外文翻译-长壁开采引起的断层活化和地面延迟沉降在英国煤田中的研究.doc

1、第19页翻 译 部 分英文原文LONGWALL MINING-INDUCED FAULT REACTIVATION AND DELAYED SUBSIDENCE GROUND MOVEMENT IN BRITISH COALFIELDSAbstract: Faults located in areas undergoing mining subsidence during the longwall extraction of coal seams may undergo reactivation. This has been observed and documented throughout

2、 the UK (and in other major coalfields around the world) over the past 150 years. The impact of subsidence induced fault reactivation may cause moderate to severe damage to foundations, houses, buildings, structures and underground services, as well as damage to agricultural land through disruption

3、of drainage and alteration of the gradient. Monitoring of faults, as they are affected by undermining, has resulted in a better understanding of fault reactivation mechanisms and of the various styles of fault reactivation, in different geological and mining settings.The duration of fault reaction i

4、s difficult to determine due to the lack of observational data. However, trough subsidence following longwall extraction of coal is rapid, often being completed within weeks to months. This is commonly followed, shortly afterwards, by a period of delayed subsidence known as residual subsidence, whic

5、h in the British Coal Measures, rarely accounts for more than 10%of the total subsidence. In many circumstances, where faults are not present, residual subsidence is complete within four months, although several cases have been recorded where subsidence effects were still being observed more than tw

6、o years after mining had finished. Generally, it is accepted that fault reactivation sometimes may extend over the period of residual subsidence.In parts of the abandoned or partially active coalfields in the UK, relatively smaller ground movements have been observed in the vicinity of fault outcrop

7、s many years after mining has ceased. The reasons for this are not fully understood. Nonetheless, prolonged periods of fault reactivation may have an important effect on land use and construction.The objectives of this paper are to consider fault reactivation and, in particular, to document examples

8、 of post-mining ground movements around fault outcrops and to discuss possible causal mechanisms. Features associated with these movements include increases in elevation of the ground surface and deformation (e.g. subsidence, scarps, compression and tension)of the ground surface in the vicinity faul

9、ts. These features, in turn, may be associated with groundwater or mine water rebound.IntroductionFaults located in areas where longwall mining subsidence is taking place may be susceptible to reactivation. This may result in the generation of scarps at the ground surface. Fault scarps in the coalfi

10、elds of the UK vary from subtle topographic deflections and flexures only recognizable across agricultural land or roadside verges, to distinct, high-angled fault scarp walls 3-4 m high and at least 4 km long. They occur in rural and urban parts of Britain in both the exposed and concealed coalfield

11、s. The consequences of fault reactivation may be damage to surface structures, services, utilities and transport networks. Frequently, reactivated faults also have disrupted agricultural land through alteration of drainage and gradient. In addition, fault reactivation may cause the failure of natura

12、l slopes, high-walls in opencast mines, engineered cuttings and embankments, and can influence stream and groundwater flows.Fault reactivation that is contemporaneous with mining subsidence occurs because of the release of strain accumulations along the fault zone. This can cause shear displacements

13、, resulting in uneven subsidence on one side of the fault relative to the other. Unfortunately, the duration of fault reactivation associated ground movements is difficult to assess because of the lack of reliable observational data. Public safety often is of direct concern when incremental ground-s

14、urface displacements occur rapidly, as when blocks of ground move into open-spaces of underground workings.Overview of mining subsidenceThe majority of the coal mined in Britain in the twentieth century and at present, although now greatly reduced in amount, was and is by longwall mining. Longwall m

15、ining involves the total extraction of a series of panels of coal that are separated by pillars whose width is small compared to overburden thickness. The coal is exposed at a face 30 to 300 m in width between two parallel roadways. The roof is artificially supported temporarily at the working face

16、and in, and near, the roadways. After the coal has been won and loaded the artificial face supports are advanced, leaving unsupported rock, in the areas where coal has been removed, to collapse. Subsidence at the surface more or less follows the advance of the working face and may be regarded as immediate and contemporaneous with mining, producing more or less direct effects at the surface. The subsidence that occurs over a completely mined out area