In Situ Soil Gas Transport Measurement Device
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Solution Overview
Problem
Current methods for measuring the gas diffusion coefficient and permeability coefficient of unsaturated soil layers are time-consuming, laborious, and prone to interference, especially when dealing with large-scale soil covers like landfill sites, due to spatial variability and the need for extensive sampling and complex laboratory analysis.
Innovation Solution
A device and method for in situ measurement using a gas supply system, gas concentration and pressure sensors, and a porous gas-permeable tube with a conical penetration head, allowing for direct measurement of gas transport parameters at specific depths within the soil layer, reducing the need for sample transportation and complex laboratory testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If soil samples are collected and transported to the laboratory for testing, then gas diffusion coefficient and permeability coefficient can be measured, but the process is time-consuming, laborious, and samples are easily disturbed during transportation
Solution Approach 1:
The device enables the soil layer to test itself in situ. The porous gas-permeable tube with conical penetration head is directly inserted into the soil layer to measure gas transport parameters at the measurement point, eliminating the need for sample collection and transportation. The system performs self-testing by injecting gas through the porous tube and measuring concentration and pressure changes directly at the measurement location.
2Measurement precision
If soil samples are collected from large-scale soil covers, then gas transport parameters can be tested, but the number of samples required is huge due to spatial variability
Solution Approach 1:
The device divides the measurement process into discrete depth levels. The porous gas-permeable tube can be inserted to different depths to measure gas transport parameters at multiple levels independently. This segmentation allows targeted measurement at specific depths without requiring extensive sampling across the entire soil cover volume, improving testing efficiency while accounting for spatial variability.
3Loss of time
If in situ testing methods are used, then testing time and sample disturbance are reduced, but some methods require high testing costs or complex numerical analysis
Solution Approach 1:
The porous gas-permeable tube acts as an intermediary between the gas supply system and the soil layer. It enables gas injection and concentration measurement directly in the soil without requiring complex numerical analysis or empirical coefficients. The tube's porous structure allows controlled gas release into the soil, and the integrated concentration sensor measures the resulting concentration changes, providing direct physical measurement that simplifies the testing system.
4Measurement precision
If laboratory testing is performed on collected samples, then gas diffusion and permeability coefficients can be determined, but sample disturbance during transportation affects measurement accuracy
Solution Approach 1:
The device performs preliminary measurement action directly at the measurement location before any sample disturbance can occur. By inserting the porous gas-permeable tube with integrated sensors directly into the soil layer in situ, the system measures gas transport parameters at the exact location and depth required, eliminating subsequent sample handling and transportation that would compromise sample integrity and measurement reliability.
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 quick and accurate measurement of gas diffusion and permeability coefficients at specific points in the soil, avoiding errors from sample disturbance and reducing costs by allowing on-site testing, thus improving engineering design and air-sealing performance of landfill soil covers.
Implementation Method 1
a porous gas-permeable tube, and a conical penetration head. A top portion of the porous gas-permeable tube is connected to a bottom portion of the sleeve through threads
Implementation Method 2
The gas diffusion coefficient and permeability coefficient are important indicators for determining the transport of gas in the soil layer
Implementation Method 3
test the gas diffusion coefficient and permeability coefficient of the samples according to Fick's law and Darcy's law, respectively
Data Source
AI summary
A device and a method for in situ penetration measurement of gas transport parameters in an unsaturated soil layer. The device mainly consists of a gas supply system, a gas concentration display recorder, a gas pressure display recorder, a sleeve, a gas concentration sensor, a gas pressure sensor, a porous gas-permeable tube and a conical penetration head. The gas diffusion coefficient and permeability coefficient of the unsaturated soil can be obtained by only measuring the gas pressure value, the gas concentration value and the corresponding gas flow value of an unsaturated soil layer at a depth required to be tested, and substituting same into calculation formulae of the gas diffusion coefficient and permeability coefficient. The testing process of the method is simple and fast, and is low in cost, simple in operation and convenient in calculation.