Application of Piezocone Penetration Test and Flat Dilatometer Test in Shanghai Soft Clay

Based on the geotechnical engineering survey project of Shanghai Rail Transit Airport connecting line, the piezocone penetration test and flat dilatometer test were carried out, and the high-quality sampling compression test results were obtained. The effects of different tests and different chart classification methods on the classification effect were studied, and the relationship between flat dilatometer test and over consolidation ratio, cone tip resistance and compression modulus were analyzed. The results show that the chart method of pore pressure static cone penetration test has a good classification effect on Shanghai soft clay, but it is not ideal for transition soil (silt) and "mixed soil", and the classification method of flat dilatometer test can achieve a good classification effect. The soft clay is overconsolidation soil while the burial depth is less than 18.0 m in Shanghai area. Its overconsolidation ratio decreases with the depth increase, and the soft clay is normally consolidated soil while the burial depth is greater than 18.0 m. For different types of soft clay, there is an obvious linear correlation between cone tip resistance and compression modulus, which can be expressed by a unified formula.