Correlation of Texas Cone Penetrometer Test Values and Shear Strength of Texas Soils

PROJECT PI and Co-PIs

Dr. C. Vipulanadan, Professor, Department of Civil and Environmental Engineering, University of Houston

Dr. A. J. Puppala, Professor, Department of Civil and Environmental Engineering, University of Texas at Arlinton

Dr. Mien Jao, Professor, Department of Civil and Environmental Engineering, Lamar University

SHORT DESCRIPTION

In this study, Texas Cone Penetration test data of both field and laboratory tests conducted by the Texas Department of Transportation (TxDOT) were collected, compiled, analyzed, and synthesized to create a database. Based on this database, correlation equations between blow-count and shear strength parameters were developed. In the development, the bearing capacity theory for low plasticity clay (CL soil) was adopted. The effectiveness of the new correlations was evaluated by comparing with what is currently being used by TxDOT.

jao_proj_2

FULL DESCRIPTION

Texas Cone Penetration test is a primary in-situ field test method for determining the shear strength of soils by the Texas Department of Transportation. For geotechnical analysis and foundation design, the available correlations between undrained cohesion and cone penetration blow count are not very effective for some soil and field conditions. In an attempt to compare/improve/refine the available correlations, this study was undertaken to investigate the effect of depth on cohesion vs. blow count relations. Based on the basic bearing capacity principle together with the statistical regression approach, the effect of depth on cohesion vs. blow count relation was developed. The TxDOT correlation was found to be close to the developed correlations for depths ranging between 15 ft (4.57 m) and 25 ft (7.62 m). It is concluded that the developed correlations with depth effect would be a good approach for improving the correlation currently used by TxDOT for geotechnical analysis and foundation design. However, it is recommended that more studies should be conducted in other types of soils in other TxDOT districts.

FUNDING

Funded by Texas Department of Transportation