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The suction caissons are in many cases easier to install than piles, which must be driven (hammered) into the ground with a pile driver. [4] Mooring lines are usually attached to the side of the suction caisson at the optimal load attachment point, which must be calculated for each caisson. Once installed, the caisson acts much like a short ...
It is used in conditions where the surface soil's load-bearing capacity is less than the anticipated design loads. A grade beam differs from a wall footing because a grade beam is designed for bending and typically spans between pile caps or caissons, while a wall footing bears on soil and transmits the weight of the wall directly into the ground.
Schematic cross section of a pressurized caisson. In geotechnical engineering, a caisson (/ ˈ k eɪ s ən,-s ɒ n /; borrowed from French caisson 'box', from Italian cassone 'large box', an augmentative of cassa) is a watertight retaining structure [1] used, for example, to work on the foundations of a bridge pier, for the construction of a concrete dam, [2] or for the repair of ships.
Also called caissons, drilled shafts, drilled piers, cast-in-drilled-hole piles (CIDH piles) or cast-in-situ piles, a borehole is drilled into the ground, then concrete (and often some sort of reinforcing) is placed into the borehole to form the pile. Rotary boring techniques allow larger diameter piles than any other piling method and permit ...
The caisson provides buoyancy during construction and towing and acts also as a foundation structure in the operation phase. Furthermore, the caisson could be used as storage volume for oil or other liquids. [1] Floating units may be held in position by anchored wires or chains in a spread mooring pattern.
Dynamic load testing takes a further step in analyzing the data and computing static capacity and resistance distribution. Dynamic pile monitoring takes advantage of the fact that, for driven piles, it is possible to compute the energy delivered to the pile, compression stresses at the pile top and toe and tension stresses along the shaft.
Performance testing is a more reliable method of predicting the load-elongation behavior, and is conducted on a selected number of tiebacks in a project. For performance testing, a particular sequence of increasing and decreasing loads are applied, using equipment similar to those used in the proof test.
Casing placement is selected so that the hydrostatic pressure of the drilling fluid remains at a pressure level that is between formation pore pressures and fracture pressures. [ 6 ] [ 5 ] In order to reduce cost, a liner may be used which extends just above the shoe (bottom) of the previous casing interval and hung off downhole rather than at ...