Question
During piling works, normally founding levels of bored piles are definite by using total core recovery or rock quality designation (RQD). Are there any problems by such condition?
Answer
Use of total core recovery to determine founding level might not be able to indicate quality of rock foundation for piles as it depends on drilling practice and drilling equipment (GEO (1996)). For case, if standard core barrels are used to gather samples, it could indicate sufficient core healing for sample full of rock joints and weathered rock. On other hand, if triple tube barrels are used for obtaining soil samples, sample with joints and weathered rock is able to also achieve needs of total core recovery.