Particle-Scale Investigation of Seepage Induced Geotechnical Instability
Civil engineering works often encounter water flowing through the ground. Important examples include embankment dams (such as used for hydroelectric pumped-storage), flood walls and embankments.
Summary
Awareness is growing that seepage forces imparted on individual particles can preferentially erode the smaller particles in sandy soils. There can be significant internal erosion of the soil under scenarios that are considered safe according to the classical continuum calculations used in engineering practice; this phenomenon is called internal instability. This cross-institutional proposal combines experimental expertise in testing transparent soil at the University of Sheffield (UoS) with skills in discrete element modelling (DEM) at Imperial College London (IC).
The research seeks to clarify: (i) Which materials are initially susceptible to internal instability (including influence of particle shape and size on interstitial fluid behaviour and flow structures), and transitions between suffusion (no volume change) and suffosion (with volume change). (ii) Whether seepage velocity or hydraulic pressure gradient correlates better with the initiation of erosion. (iii) How the stress level influences susceptibility; particularly considering stress anisotropy and the relation between principal stress orientation and seepage direction. The tools used at Sheffield comprise a transparent soil permeameter to visualise internal soil behaviour (via 2D plane laser tomography) along with particle and fluid tracking and a triaxial stress path cell with erosion measurement.
Sponsor
Engineering and Physical Science Research Council (EPSRC)
Project dates
Start date: 01/04/2017
End date: 31/03/2020
People involved
- Dr Elizabeth Bowman
- Dr Jonathan Black
- Nicoletta Sanvitale (PDRA)
- Fahed Gaber (PhD)