Micropile Installation

Micropiles are used to support new building structures where conventional pile installations are not accessible. This method uses hydraulic pusher to push short piles deep into the ground piece by piece until it hit rock or solid base underneath. The process starts with forming beam structures which will support the new building. A pair of c-shape steel bars are then vertically welded to the beam structures. This pair of c-shape bar extends from the beam structure up above the ground level into the air. The whole new building structures is then completely constructed including the walls and roof. The c-shape bars are usually located at the corners inside the new building as shown in the picture below.

A hydraulic pusher support is then attached to the c-shape steel bars. A hydraulic cylinder is installed on the support. Hydraulic hoses are then used to connect the hydraulic cylinder to the hydraulic pumps (blue machine below).

The micropiles are steel tubes with a diameter of 4 inches. Both ends of the first micropile to be pushed into the ground need be closed by welding and trimming a sheet of steel at the openning. This first micropile is then inserted in between the ground and the hydraulic pusher and pushed into the ground until its upper end is about 1 foot long above the ground. At the upper end of the first micropile, a short section of the steel tube is cut out and used as an inner connector between this micropile and the next one. In order to slicely reduce its diameter, a part of the connector's side wall is cut away resulting in a c-shape short tube. The connector is inserted and welded into the upper end of the first micropile. The next micropile is now inserted in between the first micropile and the hydraulic pusher. Both micropiles are welded together and driven into the ground by the hydraulic pusher until the upper end of the second micropile is about 1 foot long above the ground. The cycles of making c-shape connectors, joining micropiles together and driving them into the ground are repeated until the first micropile hits the unbreakable rock or solid base. The end of pusing cycle can be observed when the pusher can no longer drive the micropiles into the ground but start moving up the bulding structures instead. During the short instant when the bulding structures are moved up, some small crack damages might occur at various areas of the building but they can be fixed later.

After the end of pushing, the remaining part of the last micropile is cut and a piece of C-shape steel bar is then used to connect it with the two vertical beams. Finally the embedded micropiles and the beam hole are completely filled with cement.