1、 附录A 原文The location of abandoned mine workingsusing thermal techniquesLaurance J. Donnelly，David M. McCannAbstractBetween 1926 and 1956, laboratory experiments and underground observations demonstrated the relationship between barometric pressure decrease and the efflux gas in mines. This resulted i
2、n the establishment of early warning systems in some British mines when significant falls of atmospheric pressure were expected. In 1993, frost circles were observed on the ground surface, above abandoned mine shafts. These were caused by warmer mine air escaping into the atmosphere, via the mine sh
3、afts. The temperature of the ground above, and in the vicinity of, abandoned mines was subsequently monitored using digital thermometers, a precision radiation thermometer and infrared thermalphotography. This was followed by the use of a longer-term, ground temperature monitoring technique, using d
4、igital temperature recorders, which monitored the ground temperature every 2.5 minutes for a period of 14 days. The ground temperatures above the abandoned mine shafts were also found to be related to fluctuations in barometric pressure, agreeing with the earlier observations. During periods of high
5、 barometric pressure mine gases were prevented from escaping into the atmosphere and accumulated in the mine voids. Following a drop in barometric pressure the mine gases were capable of escaping into the atmosphere, where they underwent oxidation. This produced an increase in ground temperature in
6、the order of a few degrees centigrade. The temperature differential may be sufficient to be detected by remote thermal imaging techniques, provided that they are undertaken in suitable climatic conditions.This type of remote, reconnaissance technique, is particularly applicable to the British Isles
7、due to the abundance of abandoned mines workings and the regular fluctuations in climatic conditions. 2000 Elsevier Science B.V. All rights reserved.Keywords: Coal; Geohazard; Minegas; Mining; Shafts; Thermal techniques1 IntroductionDuring underground coal mining operations, ventilation is essential
8、 to prevent gas accumulation; this is controlled by fans, screens, air locks anddoors. Investigations and experiments have concluded that the reservoir of gas that exists in certain rock formations can expand and contract with changes in atmospheric pressure. The idea that the efflux of methane gas
9、in mines was associ-ated with changes in barometric pressure has long been known (Fig. 1)Experiments have been undertaken to forecast the emissions of methane with barometric pressure changes。These were carried out with some success and have been compared with actual observations (Fig. 2).Observatio
10、ns carriedout over a 5 day period on a long-wall face clearly demonstrate the relationship between barometric pressure decrease and increase in methane at the edge of the goaf (Fig. 3).Owing to gas emissions caused by a reduction in atmospheric pressure, early warning systems were established in som
11、e British mines. Forinstance, in December 1949, the Central Forecasting Office of the Meterological Office issued special reports when sharp falls of pressure were expected. These sharp falls were defined as one of 48 mb, in 3 h, Durst (1956). A very sharp fall was considered as one occurring when t
12、he pressure fell by 8 mb in 3 h. In one period, from March 1951 to April 1952 warnings were issued on 36 occasions and 50% of these were successful. This indicated the difficulty of accurate and precise forecasting.During the winter of 1993, an airborne survey was being undertaken at the former Wet
13、Earth Colliery site in the Lancashire Coalfield to observe mining-induced fault reactivation (Donnelly, 1994). This is a green-field site adjacent to theRiver Irwell, in a region of urban occupation. At the time of this survey a ground frost prevailed at the site. From the air, circular features wer
14、e observed on the ground although there were novisible mine shafts.These circular features, or frost circles, corres-ponded to the approximate position of a mine shaft marked on a mine plan; it was suspected that the other features may also represent the site of abandoned mine shafts. A ground inspe
15、ction immediately followed the airborne observations, but the circular features were not visible. It was hypothesised that the air in the mine shafts was slightly warmer than the surrounding rock mass and produced a sufficient temperature difference to change the crystallinity of the ground frost, b
16、ut insufficient to melt it completely.This paper documents the monitoring of ground temperatures above abandoned mine shafts during different barometric pressure conditions. This resulted in the provision of information on optimum conditions for the remote thermal detection of mine shafts.2 Hazards presented by abandoned mine shaftsAbandoned mine shafts in the vicinity of a property or structure represent a potential haza
