Device and method for in situ penetration measurement of gas transport parameters in unsaturated soil layer

Patent metadata

Field	Value
Publication number	US-12007318-B2
Application number	US-202017639909-A
Country	US
Kind code	B2
Filing date	Jun 19, 2020
Priority date	Sep 3, 2019
Publication date	Jun 11, 2024
Grant date	Jun 11, 2024

Abstract

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.

First claim

What is claimed is:

1. A device for in situ penetration measurement of gas transport parameters in an unsaturated soil layer, comprising:
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, wherein a top portion of the porous gas-permeable tube is connected to a bottom portion of the sleeve through a thread, a bottom portion of the porous gas-permeable tube is connected to the conical penetration head through a thread, an inner portion of the porous gas-permeable tube is filled with sand grains, the gas supply system comprises a high-purity inert gas cylinder, a high-pressure air cylinder, a small-flow pressure regulating valve, a large-flow pressure regulating valve, a small-scale air gauge, a large-scale air gauge, a small-scale mass flow controller, a large-scale mass flow controller, and a gas pipeline, an output end of the high-purity inert gas cylinder is connected to one end of the gas pipeline through the small-flow pressure regulating valve, the small-scale air gauge, and the small-scale mass flow controller in sequence, an output end of the high-pressure air cylinder is also connected to one end of the gas pipeline through the large-flow pressure regulating valve, the large-scale air gauge, the large-scale mass flow controller in sequence, another end of the gas pipeline extends into and penetrates the sleeve and communicates with the porous gas-permeable tube at a bottom portion of the sleeve; the gas concentration sensor and the gas pressure sensor are installed in the inner portion of the porous gas-permeable tube, and the gas concentration sensor and the gas pressure sensor are respectively connected to the gas concentration display recorder outside the porous gas-permeable tube and the gas pressure display recorder through data lines thereof.

2. The device for in situ penetration measurement of gas transport parameters in the unsaturated soil layer according to claim 1 , wherein a rigid body formed by the sleeve, the porous gas-permeable tube, and the conical penetration head is inserted into the unsaturated soil layer, and the porous gas-permeable tube is located at a depth in the unsaturated soil layer where the gas transport parameters are required to be measured.

3. A testing method for in situ penetration measurement of gas transport parameters in an unsaturated soil layer applied in the device according to claim 2 , comprising:
step one: installing the gas concentration sensor and the gas pressure sensor on the inner wall of the porous gas-permeable tube, connecting, by the data lines, the gas concentration sensor and the gas pressure sensor to the gas concentration display recorder and the gas pressure display recorder, connecting the sleeve, the porous gas-permeable tube, and the conical penetration head in sequence to form a rigid body, filling the porous gas-permeable tube with sand grains;
step two: inserting the porous gas-permeable tube to a depth of the unsaturated soil layer required to be tested;
step three: connecting, through the gas pipeline, the high-purity inert gas cylinder, the high-pressure air cylinder, the small-flow pressure regulating valve, the large-flow pressure regulating valve, the small-scale air gauge, the large-scale air gauge, the small-scale mass flow controller, and the large-scale mass flow controller to form the gas supply system, wherein an outlet end of the gas supply system is connected to a top end of the sleeve;
step four: turning on the small-flow pressure regulating valve, turning off the large-flow pressure regulating valve, delivering, through the gas supply system, inert gas to the porous gas-permeable tube, turning on the gas concentration display recorder and the gas pressure display recorder, measuring a concentration value and an air pressure value of the inert gas in the porous gas-permeable tube in real time, and regulating, through the small-scale mass flow controller, an air intake flow to a constant flow value, such that after a gas concentration measured by the gas concentration sensor is stable, a gas pressure value measured by the gas pressure sensor is equal to an atmospheric pressure value;
step five: recording an inert gas concentration value C 1 measure at this timed by the gas concentration sensor in the porous gas-permeable tube and a corresponding first air intake flow value q v1 of the small-scale mass flow controller after reading of the gas concentration display recorder is stable;
step six: turning off the small-flow pressure regulating valve, turning on the large-flow pressure regulating valve, delivering, through the gas supply system, air to the porous gas-permeable tube, increasing, through the large-scale mass flow controller, the air intake flow to a higher constant flow value, such that the gas pressure value measured by the gas pressure sensor is greater than the atmospheric pressure value and exhibits a significant difference, and recording a gas pressure value P 2 measured at this time by the gas pressure sensor in the porous gas-permeable tube and a corresponding second air intake flow value q v2 of the large-scale mass flow controller after reading of the gas pressure display recorder is stable;
step seven: substituting the measured inert gas concentration value C 1 and the first air intake flow value q v1 into a following formula to obtain a gas diffusion coefficient value D:

D
=

P
s

⁢

T

a
⁢
t
⁢
m

P

a
⁢
t
⁢
m

⁢

T
s

⁢

q

v
⁢
1

4
⁢
π
⁢

r
0

(

C
1

-

C
environment

)

wherein D is a gas diffusion coefficient of the unsaturated soil layer, C 1 is the concentration value of the inert gas in the porous gas-permeable tube when gas is stably transported, C enviroment is a background concentration value of the inert gas in the soil layer, r 0 is a radius of the porous gas-permeable tube, P s and T s respectively are an atmospheric pressure and a temperature under a standard condition, and P atm and T atm respectively are

Assignees

• Univ Zhejiang

Inventors

• Zhan Liangtong
• Wu Tao
• Feng Song
• Chen Yunmin

Classifications

• G01N15/0826 Primary

  and measuring fluid flow rate, i.e. permeation rate or pressure change · CPC title

• G01N2013/003

  Diffusion; diffusivity between liquids · CPC title

• G01N33/24

  Earth materials (G01N33/42 takes precedence) · CPC title

• G01N13/04 Primary

  Investigating osmotic effects · CPC title

• G01N13/00

  Investigating surface or boundary effects, e.g. wetting power; Investigating diffusion effects; Analysing materials by determining surface, boundary, or diffusion effects (scanning-probe techniques or apparatus G01Q) · CPC title