sensing, measuring and modelling the mechanical properties of sandstone

Abstract

We present a hybrid framework for simulat- ing the strength and dilation characteristics of sandstone.

Where possible, the grain-scale properties of sandstone are evaluated experimentally in detail. Also, using photo-stress analysis, we sense the deviator stress (/strain) distribution

at the micro-scale and its components along the orthogo- nal directions on the surface of a V-notch sandstone sample

under mechanical loading. Based on this measurement and applying a grain-scale model, the optical anisotropy index K0 is inferred at the grain scale. This correlated well with the grain contact stifness ratio K evaluated using ultrasound

sensors independently. Thereafter, in addition to other exper- imentally characterised structural and grain-scale properties

of sandstone, K is fed as an input into the discrete element modelling of fracture strength and dilation of the sandstone samples. Physical bulk-scale experiments are also conducted to evaluate the load–displacement relation, dilation and bulk fracture strength characteristics of sandstone samples under compression and shear. A good level of agreement is

obtained between the results of the simulations and experi- ments. The current generic framework could be applied to

understand the internal and bulk mechanical properties of such complex opaque and heterogeneous materials more realistically in future.