Study and Analysis of Surface Subsidence Over the Mined Pittsburgh Coalbed.

摘要

The purpose of this study is to investigate cases of subsidence over abandoned mined-out areas of the Pittsburgh coal identified from published and unpublished sources and to determine through a consideration of the geology,topography,climate,mining activity,and evidence at ground surface,what mechanisms control subsidence and under what circumstances it takes place. The study was performed in two phases,the first to identify all documented incidents of subsidence in mined-out areas of the Pittsburgh coal region;and the second,to study a particular portion of the region in detail,collecting pertinent data relative to the sites within,characterizing the nature of the subsidence and its economic consequences,and determining the applicability of the findings to other areas where similar problems with the collapse of abandoned mines have been encountered. The report identifies 354incidents of subsidence in the 8,000-square-mile Pittsburgh coal region. One is located in Maryland,one is located in West Virginia,and the remainder are located in Pennsylvania. All were confined to the period 1955-76,an interval that was dictated by the availability of information. Data and locations of sites of subsidence are presented on graphs and tables and on U.S. Geological Survey 7.5-minute quadrangle topographic maps. Case histories of several incidents of subsidence above abandoned mines are presented and subsidence in southwestern Pennsylvania is discussed in detail.