1、翻译部分英文原文SOME OF OUR EFFORTS ON THE IMPROVEMENT OF MINING SAFETY AND THE RELIABILITIES OF MINING MACHINERIESAbstract: To improve the safety of coal mine and the reliabilities of mining machineries is the main aspect of present scientific research. This paper introduces some of efforts and achievement
2、s in this field. They are: (1) The selective earth leakage protection of 6 KV underground power supply system with insulated neutral ; (2) The detection of mine methane and power supply tripping device ; (3) The protection against the hazard of underground static electric charge ; (4) The research o
3、f reliability of the shearer motor ; (5) The test and improvements of the reliabilities of mining machineries.INTRODUCTION In the last 50 or 60 years the coal mining industries all over the world made great advances in mechanization and safety. Our country had also large improvements in these fields
4、, but large amounts of works have to be done. Recently the problem of reliabilities of mining machineries drew much attentions of many countries and was considered as the main direction of mining research . For more than a decade , in the same time of improving the degree of mechanization of our coa
5、l mines, we worked also on mine safety and reliabilities of mining machineries and got some achievements. Let me make some simple introduction on them.Numerical modelling of the effects of weak immediate roof lithology on coal mineroadway stabilityAbstract: The stability and associated design of roo
6、f reinforcement requirements of tunnels driven in United Kingdom. Coal Measures strata is directly related to the engineering characteristics of the immediate roof lithology and the effects of redistribution of the in-situ stress. Numerical modelling carried out by the authors has been used to simul
7、ate the widely observed detrimental effects of both high horizontal stress and weak immediate roof lithology on tunnel roof stability. Different numerical modelling techniques, such as continuum, discontinuum and hybrid finite element-discrete element codes, have been used tomodel the deformational
8、behaviourof Coal Measures strata and are discussed in the context of specific case examples to highlight their application and suitability formodelling of weak rock. The modelled results demonstrate that the thickness of the relatively weak mudstone in the roof of the tunnel has a significant influe
9、nce on the extent of failure and, ultimately, the need for additional reinforcement.1. IntroductionUntil recently 5 mines worked the Barnsley seam in the Selby Complex (Wistow, Stillingfleet, Riccall, Whitemoor and North Selby). The seam dips at approximately 7 to the North-East, ranging in depth fr
10、om 250 mWest of the Wistow Mine to in excess of 1200 m East of the North Selby Mine. Typical seam thickness varies from 3.5 m in the West to 1.8 m in the East of the Selby Coalfield. The roof strata typically consist of an immediate, relatively weak mudstone (up to 1 m thick) overlain by more compet
11、ent silty mudstones, siltstones and sandstones. The mudstone thickness varies across the Coalfield, ranging from non-existent due to high energy depositional river channels where the sandstone lies directly above the seam to an extensive thickness of greater than 4 m. Typical tunnel or roadway dimen
12、sions are 3.5 m high by 5.0 m wide.The successful implementation and subsequent use of roofbolting in United Kingdom coal mine tunnels have provided a large database of tunnel deformation monitoring information, including in-situ measurement of strata behaviour, tunnel deformation and reinforcement
13、performance. Kent et al. (1999) provided a summary of the analysis and interpretation of deformation monitoring data from across the Selby Complex during the period 1988 to 1994. The database provided an ideal opportunity to investigate how geological and stress variations affect the stability and d
14、eformational behaviour of tunnels driven through Coal Measures strata. The data were established for tunnels on drivage, prior to face retreat and any additional deformation associated with longwall extraction. Detailed analysis of the database confirmed that the stability and associated design of r
15、oof reinforcement requirements of tunnels driven in United Kingdom Coal Measures strata is directly related to the lithology of the immediate roof of the excavation and the redistribution of the in-situ stress caused by creation of the excavation (Hurt (1992), Kent (1996), Kent et al. (1999) and Sid
16、dall and Gale (1992). For example, significant increase in tunnel roof deformation is observed when excavations are driven perpendicular to the maximum horizontal principal stress direction. Tunnels driven at an angle to the in-situ stress field suffer asymmetrical deformation, with pronounced observed stress effects that require additional reinforcement for stability. These observed effects include the formation of “guttering” or
