Use of micropiles in Southern Ontario

ABSTRACT: Application of gravity-grouted and pressure-grouted micropiles at four sites in Southern Ontario is presented in this paper. The design methods for micropiles are reviewed and discussed. The design load varied from 400 to 800 kN for micropiles with lengths of 11.5 to 25 m and drillhole diameters of 150 to 320 mm. Challenges associated with the micropile installation in saturated cohesionless soils are also addressed. The load testing methods and results are discussed. The bond strength of grout-ground and load transfer back-calculated from the verification/performance tests are correlated to the soil conditions and micropile installation methods. Typical values of micropile bond capacity are recommended.