Gas-Permeable Seal Test - Water Injection Phase

The sand/bentonite seal has been saturated through the sand filter on the side of the concrete plug:

  • Phase I - Saturation of the injection filter (11th  – 17th July 2012) 
  • Phase II - Pressurization Phase: The pressure was increased in steps until a manometric height of around 3.5 m was reached (17th July 2012 – 29th April 2013)
    The pressure was increased in steps until a manometric height of around 3.5 m was reached
  • Phase III - Saturation Phase (29th April 2013 – 29th January 2014). A rate injection is performed
  • Leak event (28th January 2014)
  • Depressurisation and remediation (29th January 2014 – June 2015)
  • Phase VI – Remediation and Resaturation (July 2015)

gast water saturation
Longitudinal cross section of the GAST experiment with instrumentation sections Sxx and levels Lx (not all sections and levels shown). Superposed is a vertical section of interpolated pore pressures as observed on 31.12.2013.

gast water saturation results

a) Injection phases and water flow, b) head space relative humidity, c) S/B pore pressure, d) total pressure at tunnel surface. Sensor code in legends: [Sensor type]_[Section]_[Level] (see figure above for positions).

Gas-Permeable Seal Test (GAST)

The GTS underground facilities are also available to interested 3rd parties for underground testing and research. The GTS offers cost-effective access to a fully developed, well characterised underground research facility with round the year logistical support - please contact Dr. Ingo Blechschmidt, Head of the Grimsel Test Site, for further details.
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