外文翻译-深埋煤层顶板分区破裂化的原位探测.doc

1、 翻 译 部 分 第31页英文原文In situ explorations on zonal disintegration of roof strata in deep coalminesY.L. Tan*, J.G. Ning, H.T. LiState Key Laboratory of Mine Disaster Prevention and Control of China, Shandong University of Science and Technology, Qingdao, Shandong 266590, China1 IntroductionZonal disinteg

2、ration is a special phenomenon that occurs in the deep rock masses. It was for the rst time dened and explained by Shemyakin et al. 15 as “alternated regions of fractured and relatively intact rock masses appearing around or in front of the working stope during the excavation of tunnels in the deep

3、rock mass, which had never been observed in the shallow rock engineering before.The zonal disintegration phenomenon provides us with a new idea for understanding deep rock failure mechanism and behaviors. In order to explore the mechanism and distribution of zonal disintegration, progresses on analy

4、tical model and numerical simulation 611, in-situ observations 1214, and laboratory tests 15,16 were made in the past few years. It was found that zonal disintegration phenomena are directly related to rock mass properties and high conned stress.Zonal disintegration occurs not only in deep metal min

5、es and underground engineering, but also in deep coalmines 14. Compared with other rock engineering, coal-mining activity is a typical dynamic one as a coalface advances. In deep coalmines, rock failure is strongly inuenced by the continuous longwall extractions. For instance, in the longwall mining

6、 method, roof strata behind the longwall face are abandoned and allowed to cave-in. Thus, special attention should be paid to the fact that the stress distribution in the rock strata varies with the coalface advances; high pressure zones are formed in the adjacent coal due to the transfer of stresse

7、s 17. Dynamic stress not only induces roof fracturing rapidly in roadways 18, but also easily brings about the failure extension of overburden and underlying rock mass in a large region 19. In a sense, the formation of zonal disintegration in a deep coalmine is much more complicated than that in the

8、 other underground engineering.Some achievements in zonal disintegration have been made as mentioned above. However, it is not quite enough, because China is the largest coal mining country in the world, and more and more coalmines are becoming deep ones. Severe disasters as rock burst, insufcient s

9、upport in roadways, etc., induced by deep rock failure are increasing more and more. It is still far from understanding the rock failure mechanism in deep coalmines. Thus, the study of the formation of zonal disintegration in deep coalmines is signicant for China.Bearing this in mind, we used a bore

10、hole camera technology to explore the zonal disintegration developing process in roof strata inuenced by multiple mining activities. The sites for the eld probes are located in the Suncun Mine, the Liangzhuang Mine, and the Erzhuang Mine, China. This note begins with a brief discussion on disintegra

11、tion mechanism of deep coal measure strata. We then describe a borehole camera technique to explore the fracture distribution along the wall of a hole in deep roadways, and present the observed zonal disintegration outline. The observation results are used to try to identify the inuences on zonal di

12、sintegration distribution, mainly including weak layers or beddings, as well as different mining activities.2 Mechanism of zonal disintegrationIn coalmines, coal measure strata are composed of sedimentary rocks, which are different from metamorphic rocks and igneous rocks. The heterogeneous sediment

13、ation caused a lot of cracks with different sizes and different occurrences in sedimentary rocks. So the mechanical properties and failure patterns of sedimentary rocks are much more complex, especially in deep working regions. Generally, in a shallow working region, the surrounding rock mass of a h

14、orizontal tunnel may be classied into three zones: a residual plastic zone, a softened plastic zone, and an elastic zone, accordingly 16. But in a deep working region, in the surrounding rock mass of a horizontal tunnel appears several alternate fractured regions and relatively intact zone. The occu

15、rrence of such a zonal periodic structure cannot be adequately interpreted with classical continuum models based on traditional rock mechanics. Some key inuences on disintegration such as microcracks and macrocracks, creep behavior, high in-situ stresses, compressive strength of rock, and stress red

16、istribution along interface of strata should be considered systematically.Some weak structure zones containing a lot of microcracks and macrocracks in sedimentary rocks are the origin forming disintegration in coal measure strata. In a deep working region, the stress is high naturally. Once a tunnel is excavated, the stress in surrounding rock mass redistributes, the tangential stress increases