Designing Reinforced Rock

by John A. Bischoff, (M.ASCE), Sr. Managing Principal and V.P.; Woodward Clyde Consultants, Oakland, CA,
Stephen J. Klein, (M.ASCE), Sr. Project Engr.; Woodward Clyde Consultants, Oakland, CA,
Thomas A. Lang, (F.ASCE), Sr. Consultant; Woodward Clyde Consultants, Oakland, CA,

Serial Information: Civil Engineering—ASCE, 1992, Vol. 62, Issue 1, Pg. 64-67

Document Type: Feature article


The reinforced rock arch design method has been used to stabilize coal mine excavations for 40 years, but so far has been applied to only a few tunnels. The use of rock reinforcement develops a stable reinforced rock arch that can permanently and safely span an underground tunnel excavation. The design method provides for a rational structural analysis of the reinforced rock arch and its specific reinforcement requirements. The arch acts like a segmented masonry voussoir arch. It has no bending capacity or tensile strength but transmits the loading by compression from the tunnel crown to the abutments. Cost savings are estimated at 10-20%, depending on geologic conditions. The article describes three U.S. projects using the method: the Hanging Lake Tunnel on the Glenwood Canyon I-70 project in Colorado; the Reverse Curve Tunnel, also in Glenwood Canyon; and the widened Keystone Tunnel project, near Mount Rushmore in South Dakota.

Subject Headings: Tunnels | Arches | Tensile strength | Project management | Rocks | Coal mining | Excavation | Load bearing capacity | United States | Colorado | South Dakota

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