SV波入射情况下V型河谷地形对地震动的影响分析
|
摘要
基于局部人工边界的显式有限元方法,给出了二维V型河谷地形在SV波垂直入射下地面运动数值解,并分析其地震动分布规律以及两侧不同的边坡角度对于地震动分布规律的影响。数值结果表明:谷底的角点、两岸靠近河谷的点、两侧谷坡靠近谷底的点以及靠近两岸的点,对地表位移有放大作用,而对其邻近区域地表位移有抑制作用。这是由于角点处存在面的相交和转化,使角点处和角点附近波的散射更为复杂,故波形转换更加强烈,并且以其为中心有一定的影响区域,越靠近这些角点波形转换越为强烈。峰值结果、传递函数结果和观测点质点运动轨迹结果都显示了这一规律。整体而言,右岸和右坡坡顶附近波形转换要比左岸明显得多,且对应两侧河岸相同的X向位移峰值,左侧河岸的影响范围要比右侧的影响范围大,这可能是因为右坡坡度更大导致波形转换要更强所致。两侧河岸质点运动轨迹最终都呈现逆进运动轨迹,有些观测点的逆进椭圆轨迹较明显,这可能是由于在河岸处SV波转换成面波所致。
A numerical solution to the 2D model of V-shaped canyon under the normal incident SV waves is derived by using the explicit finite element combining local artificial method,and the distribution rule of site ground motions and the effect of different slope angles on influence range of bank PGD are discussed.Based on the numerical results,it is found that the surface ground motions at the intersecting positions of valley bottom and the slope,the slope and the bank are great while the adjacent regions of these points is constrained.This may be due to the scatter of the SV wave and the wave-type conversion is rather complicated at the intersecting positions.And the closer to the intersecting position,the stronger the scatter waves appear.The rules above are proved by the results of PGD,amplitude of transfer function and particle motions.The wave-type conversion of the right bank and the right slope top is greater than that of the left side,and the influence range of the left bank is larger than that of the right bank,because the right slope angle is larger than that of the right side.The particle motion coda on both sides of the bank is viewed as the backward motion,and the backward elliptical motion of some observation points are very obvious.These calculations predict that at the bank on both sides the normally incident SV wave may be converted into Rayleigh wave.
A numerical solution to the 2D model of V-shaped canyon under the normal incident SV waves is derived by using the explicit finite element combining local artificial method,and the distribution rule of site ground motions and the effect of different slope angles on influence range of bank PGD are discussed.Based on the numerical results,it is found that the surface ground motions at the intersecting positions of valley bottom and the slope,the slope and the bank are great while the adjacent regions of these points is constrained.This may be due to the scatter of the SV wave and the wave-type conversion is rather complicated at the intersecting positions.And the closer to the intersecting position,the stronger the scatter waves appear.The rules above are proved by the results of PGD,amplitude of transfer function and particle motions.The wave-type conversion of the right bank and the right slope top is greater than that of the left side,and the influence range of the left bank is larger than that of the right bank,because the right slope angle is larger than that of the right side.The particle motion coda on both sides of the bank is viewed as the backward motion,and the backward elliptical motion of some observation points are very obvious.These calculations predict that at the bank on both sides the normally incident SV wave may be converted into Rayleigh wave.
引文
[1]首增恷,刘曾武,朱镜清.地震波在工程中的应用[M].北京:地震出版社,1982.
[2]周正华,王玉石,王伟,等.汶川地震中山脊地形效应-自贡西山公园事例[C]∥纪念汶川地震一周年研讨会论文集.北京:地震出版社,2009:58-64.
[3]Zhao Chenggang,Dong Jun,Gao Fuping.An analytical solution of three?dimensional diffraction of plane P waves by a hemispherical alluvialvalley with saturated soil deposits[J].Acta Mechanica Solida Sinica,2006,19(2):141-151.
[4]Zhao Chenggang,Dong Jun,Gao Fuping.Seismic responses of a hemispherical alluvial valley to SVwaves:a three-dimensional analytical approx-imation[J].Acta Mechanica Sinica,2006,22(6):547-557.
[5]张郁山.圆弧状多层沉积谷地在平面P波入射下稳态响应的解析解[J].地球物理学报,2008,51(3):869-880.
[6]张郁山.圆弧状多层沉积谷地在平面SV波入射下的动力响应[J].地球物理学报,2009,52(6):1547-1555.
