单孔波速测试在杭州某岩土工程勘察中的应用

Application of Single Hole Wave Velocity Test in the Geotechnical Investigation in Hangzhou

使用地球物理方法,为杭州某工程建设项目提供了场地抗震设计依据。根据该场地地质条件,现场共布置试验钻孔4个,进行原位单孔波速测试。得到了4个钻孔的原始波形图,进而得到各钻孔在深度范围内各土层剪切波速度分布情况,计算各钻孔平均土层等效剪切波速,建立各钻孔在测试深度范围内深度与剪切波速度的关系曲线,判别地基土类型、场地类别及抗震设防烈度等。根据判断分析表明,该场地土类型为中硬土,建筑场地类别为Ⅰ_(1)~Ⅱ类,抗震设防烈度为6度,设计地震分组为第一组,特征周期Ⅰ_(1)类场地为0.25 s,Ⅱ类场地为0.35 s。勘察实践表明,单孔波速测试可直接对地层测试、结果相对精确且方便快速。

The geophysical method was used to provide the seismic design information of a project in Hangzhou.According to the site geological conditions,a total of four(4)test borings with the in-situ single-hole wave velocity test were planned and the original waveform figures within different soil layers were obtained.The average shear wave velocity in different soil layers and the thickness of each soil layer were determined.The seismic site class and the seismic design intensity could be established based on the obtained seismic shear wave velocity.The results indicate that,the project site class belongs to I1 to II and the seismic design intensity is six degrees.The design seismic group belongs to the first group,and the characteristic period of the site category I1 is 0.25 s,the site categoryⅡis 0.35 s.The investigation results also show that the single-hole wave velocity test could be directly used in the site geophysical testing,and the result is relatively accurate and convenient.