Triaxial sample preparation device and method for coarse-grained soil with saturation and transfer sample functions

Abstract

The present application belongs to the technical field of coarse-grained soil mechanical property testing, and particularly relates to a spinning type coarse-grained soil triaxial test sample preparation device with sample saturation and transfer functions, comprising a counterforce frame base, a sample cap and a sample preparation barrel base, the upper end of the counterforce frame base is fixedly connected with a boss, an annular groove is formed in the upper end of the counterforce frame base, four uniformly distributed connecting screw holes are formed in the upper end of the counterforce frame base, a rigid counterforce column is threadedly connected in each connecting screw hole, a rubber membrane is sleeved on the outer side of the boss, and two symmetrically distributed annular water stop clamps are sleeved on the upper and lower ends of the outer side of the rubber membrane. Compared with the traditional scheme, the present scheme greatly reduces the saturation time of the sample by controlling the water inlet valve, the water control valve and the air extraction valve, and realizes rapid saturation; meanwhile, the sample can be conveniently transferred to the triaxial testing machine through the sample lifting hole, the steel wire rope and the lifting beam, and the structure is ingenious and the operation is convenient.

Description

Technical Field

[0001] This invention belongs to the field of mechanical property testing technology for coarse-grained soil, specifically relating to a spinning-type triaxial test sample preparation device and method for coarse-grained soil with saturation and transfer sample functions. Background Technology

[0002] Coarse-grained soil is widely distributed in Northwest my country, and the number of large-scale hydropower projects built on coarse-grained soil foundations or using coarse-grained soil as an engineering material has surged. As a result, the study of the static and dynamic properties of saturated coarse-grained soil in water conservancy projects has become an important aspect of engineering research. When determining the mechanical properties of coarse-grained soil through triaxial testing, loose coarse-grained soil samples are typically taken from the engineering site to a laboratory. The soil is then reshaped using a sample preparation mold into cylinders with a height-to-diameter ratio of 2-2.5, and the sample diameter is equal to or greater than five times the maximum particle size. Therefore, a standard cylindrical sample with a diameter of 200 mm and a height of 450 mm is commonly used. To simulate the mechanical state of coarse-grained soil dam materials under saturation, the prepared samples are usually saturated before triaxial testing. Because coarse-grained soil is a granular material, it is difficult to maintain a fixed shape without external template support. In triaxial tests of coarse-grained soil, the usual practice for sample preparation is to install a sample preparation mold on the base of the triaxial testing machine for coarse-grained soil, and obtain a sample with a relatively uniform overall density consistent with that in actual engineering by means of static and dynamic loads such as manual compaction, measurement, spinning, hydraulic pressure, and vibration. Then, the sample is saturated by the water pressure device of the testing machine itself.

[0003] In existing technologies, due to the large size of triaxial specimens and the relatively high porosity of coarse-grained soil, saturating the soil samples using only a triaxial testing machine's water pump or elevated water tank would be time-consuming. Furthermore, saturation under water head alone may result in uneven or insufficient saturation among the coarse-grained soil specimens. Additionally, triaxial mechanical experiments on coarse-grained soil often require the preparation of multiple specimens for comparison. However, the conventional preparation process for saturated coarse-grained soil triaxial specimens involves layered compaction of the coarse-grained soil and loading and unloading of various components of the specimen preparation device, a relatively complex and time-consuming process. This preparation process can only be performed on a triaxial compression testing machine, thus only one specimen can be prepared at a time, significantly limiting experimental efficiency. Conventional coarse-grained soil triaxial specimens cannot be prepared in multiple specimens under a triaxial compression testing machine and then transferred and transported to the triaxial testing machine for mechanical experiments. Moreover, the degree of disturbance to the coarse-grained soil triaxial specimens during transfer is difficult to control, greatly limiting the speed and quality control of coarse-grained soil triaxial testing. Summary of the Invention

[0004] The purpose of this invention is to provide a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, which solves the problems of slow saturation speed, sample preparation steps limited to triaxial compression testing machine, single sample quantity preparation, inability to transfer coarse-grained soil samples, and inability to accurately control sample density.