[7]梁建文,巴振宁.弹性层状半空间中凸起地形对入射平面SH波的放大作用[J].地震工程与工程振动,2008,28(1):1-10.
[8]梁建文,巴振宁.弹性层状半空间中沉积谷地对入射平面SH波的放大作用[J].地震工程与工程振动,2007,25(3):1-9.
[9]李小军,廖振鹏,关慧敏.黏弹性场地地形对地震动影响分析的显式有限元有限差分方法.地震学报,1995,17(3):362~369.
[10]廖振鹏.近场波动的有限元模拟[J].地震工程与工程振动,1984,4(2):1-14.
[11]廖振鹏.工程波动理论[M].北京:科学出版社,2002.
[12]李小军.非线性场地地震反应分析方法研究[D].哈尔滨:国家地震局工程力学研究所,1993.
[13]刘晶波.局部不规则地形对地震地面运动的影响[J].地震学报,1996,18(2):239-245.
[14]景立平,卓旭场,王祥建.复杂场地对地震波传播的影响[J].地震工程与工程振动,2005,25(6):16-23.
[15]Zhao Chongbin,Valliappan S.Incident P and SV wave scattering effects under different canyon topographic and geological conditions[J].SoilDynamics and Earthquake Engineering,1993,12(3):129-143.
[16]Zhang Chuhan,Zhao Chongbin.Effects of canyon topography and geological conditions on strong ground motion[J].Int Journal of EarthquakeEngineering and Structural Dynamics,1988,16(1):81-97.
[17]刘必灯,李小军,周正华,等.SV波入射下V型河谷地形及地质条件对地震动峰值的影响分析[J].土木建筑与环境工程,2010,32(S2):155-157.
[2]周正华,王玉石,王伟,等.汶川地震中山脊地形效应-自贡西山公园事例[C]∥纪念汶川地震一周年研讨会论文集.北京:地震出版社,2009:58-64.
[3]Zhao Chenggang,Dong Jun,Gao Fuping.An analytical solution of three?dimensional diffraction of plane P waves by a hemispherical alluvialvalley with saturated soil deposits[J].Acta Mechanica Solida Sinica,2006,19(2):141-151.
[4]Zhao Chenggang,Dong Jun,Gao Fuping.Seismic responses of a hemispherical alluvial valley to SVwaves:a three-dimensional analytical approx-imation[J].Acta Mechanica Sinica,2006,22(6):547-557.
[5]张郁山.圆弧状多层沉积谷地在平面P波入射下稳态响应的解析解[J].地球物理学报,2008,51(3):869-880.
[6]张郁山.圆弧状多层沉积谷地在平面SV波入射下的动力响应[J].地球物理学报,2009,52(6):1547-1555.
[7]梁建文,巴振宁.弹性层状半空间中凸起地形对入射平面SH波的放大作用[J].地震工程与工程振动,2008,28(1):1-10.
[8]梁建文,巴振宁.弹性层状半空间中沉积谷地对入射平面SH波的放大作用[J].地震工程与工程振动,2007,25(3):1-9.
[9]李小军,廖振鹏,关慧敏.黏弹性场地地形对地震动影响分析的显式有限元有限差分方法.地震学报,1995,17(3):362~369.
[10]廖振鹏.近场波动的有限元模拟[J].地震工程与工程振动,1984,4(2):1-14.
[11]廖振鹏.工程波动理论[M].北京:科学出版社,2002.
[12]李小军.非线性场地地震反应分析方法研究[D].哈尔滨:国家地震局工程力学研究所,1993.
[13]刘晶波.局部不规则地形对地震地面运动的影响[J].地震学报,1996,18(2):239-245.
[14]景立平,卓旭场,王祥建.复杂场地对地震波传播的影响[J].地震工程与工程振动,2005,25(6):16-23.
[15]Zhao Chongbin,Valliappan S.Incident P and SV wave scattering effects under different canyon topographic and geological conditions[J].SoilDynamics and Earthquake Engineering,1993,12(3):129-143.
[16]Zhang Chuhan,Zhao Chongbin.Effects of canyon topography and geological conditions on strong ground motion[J].Int Journal of EarthquakeEngineering and Structural Dynamics,1988,16(1):81-97.
[17]刘必灯,李小军,周正华,等.SV波入射下V型河谷地形及地质条件对地震动峰值的影响分析[J].土木建筑与环境工程,2010,32(S2):155-157.
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心