Pile foundations for supporting power transmission towers
Pile foundations for power transmission towers or the like for installation in different types of soil prone to frost heaving include a casing pipe and a dipped pile, comprising a shaft and a toe bulb, secured at the bottom of the shaft. The pile comprises rigid elements that are mounted on the shaft in the direction of horizontal forces acting on the pile against the anticipated horizontal loads. The rigid elements transfer horizontal forces from the pile to the casing pipe.
1. A pile foundation for supporting horizontal and vertical loads in substrates susceptible to frost heaving, the pile foundation comprising:
a casing pipe;
an immersed pile comprising a shaft and a toe bulb secured at the bottom of the shaft, positioned in the casing pipe; and
rigid elements each comprising a generally flat plate directly mounted on the shaft transverse to horizontal forces from transmission lines acting on the pile and configured for transferring the horizontal forces from the pile to the casing pipe, the rigid elements arranged in pairs wherein the rigid elements are fixed on opposite sides of the shaft from one another and in a common plane transverse to the horizontal forces from the transmission lines.
2. The pile foundation of claim 1 , wherein each of the rigid elements is disposed on the shaft and spaced apart by not less than the length of each of the rigid elements.
3. The pile foundation of claim 1 , further comprising a cutoff screen mounted on the shaft from an upper part of the shaft to a level of seasonal freezing and thawing of soils.
4. The pile foundation of claim 3 , wherein the cutoff screen comprises a plastic film or sheet.
5. The pile foundation of claim 3 , wherein the cutoff screen comprises a galvanized metal sheet.
6. The pile foundation of claim 3 , wherein the cutoff screen is fixed to the shaft using clamps.
7. The pile foundation of claim 1 , wherein each of the rigid elements has a shape selected from square, triangular, and circular.
8. The pile foundation of claim 1 , wherein the pile shaft is made of one of concrete, steel, or reinforced concrete.
9. The pile foundation of claim 1 , wherein the pile toe bulb has a shape selected from tapered, circular, and flat.
10. The pile foundation of claim 1 , wherein the toe bulb is secured by welding to the shaft.
11. The pile foundation of claim 1 , wherein the toe bulb is secured by being molded as a single monolithic structure with the shaft.
12. The pile foundation of claim 1 , wherein the casing is buried to a depth greater than a level of seasonal freezing and thawing of soils.
13. The pile foundation of claim 1 , wherein a space between the casing and the shaft is filled with an inert non-heaving material.
14. The pile foundation of claim 13 , wherein each of the rigid elements comprises a steel material.
15. The pile foundation of claim 13 , wherein each of the rigid elements is in the range of 1-50 cm long, 1-20 cm wide, and 0.1-5 cm thick.
16. The pile foundation of claim 13 , wherein each of the rigid elements is welded to the shaft.
17. The pile foundation of claim 13 , wherein the shaft comprises a steel material.
18. The pile foundation of claim 1 , wherein a space between the casing and the shaft is filled with one of concrete and mortar.
19. The pile foundation of claim 18 , wherein the space between the casing pipe and the shaft is filled with one of an M100-M350 grade mortar and a B10-B40 grade concrete.