JP2012018015A - Bedrock sample permeability testing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bedrock sample permeability testing method realizing an implementation of various measurements by performing a permeability test under a perfect three principal stresses condition with a true triaxial testing device using a cubic bedrock sample.SOLUTION: A permeability test is carried out in a following configuration. Plurality of surfaces of a bedrock sample 1 having a cubic shape are pasted with water guide plates 2, the guide plates 2 each being provided with groove 2a formed thereon on a side abutting on the surface of the bedrock sample 1. Then the entire bedrock sample 1 having the water guide plates 2 being pasted on the surfaces thereof is coated with a coating member 3 having waterproof property and elasticity. To the bedrock sample 1 covered with the coating member 3, three principal stresses are applied by pressing pressure plates 11A and 11B abutting on the coating member 3 on respective surfaces of the cubic shape, and at the same time, water is supplied to the groove 2a of the water guide plate 2 on a water injection side in a water permeation direction via a water injection pipe provided through the coating member 3. Also the water having reached the water guide plate 2 on a drainage side in the water permeation direction is collected in the groove 2a and drained via a drainage pipe provided through the coating member 3.

Description

  The present invention relates to a rock sample permeability test method. More specifically, the present invention relates to a rock sample permeability test method suitable for application to a permeability test under three principal stress conditions using a cubic rock sample.

  In the present invention, a test carried out under the condition in which three principal stresses in two horizontal orthogonal directions (X-axis direction and Y-axis direction) and vertical direction (Z-axis direction) are applied independently is true triaxial. An apparatus capable of performing the true triaxial test is called a true triaxial test apparatus. In addition, since a cubic rock sample is generally used in the conventional triaxial tests, the description of the present invention assumes that the shape of the rock sample is a cube, but the scope of the present invention is as follows. This does not exclude the case of using a rectangular parallelepiped rock sample.

  For example, in the design of structures in underground rock masses such as deep underground tunnels and radioactive waste disposal facilities, it is important to understand the characteristics of rock masses such as thermal characteristics, hydraulic characteristics, mechanical characteristics, etc. Understanding physical properties is important.

  As a conventional permeability test method for a rock sample, for example, as shown in FIG. 4, a large bedrock that pressurizes the top and bottom and two sides of a cube-shaped rock sample S installed on a pedestal 101 via a pressurizing mechanism. In the test apparatus, the surface of the rock sample S installed on the pedestal 101 excluding the water-permeable surface is covered with a rubber jacket 102, and water-tightness is provided by pressure plates 103, 104, and 105 having a water flow surface 108 formed on the bottom surface, side surface, and top surface. (Patent Document 1). FIG. 4 shows the component structure of the water stop structure when the rock sample S is tested for water permeability in the vertical direction. In the figure, reference numeral 106 denotes a filter paper, reference numeral 107 denotes a flange presser for fixing the upper periphery and the lower periphery of the rubber jacket 102, and reference numerals (1) to (9) in the figure indicate assembling procedures of the respective parts. Yes.

JP 2001-349813 A

  However, in the water permeation test method of Patent Document 1, two surfaces in the water permeation direction (the upper surface and the lower surface in the example shown in FIG. 4) are not covered with the rubber jacket 102, and therefore the dimensions in the water permeation direction are reduced by pressing in the water permeation direction. When the rubber jacket 102 is bent, the water stop effect is lost particularly at the end of the rubber jacket 102. In addition, when pressure is applied from the lower surface pressure plate 103 and the upper surface pressure plate 105, the flange presser 107 and the edge of the side surface pressure plate 104 collide with each other, so in practice, almost no pressure can be applied in the direction of water permeability. However, the substance is only suppressed, and it is difficult to say that it is a water permeability test under the three principal stress conditions. At least, the pressure in the direction of water permeability cannot be freely set to a desired level. Therefore, it is difficult to say that a water permeability test can be performed under the complete three principal stress conditions.

  Moreover, in the water permeability test method of patent document 1, since the temperature of the rock sample S cannot be controlled, the thermal characteristics of the rock cannot be grasped. Therefore, there is a problem that sufficient data cannot be provided for grasping the physical properties of the rock.

