基于CPTU解释黏性土不排水抗剪强度方法研究

黏性土的不排水抗剪强度Su是海上风电工程设计中重要的力学参数之一，孔压静力触探测试（简称CPTU）无法直接测得黏土强度，但其所提供的锥尖阻力、侧摩阻力以及孔隙水压力与土体的不排水抗剪强度存在映射关系，国内外基于CPTU已经演化出多种解释土体不排水抗剪强度计算公式。基于滨海某海上风电项目，开展了原位CPTU试验、三轴不固结不排水（UU）、三轴固结不排水（CU）、固结快剪（CQ）以及船上微型十字板剪切（MVST）试验，对已有计算公式的适用性进行了校验，分析发现需根据区域场地情况对其中经验系数进行相应的调整以提高计算精度。研究基于CU试验结果，结合工程实例对原有公式中经验参数进行优化修正，最后通过误差分析，验证了修正预测模型的准确性与合理性，利用改进后的修正预测模型可使江苏地区海域黏性土不排水抗剪强度的计算得到更准确的结果。

Estimation of the undrained shear strength of cohesive soil using CPTU intrepretation

The undrained shear strength Su of cohesive soil is one of the crucial mechanical parameters in the design of offshore wind power projects. The piezocone penetration test (CPTU) cannot directly measure the strength of cohesive soils, but the cone tip resistance, side friction resistance and pore water pressure provided by it have a mapping relationship with the undrained shear strength of soils. A variety of calculation formulas have been developed at home and abroad based on the CPTU interpretation of soil undrained shear strength. Based on an offshore wind power project in Binhai, in-situ CPTU tests, triaxial unconsolidated-undrained (UU) tests, triaxial consolidated undrained (CU) tests, consolidation quick shear (CQ) tests and miniature onboard vane shear (MVST) tests were carried out to check the applicability of the existing calculation formulas. It was found that the empirical coefficients needed to be adjusted accordingly to improve the calculation accuracy according to the regional site conditions. Further, based on the results of the CU tests, the empirical parameters in the original formula were optimised and modified in conjunction with engineering examples. Finally, through error analysis, the validity and accuracy of the revised prediction model are verified, which can provide more accurate results for the calculation of the undrained shear strength of cohesive soils in the sea area of Jiangsu Province.