JP2000009631A - Water permeability tester for rock sample - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water permeability tester capable of accurately obtaining measurement results of a hardly water permeable rock bed material under a condition of high restraining pressure, high pore water pressure and a relatively low hydraulic gradient, the same as at a deep underground part. SOLUTION: A water permeability tester for a rock sample is constituted of a hydrostatic pressure triaxial testing container 2, three pressure-resistant syringe pumps 8, 9, 10 equipped with flow rate/pressure sensors injecting and sucking a fluid and detecting the flow rates and pressures of the fluid, the syringe pump controller 11 for controlling the flow rates and pressures of three pressure-resistant syringe pumps, the piping P connecting three pressure-resistant syringe pumps and the testing container 2, a differential pressure gauge 6 for detecting the difference pressure generated between both ends of the sample on the upstream and downstream sides thereof and a data recording part 12 receiving the output data from the syringe pump controller and the differential pressure gauge to record the same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water permeability test apparatus capable of measuring the water permeability of a rock specimen with high accuracy. More specifically, the present invention relates to an apparatus for measuring the permeability of a rock specimen having relatively small permeability. The present invention relates to a permeability test apparatus which can be quickly and accurately obtained under conditions of high confining pressure, high pore water pressure, and relatively low hydraulic gradient close to the current position conditions.

[0002]

2. Description of the Related Art Permeability is one of the important properties of formations and is closely related to various underground developments and uses. In particular,
Nowadays, concerns about environmental issues are increasing, and poorly permeable formations and their ground or rock materials are being studied and used as treatment and disposal sites for hazardous substances including radioactive wastes and as artificial barriers, and their extremely low permeability. Accurate measurement
Evaluation is indispensable for environmental protection and facility safety design.

[0003] As the existing main laboratory water permeability test methods for rock and ground materials, there are a constant water permeability test method, a variable water permeability test method, a transient pulse permeability test method, and a flow pump permeability test method. Generally, the constant water permeability test method is used to test a specimen having a relatively high permeability (10 ⁻² to 10 ⁻³ cm / s), and the variable water permeability test method is used for a relatively low permeability ( 10 ⁻³ to 10 ⁻⁷ cm / s). In addition, the transient pulse permeability test method and the flow pump permeability test method have lower permeability coefficients (<10 ^−7).
cm / s), which is a test method suitable for poorly permeable materials. However, in the water permeability test of a poorly permeable material, pressure burettes were installed on the inflow side and the outflow side of water, respectively, and a high osmotic pressure was applied between both ends of the test body. In many cases, measurements are made and a fixed or variable water permeability test is performed.
This is because the test method is simple and can be easily performed.

