Preparation method of fractured porous medium

Abstract

The invention relates to a preparation method of a fractured porous medium, which comprises the following steps: filling a container with glass beads to form a medium sample, in the filling process, selecting one of wood veneers, rock salt and gypsum cement as required to prepare a fractured sample, and placing the fractured sample in the medium sample; putting the container with the medium sample into a heating furnace, heating the container from normal temperature to 700 DEG C, maintaining the temperature at 700 DEG C for 35 minutes, then cooling the container to 600 DEG C, maintaining the temperature at 600 DEG C for 20 minutes, stopping heating, cooling the container to normal temperature, and taking out the medium sample with fissure sample residues from the container; and removing fissure-shaped sample residues in the medium sample by water flooding. According to the preparation method provided by the invention, the shape and size of the fracture can be controlled, so that various fracture styles in a porous medium in reality can be simulated, the structural characteristics or stress characteristics under various fracture conditions can be conveniently researched, and the accuracy and reliability of a rock stratum mechanics experiment research result are improved.

Description

Technical Field

[0001] This application relates to the technical field of fractured porous media, and particularly to a preparation method of fractured porous media. Background Art

[0002] Due to the long-term deposition and superposition of weathering and fluvial erosion, rock and soil will form a complex structure containing fractured porous media. The formation of completely weathered rock and soil will contain a large number of irregular fractures, which will greatly affect its own stability and safety in actual engineering, and geological disasters caused by the instability of its own structure are likely to occur.

[0003] Most of the media prepared in existing test models are fractured media, and the problems of consolidation of porous media and preparation of fractures have not been effectively solved. Therefore, there is an urgent need for a preparation method of fractured porous media to construct a test model that conforms to the actual situation to verify the reliability of simulation. Summary of the Invention

[0004] Based on this, it is necessary to provide a preparation method of fractured porous media to overcome the defects mentioned in the above background art.

[0005] A preparation method of fractured porous media includes the following steps: Fill glass beads into a container to form a medium sample. During the filling process, select one of thin wood chips, rock salt, and gypsum cement to prepare a fissure-shaped sample according to requirements, and place the fissure-shaped sample inside the medium sample; Put the container with the medium sample into a heating furnace, heat it from room temperature to 700 °C and maintain it at 700 °C for 35 minutes, then cool it to 600 °C and maintain it at 600 °C for 20 minutes, and then stop heating and cool it to room temperature. Take out the medium sample with the residue of the fissure-shaped sample from the container; Remove the residue of the fissure-shaped sample in the medium sample by water flooding to form fractured porous media.

[0006] As a preference of the preparation method of the fractured porous media in the present invention, the particle size distribution of the glass beads in the medium sample conforms to a Gaussian distribution.

[0007] As a preference of the preparation method of the fractured porous media in the present invention, the silica content of the glass beads is not less than 97%.

[0008] As a preference of the preparation method of the fractured porous media in the present invention, the container is a cylindrical graphite crucible with a lid.

[0009] As a preference of the preparation method of the fractured porous media in the present invention, the heating furnace is a muffle furnace with temperature display.

[0010] As a preference of the preparation method of the fractured porous medium in the present invention, the specific steps of selecting one of veneer, rock salt and gypsum cement to prepare the fractured specimen according to requirements are as follows: When the fractures in the fractured porous medium are irregular fractures with small apertures, rock salt is used to prepare the fractured specimen; In other cases, veneer or gypsum cement is used to prepare the fractured specimen. Among them, when the precision requirement is low, veneer is used to prepare the fractured specimen, and when the precision requirement is high, gypsum cement is used to prepare the fractured specimen.

[0011] As a preference of the preparation method of the fractured porous medium in the present invention, when using rock salt to prepare the fractured specimen, the rock salt is wrapped with pure cotton cheese gauze and hand-sewn with cotton thread to form a fractured shape.

[0012] As a preference of the preparation method of the fractured porous medium in the present invention, when using veneer to prepare the fractured specimen, the veneer is stacked to form a fractured shape.

[0013] As a preference of the preparation method of the fractured porous medium in the present invention, when using gypsum cement to prepare the fractured specimen, the gypsum cement is mixed with water to be modulated into a fractured shape.

[0014] As a preference of the preparation method of the fractured porous medium in the present invention, the mixing ratio of the gypsum cement to water is 1:0.3.

[0015] Advantages of the present invention: A preparation method of a fractured porous medium includes the following steps: Fill glass beads into a container to form a medium specimen. During the filling process, select one of veneer, rock salt and gypsum cement to prepare a fractured specimen according to requirements, and place the fractured specimen inside the medium specimen; Put the container with the medium specimen into a heating furnace, heat it from room temperature to 700 °C and maintain it at 700 °C for 35 minutes, then cool it down to 600 °C and maintain it at 600 °C for 20 minutes, and then stop heating and cool it to room temperature. Take out the medium specimen with the residue of the fractured specimen from the container; Remove the residue of the fractured specimen in the medium specimen by water flooding to form a fractured porous medium.

