JP4236366B2 - Exploration device and exploration method for underground gas - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and an exploration method for exploring gas generated in the ground.
[0002]
[Prior art]
When excavating the ground or excavating landfill waste, there are cases where it is difficult to ensure safe work due to generation of gas that is harmful to human body, gas that may ignite or explode.
In addition, when such a large amount of gas is generated, there is a possibility that an oxygen deficiency accident may occur due to a relative shortage of oxygen.
In order to prevent the occurrence of such accidents, conventionally the following gas exploration technology has been developed.
<A> A hollow rod-shaped gas sampling device with a sharp tip is inserted into the ground to a predetermined depth, volatile organic chlorine gas is taken into the sampling device, and the sample is pulled up to the ground. How to analyze. (For example, JP-A-11-173963)
<B> A method for calculating the total amount of methane gas contained in natural ground by drilling using mud and collecting methane gas contained in the circulating mud. (For example, JP-A-9-292318)
[0003]
[Problems to be solved by the invention]
The conventional underground gas exploration device and exploration method as described above have the following problems.
<B> The method using the gas sampler requires that the gas sampler be pulled up to the ground every time the measurement depth is reached. Therefore, as the investigation depth increases, the time required for raising and lowering the sampler increases, and as a result, the time required for sample collection increases.
Moreover, the penetration hole is opened during the removal of the gas collector, and there is a possibility that a light gas such as methane may leak from the hole, which is dangerous.
<B> Gas sampling methods by boring excavation include a method of circulating mud water, a method of performing anhydrous boring, and a method of sampling gas with a suction pump.
In either method, if the investigation depth is deep, it takes time to raise and lower the core tube, so that it takes time to collect the sample, which is uneconomical.
Further, since the excavation hole is opened during the addition of the boring rod, there is a possibility that a light gas such as methane may leak from the hole, which is dangerous.
<C> There are the following problems when collecting by boring for waste ground buried in a managed final disposal site.
(1) Since the waste ground has a larger porosity than the general ground, the amount of infiltrated muddy water is greatly increased when drilling, which is uneconomical. Even if a large amount of muddy water is used for boring excavation, an excessive burden is imposed on the leachate treatment facility at the disposal site.
{Circle around (2)} In the case of anhydrous boring, the time required for excavation increases compared to mud excavation.
(3) Further, the waste landfilled at the disposal site includes those with larger dimensions than natural ground materials. Therefore, when the tip of the boring rod comes into contact with the large waste, excavation work is performed. It becomes difficult.
[0004]
[Object of the present invention]
The present invention has been made to remedy the above-described problems, and provides an exploration apparatus and exploration method for underground generated gas that can perform expeditious exploration and prevent harmful gases from leaking to the ground during exploration. The purpose is to provide.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the underground gas exploration device of the present invention comprises an exploration rod and a press-fitting device that pressurizes the base side of the exploration rod and press-fits the tip into the ground. The rod is attached to the vicinity of the tip of the probe. The pressure sensor detects the atmospheric pressure outside the probe rod, and the gas is opened near the tip of the probe rod. Characterized by an exploration device for underground generated gas, which is composed of a suction port and a packer that is expandable to the outer periphery of the exploration rod and is attached to the base side of the exploration rod with respect to the pressure sensor and the gas suction port Is.
[0006]
Further, the underground gas exploration method of the present invention includes a pressure sensor that detects an external atmospheric pressure, a gas suction port that sucks and collects external gas, and is expandable to the outer periphery, and is a pressure sensor for the exploration rod. And a probe that is composed of a packer attached to the base side of the gas suction port and the probe rod, pressurize the base of the probe rod, press the tip into the ground, and then place the probe rod from the ground for a certain distance. Pull out to form a cavity at the tip, expand the packer to close the space between the exploration rod and the hole wall, measure the amount of spillage by detecting the pressure of gas collected in the tip cavity, and simultaneously generate It is characterized by an underground gas exploration method that collects gas.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
[0008]
<I> Exploration rod.
