Title : Effects of weathering on the small strain behaviour of decomposed volcanic rocks

Page : PP.97-107

Author(s) : Ismail Adeniyi Okewale

Keyword : stiffness, bender elements, Weathering, structure, volcanic saprolites

Abstract : 

In this study, the effects of weathering on the stiffness characteristics and small strain behaviour of decomposed volcanic rocks were investigated in detail. Few studies exist on the small strain behaviour of weathered materials and the studies on geomaterials resulting from decomposition of volcanic rocks are very scarce. The study investigated the small strain behaviour of decomposed volcanics in the reconstituted and intact states, allowing for the effect of structure. This was achieved by carrying out extensive triaxial tests using multi-directional bender elements and high resolution linear variable differential transformers on the samples of various degrees of weathering from different locations, depths and formations. Elastic model parameters obtained from experimental data are used as stiffness parameters and they are related with engineering indices and depth which is very important from geological point of view. The effect of heterogeneity is much more obvious at small strain. The effect of structure is generally small using bender elements at small strain. Weathering affects the stiffness of decomposed volcanic rocks and more effect is seen particularly for the reconstituted samples. Plasticity and fines content might be controlling parameters for the stiffness of decomposed volcanics

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