Underpinning Pile Assembly Alignment and Corrosion Protection
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Solution Overview
Problem
Existing underpinning pile assemblies face challenges such as misalignment of steel and concrete segments, inadequate depth inspection, instability in expansive soils, and corrosion of steel components due to exposure to moisture and oxygen, particularly in hard or dense earth formations.
Innovation Solution
The proposed underpinning pile assembly consists of vertically aligned steel pipes with an interior passageway and concrete pile segments, where a cable extends through both, ensuring alignment and stability. A locking assembly with a collar and wedges secures the cable, allowing for easy depth verification and minimizing exposure to moisture, with upset ends for secure pipe engagement and water injection for soil clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If precast concrete segments are stacked vertically into the soil one at a time, then the pile can be installed with almost no clearance beneath an existing structure, but the segments become misaligned and the pile becomes subject to separation at segment joints
Solution Approach 1:
The pile is divided into multiple precast concrete segments that can be installed sequentially with minimal clearance. Each segment is a separate unit that can be driven independently into the soil, allowing installation in tight spaces beneath existing structures while maintaining the ability to achieve proper alignment through the installation process
Solution Approach 2:
The first pile segment is driven into the soil to a predetermined depth before subsequent segments are installed. This preliminary positioning establishes the initial alignment reference that guides the installation of remaining segments, ensuring proper vertical alignment is achieved from the start of the stacking process
2Ease of operation
If precast concrete segments are stacked vertically into the soil one at a time, then the pile can be installed with almost no clearance beneath an existing structure, but independent inspection of pile depth becomes difficult without full-time inspection personnel
Solution Approach 1:
The pile assembly includes built-in alignment and positioning features that automatically indicate when segments are properly installed at the correct depth. The system self-verifies installation quality through its mechanical design, eliminating the need for continuous external inspection personnel while ensuring precise depth measurement
3Ease of operation
If an unreinforced stack of precast concrete segments is used, then the pile can be installed with almost no clearance beneath an existing structure, but the pile is subject to permanent separation at segment joints or breakage at segment midpoints in clay soils with high shrink-swell potentials
Solution Approach 1:
The pile combines precast concrete segments with reinforcement elements to create a composite structure. This composite design provides the necessary strength and continuity to resist separation at joints and breakage in expansive clay soils, while maintaining the minimal clearance installation advantage of segmented piles
4Ease of operation
If steel components are exposed to moisture and oxygen in the underpinning pile assembly, then the structure can be supported upon the earth, but the steel components suffer from corrosion
Solution Approach 1:
The steel components are protected from corrosive environments by creating a protective barrier or inert environment around them. This prevents direct exposure to moisture and oxygen, eliminating the corrosion mechanism while allowing the steel to perform its structural support function in the underpinning pile assembly
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures accurate alignment and stability of the pile assembly, facilitates easy installation across various soil types, including limestone, and reduces the risk of corrosion by minimizing exposure to moisture, while allowing for efficient depth verification and adaptation to different soil conditions.
Implementation Method 1
a cable extending through the interior passageway of the steel pipe and through the interior passageway of the concrete pile segment
Implementation Method 2
water may be injected through the steel pipe to clear soil from the interior passageway
Implementation Method 3
A locking assembly may be connected to the cable and affixed within one of the plurality of steel pipes
Data Source
AI summary
An underpinning pile assembly for supporting a structure upon the earth has at least one steel pipe with an interior passageway, a concrete pile segment positioned above the steel pipe, and a cable extending through an interior passageway of the steel pipe and through the interior passageway of the concrete pile segment. A locking assembly is connected to the cable and affixed within the steel pipe. This locking assembly includes a collar having an outer surface affixed to an interior wall of the lowermost pipe. The cable is affixed within an interior of the collar. A pair of wedges secure the cable within the interior of the collar.