A true triaxial sample preparation method for soft and broken rock core

Abstract

A true triaxial sample preparation device and method for soft and broken rock core belong to the technical field of rock mass engineering, and the sample preparation device comprises a numerical control wire cutting machine tool with a cold gas nozzle. The numerical control wire cutting machine tool is connected with a core clamping assembly. The core clamping assembly comprises end frames with end pressure bearing columns. Four side pressure bearing columns are connected between the end frames. End surrounding plates and side surrounding plates are respectively connected to the end pressure bearing columns and the side pressure bearing columns. The sample preparation method comprises six steps of installing and clamping the to-be-cut rock core, rotating and fixing the core clamping assembly to 45° orientation, cutting the two ends of the to-be-cut rock core respectively, rotating and fixing the core clamping assembly to 0° orientation, cutting the four sides of the to-be-cut rock core to form a square sample, and taking out the square sample. The to-be-cut rock core can be clamped during the whole cutting process, and the opening of the rock core structure surface is avoided. At the same time, water is not needed in the sample preparation process, and the damage of water to the soft and broken rock is avoided.

Description

Technical Field

[0001] This invention belongs to the field of rock mass engineering technology and relates to a sample preparation method, particularly a true triaxial sample preparation method for weak and fractured rock cores. Background Technology

[0002] Weak and fractured rock masses have always been an important topic in engineering geology and rock mechanics research. In mining engineering, water conservancy and hydropower engineering, tunnel engineering, and other fields, weak surrounding rock is common, frequently causing severe geological disasters such as collapses and large deformations during excavation. Therefore, conducting relevant experiments to understand the mechanical properties and failure mechanisms of weak and fractured rock masses is extremely important for more reliable assessment of their engineering stability.

[0003] Soft and fractured rock masses are characterized by their weakness, looseness, fracturing, and expansion. They are prone to mudification and disintegration when exposed to water, and exhibit well-developed structural planes, such as mudstone, shale, siltstone, and fractured zones. Currently, most rock cutting and sampling devices are large rock cutting machines, capable of cutting intact hard rock. However, for soft and fractured rocks, the cutting process causes significant damage and disturbance, primarily due to the water and vibration involved. This easily leads to the disintegration of soft and fractured rocks, the detachment of fragments, and the inability to obtain samples. In recent years, wire cutting machines have been used to cut rocks, reducing disturbance. However, water is still used to cool the diamond wire, making it unsuitable for some soft rocks. Furthermore, the inherent incompleteness of fractured rocks makes them unsuitable for processing.

[0004] Therefore, there is an urgent need for a sample preparation method suitable for weak and fractured rock cores to ensure the success of sample preparation for weak and fractured rocks. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a true triaxial sample preparation method for weak and fractured rock cores, which solves the technical problem that the rock core is greatly disturbed and damaged during the preparation of weak and fractured rock cores, resulting in a low success rate of sample preparation.

[0006] To achieve the above and other related objectives, this invention provides a method for preparing true triaxial samples from weak and fractured rock cores, comprising the following steps:

[0007] Step 1: Install the core to be cut between the end plate and the side plate, and clamp the core.

[0008] Step 2: Rotate the core clamping assembly to a 45° position and place it on the fixed base, then fix the end frame to the fixed base;

[0009] Step 3: Cut the two ends of the core sample. The method for cutting the ends of the core sample is as follows:

[0010] 1) adjust the cutting line into the core clamping assembly and clamp the core;

[0011] 2) adjust the worktable of the numerical control wire cutting machine tool, make the cutting line close to the end face of the side panel, and then start the numerical control wire cutting machine tool to make the front and back direction work to cut the end;

[0012] 3) take out the excess core after cutting, and clamp the end panel again;

[0013] 4) move the cutting line out of the core clamping assembly;

[0014] 5) adjust the worktable of the numerical control wire cutting machine tool, make the other end of the end frame close to the cutting line;

[0015] 6) repeat steps 1), 2), 3), 4) to cut the other end of the core;

[0016] Step four, loosen the locking nut, rotate the core clamping assembly to 0° orientation, and fix it on the fixed base;

[0017] Step five, cut the four sides of the core respectively to form a square sample, and the specific cutting method is:

[0018] 1) adjust the cutting line into the core clamping assembly and clamp the core;

[0019] 2) adjust the worktable of the numerical control wire cutting machine tool, make the cutting line close to the side of the upper and lower side panels, and then start the numerical control wire cutting machine tool to make the left and right direction work to cut the side;

[0020] 3) move the cutting line out of the core clamping assembly;

[0021] 4) loosen the locking nut, and rotate the core clamping assembly along its axis by 90° and fix it on the worktable of the numerical control wire cutting machine tool;

[0022] 5) repeat steps 1), 2), 3), 4) to complete the cutting of the remaining three sides and form a square sample;

[0023] Step six, take out the square sample.

[0024] In any of the above schemes, preferably, in step one, the installation and clamping of the core to be cut comprises the following steps:

[0025] Step 1, remove the end frame at one end, loosen the fastening bolt group of the side and the other end, and make the four side panels and the end panel at the other end exit;

[0026] Step 2, the core to be cut is inserted between the four side face plates, and then the removed end frame is installed, while the end pressure column and the side pressure column are fastened, so that the end face plate and the side face plate are in contact with the core to be cut and the core to be cut is clamped.

[0027] Preferably in any of the above solutions, the specific method of clamping the core after the cutting line is adjusted into the core clamping assembly and moving the cutting line out of the core clamping assembly in the step three comprises the following steps:

[0028] Step 1, the end fixing bolts on the two side pressure columns near the cutting line are loosened, and the fastening bolt set on the two side pressure columns is loosened, and the two side pressure columns are pushed out 1-3mm along the axis thereof;

[0029] Step 2, the workbench is adjusted so that the cutting line passes through the gap between the side pressure column and the end frame and then enters or moves into the core clamping assembly;

[0030] Step 3, the two side pressure columns are reset and fixed by the end fixing bolts;

[0031] Step 4, the fastening bolt set is adjusted to clamp the core to be cut.

[0032] Preferably in any of the above solutions, the specific method of clamping the core after the cutting line is adjusted into the core clamping assembly and moving the cutting line out of the core clamping assembly in the step five comprises the following steps:

[0033] Step 1, the end fixing bolts on one side pressure column near the cutting line are loosened, and the fastening bolt set on the side pressure column is loosened, and the side pressure column is pushed out 1-3mm along the axis thereof;

[0034] Step 2, the workbench is adjusted so that the cutting line passes through the gap between the side pressure column and the end frame and then enters or moves into the core clamping assembly;

[0035] Step 3, the side pressure column is reset and fixed by the end fixing bolts;

[0036] Step 4, the fastening bolt set is adjusted to clamp the core to be cut.

[0037] As described above, the soft and broken core true triaxial sample preparation method has the following beneficial effects:

[0038] 1, in the application, the core clamping assembly clamps the core to be cut during the whole cutting process, the clamping effect is good, the fixing stability is high, the structure surface of the core is prevented from being opened and the new structure surface caused by cutting is prevented, the stability of the sample preparation process is effectively improved, and the quality of the prepared sample is improved.

[0039] 2. In this invention, the cutting line is cooled by cooling gas using an air pump, avoiding the use of water. This prevents water from damaging the soft and broken rock, reduces the difficulty of sample preparation, and effectively improves the efficiency and quality of the prepared samples.

[0040] 3. In this invention, wire cutting technology is used, which reduces the disturbance to the rock during the cutting process, thereby effectively improving the quality of the prepared sample. Attached Figure Description

[0041] Figure 1 The diagram shown is a schematic representation of the structure of the present invention.

[0042] Figure 2 The diagram shows the structure of the core clamping assembly.

[0043] Figure 3 The diagram shown is of the side panel.

[0044] Figure 4 A schematic diagram showing the end panel.

[0045] Figure 5 This is a diagram showing the cutting path of the remaining material at the end of the core sample.

[0046] Figure 6 This shows the cutting path of the leftover material on the side of the core sample.

[0047] Figure 7 The image shows a schematic diagram of a weak, broken specimen after it has been cut and shaped.

[0048] Figure 8 This is a schematic diagram of the cutting process for a weak and fractured rock core.

