Aggregate Column Modulus Testing via Laser Deflection Sensing
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Solution Overview
Problem
Existing methods for constructing short aggregate columns fail to effectively measure the modulus of each lift during construction, leading to inefficiencies and increased costs due to the inability to account for dynamic movements during tamping, which affects the load-bearing capacity and compliance with design standards.
Innovation Solution
A novel apparatus and method that measures the deflection of each lift in real time using a sensing system and filtering algorithm to account for vibrations from the hammer, allowing for continuous monitoring of stiffness and ensuring each lift meets the target modulus before adding a new layer, thereby optimizing compaction energy and verifying compliance with design criteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If real-time measurement of deflection during tamping is implemented, then manufacturing precision and reliability are improved, but device complexity increases due to the need for sensing systems and filtering algorithms
Solution Approach 1:
The patent replaces traditional mechanical measurement systems with an optical sensing system that uses lasers and angle measurements to detect deflection during tamping. This substitution enables real-time modulus measurement without complex mechanical contact sensors, resolving the contradiction by achieving high measurement precision through non-mechanical means.
Solution Approach 2:
The patent introduces angle sensors as intermediary devices that measure the angle between the tamper and vertical axis, which then serves as a proxy for calculating deflection and modulus. This intermediary measurement approach simplifies the direct measurement challenge while maintaining precision, as angle measurements are easier to obtain accurately than direct deflection measurements during dynamic tamping.
2Productivity
If real-time monitoring of each lift is implemented, then productivity is improved by preventing rework, but loss of time increases due to additional measurement and filtering processing
Solution Approach 1:
The patent applies filtering algorithms to remove vibration effects from angle measurements in real-time during the tamping process. By preprocessing the measurement data to eliminate noise sources, the system maintains measurement accuracy without requiring additional measurement time, thus resolving the contradiction between productivity improvement and time loss.
Solution Approach 2:
The patent implements real-time feedback by continuously monitoring the calculated modulus during each lift and comparing it against target values. This immediate feedback allows operators to adjust tamping parameters on-the-spot, preventing rework and improving overall productivity despite the additional measurement processing required.
3Measurement precision
If vibration effects are filtered from angle measurements, then measurement precision is improved, but device complexity increases due to the filtering algorithm
Solution Approach 1:
The patent replaces complex mechanical vibration isolation systems with computational filtering of angle measurement data. By using software-based filtering algorithms to remove vibration effects from the measurements, the system achieves high measurement precision without the mechanical complexity of physical vibration damping mechanisms.
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 enables real-time verification of each lift's stiffness during construction, reducing the need for rework, ensuring columns are built to capacity, and lowering construction costs by preventing unnecessary compaction energy expenditure.
Implementation Method 1
A sensing system measures angles of various parts of a compacting machine to determine if a threshold value is reached
Implementation Method 2
A filtering algorithm is applied to the angle measurements to account for vibration resulting from operation of a hammer of the compacting machine
Implementation Method 3
deflection at the top of the column is measured in real time to ensure each lift meets a target modulus
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A system and method of determining lift deflection during construction of aggregate columns allows for real time monitoring of construction to ensure meeting defined parameters. The amount of deflection of a tamper head during tamping is determined multiple times for each lift. When the amount of deflection matches a predetermined value, tamping is stopped.