For cross-hole sonic logging, what is the recommended number of tubes relative to the shaft diameter?
PDI suggests that engineers follow the most current ASTM D6760 recommendation. The standard recommends that for every 250 to 300 mm of pile diameter use one tube. For an engineer to adhere to the recommendation, at least 3 tubes must be used. Using more than 8 tubes will yield little additional information. As a result, 8 tubes is the suggested maximum.