  In other words, in order to grasp the physical properties of the rock mass, it is necessary to grasp the permeability and mechanical properties of the rock mass. In order to understand these properties, a complete triaxial test system using a cubic rock mass sample is used. However, there is no test method / apparatus that satisfies these test requirements, although it is necessary to conduct various measurements by conducting a water permeability test under the three principal stress conditions. In addition, in order to fully understand the physical properties of the rock mass, it is necessary to grasp the thermal properties, hydraulic conductivity, and mechanical properties of the rock mass. Although it is necessary to conduct various measurements by conducting a permeability test while controlling the temperature of a rock sample under the complete three principal stress conditions using the equipment, there is no test method / apparatus that satisfies all these test requirements.

  Therefore, an object of the present invention is to provide a rock sample permeability test method capable of performing various measurements by performing a permeability test under a complete three principal stress condition using a cubic rock sample. Furthermore, the present invention provides a rock sample permeability test method capable of performing various measurements by performing a permeability test while controlling the temperature of the rock sample under a complete three principal stress condition using a cubic rock sample. With the goal.

  In order to achieve this object, the rock sample permeability test method according to claim 1 is a cubic rock sample in a state in which a water guide plate having grooves formed on the side contacting the surface of the rock sample is attached to a plurality of surfaces. Is covered with a covering member having waterproofness and elasticity, and is applied to the rock sample covered with the covering member while applying three principal stresses by a pressure plate abutting the covering member on each surface of the cubic shape. Water is supplied to the groove of the water guide plate on the water injection side in the water permeable direction through the water injection pipe provided through the member, and the water reaching the water guide plate on the drain side in the water permeable direction is collected by the groove to cover the covering member. The water permeation test is performed by draining through drainage pipes that are provided through.

  Therefore, according to the rock sample permeability test method, the entire rock sample with the water guide plates attached to a plurality of surfaces is covered with a covering member having waterproofness and elasticity to perform a triaxial test. Therefore, the water stop effect is ensured in any direction, and a desired pressure (load) can be applied in the water permeation direction.

  According to a second aspect of the present invention, in the rock sample water permeability test method according to the first aspect, the covering member is made of silicon rubber. In this case, waterproofness and elasticity required as a covering member in the present invention are surely ensured.

  According to a third aspect of the present invention, in the rock sample permeability test method according to the first aspect, a heating part is provided in the pressure plate to which the three principal stresses are applied, and the temperature of the rock sample is controlled by the heating part. ing. In this case, the water permeability test can be performed while controlling the temperature of the rock sample.

  The invention according to claim 4 is the rock sample permeability test method according to claim 3, wherein the heating part is a rubber heater. In this case, the heating unit can be easily accommodated in the pressure plate.

  According to the rock sample permeability test method according to claim 1, the water-stopping effect is ensured in any direction, and a desired pressure (load) is applied in the direction of permeability, and the water permeability is completely under the three principal stress conditions. Since the test can be performed, data useful for grasping the true physical properties of the rock mass can be provided, and the usefulness and reliability of the rock sample permeability test can be improved.

  According to the rock sample permeability test method according to claim 2, since the permeability test can be performed while controlling the temperature of the rock sample, data useful for sufficiently grasping the true physical properties of the rock is provided. It is possible to improve the usefulness and reliability of the rock sample permeability test.

It is a figure explaining the bedrock sample permeability test method of the present invention. (A) is a vertical sectional view of a triaxial test apparatus according to an embodiment of the present invention. (B) is a vertical sectional view of a specimen used in the present invention. It is a horizontal sectional view of the triaxial testing device of an embodiment which carries out the rock sample permeability test method of the present invention. It is a figure which shows the structure of the water guide plate used with the rock sample water permeability test method of this invention. It is a disassembled perspective view which shows the components structure and assembly procedure of the conventional water-permeable test apparatus.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 3 show an example of an embodiment of the rock sample permeability test method of the present invention. In the rock sample permeability test method of the present invention, at least the entirety of the cubic rock sample 1 in a state where the water guide plate 2 having grooves 2a formed on the side contacting the surface of the rock sample 1 is attached to a plurality of surfaces is waterproofed. Three main stresses are applied to the rock sample 1 covered with the covering member 3 having the property and elasticity by the pressure plates 11A and 11B that are in contact with the covering member 3 on each surface of the cubic shape. However, water is supplied to the groove 2a of the water guide plate 2 on the water injection side in the water permeable direction through the water injection pipe provided through the covering member 3, and the water that has reached the water guide plate 2 on the drain side in the water permeable direction is grooved. The water permeation test is carried out by draining through a drainage pipe collected through 2a and provided through the covering member 3.

