CDT-SIS-301: 1. Low cost printed pressure sensors for stability monitoring of earthworks

Standard approaches for monitoring earthwork stability involve installation of tilt sensors (inclinometers) and pore water pressure sensors into boreholes. The need to drill boreholes to install these at some depth makes them costly to install. Low-cost condition monitoring using near-surface sensors over long lengths of railway earthworks is very desirable, but there remain significant challenges to the reliability of such a system.

The project will investigate embedding low cost and rugged thick film (TF) pressure sensors in earthworks to see if they can detect changes in soil displacement and/or total earth pressure (as opposed to pore water pressure), that could indicate earthwork displacement (or even the potential for displacement) in cuttings and embankments. Key features of TF pressure sensors are their ability to sense direct (earth) pressure (z axis effect) as well as strain due to buckling (XY effect) resulting from relative displacements. It is also possible through innovative design and careful placement of individual sensing elements on a single substrate to discriminate between these different force components. A key part of the project will be in trying to determine the extent to which any detected changes in sensor outputs (due to pressure changes or soil displacement) are indicative of earth movement or incipient movement. It is anticipated that gross, sudden or abrupt changes in sensor output are very likely to result from actual displacement of earthworks but it is also an aim of the project to try to establish whether sensor output changes can also be indicative of the likelihood of displacement occurring (such as differential pressure e.g. changes in readings recorded at the top and bottom of slopes).

The project will: i) design and print suitable TF sensors; ii) test them in the laboratory using soil column and sandbox tests; iii) install sensors in a real slope(s) to test their practical ability, supported by Network Rail; and iv) suggest a framework in which the sensors can be used to assess the risk of slope failure based on known properties (geometry, soil type, vegetation cover) of the earthwork. The student will build on the EPSRC iSMART project, which is investigating failure and risk of failure within infrastructure earthworks.

This project is being run in participation with the EPSRC Centre for Doctoral Training in Sustainable Infrastructure Systems. For details of our 4 Year PhD programme and further projects, please see http://www.cdt-sis.soton.ac.uk/