Sample preparation device suitable for CT scanning fractured soil triaxial test

Abstract

The utility model provides a sample preparation device suitable for a CT scanning fractured soil triaxial test, and relates to the technical field of fractured soil research, the sample preparation device comprises a lower beveled pile casing, an upper beveled pile casing and a fixing assembly, the top of the lower beveled pile casing is provided with an inclined beveled plane, the bottom of the upper beveled pile casing is provided with an inclined beveled plane, and the fixing assembly is provided with a fixing assembly. The lower beveled pile casing and the upper beveled pile casing can form a cylindrical pile casing after being in butt joint, and the fixing assembly can fix the lower beveled pile casing and the upper beveled pile casing. The lower beveled protective cylinder and the upper beveled protective cylinder are both made of plastics. The cylindrical pile casing is composed of the lower beveled pile casing and the upper beveled pile casing, so that sample disassembly and sample loading are facilitated, when a crack is manufactured, the upper beveled pile casing is taken down, a soil engineering knife is used for manufacturing a soil sample beveled plane and the crack, and manufacturing of a crack soil sample is achieved. The lower beveled protective cylinder and the upper beveled protective cylinder are both made of plastic and can be suitable for CT scanning.

Description

Technical Field

[0001] The utility model relates to the technical field of fissured soil research, in particular to a sample preparation device suitable for CT scanning fissured soil triaxial test. Background Art

[0002] Fractured soil is a kind of soil with primary cracks produced by geological action in nature. The cracks can be waxy crack surfaces or weak interlayers filled with gray-white clay. Cracks in natural rock and soil have different distribution ranges, spacing, inclination, arrangement direction and shape. A large number of literatures show that crack strength plays a controlling role in engineering hazards such as foundation deformation and slope instability. How to obtain the strength of fractured soil and its variation law through indoor tests to provide a basis for the design, construction and construction of geotechnical engineering and water conservancy projects is an important issue currently faced. In the indoor triaxial strength test of fractured soil, on the one hand, conventional triaxial sample preparation equipment cannot meet the preparation of fractured soil samples; on the other hand, in order to accurately obtain the fracture surface morphology of fractured soil for sample preparation, CT technology is also needed to observe the microstructure of fractured soil. However, the existing triaxial sample preparation devices are made of metal materials such as stainless steel and aluminum, which cannot be penetrated by X-rays and are not suitable for use on CT scanners. In addition, it is very troublesome to disassemble and install the entire device, and the fractured soil samples are often damaged during the test. Therefore, it is of great significance to provide a triaxial test sample preparation device for fractured soil suitable for CT scanning. Utility Model Content

[0003] The utility model aims to provide a sample preparation device suitable for CT scanning triaxial test of fissured soil, so as to solve the problems existing in the above-mentioned prior art, facilitate the preparation of fissured soil samples, and be suitable for CT scanning.

[0004] To achieve the above purpose, the utility model provides the following solutions:

[0005] The utility model provides a sample preparation device suitable for CT scanning fissured soil triaxial test, comprising: a lower beveled casing, an upper beveled casing and a fixing assembly, wherein the top of the lower beveled casing is provided with an inclined beveled surface, the bottom of the upper beveled casing is provided with an inclined beveled surface, the lower beveled casing and the upper beveled casing can form a cylindrical casing after being butted against each other, and the fixing assembly can fix the lower beveled casing and the upper beveled casing; the lower beveled casing and the upper beveled casing are both made of plastic.

[0006] Preferably, the fixing assembly includes an upper guard ring base, a lower guard ring base and a plurality of guard posts, the lower beveled guard tube and the upper beveled guard tube are arranged between the upper guard ring base and the lower guard ring base, the circumferential edges of the upper guard ring base and the lower guard ring base are fixedly provided with a pair of ear plates, a mounting groove is formed between each pair of ear plates, the mounting grooves on the upper guard ring base and the lower guard ring base correspond to each other one by one, the bottom of the guard post is hingedly connected to the mounting groove at the bottom, the portion of the guard post close to the top is provided with a thread, and rotating the guard post can make the top of the guard post enter the mounting groove at the top, and the top of the guard post can be threadedly connected to a nut.

[0007] Preferably, sliding holes arranged opposite to each other are arranged on the beveled surfaces of the lower beveled protective tube and the upper beveled protective tube, and the sliding holes are used to insert cylindrical rods. A plurality of threaded holes are arranged at a certain interval on the outside of each of the sliding holes, and the threaded holes are used to pass clamping bolts, and the clamping bolts can extend into the sliding holes and clamp and fix the cylindrical rod.

