1、英文原文英文原文 Mining subsidence- past, present, future Introduction Minings 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 en
2、ough to 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 speculate
3、s on advances in the 21st century. Keywords: Subsidence,coal mining,history of mining. Extent of problem - 1990 When 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 c
4、ombined. For 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
5、subsidence 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 i
6、n excess of $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 experience and theories prior to 1890 Early 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 (
