Loose sandstone rock sample, its preparation method and preparation device

Abstract

The present application discloses a loose sandstone rock sample, a preparation method thereof and a preparation device. The preparation device for the loose sandstone rock sample includes: a base, a guide member, a sleeve and a pressing die. A limiting groove for limiting is formed on the base; the guide member is fixed on the base and extends along the height direction of the base, and is used for guiding in the height direction; the sleeve is matched with the limiting groove and is used for being embedded above the base, and a containing space for preparing the loose sandstone rock sample is formed in the sleeve; the pressing die is sleeved on the guide member and is used for pressing the materials in the sleeve to prepare the loose sandstone rock sample. Based on this preparation device, the loose sandstone can be effectively fixed to make a loose sandstone rock sample, and the safety and reliability of the HMC multi-field coupling test can be improved.

Description

Technical Field

[0001] This application relates to the field of sandstone rock sample preparation, and particularly to a loose sandstone rock sample, a preparation method thereof, and a preparation device therefor. Background Art

[0002] Sandstone is a type of rock mass that is frequently involved in the mining and petroleum industries. In the exploitation of sandstone-type uranium mines and sandstone reservoirs, making sandstone rock samples for HMC (hydrodynamic field-mechanical field-chemical field) multi-field coupling tests is an important means to understand the characteristics of rock formations and determine exploitation technical solutions. At the same time, HMC multi-field coupling tests are also a current research hotspot.

[0003] For dense sandstone, its structure is stable and can withstand relatively large pressures, and the processes of sample preparation and experiments are relatively simple. However, the processes of sample preparation and experiments for loose sandstone are particularly cumbersome. It is difficult to shape loose sandstone during sample preparation. If a gelling material is used to fix the rock sample, the characteristics of the sandstone are directly changed, and the experimental results lack credibility. At both ends of the flow-through section during the experiment of loose sandstone, there are free surfaces. Under the seepage pressure difference, the rock mass undergoes creep, and its loose structure is difficult to withstand the confining pressure, and rock sample fragmentation often occurs. The sandstone particles are continuously lost during the seepage process, and the lost sandstone particles accumulate in large quantities in the pipe network of the experimental instrument, which can cause damage to the instrument at best and accidents such as pipe bursting or injury to experimental personnel at worst. Summary of the Invention

[0004] In view of this, embodiments of this application provide a loose sandstone rock sample, a preparation method thereof, and a preparation device therefor, aiming to effectively fix loose sandstone and improve the safety and reliability of HMC multi-field coupling tests.

[0005] The technical solution of the embodiments of this application is implemented as follows:

[0006] In a first aspect, embodiments of this application provide a preparation device for a loose sandstone rock sample, including:

[0007] A base, on which a limiting groove for limiting is formed;

[0008] A guiding member, fixed on the base and extending along the height direction of the base, for guiding in the height direction;

[0009] A sleeve, cooperating with the limiting groove, for being embedded on the base, and an accommodation space for preparing the loose sandstone rock sample is formed inside the sleeve;

[0010] A pressing die, sleeved on the guiding member, for pressing the material inside the sleeve to prepare the loose sandstone rock sample.

[0011] In some embodiments, the limiting groove is composed of a blind hole formed in the upper surface of the base and a circular boss opposite to the blind hole. The outer diameter of the sleeve matches the inner diameter of the blind hole, the inner diameter of the sleeve matches the outer diameter of the circular boss, and the height of the sleeve is greater than the height of the loose sandstone sample.

[0012] In some embodiments, the pressing die includes:

[0013] A mounting plate, which is provided with a guiding hole for sleeving on the guiding member;

[0014] A cylindrical die, located below the mounting plate, and the outer diameter of the cylindrical die matches the inner diameter of the sleeve;

[0015] Wherein, the cylindrical die has a height mark for indicating that the height of the to-be-formed sample in the sleeve meets the requirements.

[0016] In some embodiments, the height from the height mark to the bottom of the cylindrical die is the difference between the height of the sleeve and the height of the loose sandstone sample minus the height of the circular boss.

[0017] In some embodiments, the top of the cylindrical die is connected to the mounting plate through an extension section with an increasing outer diameter.

