Bored Piles

Bored piles are cylindrical bodies made of concrete (with or without reinforcement) which are installed in the ground by a variety of methods. They transmit high structural loads into lower, load-bearing soils. When installed in rows or in secant configuration they can form a supporting wall for an excavation pit or cut in the terrain, or block off groundwater. The length, diameter, material, shape and layout of the piles can be varied according to their intended use.

Types of Construction Method

The kelly method is used to produce uncased, partially or fully cased or slurry-supported bored piles. The soil is excavated by a drilling tool mounted at the tip of a telescopic kelly bar. When the fully cased pile technique is used, the insection of the full depth casing is simultaneous to the excavation, until the final depth is reached.

The double rotary system (DRS) links the CFA method with continuous auger to the installation of full casing. The result is a cased bore according to EN 1536, installed with a continuous flight auger. This method is particularly advantageous at high ground water levels and soil layers having a risk of uplifting which require drilling under water load with the kelly method.

The CFA-method is a rotary drilling method which permits high drilling performance (CFA 630, 750, 880 mm). This method employs a continuous flight auger as the drilling tool. When the final depth is reached, concrete is pumped from bottom to top through the hollow stem auger. The reinforcement is installed subsequently, where necessary assisted by vibration.

The FDP-system has a key advantage over the CFA-method in that it transports virtually no drilling spoil to the surface. It is suitable in displaceable soils. The drill rod has an auger as starter, followed by the displacement body and an extension casing. During drilling and extraction, the surrounding soil is displaced. Concreting and reinforcement is executed as in the case of the CFA-pile.

PGF System

The BAUER PGF System (Pressurized Grouted Full Displacement Pile System) is a simple, fast and highly effective deep foundation system. The industrially pre-fabricated piles are made from high-strength ductile cast iron which guarantees a high quality and safe foundation solution. To execute the foundation, each individual pile section is joined together via socket-spigot joint to form a pile shaft of any length. The pile sections are vibrated into the soil by a high frequency impact hammer. After driving, the pile is cut down at exactly the required length. The pile is installed as either an end-bearing, or skin friction pile depending on the soil characteristics. With the time duration of driving process recorded the soil bearing capacity of the different layers can be correlated. Thus, for each single pile an individual pile can be specified to suit the local soil condition.

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