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为了给南京长江四桥基础工程设计与分析提供可靠的长江漫滩粘性土不排水抗剪强度Su参数,采用国外引进的孔压静力触探(CPTu)测试系统进行了现场原位试验,并以高质量土样的室内试验作为参考,对几种基于CPTu的Su确定方法进行了对比与评价,同时对所提出的圆锥系数Nk值进行了验证.试验结果表明:圆锥系数Nkt,Nke,NΔu的大小取决于剪切试验模式及试验扰动程度;Nke一般比Nkt,NΔu表现出更大的离散性;对于长江漫滩多夹层粘土地基,建议采用净锥尖阻力qt预测Su,相应的圆锥系数Nkt数值在7～16之间,平均值为11;应用CPTu新技术,可以为桥梁基础工程设计提供合理的设计参数.
In order to provide reliable undrained shear strength Su parameters of the Yangtze River floodplain for the design and analysis of the four-bridge foundation engineering in Nanjing, in situ test was conducted by using the CPTu test system imported from abroad Based on the indoor test of high quality soil samples, several methods for determining Su Su based on CPTu were compared and evaluated, and the proposed Nk value of cone coefficient was verified.The experimental results show that the conic coefficients Nkt, Nke, NΔu The size depends on the shear test mode and the degree of experimental disturbance. Nke generally shows more dispersion than Nkt and NΔu. For the multi-layered clay foundation in the Yangtze River floodplain, it is recommended to use the net tip cone resistance qt to predict Su and the corresponding conic coefficient The Nkt value is between 7 and 16, with an average value of 11. The new CPTu technology can provide reasonable design parameters for the bridge foundation engineering design.