The engineering properties of old tipped clay fill earthworks
Joel Smethurst (Infrastructure)
Most railway embankments in the UK were built in a period between 1835 and 1860, making them now around 170 years old. These older embankments were nearly always end-tipped; this involved constructing the earthwork to its full height by simply tipping material off the end of the advancing embankment. The embankment fill was little compacted, resulting in large settlements and sometimes embankment failure not that long after construction. The fill material came from the nearest areas of cut, and depending on the local geology was highly heterogeneous, including for example a mix of clays, sands and rock. Today, old clay earthworks are particularly problematic, and can be prone to deep-seated slope failures that disrupt railway operations. The old clay fill materials often have a structure, with large (100 – 300 mm) clods of intact material surrounded by a probably less dense matrix of more heavily reworked soil. This structure influences the engineering properties of the old tipped clay fills, including their permeability, strength and stiffness, which can all effect the performance of the earthwork. The PhD project will investigate the fill structure and its impact on the strength, stiffness and permeability of the fill, using large block samples excavated from old tipped clay fill railway embankments. This will involve use of an industrial X-Ray CT to study the fill structure, and a range of soil mechanics tests including high quality triaxial testing to determine the strength and stiffness of different components of the fill (clod and matrix). There may also be opportunities to extend the 3D CT volume and experimental results into numerical simulations that help to understand the bulk behaviour of the fills.
300 mm cube block sample taken from a Weald Clay railway embankment at Edenbridge, Kent
Key skills: Experimental, data analysis, modelling
Industry partners: Access to soil samples will be supported by Network Rail
Eligibility: UK rates (subject to fund availability)
Start date: October 2023 (subject to fund availability)
Application deadline: August 2023
CIVIL, MARITIME
AND ENVIRONMENTAL
ENGINEERING DEPARTMENT
University of Southampton
Explore our website:
Contact us:
+44(0)23 8059 5000
+44(0)23 8059 3131
University of Southampton
University Road
Southampton
SO17 1BJ
United Kingdom
CIVIL, MARITIME
AND ENVIRONMENTAL
ENGINEERING DEPARTMENT
University of Southampton
Explore our website:
Contact us:
+44(0)23 8059 5000
+44(0)23 8059 3131
University of Southampton
University Road
Southampton
SO17 1BJ
United Kingdom
© 2020 Civil, Maritime and Environmental Engineering Department
© 2020 Civil, Maritime and Environmental Engineering Department