精选优质文档-倾情为你奉上Control and prevention of gas outburstsMara B. Daz Aguado C. Gonzlez （International Journal of Coal Geology 69(2007)253-266）Abstract： Underground coal mines have always had to control the presence of different gases in the mining environment. Among these gases, methane is the most important one, since it is inherent to coal. Despite of the technical developments in recent decades, methane hazards have not yet been fully avoided. This is partly due to the increasing depths of modern mines, where methane emissions are higher, and also to other mining related circumstances, such as the increase in production rates and its consequences: difficulties in controlling the increasing methane levels, increasing mechanization, the use of explosives and not paying close attention to methane control systems. The main purposes of this paper are to establish site measurements using some critical parameters that are not part of the standard mining control methods for risk assessment and to analyze the gas behavior of subvertical coal seams in deep mines in order to prevent gas incidents from occurring. The ultimate goal is the improvement in mining conditions and therefore in safety conditions.Key words： Coal mines，coal-seam methane，gas pressure，permeability，gas outburst- potential. 专心-专注-专业一.Introduction Coalbed and coal mine methane research is thriving due to the fact that power generation from coal mine methane will continue to be a growing industry over the coming years in certain countries. For instance, China, where 790 Mm3 of CH4 were drained off in 1999 (Huang, 2000), has 30 Tm3 of estimated CBM potential in the developed mining areas (Zhu, 2000). The estimate by Tyler et al. (1992) of the inplace gas in the United States is about 19 Tm3, while Germanys total estimated coalbed methane resources are 3 Tm3, very similar to Polish or English resources (World Coal Institute, 1998). This increase in the CBM commerce has opened up new lines of research and has allowed the scientific community to increase its knowledge of some of the propertiesof coal and of methane gas, above all with respect to the properties that determine gas flow, which until now had not been sufficiently analyzed. Some of these parameters are the same ones that affect the occurrence of coal mining hazards, as methane has the potential to become a source of different fatal or nonfatal disastrous events. 二.Description of the Asturian Central basin and of the 8thCoalbed The 8th Coalbed of the RiosaOlloniego unit, located in the Southwest of the Asturian Central Coal Basin (the largest coal basin in the Cantabrian Mountains, IGME, 1985), has CBM potential of about 4.81 Gm3. This is around 19.8% of the estimated resources of the Asturian Central Basin and 12.8 % of the total assessed CBM resources in Spain (Zapatero et al., 2004). 3.84 Gm3 of the CBM potential of the 8th Coal-bed belongs to San Nicols and Montsacro: 1.08 Gm3 to San Nicols area and 2.76Gm3 to Riosa, down to the 800m level (IGME, 2002). The minable coalbeds of this unit are concentrated in Westphalian continental sediments (Surez-Ruiz and Jimnez, 2004). The RiosaOlloniego geological unit consists of three seams series: Esperanza, with a total thickness of 350 m, contains 36 coalbeds with a cumulative coal thickness of 3.5 to 6.5 m; Pudingas, which is 700 m thick, has 35 coalbeds with a thickness of 57m; whereas the Canales series, the most important one, I 800 m thick, with 812 coalbeds that sum up to 1215 m thick. This series, which contains the 8th Coalbed, the coal-bed of interest in this study, has a total thickness of 10.26mat SanNicols and 15.13matMontsacro (Pends et al., 2004). Fig. 1 shows the geological map of the two coal mines, whereas Fig. 2represents a front view of both mines and the location of the instrumented areas. In this particular study, the 8th Coalbed is situated at a depth of between 993 and 1017 m, in an area of low seismi intensity. Instantaneous outbursts pose a hazard to safe, productive extraction of coal in both mines. The mechanisms of gas outbursts are still unresolved but include the effect of stress, gas content and properties of the coal. Other factors such as geological features, mining methods, bord and pillar workings or increase in rate of advance may combine to exacerbate the problem (Beamish and Crosdale, 1998). Some of the main properties of the 8th Coalbed favoring gas outbursts (Creedy and Garner, 2001; Daz Aguado, 2004) had been previously studied by the mining company, in their internal reports M.B. Daz Aguado, C. Gonzlez Nicieza / International Journal of Coal Geology 69(2007)253 Fig. 1. Geological map.As well as in the different research studies cited in Section The geological structure of the basin, the stress state of the coal-bed and its surrounding wall rock and some properties of both coal-bearing strata and the coalbed itself. The next parag