Abstract
Geotechnical drilling is a common part of site investigations prior to marine construction. A small, solid core is extracted from shallow depth for examination at the surface. During standard penetration testing (SPT), a sample tube is hammered into the ground at the bottom of the borehole. The number of blows needed for the tube to penetrate a fixed depth relates to the hardness of the ground and is termed the standard penetration resistance. Recordings of the drilling and SPT operations of a jack-up rig situated in 12 m of water were obtained with a mobile recording system at 10-50 m range and 10 m depth below the sea surface. Geotechnical drilling (120 kW, 83 mm diameter drill bit, 1500 rpm, 16-17 m drill depth below the seafloor consisting of sand then mudstone) had a radiated noise level (using geometric spreading) of 142-145 dB re 1 μPa rms @ 1 m (30-10,000 Hz). SPT (50 mm outer diameter of the test tube, 15 mm wall thickness, 100 kg hammer, and 1 m drop height) exhibited a radiated noise level of 152-160 dB re 1 μPa2s @ 1 m.
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