Bender element test in soil specimens: identifying the shear wave arrival time

Chee-Ming , Chan (2011) Bender element test in soil specimens: identifying the shear wave arrival time. Geotechnical and Geological Engineering . pp. 1-8. ISSN 0960-3182

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Official URL: http://ejge.com/2010/Ppr10.098/Ppr10.098.pdf

Abstract

Bender elements have become more and more commonly used for measuring the shear wave velocity in soil specimens with the purpose of estimating the small strain shear modulus (Gn) of the material. A pair of in-line bender elements is usually used where one acts as the transmitter sending off the shear waves, while the other on the opposite end captures the arriving waves. The shear wave velocity (vs) is derived by dividing the travel distance of the waves (between the transmitter and receiver) with the arrival time which in turn is squared and multiplied with specimen's bulk density obtain Go (on assumption of a plane wave traversing a homogeneous and elastic material). Nevertheless the shear wave arrival time determined from bender element measurements can vary over a wide range, depending on the method adopted to identify the arrival time. This paper describes a series of bender element tests conducted on a pair of unconfined specimens i.e both measuring 80mm in height, 76mm and 114mm in diameter respectedly. With shear waves triggered at frequencies between 7 and kHz the received signals were subjected to careful examination of the arrival time, in both time and frequency domains. Interestingly no one method turned out as the winner where each presented certain problems and discrepancies. The time domain method remained favorable due to its simplicity which is perhaps one of the key factors contributing to the growing popularity of bender elements. The frequency domain method on the other hand involved complex manipulation of the original signals which can be onerous and time-consuming. In conclusion as far as bender elements are concerned the reliability of shear wave velocity measurements can be significantly increased of the user rigorously employs the same arrival time identification method and exercises consistent judgement in the test series.

Item Type:Article
Uncontrolled Keywords:shear wave velocity; unconfined specimens: small strain shear modulus; bender element: arrival time
Subjects:T Technology > TA Engineering (General). Civil engineering (General) > TA703-711 Engineering geology. Rock mechanics. Soil mechanics.
ID Code:3870
Deposited By:Normajihan Abd. Rahman
Deposited On:25 Jul 2013 12:59
Last Modified:22 Jan 2015 08:36

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