[0008] Preferably, the cylindrical rod has scales along its length direction.

[0009] Preferably, it also includes a sampling base, which is arranged between the lower guard ring base and the lower beveled casing, and the sampling base is provided with a pore pressure test channel and a water and air guiding channel which pass through the upper and lower surfaces, and a clamping hole which is recessed inward to a certain depth and matches the bottom rod of the triaxial instrument is provided at the center of the lower surface.

[0010] Preferably, the striking base includes a cylinder and a three-opening L-shaped arc sleeve. A circle of grooves is provided on the outer edge of the upper surface of the cylinder. Three bolt holes are evenly distributed along the circumferential direction on the outer side of the upper part of the cylinder, corresponding to the three L-shaped arc sleeves respectively. During the test, the top of the cylinder is used to bind the rubber film.

[0011] Preferably, it also includes a water-permeable plastic plate and filter paper. During production, the bottom and top of the soil in the cylindrical casing are both paved with the water-permeable plastic plate and the filter paper.

[0012] Preferably, it also includes a pad, which is used to pad the bottom of the soil in the lower bevel casing.

[0013] Compared with the prior art, the utility model has achieved the following technical effects:

[0014] The cylindrical casing in the utility model is composed of two separate parts, namely, a lower beveled casing and an upper beveled casing, which is convenient for sample removal and sample loading. When making cracks, only the upper beveled casing is removed and a geotechnical knife is used to make the soil sample bevel surface and cracks, thereby realizing the production of cracked soil samples. In addition, the lower beveled casing and the upper beveled casing are both made of transparent plastic and can be suitable for CT scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of the structure of a sample preparation device suitable for CT scanning triaxial test of fissured soil provided in an embodiment of the utility model;

[0017] Figure 2 for Figure 1 A front view of

[0018] Figure 3 for Figure 1 Side view of

[0019] Figure 4 for Figure 1 A top view of

[0020] Figure 5 is a schematic diagram of the structure of the gasket;

[0021] Figure 6 It is a schematic diagram of the structure of the upper beveled casing and the lower beveled casing;

[0022] Figure 7 It is a structural schematic diagram of the upper bevel-cut casing;

[0023] Figure 8 It is a schematic diagram of the structure of a cylindrical rod and a clamping bolt;

[0024] Fig. 9 It is a structural schematic diagram of the striking base;

[0025] Fig.10 This is a view of the other side of the striking base;

[0026] Fig.11 It is the relationship curve of different circumferences of the crack-free specimen;

[0027] Fig.12 It is the strength envelope of the crack-free specimen;

[0028] Fig.13 This is the CT scan of the cracked specimen;

[0029] Fig.14 The stress-strain relationship curve of the cracked specimen under different confining pressures;

[0030] Fig.15 Strength envelope for cracked specimens;

[0031] In the figure: 1-nut; 2-guard column; 3-upper guard ring base; 4-permeable plastic plate; 5-filter paper; 6-upper beveled casing; 7-beveled surface; 8-lower beveled casing; 9-sampling base; 10-bolt; 11-lower guard ring base; 12-pin shaft; 13-tightening bolt; 14-cylindrical rod; 15-sliding hole; 16-gasket; 17-pore pressure test channel; 18-water and air guiding channel; 19-L-shaped arc sleeve; 20-cylinder; 21-clamping hole; 22-clamp; 23-cylindrical casing; 24-threaded hole; 25-groove; 26-bolt hole. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0033] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0034] The utility model provides a sample preparation device suitable for CT scanning fissure soil triaxial test, such as Figure 1 to Figure 4 , including: a lower beveled casing 8, an upper beveled casing 6 and a fixing assembly, the top of the lower beveled casing 8 has an inclined beveled surface 7, the bottom of the upper beveled casing 6 has an inclined beveled surface 7, the lower beveled casing 8 and the upper beveled casing 6 can form a cylindrical casing 23 after being connected, and the fixing assembly can fix the lower beveled casing 8 and the upper beveled casing 6; the lower beveled casing 8 and the upper beveled casing 6 are both made of plastic.

[0035] The cylindrical casing 23 in the utility model is composed of two separate parts, namely, a lower beveled casing 8 and an upper beveled casing 6, which is convenient for sample removal and sample loading. When making cracks, only the upper beveled casing 6 is removed and a geotechnical knife is used to make the soil sample bevel surface 7 and the cracks, thereby realizing the production of cracked soil samples. In addition, the lower beveled casing 8 and the upper beveled casing 6 are both made of plastic and can be suitable for CT scanning.

