Text and set of six plates of basic subsidence-related problems; practical approaches to land development; extent of mining. The plates include: 1) extent of mining, 2) depth of cover, 3) mine pillars, 4) probable thickness of extracted coal, 5) subsidence inventory, 6) subsidence hazards. 92 pages. 6 plates. 32 figures. Digital PDF download. EG-09D
The problem of subsidence resulting from the undermining of the surface has received a great deal of study over the past 100 years. Much of this work has been done in Europe where industry, population density, and coal mining tended to grow and develop in the same areas. Damage to surface structures in highly urbanized areas such as the Ruhr and the English Midlands led to intensive investigations as to how to predict where and when subsidence would occur and how to prevent or minimize such subsidence. Until recently most of the significant research on surface subsidence was done abroad and has been published in journals which are not easily obtainable or are in a language other than English.
In Europe, most underground coal mining is done by methods different than those commonly used in the Boulder-Weld coalfield. For this reason, one must be cautious in applying European principles of subsidence prediction to the Boulder-Weld coalfield where the layout and condition of the mines are quite different.
In the last decade, land development has encroached on the undermined area of the Boulder-Weld coalfield, and the importance of subsidence has been recognized. This study is directed primarily toward the problems of land-use in those undermined areas where subsidence has occurred in the past and may occur in the future. Absolute predictability of the amount and area of subsidence in the Boulder-Weld coalfield is not possible with records now available.
In Europe land-use plans have evolved to take subsidence into account, and detailed records have been maintained over long periods of time. It is unfortunate that the level of record-keeping in the Boulder-Weld coalfield has not been geared to land-use needs, because the present lack of data severely limits the accuracy of subsidence prediction. Within the limitations imposed by the adequacy of mine data, this study is intended to bring together a body of information that will be useful to planners and geologists involved in bringing the land to its optimum use.