Versatile ABI Mobilram Systems Offer Mobility, Accuracy and Speed

Lakes & Rivers Contracting Beats Own Estimates with Mobilram

The mobility, accuracy and high production capabilities of the TM-13/16 Mobilram system helped Lakes & Rivers Contracting, Inc. to beat its own production estimates for a job at the Oak Meadows golf course in Addison, Illinois. The ABI Mobilram system offered high performance and finesse for driving the light sheet piling sections without damage. In addition, the system is known for its accuracy.

Hired to install sheet piling for retaining walls around the golf course's island greens, Lakes & Rivers Contracting found that the TM-13/16 permitted fast, accurate placement, despite the intricate shapes of the piling configuration around the greens. The final product was so exact that pile cap manufactured offsite and pre-rolled to specific dimensions fit precisely over the top of the piling. The company installed approximately 1200 wall feet of LZ-250 cold-formed steel sheet piling.

The contractor also used the TM-13/16 to drive HP10x42 bearing piles for 12 new cart path bridges throughout the course. Despite the fact that these were widely scattered, the mobility of the ABI system allowed the task to be accomplished faster than expected.

O'Neil Brothers Construction Tried It, Liked It, Used It Again

O'Neil Brothers Construction Co., Inc. first used the Mobilram ABI TM-13/16 system for a job in Champaign, Illinois, where a tight workspace area did not allow for the use of a conventional crane suspended pile driver. They were so pleased with its performance that they selected the TM-13/16 a second time for an apartment building project also in Champaign. On that project, approximately 1100 wall feet of 5-gauge steel sheet piling was installed for soil retention and to act as the outside form wall for the parking structure foundation.

The O'Neil Brothers' crew took full advantage of the system's placement accuracy. Since the TM-13/16 offers such close tolerances, it can be operated without the use of piling templates, O'Neil Brothers simply pulled a string line and drove sheets along it.

ABI Rigs Reduce Noise, Vibrations

When working on a building in a downtown area, noise and vibration are always important considerations. For these reasons, Foundation Contractors, Inc. and Schnabel Foundation Co. looked to ABI for drilling and vibratory driving systems for work on the new CALPERS building in Sacramento, California. The project included the installation of 1600 auger cast piles and 600 vertical tie downs or vibropiles with ABI Mobilram Systems.

A vibropile is a closed-off casing that is vibrated into the ground, displacing and densifying all the material in its path. Grout is pumped through the bottom of the casing during extraction. Using ABI's variable moment high frequency vibratory driver and crowd forces, vibropiles were installed to depths 20 to 30 feet while the vibratory driver operated at roughly 30% of capacity. Each hole was completed in 10 minutes, of which vibration times were only two to three minutes. The variable moment and high frequency features of the driver minimized vibrations transmitted to the surrounding soils.

The auger cast piles on the project were equally challenging. The top 35 feet of the 50-foot pile were in running sands and water, while the last 15 feet were in gravels and cobbles with blow counts up to 80-90 blows/ft. A "casing twister" was used, allowing a hollow, continuous flight auger (CFA) and casing to be drilled simultaneously. Using this system, Foundation Contractors installed an average of twenty-five, 50-foot cased holes (1250 feet) each day.

Vibropile Advantages:

• High production, low cost, superior piles.
• No spoils are removed from the ground.
• Soils are densified around the pile, providing more bearing and lateral load capacity.
• Casing/probe hole is sealed. There is no possibility of contamination of the pile.
• Pile foot is flat, giving a higher end bearing load capacity.
• Pile diameter can be expanded through pumping grout under pressure while withdrawing the relatively small diameter probe.

Casing Twister Advantages:

• Fast installation of high quality piles.
• Due to the support of the casing, the auger flight can be crowded, resulting in good production for both hard and soft ground conditions.
• As pile tip is reached and the penetration slowed, the running sands above do not feed the auger and therefore do not create a larger hole than desired.
• Casing ensures a straighter hole, augers used alone can flex more easily.
• Once the hole has been completed, the spoils of the auger are simply reversed, collecting all the material at the bottom of the auger rather than spinning the auger at high speed dangerously spraying the job site with spoils.