[0016] The preparation method provided by the present invention can control the fracture shape and size to imitate various fracture patterns in real porous media, which is convenient for studying the structural characteristics or stress characteristics under various fracture conditions, and is beneficial to the research on hydraulic conduction and seepage morphology of fractures during rock mechanics experiments. It fills the gap in the preparation of fractured porous media and improves the accuracy and reliability of the research results of rock mechanics experiments. Description of the Drawings

[0017] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic flowchart of the preparation method in the embodiment of the present application; Figure 2 It is a schematic three-dimensional structure diagram of the filling of glass beads and fissured specimens before consolidation in the embodiment of the present application; Figure 3 It is a schematic cross-sectional structure diagram of the filling of glass beads and fissured specimens before consolidation in the embodiment of the present application; Figure 4 It is a step diagram of the heating furnace's temperature rise time in the embodiment of the present application; Figure 5 It is a schematic Gaussian distribution diagram of the particle size of glass bead particles in the embodiment of the present application; Figure 6 It is a schematic plan view of using thin wood slices to make fissured specimens in the embodiment of the present application; Figure 7 It is a schematic plan view of using pure cotton cheese gauze to wrap rock salt to prepare fissured specimens in the embodiment of the present application; Figure 8 It is a schematic plan view of using gypsum cement mixture to prepare fissured specimens in the embodiment of the present application; Explanation of reference numerals: 1. Container; 2. Glass beads; 3. Fissured specimen; 4. Thin wood slice; 5. Rock salt; 6. Gypsum cement; 7. Pure cotton cheese gauze. Detailed implementation manners

[0019] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will make a detailed description of the specific implementation manners of the present application with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein. Those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0020] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0021] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0022] In the present application, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. 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 circumstances.

[0023] In the present application, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0024] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0025] Embodiment This embodiment provides a preparation method for fractured porous media, as Figure 1 shown, including the following steps: Preparation work: Spin a container 1 of a suitable size according to the size of the fractured porous media to be prepared, and prepare a sufficient amount of materials for the preparation of the fissure-shaped specimen 3.

[0026] Fabrication of the medium specimen: Divide the glass beads 2 to be filled into upper and lower parts with the position of the fissure-shaped specimen 3 in the medium specimen as the boundary. First, fill the lower glass beads 2 into the container 1, then select one of the thin wood slices 4, rock salt 5, and gypsum cement 6 to prepare the fissure-shaped specimen 3 according to requirements, and place the fissure-shaped specimen 3 on the top of the lower glass beads 2. Finally, fill the upper glass beads 2 to form a pre-consolidation specimen as Figure 2 and Figure 3 shown.

[0027] Heating preparation: Place the container 1 with the medium specimen into a heating furnace, as Figure 5 shown. First, heat from room temperature to 700 °C and maintain it at 700 °C for 35 minutes, then cool down to 600 °C and maintain it at 600 °C for 20 minutes, and then stop heating and cool to room temperature. Take out the medium specimen with the residue of the fissure-shaped specimen 3 from the container 1. This heating time step can make the glass beads 2 just reach the state of bonding to each other without changing the shape of their spheres, while saving energy and keeping the mechanical properties of the glass beads 2 unchanged after consolidation.

[0028] Water flooding to remove residues: Repeatedly water flood the medium specimen with the residue of the fissure-shaped specimen 3 until the residue of the fissure-shaped specimen 3 is removed.

[0029] In this embodiment, as Figure 5 shown, the particle size distribution of the glass beads 2 in the medium specimen should conform to a Gaussian distribution to make the prepared porous media closer to the actual situation.

[0030] In this embodiment, the silica content of the glass beads 2 is not less than 97%, so as to be closer to the composition of quartz sand in reality.

[0031] In this embodiment, the container 1 is a cylindrical graphite crucible with a lid, which has the characteristics of high temperature resistance and corrosion resistance and is very suitable for loading consolidated samples for high-temperature firing.

[0032] In this embodiment, the heating furnace has a temperature display and the maximum temperature can reach above 700 °C, so as to more accurately control the temperature during the high-temperature firing process.

[0033] When preparing the fissure-shaped specimen 3 using the thin wood chip 4: Stack the 2-mm-thick thin wood chips 4 to form a fissure shape. When removing the residues, the medium specimen with the residues of the fissure-shaped specimen 3 is repeatedly water-driven with deionized water until the combustion residues of the thin wood chips 4 are removed. A pressure difference is set at the inlet and outlet during water driving to facilitate flushing and removing the combustion residues of the thin wood chips 4. The specimen after water driving is placed in a drying furnace for 2 hours, and the drying temperature is 150 °C to remove the liquid, obtaining the specimen as Figure 6 shown.

[0034] When preparing the fissure-shaped specimen 3 using the thin wood chip 4, the fissure-shaped specimen 3 will produce volume changes during the firing process, resulting in a decrease in the accuracy of the fissures. Moreover, the ashes after high-temperature sintering of the thin wood chips 4 are difficult to wash. Therefore, the thin wood chip 4 is suitable for cases where the requirement for the accuracy of the fissures is low.

