JP2004361193A - Water permeability test apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily perform the in-situ collection of samples and implement highly precise water permeability tests on the collected samples under a pressurized condition in a triaxial state similar to their original positions. <P>SOLUTION: This water permeability test apparatus is used as a sampler at the in-situ collection of a sample 2 and can house the sample 2 in an inside sample housing space 21 while holding its collected state. The water permeability test apparatus is provided with a sample housing casing 20 having both a pressurizing means having a pressurizing cylinder chamber 22 provided with a bellowphragm 30 via a water passing pressurizing plate and a drain route for draining water passed through the sample 2 via a water passing pressurizing plate 28 at permeability tests; a base block 10 which supports one surface of the sample 2 at an inside water passing support plate 14 and in which a water supply route for supplying water for a sample surface via a water passing support base at permeability tests is formed; connecting means for tightly and detachably fixing the sample housing casing 20 to the base block 10: and a measuring means capable of measuring the quantity of water drained through the sample 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a water permeation test apparatus, and relates to a water permeation test apparatus that can be carried and also serves as a sampler for collecting a sample at a test position, and can perform a highly accurate test on the collected sample under a predetermined pressure condition.
[0002]
[Prior art]
In recent years, construction of final disposal sites for large-scale general waste has been promoted in various places. At these facilities, sufficient water-impervious works are installed so that leachate from accumulated waste does not leak outside the site. It is necessary. Bentonite mixed soil or the like is often used as the water barrier. In proceeding with this water-impervious work, it is necessary to measure the water-permeability coefficient of the water-impervious material at a large number of measurement points in a wide range in order to confirm the water permeability (water-impervious) of the construction site. In addition, it is necessary to measure the in-situ permeability coefficient of the core material constituting the water-impervious zone in a fill dam or the like.
[0003]
As a method of determining the permeability coefficient of the target ground, a test hole is provided in the original ground by boring or the like, and the water level in the test hole is lowered to measure the recovery status or the rate of water level drop, or to maintain a constant water level. Is used to obtain the hydraulic conductivity from the amount of water supplied. In addition, there is a method of collecting a sample at an original position and performing a water permeability test under a triaxial stress state in a test room (for example, see Patent Document 1).
[0004]
[Patent Document 1]
See JP-A-7-306198.
[0005]
In the former field test, in addition to problems such as the fact that the actual shape of the test hole and the flow of water do not completely match the theoretical formula and the point where the saturation conditions are unclear, it takes a long time to measure on low-permeability ground. Therefore, there is also a problem that the work of the impermeable work cannot be performed during that time. In the latter laboratory test, it is difficult to secure an undisturbed sample, and the laboratory testing machine becomes large, and it is difficult to test a large number of samples, and the test cost also increases.
[0006]
[Problems to be solved by the invention]
Therefore, in view of the problems of the above-described existing test methods and test apparatuses, it is important that the water permeability test apparatus of the present invention is an apparatus that can solve the following specific problems. That is,
(1) Permeability test is possible without disturbing the original ground (2) Test is possible under the condition that the theoretical formula for water permeability can be applied (3) The load condition of the original ground can be reproduced ▲ 4 ▼ Small and portable as a device, simple and robust structure, easy to use in the field ▲ 5 ▼ Able to handle a large number of measuring points ▲ 6 ▼ Tests at sampling points (measuring points) Short restraint time (7) High test accuracy.
(8) Permeability direction of raw ground (eg horizontal and vertical directions) can be tested arbitrarily. (9) The device can operate without power supply.
Accordingly, an object of the present invention is to provide a water permeation test apparatus that takes into account the points of the above-described conventional techniques.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a pressurizing means for pressurizing a sample accommodated in an internal sample accommodating space while maintaining a sampling state in its original position through a water pressure plate, and the water flow A sample container having a drainage channel for draining water that has passed through the sample during a water permeability test through a pressure plate, and supporting one surface of the sample by an internal water flow support plate when in close contact with the sample container And a base member in which a water supply path for supplying water to the sample surface during the water permeability test is formed through the water flow support plate, a connecting means for closely fixing the sample storage container to the base member, and the sample And a measuring means capable of measuring the amount of water discharged through the water.
[0009]
The pressurizing means includes a piston mechanism that reciprocates in a pressurizing cylinder chamber that is continuously provided in the sample storage space, and presses the water pressure plate by the operation of the piston mechanism, The water permeability test can be performed with the sample in the triaxial stress state of the same level as the original position. The piston mechanism is preferably operated with compressed air supplied from the outside.
