Ring Load Cell for Pile Testing Without Structural Damage
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Solution Overview
Problem
Current methods for testing the load-bearing capacity of drilled shafts often interfere with the structural integrity of the piles, leading to wasteful abandonment of tested shafts and the use of overly conservative safety factors, resulting in unnecessary construction of larger and deeper foundations.
Innovation Solution
The implementation of a ring or annular load cell that can be placed in production piles, allowing concrete and grout to pass through during casting, and remaining in place after testing, reducing interference and enabling a higher confidence in load-bearing capacity assessment with a lower factor of safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional testing methods are used to determine load-bearing capacity, then measurement precision is improved, but the tested piles suffer structural damage and must be abandoned
Solution Approach 1:
The patent introduces a separate reaction pile as an intermediary element that provides the necessary reaction force for load testing. This allows the test load to be applied to the production pile without requiring the production pile itself to provide the reaction force, thereby preventing structural damage to the tested pile while still enabling accurate load-bearing capacity measurement.
Solution Approach 2:
The patent uses a reaction pile that is a copy or duplicate of the production pile configuration. This reaction pile serves as a surrogate to absorb the test loads and provide the necessary reaction force, allowing the production pile to be tested without suffering permanent damage. The reaction pile effectively copies the structural characteristics needed for testing while being dedicated solely to that purpose.
2Reliability
If safety factors are increased to account for uncertainty in load-bearing capacity, then reliability is improved, but construction costs and foundation dimensions increase
Solution Approach 1:
The patent implements a feedback mechanism by conducting actual load tests on production piles to obtain precise load-bearing capacity data. This empirical feedback replaces the need for conservative estimated safety factors, allowing engineers to design foundations with accuracy-based safety margins rather than overly conservative defaults, thereby reducing unnecessary material and construction effort.
Solution Approach 2:
The patent replaces the mechanical system of conservative safety factor calculations with an empirical measurement system. Instead of relying on theoretical estimates and large safety factors, the system uses actual load testing to determine precise capacity, substituting mechanical overdesign with measured performance data.
3Measurement precision
If tested piles are abandoned after testing, then measurement precision is improved, but productivity decreases due to unnecessary construction
Solution Approach 1:
The patent uses a reaction pile as an intermediary that absorbs the test loads and protects the production pile from damage. This allows the production pile to survive the testing process intact, enabling it to be reused as a load-bearing element in the final structure, thereby eliminating the waste associated with abandoning tested piles.
Solution Approach 2:
The patent implements a system where the reaction pile is the element that is discarded after testing, while the production pile is recovered and reused. This reverses the conventional approach by sacrificing the reaction pile (which was never intended for load-bearing service) and preserving the production pile for its intended purpose, thereby improving construction productivity.
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 approach allows for a more accurate assessment of load-bearing capacity with reduced interference, enabling the use of tested piles as production piles, thereby optimizing construction efficiency and reducing costs by allowing a higher percentage of piles to be used without compromising structural integrity.
Implementation Method 1
a ring load cell positioned within the borehole and adapted to measure a capacity of the shaft to support a test load
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
An annular assembly, or ring cell, is provided for testing the load bearing capacity of piles. The ring cell walls of the annular assembly can be made of stamped material. The ring cell walls can be an outer ring wall and an inner ring wall. Alternately, the ring cell walls can have a "U"-type shape cross-section including an outer ring wall, an inner ring wall, and a top wall. Fluid can be provided to the annular assembly through fluid supply lines into an expansion zone. The expansion zone can be a space having a bladder for filling with fluid. In another embodiment, the expansion zone can be a space between a filler material capable of withstanding high pressure separated with a membrane. The pressure of the fluid in the expansion zone can be monitored during testing.