TTC Wilson Complex Modification

TTC Wilson Complex Modification

Engineering Solutions

The Toronto Transit Commission will be purchasing all new subway cars in the near future, creating the requirement of larger maintenance carhouses. The original contract drawings employed caisson wall, soldier piles and lagging, and conventional concrete underpinning for the earthwork specifications related to our field of work. HC Matcon proposed an alternative engineered solution that included the use of shotcrete, underpinning, micropiles, soldier piles and shotcrete lagging (SPSL) to achieve the same effect. The acceptance of this proposal allowed for a substantial cost savings to the owner, as well as a shorter construction schedule for the various contractors involved. Mechanical jacking pits were built where shoring is used as a backform for manholes. Shoring for carhouses below- grade will be used as a backform for foundation walls. The substitution of shotcrete underpinning in lieu of caisson walls will allow for easier access to the tunnel portion of the project. This will allow for less demolition of the existing building and less clearance issues.

The above are just a couple examples of the innovations that HCM Contractors Inc. will use to add value to any project.

Client: Aquicon Construction
Location: Toronto, Ontario

EEEL University of Calgary

EEEL University of Calgary

Zero Ground Loss

This project followed shortly after finishing the Taylor Family Digital Library project, which was in close proximity to this site on the same campus. Design considerations for the foundations were almost identical to the previous project, with the installation of approximately 175 cast-in-place belled piles. Again, this new building was a result of the fast-growing population at the University of Calgary and the demand for specialty studies with emphasis on future global trends such as clean energy and the environment.

The soil conditions, which are typical and uniform throughout the mentioned site, consisted mainly of silty sand and clay till which is ideal for large capacity belled piles.

  • The shafts for the piles were predominantly 900mm, 1000mm, and 1,200mm in diameter.
  • The bells were sized at: 2000mm, 2400mm, 2800mm, 3400mm and 3600mm in diameter.

The average founding depth on this project was approximately 13.0m – 17.0m with the need to protect the upper portion of the pile shafts by using temporary casing approximately 8.0m long. The concrete volumes for single piles ranged between 23 – 26 cubic meters. Among the challenges for HCM on this project was installation of piles in close proximity to a concrete utility tunnel. EllisDon approached HCM with a request for shoring and underpinning on a portion of the tunnel.

HCM proposed a design/build tied-back continuous caisson wall method where special consideration was given to the stated goal of zero ground loss from underneath of the tunnel.

Client: EllisDon Corporation
Location: Calgary, Alberta

Brantford General Hospital

Brantford General Hospital

This innovative project represents the first use of shotcrete shoring in place of caisson walls against a building in Ontario. Caisson walls have typically been utilized duw to low movements from the inherent stiffness of the shoring wall. Soldier Piles and lagging walls may move up to 25 mm if properly designed, while caisson walls will move as little as 4-6mm. The soil was a poorly graded medium grained sand which required special measures, including vertical mini piles for vertical load restraint and face savings (avoid ground loss). A significant savings to the General Contractor resulted and the project was a technicall success, in that the maximum inclinometer movement was 4mm. This 4mm achievement signals a new opportunity for owners and General Contractors as the shotcrete shoring space savings and costs saving is very real. 

This project supported an 8 storey hospital, with critical operating rooms, and the shotcrete shoring solution provided a vibration free installation with no structural damages to the owner’s hospital.

Location: Brantford, Ontario

Customer: Bondfield Construction Company