The exploration device of the present invention is constituted by an exploration rod A and a press-fitting device B.
The exploration rod A is a hollow cylinder with a sharp tip, and includes a pressure sensor 1, a gas suction port 2, and a packer 3.
With the press-fitting device B, the base side of the exploration rod A is pressurized and the tip is press-fitted into the ground.
[0009]
<B> Pressure sensor 1.
A pressure sensor 1 is attached to the exploration rod A near its tip. The pressure sensor 1 is attached to the outside and can detect the atmospheric pressure outside the exploration rod A.
The detection part of the pressure sensor 1 is protected by a filter 11 so that ground material and waste do not flow from the outside.
The numerical value detected by the pressure sensor 1 is transmitted to the measurement facility on the ground via the amplifier 12 via the measurement line.
[0010]
<C> Gas suction port 2.
In the vicinity of the tip of the exploration rod A, a gas suction port 2 is further opened to the outside.
A negative pressure can be applied to the gas suction port 2 through the gas sampling tube 21 to pump the gas outside the exploration rod A to the measuring device on the ground.
The suction port 2 is protected by a filter 22 such as porous metal so that ground material and waste do not flow from the outside.
[0011]
<D> Packer 3.
The exploration rod A is attached with a packer 3 that can expand to the outer periphery thereof.
The packer 3 is provided on the base side of the exploration rod A with respect to the pressure sensor 1 and the gas suction port 2.
In order to attach the packer 3, a groove is formed on the outer circumference of the exploration rod A in the circumferential direction.
The airbag 31 is accommodated in the groove so as to surround the outer periphery of the exploration rod A.
A split plate 32 is attached to the outer periphery of the airbag 31, and a tension spring 33 for pulling the split plate 32 toward the exploration rod A is provided.
The airbag 31 is inflated toward the outer periphery by supplying pressurized air from the ground, and presses the dividing plate 32 against the hole wall.
If the supply of pressurized air is stopped and negative pressure is applied as necessary, the dividing plate 32 is pulled by the elasticity of the tension spring to form the same curved surface as the outer peripheral surface of the exploration rod A to protect the outer periphery of the groove. .
[0012]
<E> Press-in of exploration rod A.
The base of the exploration rod A having the above configuration is pressed by the press-fitting device B and the tip is press-fitted into the ground to be inspected. As the press-fitting device B, a known device such as a stationary device or a vehicle-mounted device can be used.
During the press-fitting of the exploration rod A, the same curved surface as the outer peripheral surface of the exploration rod A is formed by sucking the air inside the airbag 31 so that the divided plate 32 around the packer 3 does not obstruct the press-fitting.
For this purpose, in the control circuit of the packer 3, the electromagnetic valve k1 on the suction circuit side that connects the airbag 31 and the suction pump is opened, and the electromagnetic valve k2 on the pressure circuit side that connects the airbag 31 and the compressor is closed.
[0013]
<F> Pull up exploration rod A.
When reaching a predetermined depth, the exploration rod A is pulled out from the ground by a certain distance to form a cavity at the tip. Then, surrounding gas gathers toward this cavity.
[0014]
<G> Expansion of the packer 3.
In this state, the electromagnetic valve k1 on the suction circuit side of the packer control circuit is closed, and the electromagnetic valve k2 on the pressure circuit side is opened. Then, the pressure air is supplied to the airbag 31 so that the packer 3 is inflated.
As a result, since the packer 3 closes between the exploration rod A and the hole wall, a certain force in the cavity increases. At that time, gas does not escape from the gap to the ground, and there is no danger.
[0015]
<H> Measurement of gas discharge amount.
The pressure sensor 1 measures the pressure p0 in the cavity in the initial state immediately before the packer 3 is operated.
After the operation of the packer 3, an increase in pressure accompanying gas generation is measured by the pressure sensor 1.
If the pressure measured after the elapse of the fixed time Δt is p, the gas amount Δv generated between Δt according to Boyle's law can be obtained by the following equation.
