Saturday, November 17, 2012

Steel piles: H-Piles, Pipe Piles.

These are generally H-piles and pipe piles. Pipe piles may be driven either “open-end” or “closed-end.” Steel  piles are vulnerable to corrosion, particularly in saltwater; however, experience indicates  they are not significantly  affected by corrosion in undisturbed soil. Schematics  of H-piles and pipe piles are presented in
Figure 1-3.

(a)  Steel H-piles.  This type can carry larger loads, both axially and in bending, than timber piles and can withstand rough handling.  H-piles can be driven into dense soil, coarse gravel,  and soft rock with minimum damage, and cause minimal  displacement of the surrounding soil while being driven.   Hardened and reinforced pile tips should be used where large boulders, dense gravel, or hard debris may damage the pile.  Splices are commonly made with full penetration butt welds or patented splicers (Figure 1-3a).  H-piles can bend during driving and drift from planned location.  Thus, H-piles may not be suitable when tolerance is small with respect to location and where absolute plumbness is required.  Table 1-3 lists commonly available H-piles together with properties and dimensions.

(b)  Steel pipe piles.  Commonly used steel pipe piles are listed in Appendix B together with properties and dimensions. Steel pipe piles are generally filled with concrete after driving to increase the structural capacity.  If the soil inside the pipe is removed during driving, open-end piles in cohesionless soil will  cause less soil displacement and compaction, and in cohesive soils will cause less heaving of adjacent ground and
nearby piles.  If the soil inside the pipe is not removed during driving, the pipe becomes plugged and acts as a closed-end displacement  pile.  Criteria are presently unavailable for computing the depth at which a driven, open-end pile will plug.

In cases where the foundation contains boulders, soft rock, or other obstructions, the open-end pile permits inspection after removal of the plug material and ensures that the load will be transferred directly to the load-bearing stratum.  Splices are commonly made by full penetration butt welds or fillet wells (Figure 1-3b) or patented splicers.

Figure 1-3.  Steel pile splices

Table 1-3
Standard H-piles; Dimensions and Properties (AISC 1969)

No comments:

Post a Comment