David Lally

Project Title: An Investigation of the Arching Mechanism in a Geotechnical Centrifuge.

Student Name: David Lally               

Supervisor: Dr. Patrick Naughton

Funding Body: Strand 3 to Masters Degree Level.

Abstract: Soil arching is a natural phenomenon that occurs in all granular soils as a result of a redistribution of stresses. Quantifying the amount of soil arching that occurs is a vital part of the design process for piled embankments used in the construction of roads and railways on poor soils such as peat or soft clay. The piles are driven through the unsuitable foundation soil to a firm-bearing stratum and three-dimensional soil arches develop which span the soft soil and distribute the embankment loads to the rigid piles and then the firm-bearing stratum. A geosynthetic layer is often installed over the pile caps at the base of the embankment. This further reduces the load acting on the soft foundation soil. To date none of the current design methods truly grasp the key characteristics of piled embankments.

This study aims to identify the mechanism of action in soil arching and to define and quantify the characteristics and properties of soil that influence it. Model testing in a geotechnical centrifuge will be conducted to investigate the arching mechanism and to develop a numerical model that can accurately represent the arching mechanism in piled embankment problems.