Δv = {(p / p0) −1} v
Here, Δv: the amount of gas generated during the time Δt.
p: Initial pressure in the cavity≈atmospheric pressure.
p0: Pressure inside the cavity after the time Δt has elapsed.
v: The volume of the cavity.
[0016]
<Li> Gas sampling.
By operating the suction pump of the gas measuring device, the gas in the cavity is sucked through the gas suction port 2 and sent into the cushion tank.
When groundwater is contained at this time, it is separated into liquid and gas in the cushion tank by a known separation device.
In this state, the suction pump is operated to pull the gas from the gas phase and send it to the gas sensor, and the type and concentration of the gas are measured, displayed, and recorded.
The suction amount of the suction pump at this time is preferably matched with the amount of gas discharged measured in the previous step.
[0017]
<Nu> Shrinkage of packer 3.
By closing the electromagnetic valve k2 of the pressurizing circuit and opening the electromagnetic valve k1 of the suction circuit, the packer 3 is contracted by sucking the air in the airbag 31.
As a result, the dividing plate 32 forms the same curved surface as the surface of the exploration rod A, and there is no resistance to press-fitting.
In this state, the exploration rod A is press-fitted to the next exploration depth, and the same process as described above is repeated. If the length of the probe rod A is insufficient, an extension rod is added.
In this way, the underground gas can be explored continuously.
[0018]
【The invention's effect】
Since the present invention is as described above, the following effects can be achieved.
<A> Before starting the actual excavation work, it is possible to determine the presence or concentration of a harmful gas such as hydrogen sulfide, the presence or absence of a flammable gas such as methane, the concentration, or the oxygen concentration. Therefore, it is possible to prevent accidents and take precautions beforehand.
<B> When investigating the gas generation state at a plurality of depths, it is not necessary to raise and lower the exploration rod at every investigation stage as in the conventional method, and a quick investigation can be performed.
<C> In the apparatus and method of the present invention, a packer is provided closer to the base than the gas sampling section, and the packer blocks the space between the exploration rod and the hole wall. For this reason, no harmful gas leaks from the gap to the ground, so it is possible to investigate safely for a long time.
<D> Work that uses liquid like mud boring is not involved. Therefore, it can be adopted even in places such as managed waste disposal sites.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of an embodiment of an exploration rod according to the present invention.
FIG. 2 is an explanatory diagram of a search state.
FIG. 3 is an explanatory diagram of a search order.
FIG. 4 is an explanatory diagram of a search order.
FIG. 5 is an explanatory diagram of a search order.
FIG. 6 is an explanatory diagram of a search order.
FIG. 7 is an explanatory diagram of a packer control circuit.
FIG. 8 is an explanatory diagram of a measurement circuit for the amount of gas discharged.
FIG. 9 is an explanatory diagram of a generated gas collection and analysis circuit.

Claims (2)

It consists of a probe and a press-fitting device that pressurizes the base of the probe and presses the tip into the ground.
The exploration rod
A pressure sensor that attaches to the vicinity of the tip and detects the atmospheric pressure outside the exploration rod, and
A gas suction port that opens toward the outside near the tip of the probe and sucks and collects gas outside the probe,
It can be expanded to the outer periphery of the exploration rod, and consists of a pressure sensor and a packer attached to the base side of the gas suction port with respect to the exploration rod.
Underground gas exploration equipment. A pressure sensor that detects external atmospheric pressure;
A gas suction port for sucking and collecting external gas;
The exploration rod that can be expanded to the outer periphery and is composed of a packer attached to the base side from the pressure sensor and gas suction port to the exploration rod,
Pressurize the base of this exploration rod and press the tip into the ground,
After that, the exploration rod is pulled out from the ground by a certain distance to form a cavity at the tip,
Close the space between the exploration rod and the hole wall by expanding the packer,
Measure the amount of spillage by detecting the pressure of gas collected in the cavity at the tip,
At the same time collecting the generated gas,
Exploration method for underground gas.

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