Static Penetrometer With Vibration For Soil Liquefaction
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Solution Overview
Problem
Current methods for evaluating the liquefiable nature of soils are complex and rely on empirical correlations, often requiring invasive tests like piezocone tests or cyclic loading, which are not straightforward or simple to implement.
Innovation Solution
A static penetrometer with a central rod and surrounding hollow tube, equipped with an electric jack for controlled penetration and vibration at specific frequencies, allowing for direct measurement of soil resistance and liquefaction assessment through double measurement techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard penetration tests (SPT) or cone penetration tests (CPT) are used to evaluate liquefiable soils, then measurement data can be obtained, but the methods require complex empirical correlations and normalized variables for evaluation
Solution Approach 1:
The patent applies mechanical vibration at a determined frequency (1-5 Hz) to the central rod during penetration testing. This vibration directly affects the soil structure and allows for direct identification of liquefiable characteristics through changes in penetration resistance, eliminating the need for complex empirical correlations and normalized variable transformations required by conventional SPT and CPT methods.
2Reliability
If piezocone tests or cyclic loading tests are performed, then detailed soil characteristics can be obtained, but the implementation becomes complex and time-consuming
Solution Approach 1:
The patent performs preliminary vibration application during the penetration process itself, rather than requiring separate cyclic loading tests after penetration. The vibration is applied continuously or intermittently during the penetration test, allowing direct observation of soil liquefaction characteristics in real-time, thus eliminating the need for additional time-consuming cyclic loading tests in the laboratory.
3Measurement precision
If static penetration measurement is performed without vibration, then precise resistance measurement is achieved, but direct identification of liquefiable character is difficult
Solution Approach 1:
The patent combines precise static penetration resistance measurement with simultaneous mechanical vibration application. The vibration at determined frequency (1-5 Hz) directly excites the soil structure, causing liquefiable soils to exhibit distinct changes in penetration resistance. This allows direct detection and measurement of liquefiable character while maintaining the precision of static penetration measurement, without requiring complex empirical correlations.
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 a more direct and simpler evaluation of soil liquefiability by identifying layers with high risk of liquefaction through controlled penetration and vibration, providing critical data for foundation stability during earthquakes.
Implementation Method 1
configured to transmit a displacement to a second end of the central rod leading to a controlled driving of the measuring tip into the ground
Implementation Method 2
configured to be applied to the second end of the central rod vibration at a specific frequency
Implementation Method 3
the latter measures the tip resistance and optionally the lateral friction on a cylindrical sleeve located above the tip
Data Source
Figure 1
Figure 2
Figure 3a~4
AI summary
The invention relates to a penetrometer (100) for evaluating the liquefiable character of a soil, comprising: • at least one central rod (1) terminated at a first end by a measuring tip (11); • at least one hollow tube (2) surrounding the central rod (1), the latter being capable of sliding inside the hollow tube (2). The penetrometer (100) also comprises an electrical cylinder (6) comprising an external body (61) solidly attached to the hollow tube (2) and a movable body (1), said movable body (1) being: • configured to transmit a movement to a second end (12) of the central rod (1) leading to a controlled pressing of the measuring tip (11) into the soil, and to measure a force applied to produce said movement, • and suitable for applying a vibration at a determined frequency to the second end (12) of the central rod (1).