Offset Compressible System for Static Penetrometer Precision
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Solution Overview
Problem
Current penetrometer technologies face challenges in measuring soil compactness, particularly in high compactness soils, where static mode measurements are impractical due to high resistance, and dynamic mode measurements are less precise and discontinuous, failing to accurately distinguish tip resistance from lateral friction.
Innovation Solution
A penetrometer design featuring a central rod with a measuring tip, a surrounding hollow tube, and a compressible system with oil chambers and pistons, allowing for continuous static mode measurements with a pressure sensor and displacement sensor to accurately measure soil resistance, and optional vibro-dynamic assistance for overcoming high resistance layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If static mode measurement is used, then measurement precision is improved, but device complexity and required force increase due to high soil resistance
Solution Approach 1:
The device separates the measurement function (tip resistance) from the driving function (overcoming soil resistance and lateral friction) by using a hollow tube that can slide independently on the central rod. This allows the measuring tip to remain isolated from the forces applied to drive the device into the ground.
Solution Approach 2:
The measurement function is extracted from the driving system. The hollow tube containing the measuring tip can move independently relative to the central rod, allowing continuous static measurements to be taken while the driving system overcomes high soil resistance through dynamic means.
2Force
If dynamic mode measurement is used, then penetration capacity is improved, but measurement precision deteriorates due to discontinuous measurements and inability to separate tip resistance from lateral friction
Solution Approach 1:
The hollow tube can slide continuously along the central rod during dynamic penetration, enabling continuous static measurements of tip resistance even while the device is being driven into high resistance soils by dynamic means. This eliminates the discontinuous nature of traditional dynamic measurements.
Solution Approach 2:
The hollow tube acts as an intermediary between the driving system (central rod) and the measurement system (measuring tip). It transmits the driving force while allowing independent movement of the measuring tip, thereby separating the effects of lateral friction from tip resistance measurements.
3Measurement precision
If traditional static penetrometer is used, then measurement precision is improved, but it becomes impractical in high compactness soils due to excessive force requirements
Solution Approach 1:
The device combines dynamic driving capability with static measurement function. The hollow tube can slide dynamically along the central rod, allowing the device to be driven into high compactness soils using dynamic forces while maintaining continuous static measurements throughout the penetration process.
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 precise and continuous measurement of soil compactness, effectively addressing the limitations of existing technologies by providing accurate resistance data without the need for excessive force or complex equipment, and allowing for the evaluation of soil liquefiability and elastoplastic properties.
Implementation Method 1
A first oil chamber (61) formed in the measuring cell (3), and a first piston (62) integral with a second end (12) of the central rod (1) and able to slide in the first chamber
Implementation Method 2
a second oil chamber (64) in fluid communication with the first chamber (61), a second piston (65) capable of sliding in the second chamber (64)
Implementation Method 3
a calibrated compressible device (66) in contact with the second plunger (65)
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a penetrometer (100) comprising: • At least one central rod (1) terminating at one end in a measuring tip (11); • At least one hollow tube (2) surrounding the central rod (1), the latter being able to slide inside the hollow tube (2); • A measuring cell (3) in contact with the hollow tube (2), intended to transmit a force applied by support means, so as to cause penetration into the ground of the hollow tube (2) and the central rod (1); The penetrometer (100) is remarkable in that it comprises a compressible system (6) ensuring an elastic connection between the measuring cell (3) and a second end (12) of the central rod (1), said compressible system (6) comprising at least one column (63) offset from the axis of the central rod (1).