[0018] In a second aspect, an embodiment of the present application provides a method for preparing a loose sandstone sample. Based on the preparation device described in the first aspect of the embodiment of the present application, the method includes:

[0019] Sleeving a heat-shrinkable tube on the pressing die, and heating the heat-shrinkable tube to shrink until the heat-shrinkable tube completely wraps the lower end of the pressing die;

[0020] Removing the heat-shrinkable tube after shaping from the pressing die, embedding the heat-shrinkable tube into the sleeve, and then sequentially placing a support mesh and a filter screen into the sleeve;

[0021] After the sleeve is embedded into the base through the limiting groove, pour a set amount of loose sandstone aggregate into the sleeve;

[0022] Control the pressing die to compact the loose sandstone aggregate under the guidance of the guiding member to form a compacted sample with a set height;

[0023] Then, sequentially place a filter screen and a support mesh into the sleeve, and heat the heat-shrinkable tube to shrink until the heat-shrinkable tube completely wraps the upper end of the compacted sample;

[0024] Take out the compacted rock sample wrapped with the thermoplastic tube from the sleeve, and cut off the excess wrapping materials at both ends of the compacted rock sample to obtain the loose sandstone rock sample.

[0025] In some embodiments, the initial diameter of the thermoplastic tube is larger than the diameter of the compacted rock sample, and the diameter after complete shrinkage is smaller than the diameter of the compacted rock sample, so as to apply a certain pressure to the compacted rock sample. The length of the thermoplastic tube is greater than the height of the compacted rock sample.

[0026] In some embodiments, the support mesh is made of a non-metallic material, and the mesh density is at least 20 meshes; the filter screen is made of a non-metallic material, and the mesh density is at least 100 meshes.

[0027] In some embodiments, cutting off the excess wrapping materials at both ends of the compacted rock sample includes:

[0028] Cut off the thermoplastic tube partially wrapped at both ends of the compacted rock sample to provide a seepage channel, and retain an annular wrapping with a length of at least 0.5 cm to provide pressure at both ends.

[0029] In a third aspect, an embodiment of the present application provides a loose sandstone rock sample, which is a loose sandstone rock sample prepared by using the method described in the second aspect of the embodiment of the present application.

[0030] The technical solution provided by the embodiment of the present application, the preparation device of the loose sandstone rock sample includes: a base, a guide member, a sleeve and a pressing die. A limiting groove for limiting is formed on the base; the guide member is fixed on the base and extends along the height direction of the base, and is used for guiding in the height direction; the sleeve is matched with the limiting groove and is used for being embedded on the base. A containing space for preparing the loose sandstone rock sample is formed in the sleeve; the pressing die is sleeved on the guide member and is used for pressing the material in the sleeve to prepare the loose sandstone rock sample. Based on this preparation device, the loose sandstone can be effectively fixed to make a loose sandstone rock sample, improving the safety and reliability of the HMC multi-field coupling test. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of the preparation device of the loose sandstone rock sample according to the embodiment of the present application;

[0032] Figure 2 It is a schematic flow diagram of the preparation method of the loose sandstone rock sample according to the embodiment of the present application;

[0033] Figure 3 It is a schematic structural diagram of the preparation process of the loose sandstone rock sample according to the embodiment of the present application;

[0034] Figure 4 It is a schematic composition structural diagram of the loose sandstone rock sample according to the embodiment of the present application;

[0035] Figure 5 Schematic diagram of the physical structure of the loose sandstone rock sample prepared in the embodiment of the present application.

[0036] Explanation of the reference numerals:

[0037] 1. Pressing die; 2. Guide; 3. Sleeve; 4. Limit groove; 5. Base;

[0038] 6. Support mesh; 7. Filter screen; 8. Thermoplastic tube; 9. Compacted rock sample. Detailed implementation manners

[0039] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on the present application. All other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present application.

[0040] In the description of the present application, reference is made to "some embodiments", which describe a subset of all possible embodiments. However, it can be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0041] In the description of the present application, the terms "first", "second", etc. are only used to distinguish similar objects, and do not represent a specific order for the objects. It can be understood that "first", "second", etc. can be interchanged with a specific order or sequence when permitted, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. Unless otherwise specified, the meaning of "a plurality" is at least two.

[0042] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0043] In this application, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include the first and second features not being in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0044] An embodiment of this application provides a preparation device for loose sandstone rock samples, as Figure 1 shown. The preparation device includes: a base 5, a guide member 2, a sleeve 3, and a pressing die 1. A limiting groove 4 for limiting is formed on the base 5; the guide member 2 is fixed on the base 5 and extends along the height direction of the base 5, and is used for guiding in the height direction; the sleeve 3 is matched with the limiting groove 4 and is used for being embedded above the base 5, and a containing space for preparing loose sandstone rock samples is formed inside the sleeve 3; the pressing die 1 is sleeved on the guide member 2 and is used for pressing the material inside the sleeve 3 to prepare loose sandstone rock samples.

