Prefabricated, modular hydropower foundation system for soil conditions
a hydropower foundation system and modular technology, applied in the field of modular hydropower systems, can solve the problems of long construction duration, high impact and cost, labor-intensive and time-consuming placement and compaction operations of earthfill materials, etc., and achieve the effect of increasing the section modulus of the beam base slab and maximizing the tension capacity
Pending Publication Date: 2022-10-13
LITTORAL POWER SYST INC
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Benefits of technology
The patent describes a beam base slab that includes two rows of beams arranged at a right angle to each other. The beams are tied together using post-tensioned tie rods, creating a single action between the two rows. This increases the section modulus of the beam base slab. The beams can also contain embedded hollow structural section (HSS) members to increase tension capacity at the top and bottom chords of the beams. The technical effect of this design is a stronger and more stable beam base slab that can withstand higher levels of tension.
Problems solved by technology
While the design and construction of earthen embankments is well understood and proven as a viable approach, there are many drawbacks with respect to environmental impacts and constructability.
These include 1) a large physical footprint for the actual structure; 2) excavation of appropriate borrow to construct the embankment; 3) substantial cofferdams / water control (including foundation dewatering) to allow for embankment construction “in the dry”; 4) excavation of “unsuitable” soils below the embankment to control long-term settlement; 5) labor intensive and time consuming placement and compaction operations for earthfill materials; and 6) limitations on conditions under which earthfill materials can be placed (i.e. not during freezing or overly wet conditions.)
Thus, potential hydropower sites with soil foundations often result in the contemplation of large earthen embankments with the attendant high levels of impacts and cost and long construction durations.
By contrast, low-head modular hydropower systems offer the potential for small footprints, reduced costs, and quick construction.
However, there are a number of potential difficulties with placing modular systems on soil foundations, particularly if one goal is to reduce or eliminate excavation and the use of cast-in-place concrete.
Modular systems that incorporate post-tensioning anchors cannot tolerate overall settlement that results in a loss of strain in the anchors.
Finally, some modular systems simply rely on a mechanical shear connection to a bedrock foundation for structural stability against sliding, making such systems inherently incompatible with soil foundation sites.
However, the one aspect of any hydropower project that is never generic and cannot be controlled is the foundation.
Current modular designs typically are suitable for bedrock foundations, but struggle with soils, particularly soils that are relatively loose or compressible.
Method used
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[0034]To demonstrate the structural capacity of the system of the present invention to support a modular hydropower installation, a pipe pile foundation has been sized based on a three-high stack of a low-head modular hydropower system (Littoral Power Systems, Inc., New Bedford, Mass., hereinafter “LPS”), which is judged to be representative of such modular systems. Pile design was conducted as per the procedure described in the US Navy NAVFAC Design Manual 7.02 (Foundations and Earth Structures), with the calculations as summarized below:
[0035]Using an LPS modular hydropower system as an example of a typical modular dam system leads to the assumption of a total load of 1,000 kips uniformly distributed over a foundation pad of 35 feet in length and 8 feet in width, maximum vertical soil pressure was determined to be approximately 4 kips per square feet (ksf) without deep foundation. Required ultimate pile capacity was thus determined to be approximately 200 kips (or 100 tons) per pi...
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A foundation system for modular hydropower systems and methods for constructing same. The foundation system is compatible with soils, particularly soils that are relatively loose or compressible, and thereby advantageous for the widespread implementation of low head modular hydropower systems. The foundation system includes pipe piles; sheet piles configured to be arranged transverse to the pipe piles; pile caps configured to be seated on top of the plurality of pipe piles; and a beam base slab configured to be securely positioned on top of the pile caps. A kit for the foundation system is also disclosed.
Description
CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 143,328, filed Jan. 29, 2021, the disclosure of which is incorporated by reference as if fully set forth herein in its entirety.FIELD OF THE INVENTION[0002]Embodiments of the present invention relate to modular hydropower systems, and more particularly, to foundation systems for modular hydropower systems.BACKGROUND OF THE INVENTION[0003]Traditional dam engineering practice for sites where surficial geology is composed of soils often results in the design of an earthen embankment as the water retaining structure. Concrete structures can be constructed on soil, but typically only on a narrow range of dense, suitable material. Earthen dams are more common because an earthfill embankment with upstream and downstream faces often sloped at 3:1 horizontal to vertical has a very wide base. This wide base broadly distributes the load of the structure and...
Claims
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Login to View More IPC IPC(8): E02D5/52E02D27/14
CPCE02D5/523E02D27/14E02D2300/0029E02D2300/002
InventorCOX, CHADWANG, BINDUQUETTE, DAVIDMATATHIA, ALEX
OwnerLITTORAL POWER SYST INC