The Footprint Engineering Combined Modulus Pile (FeCMPile) is a method of forming an elongated support column in the ground. Specifically, our method comprises of drilling a hole of a predetermined depth and diameter.
The bottom of the drilled hole is then filled with 3 to 8 feet of gravel. A hollow driving tube with several pre-cut holes at the bottom near a welded end cap is then used to compress the ground below the gravel as it is inserted into the drilled hole with the gravel below the column to secure the driving tube in place. Essentially, the base and shaft friction are mobilized together in “drill open soil” conditions. Once the driving tube is secured in place and plumbed, liquid concrete is then poured into the top end of the driving tube. The concrete that accumulates at the bottom end of the driving tube then passes through the radial apertures onto exposed gravel and into a space between an exterior wall of the drilled hole and the soil wall.
The driving tube and gravel become one, thus allowing it to be considered as a single entity which is friction fit into the hole. As such, the pile is robust to pull-out, and superior in down load resistance as greater shearing forces at the hole/pile, and pipe/gravel interfaces combine to move as one combined modulus unit. This then ensures that capacities in the range of 100-250 tons are achieved.