Pore Pressure Sensor with Passive Gas Degassing Filter
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Solution Overview
Problem
Pore pressure monitoring devices, such as piezometers and tensiometers, experience significant deviations in measurements over time due to the accumulation of groundwater-borne gases forming bubbles, leading to pressure build-ups and errors in pressure transducers, which compromises the reliability of geotechnical risk management and incurs high maintenance and replacement costs.
Innovation Solution
Incorporating a degassing means with a gas-water filter and gas discharge system that allows gases to escape from the sensor cavity to the atmosphere, maintaining a partial gas pressure gradient and preventing gas bubble formation, thereby stabilizing measurement data without active management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If pore pressure monitoring devices are deployed underground for long-term monitoring, then measurement duration is extended, but measurement reliability deteriorates due to gas accumulation and bubble formation
Solution Approach 1:
The patent extracts and removes accumulated gases from the sensor cavity through a dedicated degassing system comprising a gas discharge means and gas-water filter. This prevents gas bubbles from forming and compromising the pressure transmission, thereby maintaining measurement reliability over extended periods without requiring device replacement
Solution Approach 2:
The patent introduces a gas-water filter as an intermediary component that selectively allows gases to pass through while blocking water. This mediator enables continuous operation by facilitating gas removal without disrupting the water-filled pressure transmission path, resolving the contradiction between long-term deployment and measurement reliability
2Reliability
If intensive maintenance and yearly replacement of pore pressure monitoring devices is performed, then measurement reliability is maintained, but maintenance costs and operational complexity increase
Solution Approach 1:
The patent implements a self-service degassing system that automatically removes accumulated gases from the sensor cavity without requiring external intervention or maintenance. The passive degassing design with gas discharge means and gas-water filter continuously maintains measurement reliability while eliminating the need for intensive maintenance and yearly device replacement
3Reliability
If a degassing system with gas discharge means is added to the sensor cavity, then gas accumulation is prevented, but device complexity increases
Solution Approach 1:
The patent employs a gas-water filter utilizing porous material properties to selectively separate gases from water based on pore size and surface tension characteristics. This passive separation mechanism prevents gas bubble formation in the pressure transmission path without requiring complex active degassing systems, thereby maintaining measurement stability while minimizing structural complexity
Solution Approach 2:
The patent converts the harmful effect of gas accumulation into a beneficial self-degassing mechanism. By allowing gases to naturally accumulate and then be passively discharged through the gas-water filter and discharge means, the system transforms the problem of gas interference into an automatic gas removal process that maintains measurement reliability without adding complex active control systems
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
The degassing system eliminates measurement deviations, ensuring long-term stability of sensor readings without the need for intensive maintenance, reducing costs and liabilities by preventing gas accumulation and bubble formation within the sensor cavity and ground filter pores.
Implementation Method 1
a gas-water filter means (12) providing a route for gas (8) to escape from the fluid in the sensor cavity towards the gas discharge means
Implementation Method 2
a gas-water filter means (12) providing a route for gas (8) to escape from the fluid in the sensor cavity
Implementation Method 3
The transducers and pressure gauges respectively are i.a. provided as vibrating-wire, pneumatic, or strain-gauge in operation, converting pressure into an electric signal
Implementation Method 4
the housing (26) may be provided at least partially fluid permeable, and especially comprising a pressure equalisation route, so as to allow equalisation of outside and inside pressure
Data Source
Figure 1a~1b
Figure 2~3
Figure 4~5
AI summary
The invention relates to a pore pressure monitoring device, for use in geotechnical engineering, adapted to be deployed underground for monitoring pore-water pressure in the ground, comprising a pressure sensor cavity (2) and a pressure sensor means (4), for sensing a fluid (6) pressure of a fluid in the sensor cavity (2), further comprising a degassing means (10), comprising a gas discharge means (14) and a gas-water filter means (12), wherein the gas-water filter means (12) is adapted for providing a route for gas (8) to escape from the fluid (6) in the sensor cavity (2), towards the gas discharge means (14) for discharging the filtered gas (8) to the atmosphere. The invention also relates to a method for monitoring pore-water pressure.