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高速地表环境下的主动源面波勘探研究

Study on active surface wave survey with a high-velocity top layer

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  • 维普
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高频(≥2 Hz)瑞雷面波的相速度频散特征已经被广泛用于确定浅地表横波速度,但仅反演几十Hz以内的相速度频散难以约束地表最浅部(譬如,＜0.2 m深度)的横波速度.此外,频散反演中不准确的表层横波速度亦会导致更深部横波速度反演结果的偏差.实际中,无论城市混凝土浇筑的马路或者铁路坚硬的道床都在地表呈现为显著高横波速度异常(＞1000 m/s)的薄层,此类地表环境下频散反演的结果可能会产生较大的偏差.相较于瑞雷面波频散,相同频率的瑞雷面波水平-垂直振幅比(H/V)对横波速度的敏感深度明显更浅.基于此,本文提出了一种基于主动源多道地震记录准确提取高频瑞雷面波H/V并联合反演瑞雷面波相速度频散和H/V的方法.本文通过高速地表理论模型的研究,表明引入H/V的联合反演显著改善了地表及更深部的横波速度的反演精度.该方法对高速地表条件下的城市道路检测及铁路路基病害识别具有重要工程意义.
The dispersive characteristics of high-frequency(≥ 2 Hz)Rayleigh-wave phase velocities have been widely used to determine the subsurface shear velocity.However,the shear velocity of the surface layers(e.g.,＜0.2 m depth)is poorly constrained in the dispersion inversion within tens of hertz.Furthermore,the inverted shear velocity at deeper depths can be biased due to inaccurate shear velocity at surface in dispersion inversion.In practice,both the concrete road under urban environment and rigid ballast bed of railway should be presented as a thin layer of distinct high(＞1000 m/s)shear velocity at the surface,the inverted results from dispersion inversion would be largely biased under these abnormal surface environments.Compared to the phase velocity,the Rayleigh-wave Horizontal-to-Vertical(H/V)ratios of particle motion are particularly sensitive to shallower shear velocity.Based on this idea,we propose a method for constructing Vs profiles based on the joint inversion of the Rayleigh-wave phase velocity dispersion and H/V from active-seismic records.According to the inversion results of synthetic data based on the model with high-velocity top layer,the accuracy of the shear velocity in the surface layer and underlying layers is considerably improved by joint inversion including H/V.The proposed method has great engineering significance for the detection of urban road and railroad bed diseases under high-velocity surface layer conditions.

High-velocity top layerRayleigh-wave phase velocity dispersionH/VJoint inversionShear velocity

胥鸿睿、刘泽鹏、程天健、尹晓菲、孙石达

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西南交通大学地球科学与工程学院,成都 611756

武汉理工光科股份有限公司,武汉 430079

中国地震局地震预测研究所,北京 100036

河北地质大学,自然资源部京津冀城市群地下空间智能探测与装备重点实验室,石家庄 050031

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高速地表 瑞雷面波相速度频散 H/V 联合反演 横波速度

国家自然科学基金国家自然科学基金四川省自然科学基金河北省自然科学基金中央高校基本科研项目中央高校基本科研项目

418041394190405923NSFSC3001D20224030442682023CX0152682023CX011

2024

10.6038/pg2024HH0385

地球物理学进展
中国科学院地质与地球物理研究所 中国地球物理学会

地球物理学进展

CSTPCD北大核心
影响因子：1.761
ISSN：1004-2903
年,卷(期)：2024.39(4)
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