Publication Details

Indraratna, B., Premadasa, W., Nemcik, J. & Jayanathan, M. (2012). Shear strength model for sediment-infilled rock discontinuities and field applications. In G. A. Narsilio, A. Arulrajah & J. Kodikara (Eds.), 11th Australia - New Zealand Conference on Geomechanics: Ground Engineering in a Changing World (pp. 1250-1255). Australia: Engineers Australia.


Discontinuities have a great influence on the reduction of rock mass shear strength depending on the geometry, roughness and the nature of infill sediments. These discontinuities are generally filled with different types of sediments. When the infill sediments are saturated, they make a considerable impact on the overall strength of the rock mass. Most infilled discontinuities in the field are overconsolidated due to various factors such as climatic and weathering conditions, as well as hydrothermal alteration. The increase in the thickness of joint infill subdues the otherwise prominent role of joint roughness. This paper presents some of the existing mathematical models for predicting the shear strength of sediment-infilled rock joints and modification to the shear strength model for overconsolidated infill joints considering energy balance principles to better predict the clean joint strength. A simplified approach for using this model in practice is presented through a hypothetical example of slope stability, and use of the model to predict safety factor of a slope under different overconsolidation ratios of infill is discussed. An analysis to stabilise a potentially unstable rock slope using pre-tensioned fully grouted bolts is also presented.

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