[0010]
Alternatively, the pressurizing means includes a spring mechanism housed in a pressurization cylinder chamber provided continuously in the sample housing space, and presses the water pressure plate by the operation of the spring mechanism, and the sample housing space. It is preferable to conduct the water permeability test with the sample in the same triaxial stress state as the original position.
[0011]
The sample storage container has a cutting edge at the lower end, and at the time of sample collection, it is preferable that the container is driven into the ground surface from the cutting edge to take the sample into the sample storage space. At this time, the sample in the sample storage space is removed. A triaxial stress state similar to the original position is preferable.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a water permeability test device of the present invention will be described with reference to the accompanying drawings. As shown in FIG. 1, the water permeability test apparatus 1 according to the present invention includes a base block 10 having a circular recess 11 having a predetermined depth at the center of the upper surface, and a peripheral portion of the circular recess 11 having a lower end at the base block 10. And a sample storage casing 20 that can pressurize the sample stored in the sample storage space 21 whose bottom surface is open and store the sample in a predetermined stress state.
[0013]
Hereinafter, each structure of the water permeability test apparatus 1 will be described. The base block 10 is a flat steel block that functions as a pedestal for the apparatus main body. A circular recess 11 having a predetermined depth is formed in the center of the upper surface, and a plurality of water passage holes 12a are formed in the upper surface thereof. The water flow plate support 12 is accommodated. On the water flow support 12, a water flow plate 14 whose periphery is held by a sealing material 13 is placed. In this embodiment, a porous ceramic plate is used as the water flow plate 14 as an example. When the water permeability coefficient of the sample 2 is relatively large, various natural or artificial porous plates such as porous stone can be used. A holding rod 15 is erected on the upper surface of the block around the circular recess 11. The holding rod 15 serves as a connecting means for tightly fixing the sample storage casing 20 onto the base block 10 by tightening a fixing nut 42 of a fastening flange 41 of a fixing jig 40 described later. Moreover, the water supply hole 16 which penetrates a block outer surface and the circular recess 11 is provided as a water supply path for a water permeability test.
[0014]
The sample storage casing 20 is used as a sampler (the operation procedure will be described later) that collects the sample 2 for the permeability test at the original position of the test position. It is a cylindrical steel member that is used as a part. As shown in FIG. 1, the sample storage casing 20 has a sample storage space 21 whose lower surface is hollowed out into a flat cylindrical shape having a predetermined diameter, and a cylindrical pressurization continuous to the upper portion of the sample storage space 21. A cylinder chamber 22 is formed. A water pressure plate 25 that can reciprocate while sliding along the wall surface of the space is accommodated in the sample storage space 21 by the operation of a piston 23 described later. This water pressure plate 25 has the same configuration as the water flow support base described above, and has a water flow plate holding frame 27 having a number of water holes 27a formed on the upper surface, and a water flow fixed to the lower surface recess. It consists of a plate 28. By attaching the O-ring 26 to the water flow plate holding frame 27, it is possible to maintain the water tightness between the inner wall of the sample storage space 21. The water flow plate 28 of the water flow pressure plate 25 is made of the same material as the water flow plate 14 described above.
[0015]
As shown in FIG. 1, the pressurized cylinder chamber 22 is expanded and contracted in the cylinder chamber 22 by compressed air introduced through an air supply passage 29 provided through the upper surface of the casing 20. A bellowram 30 made of synthetic rubber capable of expanding and contracting the entire length and a piston 23 positioned at the lower end of the bellophram 30 and reciprocating along the inner wall of the cylinder chamber 22 as the bellophram 30 expands and contracts are accommodated. The water pressure plate 25 is pressed at the lower end, and the sample 2 in the sample storage space 21 can be set to a predetermined pressure state.
[0016]
Further, in the casing 20, water at the time of the water permeability test passes through the sample 2 in the sample storage space 21 and is drained to an external burette, and inside the pressurized cylinder chamber 22 at the time of the water permeability test. And a drainage hole 33 for confirmation for draining a part of the water filled with water. Further, a water tank 35 is provided at the upper end of a stand pipe 34 as a water supply pipe outside the apparatus, and a burette 37 is provided as a measuring means at the time of the water permeability test on the drain pipe 36. A valve 38 (38A, 38B, 38C) is provided on the apparatus side on the water supply / drainage path, and when performing a water permeation test, the corresponding valve 38 is opened and closed by a predetermined procedure to supply water into the sample storage casing 20. The sample 2 is controlled for saturation, water permeability test, and drainage. Further, for other measurement items in the test, it is effective to measure the differential pressure between the compression air pressure gauge 45 and the air pressure on the air supply path 29 as the loading pressure on the sample 2 and the water pressure on the drainage paths 32 and 36. A stress meter 46 can also be provided.
