Micropiles (also referred to as Mini-Piles) are deep foundation, small diameter grouted piles typically consisting of a central steel reinforcement member and commonly includes steel casing. Micropiles can be designed to carry very high capacity loads, with design loads commonly on the order of 250 kips and higher depending on project requirements.
Loads are typically achieved through skin friction between the grout and surrounding soil or rock. In limited situations, loads can be achieved in end-bearing where the piles are terminated incompetent rock formations. Unlike a Drilled Pier, Micropiles derive a large percentage of their load from the steel reinforcement. This, coupled with achieving their load in skin friction, makes micropiles excellent for both tension and compression loads. Steel casing can also be added to address lateral loading requirements.
Micropiles are typically used in limited access areas, such as low overhead clearance, and can be accessed through a typical man door. Micropiles are a cost effective solution in areas with Karst topography and sloping rock.
With a typical Drilled Pier foundation, significant cost overruns can occur due to extra rock coring. This is resulted as the Drilled Piers are extended along the face of sloping rock, or when voids are encountered in the rock formation near the design bearing elevation of the drilled piers and extra rock coring is required. Micropiles reduce this risk as micropiles typically extend down into the rock formation so the load is transferred in skin friction and potential voids in the rock are identified. This eliminates the risk of voids below the bottom of the Drilled Pier.
Want to know if micropiles are the best fit for your job? Check out our previous micropile deep foundations in the Related Case Histories to the right, or call us today at 800-246-9721.
Micropiles can be used in a variety of applications. Particularly useful when projects are launched in areas with limited access or weak soil, Micropiles have become a preferred method of deep foundation stabilization for their reliability, versatility, and efficiency.
Before you can decide if Micropiles are the best option for your project, it’s important to understand how they work and are applied. For an overview of Micropiles, their components, and practical uses, review this brief guide:
Micropiles can be used on a variety of projects, including the fortification or creation of foundations for bridges, towers, and new buildings. The versatility of Micropiles has led to their increased popularity and their use in tough construction conditions. When faced with areas of low clearance, restricted access, or collapsing soil types, Micropiles are an ideal solution.
When compared to other foundation products, Micropiles are customizable and cost efficient and they eliminate the need for additional steps during installation. Because Micropile installation can be completed without pre-drilling, project completion time is not compromised. Micropiles offer the following features and capabilities:
Micropile specifications need to be tailored to fit the requirements of your project. Helitech Civil Construction engineers can help you find the product that fits your needs for load capacity, material, and ideal use.
Each part of a Micropile works together to reinforce the strength of a foundation system. Available in cased and uncased varieties, Micropiles typically include the following parts.
Micropiles are available in multiple varieties, but all are cost-efficient, quick to install, and usable in limited access or low-headroom areas. For help in determining the type of Micropile that is best for your project based on your specific needs, contact a Helitech Civil Construction Division representative today.
In the past 20 years, Micropiles have grown in popularity among contractors and foundation specialists. Here are a few examples of successful Micropile applications from Helitech Civil Construction Division’s satisfied customers.
New York, Ohio, Oklahoma, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Virginia, Wisconsin, West Virginia, Wyoming, Washington DC, Alabama, Arkansas, Colorado, Delaware, Florida, Georgia, Iowa, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, Mississippi, North Carolina, North Dakota, Nebraska, and New Jersey.
Chance Helical Pulldown Micropiles are used to form a grout column around the shaft of a standard helical anchor/pile. The installation process can employ grout only or grout in combination with either steel or PVC casing.
Benefits of Pulldown Micropiles include: Resistance to buckling in weak surface soils; Stiffer pile (deflects less at a particular load); Additional corrosion protection in aggressive soils.
Rock Anchors are structural members used to provide temporary or permanent resistance to a structural element by pre-loading and locking-in tension load. These anchors are installed by drilling into the rock and resistance loads are achieved by the development of friction between rock and grout interface. The structural member (reinforcement) is typically either solid bar or strand anchor that is set into the drilled hole and grout is applied by tremie the method.