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Thatcher has been in business for 60 years. We pride ourselves in our ability to complete projects on time and on budget. We made our reputation building foundations for some of the largest structures in Chicago; however,18 Street Pedestrian Bridge - 100 ton micropiles, 90 ton driven piles. pounding the biggest piece of steel into the ground isn't always the best solution. Sometimes the job can be done using something smaller and less intrusive - a micropile.

Micropile is a misnomer. The typical capacities of a micropile are 20 to 100 tons; in special cases, some are greater than 200 tons. Micropiles were developed in the 1950's in Italy as a means to support historic buildings. Originally called pali radice, they made their way across Europe over the next few years. They first showed up on this side of the Atlantic in the early 1970's in Boston and New York. It wasn't long before people started to realize micropiles might have an application other than underpinning. Construction and material standards were developed and the micropile was on its way.

Micropiles offer advantages over other types of deep foundations:
  • Micropile pile rigs are small and able to get into places other
    deep foundation rigs can't
  • Micropiles are installed in threaded sections of any length.
    This makes micropiles ideal for low headroom installations
  • Micropiles cause minimal vibration and noise
  • Micropiles produce minimal amounts of spoil. The typical micropile
    is five, seven or nine inches in diameter - much smaller than
    other drilled foundations
Micropiles are made of 50 to 80ksi steel casing and 4,000 to 5,000 psi grout. The casing is drilled down to a pre-determined depth or socketed into rock, then tremie-filled with grout.
Here are the most popular sizes, assuming allowable steel stress of 18ksi and 4,000 psi grout:

Diameter (in) Wall Thickness (in) Weight (lbs./ft.) Allowable Load (tons)
5.0 0.362 18.00 56
5.5 0.415 23.00 73
7.0 0.498 35.00 114
9.625 0.545 53.50 186

The typical micropile installation is usually done in conjunction with another type of foundation method. We can assist in the design of the foundation system to minimize cost and potential problems. The earlier we are involved in the process, the more we can help.

Download our Micropiles brochure. Click here

Call us today and let us show you how we can help you complete your project on time and on budget.

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