Mission Blvd/Warren Ave Freight Rail Road Relocation- Fremont, California

Project Highlights

  • Deep Soil Mixing (DSM) Walls reinforced with steel soldier piles were installed for excavation support and groundwater control for the construction of a grade separation structure
  • Reinforced DSM walls were integrated in the design of the permanent structures including retaining walls, and the abutments and pier of the railroad and BART bridges.
  • Warren Avenue Grade Separation is part of the Bay Area Rapid Transit (BART) Extension from Fremont to San Jose, CA.
  • A grade separation structure was proposed to separate traffic from a railroad and future BART rails to mitigate traffic congestion during daily peak hours.
  • The length of the grade separation is approximately 900 ft. with a maximum depth of 28 ft.

Generalized Profile

  • The project site is located in Santa Clara Valley, an alluvial the basin that lies between the active San Andreas fault to the west and the Hayward and Calaveras faults to the east.
  • The subsurface soils generally consist of medium stiff to very stiff lean and fat clay, overlying very stiff to hard lean clay, with occasional interbedded sand layers and lenses at various depths.
  • The natural moisture contents of the soils are typically in the range of 20% to 30%. The soil strength values (Su) range from about 1.25 ksf near the grade separation bottom to about 2.5 to 3.0 ksf at depths.

General Design Considerations

  • Groundwater Control:  Need to cutoff major sand layers/lenses to maintain a dry excavation during construction
  • Lateral Design: Temporary Design/Shoring with Tiebacks and Pipe Struts. Permanent Design with Concrete Struts below grade.
  • Vertical Design: DSM as foundation system for Bridge structures. Capacity governed by side adhesion between DSM and native soil or friction between soldier piles and DSM