Fixing mold for double-particle cemented sand sample and use method of fixing mold

Abstract

The invention discloses a double-particle cemented sand sample fixing mold which comprises a limiting table, a fixing plate, sample cushion blocks and a pressing block, an L-shaped groove is formed in the surface of the limiting table and used for guiding and positioning the two sample cushion blocks, and cylindrical grooves are formed in the surfaces of the sample cushion blocks and used for being filled with epoxy resin glue. Two ends of a double-particle cemented sand sample are respectively bonded and fixed in the cylindrical grooves of the two sample cushion blocks; the pressing block can move up and down along the L-shaped groove and acts on the upper surface of the sample cushion block located above to play a pre-pressing role; the limiting table and the fixing plate are connected through four bolts, and the two sample cushion blocks are clamped. The invention further provides a using method of the fixing mold for the double-particle cemented sand sample. The mold is low in manufacturing cost, multiple sets of double-particle cemented sand samples can be bonded and fixed outside the loading device at the same time, meanwhile, the upper sample cushion block and the lower sample cushion block are fixed in the loading device, and a series of micromechanics tests of complex loading paths can be conducted on the double-particle cemented sand samples.

Description

Technical Field

[0001] The invention relates to the field of geotechnical engineering tests, in particular to a fixed mold for a double-particle cemented sand sample and a use method thereof. Background Art

[0002] The mechanical properties of cemented sand are closely related to actual engineering. For example, most islands, reefs, and sandbanks are based on coral reefs, which are formed by the accumulation of corals and other marine biological debris such as shell fragments, forming a large amount of weakly cemented calcareous sand covering their surface. These weakly cemented calcareous sands and shallowly accumulated calcareous sands on islands and reefs are often used as foundation backfill materials in island construction projects.

[0003] However, most of the current research on the mechanical behavior of cemented sand remains at the macroscopic level. At the microscopic level, due to the small scale, it is difficult to conduct relevant experiments. There is a lack of understanding of the contact mechanical properties between its internal particles and the cementing layer. The connection between the crushing behavior of cemented sand and the macroscopic mechanical response is still unclear, which essentially limits our comprehensive understanding of structural soils such as cemented sand. Therefore, it is necessary to study the mechanical behavior of cemented sand at the microscopic scale and conduct a series of combined load tests on cemented sand at the particle scale in order to fundamentally grasp the physical and mechanical properties of cemented sand, especially the microscopic real particles.

[0004] In the existing cemented sand microscopic loading device, such as patent CN 113155617A, for the prefabricated double-grained cemented sand samples, epoxy resin glue is used to bond and fix them in the device during the test preparation stage. Although the solution is feasible, since the epoxy resin glue needs more than 24 hours to fully cure at room temperature, the time used in the test preparation stage is much longer than the test loading stage, which limits the efficiency of loading the double-grained cemented sand samples. In order to improve the loading efficiency, the double-grained cemented sand samples can be bonded and fixed in batches outside the device and then loaded. Summary of the invention

[0005] The purpose of the present invention is to address the above-mentioned problems and provide a fixed mold for a double-particle cemented sand sample and a method for using the same, so that the test preparation work before loading the double-particle cemented sand sample can be carried out in batches outside the loading device, thereby improving the loading efficiency of the double-particle cemented sand sample.

[0006] The purpose of the present invention can be achieved by adopting the following technical solutions:

[0007] A fixed mold for a double-particle cemented sand sample, comprising a limit platform, a fixed plate, a sample pad and a pressure block, wherein the limit platform surface is provided with an L-shaped groove for guiding and positioning the sample pad, two sample pads are placed in the L-shaped groove, the surface of the sample pad is provided with a cylindrical groove for filling epoxy resin glue, and the two ends of the double-particle cemented sand sample are respectively bonded and fixed in the cylindrical grooves of the two sample pads; the pressure block is composed of a guide section and a counterweight section, the guide section of the pressure block is in contact with the inner wall of the L-shaped groove, the pressure block can move up and down in the L-shaped groove, and the pressure block acts on the upper surface of the sample pad located above to play a pre-compression role; the limit platform is connected to the fixed plate by bolts.

[0008] As a preferred solution, the bottom surface of the L-shaped groove is a horizontal surface, and the lower surface of the sample pad located below is in direct contact with the bottom surface of the L-shaped groove.

