陡坎地形对地面运动的影响
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摘要
局部不规则地形对地震地面运动有很大影响。本文针对陡坎地形,采用数值模拟方法,探讨了不同坡角情形下,垂直入射不同SV波时陡坎地形对陡坎上侧(坡顶)和陡坎下侧(坡底)的影响程度和影响范围。结果表明:(1)陡坎上侧的放大系数大于水平自由地表,陡坎下侧的放大系数则小于水平自由地表;(2)x方向,随着坡角的增大,陡坎上侧的放大系数也增大,而陡坎下侧的放大系数随之减小;z方向,随着坡角的增大,陡坎上、下侧的放大系数都增大;(3)坡角发生变化时,陡坎下侧的影响范围基本不变,而在陡坎上侧,影响范围随坡角的增大有少许增加;(4)由于陡坎的存在,场地表面z方向出现了振动,放大系数随着坡角的增大而增大,放大系数与输入波有关,但是,x方向的放大系数受输入波的影响很小。
Local irregular topography has a great impact on earthquake ground motion.For scarp topography,using numerical simulation method,we discuss the influence extent and scope of the scarp terrain on scarp's upside and downside ground motion in case of different vertical incident SV waves.The results show that:(1) The amplification factor of scarp's upside region is greater than that of the free surface,while the amplification factor of scarp's downside part is less than that of the free surface;(2) When the slope angle increases,for x direction,amplification factors of the scarp upside also increase,while the downside part decrease with it;for z direction,both of the upside and downside amplification factors will increase;(3) When the slope angle changes,the influence scope of scarp's downside part is almost unchanged,but for the upside part,it slightly becomes greater with the increase of slope angle;(4) Due to the existence of the scarp,the z direction ground motion appears at the surface.Its amplification factor increases for larger slope angle,and the peaks of the surface responses are related with incident waves.However,the input wave has little effects on the x direction amplification factors.
引文
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