外文翻译-覆岩采动水平裂隙的定位：现场监测与预计.doc

1、 第30页翻译部分英文原文Localization of mining-induced horizontal fractures along rock layer interfaces in overburden: field measurements and predictionDepartment of Geological and Environmental Sciences,BenGurion University of the Negev,V. PalchikAbstract：The locations of mining induced horizontal fractures a

2、long rock interfaces in the overburden of Donetsk Coal Basin were identified using an original experimental device. The device traps methane from horizontal fracture zone (100fold coal seam thickness) over an active longwall mining excavation. Presence or absence of horizontal fractures along rock l

3、ayer interfaces is correlated with physical characteristics of the overburden, such as thickness, uniaxial compressive strength of overburden rock layers, location of rock layer interfaces and thickness of extracted coal seams. As a result, a combined criterion based on these physical characteristic

4、s is proposed to predict the presence of overburden horizontal fracturing in coal mine operations.Keywords：Rock layer interface; Horizontal fracture; Longwall coal mining; Natural gas emission;1 IntroductionIt is known (Karmis et al. 1983; Hasenfus et al. 1988; Whittaker and Reddish 1989; Kendorski

5、1993; Chekan and Listak 1993; Palchik 2003) that there are three distinct zones (caved zone, fractured zone and continuous deformation zone) of movement in the overburden strata appearing in response to longwall mining (see Fig. 1a; Palchik 2003). In the caved zone located immediately above undergro

6、und workings, rock layers fall to the mine floor and are broken into irregular shapes of various sizes (Kratzsch 1983; Palchik 2002a). Above the caved zone is the fractured zone, which can be divided into three parts: rock blocks, through-going vertical fractures and horizontal fractures caused by b

7、edding layer separation. In the lower part of the fractured zone (Fig. 1b), rock layers are broken into blocks by throughgoing vertical fractures and horizontal fractures due to bed separation. In the middle part of the fractured zone (Fig. 1c), there are also horizontal fractures due to bed separat

8、ion, whereas the number of through-going verti- cal fractures is less than in the lower part of the fractured zone. In the upper part of the fractured zone (Fig. 1d), the formation of vertical fractures through the thickness of rock layers does not occur, and there are only separate horizontal fract

9、ures along weak-strong rock layer interfaces. The thickness of the fractured zone varies greatly amounting to 20 to 100-fold seam thickness (Turchaninov et al. 1977; Peng 1992; Palchik 2003). The zone above the fractured zone is a continuous defor- mation zone without any major fractures.Horizontal

10、fractures along weakstrong rock layer interfaces play an important role in the movement of an overburden, since they are natural planes of weakness in which separation occurs at overburden lamination. The formation process, thickness and location of horizontal fractures may influence the value and d

11、uration of rock mass and ground surface subsidence. Moreover, these fractures are sources of methane and concentrators of maximum tensile deformations, which may be danger- ous for mining constructions.Palchik (2003) has shown that the extent of fractured zone induced by mining can be determined bas

12、ing the change in natural methane emission from this zone. Mathematical models (Palchik 2002b) were proposed to describe the process of methane emission from fractured zone in time. Field measurements (Palchik 2003) of the extent of fractured zone were performed using the method of tampion. The tamp

13、ion is moved along a vertical gas well and can block the latter above and below the fractured zone in order to measure gas emission from this zone. As a result, the following extents of the fractured zone were defined: Height of the zone of interconnected fractures (combined thickness of the caved z

14、one and the lower and middle parts of the fractured zone (see Fig. 1a), where horizontal and vertical through-going fractures are interconnected and form a system of through channels. Location of separate horizontal fractures in the upper part (Fig. 1d) of fractured zone.Fig. 1 Scheme of movement in

15、 overburden strata: a all zones movement (after Palchik 2003); b lower part (rock blocks of fractured zone; c middle part (throughgoing vertical fractures) of fractured zone; (d) upper part (separate horizontal fractures) of fractured zoneHowever, localization of horizontal fractures in lower (Fig.

16、1b) and middle (Fig. 1c) parts of fractured zone was not performed, since at use of the method of tampion, gas gets into gas meter from several outlets of system of through channels in zone of interconnected fractures.This paper presents a new approach to the localization of horizontal fractures along rock layer interfaces in all three parts of the fractured zone. In this study, methane is trapped from each of horizonta