In a certain region of H-piles subjected to ground water table fluctuation, painting is sometimes applied on the surface of H-piles because the rise and fall of water table contribute to the corrosion of H-piles.
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In a certain region of H-piles subjected to ground water table fluctuation, painting is sometimes applied on the surface of H-piles because the rise and fall of water table contribute to the corrosion of H-piles.
When piles are driven through an upper layer of granular soils, thick (10mm) bitumen layer would be scrapped off during the driving process. A thin coat of 1mm to 2 mm thick is not likely to flow in storage and to peel off during pie driving.
The change in pore water pressure varies in different soils. In loose sands and sandy silts, the pore water pressure increases during pile driving owing to soil densification. The increase in pore water pressure reduces the soil strength. However, after piling operation ceases for a certain period of time, upon dissipation of pore water pressure the soils would result in increased strength by soil “set-up”.
Hammer efficiency refers to the ratio of kinetic energy of the hammer to the rated energy (or potential energy). In essence, it is undoubtedly that certain energy losses are induced by the hammer itself prior to the actual impact on the driven piles. For instance, these losses may include the misalignment of the hammer, energy losses due to guiding friction, inaccurate dropping height etc
A follower is an extension between the pile head and the hammer that transfers the blow to the pile in which the pile head cannot be reached by the hammer or is under water .For construction of driven piles, the piling frame and hammer are normally erected on existing ground level but not at the base of pile caps.
Hiley’s formula R=E/(s+0.5c) is based on the principle of energy conservation in which the energy brought about by hammers during the action of hitting are transferred to piles in ground. When the hammer force and displacement is plotted, the energy absorbed by piles is the area under the curve.
About 90% of H-piles adopt Hiley’s formula for design. However, this formula is only applicable to pile lengths less than 30m and is suitable for course-grained materials (not suitable to fine-grained soils) as suggested by GEO (1996). In Hiley’s formula, by observing the penetration of piles after the hammer impact, the pile capacity could be readily obtained from the response of the impacting force. Therefore, the individual pile capacity could be obtained by this dynamic method.
Planning & Engineering often go together like cats and dogs, conservatives and liberals, or oil and water. This series of educational articles that will teach you about new opportunities for engineers who embrace planning – a new era of preferred living standards called, Prefurbia.
Providing for Surface Drainage through more efficient planning:
Planning and engineering merge when creating ‘green’ solutions, including proven methods such as surface storm water flow (that is also affordable compared to piped flow).
Nature has provided land with flow that has evolved over time. However, typical urban and suburban development patterns destroy millions of years of evolution. It’s most efficient to keep surface flow as close to the natural system as possible – the best solution from both economic and environmental perspectives.
When a hammer with initial motion collides with a stationary pile, the transfer of energy is most efficient when the two masses are comparable. That is the reason why some codes limit the ratio of weight of hammer to the weight of pile to be more than 0.5.
Boussinesq’s closed form solution for a rod fixed at its end and hit on its top by a mass shows that compressive stress in the rod increases with the mass of hammer. On the other hand, a larger relative mass of hammer leads to lower tension stress. When an impact is made on friction pile, the compressive stresses are highest at pile top. When an impact is made on end-bearing pile, the compressive stresses may be highest at the top or the bottom of the pile.