[0017]
On the other hand, a fixing jig 40 as one component of the connecting means is screwed to the upper end of the sample storage casing 20. The fixing jig 40 has the same main body outer diameter as that of the sample storage casing 20, and a disk-like fastening flange 41 is formed on the upper part. By fastening the fixing nut 42 of the fastening flange 41 to the holding rod 15, the sample storage casing 20 can be tightly fixed on the base block 10. In addition, in FIG. 1, although the water flow state from the lower side to the upper side is shown in the figure, it is also possible to make the water flow direction upside down.
[0018]
Next, a procedure for collecting a sample at a test position using the sample storage casing 20 incorporated in the water permeability test apparatus 1 of FIG. 1 as a sampler will be described with reference to FIGS. In the following description, the sample storage casing 20 will be described as a sampler 20 in order to clarify its application. FIG. 2 (a) shows that the bellowram 30 in the pressurizing cylinder chamber 22 is inflated with compressed air for use as the sampler 20, and the piston 23 is pushed down at the lower end of the bellophram 30, so that the water pressure plate 25 in the sample storage space 21. Is lowered to the lower end of the sampler 20. In this state, a cylindrical hitting collar 5 is screwed to the upper end and used.
[0019]
In order to collect the sample 2 for the permeability test using this sampler 20, first, the surface of the ground 3 at the sample collection point (permeability test position) is smoothly shaped, and the guide tube 6 as shown in FIG. Install on the surface. The guide cylinder 6 has a cylindrical shape whose inner diameter is slightly larger than the outer diameter of the sampler 20 and whose overall length is longer than that of the sampler 20, and a circular flange 6a is integrally formed on the bottom surface. This circular flange 6a allows the guide tube 6 to stand on the ground surface. The sampler 20 can apply a predetermined vertical pressure to the sample 2 even when the sample is collected. For example, the sampler 20 can reproduce the stress state in which the loading load is applied when the embankment is completed. Generally, only a very small pressure is loaded and used. The pressure state is adjusted by adjusting the air pressure of the bellophram 30 in the pressure cylinder chamber 22 described above. As shown in FIG. 3, the sampler 20 in this state is housed in the guide cylinder 6, and the sampler 20 is driven into the ground 3 using the fall energy of the drive hammer 8 of the sampler 20 driving device 7. As the cutting edge 20 a formed at the lower end of the sampler 20 is driven into the ground 3, the piston 23 and the water pressure plate 25 rise and part of the ground 3 is taken into the sample storage space 21 as the sample 2.
[0020]
When the sampler 20 is driven into the ground 3 to a predetermined depth that fills the sample storage space 21 with the sample 2, the pressure in the bellophram 30 is reduced or released. As shown in FIG. 4, the underground portion of the sampler 20 is dug together with the surrounding ground block 4. Thereafter, the end surface 2a of the sample 2 is shaped smoothly using a shaping knife or the like. In this way, the sample 2 for a water permeability test that is not disturbed can be accommodated in the sample accommodation space 21 of the sampler 20. Although the sample height (thickness) depends on the assumed water permeability, it is usually possible to appropriately set about 15 to 50 mm with respect to φ75 mm. At this time, it is preferable to adjust the height by inserting an adjustment spacer or the like (not shown) into the sample storage space 21.
[0021]
Next, the sampler 20 holding the sample 2 is incorporated into the water permeation test apparatus 1 as the above-described sample storage casing 20 as shown in FIG. At the time of this assembly, as shown in FIG. 2B, the fixing jig 40 is screwed to the upper end of the sampler 20 after removing the striking collar 5 (see FIG. 2A). As shown in FIG. 1, the sampler 20 is placed on the base block 10, and the fixing nut 42 of the fastening flange 41 of the fixing jig 40 is screwed to the fastening rod 15 (FIG. 1) to fix the sampler 20. The circular recess 11 of the base block 10 is interposed via a ring-shaped sealing material 13 provided at the peripheral edge of the circular recess 11 so that the lower end cutting edge 20a is brought into close contact with the water plate 14 through the end surface 2a of the sample 2. Fix tightly to the periphery. Thereafter, the pipes 34 and 36 of the water supply and drainage paths and the air supply pipe 29 are connected to the apparatus 1.
