DOI: 10.1615/ICHMT.1986.IntSympHMTinRefCryo
ISBN Print: 978-3-54017-957-3
A Cryogenic Device to Study Geotechnical Problems at Low Temperatures
Краткое описание
In order to conduct measurements at very low temperaturee for geotechnical purpose, an isothermic chamber has been conceived by M. SAKLY and adapted by P. DE SLOOVERE to undergo geotechnical experiments, The results are used by P. COLIN for underground storage projects at very low temperatures. The LNG storage at atmospheric pressure in underground cavities only requiree small excavation and is safe. The main question ie how the soil will stand this temperature fall, in fact, in major cases, the free water freezes at 0°C but when it is present within the inert substances, its freezing point is somewhat below 0°C. The phase change is always accompanied by the variation of physical properties such as density and involves strain and stress variation in rocks. The thermodynamical study was published by [1].
The thermal behaviour of a cavity and surrounding rocks cooled down to − 196°C was studied by [2] and the details of the measurements conducted in and around the same cavity, were developed by [3].
The aim of this paper is to estimate the efficiency of the chamber and to describe the principle of methods used to evaluate the dilatancy effect and velocity propagation within the rocks. The first results are shown but the discussion about the behaviour of rock samples is not enclosed in this paper and more information will be published later.
At Schelle (Belgium), a pilot cryogenic storage was cooled down to − 196°C in 1981−1982 [2]. An important thermal geotechnical and geophysical survey was set up inside and around the cavity [4]. It appears that two fundamental factors are necessary to define the cavity behaviour under low temperatures i they are the strain of the rock versus temperature and the seismic velocity of the rock. Therefore, a device was developed in order to conduct these two tests in the range of temperature + 20°C to − 160°C.