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Abstract: Precast segmental linings are increasingly used in the mechanized tunneling methods using TBM- bored shield tunnels. Tunnel segments are designed following the approach of limit state design recommended by national and international codes and guidelines. Ultimate limit state (ULS) and serviceability limit state (SLS) are specified in these design codes. The former focuses mostly on the ultimate...
Abstract: Watertightness of tunnels must be ensured during design and construction in order to prevent water infiltration, minimize maintenance and repair costs, maintain operational safety, and protect mechanical and electrical equipment inside tunnels. One-pass segmental lining system nowadays is the most commonly-used system in TBM bored tunnels. In these tunnels, the watertightness is guaranteed by...
Abstract: Methods for analysis and design of segmental tunnel linings are presented inconformance with standards and guidelines from Austria (ÖVBB), France (AFTES), Germany(DAUB), Japan (JSCE), Netherland, United States (FHWA) and International Tunneling Association(ITA). Effect of embedment loads on segments is analyzed using elastic equations, a beam-springmodel, and Finite Element or Finite Difference...
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: 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: 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...