Mold for manufacturing fracture rock test pieces with different forms and use method of mold

Abstract

The invention discloses a mold for manufacturing crack type rock test pieces with different forms, the mold comprises an upper section mold, a lower section mold and a replaceable middle section mold, and the middle section mold comprises a mold with different crack forms or a crack-free mold; each of the upper-section mold, the lower-section mold and the middle-section mold is formed by splicing a left semi-arc-shaped mold and a right semi-arc-shaped mold; and movable hinges are fixedly arranged on the side edges of the three semi-arc-shaped molds on the same side and used for being connected with fixing supporting rods in an inserted mode, and nuts are arranged at the upper ends and the lower ends of the fixing supporting rods in a threaded connection mode. And the position of the crack can be changed, diversified test requirements can be met only through a small number of modular assemblies, and the mold machining and storage cost is remarkably reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of geotechnical engineering, and specifically refers to a mold for manufacturing rock specimens with different forms of fractures and its usage method. Background Art

[0002] In engineering practice, rock mass mechanical test samples usually rely on field collection. However, affected by geological processes, the internal fractures of natural rocks exhibit significant non-uniformity and non-continuity characteristics. If standard rock samples with controllable fracture distribution laws are required, it often leads to a substantial increase in test costs. Many studies have shown that rock materials and rock-like materials have high similarity at the level of mechanical parameters. Therefore, researchers generally use rock-like materials as substitutes and prepare fracture simulation specimens with different forms through casting processes.

[0003] Most fractures of traditional molds adopt fixed designs, and their positions and forms are preset and fixed on the molds. This makes it necessary to prepare multiple sets of molds with specific structures when manufacturing rock specimens with different forms of fractures. In addition, existing specimen molds generally adopt an integrated structure, and this non-detachable structural design results in a large resistance when demolding the specimens, and it is extremely easy to cause structural damage to the specimens due to external forces during the operation process.

[0004] Traditional preparation methods mostly directly open fixed fractures on the side walls of the molds. However, the fracture structures of such molds are directly formed on the mold surfaces and are difficult to adapt to the complex and diverse fracture forms in nature (such as single fractures with different dips, cross fractures, etc.). In addition, special fracture molds can only manufacture specimens with defects and cannot simultaneously produce intact comparison specimens without fractures, resulting in difficulty in eliminating systematic errors introduced by mold differences in the test. Moreover, many traditional molds consist of two complete half-molds. When demolding, since one half-mold is an integral whole, problems are likely to affect the whole, thereby damaging the specimens. Finally, due to the fixed fracture forms of traditional molds (such as single fractures), if multiple fracture types need to be covered, it is necessary to separately design and process molds for each form, thereby resulting in a relatively high research cost investment. In view of the above technical bottlenecks, the present invention proposes a three-section combined mold suitable for manufacturing rock specimens with multi-form fractures, and realizes flexible regulation of fracture forms and rapid switching of specimen types through modular design. Summary of the Invention

[0005] To solve the above technical problems, the technical solution of the present invention is: a mold for manufacturing rock specimens with different forms of fractures, the mold includes an upper-section mold, a lower-section mold, and a replaceable middle-section mold. The upper-section mold, the lower-section mold, and the middle-section mold are all designed to be detachable. The middle-section mold includes molds with different fracture forms or molds without fractures.

[0006] The mold further includes fixed support rods that penetrate the mold body and provide structural support in the vertical direction; the upper-section mold, the lower-section mold, and the middle-section mold are each composed of two semi-circular arc molds spliced together. At the upper and lower ends on the outer sides of the upper-section mold, the lower-section mold, and the middle-section mold, discs for upper and lower connection and fixation are fixedly provided; on the sides of the three semi-circular arc molds on the same side, movable hinges are fixedly provided for inserting the fixed support rods, and nuts are threadedly connected to both the upper and lower ends of the fixed support rods.

[0007] Further, the middle-section mold includes at least one of the following types: a middle-section mold without cracks; a middle-section mold with a 45° inclined crack; and a middle-section mold with a cross crack. Inside the cracks, crack steel plates corresponding to the shapes of the cracks are movably inserted for forming the crack structure of the rock-like specimen.

