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针对南京长江四桥漫滩沉积土,分别进行了室内试验和多功能地震波孔压静力触探(SCPTU)原位测试,从SCPTU应用于场地复杂地层的精细划分、长江漫滩沉积黏性土透水性能的评价和预测渗透系数kh 3个方面进行了详细分析,试验结果表明:综合利用多功能SCPTU测试qt、fs、u2 3个参数可以对具有高度分层性和不均匀性的长江漫滩沉积土进行精确分层,对不同性质土层界面、同一土层内透水或不透水夹层进行精确探测;利用SCPTU钻进过程中的孔压消散试验功能,可以对复杂的混合土层的透水性能进行评价;基于SCPTU的渗透系数kh预测值均具有一定的离散性,一般比室内试验结果高1~2个数量级,Burns&Mayne方法预测值可以作为工程初设阶段的参考值;SCPTU的应用为基坑工程降水设计提供了一种简便、快捷的新型技术手段。
In-situ tests and multi-purpose seismic wave porous pressure static seepage test (SCPTU) were carried out for the sediment in the floodplain of the Fourth Bridge over the Yangtze River in Nanjing. SCPTU was applied to the fine division of the complex formation in the site, Permeable performance evaluation and prediction of permeability coefficient kh three aspects were analyzed in detail, the test results show that: comprehensive use of multi-function SCPTU test qt, fs, u2 three parameters can be highly layered and inhomogeneous Yangtze River floodplain Sedimentary soil is stratified accurately to accurately detect water-permeable or water-impermeable sandwiches in the interface of different soil layers and in the same soil layer. By using the function of pore-pressure dissipation test in SCPTU drilling, the water permeability of complex mixed soil layers The predictions of permeability coefficient kh based on SCPTU are all discrete. They are generally 1 to 2 orders of magnitude higher than the indoor test results. The predicted value of Burns & Mayne method can be used as reference for initial stage of project. The application of SCPTU as foundation pit Engineering precipitation design provides a simple, efficient and new technical means.