[0045] During actual application, the sleeve 3 can be embedded into the limiting groove 4 of the base 5, and under the guidance of the guide member 2, the pressing die 1 presses the material inside the sleeve 3, thereby preparing loose sandstone rock samples. As a special device for preparing loose sandstone rock samples, this preparation device has high preparation efficiency, good reliability, and can meet the safety and reliability requirements of HMC multi-field coupling tests.

[0046] Exemplarily, as Figure 1 shown, the limiting groove 4 is composed of a blind hole opened on the upper surface of the base 5 and a circular convex platform opposite to the blind hole. The outer diameter of the sleeve 3 matches the inner diameter of the blind hole, the inner diameter of the sleeve 3 matches the outer diameter of the circular convex platform, and the height of the sleeve 3 is greater than the height of the loose sandstone rock sample. In this way, the sleeve 3 can be stably embedded into the limiting groove 4 of the base 5.

[0047] Exemplarily, the pressing die 1 includes: a mounting plate and a cylindrical die. The mounting plate is provided with a guide hole for sleeving on the guide member 2; the cylindrical die is located under the mounting plate, and the outer diameter of the cylindrical die matches the inner diameter of the sleeve 3; wherein, the cylindrical die has a height mark for indicating that the height of the to-be-shaped rock sample inside the sleeve 3 has met the requirements.

[0048] Exemplarily, the height of the height mark from the bottom of the cylindrical mold is the difference between the height of the sleeve 3 and the height of the loose sandstone sample minus the height of the circular boss. In this way, during the pressing process based on the pressing mold 1, based on this height mark, the user can be visually prompted that the height of the sample to be formed meets the requirements.

[0049] Exemplarily, the top of the cylindrical mold is connected to the mounting plate through an extension section with an increasing outer diameter. For example, the extension section can be in the shape of a frustum of a cone. The bottom diameter of the extension section is equal to the diameter of the cylindrical mold, and the top diameter of the extension section is greater than the diameter of the cylindrical mold, so that top limit can be formed when the pressing mold 1 is pressed down.

[0050] Next, a preparation device according to an embodiment of the present application will be exemplarily described in conjunction with an application example.

[0051] In this application example, the specification of the loose sandstone sample to be prepared is a cylinder with a size of 50*50 mm (millimeters), that is, the diameter is 50 mm and the height is 50 mm.

[0052] The cylindrical mold of the pressing mold 1 has the same sample specification. The upper end of the cylindrical mold is a frustum of a cone, the tabletop diameter of which is equal to the sample diameter and is connected to the cylinder, and the bottom diameter is greater than the sample diameter. That is, the diameter of the cylindrical mold is 50 mm, the extension section is a frustum of a cone, the tabletop diameter is 50 mm and is connected to the cylindrical mold, and the top diameter is 70 mm and is connected to the mounting plate.

[0053] The guiding members 2 on the base 5 can be two parallel limiting columns, which are matched with the guiding holes on the mounting plate of the pressing mold 1, so as to ensure that the pressing mold 1 remains horizontal when pressed down.

[0054] The inner diameter of the sleeve 3 is equal to the sample diameter, the height should be greater than the sample height, and the limiting groove 4 on the base 5 should match the specification of the sleeve 3. Therefore, the inner diameter of the sleeve 3 is designed to be 50 mm, the outer diameter is 60 mm, and the height is 60 mm.

[0055] The limiting groove 4 on the base 5 matches the specification of the sleeve 3. Therefore, the outer diameter of the limiting groove 4 is 60 mm, sunken by 5 mm, the inner diameter is 50 mm, and convexed by 2.5 mm (that is, the height of the circular boss is 2.5 mm).

[0056] The cylindrical mold has a height mark to prompt that the height of the pressed sample has reached the requirement. Considering that the height of the sleeve 3 is 60 mm and the height of the convex part of the limiting groove 4 is 2.5 mm, a height mark is made at 7.5 mm from the bottom to the top on the lower end face of the cylindrical mold.

[0057] It should be noted that in addition to pressing when preparing the sample, the pressing mold 1 in the embodiment of the present application also serves as a blow molding mold for the thermoplastic tube 8 to prepare the wrapping material for the sample. For details, reference can be made to the relevant introduction in the method embodiment below.

