The Use of BDSLT for Design of Large Capacity Cast-In-Place Piles

Cast-in-place concrete piles socketed in rock are a commonly used foundation solution in the province of Ontario. Although cast-in-place concrete piles are common, limited pile load testing has been undertaken on these foundations to confirm shaft friction (side shear) and end bearing parameters. Particularly, the large diameter piles bearing on rock makes conventional pile loads tests impractical and costly due to large capacities that need to be mobilized during testing. Performance of piles loads test come with the advantage of confirming the assumed geotechnical design parameters and permitting the use the larger strength reduction factor as per LRFD design. This paper presents the preparation, execution, and result interpretation of a pile load test carried out on two Cast-in-place concrete piles with diameters of 1.5m and 1.8m for Garden City Skyway Project in the City of St Catherines Ontario, Canada. The 1.5m and 1.8m diameter test piles were socketed 4m and 6m into shale bedrock. Osterberg cells were used in both load tests to provide end bearing and shaft friction parameters for the shale bedrock as well as overlying layers of till and soft clay. The results of the load test provided valuable insight into the load settlement performance exhibited by these piles. The results are also compared with the analytical estimates of the pile capacities presented in geotechnical report as well as the results of a number of other analytical socket design approaches.