Soldier piles and lagging is a commonly used excavation support system. Steel piles are installed in a vertically drilled hole and embedded below the excavation depth to provide the necessary passive resistance. Timber lagging is typically either installed behind or clipped to the front flange of the pile to support the soil behind the excavation and transfer the load to the piles. Piles can be cantilevered or braced with walers, rakers, struts and/or tiebacks.
Advantages of pile and lagging systems:
- Cost effective in comparison to other shoring systems in suitable soils
- Less vertical drilling requirements vs. caisson walls
Challenges associated with pile and lagging systems:
- Often limited to temporary construction
- Cannot be used in high water table conditions (in wet to saturated soils) without dewatering
- Not suitable in granular (non-cohesive) materials as sufficient cohesion is required to allow for soil arching between the piles for the soil to stand vertically
- Poor backfilling and associated ground losses can result in surface settlements
- Susceptibility to ground loss and wood rot limits use adjacent to existing buildings and other sensitive infrastructure
- Rate of excavation can be impacted in challenging, less suitable soils
- Not as rigid as other shoring systems can result in greater lateral movements
The HCM Group commonly utilizes a design-build approach, working closely with RWH Engineering Inc., to provide shoring solutions specifically tailored to meet the project’s requirements. Our closely integrated project management and in-house engineering allows for timely submissions and real-time on-site problem solving.
The HCM Group continues to invest in the right equipment to meet our customer’s requirements. We feel confident that our innovation and design-build approach to foundation contracting will provide benefits to your next project.