[0009] As a preferred solution, the fixed plate is provided with four through holes, the limit platform is provided with four threaded holes corresponding to the positions of the through holes, the through holes and the threaded holes are both provided with bolts, the vertical projection width of the sample pad is slightly larger than the width of the L-shaped groove, the limit platform is not in direct contact with the fixed plate, and the limit platform and the fixed plate are connected by bolts to clamp the two sample pads.

[0010] As a preferred solution, the pressing block is an axisymmetric structure, acting on the center of the sample pad, so that the sample pad and the double-grained cemented sand sample fit tightly, which is conducive to the full bonding of the epoxy resin glue with the sample pad and the double-grained cemented sand sample.

[0011] As a preferred solution, the guide section of the pressing block is reserved with sufficient length to meet the bonding requirements of double-grained cemented sand samples of different heights.

[0012] A method for using a fixed mold for a double-grain cemented sand sample, characterized in that it comprises the following steps:

[0013] S1. Apply WD-40 lubricant to the inner wall of the L-shaped groove of the limit table;

[0014] S2. Apply epoxy resin glue to the cylindrical groove of the sample pad located below, and at the same time, fix the bottom of the double-grain cemented sand sample in the cylindrical groove, and wait for the epoxy resin glue to initially harden. During this period, keep the double-grain cemented sand sample in a vertical position;

[0015] S3. First, apply epoxy resin glue to the cylindrical groove of the sample pad located at the top, then bond and fix the top of the double-grain cemented sand sample in the cylindrical groove, and finally put the two sample pads bonded with the upper and lower ends of the double-grain cemented sand sample into the limit table along the L-shaped groove. This step should be completed before the epoxy resin glue hardens;

[0016] S4, align the threaded hole of the limit table with the through hole of the fixed plate, put the pressing block into the limit table along the L-shaped groove, gently press the limit table, the fixed plate and the pressing block by hand to ensure that the two sample pads are close to the L-shaped groove, and the upper surfaces (lower surfaces) of the two sample pads are parallel to each other, and then slowly tighten the four bolts alternately in sequence to complete the bonding and fixing of the double-grain cemented sand sample. This step should be completed before the epoxy resin glue in step S3 hardens;

[0017] S5. After the epoxy resin glue is completely hardened, loosen the four bolts alternately and slowly, remove the fixing plate, first take out the pressing block along the L-shaped groove, and then slowly take out the double-grain cemented sand sample fixed to the two sample pads along the L-shaped groove;

[0018] S6. Fix the upper and lower sample pads in the loading device and conduct micromechanical tests on the double-grained cemented sand samples in compression, compression-shear, compression-bending-shear and other loading paths to study the micromechanical properties of the cemented sand.

[0019] The implementation of the present invention has the following beneficial effects:

[0020] 1. The mold of the present invention can realize the bonding and fixing of double-particle cemented sand samples outside the loading device. The mold manufacturing cost is low, and the preparation work can be carried out in large quantities in advance. The time consumed by the hardening of epoxy resin glue has a greatly reduced impact on the progress of the test. Batch sample preparation and batch loading can be realized, thereby improving the loading efficiency of double-particle cemented sand samples.

[0021] 2. The limit platform and the fixed plate proposed in the present invention are connected by bolts to clamp the sample pad, and the pressure block pre-presses the sample pad to ensure that the two sample pads are tightly attached to the L-shaped groove, and the upper surfaces (lower surfaces) of the two sample pads are parallel to each other, thereby avoiding the influence of eccentricity on the double-grained cemented sand sample during loading. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a structural schematic diagram of a fixed mold for a double-particle cemented sand sample of the present invention.

[0024] Figure 2 It is a schematic structural diagram of the fixed mold of the double-particle cemented sand sample of the present invention after the fixed plate is removed.

[0025] Figure 3This is a schematic diagram of the structure of the limiter of the fixed mold of the double-grain cemented sand sample of the present invention.

[0026] Figure 4 It is a structural schematic diagram of a fixed plate of a fixed mold for a double-particle cemented sand sample of the present invention.

[0027] Figure 5 It is a structural schematic diagram of a sample pad of a fixed mold for a double-particle cemented sand sample of the present invention.

[0028] Figure 6 It is a schematic structural diagram of a pressing block of a fixed mold for a double-grain cemented sand sample of the present invention.

