的地麵位移與基巖位移之比均隨土層厚度和土體的非均勻程度、波的入射角和入射頻率的增加而減小，且其豎嚮位移比的減小更為顯著，厚土層對地震波的耗散作用尤為明顯。
기우 Biot 다공개질파동모형，연구료비균균포화토층대평면 P-SV 파입사시적동력향응。고필포화토지기적물리역학특성연후도방향련속변화，이용해모곽자시량분해원리화동력강도법，분석료평면입사 P-SV 파재비균균포화토층중적반사화투사，병급출료기암표면화자유표면처반사계수화투사계수적계산표체식。기우이론추도결과，수치분석료평면 SV파입사하비균균포화토자유장지적동력향응，기중가설포화토지기적물리역학성질연토층심도안멱률제도변화。수치결과표명，평면 SV 파입사소인기적지면위이여기암위이지비균수토층후도화토체적비균균정도、파적입사각화입사빈솔적증가이감소，차기수향위이비적감소경위현저，후토층대지진파적모산작용우위명현。
Based on Biot’s model for saturated porous media,the dynamic responses of non-homogeneous saturated soil was studied by using Helmholtz vector decomposition principle and exact dynamic stiffness method (EDSM) when P-SV wave was incident from bedrock.Reflection and transmission of incident plane P-SV wave in non-homogeneous saturated soil were analyzed considering the continuous variation of physical and mechanical properties about saturated foundation along the thickness direction.As a consequence,the general calculation formulas about the reflection coefficient and transmission coefficient of bedrock and free-field on the both surfaces were given.As numericalexamples,assuming that the material properties of the saturated foundationhad an exponential law distribution and gradient variation along the thicknesscoordinate,the dynamic response of non-homogeneous saturated soil and freefieldto incident plane SV was discussed.The numerical results indicate that theratio of ground displacement to bedrock displacement decreases with theincrease of the thickness and heterogeneity index of saturated soil,incidentangle and frequency of seismic wave.The vertical displacement ratio decreasesmore significantly than the horizontal one.The dissipation of seismic wavecaused by the thickness of soil layer is obvious,which all should be taken intoaccount in engineering practice especially on complex layered situations.