However, when the permeability characteristics of a poorly permeable rock material at a deep underground are measured by using the above-mentioned various conventional permeability test methods, there are the following disadvantages. (1) In the three types of permeability test methods except the transient pulse permeability test method, pore water pressure cannot be applied until the underground water pressure in the deep underground can be reproduced. For example, even in a constant water level permeability test method or a variable water level permeability test method using a pressurized burette tube, the maximum pressure is only about 10 kgf / cm ² . (2) In the transient pulse permeability test method, a relatively high pore water pressure can be applied. However, in most cases, a hydraulic jack is used as a pressurizing method, so that the pore water pressure rapidly increases. At the same time, in the initial stage of pressurization, extremely high hydrodynamic gradients were generated at both ends of the specimen,
Due to the consolidation and the movement of particles caused by this, the water permeability of the test specimen is impaired, and a numerical value lower than the actual water permeability coefficient can be obtained. However, this is not considered yet. (3) In the constant water level or variable water level permeability test method using a pressurized burette tube for measuring the permeability property of a poorly permeable rock material, the hydraulic gradient was made extremely high to facilitate the measurement of the flow rate. In this case, the osmotic pressure causes a consolidation phenomenon or turbulence, and the movement of the particles causes clogging or erosion of the gap, so that the measured hydraulic conductivity significantly differs from the actual permeability. On the other hand, when conducting a permeability test under low hydrodynamic gradient conditions, a very long time is required for measurement, and there is a problem in practicability and reliability. Conventional methods have technical limitations for controlling low hydraulic gradients and measuring small flow rates, and also cause experimental errors due to deformation of the test equipment itself due to changes in the environmental temperature during the test. I do. Furthermore, since the measurement is performed over a long period of time, evaporation, growth of bacteria, and chemical change of pore water during infiltration may cause errors in experiments. Therefore, when conducting a water permeability test of a poorly permeable material by the constant water level permeability test method or the variable water level permeability test method, the problems of the hydrodynamic gradient and the lengthening of the test are inevitable. (4) In order to accurately evaluate the permeability of the poorly permeable rock material, the size of the specimen and the magnitude of the permeability are
In both the flow pump permeability test method and the transient pulse permeability test method, the time required for the permeability test is several minutes to tens of hours. Due to the change in the environmental temperature during the measurement time, there is a possibility that it is not possible to accurately measure a temporal change in the differential pressure generated between both ends of the test body, which is necessary to calculate the hydraulic conductivity of the test body. This is because, when the inside of a closed container is filled with water, the material of the container and the coefficient of thermal expansion and compression of the water are different, so that the water pressure in the container also changes due to a change in temperature. Conventionally, when performing temperature control, air conditioning is used, but in this case, the room temperature fluctuates periodically, and the effect of constant temperature control that is actually expected cannot be obtained. (5) Most of the conventional test devices can perform only a specific permeability test in most cases. It is no exaggeration to say that the permeability test method for poorly permeable rock material is still not fully established. Therefore, cross-checking of various test methods may be necessary to obtain a relatively reliable permeability coefficient of a poorly permeable material. A possible test rig has not yet been developed.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned disadvantages of the prior art, and is directed to a material having low permeability, which has the same high confining pressure, high pore water pressure and relatively low It is an object of the present invention to provide a permeability test apparatus capable of accurately obtaining a measurement result under a condition of a hydraulic gradient. Another object of the present invention is to provide a general-purpose water permeability test apparatus which can be applied to various indoor water permeability test methods and has automatic data recording. It is still another object of the present invention to provide a water permeability test apparatus capable of minimizing the effect of a change in the temperature of outside air on a water permeability test and obtaining a more reliable measurement result.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a hydrostatic triaxial test container in which a rock specimen to be measured is set, and a flow / pressure for injecting and sucking a fluid and detecting the flow rate and the pressure of the fluid Three pressure-resistant syringe pumps with sensors, a syringe pump controller for controlling the flow rate and pressure of the three pressure-resistant syringe pumps, and a connection between the three pressure-resistant syringe pumps and the test container Piping, a differential pressure gauge for detecting a differential pressure generated between both ends of the upstream and downstream sides of the specimen, receiving output data from the syringe pump controller and the differential pressure gauge, and recording these data. A data recording unit for performing the measurement, wherein the three pressure-resistant syringe pumps are connected to a first syringe pump connected to an upstream side of the specimen and a third syringe pump connected to a downstream side of the specimen. And the syringe pump,
An apparatus for testing the permeability of a rock specimen is provided, the apparatus comprising a third syringe pump for applying a confining pressure to the specimen.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be described below based on examples. FIG. 1 is a schematic diagram showing a configuration of a water permeability test apparatus according to one embodiment of the present invention. 1 in the figure
Is a rock specimen (hereinafter also referred to as a specimen), 2 is a hydrostatic triaxial test vessel, 3 is an upstream storage tank, 4 is a downstream storage tank, 5
Is a temperature sensor, and 6 is a differential pressure gauge, which are installed in the first constant temperature chamber R1. 7 is a temperature sensor,
Reference numerals 8, 9, and 10 denote syringe pumps A, B, and C, respectively, which are installed in the second constant temperature chamber R2. 11
Is a syringe pump controller, 12 is a personal computer, 1
3 is a data logger, V1 to V14 are valves, P1 to P1
1 is a pipe, 14 is a temperature sensor.