[0036] Among them, Figure 6 to Figure 10As shown, the fixing assembly includes an upper guard ring base 3, a lower guard ring base 11 and a plurality of guard posts 2, a lower beveled guard tube 8 and an upper beveled guard tube 6 are arranged between the upper guard ring base 3 and the lower guard ring base 11, and pairs of ear plates are fixedly arranged on the circumferential edges of the upper guard ring base 3 and the lower guard ring base 11, and a mounting groove is formed between each pair of ear plates, and the mounting grooves on the upper guard ring base 3 and the lower guard ring base 11 correspond to each other, and the bottom of the guard post 2 is hingedly connected to the mounting groove at the bottom, and the part of the guard post 2 near the top is provided with a thread, and the top of the guard post 2 can be threadedly connected to the nut 1 by rotating the guard post 2, and the nut 1 is preferably a ram nut. When in use, after assembly, the nut 1 is screwed onto the guard post 2, and the nut 1 can press the ear plate on the upper guard ring base 3 to fix the upper guard ring base 3 and the lower guard ring base 11.

[0037] In some embodiments, in order to adapt to the triaxial instrument, the embodiments of the utility model also include a sampling base 9, which is arranged between the lower guard ring base 11 and the lower beveled casing 8. The sampling base 9 is provided with a pore pressure test channel 17 and a water and air channel 18 that pass through the upper and lower surfaces. A clamping hole 21 that is recessed inward to a certain depth and matches the bottom rod of the triaxial instrument is provided at the center of the lower surface. During the test, the bottom rod of the triaxial instrument is embedded in the clamping hole 21 at the bottom of the sampling base 9 to become the triaxial instrument sample bearing base.

[0038] Specifically, the striking base 9 includes a cylinder 20 and a three-opening L-shaped arc sleeve 19. A circle of grooves 25 is provided on the outer edge of the upper surface of the cylinder 20. Three bolt holes 26 are evenly distributed along the circumferential direction on the outer side of the upper part of the cylinder 20, corresponding to the three L-shaped arc sleeves 19 respectively. During the test, the top of the cylinder 20 is used to bind the rubber film.

[0039] In some embodiments, the lower beveled casing 8 and the upper beveled casing 6 are provided with oppositely arranged sliding holes 15, in which the cylindrical rod 14 is inserted, and a plurality of threaded holes 24 are arranged at a certain interval outside each sliding hole 15, in which the clamping bolt 13 is inserted, and the clamping bolt 13 can extend into the sliding hole 15 and clamp and fix the cylindrical rod 14. In a more preferred embodiment, the cylindrical rod 14 has a scale along its length direction.

[0040] Specifically, rotating the clamping bolt 13 can screw the screw into the sliding hole 15 , and then abut against the side wall of the cylindrical rod 14 to fix the cylindrical rod 14 .

[0041] In some embodiments, a water-permeable plastic plate 4 and filter paper 5 are further included. During production, the bottom and top of the soil in the cylindrical casing 23 are both paved with the water-permeable plastic plate 4 and filter paper 5. The water-permeable plastic plate 4 is specifically a water-permeable plastic circular plate.

[0042] In some embodiments, such as Figure 5As shown, it also includes a pad, which is used to pad the bottom of the soil in the lower bevel casing 8, and the pad has various thicknesses.

[0043] In some embodiments, the upper and lower beveled protective sleeves may be fixed together by buckles or other components. When buckles are used, buckle holes need to be provided at positions where the upper and lower beveled protective sleeves are close to each other.

[0044] The utility model is suitable for the use of the CT scanning fissured soil triaxial test sample preparation device.

[0045] Step 1, sample preparation: fix three L-shaped sleeves on the sample striking base 9, embed the sample striking base 9 on the lower retaining ring base 11, insert the cylindrical rod 14 into the sliding hole 15 of the lower beveled casing 8, and then align the sliding hole 15 on the elliptical beveled surface 7 of the upper beveled casing 6 with the cylindrical rod 14 and insert it, and then fasten the upper and lower beveled casings through the buckles 22 at both ends of the long diameter of the elliptical beveled surface 7, so that the upper and lower beveled casings are connected as a whole;

[0046] Step 2. Place a permeable plastic circular plate on the sample striking base 9, and cover it with a circular filter paper 5. Then place the cylindrical casing 23 into the L-shaped arc sleeve 19 of the sample striking base 9. According to the provisions of GB / T50123-2019, the prepared soil material is divided into five layers and compacted into a cylindrical soil sample in the beveled cylindrical casing 23. The surface is leveled, and the filter paper 5 and the permeable plastic circular plate are added. The upper guard ring base 3 is covered on the cylindrical casing 23, and the three guard columns 2 are pressed into the installation groove and tightened with ram nut.