[0049] Component designation explanation

[0050] 1-Control box; 2-Machine bed; 3-Worktable; 4-Front-back support plate; 5-Left-right support plate; 6-Wire feeding mechanism; 7-Cold air nozzle; 8-Cutting line; 9-End frame; 10-Side pressure column; 11-End pressure column; 12-Side panel; 13-End panel; 14-Fastening bolt assembly; 141-Setting screw; 142-Return tie rod; 15-Core to be cut; 16-Base; 17-Pressure plate; 18-Locking nut; 19-End fixing bolt; 20-Threaded rod. Detailed Implementation

[0051] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0052] Please see Figures 1 to 8It is to be understood that the structures, proportions, sizes, etc. shown in the drawings accompanying the present specification are merely intended to facilitate the understanding of the present disclosure for those skilled in the art, and are not intended to limit the scope of the present application, and therefore do not have technical significance. Any modification, change in proportion or adjustment in size that does not affect the effect and purpose of the present application should still fall within the scope of the present disclosure. Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are merely for the convenience of clear description, and are not intended to limit the scope of the present application, and the change or adjustment of the relative relationship without substantial change in technical content is also considered as the scope of the present application.

[0053] Embodiment 1

[0054] The present application provides a kind of soft weak broken core true triaxial sample preparation device, including numerical control wire cutting machine tool, two symmetrically arranged bases 16 are connected on the numerical control wire cutting machine tool, the core clamping assembly is detachably connected on the base 16 by pressing plate 17 and lock nut 18, the core clamping assembly includes oppositely arranged octagonal end frame 9, end pressure column 11 is connected in each of the end frame 9 middle part, four evenly arranged side pressure columns 10 are connected between two end pressure columns 11 by end fixed bolt 19, the opposite surface of two end pressure columns 11 is connected with end fence 13 by fastening bolt group 14, the inner wall of end fence 13 is arc-shaped, the inner surface of four side pressure columns 10 is connected with side fence 12 by fastening bolt group 14, the inner wall of side fence 12 is rectangular, cooling gas nozzle 7 for cooling cutting wire 8 is provided on the numerical control wire cutting machine tool.

[0055] When the present embodiment is used, the sample preparation device includes numerical control wire cutting machine tool for cutting the to-be-cut core 15, and core clamping assembly for clamping and fixing the to-be-cut core 15. Among them,

[0056] The numerical control wire cutting machine tool is composed of a workbench, a wire feeding mechanism 6, a liquid supply system, a control system and the like, and is used for low-disturbance wire cutting processing of the to-be-cut core 15. In the present embodiment, the numerical control wire cutting machine tool adopts a DK7735 type electric spark numerical control wire cutting machine tool, and therefore the workbench, the wire feeding mechanism 6, the liquid supply system and the control system of the numerical control wire cutting machine tool all belong to the prior art. According to the prior art, those skilled in the art can know that the present embodiment will not be further described. Of course, the numerical control wire cutting machine tool is not limited to this type of machine tool, and other machine tools capable of realizing low-disturbance wire cutting can also be used, and those skilled in the art can make appropriate selection according to the situation.

[0057] In this embodiment, the numerical control wire cutting machine is provided with a control box 1, and the working condition of the numerical control wire cutting machine is controlled through the control box 1.

[0058] The core clamping assembly comprises an end frame 9, an end pressure bearing column 11, a side pressure bearing column 10, an end fence 13, a side fence 12 and a fastening bolt set 14, and can clamp the sample in the whole cutting process to avoid scattering. Specifically, the core clamping assembly comprises two symmetrically arranged end frames 9, the middle portions of the two end frames 9 are connected to symmetrically arranged end pressure bearing columns 11, the opposite surfaces of the two end pressure bearing columns 11 are connected to an adjustable end fence 13 through the fastening bolt set 14, and the end fence 13 is used for clamping and fixing the end of the to-be-cut core 15. The opposite surfaces of the two end frames 9 are connected to four uniformly arranged side pressure bearing columns 10 through end fixing bolts 19, and the inner surfaces of the side pressure bearing columns 10 are connected to an adjustable side fence 12 through the fastening bolt set 14, and the side fence 12 is used for clamping and fixing the side of the to-be-cut core 15.

