基于瑞雷波法的成都盆地场地剪切波速结构确定
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摘要
在2008年的汶川地震中获得了大量的有价值数据和资料,使得成都盆地成为了研究的热点。为了能够获得成都盆地场地剪切波速结构,为成都盆地及汶川地震的进一步研究提供基本数据支持,本文利用多道面波分析方法在成都盆地(E:103°～105°,N:30°～32°)布置了40个面波测点进行场地剪切波速结构和覆盖层厚度的调查,测点间距约20 km。获得了成都盆地场地等效剪切波速(VS20)和场地覆盖层厚度分布。结果显示,成都盆地的等效剪切波速呈现出明显的条带状分布,与盆地的地质构造形态相似;盆地中央等效剪切波速主要介于235～330 m/s之间。而在西北侧盆地边缘,等效剪切波速增大;等效剪切波速主要介于330～440 m/s之间。覆盖层厚度也有同样的趋势;盆地中央较厚,覆盖层厚度在8～32 m;在西北侧盆地边缘较薄,覆盖层厚度在7～12 m之间。
A lot of valuable materials and data were achieved during the 5.12 Wenchuan earthquake,which made the region of Chengdu Basin become more and more interested by researchers.In order to provide the basic materials of equivalent shear wave velocity and overburden of this region for further researches,a multi-channel analysis of surface wave method is applied to the region(E:103°～105°,N:30°～32°) in this paper to get the equivalent shear wave velocity structure and overburden of the basin.40 survey points are evenly distributed in the region with the point space about 20 km.The equivalent shear wave velocity(VS20) and overburden of the basin are obtained.The results show that the distribution character of equivalent shear wave velocity and overburden are similar to the feature of tectonic structure of the basin.At the center of the basin,the equivalent shear wave velocity is mainly in 235 m/s to 330 m/s.While to the northwest side of the basin,the shear wave velocity increases to the range of 330 m/s to 440 m/s.The thickness of the overburden has the same character consistent with the equivalent shear wave velocity.The overburden is thicker at the center of the basin in the range of 8 m to 32 m.While to the northwest side of the basin,the thickness of the overburden decreases to the range of 7 m to 12 m.
A lot of valuable materials and data were achieved during the 5.12 Wenchuan earthquake,which made the region of Chengdu Basin become more and more interested by researchers.In order to provide the basic materials of equivalent shear wave velocity and overburden of this region for further researches,a multi-channel analysis of surface wave method is applied to the region(E:103°～105°,N:30°～32°) in this paper to get the equivalent shear wave velocity structure and overburden of the basin.40 survey points are evenly distributed in the region with the point space about 20 km.The equivalent shear wave velocity(VS20) and overburden of the basin are obtained.The results show that the distribution character of equivalent shear wave velocity and overburden are similar to the feature of tectonic structure of the basin.At the center of the basin,the equivalent shear wave velocity is mainly in 235 m/s to 330 m/s.While to the northwest side of the basin,the shear wave velocity increases to the range of 330 m/s to 440 m/s.The thickness of the overburden has the same character consistent with the equivalent shear wave velocity.The overburden is thicker at the center of the basin in the range of 8 m to 32 m.While to the northwest side of the basin,the thickness of the overburden decreases to the range of 7 m to 12 m.
引文
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[2]Park C B,Miller R D,Xia Jianghai.Multichannel analysis of surface waves[J].Geophysics,1999,64(3):800-808.
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[5]李海兵,王宗秀,付小方,等.2008年5月12日汶川地震(Ms 8.0)地表破裂带的分布特征[J].中国地质,2008,35(5):803-813.LI Haibing,WANG Zongxiu,FU Xiaofang,et al.The surface rupture zone distribution of the Wenchuan earthquake(Ms8.0)happened on May12th 2008[J].Geology in China,2008,35(5):803-813.(in Chinese)
[6]王凤林,李勇,李永昭,等.成都盆地新生代大邑砾岩的沉积特征[J].成都理工大学学报:自然科学版,2003,30(2):139-146.WANG Fenglin,LI Yong,LI Yongzhao,et al.Sedmentary characteristics of the cenozoic Dayi conglomerate in Chengdu Basin[J].Journal ofChengdu University of Technology(Science&Technology Edition),2003,30(2):139-146.(in Chinese)
[7]师黎静,陶夏新,Robert Kayen,等.场地瑞利波频散特性的测试方法研究[J].地震工程与工程振动,2005,25(6):24-29.SHI Lijing,TAO Xiaxin,Robert Kayen,et al.Study on evaluation methods for Rayleigh wave dispersion characteristic[J].Journal of EarthquakeEngineering and Engineering Vibration,2005,25(6):24-29.(in Chinese)
[8]陈国兴,陈继华.地震动输入界面的选取对深软场地地震效应的影响[J].世界地震工程,2005,21(2):36-42.CHEN Guoxing,CHEN Jihua.A study on the influence of seismic wave inputing interface on the earthquake response of deep soft sites[J].WorldEarthquake Engineering,2005,21(2):36-42.(in Chinese)
[9]王超凡,邹桂高,刘金光,等.多道瞬态瑞雷波勘探应用研究[J].地质科学,2002,37(1):110-117.WANG Chaofan,ZOU Guigao,LIU Jinguang,et al.Study on application of multicahannel transient R wave exploration[J].Chinese Journal of Ge-ology,2002,37(1):110-117.(in Chinese)
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