Studies on the determination of shear wave velocity in sands

Abstract

Laboratory investigations such as resonant column, cyclic triaxial, and torsional shear tests are usually conducted on undisturbed and reconstituted sand samples in order to determine their shear modulus, which can be used to compute shear wave velocity. However, these methods are extremely cumbersome and indirect, they employ cost-intensive instrumentation, and they require trained manpower. These problems can be overcome by using bender elements, which yield the shear wave velocity of sands directly, easily, and quite rapidly. In this context, efforts made by earlier researchers in developing empirical relationships (based on bender elements and resonant column techniques) which can be employed to compute shear wave velocity in sands are worth consideration. Although these relationships take into account parameters like effective stress and void ratio, they do not directly incorporate fundamental characteristics of sands such as their state (i.e. dry or saturated) and the particle size. Thus a generalized relationship, which can be used to compute shear wave velocity in sands in either the dry or saturated state, has been developed. Experiments were conducted on samples of sand and glass beads of different sizes and the results were used to demonstrate the utility and efficiency of the relationship. Details of the methodology developed for this purpose are also presented in this paper.

Keywords:

• Shear wave velocity
• Sand
• Bender elements
• Resonant column
• Generalized relations

Notes

Ortiz, O. F. P., Small and large strain monitoring of unsaturated soil behavior by means of multiaxial testing and shear wave propagation. Ph.D. thesis, Louisiana State University and Agricultural and Mechanical College, 2004.