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本文收集了733个四川地区的实测钻孔数据,从中筛选出深度大于30m的268个钻孔剖面资料。分别获得了10m、15m、20m、25m和28m不同深度处的平均剪切波速_s(d)与_s(30)的对数线性相关关系。同时还与Boore(2004)的结果做了对比分析,比较了采用常数外推法和对数线性外推法得到的不同深度处剪切波速的残差分布。结果表明,不同深度处剪切波速_s(d)与_s(30)的对数相关关系可能具有一定的区域性特征,本文得到的对数关系更适合四川地区。对数线性外推法与常数外推法相比,前者的系统偏差更小;随着深度的增加,两种方法的外推误差均逐渐减小,但常数外推法普遍低估了_s(30)值;当深度较浅时,低估的情况更为明显。本文的研究结果为利用大量的不足30m的钻孔资料估计_s(30)值提供了参考。
This paper collected 733 measured borehole data in Sichuan Province, and selected 268 borehole profiles with a depth greater than 30m. The logarithmic linear correlation between average shear wave velocity _s (d) and _s (30) at different depths of 10m, 15m, 20m, 25m and 28m were obtained respectively. At the same time, the results of Boore (2004) are compared and analyzed. The residual wave distribution at different depths obtained by constant extrapolation and logarithm linear extrapolation is compared. The results show that the logarithmic correlation between the shear wave velocities _s (d) and _s (30) at different depths may have certain regional characteristics. The logarithmic relationship obtained in this paper is more suitable for the Sichuan region. The logarithm linear extrapolation method compared with the constant extrapolation method, the former system deviation is smaller; As the depth increases, the extrapolation errors of the two methods are gradually reduced, but the constant extrapolation method generally underestimates the _s (30 ) Value; when the depth is shallow, the undervaluation is more obvious. The results of this paper provide a reference for estimating the value of _s (30) using a large number of borehole data of less than 30m.