Bore Holes
Construction practice
Assignment 1
For this project we have decided to use bore piles as a foundation. When using bore piles firstly the hole has to be drilled to sufficient design depth, in accordance with plans, using a temporary casing and auger that are situated on a Kelly bar. The temporary casing is installed to the necessary depth, this supports the pile bore through unstable soils. Pile bore extended generally using augers or a digging bucket. Support fluid (benonite) will be added if soils are loose and are generally incohesive at the design depth. Once the design depth has been reached the reinforcement cage is put in place in the hole. The concrete is then placed into the bore using a tremie pipe. As the pile is concreted to the required depth, the casing is then taken out so that it can be used again.
The support fluid, benonite, which is the name given to a certain range of clays, they swell up and turn into a gel type substance when it comes into contact with water. It is perfect for when the piles are in unstable ground.
Advantages of Bore piling * No risk of ground upheaval * Adjacent soil doesn’t get disturbed * In a lot of cases bored piles offer higher capacity with potentially better economic value than that of driven piles * Because there are no vibrations existing piles and structures aren’t affected * A lot less noise pollution than driven piles * There is no need for large excavations * They can be drilled up to 50m in depth
Disadvantages of Bore piling * A specialist must be called in to carry out the work * Risk of “necking” the ground * When a pile is completed at least 24 hours must be allowed before any more piles can be placed in the surrounding area * Enlarged ends cannot be formed in incohesive
Assignment 1
For this project we have decided to use bore piles as a foundation. When using bore piles firstly the hole has to be drilled to sufficient design depth, in accordance with plans, using a temporary casing and auger that are situated on a Kelly bar. The temporary casing is installed to the necessary depth, this supports the pile bore through unstable soils. Pile bore extended generally using augers or a digging bucket. Support fluid (benonite) will be added if soils are loose and are generally incohesive at the design depth. Once the design depth has been reached the reinforcement cage is put in place in the hole. The concrete is then placed into the bore using a tremie pipe. As the pile is concreted to the required depth, the casing is then taken out so that it can be used again.
The support fluid, benonite, which is the name given to a certain range of clays, they swell up and turn into a gel type substance when it comes into contact with water. It is perfect for when the piles are in unstable ground.
Advantages of Bore piling * No risk of ground upheaval * Adjacent soil doesn’t get disturbed * In a lot of cases bored piles offer higher capacity with potentially better economic value than that of driven piles * Because there are no vibrations existing piles and structures aren’t affected * A lot less noise pollution than driven piles * There is no need for large excavations * They can be drilled up to 50m in depth
Disadvantages of Bore piling * A specialist must be called in to carry out the work * Risk of “necking” the ground * When a pile is completed at least 24 hours must be allowed before any more piles can be placed in the surrounding area * Enlarged ends cannot be formed in incohesive