地震研究

利用有限差分方法,对宾川气枪试验中激发条件对气枪信号振幅的影响进行数值模拟。结果显示:水库水位对信号振幅的影响呈非线性关系,34 m为气枪激发试验的优势激发水位,能产生最强波形振幅能量,而水位变化的影响随距离缓慢减小。通过拟合给出了不同水位变化幅度与其产生的平均振幅变化率之间的幂函数关系,可为实际波形运用中去除水位变化的影响提供理论参考。波形振幅与激发能量及震源沉放深度呈近线性关系,即激发能量越大,震源沉放深度越深,气枪激发效果越好,越有利于进行远距离深穿透地下结构的探测。

Using the finite different method,we numerically simulate the effect of excitation factors on airgun signal in Binchuan Reservoir.The result shows that the relationship between the change of reservoir water level and airgun signal amplitude is nonlinear,there is an optimum water level range of 30～35 m for airgun firing test which can excitate the strongest energy of signal amplitude,in addition the influence of water level changing attenuates with distances.We also fit the power equation between the amplitude of water level changing and the average amplitude change rate it produced,so that we can use it to provide theoretical reference for removing the effect of water level changing in actual waveform application.The wave amplitude is linear with excitation energy and towing depth,that is the greater the energy and the deeper of the towing,the better the effect of excitation,the more conducive to detect remote and deep penetration underground structure.

引言
1 数值模拟激发条件的影响
2 分析讨论
3 结论

表1 数值模拟中模型介质参数<br/>Tab.1 Model media parameters used in numerical modeling

表1 数值模拟中模型介质参数
Tab.1 Model media parameters used in numerical modeling

图1 包含有限水体的层状介质模型<br/>Fig.1 Layer medium model containing limited water

图1 包含有限水体的层状介质模型
Fig.1 Layer medium model containing limited water

图2 振幅归一化的参考台波形<br/>Fig.2 Waveforms with normalized amplitude of ckt station

图2 振幅归一化的参考台波形
Fig.2 Waveforms with normalized amplitude of ckt station

图3 震中距为1 km处检波器记录的波形<br/>Fig.3 Waveform recorded by seismometer with epicenter distance of 1 km

图3 震中距为1 km处检波器记录的波形
Fig.3 Waveform recorded by seismometer with epicenter distance of 1 km

图4 所有检波器记录的波形沿距离的分布图<br/>Fig.4 Distribution of waveform traces for all seismometers with distance

图4 所有检波器记录的波形沿距离的分布图
Fig.4 Distribution of waveform traces for all seismometers with distance

图5 水体水位变化<br/>Fig.5 Change of water level

图5 水体水位变化
Fig.5 Change of water level

图6 4个台站接收的波形信号的最大振幅随水位的分布<br/>Fig.6 The maximum amplitude of waveform change with water level for 4 receivers

图6 4个台站接收的波形信号的最大振幅随水位的分布
Fig.6 The maximum amplitude of waveform change with water level for 4 receivers

图7 所有台站接收的波形信号的平均最大振幅随水位的分布<br/>Fig.7 The average maximum amplitude of waveform change with water level for all receivers

图7 所有台站接收的波形信号的平均最大振幅随水位的分布
Fig.7 The average maximum amplitude of waveform change with water level for all receivers

图8 水位增加1 m时振幅变化率随距离的分布<br/>Fig.8 Distribution of amplitude changing rate with distance with water level increasing of 1 m

图8 水位增加1 m时振幅变化率随距离的分布
Fig.8 Distribution of amplitude changing rate with distance with water level increasing of 1 m

图9 水位不同变化幅度引起的振幅变化率随距离的分布<br/>Fig.9 Amplitude changing rate induced by different water level changing amplitude with distance

图9 水位不同变化幅度引起的振幅变化率随距离的分布
Fig.9 Amplitude changing rate induced by different water level changing amplitude with distance

表2 水位变化幅度与对应的平均振幅变化率<br/>Tab.2 Water level changing amplitude with the average amplitude changing rate

表2 水位变化幅度与对应的平均振幅变化率
Tab.2 Water level changing amplitude with the average amplitude changing rate

图10 平均振幅变化率与水位变化幅度的拟合图<br/>Fig.10 Fit plot of the average amplitude changing rate and water level changing amplitude

图10 平均振幅变化率与水位变化幅度的拟合图
Fig.10 Fit plot of the average amplitude changing rate and water level changing amplitude

图11 所有台站接收的波形信号的平均最大振幅随激发能量的分布<br/>Fig.11 The average maximum amplitude of waveform change with excitation energy for all receivers

图11 所有台站接收的波形信号的平均最大振幅随激发能量的分布
Fig.11 The average maximum amplitude of waveform change with excitation energy for all receivers

图12 所有台站接收的波形信号的平均最大振幅随震源沉放深度的分布<br/>Fig.12 The average maximum amplitude of waveform change with towing depth for all receivers

图12 所有台站接收的波形信号的平均最大振幅随震源沉放深度的分布
Fig.12 The average maximum amplitude of waveform change with towing depth for all receivers

图13 震源沉放深度变化时振幅变化率随距离的分布<br/>Fig.13 Amplitude changing rate with distance for towing depth changing

图13 震源沉放深度变化时振幅变化率随距离的分布
Fig.13 Amplitude changing rate with distance for towing depth changing

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备注

引言

1 数值模拟激发条件的影响

2 分析讨论

3 结论

期刊信息