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Graphical abstract Highlights • Layered soil materials are characterised using different techniques. • Failure patterns of layered soil systems are analysed using DPIV. • A correlation between the slip surface angle β and H/B is presented. • A good level of comparisons between the DPIV and FEM results. • A new methodology is proposed to estimate UBC of layered soil. Abstract In the geotechnical and terramechanical engineering applications, precise understandings are yet to be established on the off-road structures interacting with complex soil profiles. Several theoretical and experimental approaches have been used to measure the ultimate bearing capacity of the layered soil, but with a significant level of differences depending on the failure mechanisms assumed. Furthermore, local displacement fields in layered soils are not yet studied well. Here, the bearing capacity of a dense sand layer overlying loose sand beneath a rigid beam is studied under the plain-strain condition. The study employs using digital particle image velocimetry (DPIV) and finite element method (FEM) simulations. In the FEM, an experimentally characterised constitutive relation of the sand grains is fed as an input. The results of the displacement fields of the layered soil based DPIV and FEM simulations agreed well. From the DPIV experiments, a correlation between the slip surface angle and the thickness of the dense sand layer has been determined. Using this, a new and simple approach is proposed to predict theoretically the ultimate bearing capacity of the layered sand. The approach presented here could be extended more easily for analysing other complex soil profiles in the ground-structure interactions in future. [ABSTRACT FROM AUTHOR]

Mechanical behaviour of powders and grains often displays features of solid-like and liquid-like characteristics of matter. In spite of processing granular materials quite extensively in the industries, their flow behaviour is still complex to understand under different process conditions. In this paper, using digital particle image velocimetry (DPIV) and high speed videography, we probe systematically on the spatial and temporal distributions of the velocity fields of pharmaceutical excipient granules flowing though smooth hoppers with different internal (orifice) angles. This helps to visualise and identify the locations and formation of the flow channels and conversely the stagnation zones of granular materials inside the hoppers as a function of the internal angle of the hoppers. We show that even when a powder characterised as a free-flowing type in the conventional sense could experience a significant level of hindrance to flow even when passing through smooth hoppers of different internal angles, and its impact increases with an increase in the internal angle. Theoretical predictions are made using experimentally evaluated grain-scale properties as input parameters for understanding the effects of hopper angle on the granular flow rate. A good level of agreement is obtained between the experimental and theoretical estimates of the granular flow rate in terms of the hopper angle. The outcomes presented here are a step forward in designing granular flow devices more efficiently in the future. [ABSTRACT FROM AUTHOR]