The rock specimen 1 is a measurement target of the present apparatus,
Basically, a cylindrical shape is used, but other shapes can also be used. The hydrostatic triaxial test container 2 is for applying a confining pressure to the test body 1 in a hydrostatic pressure state. The circumferential pressure assumed for the test body 1 varies depending on the target depth. For example, a high-level radioactive waste disposal facility is constructed at a depth of 1000 m or more underground, and the ground pressure at that point becomes considerably high (when the unit volume weight of rock is 2.5 t / m ³ , the overburden pressure of its own weight is 25 MPa).
become). Therefore, in order to be able to reproduce even a high confined pressure under such a large depth underground, a hydrostatic triaxial test vessel having a design withstand pressure of 100 MPa was used in the present embodiment. Specifically, a cylindrical test body 1 is sandwiched between a porous metal and two pedestals having a center hole for water permeability, and the peripheral side surface is covered with a rubber sleeve. These are further set between two disks with three bolts, a silicone rubber is applied to a thickness of about 5 mm on the rubber sleeve and a slightly exposed portion of the pedestal, dried, and then triaxially set with three bolts. It is set in the triaxial test container 2 while being hung on the lid of the test container. The two disks and the pedestal can move relatively to the axial direction of the specimen, and the rubber sleeve itself has flexibility,
Specimen 1 with confined pressure medium filled in triaxial test vessel 2
When a pressure is applied to the test piece 1, the test body 1 receives a load in a hydrostatic pressure state. The predicate “binding pressure” used in this specification will be described below. Underground pressure exists due to the weight of the stratum. A sample taken from the ground is originally under stress from the surrounding stratum and is in a restrained state.
In order to reproduce the underground stress state, in the indoor water permeability test, a pressure corresponding to the underground stress value is applied to the specimen through a rubber sleeve or the like coated on the specimen. The pressure applied to the test piece in this way is referred to as “constrained pressure”.

The pressure-resistant syringe pumps A (8) to C (1)
0) is for injecting and suctioning a fluid, and has a built-in sensor for measuring a flow rate and a pressure, respectively. What should be noted when using these syringe pumps is the flow rate and pressure resistance of the pump. Regarding the design of a constant flow rate of a pump when used in the flow pump permeability test method, the current technical level has a limitation on a minute flow rate that can be realized by the flow pump permeability test. Further, when a low pressure is measured by a measuring instrument having a certain precision and resolution, a relative error is larger than that of a high pressure measurement. Therefore, in order to accurately measure the hydraulic conductivity, it is necessary to appropriately set the discharge amount in the flow pump permeability test. The pump flow rate was set by calculating the steady state pressure in the flow pump permeability test based on Darcy's law. As for the pressure resistance, the test piece 1 was assumed to be deep underground (1000 m or more).
Was set to 10 MPa or more. From the above conditions, in this embodiment, the syringe pump 10 manufactured by ISCO was used.
0Dseries was selected as the syringe pump. This device is composed of a syringe pump body capable of injecting and sucking a fluid with a constant, ultra-fine flow rate with precision, non-pulsating flow, and a controller that controls it.It is possible to control a wide range of flow rate and pressure, and its accuracy is also high. It is expensive. The flow rate of the syringe pump used in this embodiment is 0.01 to 5000.
0μl / min 6 order, pressure 69kPa to 69MP
a (approximately 700 kgf / cm ² , which corresponds to a ground pressure of 3000 m or less underground).
control and detection (up to μl / min) and pressure (up to 1 psi). In this embodiment, the syringe pump is also used as a restraint pressure generating means by utilizing the high pressure control ability.

The syringe pump A (8) plays a role of gradually increasing the pore water pressure in various permeability tests, and controls the flow rate and pressure on the upstream side (water injection side) by its built-in flow rate and pressure sensor in various permeability tests. Perform the role of detection. That is, the syringe pump A (8) applies a constant fluid pressure to the upstream side in the case of the constant water level permeability test, detects a change in the flow rate flowing into the test body, and in the case of the flow pump permeability test, Inject into the specimen at a constant fine flow upstream
In the case of the transient pulse permeability test, it is used as the upstream storage tank 3 or a part thereof. The syringe pump B (9) has a function of detecting the downstream flow rate and pressure by its built-in flow rate and pressure sensor in various water permeability tests. That is, in the case of the constant water level permeation test, a constant fluid pressure is maintained on the downstream side to detect a change in the flow rate flowing out of the test piece 1. In the case of the flow pump permeation test, the downstream side (water outflow) is detected. Side), a constant fluid pressure is maintained, and in the case of a transient pulse permeation test, it is used as the downstream storage tank 4 or a part thereof. Syringe pump C (1
0) fills the hydrostatic triaxial test container 2 with a confining pressure liquid medium (antifreeze rust preventive and water) and pressurizes the confining pressure.

The upstream pressure storage tank 3 and the downstream pressure storage tank 4 are installed on the upstream side and the downstream side of the specimen 1, respectively.
Used as a pressure buffer tank in transient pulse permeability tests.

