Piezoelectric probe for measurement of soil stiffness

Abstract

Measurement of in situ soil properties is imperative for pavement design. The stiffness and Poisson's ratio of base and sublayers are essential factors in the design and quality control of compaction during construction of highway pavements. It is critical to have a portable and mechanised system to measure these parameters in situ. Currently used techniques including California bearing ratio, resilient modulus, dynamic cone penetrometer and falling weight deflectometer have limitations preventing compliance with requirements for the design of highway pavements. A new device implementing a geophysical probe equipped with piezoelectric sensors to measure the soil properties has been developed. Initial laboratory testing has been performed. The techniques for measuring soil stiffness are discussed, emphasising bender and extender element applications. Data acquired from the new device are compared with the results of an empirical formula developed by Hardin and Richart. Representative test results demonstrating the device performance are discussed.

Keywords:

• bender element
• constrained modulus
• extender element
• piezoelectric probe
• Poisson's ratio
• shear modulus

Acknowledgements

The research work reported here was supported by a contract (NHERP-112) from the National Research Council of National Academy of Science. The authors would like to thank Dr Jawed, the program manager, for his support throughout the project. The project was also supported by a grant from the Ohio Department of Transportation. The first author would like to thank the Transportation Research Board for the support of this project through the Eisenhower Fellowship.

Notes

^1. [email protected]

Additional information

Notes on contributors

H.A. Hlasko

1. 1. [email protected]