  The rock sample 1 is formed into a cube in the same manner as in a normal triaxial test. And the water guide plate 2 is affixed on each surface (namely, six surfaces) of the cube-shaped rock sample 1 as shown in FIG.1 (B). In FIG. 1 and FIG. 2, the cross-sectional thicknesses of the water guide plate 2 and the covering member 3 are made thicker than the actual relative relationship with other members / parts in consideration of making the component configuration easy to understand. it's shown.

  In the present embodiment, a stainless mesh 5 is interposed between each surface of the rock sample 1 and the water guide plate 2 in order to spread the water supplied from the water guide plate 2 over the entire surface of the rock sample 1. However, the stainless steel mesh 5 is not an essential component of the present invention, and the stainless steel mesh 5 may not be interposed.

  As shown in FIG. 3, a groove 2 a is formed on the surface of the water guide plate 2 on the side in contact with the rock sample 1 with the stainless steel mesh 5 interposed therebetween. The groove 2a is formed in a mesh shape in the present embodiment, but is not limited to this, and may be a plurality of parallel lines, for example. Moreover, it is desirable that the groove 2 a is formed over the entire surface of the water guide plate 2.

  The water guide plate 2 is formed of a material having such a rigidity that the groove 2a is not crushed even when stress as applied to the rock sample 1 is applied. Specifically, for example, it is formed of aluminum or stainless steel.

  The water guide plate 2 is formed to a thickness of about 1 [mm], for example. The groove 2a is formed, for example, with a width of about 1 [mm] and a depth of about 0.5 [mm]. Further, the interval between the grooves 2a is appropriately set in consideration of the size and water permeability of the rock sample 1.

  Further, the water guide plate 2 is used for supplying water for allowing the rock sample 1 to permeate into the groove 2a, or for collecting and draining the water permeated through the rock sample 1 via the groove 2a. A pipe insertion part 2b is provided which is open at the end and into which a water injection / drainage pipe (not shown) is inserted and which communicates with any part of the groove 2a. The distal end portion of the water injection / drainage pipe is inserted into the pipe insertion portion 2b and fixed by, for example, an adhesive.

  The entire rock sample 1 with the water guide plate 2 attached to each surface, in other words, the entire rock sample 1 including the water guide plate 2 together with the covering member 3 having at least waterproofness and elasticity. Cover without gaps. Further, when the rock sample 1 is heated to control the temperature of the rock sample 1, the covering member 3 needs to further have heat resistance against an assumed temperature in addition to waterproofness and elasticity.

  Note that the elastic modulus (hardness) of the covering member 3 is appropriately selected in consideration of the magnitude of the principal stress to be applied and the assumed thickness. In addition, when covering the whole with the covering member 3, a sensor injection cable affixed to the surface of the water injection / drainage pipe or the rock sample 1 whose tip is inserted into the pipe insertion part 2 b of the water guide plate 2 is provided. It is made not to be buried in the covering member 3 excessively.

  In this embodiment, since it is appropriate in that it has a certain heat resistance in addition to waterproofness and moderate elasticity, it is covered with silicon rubber 3 without any gap. The covering with the silicon rubber 3 is performed, for example, by applying and solidifying the liquid silicon rubber 3 on the entire surface with the water guide plate 2 attached to each surface of the rock sample 1. The thickness of the silicon rubber 3 is, for example, about 3 to 4 [mm]. Further, it is desirable that the thickness of the silicon rubber 3 does not vary greatly depending on the location within the range where the water guide plate 2 exists.