The temperature sensors 5, 7, and 14 detect the temperature at each measurement point, and the detected data is stored in TDS-302 and GP-
The data is sent to the personal computer 12 via the IB, and the personal computer 12 measures and monitors the temperature at each measurement point and its change. Pressure measurement is greatly affected by changes in temperature, so the temperature is monitored and used as basic data for measurement accuracy. In this embodiment,
The temperature sensor 5 is installed in the pipe on the upstream side of the water permeability test, detects the temperature of the water for the water permeability test and the temperature in the constant temperature chamber R1, and the temperature sensor 7 is installed in the center of the constant temperature chamber R2. The temperature in the constant temperature chamber R2 is detected, and the temperature sensor 14
Is installed about 2m away from the personal computer 12,
Detects outside air temperature. It is to be noted that a temperature sensor can be provided at an appropriate measuring point as needed to detect the temperature.

The differential pressure gauge 6 is used for detecting a differential pressure generated between the upstream and downstream ends of the test piece 1. The movement of the permeable fluid in the pipe is relatively slow, and the resistance to fluid movement generated in the pipe is much smaller than the resistance generated by the specimen 1. That is, it can be assumed that the movement of the fluid in the piping does not cause a water pressure loss. Therefore, the differential pressure gauge 6 installed between the upstream and downstream pipes can detect the difference in water pressure generated between the upper and lower boundary surfaces of the test body 1 with high accuracy. In the present embodiment, a validator DP363 high line pressure standard type manufactured by Validine was used as a differential pressure gauge. The differential pressure gauge DP363 can change the internal diaphragm to ± 0.56 × 10 ⁻³ to ± 880.
± 0.25% over a wide range of kgf / cm ² within the specified range
It is possible to measure with full-scale high accuracy.

The syringe pump controller 11 has three
The flow rates and pressures of the two syringe pumps A (8), B (9), C (10) are controlled and detected independently and simultaneously with high accuracy, and the values are displayed on a monitor. Further, the controller 11 can control the state of the pore water by two kinds of control methods, that is, a flow rate control and a pressure control. In the flow rate control mode, control is performed so that the syringe pump injects or sucks the liquid at the set constant flow rate. In the constant pressure control mode, control is performed so that the syringe pump automatically injects or sucks the liquid so as to maintain the set constant pressure.
In both control modes, the pressure of the operating syringe pump,
Both the flow rates are displayed on the monitor screen of the controller 11, and connected to the personal computer 12 by RS232C,
The data can be automatically recorded together with the output from the data logger 13 by dedicated measurement software.
As a result, not only the head difference between the entire lengths of the test specimen 1 during the water permeability test, but also the pressures at the upper and lower ends of the test specimen 1 can be accurately measured, and more reliable data can be obtained. Become.

The personal computer 12 automatically records data such as the flow rate of the syringe pump, the pressure value, the output of the differential pressure gauge, and the temperature inside the pipe and around the test apparatus by using dedicated software, and simultaneously records each data along the time axis. By plotting the graph on a monitor, it is easy to monitor and monitor the experiment over a long period of time. As a result, by observing the head difference between the specimens during the experiment and changes in all other measured values as needed,
Steady / unsteady judgment can be clarified. The data logger 13 processes and amplifies an analog signal from each sensor (temperature sensor or differential pressure gauge), converts the analog signal into a digital signal, and transfers the digital signal to the personal computer 12 via the GP-IB.

A pipe P1 connects the syringe pump A (8) to the upstream side of the test piece 1, and a pipe P2 connects the syringe pump B
(9) is connected to the downstream side of the specimen 1, and the pipe P3 is connected to the syringe pump C (10) and the lower part of the triaxial sample container 2. Pipes P6, P5, and P4 are also connected to the syringe pumps A (8), B (9), and C (10), respectively. Piping P
1 is connected in parallel with a pipe P7, an upstream storage tank 3, and a pipe P8. On the other hand, a pipe P9, a downstream storage tank 4 and a pipe 10 are connected in parallel to the pipe P2. In addition, pipe P1
And the pipe P2 are separately connected by a pipe P11 and a pipe P12. Further, a pipe 13 is connected above the triaxial test container 2.