[0059] After the to-be-cut core 15 is clamped and fixed in the core clamping assembly, the core clamping assembly is adjusted to the required position, and then the core clamping assembly is connected to the workbench of the numerical control wire cutting machine through the fixing assembly, so that the to-be-cut core 15 can be conveniently cut.

[0060] In this embodiment, the outer contour of the end frame 9 is a regular octagon, which can be placed at multiple angles, thereby meeting the requirement of cutting the four faces of the to-be-cut core 15 to obtain a cuboid sample.

[0061] In this embodiment, the base 16 is movably connected to the workbench surface 3, a plurality of uniformly arranged threaded holes are formed in the length direction of the base 16, the pressing plate 17 is arranged above the bottom inner edge of the end frame 9, the two ends of the pressing plate 17 protrude out of the end frame 9 and are connected to a threaded rod 20 penetrating through the pressing plate 17, the threaded rod 20 is connected to the threaded holes in the base 16 after penetrating through the pressing plate 17, and the locking nut 18 is arranged on the threaded rod 20 and located above the pressing plate 17. When it is required to fix the core clamping assembly, the locking nut 18 is rotated, the locking nut 18 moves downward in the process and drives the pressing plate 17 to move downward, the pressing plate 17 moves downward in the process and drives the end frame 9 to move downward, and then the end frame 9 is in contact with the base 16 and is fixed on the base 16, and the rotation of the locking nut 18 is stopped. When it is required to loosen the core clamping assembly, the locking nut 18 is rotated in the reverse direction. The plurality of threaded holes arranged in the base 16 can facilitate the adjustment of the position of the core clamping assembly on the base 16, thereby meeting different cutting requirements.

[0062] In this embodiment, in order to avoid the water cooling the cutting line 8 to cause the weak broken rock to disintegrate and the block stone to fall off and cannot be sampled, the cooling gas is used to cool the cutting line 8 and flush away the rock cutting. Specifically, the end of the wire feeding mechanism 6 is connected with a cooling nozzle for cooling the cutting line 8 on the numerical control wire cutting machine tool, and the cooling nozzle is connected with a gas pump. The cooling gas generated by the gas pump is sprayed to the cutting line 8 through the cooling nozzle to cool the cutting line 8 and flush away the rock cutting.

[0063] In this embodiment, four connecting holes are uniformly arranged on the end frame 9, and the two ends of the side pressure bearing column 10 extend into the connecting holes and are detachably connected through the end fixing bolts 19.

[0064] As a further description of the above embodiment, the fastening bolt set 14 includes a top screw 141, and a return pull rod 142 is symmetrically arranged on both sides of the top screw 141. The top screw 141 and the return pull rod 142 are respectively penetrated through the end pressure bearing column 11 and the side pressure bearing column 10 and are fixedly connected with the corresponding end coaming 13 and side coaming 12. The return pull rod 142 is externally sleeved with a spring 143, and the two ends of the spring 143 are respectively connected with the pressure bearing column and the nut.

[0065] When the present embodiment is used, the fastening bolt set 14 is used to push the side coaming 12 and the end coaming 13 to clamp the rock core. The fastening bolt set 14 includes the top screw 141, and the top screw 141 is arranged at the middle part of the end pressure bearing column 11 and the side pressure bearing column 10. The return pull rod 142 is symmetrically arranged about the center of the top screw 141, so as to ensure that the fastening bolt set 14 can uniformly apply force to the end coaming 13 and the side coaming 12, and the end coaming 13 and the side coaming 12 can stably move, so as to stably clamp and fix the rock core to be cut 15, and avoid that the end coaming 13 and the side coaming 12 are unevenly stressed and are tilted to be stuck during the moving process or cannot effectively adhere to the rock core to be cut 15, thereby affecting the clamping and fixing effect of the rock core to be cut 15.

[0066] In this embodiment, the return pull rod 142 plays a passive adjusting role, and the spring 143 is arranged between the return pull rod 142 and the nut outside the pressure bearing column. The top screw 141 is arranged between the two return pull rods 142 and plays an active adjusting role. When the top screw 141 is screwed, the spring 143 of the return pull rod 142 is compressed, and the sample is clamped; when the top screw 141 is loosened, the spring 143 of the return pull rod 142 rebounds, and the sample is released.

