工程场地浅层剪切波速结构反演

目的反演工程场地浅层剪切波速结构,验证中美联合地脉动台阵观测记录适合应用于实际工程场地的浅层剪切波速结构.方法对唐山地区两个实际场地观测,从地脉动台阵观测竖向记录中提取了Rayleigh波相速度频散曲线,从地脉动台阵3分量记录中提取了Love波相速度频散曲线,采用Haskell矩阵计算理论的Rayleigh波和Love波相速度.结合遗传算法与单纯形结合的反演算法对唐山地区的两个具体场地浅层剪切波速度结构进行了反演,并与实际的钻孔资料进行了对比.结果场地1提取的相速度频散曲线与理论计算结果有一定的差别.场地2提取的相速度频散曲线与理论计算结果符合较好,场地2的剪切波速结构反演结果较好,与钻孔资料的平均误差均在20%以内.结论利用从地脉动记录中提取Rayleigh波和Love波相速度频散曲线,反演场地剪切波速结构效果较好,适用于实际工程场地的浅层剪切波速度结构反演.

Research on Inversion Shallow S-wave Velocity Structure of Practical Sites

Shallow S-wave velocity structure is inversed with microtremors array records observed by China- US joint observation group, which shows that the microtremors array records can be applied to inverse shallow S-wave velocity structure of practical sites. The microtremors array observations are carded out in two practical engineering sites in Tangshan area. The phase velocities of Rayleigh wave are estimated from vertical component records and those of Love wave are estimated from three-component records of microtremors array. Haskell matrix method is used in calculating Rayleigh and Love wave phase velocities and the shallow S-wave velocity structure of two practical sites is estimated by means of a hybrid approach of Genetic Algorithm and Simplex. The inversed results are compared with the PS logging data of two sites. Extracted dispersion curve is different from the calculation result due to environmental factors in data collection in site 1, while, extracted dispersion curve and the calculation result are agreed well in site 2. The shear wave structure inversed in site 2 is better and the average errors are all less than 20% compared with the PS logging data. Phase velocities of Rayleigh wave and Love wave can be extracted from microtremors array records and S-wave structure of practical engineering site is inversed better. The method can be applied to inverse shallow S-wave velocity structure of practical engineering site.