I worked in Communication and Works department for 3 months in 2015. I have experience in highway bridge in which I studied Surveying, Pile boring process and Concreting. Bored piling is a method that involves boring a circular hole into the ground, installing steel reinforcement and filling the bore hole with concrete to form a pile. Boring is carried out to the design depth by means of either a crane mounted or a track mounted hydraulic drilling rigs.
In bridge construction work I studied the process of pile boring as Installing a bored pile starts with drilling a vertical hole into the soil, using a bored piling machine. The machine can be outfitted with specially designed drilling tools, buckets, and grabs to remove the soil and rock. Piles can be drilled to a depth of up to 60 meters and a diameter of up to 2.4 meters. The drilling process may include driving a temporary steel cylinder, or sleeve, into the soil. This remains in place in the upper portion of the hole until the pile is poured.
Once the hole is drilled, a structure of reinforcing steel rebar is built and lowered into the hole, then the hole is filled with concrete. The top of the pile may be capped with a footing or pier near ground level to support the structure above. Like any other deep foundation system, bored piles present challenges for the contractor. Because the drilling method used depends on the soil type, the contractor must complete a thorough soil investigation and report. The piling contractor relies on the soil report and past experience to choose the best drilling method that will minimize disturbance of the surrounding soil.
When the soil is cohesion-less, such as with sand, gravel, and silt, or the hole extends below the water table, the hole must be supported using steel cages or stabilizing mud, such as bentonite suspension. This solution can be a very messy process and add considerable complexity to the project.