[0058] The embodiment of the present application also provides a method for preparing a loose sandstone rock sample. Based on the foregoing preparation device, with reference to Figure 2 and Figure 3 , the method includes:

[0059] Step 201, sleeving a heat shrinkable tube on the pressing die, and heating the heat shrinkable tube to shrink until the lower end of the pressing die is completely wrapped by the heat shrinkable tube.

[0060] Exemplarily, a heat shrinkable tube 8 with a suitable specification can be selected according to the specification of the loose sandstone rock sample to be prepared. For example, if the specification of the loose sandstone rock sample is 50*50mm, a heat shrinkable tube 8 with a length of 70mm, a diameter of 70mm, and a diameter ≤ 35mm after complete shrinkage can be sleeved on the pressing die 1, and the heat shrinkable tube 8 is blown and shrunk using a hot air gun until the lower end of the pressing die 1 is completely wrapped by the heat shrinkable tube 8.

[0061] Step 202, removing the heat shrinkable tube after shaping from the pressing die, embedding the heat shrinkable tube into the sleeve, and then sequentially placing a support mesh and a filter screen into the sleeve.

[0062] It can be understood that after removing the heat shrinkable tube 8 after shaping from the pressing die 1 and embedding the heat shrinkable tube 8 into the sleeve 3, the lower end of the heat shrinkable tube 8 is located at the bottom of the sleeve 3, and the open end of the heat shrinkable tube 8 is outside the sleeve 3. One support mesh 6 and one filter screen 7 are successively placed in the sleeve 3, that is, the placed support mesh 6 and filter screen 7 are successively located at the bottom of the heat shrinkable tube 8.

[0063] Step 203, after the sleeve is embedded onto the base through the limiting groove, pour a set amount of loose sandstone aggregate into the sleeve.

[0064] Here, a set amount of loose sandstone aggregate can be poured into the sleeve 3, that is, the raw material for preparing the rock sample is put into the heat shrinkable tube 8 located in the sleeve 3.

[0065] Exemplarily, the above set amount can be determined in combination with a preset rock sample density. In one example, assuming the rock sample density is 1700 kg / m 3 , and the rock sample volume is 98 cm 3 , the weight of the loose sandstone aggregate to be weighed should be 167 g.

[0066] Step 204, controlling the pressing die to compact the loose sandstone aggregate under the guidance of the guiding member to form a compacted rock sample with a set height.

[0067] In one example, a height mark is made at 7.5 mm from the bottom to the top on the lower end face of the cylindrical die. In this way, when the upper end face of the sleeve 3 is aligned with this height mark, it can be determined that the loose sandstone in the sleeve 3 has been compacted, and a compacted rock sample 9 with a set height (i.e., 60 mm) is obtained.

[0068] Step 205: Then, place a filter screen and a supporting mesh in the sleeve in sequence, and heat-shrink the heat-shrinkable tube until the upper end of the compacted rock sample is completely wrapped by the heat-shrinkable tube.

[0069] Here, remove the pressure-applying die 1, place one filter screen 7 and one supporting mesh 6 in the sleeve 3 successively, and use a hot air gun to blow the heat-shrinkable tube 8 until the upper end of the compacted rock sample 9 is completely wrapped.

[0070] Step 206: Take out the compacted rock sample wrapped with the heat-shrinkable tube from the sleeve, and cut off the excess wrapping materials at both ends of the compacted rock sample to obtain a loose sandstone rock sample.

[0071] Exemplarily, cutting off the excess wrapping materials at both ends of the compacted rock sample 9 includes: cutting off part of the heat-shrinkable tube 8 wrapped at both ends of the compacted rock sample 9 to provide a seepage channel, and retaining an annular wrapping with a length of at least 0.5 cm to provide pressure at both ends.

[0072] Exemplarily, the initial diameter of the heat-shrinkable tube 8 is larger than the diameter of the compacted rock sample 9, and the diameter after complete shrinkage is smaller than the diameter of the compacted rock sample 9 to apply a certain pressure to the compacted rock sample 9. The length of the heat-shrinkable tube 8 is greater than the height of the compacted rock sample 9 (i.e., the height of the loose sandstone rock sample).

[0073] In practical applications, the scenario of the HMC multi-field coupling test is: a liquid-solid two-phase seepage and its chemical reaction test with sandstone as the porous medium, the over-flow pressure difference is 1 MPa, and the initial solution is 3% dilute sulfuric acid. Exemplarily, the material of the heat-shrinkable tube 8 can be polyethylene and does not react with dilute sulfuric acid.

[0074] Exemplarily, the supporting mesh 6 is made of a non-metallic material, and the mesh density is at least 20 meshes; the filter screen 7 is made of a non-metallic material, and the mesh density is at least 100 meshes.