  And three principal stress is added with respect to the rock mass sample 1 which covered the whole with the coating | coated member 3 without gap in the state which affixed the water guide plate 2 on each surface of the cube shape. At this time, since the water stopping conditions in the entire surface (in other words, three directions) are ensured, the water permeability test can be performed by freely setting the loading in the three directions to a desired level. That is, the permeability test of the rock sample 1 under the complete three principal stress conditions can be performed. In the following description, what is formed by covering the entire rock sample 1 and the water guide plate 2 attached to the rock sample 1 with the covering member 3 without a gap is also referred to as a test body 4.

  In this embodiment, the triaxial test apparatus 10 shown in FIG.1 and FIG.2 is used as an apparatus which performs the water permeability test of the test body 4 shape | molded as mentioned above. In FIG. 1 and FIG. 2, the bolts and screws that connect the components are not shown in order to facilitate understanding of the component configuration. Further, in FIG. 1A, a vertical section at different positions of the apparatus 10 is shown on the left side (symbol IA) and the right side (symbol IB) of the alternate long and short dash line (symbol I) in the figure (symbol IA side: A longitudinal section at a position closer to the side surface than the center position, symbol IB side: a longitudinal section at the center position).

  The triaxial testing apparatus 10 includes a total of four horizontal pressure plates 11A that abut against each of the side surfaces of the test body 4 and independently apply stress, and a vertical direction press that abuts against the lower surface of the test body 4 and applies stress. The pressure plate 11B and a total of four horizontal cylinders 12 that act as guides for the horizontal reciprocation of the pressure plate 11A, assuming that the pressure plate 11A is a piston. That is, each horizontal pressure plate 11A is slidably accommodated in each horizontal cylinder 12 and guided so as to be able to reciprocate in the horizontal direction.

  Further, an upper surface fixing plate 14 that comes into contact with the upper surface is provided on the upper surface of the test body 4.

  In this embodiment, a guide pin 13A is attached to each horizontal pressure plate 11A so as to protrude from the surface opposite to the test body 4 (ie, the outer surface). In the present embodiment, a total of four guide pins 13A are attached at positions near each corner of the rectangular horizontal pressure plate 11A. Further, a guide hole 13B is provided inside each horizontal cylinder 12 so as to slidably accommodate and guide the protruding portion of the guide pin 13A on the surface facing the horizontal pressure plate 11A. As a result, the horizontal pressure plate 11A is prevented from tilting when reciprocating, and stress is evenly applied to the entire side surface of the test body 4.

  The triaxial test apparatus 10 is attached to the frame 15 having a horizontal cross-section rectangle and constituting four side walls of the apparatus 10 to fix and hold the four horizontal cylinders 12, and the upper end of the frame 15. And a rectangular upper plate 16 that constitutes the top plate of the apparatus 10 and fixes and holds the upper surface fixing plate 14, and a rectangular lower plate 17 that is attached to the lower end of the frame 15 and constitutes the bottom plate of the apparatus 10. . The horizontal cylinder 12 is attached to the frame body 15 by screws and the upper surface fixing plate 14 is attached to the upper plate 16 by screws.

  The frame 15, the upper plate 16 and the lower plate 17 are combined to surround the test body 4, the horizontal pressure plate 11 </ b> A and the horizontal cylinder 12, the vertical pressure plate 11 </ b> B, and the upper surface fixing plate 14. The entire device 10 is formed in a rectangular parallelepiped shape. Note that the triaxial test apparatus 10 of the present embodiment has an installation leg 21 attached to the lower surface of the lower plate 17.

  Here, in the present invention, sensors such as strain gauges may be appropriately attached to the surface of the rock sample 1 in accordance with the purpose of the water permeability test method. And when attaching sensors, the cable of the said sensors penetrates the coating | coated member 3, and the channel | path (through-hole) for taking out the said cable from the triaxial test apparatus 10 is provided in the frame 15, for example You may do it. More specifically, for example, a groove may be provided on the upper end surface of the frame body 15 to form a cable outlet passage between the lower surface of the upper plate 16.

  On the upper surface of the lower plate 17 (that is, the surface facing the vertical pressure plate 11B), a concave portion that acts as a guide (in other words, a cylinder) for vertical reciprocation of the pressure plate 11B, assuming that the vertical pressure plate 11B is a piston. 17a is formed. That is, the vertical pressure plate 11B is slidably accommodated and guided in the recess 17a of the lower plate, and is configured to be able to reciprocate in the vertical direction.

