Hydraulic Load Cell for Drilled Shaft Capacity Testing
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Solution Overview
Problem
Current methods for testing the load bearing capacity of drilled shafts and piles often result in conservative load assignments due to uncertainties, leading to overdesign and increased construction time, effort, and expense, with existing testing methods compromising the integrity of the shaft and being wasteful in terms of materials and time.
Innovation Solution
A load cell apparatus that creates a void in the structure, filled with pressurized fluid, allowing for accurate load testing without compromising the structure's integrity, using a self-sealing fluid to maintain the void and enable the structure to be used as a foundation support after testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional testing methods are used to determine load bearing capacity, then safety is improved by accounting for uncertainties, but overdesign occurs leading to increased construction time, effort, and expense
Solution Approach 1:
The patent replaces conventional mechanical testing methods that compromise shaft integrity with a fluid pressure-based testing system. A fluid is injected into the borehole to apply controlled pressure and measure load bearing capacity without physical damage, enabling accurate measurement while maintaining shaft usability.
Solution Approach 2:
The invention uses hydraulic principles by injecting fluid into the borehole to apply pressure and measure the load bearing capacity of the shaft. The fluid pressure systematically loads the shaft walls and bottom, allowing measurement of end-bearing and skin friction capacities without mechanical contact that would damage the structure.
2Measurement precision
If conventional testing methods are used, then load bearing capacity can be measured, but the integrity of the shaft is compromised and materials are wasted
Solution Approach 1:
The patent replaces destructive mechanical testing with non-contact fluid pressure application. The fluid systematically pressurizes the borehole to measure load capacity without physical contact that would compromise shaft integrity, allowing the same shaft to be used as a production pile after testing.
Solution Approach 2:
The invention introduces fluid as an intermediary medium between the testing apparatus and the shaft. The fluid transfers load to the shaft walls and bottom through pressure, enabling measurement without direct mechanical contact that would damage the shaft structure.
3Reliability
If safety factors are applied to account for uncertainties in end bearing and skin friction, then reliability is improved, but the load capacity assignment becomes overly conservative
Solution Approach 1:
The system uses feedback by continuously monitoring fluid pressure and volume injection to determine when the shaft reaches its load bearing capacity. The pressure required to fracture the shaft or cause failure provides direct feedback on the actual end-bearing and skin friction capacities, eliminating the need for conservative safety factors.
Solution Approach 2:
The patent replaces empirical safety factor calculations with direct mechanical measurement through fluid pressure testing. The actual load capacity is measured by the pressure required to cause controlled failure, providing precise data that eliminates the need for conservative estimates.
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
Enables accurate prediction of load bearing capacity, reducing the need for overdesign and conservativism, allowing structures to be used as production piles with a lower factor of safety, while minimizing material waste and construction time.
Implementation Method 1
when pressurized fluid is injected between the first portion and the second portion so as to cause the first portion and the second portion to move away from each other a sufficient distance
Implementation Method 2
a load is transferred to the first section of the structure and the second section of the structure by the pressure of the fluid on the first portion and the second portion, respectively
Implementation Method 3
In an embodiment, the created void is filled with a self-sealing fluid
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
In an embodiment, a hydraulic jack is provided having a first portion and a second portion. The first portion attached to a first section of a structure and the second portion attached to a second section of the structure. When a pressurized fluid is forced between the first portion and the second portion, a load is transferred to the first section and the second section by the pressure of the fluid on the first portion and the second portion. The first section and the second section are forced apart by the load, thus creating or enlarging at least one void in the structure. The pressurized fluid fills or partially fills one or more of the at least one void, thereby increasing the surface area effectively normal to the direction of the load in contact with the pressurized fluid.