Bender Elements and Bending Disks for Measurement of Shear and Compression Wave Velocities in Large Fully and Partially Saturated Sand Specimens

Bender element and bending disk setups were designed and implemented in a liquefaction box that accommodated a large sand specimen (190 mm × 300 mm × 490 mm). The box was manufactured for testing fully and partially saturated sand specimens under cyclic and earthquake excitation. Special housings for bender elements (31.8 mm × 12.7 mm × 0.51 mm) were manufactured to allow insertion of the elements through the side walls of the box. The bender elements were used to measure shear wave velocities in multiple directions to ascertain the uniformity of a sand specimen prepared in the liquefaction box. Large bending disks (31.8 mm × 0.41 mm) in special housings were utilized to measure compression wave velocities with the aim of investigating the presence and effect of the degree of partial saturation in specimens. The housings for bender elements and bending disks were designed to minimize the boundary effects of the Plexiglas walls of the liquefaction box. This paper provides details of the experimental setup and the designs of the bender element and bending disk housings. Sample test results of shear and compression wave measurements are also included to demonstrate successful application of the test setup. The experimental setup described is well suited for utilizing bender elements and bending disks for shear and compression wave velocity measurements in fully and partially saturated large sand specimens.