  The frame 15, the upper plate 16, and the lower plate 17 exhibit a function as a support housing that resists a reaction force when stress is applied to the test body 4, and the frame 15 and the lower plate 17. Are firmly connected and fixed by bolts and screws, and after receiving the test body 4 in this state, the frame body 15 and the upper plate 16 are firmly connected and fixed by bolts and screws.

  The horizontal reciprocating motion of each horizontal pressure plate 11A opposes the side surface of the test body 4 of the horizontal cylinder 12 and the through hole 15a penetrating each surface (in other words, each side wall) of the frame 15 in the horizontal direction. It is controlled by injecting and discharging a fluid such as water by a pressure intensifier (not shown) through a through hole 12a penetrating the surface in the horizontal direction. And the magnitude | size of the stress added to the test body 4 by the horizontal direction pressurization board 11A is controlled by adjusting the injection pressure of the said fluid of a pressure booster. The through holes 15a are provided in each of the four side walls of the frame 15 (two in this embodiment), and the four horizontal pressure plates 11A are controlled independently, The magnitude of the stress applied to the side is controlled independently.

  In addition, the vertical reciprocating motion of the vertical pressure plate 11B is controlled by injecting and discharging a fluid such as water by a pressure intensifier (not shown) through a through hole 17b penetrating the lower plate 17 in the vertical direction. The And the magnitude | size of the pressure added to the test body 4 by the vertical direction pressurization board 11B is controlled by adjusting the injection pressure of the said fluid of a pressure booster.

  The triaxial test apparatus 10 of the present invention penetrates the frame 15 and the horizontal cylinder 12 in the horizontal direction and is inserted into the horizontal pressure plate 11A and fixed to the horizontal pressure plate 11A, and the frame 15 and the horizontal direction. A pipe 20a slidably provided with respect to the cylinder 12 and the lower plate 17 are penetrated in the vertical direction and inserted into the vertical pressure plate 11B to be fixed to the vertical pressure plate 11B and to the lower plate 17. It has a tube 20b that is slidably provided, and a gap sensor (not shown) that is attached to the outside of the triaxial test apparatus 10 and measures the amount of displacement of each tube 20a, 20b. And the displacement amount of each horizontal direction pressurization board 11A and the vertical direction pressurization board 11B is measured by the said gap sensor as a displacement amount of each pipe | tube 20a, 20b. Thereby, since the pressure applied to the test body 4 is controlled by the pressure intensifier and the displacement amount of each pressurizing plate 11A, 11B is measured, the accurate stress applied to the rock sample 1 can be grasped.

  In addition, the triaxial test apparatus 10 includes a pressure sensor 18 and a gap sensor 19 that are fixed to the upper plate 16 and have a tip surface that abuts against the upper surface of the test body 4. The pressure sensor 18 and the gap sensor 19 directly measure the pressure on the upper surface of the test body 4 (in other words, the pressure applied to the upper surface) and the displacement of the upper surface of the test body 4.

  With the above-described configuration, according to the triaxial test apparatus 10 of the present embodiment, the horizontal specimen 2 in the horizontal direction (X axis direction, Y direction) is applied to the rock sample 1 in the test body 4 by the horizontal pressure plates 11A and the vertical pressure plates 11B. Three principal stresses in the axial direction) and the vertical direction (Z-axis direction) can be applied independently, and a true triaxial test can be performed.

  The triaxial test apparatus 10 of the present embodiment further includes a heating unit 20 for controlling the temperature of the rock sample 1 under test. In the present embodiment, as the heating unit 20, specifically, rubber heaters are provided inside each horizontal pressure plate 11 </ b> A, inside the vertical pressure plate 11 </ b> B, and between the upper surface fixing plate 14 and the upper plate 16. .

  In the present embodiment, the horizontal pressure plate 11A and the vertical pressure plate 11B are divided into two in the direction of the plate surface, and a recess is formed on one side, and the rubber heater 20 is stored in the recess. Further, a recess is formed on the contact side of the upper surface fixing plate 14 with the upper plate 16, and the rubber heater 20 is stored in the recess.

