The large column experiment was implemented as part of the GMT experiment. The objective was to provide a medium-scale experiment to calibrate the TDR probes (link to TDR Measurement Principle) applied in the GMT in-situ experiment. The sand-bentonite (S/B) mixture (80% sand and 20% Japanese Kunigel) was emplaced with the same density and with the same initial saturation as the GMT experiment. The experiment is running since 2002 and thus provides one of the longest records of sand-bentonite behaviour during the saturation phase on a decimeter scale.

The experiment now continues within the framework of the FORGE project with the main aim to investigate the gas entry pressure into fully saturated S/B. The main steps of the experiment are listed in the table below.

Date  Work item
Mar 2002  Start water injection at 20 bar pressure
Jan 2008  Change injection to He backpressure
Jan 2008  Add fluorescein to injection water
Nov 2008  Increase outflow pressure to 15 bar (5 bar delta presssure)
Feb 2012  Start gas injection


FORGE Laboratory Column Experiments at grimsel: Large TDR column experiment

Laboratory Column Experiments (FORGE)