Tunnels & Shafts

Design of building foundations which overly tunnels requires detailed analysis of initial ground stresses acting on the tunnel and the added stress from building construction. Numerical modeling is often performed to compute the additional stress imposed on the tunnel liner. MRCE has designed foundations supporting many structures within the influence of transit tunnels in New York City and Washington, DC, and manages construction around utility pipes and small diameter tunnels.

  • Tunnels
    Tunnels structures inserted into the ground by jacking, horizontal drilling, or mining come into intimate contact with the existing ground on construction, and rely on documented geotechnical conditions for method and equipment selection. Ground stresses change with time as the soil relaxes to contact the tunnel wall. Cut and cover tunnels, where precast pipe or cast-in-place box structures are constructed within an earth cut, are separated from the existing ground by drainage stone and soil backfill. Cut and cover structures require efficient excavation bracing design for rapid construction advancement.
    MRCE tunnel design experience includes mined tunnels, horizontal drilling, small diameter boring machines, pipe jacking, and expansion of existing tunnel clearance and new liner structures. MRCE drilling inspection, sampling, and soils and rock laboratory testing contribute to tunnel alignment selection, liner designs, and construction contract documents.
    MRCE tunnel project experience covers a wide range of tunnel contract needs, including:

    • Feasibility studies and alternative alignment studies
    • Tunneling method evaluation (NATM, TBM, Shield Driven, Drill and Blast and Raised Bore)
    • Mined and Bored Tunnels. Tunnels with rock blasting.
    • Soft ground tunnels and Mixed Face Tunnels
    • Jacking, and jacking pits
    • Cut and Cover structures
    • Microtunneling
    • Horizontal Directional Drilling (HDD)
  • Shafts
    Shafts provide access to tunnels and deep pipe networks, but also enable construction of underground structures such as escalators to subway stations, for ventilation, to launch and retrieve tunnel boring machines, or facilitate jacked tunnel construction. MRCE is familiar with the many ways shaft structures are constructed and tailors design and construction documents for each: frozen ground and deep soil mixing which provide a temporary support to enable cast-in-place permanent shaft construction, and slurry wall diaphragm walls and secant pile walls which become the permanent shaft structure.

Con Edison Harlem River Utilidor Tunnel

Southern Reinforcement Project: Underground Transmission Line

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