[0067] As a further description of the above embodiment, the length of the side coaming 12 is equal to the length of the sample after cutting, and the width of the side coaming 12 is equal to the width or height of the sample after cutting. The length of the end coaming 13 is equal to the width of the sample after cutting, and the width of the end coaming 13 is equal to the height of the sample after cutting.

[0068] In use of the embodiment, the sizes of the side panels 12 and the end panels 13 of the core clamping device can be replaced according to the size of the core. The inner wall of the side panel 12 is in the shape of a circular arc, and the radius of the arc is determined according to the diameter of the drilled core, which is suitable for cores of different diameters. The length of the side panel 12 is equal to the length of the cut sample, and the width of the side panel 12 is equal to the width or height of the cut sample (if the width and height of the sample are equal, the four side panels 12 are of the same size; if the width and height of the sample are not equal, the four side panels 12 are of the same size in pairs). The end panel 13 is in the shape of a cuboid, and the length of the surface in contact with the core is equal to the width of the cut sample, and the width of the end panel 13 is equal to the height of the cut sample.

[0069] As a further description of the above embodiment, the numerical control wire cutting machine tool comprises a workbench, a wire feeding mechanism 6, a liquid supply system, and a control system. The workbench comprises left and right direction supporting plates 5, front and rear direction supporting plates 4 arranged on the left and right direction supporting plates 5, and a workbench surface 3 arranged on the front and rear direction supporting plates 4. The front and rear direction supporting plates 4 and the left and right direction supporting plates 5 are movable.

[0070] In use of the embodiment, the workbench surface 3 is used to install the core clamping assembly and the core to be cut 15. The movable left and right direction supporting plates 5 and the front and rear direction supporting plates 4 can facilitate the movement of the workbench surface 3 in the front and rear directions and the left and right directions, thereby meeting the use requirements.

[0071] In the embodiment, two symmetrically arranged connecting plates are connected above the workbench surface 3. A groove is formed in the upper surface of each connecting plate along the length direction thereof. A boss is arranged below the base 16 and matches the groove. Threaded holes are arranged on the side surface of each connecting plate. After the threaded holes are passed through by bolts, the base 16 is fixed, so that the position of the base 16 is fixed. When the base 16 needs to be moved, the bolts are loosened, and the base 16 can be moved.

[0072] Embodiment 2

[0073] A true triaxial sample preparation method for soft and broken cores, characterized by comprising the following steps:

[0074] Step one, install the core to be cut 15 between the end panel 13 and the side panel 12, and clamp the core, the specific method is as follows:

[0075] Step 1, remove the end frame 9 at one end, loosen the fastening bolt set 14 at the side and the other end, and remove the four side panels 12 and the end panel 13 at the other end;

[0076] Step 2, insert the core 15 to be cut between the four side panels 12 from the end of the removed end frame 9, then install the removed end frame 9, at the same time, tighten the end pressure column 11 and the side pressure column 10, so that the end panel 13 and the side panel 12 are in contact with the core 15 to be cut, and the core 15 to be cut is clamped.

[0077] In step 1, the method for removing the end frame 9 at one end is to loosen the end fixing bolt 19, separate the side pressure column 10 from the end frame 9, and pull out the end frame 9 outward.

[0078] The method for loosening the fastening bolt set 14 is to unscrew the top screw 141, which drives the spring 143 of the return pull rod 142 to rebound, drives the return pull rod 142 to move outward, and thus drives the side panel 12 and the end panel 13 connected with the return pull rod 142 to move outward and exit.

[0079] The method for tightening the end pressure column 11 and the side pressure column 10 is to tighten the top screw 141, which drives the spring 143 of the return pull rod 142 to compress, drives the return pull rod 142 to move inward, and thus the side panel 12 and the end panel 13 move inward to contact the core 15 to be cut and clamp the core 15 to be cut.

