Experimental investigation and numerical modeling of piezoelectric bender element motion and wave propagation analysis in soils

Abstract

The bender element (BE) test has been widely used for the dynamic characterization of soil specimens at low-shear strain levels. However, the actual behavior of the BE inside a soil specimen remains unknown. Thus, the current ASTM standard does not consider the interference of compressional and shear waves in BE testing, which can lead to significant errors in the evaluation of shear wave velocities. The main objective of this paper is to present a numerical model of the BE system to better understand the response of the BEs inside a soil sample. The model is calibrated, verified, and then used to demonstrate the importance of taking into consideration the interaction between compressional and shear waves for the correct interpretation of BE measurements. The model successfully captured the measured vibrations of the BE in air as well as inside transparent soils. More importantly, the numerical simulations provide a new understating of the significant interactions of P-waves and S-waves especially in clay soils. Thus, the proposed coupled piezoelectric and solid mechanics model can be used to study the soil-BE interaction so that sound recommendations can be given to improve the interpretation of BE tests in different soils.