The Effect of Different Boundary Conditions on the Result of Bender-Extender Element Test

摘要

Bender-extender element tests have been commonly used in a laboratory to obtain shear wave velocity and compression wave velocity of soils. There are obvious advantages of bender-extender element test method, e.g. its apparent simplicity and ease of use. However, there is still no unified standard for the test because the reliability of result is affected by a number of factors. In this study, the effects of boundary conditions on measurement of shear wave velocity and compression wave velocity of soils in bender-extender element test are investigated. In order to compare compression wave velocity of distilled water and shear wave velocity of dry sand, a series of calibration tests are performed by varying boundary materials, heights, and wall thickness of the sample constraints. It reveals that the compression wave velocity of distilled water does not be affected by the boundary conditions of sample, but the experimental results of shear wave velocity of dry sand are indeed affected by boundary conditions and the excitation frequency of bender-extender element.