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Abstract: The TBM-bored tunnels consist of tapered individual rings that are installed and rotated in a manner that straight and curved alignments are negotiated with the smallest deviation possible from the theoretical alignment. This deviation is an inherent feature of the segmental ring systems because a segmental ring is always built in the shape of a cylinder. Therefore, TBM guidance through a...
Abstract: Tunneling operation in congested urban areas becomes more frequent as demand for further utiliz-ing underground spaces grows. In urban settings, it is not uncommon for tunnel designers to plan a tunnel route in close proximity to other structures to satisfy other competing objectives like rais-ing the alignment to reduce excavation volume. Setting the alignment close to existing structures...
Abstract: Tolerances are the allowable deviations of actual dimensions of segmental lining either as individual components or as a system from their design dimensions. Deviations from the nominal geometry can be accepted when they don’t result in lining damages and don’t negatively impact the intended function and service of the tunnel. On one hand, it is important to achieve the highest possible level...
Abstract: The South Hartford Conveyance and Storage Tunnel (SHCST) is a major component of the Hartford Metropolitan District’s Clean Water Project (CWP). This tunnel is intended to capture and store Combined Sewer Overflows (CSO) from the southern portion of Hartford, CT and Sanitary Sewer Overflows (SSO) from West Hartford and Newington, CT. The project is estimated to cost approximately $500 MM and...
Abstract: This paper discusses the use of numerical modeling for optimization of tunnel rehabilitation scheme to improve the clearance of the Howard Street Tunnel in Baltimore, MD. With a total length of approximately 8,700 feet, the Howard Street Tunnel consists of three sections: concrete box section, original cut-and-cover section, and original mined section. The Howard Street Tunnel currently has a...
Abstract: Segmental tunnel linings installed in the rear of the TBM shield are generally in the shape of circular rings. Size of the ring is defined by the internal diameter, thickness, and length of the ring. These three major geometrical parameters are discussed in details. First, the dimensions of the tunnel inner section are discussed considering the internal space required during the service, which...
Abstract: In modern transit systems, maintaining air quality, environmental control, and Fire Life Safety within the underground portion of the system is an important component of the overall design and its compliance with the established life safety and comfort guidelines and standards. Typical Heating, Ventilation, and Air Conditioning (HVAC) systems do not have sufficient capacity to control the heat...
Abstract: Cracking in tunnel linings is a major cause for reduction in serviceability due to water infiltration and exfiltration, and reinforcement corrosion. In current industry practice, in order to control ground water inflow in lined tunnels, maximum crack width is limited to allowable values in a range of 0.15-0.3 mm specified by the codes, guidelines and recommendations. However, a correlation...