山东地区等效剪切波速与30 m等效剪切波速转换研究

Study on the Conversion of Equivalent Shear Wave Velocity and 30 m Equivalent Shear Wave Velocity in Shandong Province

为实现等效剪切波速向30 m等效剪切波速的转换,根据覆盖层厚度的不同,分两种情况对山东地区等效剪切波速(V se)向30 m等效剪切波速(V S30)的转换进行了研究。当覆盖层厚度≥20 m时,通过最小二乘法拟合V se和V S30的对数线性关系,并与前人的研究结果进行对比。当覆盖层厚度<20 m时,采用基岩剪切波速拟合法:首先拟合基岩剪切波速与基岩深度的多项式关系式,然后推导V S30与等效剪切波速、覆盖层厚度、剪切波在基岩内的传播时间的关系式。对基岩剪切波速拟合法的V S30计算值进行验证,相对误差分布于区间[-2.89%,5.26%],相对误差绝对值小于3%的数据占比为87.5%。可见考虑覆盖层、基岩差异的基岩剪切波速拟合法是可行的。

In order to convert the equivalent shear wave velocity to 30 m equivalent shear wave velocity,according to the thickness of the overburden,the conversion of the equivalent shear wave velocity(V se)and 30 m equivalent shear wave velocity(V S30)in Shandong was studied in two cases.When the thickness of the overburden was 20 m or more,the logarithmic linear relationship of V se and V S30 was fitted by least squares method,and compared with the previous research results.When the thickness of the overburden was less than 20 m,the fitting method of shear wave velocity of bedrock was adopted.Firstly,the polynomial relation between the shear wave velocity of the bedrock and the bedrock depth was obtained.And then,the relationship between V S30 and equivalent shear wave velocity,overburden thickness and propagation time of shear wave in bedrock was derived.The calculated value of V S30 calculated by the fitting method of shear wave velocity of bedrock was verified.The results showed that the relative error is distributed in the range of[-2.89%,5.26%],and the relative error absolute value less than 3%accounts for 87.5%.It is concluded that fitting method of shear wave velocity of bedrock considering the difference between overburden and bedrock is feasible.