Genetic Algorithm Inversion of Rayleigh Wave Dispersion from CMPCC Gathers Over a Shallow Fault Model
Genetic Algorithm Inversion of Rayleigh Wave Dispersion from CMPCC Gathers Over a Shallow Fault Model
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DOI：
10.2113/jeeg10.3.275
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发表时间：
2005-09
影响因子：
1
通讯作者：
K. Nagai;A. O’Neill;Y. Sanada;Y. Ashida
中科院分区：
文献类型：
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作者：
K. Nagai;A. O’Neill;Y. Sanada;Y. Ashida
基于一维面波反演的横向剪切波速度成像在商业场地特征描述中正成为常规方法。应用遗传算法（GA）反演三层浅层垂直断层模型的基模瑞雷波频散。用二维有限差分法计算数据，然后将其整理成CMP互相关（CMPCC）道集，从该道集测量频散。扩散在模型的平坦部分上是相对平滑的，以及当扩散在尖锐的横向不连续上相等地居中时。当展布的五分之一到五分之二“悬于”断层之上时，波场散射会破坏低频色散。每个频散曲线反演使用一维正演模型，约束到四个层，参数允许在自由的限制范围内变化，除了层1剪切波速度。一个新的变化是，优化是部分导向，包括最成功的剪切波速度…
Lateral shear-wave velocity imaging, based on 1D surface wave inversion, is becoming routine in commercial site characterisation. A Genetic Algorithm (GA) is applied to the inversion of fundamental mode Rayleigh wave dispersion over a 3-layered, shallow, vertical-fault model. The data are calculated using a 2D finite difference method, then sorted into CMP cross-correlated (CMPCC) gathers, from which the dispersion is measured. Dispersion is relatively smooth over flat portions of the model, as well as when the spread is equally centered over the sharp lateral discontinuity. When between one and two-fifths of the spread is “overhanging” the fault, low-frequency dispersion is corrupted by wavefield scattering. Each dispersion curve is inverted using a 1D forward model, constrained to four layers, with parameters allowed to vary within liberal limits except the layer 1 shear-wave velocity. A novel variation is that the optimisation is partially directed, by including the most successful shear-wave velocity ...