Shoring and Excavation Design

Davies Geotechnical Inc has completed the design of numerous deep excavations within the Lower Mainland, and several in Alberta.  These excavations have ranged in depth from 10 feet to 85 feet below grade level.  Recently (2013 and 2014) we have completed the temporary excavations for the Evergreen Line Project and the Solo District Project in Burnaby.  At a depth of 85 feet the Solo Project is the deepest excavation within the City of Burnaby.

In the design of these excavations Davies Geotechnical Inc. employs state of the art processes and site investigative techniques in order to develop cost effective design solutions for these excavations.

To date Davies Geotechnical Inc. has completed designs and projects using a variety of shoring systems, including:

  • Shotcrete tied back with grouted soil anchors. This system is typically the most cost effective of the shoring solutions.
  • Jet grout cut-off wall tied back with soil anchors.
  • Secant walls reinforced with structural elements and tied back with soil anchors.
  • Sheetpile tied back with soil anchors or braced.
  • Structurally brace shoring systems.

Davies Geotechnical Inc. puts high emphasis on supporting these designs with suitable levels of inspection and testing. This has allowed us to very the capacity of structural elements and to identify changes to ground conditions and be proactive in modifying the design to suit.

Davies Geotechnical Inc. is  one of the Lower Mainlands primary geotechnical consultants with extensive experience and expertise in the design of temporary and permanent soil support and shoring systems.

Paul A. Davies, P,Eng. has over 24 years of experience in the design and monitoring of shoring systems in the Lower Mainland of British Columbia. Mr. Davies is a specialist in this design area and has provided designs for shoring systems in a variety of subsurface conditions, from very soft weak and sensitive clays to denser post glacial soils and bedrock. Mr Davies expertise has been called upon numerous times to provide technical review of excavation designs prepared by other consultants and the in the forensic review of excavation and shoring systems that have undergone failure.

The preparation of a reliable and cost effective design requires diligence and expertise at all phases of the work:

  • Site investigation to evaluate soil conditions, strenghts and groundwater conditions.
  • Modelling to assess the loads upon the proposed shoring system and to evaluate shoring and ground movements.
  • Field review to confirm design assumptions and to test the components of the shoring system. This process is vitally important as it allows the design engineer to review soil conditions during the excavation process as well as allowing the engineer to calbrate the design model with the observations made on the site and test results from the shoring component testing.
  • Monitoring during construction to verify that ground movements and loads within the shoring system match the assumptions of the design model.

Davies Geotechnical Inc. utilize a number of modelling and analytical techniques in the development of a successful shoring design. These can include the following:

  • Limit equilibrium analysis – best suited for granular soils and soils that do not have strain dependent strength.
  • Soil- structure interaction analysis – typically involves modelling the soil and the components of the shoring system as springs. This analysis is used to evaluated loads and deformations within the shoring system.
  • Finite element modelling – this analysis is typically reserved for sites with soils that consist of soft clays or sensitive clays where the shear strength of the soil is strain dependent.