A Modified Rowe Cell with Bender Elements for Small Strain Shear Modulus Measurements

Abstract

Abstract The small strain shear modulus (G0) is an important characteristic of geomaterials. Its laboratory measurements are very frequently based on bender element transducers installed in different geotechnical apparatuses. Despite their widespread use, there is room to improve the precision, reproducibility, and robustness of bender element measurements, which are currently hampered by an oversimplified interpretation model of the test. Aspects such as transducer directivity, apparatus-induced size effects, and boundary reflectivity are poorly understood and accounted for. This work presents a novel modified Rowe cell apparatus specifically designed to obtain experimental data relevant to those features. The modified Rowe cell uses transmitter and receiver bender elements on the same boundary of the sample, performing dynamic measurements in echo mode with variable initial specimen size. Additionally, the modified Rowe cell endorses the flexible installation of the receivers and enables the use of multiple receivers, with distinct orientations. Furthermore, the modified Rowe cell gives the option of using different boundary conditions at the reflecting end to test the dynamic properties of usual geotechnical testing apparatus interfaces such as (semi-) rigid enclosures and flexible membranes. A systematic reliability study of the bender element measurements on the modified Rowe cell is presented, along with some illustrative examples of the capabilities of the apparatus.