In the middle of the pipe P1, valves V6, V14
Are mounted, and valves V4 and V9 are provided in the middle of the pipe P2.
Is mounted, and a valve V2 is mounted in the middle of the pipe P3. Valves V for pipes P4, P5 and P6
1, V3 and V5 are respectively attached. Piping P
Valves V13, V12, V7, B8, V10, and V11 are mounted in the middle of 7, P8, P9, P10, P11, and P13, respectively. A differential pressure gauge 6 is mounted in the middle of the pipe P12. Appropriate switching of each of the above valves can deal with refilling of the fluid into the syringe pump, execution of various water permeability tests, and the like.

In this embodiment, since the test is performed under high pressure conditions, pipes and valves used for high pressure made of stainless steel are used. Further, in order to minimize the influence of temperature on the water permeability test, the piping section was made as short as possible, and furthermore, styrene foam was processed and wound to provide heat insulation. In order to completely prevent leakage, the connections of the pipes were made by welding as much as possible.

Next, a set of test specimens 1 and a triaxial test vessel 2
How to apply pressure (constraint pressure) to the inside will be described. First,
Close the valve V2, open the valve V1, set the syringe pump C (10) to the constant flow mode by the syringe pump controller 11, and (re) fill the pump with water (note that each syringe pump is refilled with water). Plumbing,
That is, the ends of the pipes from the valve V1, the valve V3, and the valve V5 are all placed in a deaerated water or distilled water storage container, but are not shown in the figure). Thereafter, the valve V1 is closed, the valve V2 is opened, and water is injected to the bottom of the triaxial test container 2 via the pipe P3 connected between the valve V2 and the triaxial test container 2 in the constant flow rate mode. afterwards,
An appropriate amount of antifreeze anticorrosive is put directly from the upper part of the triaxial test container 2 and the test piece 1 is set. Then, the triaxial test container 2 is closed with the valve 11 opened. Then, the triaxial test container 2 was set by the constant flow rate mode of the syringe pump C (10).
Inject water until the air inside is completely displaced. Thereafter, the valve V11 is closed, and pressure is applied to a predetermined confining pressure by the constant pressure mode of the syringe pump C (10). still,
When the water in the syringe pump runs short, it can be refilled repeatedly while maintaining a high pressure state by switching the valves V1 and V2 to close and open.

When performing any of the water permeability tests using the apparatus of this embodiment, it is necessary to apply pore water pressure in order to reproduce the pressure of groundwater deep underground. In the present invention, the pore water pressure is applied as follows. Fill all piping and reservoirs for the permeability test with water. Close valves V3 and V5,
Valves V6, V7, V8, V9, V10, V12, V1
3. With the V14 opened, the syringe pump B (9) is stopped by the syringe pump controller 11, and the syringe pump A (8) is gradually increased in pore water pressure in a constant minute flow rate mode to check the pressure increase state. Monitor. Immediately before the pore water pressure reaches a predetermined value, the syringe pump A (8)
Is stopped, and then the syringe pump A (8) is switched to the constant pressure mode and pressurized. During the pressurization process, the change over time in the flow rate is monitored, and pressurization is continued until the flow rate becomes zero. By such a method of pressurizing the pore water pressure, a rapid change in the water pressure in the test body 1 is prevented, and the water permeability test can be performed without disturbing the test body 1.

Various water permeability tests are performed by the following procedures in a state where a predetermined confining pressure and pore water pressure are applied by the above-described method.

Constant Water Permeability Test Method First, the outline of the constant water permeability test will be described with reference to FIG. In this test, a constant water level difference is given to the test body, the amount of water per unit time is measured, and the water permeability coefficient K is calculated from the following Darcy's rule. K = (q / At) · (L / ΔH) Here, q is the water permeability, t is the measurement time, ΔH is a constant pressure difference between the test pieces, L is the height of the test pieces, and A is the height of the test pieces. Cross section,
ΔH / L is a hydraulic gradient. In addition, the "hydraulic gradient" is a head difference per unit length.

In the procedure, the valve V10 is slowly closed, and the syringe pump A (8) and the syringe pump B (9) are controlled by the syringe pump controller 11 in the constant pressure mode to P _A and P _B (the same value as the initial pore water pressure, respectively). ) And activate. Then, a pressure corresponding to P _A -P _B is applied to both ends of the specimen 1, and this pressure is applied to the specimen 1.
Is the differential pressure applied to both ends. Then, syringe pump A
The change over time in (8) and the flow rate of the syringe pump B (9) is measured and monitored, and the test is performed until both flow rates become the same value and a steady state is reached. The hydraulic conductivity of the test body 1 is determined by the Darcy's law using the flow rate measured in the steady state and the differential pressure value measured with high accuracy by a differential pressure gauge.

