1、英文原文Mining subsidence- past, present, futureIntroductionMinings origins are ancient and unknown. The earliest mines probably consisted of workings to recover chert for stone tools, or pigment and gems for ornamentation. As these workings extended underground, eventually a void became large enough to
2、 cause the first mine subsidence. Although this event was not documented, mine subsidence has been a problem for many years. This paper briefly reviews the extent of mine subsidence in 1990, ideas prior to 1890, the status in 1890, and significant advances between 1890 and 1990, and speculates on ad
3、vances in the 21st century.Keywords: Subsidence,coal mining,history of mining.Extent of problem - 1990When we think of underground mining we often think of metal ores, coals, salts, and aggregates. However, coal mining impacts a vastly larger amount of land than all other types of mining combined. F
4、or example, in the United States coal is found in 37 states and mined underground in 22 states (HRB-Singer, Inc., 1980). Underground coal mining is estimated to eventually cover 40 million acres with 8 million already undermined (HRB-Singer, Inc.1977). Johnson and Miller(1979) report that subsidence
5、 due to mining had affected more than 2 million acres in 30 states. Coal mining caused over 99% of the subsidence, since all other metal and non-metal mines affected only 17 000 acres (Johnson and Miller, 1979).Underground coal mining is estimated to cause surface subsidence damage costs in excess o
6、f $1 billion from 1973 to the year 2000, with $30 million of damage to structures annually (US Government Accounting Office, 1979).With the preponderance of subsidence being due to coal mining, it is understandable that most subsidence research and theories are related to coal mining. Subsidence exp
7、erience and theories prior to 1890Early in the 15th century court records from the County of Durham in England indicate a jury awarded 200 for repair of a house damaged by coal mining (Young and Stock, 1916).In heshire, England, shafts were sunk shortly after 1670 to mine a shallow salt bed. Serious
8、 surface breaks occurred in 1750 (Young and Stoek, 1916). Belgian engineers were among the first to make a scientific study of subsidence due to mining. In 1825 a commission investigating the cause of surface cracks in the city of Liege concluded that an interval of 300 feet between the mine working
9、s and the ground surface wasmore than sufficient to prevent subsidence (Young and Stoek, 1916). J. Gonot, a Belgian engineer, is usually given credit for formulating the first theory of subsidence during a study at Liege in 1839. However, he did not publish it until 1858 and a similar idea was prese
10、nted by a French Engineer, Toillez, in 1838. Gonot claimed that following extraction of coal the overlying strata would sink and the angle of fracture would be perpendicular to the plane of the coal bed. He also indicated that the break extends through to the surface, irrespective of the depth of mi
11、ning (Young and Stoek, 1916). As early as 1859 there were regulations in Austria controlling the mining of coal under railways (Young and Stoek, 1916). In 1867, A. Schulz, a German engineer, published his ideas on the angle of fracture and the size of pillars necessary to protect the ground surface
12、(Young and Stoek, 1916). The Prussian government appointed a commission in 1868 to collect information from other countries on the influence that mine workings may have on surface buildings. They found that the majority of Belgian engineers believed that when the coal is entirely removed, the most c
13、areful packing gives no guarantee against damage to surface buildings, that the packing only lessens the sinking; and that the surface may be protected by leaving pillars equivalent to half the area of the coal seam. In England the commission found the following opinions:The working of coal at every
14、 known depth may affect the surface, but at depths greater than 400 metres (1300 feet) it can cause damage only to certain buildings.In the case of complete extraction, filling may be a means of effective protection.Leaving pillars constitutes an efficient protection (Young and Stoek, 1916).In anoth
15、er study of subsidence at Liege, not surprising in light of the first commissions finding that mining below 300 feet would not damage the surface, G. Dumont in 1871 recognized that drainage of old workings or the flooding of a mine may reinitiate subsidence many years after the initial movements (Yo
16、ung and Stoek, 1916).In 1884 Jicinsky summarized Austrian experience and postulated the harmless depth concept. With caving of the rock strata overlying the mine workings the rock fractures and increases in volume. For mine voids that are small relative to the mine depth, the likelihood of subsidence decreases wth increasing depth of mining. However, extending this concept to areas of nearly complete extraction with dimensions significantly larger than the de
