基于钻孔脉动分析土层剪切波速

Analysis of soil shear wave velocity based on borehole microtremor

土层剪切波速是建筑场地类别划分、场地地震反应分析及地基饱和砂土液化判别的重要参数。工程上常采用单孔法测量土层剪切波速,该方法需要在地表人为激发剪切波,测试深度有限。本文采用自主研发的BMT-I型钻孔脉动测试设备测试钻孔脉动,分析了钻孔脉动和土层剪切波速的关系,基于地表参考点谱比法,首先对场地地表脉动及不同深度钻孔脉动数据进行分析,计算层间速度放大值;然后选取非线性拟合函数建立层间速度放大值与土层剪切波速的关系。对烟台恒大御山华府和龙湖四期工程场地进行了实测,结果表明:本文方法得到的土层剪切波速结果可为实际工程场地提供依据,与单孔法相比,该方法不需要人工激发,减少了测试人员的工作量,测试深度大大提高。

Soil shear wave velocity is an important parameter for site classification,seismic response analysis and liquefaction discrimination of saturated sand.The single hole method is often used to test the soil shear wave velocity in engineering,this method needs to stimulate shear wave artificially on the ground surface,thus the testing depth is limited.The relationship between borehole microtremor and soil shear wave velocity is studied using self-developed BMT-I borehole microtremor testing equipment:based on the surface reference point spectrum ratio method,the surface microtremor and borehole microtremor data at different depths are analyzed firstly,and the interlayer velocity amplification values are calculated;then,using the nonlinear fitting function the relationship between the interlayer velocity amplification values and the soil shear wave velocities is established.The sites of Yantai Evergrande Yushan Huafu and Longfor Phase IV Project are tested,and the results show that the soil shear wave velocity structure obtained by this method can serve in the actual engineering problems.Compared with the single hole method,the method presented in this paper does not need artificial excitation,reduces the workload,and greatly improves the test depth.