[0075] In one example, the material of the supporting mesh 6 can be a non-metallic hard material. The material does not participate in the chemical reaction in the HMC multi-field coupling test, can withstand a certain pressure, and the diameter is equivalent to that of the rock sample. Its mesh density should be at least 20 meshes to fix the shape of the rock sample and prevent creep. Therefore, the material of the supporting mesh 6 is designed as a hard carbon fiber mesh with a diameter of 50 mm and a mesh density of 20 meshes, which can effectively resist the creep of the rock sample and does not react with dilute sulfuric acid.

[0076] In one example, the material of the filter screen 7 is a non-metallic material. The material does not participate in the chemical reaction in the HMC multi-field coupling test, the diameter is equivalent to that of the rock sample, its mesh density should be not less than 100 meshes and can intercept more than 95% of the sandstone particles to collect the exuded particles and prevent instrument blockage. Therefore, the material of the filter screen 7 is designed as a polyester fiber filter cloth with a diameter of 50 mm. According to the particle size distribution characteristics of the rock sample, its mesh density is 500 meshes and it does not react with dilute sulfuric acid.

[0077] The embodiment of the present application also provides a loose sandstone rock sample, which is a loose sandstone rock sample prepared by using the preparation method described in the embodiment of the present application.

[0078] Exemplarily, as Figure 4 shown, the composition of the loose sandstone rock sample prepared in the embodiment of the present application includes:

[0079] Support mesh 6, the material of which is a non-metallic hard material, and the material does not participate in the chemical reaction in the HMC multi-field coupling test, can withstand a certain pressure, the diameter is equivalent to that of the rock sample, and the mesh density should be at least 20 meshes to fix the shape of the rock sample and prevent creep. Therefore, it is designed that the material of the support mesh 6 is a hard carbon fiber mesh, the diameter is 50 mm, and the mesh density is 20 meshes, which can effectively resist the creep of the rock sample and does not react with dilute sulfuric acid;

[0080] Fine-mesh filter screen 7, the material of which is a non-metallic material, and the material does not participate in the chemical reaction in the HMC multi-field coupling test, the diameter is equivalent to that of the rock sample, and the mesh density should be not less than 100 meshes and can intercept more than 95% of the sandstone particles to collect the exuded particles and prevent the instrument from being blocked. Therefore, it is designed that the material of the fine-mesh filter screen 7 is a polyester fiber filter cloth, the diameter is 50 mm, and according to the particle size distribution characteristics of the rock sample, the mesh density is 500 meshes and does not react with dilute sulfuric acid;

[0081] Thermoplastic tube 8, the initial diameter of which should be larger than the diameter of the rock sample, and the diameter after complete shrinkage should be smaller than the diameter of the rock sample to apply a certain pressure to the rock sample, and the length of the thermoplastic tube 8 taken should be longer than the length of the rock sample. Therefore, the thermoplastic tube 8 with a specification of a diameter of 70 mm and a diameter ≤ 35 mm after complete shrinkage is used, and its material is polyethylene and does not react with dilute sulfuric acid;

[0082] Compacted rock sample 9, the amount of loose sandstone weighed should be combined with the preset density of the rock sample to determine the weight of the sandstone weighed. Therefore, in the embodiment, the volume of the rock sample is designed to be 98 cm 3 , and the weight of the loose sandstone to be weighed should be 167 g, Figure 4 The shown is the effect after pressing and forming.

[0083] In one example, the entity of the loose sandstone rock sample prepared in the embodiment of the present application is as Figure 5 shown, and the entity structure of the loose sandstone rock sample is:

[0084] Compacted rock sample 9, which is 167 g of loose sandstone particles and is formed into a cylindrical rock sample by a preparation device;

[0085] The lateral shaping material is a lateral wrapping formed by blow molding and shrinking of a 70 mm × 70 mm polyethylene thermoplastic tube 8;

[0086] The two-end wrapping is formed by a 20-mesh carbon fiber rigid support mesh sheet 6 wrapped by a thermoplastic tube 8.

[0087] The filtering material is a 500-mesh polyester fiber fine mesh filter screen that can intercept more than 95% of the main particles.

