SEDL / STP / STP1089-EB / STP25065S

Deep Chemical Injection for Protection of an Old Tunnel

Munfakh, GA
vice president and head of the Geotechnical Department, Parsons Brinckerhoff Quade & Douglas, Inc., New York, NY

Pages: 13    Published: Jan 1991

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Abstract

The foundation of a 19th Century brick-lined railroad tunnel was reinforced by a deep chemical stabilization scheme which allowed successful construction of two new tunnels about 7 ft. (2 m) below its invert. After evaluation of several protection schemes which included ground freezing, reinforcement with micro piles and conventional structural underpinning, chemical grouting of the foundation soils was selected based on technical and economical merits. Laboratory and field grouting tests were performed in conjunction with the grouting design to select the appropriate type of grout and determine the grouting specifications. The successful application of the chemical grouting scheme allowed construction of the new tunnels with a minimum impact on the existing tunnel.