[0008] Further, the crack steel plates penetrate the middle-section mold and steel plate handles are fixedly provided at the ends for periodically pulling during the specimen curing process to prevent the steel plates from adhering to the specimen material.

[0009] Further, fixing holes are provided on the discs, and adjacent discs are fixedly connected by bolts II.

[0010] Further, the two semi-circular arc molds on the left and right in the upper-section mold, the lower-section mold, and the middle-section mold are detachably fixed by bolts.

[0011] Further, the position of the crack on the sample is changed by changing the position of the middle-section mold relative to the upper-section mold, and a mold bottom plate is fixedly provided at the bottom of the lower-section mold.

[0012] On the other hand, the present invention provides a method for using a mold for manufacturing rock-like specimens with different forms of cracks, including the following steps:

[0013] Step 1: Select the corresponding middle-section mold according to the target crack form, and insert the semi-circular arc molds with movable hinges in the upper-section mold, the lower-section mold, and the middle-section mold together through the fixed support rods and fix them through the discs and bolts II. The other three groups of semi-circular arc molds are sequentially fixed through the discs and bolts II to form the left overall mold and the right overall mold;

[0014] Step 2: Uniformly coat the inner walls of the left overall mold and the right overall mold and the surfaces of the crack steel plates with a release agent, then assemble the left overall mold and the right overall mold into a whole through bolts, and insert the corresponding crack steel plates into the cracks of the middle-section mold;

[0015] Step 3: Pour the rock-like material mixture into the mold, vibrate to remove air bubbles and level the surface;

[0016] Step 4: Periodically twitch the fissure steel plate during the curing process, and remove the steel plate after the curing is completed;

[0017] Step 5: Remove the bolts and nuts of the mold, disassemble the mold into six parts, and take out the complete specimen. By assembling different forms of fissure molds or non-fissure molds, different forms of fissured rock specimens can be made.

[0018] The advantages of the present invention compared with the prior art are as follows:

[0019] 1. Flexibility and economy: By replacing the middle section mold, different fissure forms (such as inclined and cross fissures) can be quickly switched. By changing the up and down positions of the middle section mold, the position of the fissure can be changed. Only a small number of modular components are required to meet diverse test requirements, significantly reducing the mold processing and storage costs.

[0020] 2. High precision and stability: The dual alignment design of the disc and the fixed support rod ensures the accuracy during mold assembly and reduces the forming error of the specimen.

[0021] 3. Convenient demolding and specimen protection: The mold can be disassembled into 6 independent parts, with small demolding resistance, avoiding damage to the specimen caused by traditional integral molds and improving the integrity rate of the specimen.

[0022] 4. Versatility: By replacing the non-fissure middle section mold, complete specimens can be prepared synchronously, eliminating the mold difference error in the comparative test and improving the reliability of test data. Description of the Drawings

[0023] Figure 1 is the overall structural schematic diagram of the present invention.

[0024] Figure 2 is the internal structural schematic diagram of the present invention.

[0025] Figure 3 is the structural schematic diagram of the cross fissure mold in the present invention.

[0026] Figure 4 is the structural schematic diagram of the non-fissure mold in the present invention.

[0027] As shown in the figure: 1. Fixed support rod; 2. Movable hinge; 3. Upper section mold; 4. Bolt; 5. Middle section mold; 6. Lower section mold; 7. Nut; 8. Bolt II; 9. Disc; 10. Fissure steel plate; 11. Steel plate handle; 12. Fixed hole; 13. Right part mold with movable hinge; 14. 45° inclined fissure steel plate; 15. Mold bottom plate; 16. Left part mold; 17. Cross fissure middle section mold; 18. Non-fissure middle section mold. Detailed Embodiments

[0028] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "center", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation structure and operation. Therefore, it should not be construed as a limitation to the present invention.

[0029] In the description of the present invention, it should also be noted that unless otherwise clearly specified and defined, terms such as "provided with", "installed", "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; 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 invention can be understood according to specific circumstances.

[0030] The present invention will be further described in detail below with reference to the accompanying drawings.

[0031] Combined with the attached Figure 1 to the attached Figure 4 , a mold for manufacturing rock specimens with different forms of fractures, the mold includes an upper mold 3, a lower mold 6, and a replaceable middle mold 5. The upper mold 3, the lower mold 6, and the middle mold 5 are all of detachable design. The middle mold 5 includes molds with different fracture forms or a mold without fractures.

