Development of an Extruded Tunnel Lining System

The objective of this report was to design, develop, fabricate, test and demonstrate a system for placing a continuously extruded tunnel liner. The Extruded Tunnel Lining System (ETLS) is a process for continuous slipforming of a concrete tunnel lining directly behind a tunnel boring machine. The program was carried out in three phases. This present report describes the results of the work conducted during Phases II and III (July 1979-June 1983). It includes the design, fabrication and evaluation of a full-scale, 10-foot diameter in an above ground tunnel test facility. The facility consists of: a 10-foot diameter, 22 foot long steel "tunnel"; an ETLS; a "TBM" reaction structure; and concrete mixing and pumping equipment. The ETLS consists of: a 9 foot diameter, 10 foot long, 1 in. thick steel cylindrical slipform; a 9.5 foot diameter, 8 in. wide by 6 in. thick independent annular bulkhead; hydraulic actuators controlling slipform and bulkhead motions; and an electro-hydraulic system for controlling the hydraulic actuators. The rapid set/rapid strength gain concrete mix design has been finalized to achieve 1-1/2 hr strength of 1000 psi while maintaining workability for 30 minutes. Tests of the ETLS have been carried out at advance rates of 4, 6, and 7 feet per hour. In all cases, a competent, self-supporting liner has been produced. Data acquired during these tests have provided a better understanding of the first underground system. Data acquired during these tests have provided a better understanding of the first underground system. Data have included mechanical loading on ETLS components due to form drag, buoyancy, and deviation from alignment; concrete pressures and concrete strength/time properties; and behavior of the ETLS control system. These have been incorporated into a conceptual design based on the information generated during this test program.