[0047] Step 3. Preparation method when the crack is located at the edge of the sample: After preparing the cylindrical sample 20, open the buckle 22 to separate the upper and lower beveled casings, and control the distance between the upper and lower beveled casings by adjusting the height of the cylindrical rod 14. This distance is the thickness of the crack. Then, the soil at the edge of the sample is dug out through the gap between the upper and lower beveled casings to form a crack of the corresponding shape. After completion, return the cylindrical rod 14 to its original state and close the upper and lower beveled casings.

[0048] Among them, the elliptical bevel 7 is designed according to the inclination angle of the crack, so the inclination angle of the bevel 7 is consistent with the inclination angle of the crack. According to the designed crack occurrence, sliding holes 15 are arranged at different positions to avoid the cylindrical rod 14 in the sliding hole 15 blocking the production of cracks at corresponding positions. The cylindrical rod 14 can be arranged in the sliding holes 15 at different positions, and the radial depth of the geotechnical knife cutting along the elliptical bevel 7 can be limited by relying on the supporting effect of the cylindrical rod 14, so as to adapt to the production of cracks of different shapes. In addition, the thickness requirement of the crack can be achieved by moving the cylindrical rod 14 upward.

[0049] Preparation method when the crack is located in the middle of the sample: after the cylindrical sample 20 is prepared, open the buckle 22 to separate the upper and lower bevel casings, take out the cylindrical rod 14 in the upper bevel casing 6 and the lower bevel casing 8, use a geotechnical knife to cut the cylindrical sample 20 into two parts along the elliptical bevel surface 7, take out the upper sample and put it into the upper bevel casing 6, put a gasket 16 at the bottom of the lower sample (the thickness of the selected gasket is consistent with the thickness of the crack to be made), the thickness of the gasket 16 is consistent with the thickness of the crack, Use a geotechnical knife to cut a crack in the middle of the upper surface of the lower sample according to the shape and thickness of the crack. For cracks with fillers, fill the fillers into the cracks. For unfilled cracks, just scrape the area around the cracks. Then shave the non-crack areas on the upper surface of the lower sample and the lower surface of the upper sample, remove the gasket 16 at the bottom of the sample, squeeze the two parts of the sample into one, add an appropriate amount of soil, and then compact it with a hammer. Pay attention to ensuring that the height of the sample remains unchanged, buckle the upper and lower beveled casings into one, and fix the entire device with a fixing assembly.

[0050] Step 4: Take the entire device of the prepared sample to a CT scanner for scanning. Since the lower beveled casing 8 and the upper beveled casing 6 are made of plastic, they are light in weight, and X-rays can penetrate them effectively, producing few or no artifacts. They can quantitatively obtain the microscopic information of the cracks, check whether the cracks of the prepared sample are consistent with the design requirements, and further study the properties of the fractured soil.

[0051] Step 5: Put the scanned sample and the device into the vacuum cylinder for saturation and exhaust, remove the peripheral fixing components, insert the bottom rod of the triaxial instrument into the lower clamping hole 21 of the sample base 9, and then remove the L-shaped arc sleeve 19 of the sample base 9. Wrap the sample with the rubber film with the film tube. The lower part of the rubber film is tied to the cylinder 20, and the upper part is tied to the triaxial instrument sample cap. At the same time, the pore pressure test channel 17 of the cylinder 20 of the sample base 9 is connected to the pore pressure conduit of the triaxial instrument, and the water and air channel 18 is connected to the water and air conduit of the triaxial instrument. After the sample is installed, start the triaxial compression test in accordance with the provisions of GB / T 50123-2019 to obtain the failure form and stress-strain relationship curve of the fissured soil.