[0032] The mold further includes a fixed support rod 1 for penetrating the mold body and providing structural support in the vertical direction. The upper mold 3, the lower mold 6, and the middle mold 5 are all composed of two semi-circular arc molds spliced together. At the upper and lower ends of the outer sides of the upper mold 3, the lower mold 6, and the middle mold 5, discs 9 for upper and lower connection and fixation are fixedly provided. Fixing holes 12 are provided on the discs 9, and adjacent discs 9 are fixedly connected by bolts 8. On the sides of the three semi-circular arc molds on the same side, movable hinges 2 are fixedly provided for inserting and fixing the support rod 1. Nuts 7 are threadedly connected to both the upper and lower ends of the support rod 1.

[0033] The middle mold 5 includes at least one of the following types: a middle mold 18 without fractures; a middle mold with 45° inclined fractures and a middle mold with cross fractures. A fracture steel plate 10 corresponding to the fracture shape is movably inserted into the fracture for forming the fracture structure of the rock-like specimen.

[0034] The fracture steel plate 10 penetrates the middle mold 5 and a steel plate handle 11 is fixedly provided at the end for periodically pulling during the specimen curing process to prevent the steel plate from adhering to the specimen material.

[0035] The two semi-circular molds on the left and right in the upper mold 3, the lower mold 6 and the middle mold 5 are detachably fixed by bolts 4. The middle mold 5 changes its position relative to the upper mold 3 to change the position of the crack on the sample. A mold bottom plate 15 is fixedly provided at the bottom of the lower mold 6.

[0036] On the other hand, the present invention provides a method for using a mold for fabricating rock specimens with cracks of different forms, comprising the following steps:

[0037] Step 1: Select the corresponding middle mold 5 according to the target crack form, and insert the semi-circular molds with movable hinges 2 in the upper mold 3, the lower mold 6 and the middle mold 5 together through the fixed support rods 1, and fix them through the discs 9 and bolts II 8. The other three groups of semi-circular molds are sequentially fixed through the discs 9 and bolts II 8 to form the left integral mold and the right integral mold;

[0038] Step 2: Uniformly coat the inner walls of the left integral mold and the right integral mold and the surface of the crack steel plate with a release agent, then assemble the left integral mold and the right integral mold into a whole through bolts 4, and insert the corresponding crack steel plate into the crack of the middle mold 5;

[0039] Step 3: Pour the rock-like material mixture into the mold, vibrate to remove air bubbles and level the surface;

[0040] Step 4: Periodically pull out the crack steel plate during the curing process, and remove the steel plate after curing;

[0041] Step 5: Disassemble the bolts 4 and nuts 7 of the mold, disassemble the mold into six parts and then take out the complete specimen. By assembling different forms of crack molds or crack-free molds, rock specimens with cracks of different forms can be fabricated.

[0042] The working process of the present invention is as follows: Taking the fabrication of a rock specimen with a 45° inclined crack as an example: First, insert the lower mold of the right part, i.e., the part with the movable hinge, the middle mold with a 45° inclined crack, and the upper mold into the fixed support rod 1 in sequence. The upper and lower ends of the fixed support rod 1 are fixed by nuts 7. Then align the fixing holes 12 on the middle disc 9 of the three parts of the mold and fix them with bolts II 8. The three parts of the mold on the corresponding left part are also fixed with bolts II 8 on the disc 9. At this time, the six parts of the mold have become the left integral mold and the right integral mold. Then use a brush to evenly brush the release agent on the inner part of the mold and the crack steel plate, and then assemble the left and right parts of the mold together through the bolts 4 on the side. Insert the 45° crack steel plate into the crack of the middle mold 5. After assembly, place it on the experimental table for standby.