The following advantages are obtained by comparing this constant water level permeability test method with the conventional constant water level permeability test method. 1) A high pore water pressure is applied to reproduce the water pressure of deep groundwater. 2) The system is completely sealed, and no measurement error occurs due to evaporation or the like. 3) It is possible to measure and monitor the change in flow rate with a resolution of 0.01 μl / min, so that the measurement accuracy is high, it is easy to judge the steady state, and even in the case of a poorly permeable specimen,
Permeability can be measured quickly. That is, the measurement range of the permeability coefficient is much wider, the measurement time is shorter, and the measurement accuracy is higher than the conventional constant water permeability test method.

Flow Pump Permeability Test First, the outline of the flow pump permeability test will be described with reference to FIG. In this test, the fluid flowing into or out of the test specimen 1 is externally controlled, and the hydraulic head difference between the test specimens due to the control is measured to determine the hydraulic conductivity. The characteristic of this test method is that the constant water level method or the variable water level method described above controls or changes the pressure to a constant value, measures the micro flow rate, and obtains the hydraulic conductivity, while controlling the micro flow rate to a constant value and controls the pressure. By directly measuring, the test can be easily and accurately performed.

The procedure will be described.
8, V12 and V13 are closed, and after the pore water pressure is stabilized, the valve V10 is further closed slowly. After that, the syringe pump controller 11 sets the syringe pump A (8) and the syringe pump B (9) to a constant flow rate and a constant pressure (the same value as the initial pore water pressure) mode, respectively, and operates them. In the initial state of the test, the pressure difference is 0, but by injecting water into the test piece 1 from the syringe pump A (8), a differential pressure is generated (induced) at both ends of the test piece 1. During the test, a time-dependent change in the differential pressure generated between both ends of the test body 1 is measured and monitored by the differential pressure gauge 6, and the measurement is continued until the differential pressure becomes constant (steady state).
The hydraulic conductivity of the test body 1 is determined by the Darcy's law using the differential pressure in the steady state and the set minute flow rate.

The flow pump permeability test method is characterized in that the maximum hydraulic gradient generated in the test body during the permeability test can be controlled by setting the flow rate of a syringe pump that injects water into the test body, as compared with all other permeability test methods. It is. In addition, the flow pump permeability test method of the present invention enables a test under higher pore water pressure conditions than the conventional flow pump permeability test method.

[0028] Transient Pulse Test First, a description will be given of a schematic of the transient Pulse Test in FIG. In this test, two fluid reservoirs are connected to a basically cylindrical rock specimen. Then, a pressure pulse is suddenly applied to one of the storage tanks from a state in which pore water pressure is applied to the test body. The fluid gradually penetrates from the storage tank to which the pressure pulse was applied, passes through the test specimen, and into the other storage tank,
At the same time, the pressure in the storage tank to which the pressure pulse is applied gradually decreases. The hydraulic conductivity is determined from the change over time in the water pressure of the storage tank connected to the specimen. In FIG. 4, Hu and Hd indicate the water pressures in the upstream and downstream storage tanks, respectively.

In the procedure, the valve V10 is slowly closed, and then the syringe pump controller 11
To stop the syringe pump A (8) (the syringe pump B (9) is already stopped). Then, by rapidly closing the valve V12 (it is necessary to open the valve V12 fully in advance), the upstream water is compressed in the upstream storage tank 3, and
A pressure pulse is generated. By measuring the time-dependent decrease of the pressure pulse with a high-precision differential pressure gauge, the hydraulic conductivity of the specimen 1 is calculated.

The transient pulse permeability test method has the following advantages as compared with the conventional transient pulse permeability test method. 1) From the flow rate and pressure curve of the high-precision syringe pump, the compression storage characteristics due to changes in the pressure of the storage tank and the entire piping system can be accurately obtained. 2) By adopting a high-precision pressure-resistant syringe pump, the precision of the confined pressure control during the experiment is increased, and even when the water permeability of the specimen is extremely small, it can sufficiently cope with long-term measurement. 3) The capacity of the storage tanks on the upstream and downstream sides can be adjusted according to the dimensions and hydraulic characteristics of the test body, so that experiments can be performed more efficiently. 4) Strict constant temperature measures are implemented, and the upstream and downstream permeability test facilities are symmetrical, so that the effect of temperature changes on the permeability test can be minimized. As a result, the pulse pressure at the initial stage of the test and the hydraulic gradient in the test object can be further reduced as much as possible, and as a result, a measured value closer to the current position condition can be obtained.

