Identification of Soil Stratigraphy of Soft Deposit in Shanghai from CPTU Test

Abstract

This paper presents a well recorded case history of cone penetration test with pore water pressure measurement (CPTU) in the soft deposit of Shanghai. In China, stratigraphy for soft deposit is obtained through physical properties (e.g. grain size and color) and mechanical properties (e.g. cohesion and inner friction angle from direct shear test) from borehole samples. Identification of soil stratigraphy with CPTU was developed 30 years ago. The field data at test site of Yan’an Road Tunnel in Shanghai is used in the analysis. The soil classification chart proposed by Robertson is employed to identify soil strata. The results are compared with that from plasticity index and grain size distribution of borehole samples (refer to code method). The results show that Robertson’s chart can identify the stratigraphy of the soft deposit in Shanghai. However, there are some discrepancies of the results from Robertson’s chart and the code method. The reason of the discrepancies is also discussed in the paper.