Water-Rock Interaction Mechanisms and Ageing Processes in Chalk - Advances in Data, Methods, Models and Their Applications in Geoscience - page 165

- a convergence meter between the wall and the roof of the mine
- three pore-pressure sensors together with rock temperature sensors, fixed at different
points within the pillar (15 cm, 35 cm, and 70 cm from the surface)
- an extension meter measuring lateral displacement from the pillar surface at two points
within the pillar
Data were recorded from February 2004 to February 2008, and the following were observed:
-

ambient hygrometry was varying between 85% and 100%

- there was (very slight) seasonal variation in the water level in the galleries, with an

overall decreasing trend (Fig. 2)

- seasonal variation in pore pressure and rock temperature within the instrumented pillar

was occurring (Figs. 3 and 4), indicating cycles of alternating saturation/desaturation

- pore pressure and rock temperature were generally decreasing from the surface to the

core of the pillar (Figs. 3 and 4 respectively)

- during each rise in water level there was increasing pore pressure within the pillar (Fig.

3) and lateral extension (swelling) of the pillar (Fig. 5)

- convergence of the wall and roof over time (Fig. 6)

Fig. 1. Diagram of the full instrumentation employed in the Estreux mine