  The tube 20a is inserted into the horizontal pressure plate 11A to reach the storage space for the rubber heater 20, and the tube 20b is inserted into the vertical pressure plate 11B to enter the storage space for the rubber heater 20. Has reached. And the power line of each rubber heater 20 is pulled out to the outside of the triaxial testing apparatus 10 via either the pipes 20a, 20b or the through hole 16a penetrating the upper plate 16 in the vertical direction. Connected to a power supply device (not shown). And the temperature of the rubber heater 20 is controlled by operation of the said external power supply device.

  By providing the heating unit 20, according to the triaxial test apparatus 10 of the present embodiment, a water permeability test can be performed while controlling the temperature of the rock sample 1.

  When grasping the temperature distribution of the rock sample 1, temperature measurement sensors such as thermocouples are attached to a plurality of locations on the surface of the rock sample 1. And the cable of the said temperature measurement sensor is taken out outside the apparatus 10 through the cable extraction path | route for taking out the cables of sensors, such as the above-mentioned strain gauge, from the triaxial test apparatus 10. FIG.

  According to the rock sample permeability test method of the present invention configured as described above, a water stop effect is ensured in any direction, and the desired three-dimensional stress is applied by adding a desired pressure (load) in the direction of permeability. Since the permeability test can be performed under conditions, it is possible to provide useful data for grasping the true physical properties of the rock mass, and to improve the usefulness and reliability of the rock sample permeability test. . In addition, since the permeability test can be performed while controlling the temperature of the rock sample, it is possible to provide data useful for sufficiently grasping the true physical properties of the rock sample, and the usefulness and reliability of the rock sample permeability test can be provided. Improvements can be made.

  In addition, although the above-mentioned form is an example of the suitable form of this invention, it is not limited to this, A various deformation | transformation implementation is possible in the range which does not deviate from the summary of this invention. For example, in the present embodiment, the triaxial test apparatus 10 includes the heating unit 20, but the heating unit 20 is not an essential configuration in the present invention. For example, when conducting a permeability test under the complete three principal stress conditions to understand the permeability and mechanical properties of the rock mass, in other words, it is not necessary to grasp the thermal properties of the rock mass and control the temperature of the rock sample 1 If it is not necessary, the triaxial testing apparatus 10 that does not have the heating unit 20 may be used.

  In the present embodiment, a rubber heater is used as the heating unit 20. However, as the heating unit 20 of the present invention, as long as heat can be supplied to the pressure plates 11 </ b> A and 11 </ b> B and the upper surface fixing plate 14. Any thing is good. That is, the heater is not limited to a rubber heater, or a flow path is formed in each of the pressure plates 11A and 11B and the upper surface fixing plate 14 so that the temperature-controlled fluid flows in the flow path. Also good.

  Moreover, in this embodiment, although the water guide plate 2 is affixed on each surface (namely, six surfaces) of the rock sample 1, the water guide plate 2 is the water injection side of the rock sample 1 based on the permeation direction of a test object. You may make it stick on only two surfaces, the surface of this, and the surface of a waste_water | drain side.

DESCRIPTION OF SYMBOLS 1 Rock sample 2 Water guide plate 2a Groove 3 Coating | coated member 11A Horizontal direction pressure plate 11B Vertical direction pressure plate

Claims (4)

  The cubic rock sample in a state in which a water guide plate having grooves formed on the side in contact with the surface of the rock sample is attached to a plurality of surfaces is covered with a covering member having waterproofness and elasticity, and the covering Permeability direction through the water injection pipe provided through the covering member while applying three principal stresses to the rock sample covered by the member by a pressure plate abutting the covering member on each surface of the cubic shape Water is supplied to the groove of the water guide plate on the water injection side, and the water that has reached the water guide plate on the drain side in the direction of water permeability is collected by the groove and passed through the drainage pipe provided through the covering member. The rock sample permeability test method is characterized by draining and conducting a permeability test.   The rock sample permeability test method according to claim 1, wherein the covering member is silicon rubber.   The rock sample permeability test method according to claim 1, wherein a heating part is provided in the pressure plate to which the three principal stresses are applied, and the temperature of the rock sample is controlled by the heating part. The rock sample permeability test method according to claim 3, wherein the heating section is a rubber heater.

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