Zhang, H & Akutagawa, S 2015, 'A mechanical method for monitoring and data visualisation of small deformations in underground structures', in PM Dight (ed.), FMGM 2015: Proceedings of the Ninth Symposium on Field Measurements in Geomechanics, Australian Centre for Geomechanics, Perth, pp. 329-338, https://doi.org/10.36487/ACG_rep/1508_20_Zhang
(https://papers.acg.uwa.edu.au/p/1508_20_Zhang/)
Abstract: In recent years, an onsite visualisation method was proposed to measure the deformation of structure and to visualise the measured results by different colours of light in real time for personnel conducting field measurement. Based on this concept, a mechanical method is introduced in this paper to monitor the small deformations in underground structures such as cracks in the concrete lining of a tunnel. It consists of a rotational structure which is used to transform the linear relative displacement into the movement of rotation. The other component is a small mirror which is mobilised to rotate by the rotational structure. An observer can see the reflected image of the coloured mark in the mirror from a certain distance. If the mirror rotates when displacement happens, the reflected image of the mark would move at the same time and eventually disappear from the mirror. As a result, the displacement can be identified visually by the changing reflected image of the coloured mark and its value can be read directly from the width of the shifted mark. The mirror size and the distance between the observer and the mirror determine the precision of the method for measurement. In this paper, the fundamental experiments were carried out to verify the feasibility and effectiveness of the method. The authors believe that this mechanical method could improve the safety management of tunnelling, mining and rock slope engineering.