Here, a countermeasure against a change in environmental temperature performed in the present embodiment will be described. 2 for test room temperature changes
There are two major causes. One is due to changes in outside air temperature and the other is due to heat generated by pumps and measuring instruments. Insulation was applied to the walls of the measurement room against changes in outside air temperature. In addition, the three-axis compression test container and the storage tank, the syringe pump main body, the syringe pump controller, the personal computer, and the data logger were installed in separate rooms in order of distance from the outside air side. As a result, in the test room having the triaxial compression test container and the storage tank, the temperature change in the day was near ± 3 ° C. at first, but was successfully suppressed to ± 0.5 ° C. However, the value is not perfect because the value changes greatly depending on the season and the change in the outside temperature on that day.However, by constantly monitoring and recording the temperature at the time of measurement, it is possible to select a time zone where the temperature change is relatively small during the day. If the permeability test is completed within a few hours, the change in temperature during the test period is 0.1%.
There is a possibility to keep it within ° C.

[0032]

According to the present invention, the following remarkable effects can be obtained by employing the above-mentioned structure. (1) Low permeability material under high confinement pressure and high pore water pressure (up to 69 MPa, up to about 700 kgf / cm ² ) that can reproduce the ground pressure and water pressure conditions deep underground with one permeation test device However, the water permeability test of any one of the constant water permeability test method, the flow pump permeability test method, and the transient pulse permeability test method can be performed without changing the physical properties of the specimen. (2) Compared to the conventional device, a highly accurate measurement result can be obtained in a very short time. (3) Permeability test can be performed under conditions of low dynamic gradient near the current position. (4) The effect of the temperature change of the outside air on the permeability test is minimized, and highly accurate data can be obtained. (5) The technology of this device is basic and is useful in all fields where the permeability of rock material needs to be evaluated. In particular, the isolation and shielding performance of poorly permeable rock material can be improved with higher accuracy. This is very important in the field of environmental control technology related to geological disposal of waste that needs to be evaluated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a water permeability test apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory diagram of a constant water level permeability test.

FIG. 3 is a schematic explanatory diagram of a flow pump permeability test.

FIG. 4 is a schematic explanatory diagram of a transient pulse permeability test.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Rock test body 2 Hydrostatic triaxial test container 3 Upstream storage tank 4 Downstream storage tank 5, 7, 14 Temperature sensor 6 Differential pressure gauge R1, R2 Constant temperature chamber 8, 9, 10
Syringe pump 11 Syringe pump controller 12 Personal computer 13 Data logger V1 to V14
Valve P1 to P13 Piping

Claims (4)

[Claims] 1. A hydrostatic triaxial test container in which a rock test object to be measured is set, and a flow / pressure sensor for injecting and sucking a fluid and detecting a flow rate and a pressure of the fluid. Three pressure-resistant syringe pumps, a syringe pump controller for controlling the flow rate and pressure of the three pressure-resistant syringe pumps, and a pipe for connecting the three pressure-resistant syringe pumps to the test container. A differential pressure gauge for detecting a differential pressure generated between the upstream and downstream ends of the test body; a data recording device for receiving output data from the syringe pump controller and the differential pressure gauge and recording these data A first syringe pump connected to an upstream side of the specimen and a second syringe connected to a downstream side of the specimen. An apparatus for testing the permeability of a rock specimen, comprising a syringe pump and a third syringe pump for applying a confining pressure to the specimen. 2. The water permeability test apparatus according to claim 1, wherein fluid storage tanks connected to the first and second syringe pumps are provided on the upstream side and the downstream side of the test body, respectively. . 3. A pipe upstream and downstream of the test piece,
The permeation test device according to claim 2, further comprising a valve for switching between connection and disconnection with the fluid storage tank. 4. The permeation test apparatus is installed in a thermostatic chamber, and includes a temperature sensor for measuring at least a temperature of water for permeation test, a temperature in the thermostat chamber, and a temperature of outside air.
4. The water permeability test apparatus according to claim 1, wherein output data from the temperature sensor is sent to the data recording unit.