[0022]
Hereinafter, the measurement of the water permeability coefficient using this water permeability test apparatus will be described. Prior to the water permeation of the sample 2, the triaxial stress state of the sample 2 in the sampler 20 is reproduced. For example, it is possible to reproduce the stress state and the like on which the overlay load is applied when the embankment is completed. The vertical load is performed by adjusting the air pressure of the bellophram 30 in the pressurizing cylinder chamber 22. First, the valves 38B and 38C on the drainage path are opened. Next, the valve 38 </ b> A on the water supply path 34 from the water tank 35 is opened to start water flow into the apparatus 1. Part of the water that has passed through the sample 2 is filled in the pressure cylinder chamber 22 and further drained to the outside through the drain hole 33. When this state is confirmed, the valve 38B is closed. Further, when the drainage from the drainage hole 32 is confirmed, the drainage amount (permeation amount) per unit time is measured by a measuring means such as a burette 37. Thereby, the water permeability coefficient of the sample 2 can be obtained. The pressurization of the belofram 30 can also be used to increase the effective restraining pressure of the sample when the hydraulic gradient during the water permeability test is increased.
[0023]
In the above description, as the pressurizing means, the bellophram 30 is provided in the pressurizing cylinder chamber 22 to pressurize the sample 2 using compressed air. However, the compression can be mechanically changed in the spring coefficient. It is also preferable that a spring or the like is built in the pressurizing cylinder chamber 22 to form a pressurizing means using a predetermined spring resistance. In this case, since an air supply means etc. are not required, the apparatus 1 can be made more compact.
[0024]
【The invention's effect】
As described above, according to the water permeability test apparatus of the present invention, a sample that is not disturbed in a short time can be collected using a sampler incorporated in a part of a simple and robust apparatus, and the sample is directly subjected to a water permeability test. The test conditions can also reproduce the same conditions as the permeability theory by realizing a simple unidirectional flow in the sample storage space. In addition, by appropriately setting the vertical load, the original ground and arbitrary load loading conditions can be reproduced, and a highly accurate water permeability test can be realized.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an embodiment of a water permeability test device according to the present invention in a partial cross section.
2 is a cross-sectional view showing a usage mode of a sampler (sample storage casing) of the water permeability test apparatus shown in FIG. 1;
FIG. 3 is an explanatory diagram showing a sample sampling state using the sampler shown in FIG. 2 (injected state).
FIG. 4 is an explanatory diagram showing a sample sampling state (sample collection state).
FIG. 5 is an explanatory diagram showing a sample sampling state (sample shaping state).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Water permeability test apparatus 2 Sample 10 Base block 11 Circular recess 12 Water flow support stand 13 Sealing material 14, 28 Water flow plate 15 Holding rod 20 Sample storage casing (sampler)
21 Sample storage space 22 Pressurizing cylinder chamber 23 Piston 25 Water passage plate holding frame 29 Air supply path 30 Bellofram

Claims (6)

Pressurizing means that pressurizes the sample stored in the internal sample storage space while maintaining the sampling state at the original position through the water pressure plate, and the sample during the water permeability test through the water pressure plate. A sample container having a drainage channel for draining the water that has passed,
A base formed with a water supply path for supporting one surface of the sample with an internal water flow support plate when in close contact with the sample storage container and supplying water to the sample surface through the water flow support plate during a water permeability test Members,
A connecting means for tightly fixing the sample container to the base member so as to be separable;
A water permeation test apparatus comprising a measuring means capable of measuring the amount of water drained through the sample. The pressurizing means includes a piston mechanism that reciprocates in a pressurizing cylinder chamber that is continuously provided in the sample storage space, and presses the water pressure plate by the operation of the piston mechanism, The water permeation test apparatus according to claim 1, wherein the water permeation test is performed with the sample in a triaxial stress state of the same level as the original position. The water permeability test apparatus according to claim 2, wherein the piston mechanism is operated by compressed air supplied from outside. The pressurizing means includes a spring mechanism housed in a pressurization cylinder chamber provided continuously in the sample housing space, and presses the water pressure plate by the operation of the spring mechanism, The water permeation test apparatus according to claim 1, wherein the water permeation test is performed with the sample in a triaxial stress state of the same level as the original position. The water permeability test apparatus according to claim 1, wherein the sample storage container has a blade edge at a lower end, and the sample is taken into the ground space by driving the container from the blade edge onto the ground surface when the sample is collected. 6. The water permeation test apparatus according to claim 5, wherein the sample in the sample storage space is in a triaxial stress state similar to the original position, and the sample is taken into the sample storage space.

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