【摘要】 提出了一种提高单孔法剪切波速测量精度的新方法——能量变化率的自回归曲线法。首先把剪切波的时程曲线变换为能量变化率时程曲线;然后对能量变化率时程曲线进行长短平均处理,拾取各测点P波和S波的大致初至;最后提出采用一种二次方自回归模型对初至附近的能量变化率曲线进行二次方自回归处理,精确拾取出各测点P波和S波的精确到时。采用此方法、互相关函数法和人工拾取法对某场地的剪切波速进行了对比分析。分析结果表明:此方法相比互相关函数法,具有更好的噪声抑制能力,不仅能精确地自动拾取出各测点的S波的到时差,也能更准确地自动拾取出各测点的P波的到时差。以人工拾取结果为参考,此方法在实际测试中具有很高的准确率和稳定性。此方法丰富了场地剪切波速分析方法。基于此方法、互相关函数法和人工拾取法,设计了一套剪切波波速的测试系统,此系统能自动分析出各测点的剪切波速和形成完整的报告。更多还原

【Abstract】 A new autoregression curve method based on energy gradient is proposed. It can improve the accuracy of measuring shear wave velocity with single-hole method. Firstly, the time-history curves of shear waves are transformed into a set of spatial energy gradient wave time-history curves. Secondly, short trigger average/long trigger average(STA/LTA) method is used to transform energy gradient wave time-history curves and pick the arrival times of P wave and S wave. Finally, a quadratic autoregression model is proposed to pick the accurate arrival times of P wave and S wave. The model is used to process the energy gradient curves near the arrival time. A comparing experiment is conducted to validate the theory. The shear wave velocities of one field tested with proposed method, cross-correlation function method and manual picking method are analyzed. The results indicate that in comparison with the cross-correlation function method, this method has a better inhibitory effect on noise, and not only can get accurately S shear wave velocity but also can get accurately P shear wave velocity. Meanwhile the proposed method has much higher accuracy and stability in practical test relative to the manual picking analysis. This method enriches the automatic-picking methods of shear wave velocity. On the basis of method proposed in this paper, cross-correlation function method and manual picking method, a shear wave measurement system is designed. It is easy to pick shear wave velocity automatically and produce a test report by this system.更多还原