[0080] Step 2, place the core clamping assembly on the fixed base 16 after rotating it to a 45° orientation, and fix the end frame 9 on the fixed base 16, which is specifically:

[0081] After rotating the end frame 9 so that the line connecting the upper and lower side pressure plates 17 and the cutting line 8 forms a 45° angle (i.e. 45° orientation), fix the end frame 9 on the fixed base 16. The fixing method of the end frame 9 is to rotate the locking nut 18 downward, which drives the pressure plate 17 to move downward, and the pressure plate 17 drives the end frame 9 to move downward, so that the end frame 9 contacts the fixed base 16 to fix the end frame 9 on the fixed base 16.

[0082] Step 3, cut the two ends of the core respectively, and the method for cutting the ends of the core is:

[0083] 1) Adjust the cutting line 8 to enter the core clamping assembly and clamp the core, which includes the following steps:

[0084] Step 1, adjust the workbench position of the numerical control line cutting machine tool to be close to the end of the core 15 to be cut near the cutting line 8, loosen the end fixing bolt 19 on the two side pressure columns 10 near the cutting line 8, loosen the fastening bolt set 14 on the two side pressure columns 10, and push the two side pressure columns 10 outward along their axes by 2mm;

[0085] Step 2, adjust the workbench by the left and right direction supporting plate 5 and the front and back direction supporting plate 4, so that the cutting line 8 passes through the gap between the side pressure column 10 and the end frame 9 and then enters into the core clamping assembly;

[0086] Step 3, reset the two side pressure columns 10 and fix them by the end fixing bolt 19;

[0087] Step 4, adjust the fastening bolt group 14 to clamp the core 15 to be cut.

[0088] 2) Adjust the workbench of the numerical control wire cutting machine tool, so that the cutting line 8 is close to the end face of the side surrounding plate 12, and then start the numerical control wire cutting machine tool to cut the end, that is, cut along the dotted line direction; Figure 5

[0089] 3) Take out the cut end core excess material, and clamp the end surrounding plate 13 again;

[0090] The end of the core 15 to be cut is irregular and uneven, and the end of the end surrounding plate 13 of the core clamping assembly in contact with the core 15 to be cut is a plane. Therefore, in order to facilitate the clamping of the end surrounding plate 13 and improve the clamping effect, the end surrounding plate 13 is clamped again after the end core excess material after cutting is taken out.

[0091] 4) Move the cutting line 8 out of the core clamping assembly, which includes the following steps:

[0092] Step 1, loosen the end fixing bolt 19 on the two side pressure columns 10 close to the cutting line 8, loosen the fastening bolt group 14 on the two side pressure columns 10, and push the two side pressure columns 10 outward along the axis by 2mm;

[0093] Step 2, adjust the workbench by the left and right direction supporting plate 5 and the front and back direction supporting plate 4, so that the cutting line 8 passes through the gap between the side pressure column 10 and the end frame 9 and then exits to the outside of the core clamping assembly;

[0094] Step 3, reset the two side pressure columns 10 and fix them by the end fixing bolt 19;

[0095] Step 4, adjust the fastening bolt group 14 to clamp the core 15 to be cut

[0096] 5) Adjust the workbench of the numerical control wire cutting machine tool, so that the other end of the end frame 9 is close to the cutting line 8;

[0097] 6) Repeat steps 1), 2), 3), and 4) to cut the other end core excess material;

[0098] ​Step four, loosen the locking nut 18, rotate the core clamping assembly to 0° orientation and fix it on the fixed base 16, specifically,

[0099] Turn the locking nut 18 upward to loosen it, so that the end frame 9 is separated from the fixed base 16, facilitating the adjustment of the end frame 9. After the end frame 9 is separated from the fixed base 16, rotate the end frame 9 so that the connecting line of the upper and lower side plates 17 is parallel to the cutting line 8 (i.e. 0° orientation), and then fix the end frame 9 on the fixed base 16, facilitating the side cutting of the to-be-cut core 15.

