Barkley Lock, completed in 1961, is the first major construction feature of the multipurpose Barkley Reservoir Project located on the lower Cumberland River.
Barkley Lock is founded on rather massive Mississippian limestone that contains two principal systems of essentially vertical joints. Enlargement of these joints by solution is the source of nearly all the bedrock-foundation problems at Barkley Project. Solution channels 2-3 feet wide and 20 - 30 feet deep are common. Such openings are at least partially filled with clay, particularly near the bedrock surface, but numerous voids carry circulating water under pressures correlative with the river.
A very deep solution-channel zone was discovered early in the foundation explorations. It crossed the river diagonally and passed under the lower gate of the lock, as initially located. To minimize the foundation problems, the lock and dam were shifted upstream so that the solution zone occurred beneath the lower guide wall, which is not a hydraulic structure. Ihe guide wall over the deep solution zone was placed on a 165-foot long reinforced-concrete slab which bridges the clay-filled openings.
To prevent piping under the lock cofferdam, its perimeter was grouted, using cement and cement-sand grout pumped into holes drilled at a 45-degree angle parallel to the alignment of the cofferdam. More than 50,000 cubic feet of grout was pumped into rock openings under the edge of the cofferdam. This consolidation doubtlessly contributed to the exceptionally dry conditions encountered in the lock excavation.
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Prepared for the Division on Engineering Geology of the Geological Society of America, Engineering Case Histories 4 includes 7 case histories examining land subsidence, foundation treatment, tunnel engineering, grouting alluvial fill, landslides, and more.