地基基础与建筑场地类别划分

基于与建筑地基震害密切相关的地基土性状及基础条件,讨论了岩土工程勘察设计工作中关于场地土和建筑场地类别划分的主要依据,提出了对我国现行《建筑抗震设计规范(GB50011 2001)》进行基础埋深、覆盖层厚度和复合地基的地基土性状的修正, 并经场地土层地震反应分析论述了进一步划分建筑场地类别的必要性和可能性。以北京的2个典型工程场地为代表,分别讨论了基础埋深和覆盖层厚度对建筑场地类别划分的影响,并通过场地土层地震反应分析,得到自然地面上、基础埋深处土层的反应谱,同时也计算了在考虑或不考虑低速粘性土夹层情况下对土层地震反应结果的影响程度。最后,根据综合峰值加速度、加速度反应谱最大值的对比结果认为对原有的建筑场地类别划分方法有必要进行修正。

The Foundation and Categorization of Building Sites

This paper discusses the fundamentals of categorization of building sites based on the behaviors and conditions of foundation soils correlated with earthquake disasters of foundation in geotechnical investigation design, suggests revising the foundation embedment and the depth of overburden and the behavior of foundation soil according to the current "Code for Seismic Design of Buildings" (GB 50011-2001) of China, and emphasizes the necessity and possibility of further categorization of building sites using seismic response analysis of soil layers at the site. The paper has also analyzed the influence of the foundation embedment and the depth of overburden on building site categorization respectively with 2 typical project sites in Beijing, and then applied the seismic response analysis of soil layers (the input waves are taken as artificial seismic waves with different exceeding probabilities) to obtain the response spectrum on ground surface and 23m-depth subsurface, calculated the degree of influence on the result of soil layer response taking account or no account of clay and soil interlayer, and finally integrated the comparisons between peak acceleration and the maximum acceleration response spectrum values to revise the building site categorization.