[0029] Figure 7 It is a left view of the fixed mold of the double-particle cemented sand sample of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example

[0032] Reference Figures 1 to 7 The present embodiment relates to a fixed mold for a double-particle cemented sand sample, comprising a limit platform 1, a fixed plate 2, a sample pad 3 and a pressure block 4. The limit platform 1 is provided with an L-shaped groove 11 on its surface for guiding and positioning the sample pad 3. Two sample pads 3 are placed in the L-shaped groove 11. The surface of the sample pad 3 is provided with a cylindrical groove 31 for filling epoxy resin glue. The two ends of the double-particle cemented sand sample 5 are respectively bonded and fixed in the cylindrical grooves 31 of the two sample pads 3; the pressure block 4 is composed of a guide section 41 and a counterweight section 42. The guide section 41 of the pressure block 4 is in contact with the inner wall of the L-shaped groove 11. The pressure block 4 can move up and down in the L-shaped groove 11. The pressure block 4 acts on the upper surface of the sample pad 3 located above to play a pre-pressing role; the limit platform 1 and the fixed plate 2 are connected by bolts 6.

[0033] The bottom surface of the L-shaped groove 11 is a horizontal surface, and the lower surface of the sample pad 3 located below is in direct contact with the bottom surface of the L-shaped groove 11 .

[0034] The fixing plate 2 is provided with four through holes 21, and the limiting platform 1 is provided with four threaded holes 12 corresponding to the positions of the through holes 21. Bolts 6 are provided on the through holes 21 and the threaded holes 12. The vertical projection width of the sample pad 3 is slightly larger than the width of the L-shaped groove 11. The limiting platform 1 is not in direct contact with the fixing plate 2. The limiting platform 1 and the fixing plate 2 are connected by bolts 6 to clamp the two sample pads 3.

[0035] The pressing block 4 is an axisymmetric structure, acting on the center of the sample pad 3, so that the sample pad 3 and the double-grain cemented sand sample 5 fit tightly, which is conducive to the full bonding of the epoxy resin glue with the sample pad 3 and the double-grain cemented sand sample 5.

[0036] The guide section 41 of the pressing block 4 has a sufficient length to meet the bonding requirements of double-grained cemented sand samples 5 of different heights.

[0037] The mold of the present invention can realize the bonding and fixing of the double-grain cemented sand sample outside the loading device, the mold manufacturing cost is low, and the preparation work can be carried out in advance in large quantities at the same time, thereby improving the loading efficiency of the double-grain cemented sand sample. At the same time, the limit table and the fixed plate proposed by the present invention are connected by bolts to clamp the sample pads and the pressure block pre-presses the sample pads to ensure that the two sample pads are close to the L-shaped groove, and the upper surfaces (lower surfaces) of the two sample pads are parallel to each other, avoiding the double-grain cemented sand sample from being affected by the eccentric effect during loading.

[0038] This embodiment also provides a method for using a fixed mold for a double-particle cemented sand sample, which is characterized by comprising the following steps:

[0039] S1. Apply lubricant to the inner wall of the L-shaped groove 11 of the limiting platform 1; the lubricant is WD-40 lubricant.

[0040] S2, applying epoxy resin glue to the cylindrical groove 31 of the sample pad 3 located below, and at the same time, bonding and fixing the bottom of the double-grain cemented sand sample 5 in the cylindrical groove 31, waiting for the epoxy resin glue to initially harden, during which time the double-grain cemented sand sample 5 is kept in a vertical posture;

[0041] S3, first apply epoxy resin glue to the cylindrical groove 31 of the sample pad 3 located at the top, then bond and fix the top of the double-grain cemented sand sample 5 in the cylindrical groove 31, and finally put the two sample pads 3 bonded with the upper and lower ends of the double-grain cemented sand sample 5 into the limit table 1 along the L-shaped groove 11. This step should be completed before the epoxy resin glue hardens;

[0042] S4, align the threaded hole 12 of the limit platform 1 and the through hole 21 of the fixing plate 2, put the pressing block 4 into the limit platform 1 along the L-shaped groove 11, gently press the limit platform 1, the fixing plate 2 and the pressing block 4 by hand, ensure that the two sample pads 3 are close to the L-shaped groove 11, and the upper surfaces (lower surfaces) of the two sample pads 3 are parallel to each other, and then slowly tighten the four bolts 6 alternately in sequence to complete the bonding and fixing of the double-grain cemented sand sample 5. This step should be completed before the epoxy resin glue in step S3 hardens;

[0043] S5. After the epoxy resin glue is completely hardened, loosen the four bolts alternately and slowly in turn, remove the fixing plate 2, first take out the pressing block 4 along the L-shaped groove 11, and then slowly take out the double-grain cemented sand sample 5 bonded and fixed to the two sample pads 3 along the L-shaped groove 11 as a whole;

[0044] S6. Fix the upper and lower sample pads 3 in the loading device, and conduct micromechanical tests on the double-grained cemented sand sample 5 in loading paths such as compression, compression shear, and compression bending shear to study the micromechanical properties of the cemented sand.

