Geotechnical Characterization of Hard Till for Pile Driving

ABSTRACT: Hard till is encountered through most of Canada. The most common tool in the geotechnical investigation is the standard penetration test. In hard till, SPT usually reaches refusal, with limited split spoon penetration. The material can have a wide range of composition but is predominantly cohesive in nature. Hard till is difficult to sample with a Shelby tube sampler and often results in a limited and highly disturbed sample recoveries. Often hard till profiles end up with sparse data or sometimes even no data. Better sampling techniques and in situ testing are required for realistic characterization of hard till. For the installation of deep foundation systems using driven piles, a realistic estimate of resistance to driving is required in order to select a suitable pile driving hammer(s) for successful installation of the foundation system. Results from fully instrumented pile testing is utilized here to provide some insight into the response of “hard” till to pile driving and pile load applications.