[0052] Step 6, preparation method for cracks located on the side of the sample: after preparing the cylindrical sample 20, open the buckle 22 to allow the upper beveled casing 6 to move upward, adjust the cylindrical rod 14 to move upward a certain distance, which is consistent with the thickness of the crack, and then fix the cylindrical rod 14 with the clamping bolt 13, pad the bottom of the sample with a gasket 16 that is consistent with the thickness of the crack, and cut from the outside of the cylindrical sample 20 along the upper and lower elliptical beveled surfaces 7 with a geotechnical knife or a hacksaw according to the designed crack occurrence, and prepare cracks with a certain inclination, thickness and penetration rate. For cracks with fillers, fill the fillers into the cracks. For cracks without fillers, just scrape the cracks flat, then remove the gasket 16 at the bottom of the sample, pull out the clamping bolt 13, let the cylindrical rod 14 return to the bottom of the round hole, buckle the upper and lower beveled casings together, and fix the entire device with a fixing assembly;

[0053] Repeat steps four and five.

[0054] like Fig.11 It is the relationship curve of different circumferences of crack-free specimens.

[0055] like Fig.12 It is the strength envelope of crack-free specimen.

[0056] like Fig.13 This is a CT scan of a cracked specimen.

[0057] like Fig.14 The stress-strain relationship curve of cracked specimens under different confining pressures.

[0058] like Fig.15 Strength envelope for cracked specimens.

[0059] The present invention uses specific examples to illustrate the principle and implementation of the present invention. The above examples are only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A sample preparation device suitable for CT scanning triaxial test of fissured soil, Features: include: A lower beveled casing, an upper beveled casing and a fixing assembly, wherein the top of the lower beveled casing is provided with an inclined beveled surface, the bottom of the upper beveled casing is provided with an inclined beveled surface, the lower beveled casing and the upper beveled casing can form a cylindrical casing after being butted together, and the fixing assembly can fix the lower beveled casing and the upper beveled casing; the lower beveled casing and the upper beveled casing are both made of plastic.

2. The sample preparation device suitable for CT scanning fissured soil triaxial test according to claim 1, Features: The fixing assembly comprises an upper guard ring base, a lower guard ring base and a plurality of guard posts, the lower beveled guard tube and the upper beveled guard tube are arranged between the upper guard ring base and the lower guard ring base, a pair of ear plates are fixedly arranged on the circumferential edges of the upper guard ring base and the lower guard ring base, a mounting groove is formed between each pair of ear plates, the mounting grooves on the upper guard ring base and the lower guard ring base correspond to each other one by one, the bottom of the guard post is hingedly connected to the mounting groove at the bottom, the portion of the guard post close to the top is provided with a thread, and rotating the guard post can make the top of the guard post enter the mounting groove at the top, and the top of the guard post can be threadedly connected to a nut.

3. The sample preparation device suitable for CT scanning fissured soil triaxial test according to claim 2, Features: The beveled surfaces of the lower beveled protective tube and the upper beveled protective tube are provided with sliding holes arranged opposite to each other, and the cylindrical rods are inserted into the sliding holes. A plurality of threaded holes are arranged at a certain interval on the outside of each sliding hole, and clamping bolts are inserted into the threaded holes. The clamping bolts can extend into the sliding holes and clamp and fix the cylindrical rods.

4. The sample preparation device suitable for CT scanning fissured soil triaxial test according to claim 3, Features: The cylindrical rod has scales along its length direction.

5. The sample preparation device suitable for CT scanning fissured soil triaxial test according to claim 2, Features: It also includes a sampling base, which is arranged between the lower guard ring base and the lower beveled casing. The sampling base is provided with a pore pressure test channel and a water and air guide channel that pass through the upper and lower surfaces. A clamping hole that is recessed inward to a certain depth and matches the bottom rod of the triaxial instrument is provided at the center of the lower surface.

6. The sample preparation device for triaxial test of CT scanning fissured soil according to claim 5, Features: The striking base includes a cylinder and a three-opening L-shaped arc sleeve. A circle of grooves is provided on the outer edge of the upper surface of the cylinder. Three bolt holes are evenly distributed along the circumferential direction on the outer side of the upper part of the cylinder, corresponding to the three L-shaped arc sleeves respectively. During the test, the top of the cylinder is used to bind the rubber film.

7. The sample preparation device for triaxial test of CT scanning fissured soil according to claim 1, Features: It also includes a water-permeable plastic plate and filter paper. During production, the bottom and top of the soil in the cylindrical casing are both paved with the water-permeable plastic plate and the filter paper.

8. The sample preparation device suitable for CT scanning fissured soil triaxial test according to claim 1, Features: It also includes a pad, which is used to pad the bottom of the soil in the lower bevel casing.

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