[0045] The above disclosure is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A fixed mold for a double-grain cemented sand sample, characterized in that: It includes a limit platform, a fixed plate, a sample pad and a pressure block. The surface of the limit platform is provided with an L-shaped groove for guiding and positioning the sample pad. Two sample pads are placed in the L-shaped groove. The surface of the sample pad is provided with a cylindrical groove for filling with epoxy resin glue. The two ends of the double-particle cemented sand sample are respectively bonded and fixed in the cylindrical grooves of the two sample pads; the pressure block is composed of a guide section and a counterweight section. The guide section of the pressure block is in contact with the inner wall of the L-shaped groove. The pressure block can move up and down in the L-shaped groove. The pressure block acts on the upper surface of the sample pad located above to play a pre-pressing role; the fixed plate is provided with four through holes, and the limit platform is provided with four threaded holes corresponding to the positions of the through holes. The limit platform is connected to the fixed plate by bolts.

2. A fixed mold for a double-grain cemented sand sample according to claim 1, characterized in that: The bottom surface of the L-shaped groove is a horizontal surface, and the lower surface of the sample pad located below is in direct contact with the bottom surface of the L-shaped groove.

3. A fixed mold for a double-grain cemented sand sample according to claim 1, characterized in that: The fixing plate is provided with four through holes, and the limit platform is provided with four threaded holes corresponding to the positions of the through holes. Bolts are provided on the through holes and the threaded holes. The vertical projection width of the sample pad is slightly larger than the width of the L-shaped groove. The limit platform is not in direct contact with the fixing plate, and the limit platform and the fixing plate are connected by bolts to clamp the two sample pads.

4. A fixed mold for a double-grain cemented sand sample according to claim 1, characterized in that: The pressing block is an axisymmetric structure and acts on the center of the sample cushion block, so that the sample cushion block and the double-grain cemented sand sample are closely fitted.

5. A fixed mold for a double-grain cemented sand sample according to claim 1, characterized in that: The guide section of the pressing block is reserved with sufficient length to meet the bonding requirements of double-grain cemented sand samples of different heights.

6. A method for using a fixed mold for a double-grained cemented sand sample according to claims 1 to 5, characterized in that: The following steps are involved: S1. Apply WD-40 lubricant to the inner wall of the L-shaped groove of the limit table; S2. Apply epoxy resin glue to the cylindrical groove of the sample pad located below, and at the same time, fix the bottom of the double-grain cemented sand sample in the cylindrical groove, and wait for the epoxy resin glue to initially harden. During this period, keep the double-grain cemented sand sample in a vertical position; S3. First, apply epoxy resin glue to the cylindrical groove of the sample pad located at the top, then bond and fix the top of the double-grain cemented sand sample in the cylindrical groove, and finally put the two sample pads bonded with the upper and lower ends of the double-grain cemented sand sample into the limit table along the L-shaped groove. This step should be completed before the epoxy resin glue hardens; S4, align the threaded hole of the limit table with the through hole of the fixed plate, put the pressing block into the limit table along the L-shaped groove, gently press the limit table, the fixed plate and the pressing block by hand to ensure that the two sample pads are close to the L-shaped groove, and the upper surfaces (lower surfaces) of the two sample pads are parallel to each other, and then slowly tighten the four bolts alternately in sequence to complete the bonding and fixing of the double-grain cemented sand sample. This step should be completed before the epoxy resin glue in step S3 hardens; S5. After the epoxy resin glue is completely hardened, loosen the four bolts alternately and slowly, remove the fixing plate, first take out the pressing block along the L-shaped groove, and then slowly take out the double-grain cemented sand sample fixed to the two sample pads along the L-shaped groove; S6. Fix the upper and lower sample pads in the loading device and conduct micromechanical tests on the double-grained cemented sand samples in compression, compression-shear, compression-bending-shear and other loading paths to study the micromechanical properties of the cemented sand.

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