[0043] After sieving the similar material of the rock, weigh the dry river sand and Portland cement according to the mix ratio and perform dry mixing first. After dry mixing evenly, add the weighed water (add part of the defoamer to the water and stir evenly first) into the mixer and continue wet mixing. After wet mixing is completed, slowly pour the evenly wet-mixed mortar into the mold (the mold needs to be placed on the vibrating table), vibrate to make the surface have no obvious bubbles, then level the surface, and then cover the surface with a plastic film. If the weather is dry, sprinkle water on the film to keep it moist to promote cement hydration. During the curing process, in order to avoid the steel plate from solidifying in the mortar, every hour, slowly push and pull the steel plate back and forth several times along the length direction of the steel plate through the steel plate handle. After curing for 8-10 hours, pull out the fissure steel plate. After curing for 24 hours, disassemble the mold into 6 parts by removing bolt 4 and bolt two 8 for demolding, and then clean the mold. After that, by assembling different-shaped fissure molds or non-fissure molds, different-shaped fissure-like rock specimens can be made.

[0044] The above describes the present invention and its implementation manners. This description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar structural modes and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A mold for making fractured rock specimens of different forms, characterized in that: The mold comprises an upper mold (3), a lower mold (6) and a replaceable middle mold (5); the upper mold (3), the lower mold (6) and the middle mold (5) are all detachable; the middle mold (5) comprises a mold with different crack shapes or a mold without cracks; Also included is a fixed support rod (1) for penetrating the mold body and providing structural support in a vertical direction; The upper mold (3), the lower mold (6) and the middle mold (5) are all formed by splicing two semicircular arc molds on the left and right. The upper and lower ends of the outer sides of the upper mold (3), the lower mold (6) and the middle mold (5) are fixed with disks (9) for connecting and fixing the upper and lower ends. The three semicircular arc-shaped mold sides on the same side are all fixedly provided with movable hinges (2) for inserting and fixing the support rod (1), and the upper and lower ends of the fixed support rod (1) are both threadedly connected with nuts (7).

2. The mold for fabricating fractured rock specimens with different morphologies according to claim 1, characterized in that: The middle section mold (5) comprises at least one of the following types: a middle section mold (18) without cracks; a middle section mold with a crack inclined at 45° and a middle section mold with a cross crack, wherein a crack steel plate (10) corresponding to the shape of the crack is movably inserted inside the crack to form a crack structure of a rock-like specimen.

3. The mold for fabricating fractured rock specimens with different morphologies according to claim 2, wherein: The cracked steel plate (10) passes through the middle section mold (5) and a steel plate handle (11) is fixedly provided at the end thereof, which is used for periodically pulling during the specimen curing process to prevent the steel plate from bonding with the specimen material.

4. The mold for fabricating fractured rock specimens with different forms according to claim 1, characterized in that: The disc (9) is provided with a fixing hole (12), and adjacent discs (9) are fixedly connected by bolts (8).

5. The mold for fabricating fractured rock specimens with different morphologies according to claim 1, wherein: The upper mold (3), the lower mold (6) and the left and right semicircular arc molds in the middle mold (5) are detachably fixed by bolts (4).

6. The mold for fabricating fractured rock specimens with different morphologies according to claim 1, wherein: The middle section mold (5) changes the position of the crack on the sample by changing its position with the upper section mold (3), and a mold bottom plate (15) is fixedly provided at the bottom of the lower section mold (6).

7. A method for using a mold for fabricating rock specimens with different forms of fractures as described in any one of claims 1-6, characterized in that, The following steps are involved: Step 1: Select the corresponding middle section mold (5) according to the target crack shape, and plug the upper section mold (3), the lower section mold (6) and the semicircular arc mold with the movable hinge (2) in the middle section mold (5) together through the fixed support rod (1), and fix them through the disc (9) and the second bolt (8), and the other three groups of semicircular arc molds are fixed in turn through the disc (9) and the second bolt (8) to form the left overall mold and the right overall mold; Step 2: evenly apply a release agent on the inner wall of the left integral mold and the right integral mold and the surface of the cracked steel plate, then assemble the left integral mold and the right integral mold into a whole by bolts (4), and insert the corresponding cracked steel plate into the crack of the middle section mold (5); Step 3: Pour the rock-like material mixture into the mold, vibrate to remove air bubbles and smooth the surface; Step 4: Periodically pull the cracked steel plate during the curing process and remove the steel plate after the curing is completed; Step 5: Remove the bolts (4) and nuts (7) of the mold, split the mold into six parts and take out the complete test piece. By assembling different forms of fracture molds or non-fracture molds, different forms of fractured rock test pieces can be made.

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