Mine Subsidence and Support Methods in Pittsburgh Area

by Richard E. Gray, (M.ASCE), Vice Pres.; General Analytics, Inc., Monroeville, PA,
James F. Meyers, (A.M.ASCE), Proj. Engr.; General Analytics, Inc., Monroeville, PA,

Serial Information: Journal of the Soil Mechanics and Foundations Division, 1970, Vol. 96, Issue 4, Pg. 1267-1287

Document Type: Journal Paper


The Pittsburgh area exhibits two distinct subsidence problems: (1) Active mining at depths of 300 ft or more beneath the surface; and (2) subsidence associated with structures located over old mine workings at relatively shallow depths. In areas of active mining, subsidence damage is prevented by leaving coal pillars in place to support the ground surface. For structures located over old mines with shallow cover, the method of support selected is dictated by the cost and the degree of risk the owner is willing to accept. Each site presents a unique problem and extensive investigation is required. The investigation involves the study of existing mine maps, borings drilled to the mine level, borehole photography and where possible, opening and inspecting the mine. Methods of support include grouting, construction of concrete piers within the mine, drilled piers and subsurface stabilization utilizing grout column construction. Examples of subsidence damage and support methods are presented as case histories.

Subject Headings: Land subsidence | Mines and mining | Site investigation | Boring | Grouting | Concrete construction | Piers | Case studies | Pittsburgh | Pennsylvania | United States

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