Abstract
The shear behaviour of bonded concrete-granite joints under constant normal stress conditions is experimentally investigated in this paper. Concrete was prepared following standard mix used in pre-existing dams in France and poured on granite samples with a natural surface roughness. Before the direct shear tests, the joint surfaces were scanned by a laser profilometer to obtain the 3D morphology features. By analysing the shear test results, no direct correlations were found between the shear strength of bonded joints and classical roughness parameter.
Highlights
The shear strength of the concrete-rock interface is a key factor in assessing the stability against sliding of concrete dams founded on rock [1]
Several experimental campaigns conducted during the last fifty years have demonstrated that several factors contribute to the shear strength of the dam-foundation interface including the joint roughness ([4], [5], [6], [7], [8]), the normal stress level, the initial bonding between the joint surfaces ([9], [10], [11]), the shear displacement rate and the mechanical properties of the joint surfaces
In order to characterise the variability in the test results and to find a potential correlation between the shear strength and the surface roughness, the maximum shear stress values were compared to different statistical parameters calculated on the joint surfaces
Summary
The shear strength of the concrete-rock interface is a key factor in assessing the stability against sliding of concrete dams founded on rock [1]. While several studies have been conducted on frictional joints ([6], [12], [13], [14]), there remains an uncertainty regarding the mechanical behaviour of bonded surfaces [16]. Except the method proposed by Grasselli [24], all the conventional techniques to assess roughness values are based on the shape of 2D profile. This can lead to inaccurate estimates of surface roughness since the joint morphology is strongly variable in space. The joints production and roughness characterization is described in a first part, the second part is devoted to the presentation of the results of shear test and in the final part an analysis of the results thanks to a upgraded roughness parameter is proposed
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