Foundation Project Featuring an Air Pile Driver Mounted onto an Excavator
Project
This customer originally tried to drive sheet pile with a vibratory hammer mounted to an excavator for erosion control and support of excavation.
The soil conditions proved to be too harsh for the vibratory hammer to drive the pile successfully.
It was apparent that the sheet pile had to be driven with an impact hammer in order for the sheets to reach the specified depth required by the engineering plans for the job.
Solution
The customer decided to use an air pile driver mounted to an excavator to complete the job. The impact hammer chosen was an MKT 11B3 air pile hammer which weighs 19,150 lbs and delivers 14,200 ft-lbs of striking energy.
Certain lightweight hammers with lower striking energy can hang freely from the end of the excavator arm without much hammer damage or safety risk.
This job required a heavy impact hammer which cannot be free hung due to safety concerns and extremely high risk of damage to the hammer.
Spud clips were fabricated to the back of the hammer and a spud beam was fabricated to pin the beam to the excavator arm.
This design is substantial enough to support the weight of the hammer during operation.
Successful Outcome
The MKT 11B3 air pile driver successfully drove the sheet pile to the required depth. The customer found that the cost and the speed of the pile driving equipment setup were not satisfactory for his job for the following reasons:
- The cost to fabricate the spud clips and the spud beam were disproportionately high compared to the durability of the setup. The immense impact strength of the air pile driver put so much torque on the spud beam that it was damaged beyond repair after the job and not able to be used again for future projects.
- Accessories needed for this setup such as an air compressor, air hoses, and lubricator were cumbersome and costly. Freight charges and rental charges for this equipment added to the cost on the job. Positioning and maintaining all of this equipment on-site proved to be time consuming.
- The pile driving equipment setup drove the piles slowly because it was difficult to control. Its fixed position on the spud beam caused reach issues. The hammer could not reach high enough at the beginning of the pile and the hammer could not drop down low enough at the end of the pile. These problems caused delays and resulted in higher costs for the customer.
Although this pile driving gear got the job done, it was not the best solution possible. The customer will consider using a pile driving rig such as the CZM EK125HH in the future for a better profit margin and faster completion speed on his job.