[0088] It should be noted that conducting a multi-field coupling test of the water flow field - mechanical field - chemical field (HMC) on engineering rock masses to understand their rock mass characteristics is a current research hotspot. At present, there is still a lack of a preparation method and device for loose sandstone rock samples dedicated to HMC multi-field coupling experiments. The loose sandstone rock samples prepared in the embodiments of this application can maintain their shape without a gelling material, can effectively transfer confining pressure on the side, can withstand a large seepage pressure difference at both ends, can effectively retain sandstone particles during the HMC multi-field coupling test, are convenient for collection and weighing, and can prevent instrument blockage. At the same time, materials such as the thermoplastic tube 8, the filter screen 7, and the support mesh sheet 6 are all non-metallic, which is convenient for directly carrying out detections such as nuclear magnetic resonance in the experiment and does not participate in the chemical reactions in the test; the preparation device involved in the embodiments of this application can quickly prepare loose sandstone rock samples, ensuring the consistency and quality of the rock samples. It can provide effective support for the HMC multi-field coupling test of loose sandstone.

[0089] It should be noted that: among the technical solutions described in the embodiments of this application, they can be combined arbitrarily without conflict.

[0090] The above is only the specific implementation manner of this application, but the protection scope of this application is not limited thereto. Any person skilled in the art within the technical scope disclosed in this application can easily think of changes or substitutions, which should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claimed rights.

Claims

1. A preparation method of loose sandstone rock samples, based on a preparation device for loose sandstone rock samples, characterized in that, The preparation device includes: A base on which a limiting groove for positioning is formed; A guiding member fixed on the base and extending along the height direction of the base, for guiding in the height direction; A sleeve, which cooperates with the limiting groove and is used to be embedded above the base. An accommodating space for preparing the loose sandstone rock sample is formed inside the sleeve; A pressing die, sleeved on the guiding member, for pressing the material inside the sleeve to prepare the loose sandstone rock sample; The method includes: Sleeving a heat shrinkable tube on the pressing die and heating the heat shrinkable tube to shrink until the heat shrinkable tube completely wraps the lower end of the pressing die; Removing the heat shrinkable tube after shaping from the pressing die, embedding the heat shrinkable tube into the sleeve, and then sequentially placing a support mesh and a filter screen into the sleeve; After the sleeve is embedded above the base through the limiting groove, pouring a set amount of loose sandstone aggregate into the sleeve; Controlling the pressing die to compact the loose sandstone aggregate under the guidance of the guiding member to form a compacted rock sample with a set height; Then sequentially placing a filter screen and a support mesh into the sleeve, and heating the heat shrinkable tube to shrink until the heat shrinkable tube completely wraps the upper end of the compacted rock sample; Taking out the compacted rock sample wrapped with the heat shrinkable tube from the sleeve and cutting off the excess wrapping material at both ends of the compacted rock sample to obtain the loose sandstone rock sample.

2. The method according to claim 1, characterized in that, The limiting groove is composed of a blind hole opened on the upper surface of the base and a circular boss opposite to the blind hole. The outer diameter of the sleeve matches the inner diameter of the blind hole, the inner diameter of the sleeve matches the outer diameter of the circular boss, and the height of the sleeve is greater than the height of the loose sandstone rock sample.

3. The method according to claim 2, wherein The pressing die includes: A mounting plate on which a guiding hole for sleeving on the guiding member is opened; A cylindrical die located below the mounting plate, and the outer diameter of the cylindrical die matches the inner diameter of the sleeve; Wherein, there is a height mark on the cylindrical die for indicating that the height of the rock sample to be formed in the sleeve has met the requirements.

4. The method according to claim 3, characterized in that The height of the height mark from the bottom of the cylindrical die is the difference between the height of the sleeve and the height of the loose sandstone rock sample minus the height of the circular boss.

5. The method according to claim 3, characterized in that The top of the cylindrical die is connected to the mounting plate through an extension section with an increasing outer diameter.

6. The method according to claim 1, characterized in that The initial diameter of the heat shrinkable tube is greater than the diameter of the compacted rock sample, and the diameter after complete shrinkage is smaller than the diameter of the compacted rock sample, so as to apply a certain pressure to the compacted rock sample, and the length of the heat shrinkable tube is greater than the height of the compacted rock sample.

7. The method according to claim 1, characterized in that The support mesh is made of non-metallic material, and the mesh density is at least 20 meshes; The filter screen is made of non-metallic material, and the mesh density is at least 100 meshes.

8. The method according to claim 1, characterized in that, The cutting off the excess wrapping material at both ends of the compacted rock sample includes: Cut off the thermoplastic tubes wrapped around both ends of the compacted rock sample to provide a seepage channel, and retain an annular wrap with a length of at least 0.5 cm to provide pressure at both ends.

Images