Capacity Control, Modeling of Pile Head Stiffness, and Mitigation Measures to Increase Pile Capacity
The capacity of a pile foundation should be considered in all phases of its lifetime, including transportation, lifting, installation
- PDF / 627,077 Bytes
- 16 Pages / 439.37 x 666.142 pts Page_size
- 96 Downloads / 208 Views
Capacity Control, Modeling of Pile Head Stiffness, and Mitigation Measures to Increase Pile Capacity
15.1
Capacity Control of Pile Foundations
The capacity of a pile foundation should be considered in all phases of its lifetime, including transportation, lifting, installation (e.g., pile driving), in-place performance, and even removal phase. The pile foundation should be checked with respect to the pile strength (yielding and buckling), axial and lateral capacity (both static and cyclic), deflections and rotations, as well as capacity of pile–structure connections (e.g., strength of pile sleeves and grout between sleeves and piles, pile grout capacity, etc.). Obviously, the most important phase among the above is the in-place performance, i.e., the performance during the service of pile foundations carrying superstructures. In this phase, pile foundation designs should consider the following issues: 1. Piles should, in general, penetrate all soil layers that can potentially liquefy during a design earthquake event or under ocean wave loading. If soil layers having liquefaction potential are below the foundation tip (bottom), a punching shear analysis should be performed to check the possible penetration of the foundation into the liquefiable soil. In the application of end-bearing piles, it is important to know the shear strength of unliquefiable soil below the bottom of piles as well as vertical distance from pile tip to liquefiable soil layer(s). 2. The lateral resistance capacity (Chap. 16), the axial capacity (Chap. 17), and the torsional resistance capacity (Chap. 18) along piles should be sufficient with an adequate margin of safety against failure. 3. If soils at some depths around piles (relevant to pile–soil capacity control) reach their ultimate load-carrying capacity, the soil plasticity should be kept localized and not be developed into a large portion of piles. 4. The strength and stiffness of piles themselves should be sufficient. 5. The deflection of piles subject to design loads should not be larger than the tolerable deflection. © Springer International Publishing AG 2018 J. Jia, Soil Dynamics and Foundation Modeling, https://doi.org/10.1007/978-3-319-40358-8_15
465
466
15
Capacity Control, Modeling of Pile Head Stiffness …
For a single pile, the consideration of bending moments and deflections often governs design, because the ultimate load-carrying capacity of the soil is reached only at very large deflections. For pile groups such as the one typically used for offshore jacket structures, axial pile–soil interaction forces are in many cases the governing forces in designs. When sizing a pile foundation, the following items should be determined based on the basic capacity control requirements above: diameter, pile wall thickness, penetration (to provide adequate capacity due to soil–pile interaction), type of pile tips, pile spacing in a pile group, number of piles, geometry, location, mudline restraint, material strength, installation method, and other parameters as may be considered appropr
Data Loading...