[0100] Step five, cut the four sides of the core respectively to form a square sample, and the specific cutting method is as follows:

[0101] 1) Adjust the cutting line 8 to enter the core clamping assembly and clamp the core, including the following steps,

[0102] Step 1, adjust the workbench position of the numerical control wire cutting machine tool to make the cutting line 8 close to one end of the to-be-cut core 3, loosen the end fixed bolt 19 on one side of the side pressure column 10 close to the cutting line 8, loosen the fastening bolt set 14 on this side pressure column 10, and push this side pressure column 10 outward along its axis by 2mm;

[0103] Step 2, adjust the workbench through the left and right direction supporting plate 5 and the front and rear direction supporting plate 4 to make the cutting line 8 pass through the gap between the side pressure column 10 and the end frame 9 and enter the core clamping assembly;

[0104] Step 3, reset this side pressure column 10 and fix it through the end fixed bolt 19;

[0105] Step 4, adjust the fastening bolt set 14 to clamp the to-be-cut core 15.

[0106] 2) Adjust the workbench of the numerical control wire cutting machine tool to make the cutting line 8 close to the side of the upper and lower side surrounding plate 12, and then start the numerical control wire cutting machine tool to make the left and right direction work for side cutting, i.e. cutting along the dotted line direction of Figure 6 ;

[0107] During this process, the remaining material after cutting is not taken out. The inner wall of the side surrounding plate 12 of the core clamping assembly is curved, and the curvature is determined according to the diameter of the to-be-cut core 15, so that the cut part is not taken out, and the clamping effect is better. Because if it is taken out, the side of the sample is a plane, the contact surface between the side surrounding plate 12 and the to-be-cut core 15 is a curved surface, and the clamping effect is not good.

[0108] 3) Move the cutting line 8 out of the core clamping assembly, including the following steps,

[0109] Step 1, loosen the end fixing bolt 19 on one side of the side pressure column 10 near the cutting line 8, loosen the fastening bolt group 14 on the side pressure column 10, and push the side pressure column 10 outwards along its axis by 2mm;

[0110] Step 2, adjust the workbench through the left-right direction supporting plate 5 and the front-rear direction supporting plate 4 to make the cutting line 8 pass through the gap between the side pressure column 10 and the end frame 9 and then move out to the outside of the core clamping assembly;

[0111] Step 3, reset the side pressure column 10 and fix it through the end fixing bolt 19;

[0112] Step 4, adjust the fastening bolt group 14 to clamp the core to be cut 15.

[0113] 4) loosen the locking nut 18, and rotate the core clamping assembly by 90° along its axis and fix it on the workbench of the numerical control wire cutting machine tool;

[0114] 5) repeat steps 1), 2), 3), and 4) to complete the cutting of the remaining three sides to form a square sample;

[0115] Step six, remove the square sample. The method for removing the square sample is as follows: loosen the locking nut 18, remove the pressing plate 17, remove the core clamping assembly from the workbench, remove the end frame 9 and the side pressure column 10 in sequence, and then remove the square sample.

[0116] In summary, the present application can clamp the core to be cut during the whole cutting process, avoids the opening of the core structure surface, at the same time, the sample preparation process does not need water, avoids the damage of water to the weak broken rock, has high sample preparation efficiency and good sample quality. Therefore, the present application effectively overcomes the various shortcomings in the prior art and has high industrial utilization value.

