Projekt

Maximum gradient and repetitive Hydraulic load effects on suffusion of glacial till cores

Uppdaterad 2023-09-21 Publicerad 2021-09-22

The research consists on an experimental investigation of the effects of hydraulic loading on the initiation of internal erosion by suffusion in glacial till dam cores. The main experimental variable is the hydraulic gradient, which is applied both as a constant load and as an incremental load. Other variables included in the study are the soil density and its particle size distribution. The boundary test condition defined by the open size of the filter is also included. The definition of all mentioned parameters intents to simulate potential in-situ conditions in Swedish dams.

Results shows that, regardless of the density, the internal stability of well-graded till soils is not significantly affected by hydraulic gradients increased stepwise; thus this type of soil are unlikely to be susceptible to suffusion. Gap-graded soils instead can be affected by suffusion when poorly compacted and exposed to hydraulic gradients applied both as a constant load and as a load increased stepwise. Although a clear relation between the rates of increase of hydraulic gradient and its impact on the initiation of suffusion have not been found, it was noticed that the most significant sign of suffusion (variation of hydraulic conductivity) occurs during the first increments of hydraulic gradient.

Results
Results are to compiled in an approach that could be applied in the safety assessment of dams with glacial till core.

Om projektet

Projektledare

Jan Laue, Luleå tekniska universitet

Doktorand

Ingrid da Silva, LTU

Projektdeltagare

Peter Viklander, Vattenfall/LTU
Qi Jia, LTU
Jenny Lindblom, LTU

Publiceringar

On the experimental investigation of suffusion and critical hydraulic gradients in granular soils. (under granskning)

Effects of the increase of hydraulic gradient on internal erosion of glacial till soils.

Factors affecting suffusion test of glacial till dam cores. (under granskning)

I. Silva, P. Viklander, and J. Laue, ‘Effects of hydraulic load on suffusion of glacial till soils’, presented at the 20th International Conference on Soil Mechanics and Geotechnical Engineering (ICSMGE 2022), 2022.

I. Silva, P. Viklander, and J. Laue, ‘On the boundary conditions of suffusion tests and its relation to dam safety’, presented at the 7th International Young Geotechnical Engineers Conference (7iYGEC 2022), 2022.

I. Silva, P. Viklander, and J. Laue, ‘Effects of Void Ratio and Hydraulic Gradient on Permeability and Suffusion of Glacial Till Cores’, in Internal Erosion in Earthdams, Dikes and Levees: Proceedings of EWG‐IE 26th Annual Meeting 2018, 2018, pp. 98–109.

I. Silva, ‘Suffusion of Glacial Till Dam Cores : An Experimental Investigation’, Licentiate dissertation, Luleå, 2019.

I. Silva, ‘Investigation of Suffusion in Glacial Till Dam Cores: Testing methods and critical hydraulic gradients’, PhD dissertation, Luleå University of Technology, Luleå, 2021.

Tid

april 2018 - december 2020