Foundation Repair With Micropiles
As we mentioned before there are two major types of piers to lift foundations and stabilize the structure in most residential and commercial foundation repair jobs. Push/Resistance Piers and Helical Piers/Piles are the primary solution for most structures. There are times however when these won't work because of conditions or the capacity required is too large for these types of piers. On this page we will focus on Micropiles or minipiles.
Micropiles like other piers are attached to the foundation based on the engineering requirements of the structure. Allowable micropile capacities in excess of 1,000 tons have been achieved. They have been used since the early 1950s to underpin historic buildings and monuments in Italy.
The micropile casing generally has a diameter in the range of 3 to 10 inches. Typically, the casing is installed to the design depth using a drilling technique. Reinforcing steel in the form of an all-thread bar is typically inserted into the micropile casing. High-strength cement grout is then pumped into the casing. The casing may extend to the full depth or terminate above the bond zone with the reinforcing bar extending to the full depth.
The finished micropile resists compressive, uplift/tension and lateral loads and can be load tested like any other piers. The pile integrates completely with the soil. It forms a foundation system of reinforced soil mass, in particular if placed in groups.
Many companies offering this type of installation have micropile drill rigs allow installation in restricted access, low headroom interiors, permitting facility upgrades with minimal disruption to normal operations.
Advantages of Micropiles
- Reinforces the Soil
- Drilling minizes disturbance to the ground and nearby sensitive structures.
- Larger capacity than traditional piering methods
- Higher Cost of Foundation Repair
- Requires more equipment
- Could take longer to complete
Micropiles are a great alternative for the situations where a normal piering system just won't do. Unless the soil is so bad (almost liquid like) or you have an incredibly heavy structure it is doubtful you would see this method used in Missouri because of the cost difference.