[0035] When preparing the fissure-shaped specimen 3 using rock salt 5: Wrap the 2-mm rock salt 5 with two layers of pure cotton cheesecloth 7 and hand-sew it with cotton thread to form a fissure shape. When removing the residues, the medium specimen with the residues of the fissure-shaped specimen 3 is immersed in deionized water for 12 hours to dissolve the rock salt 5, and then water-driven to remove the residues of the sintered pure cotton cheesecloth 7, obtaining the specimen as Figure 7 shown.

[0036] When preparing the fissure-shaped specimen 3 using rock salt 5, the fissure-shaped specimen 3 will not produce volume changes during the firing process, and the formed fissures have high accuracy. The ashes generated by the firing of the pure cotton cheesecloth 7 are easy to remove. However, its disadvantage is that when the opening of the fissure is large, the overall shape will change and regular fissures cannot be formed. Therefore, the rock salt 5 is suitable for cases where the fissures in the fissured porous medium are irregular fissures and the opening is small.

[0037] When preparing the fissure-shaped specimen 3 using gypsum cement 6: Mix the gypsum cement 6 with water, modulate and solidify it to form a cylindrical solid with a height of 2 mm, and then make it into a fissure shape. When removing the residues, the medium specimen with the residues of the fissure-shaped specimen 3 is immersed in a hydrochloric acid solution with a concentration of 2 mol / L for 10 hours to dissolve the gypsum. After dissolution, the medium specimen is water-driven and rinsed with deionized water and placed in a drying furnace for 2 hours to remove the liquid, obtaining the specimen as Figure 8 shown.

[0038] When preparing the fissure-shaped specimen 3 using gypsum cement 6, the fissure morphology can be controlled without volume and morphological changes. The drawback is that the water flooding method is rather troublesome and chemical reagents are required. Therefore, gypsum cement 6 is suitable when high precision in fissure formation is required.

[0039] In this embodiment, the mixing ratio of the gypsum cement 6 to water is 1:0.3, which is convenient for fabrication and has a good hardening effect.

[0040] The preparation method of this embodiment can change the fissure morphology (orientation, width, depth, etc.) by changing the shapes of the veneer 4, rock salt 5, and gypsum cement 6, facilitating the study of structural features or stress characteristics under various fissure conditions, and being conducive to the study of aspects such as hydraulic conduction and seepage morphology of fissures during rock mechanics experiments, filling the gap in the preparation of fissured porous media, and improving the accuracy and reliability of the research results of rock mechanics experiments.

[0041] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0042] The above-described embodiments merely represent several implementation manners of this application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. Therefore, the protection scope of the patent of this application shall be subject to the appended claims.

Claims

1. A method for preparing a fractured porous medium, characterized in that: The steps include: Filling glass beads into the container to form a medium sample, during the filling process, selecting one of thin wood chips, rock salt and gypsum cement according to needs to prepare a crack-shaped sample, and placing the crack-shaped sample inside the medium sample; The container with the medium sample is placed in a heating furnace, heated from room temperature to 700°C and maintained at 700°C for 35 minutes, then cooled to 600°C and maintained at 600°C for 20 minutes, then stopped heating and cooled to room temperature, and the medium sample with crack-shaped sample residues is taken out from the container; Water flooding removes the fractured sample residues in the medium sample to form a fractured porous medium.

2. The method for preparing a fractured porous medium according to claim 1, characterized in that: The particle size distribution of the glass beads in the medium sample conforms to the Gaussian distribution.

3. The method for preparing a fractured porous medium according to claim 2, characterized in that: The silicon dioxide content of the glass beads is not less than 97%.

4. The method for preparing a fractured porous medium according to claim 1, characterized in that: The container is a cylindrical graphite crucible with a cover.

5. The method for preparing a fractured porous medium according to claim 1, characterized in that: The heating furnace is a muffle furnace with a temperature display.

6. The method for preparing a fractured porous medium according to claim 1, characterized in that: The method of selecting one of thin wood chips, rock salt and gypsum cement according to the demand to prepare the cracked sample specifically includes: When the cracks in the fractured porous medium are irregular and have a small opening, rock salt is used to prepare the fractured specimens; In other cases, thin wood chips or gypsum cement are used to prepare cracked specimens. When the precision requirement is low, thin wood chips are used to prepare cracked specimens, and when the precision requirement is high, gypsum cement is used to prepare cracked specimens.

7. The method for preparing a fractured porous medium according to claim 6, characterized in that: When the crack-shaped sample is prepared by using rock salt, the rock salt is wrapped with pure cotton cheese gauze and manually sewn with cotton thread to form a crack shape.

8. The method for preparing a fractured porous medium according to claim 6, characterized in that: When using wood veneers to prepare cracked specimens, the wood veneers are stacked to form a crack shape.

9. The method for preparing a fractured porous medium according to claim 6, characterized in that: When gypsum cement is used to prepare cracked specimens, the gypsum cement is mixed with water and adjusted to form a cracked shape.

10. The method for preparing a fractured porous medium according to claim 9, characterized in that: The mixing ratio of the gypsum cement to water is 1:0.3.

Images