[0117] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for preparing a true triaxial test sample of a weak and fractured rock core, characterized by: The application discloses a true triaxial sample preparation device and a sample preparation method. The sample preparation device comprises a numerical control wire cutting machine tool, two symmetrically arranged bases (16) are connected to the numerical control wire cutting machine tool, a core clamping assembly is detachably connected to the bases (16) through a pressing plate (17) and a locking nut (18), the core clamping assembly comprises oppositely arranged positive octagonal end frames (9), an end pressure bearing column (11) is connected to the middle of each end frame (9), four uniformly arranged side pressure bearing columns (10) are connected between the two end frames (9) through end fixing bolts (19), the opposite faces of the two end pressure bearing columns (11) are connected with end surrounding plates (13) through a fastening bolt set (14), and the inner surfaces of the four side pressure bearing columns (10) are connected with side surrounding plates (12) through the fastening bolt set (14). The sample preparation method comprises the following steps: Step one, install the to-be-cut core (15) between the end surrounding plates (13) and the side surrounding plates (12) and clamp the core, the inner wall of the side surrounding plate (12) is in a circular arc shape, and the width of the side surrounding plate (12) is equal to the width or height of the cut sample; Step two, rotate the core clamping assembly to 45° orientation and place it on the fixed base (16), and fix the end frame (9) on the fixed base (16); Step three, cut the two ends of the to-be-cut core (15) respectively, and the core end cutting method is as follows: 1) adjust the cutting wire (8) to enter the core clamping assembly and clamp the core; 2) adjust the workbench of the numerical control wire cutting machine tool so that the cutting wire (8) is close to the end face of the side surrounding plate (12), and then start the numerical control wire cutting machine tool to cut the end; 3) take out the excess material of the cut end core, re-clamp the end surrounding plate (13); 4) move the cutting wire (8) out of the core clamping assembly; 5) adjust the workbench of the numerical control wire cutting machine tool so that the other end of the end frame (9) is close to the cutting wire (8); 6) repeat steps 1), 2), 3) and 4) to cut the excess material of the other end core; Step four, loosen the locking nut (18), rotate the core clamping assembly to 0° orientation and fix it on the fixed base (16); Step five, cut the four faces of the to-be-cut core (15) respectively to form a square sample, and the specific cutting method is as follows: 1) adjust the cutting wire (8) to enter the core clamping assembly and clamp the core; 2) adjust the workbench of the numerical control wire cutting machine tool so that the cutting wire (8) is close to the side of the upper and lower side surrounding plates (12), and then start the numerical control wire cutting machine tool to cut the side; 3) move the cutting wire (8) out of the core clamping assembly; 4) loosen the locking nut (18) and rotate the core clamping assembly along the axis by 90° and fix it on the workbench of the numerical control wire cutting machine tool; 5) repeat steps 1), 2), 3) and 4) to complete the cutting of the remaining three sides to form a square sample; 2. The method of making a true triaxial specimen of a weak and fractured rock core according to claim 1, characterized in that: Step six, take out the square sample. In step one, the installation and clamping of the to-be-cut core (15) comprise the following steps: Step 1, remove the end frame (9) of one end, loosen the side and the other end of the fastening bolt group (14), and make the four side walls (12) and the end wall (13) of the other end exit; Step 2, insert the core (15) to be cut into the four side walls (12) from the removed end, then install the removed end frame (9), and at the same time, fasten the end pressure column (11) and the side pressure column (10), so that the end wall (13) and the side wall (12) are in contact with the core (15) to be cut and clamp the core (15) to be cut.

3. The method of making a true triaxial specimen of a weak and fractured rock core according to claim 1, characterized in that: The specific method of adjusting the cutting wire (8) into the core clamping assembly to clamp the core and moving the cutting wire (8) out of the core clamping assembly in steps three and five includes the following steps: Step 1, adjust the position of the workbench of the numerical control wire cutting machine tool, loosen the end fixing bolt (19) on the two side pressure columns (10) near the cutting wire (8), loosen the fastening bolt group (14) on the two side pressure columns (10), and push the two side pressure columns (10) outward along their axes by 1-3mm; Step 2, adjust the workbench so that the cutting wire (8) passes through the gap between the side pressure column (10) and the end frame (9) and enters or moves out of the core clamping assembly; Step 3, reset the two side pressure columns (10) and fix them by the end fixing bolt (19); Step 4, adjust the fastening bolt group (14) to clamp the core (15) to be cut.

4. The method of making a true triaxial specimen of a weak and fractured rock core according to claim 1, characterized in that: The specific method of adjusting the cutting wire (8) into the core clamping assembly to clamp the core and moving the cutting wire (8) out of the core clamping assembly in steps three and five includes the following steps: Step 1, loosen the end fixing bolt (19) on one side of the side pressure column (10) near the cutting wire (8), loosen the fastening bolt group (14) on the side pressure column (10), and push the side pressure column (10) outward along its axis by 1-3mm; Step 2, adjust the workbench so that the cutting wire (8) passes through the gap between the side pressure column (10) and the end frame (9) and enters or moves out of the core clamping assembly; Step 3, reset the side pressure column (10) and fix it by the end fixing bolt (19); Step 4, adjust the fastening bolt group (14) to clamp the core (15) to be cut.

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