The South Hartford Conveyance and Storage Tunnel (SHCST) as a major component of the Hartford Metropolitan District's Clean Water Project is intended to capture and store Combined Sewer Overflows (CSO) from the southern portion of Hartford and Sanitary Sewer Overflows (SSO) from West Hartford and Newington. The 20 ft-diameter, 21,800 ft-long bored tunnel will be excavated in shale, siltstone and basalt through several fault zones with high groundwater pressures up to 9.6 bars. This paper discusses the implementation of the results of the geotechnical discontinuum analyses on the structural design of the tunnel segments for final service stage design as well as other critical load cases occurring during the segment production and transient stages. For the first time in North America, double hooked-end steel fibers (Dramix? 4D) were designed for reinforcement. This new type of steel fiber satisfies the serviceability requirements by limiting time-dependent effects of creep on crack opening and more significantly satisfies ductility requirements by providing an ultimate bending moment higher than the cracking bending moment.
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