What are the key considerations in drilled shaft construction?

Drilled shaft considerations: (1) Excavation method - auger drilling for soil, rock sockets require special tools, (2) Stability during drilling - casing, polymer slurry, or bentonite for unstable soils/water, (3) Base inspection - cleanliness critical for end bearing, inspection with camera or ultrasonic testing, (4) Concrete placement - tremie method under water/slurry, free fall for dry holes, (5) Quality assurance - cross-hole sonic logging, thermal integrity profiling for defect detection. Shaft capacity can be verified by load testing (O-cell, static, or dynamic).