1005. 3(b) 1005. 3(b) refusal is reached if the penetration for ten additional blows is 1/2 inch or less. After the pile tip enters the intended bearing stratum, if an unreasonably l arge number of blows is required to increase the driving resistance from 10 blows per 1 inch to 20 blows per 1 inch, the Structure Control Engineer may waive the requirement for driving to absolute refusal.
The Structure Control Engineer will determine the acceptability of piles that do not achieve absolute refusal and capacity at the predetermined pile tip elevation for piles intended to bear in soft or decomposed bedrock. If piles are determined unacceptabl e, continue driving piles to Case 2 Absolute Refusal to ensure absolute refusal is obtained. The Structure Control Engineer will contact the BDTD to revise the Pile Hammer Approval Letter for differing site conditions if the continued driving exceeds the c riteria provided.
Case 3. Piles Which Attain Absolute Refusal Above Predetermined Pile Tip Elevations. If hard driving is encountered because of dense strata or because of obstructions located above the bearing stratum identified by a predetermined pile tip elevation, absolute refusal is not reached until the Structure Control Engineer determines the total number of blows, as the average driving resistance specified for absolute refusal, indicates further driving will not advance the pile through the dense strata or obstructions. The Structure Control Engineer will verify the driven pile tip elevation is at or below the minimum embedment length indicated.
The Structure Control Engineer will contact the District Bridge Unit to determine the acceptability of piles that attain absolute refusal above the predetermined pile tip elevation. If piles are determined to be unacceptable, drive one or more production piles at locations directed. If the additional piles also fail to reach the predetermined pile tip elevation, and if directed, drive additional test piles to determine whether the predetermined pile tip elevation may have to be adjusted. Perform test borings and pile load tests, if directed. Perform augering, predrilling, spudding, preexcavation, or jetting, if directed. The Structure Control Engineer will contact the BDTD to revise the Pile Hammer Approval Letter for differing site conditions if necessary .
If production piles attain absolute refusal above the predetermined pile tip elevation due to freezing resulting from discontinuous driving, the Structure Control Engineer will reject the piles. 5 .b End of Driving Criteria. For end bearing and friction piles terminating in soil , end of driving criteria is reached if the required capacity is attained , and the pile tip reaches the predetermined elevation in the intended bearing stratum. Dynamic pile load testing w