平面SV波斜入射下重力坝动力响应分析

Dynamic response analysis of gravity dam under oblique incidence of plane SV wave

为了研究地震动斜入射情况对重力坝的影响,在考虑无限地基辐射阻尼效应的前提下,基于隐式有限元结合应力型黏弹性人工边界的方法,通过大型有限元软件ANSYS APDL实现地震波等效荷载的转换,并从无限地基中截取三维地基验证了地震波等效输入的正确性,建立了重力坝-库水-地基-黏弹性人工边界的有限元动力分析模型,重点研究了平面SV波斜入射对重力坝坝体地震反应的影响。结果表明:随着平面SV波斜入射角度的增大,坝体关键部位的竖直向位移呈现出逐渐增加的趋势,顺河向位移呈现出逐渐降低的趋势,其中坝顶竖直向位移最大增加幅度达到52%,最大降低幅度达到34.9%;坝体关键部位的应力对平面SV波入射角度的改变敏感程度不太一致,其中坝踵处第一主应力呈现出逐渐降低的趋势,入射角度为30°时第一主应力最小值达到2.045 27 MPa,坝趾处的第三主应力呈现出逐渐增加的趋势,入射角度为30°时第三主应力最大值达到8.228 54 MPa,在同类工程设计中应重点关注。

In order to study the impact from oblique incidence of seismic wave on gravity dam,the equivalent load transform of seismic wave is realized through the large finite element software—ANSYS APDL based on the method of combining the implicit finite element with the stress-type visco-elastic artificial boundary under the premise of considering the radiation damping effects of unbounded foundation,and then the correctness of equivalent effect of seismic wave is verified by intercepting 3-D foundation from the unbounded foundation,thus a finite element dynamic analysis model of gravity dam-reservoir water-foundation-visco-elastic artificial boundary is established and the impact from oblique incidence of SV wave on seismic response of gravity dam is emphatically studied. The result shows that the vertical displacements of the key locations of dam body exhibit gradually increasing trends along with the increase of the angle of the oblique incidence of plane SV wave,while the displacements along river present gradually decreased trends; in which the maximum increasing amplitude of the vertical displacement of dam crest reaches to 52% with the maximum decreasing amplitude of 34. 9%. The sensitivities from the stresses of the key locations to the change of the angle of the oblique incidence of plane SV wave are not so coincided; in which the first-principal-stress at dam heel exhibits a trend of gradual decrease and its minimum value reaches to 2. 045 27 MPa when the incident angle is 30°,while the thirdprincipal stress therein presents a gradually increased trend and its maximum value reaches to 8. 228 54 MPa when the incident angle is 30°; on which great attention must be paid during the design of the similar project concerned.