[0005] To achieve the above objectives, this invention provides a spin-compression triaxial test sample preparation device for coarse-grained soil with saturation and sample transfer functions, comprising a reaction frame base, a sample cap, and a sample preparation barrel base. The device is characterized in that: a boss is installed at the upper end of the reaction frame base; an annular groove is formed on the reaction frame base; multiple evenly distributed connecting screw holes are formed on the reaction frame base; a rigid reaction column is threaded into the interior of each connecting screw hole; a rubber membrane is sleeved on the outer side of the boss; two symmetrically distributed annular water-stopping clamps are sleeved on the outer side of the rubber membrane; a sample preparation barrel is fixedly connected to the outer side of the sample preparation barrel base; the rubber membrane contacts the sample preparation barrel; a seam is provided on the sample preparation barrel; multiple evenly distributed clamping grooves are fixedly connected to the sample preparation barrel; and clamping bolts are threaded into the interior of each clamping groove.

[0006] Furthermore, the three-lobed circular sample preparation cylinder has a slidingly connected pusher disc inside, and a threaded spinning rod is rotatably connected inside the pusher disc. A reaction frame circular cover plate is threadedly connected to the outside of the threaded spinning rod. The reaction frame circular cover plate has a central bolt hole and multiple evenly distributed connecting bolt holes. Each rigid reaction column has two symmetrically distributed bolt caps threadedly connected to it. The three-lobed circular sample preparation cylinder has two symmetrically distributed permeable plates inside. A sample cap is sleeved inside the upper end of the annular water-stop clamp. An air extraction valve is fixedly connected to one side of the sample cap. An air vent is provided between the center of the sample cap and the air extraction valve.

[0007] Furthermore, a water control valve is provided on the protrusion, a water inlet valve is provided on the reaction frame base, multiple evenly distributed lifting holes are provided on the protrusion, a base hoop is provided inside the sample preparation tube base, a base platform is provided inside the sample preparation tube base, four evenly distributed handle rings are fixedly connected to the outside of the sample preparation tube base, four evenly distributed handle rings are fixedly connected to the outside of the sample cap, a steel wire rope is fixedly connected inside the lifting hole, and a lifting beam is fixedly connected to one end of the steel wire rope.

[0008] Furthermore, the protrusion is provided with multiple water guiding grooves, which are evenly distributed on the protrusion.

[0009] Furthermore, the four rigid reaction columns pass through the connecting bolt holes, and both bolt caps are in contact with the circular cover plate of the reaction frame.

[0010] Furthermore, a water-permeable air hole is provided on the reaction frame base, and the water-permeable air hole is located at the center of the reaction frame base and is connected to the water inlet valve.

[0011] Furthermore, the protrusion is provided with a water-permeable air hole, which is connected to the water-permeable air hole on the reaction frame base.

[0012] The principle of this scheme is as follows: During the saturation process, water from the high-level water tank reaches the inlet valve at the base of the reaction frame through the conduit, enters the base of the reaction frame, passes through the center of the top surface of the base of the reaction frame, and flows into the vertical permeable hole and water control valve in the cylindrical boss above the base of the reaction frame to the top surface of the cylindrical boss. The water flows through the annular and radial water guiding grooves set on the top surface of the cylindrical boss, passes through the permeable plate and enters the interior of the sample until it reaches the permeable plate and sample cap on the top surface of the sample, passes through the vent hole in the sample cap, and is discharged from the air extraction valve.

[0013] After the sample is saturated, close the water inlet valve on the reaction frame base and the water control valve on the cylindrical boss. Under negative pressure, remove the outer sample preparation bucket and sample preparation bucket base, and wrap the sample upright with several layers of plastic wrap. Insert the four hooks into the lifting holes on the bottom side of the cylindrical boss, and use a crane to lift the crossbeam and transfer it to the triaxial testing machine for testing.

[0014] The beneficial effects of this solution are as follows: This invention uses a threaded spinning rod to drive a pusher disc for precise control of the total density of layered remolded coarse-grained soil; rapid saturation and self-standing of the sample after demolding can be achieved by controlling the water inlet valve, water control valve, and air extraction valve; multiple samples can be prepared under a triaxial compression testing machine through the sample opening, wire rope, and lifting beam, facilitating the transfer of samples to the triaxial testing machine. Compared with traditional equipment, this solution can significantly reduce the saturation time of the sample and facilitates convenient transfer to the testing machine, making operation convenient.

[0015] Another objective of this scheme is to provide a triaxial test sample preparation method for coarse-grained soil with saturation and sample transfer capabilities, the specific steps of which are as follows:

[0016] (1) Install the cylindrical boss with water-permeable air holes and water control valve at the center of the reaction frame base, place the water-permeable plate on the cylindrical boss, put the bottom of the cylindrical rubber membrane on the outside of the cylindrical boss and clamp the annular water-stop clamp.

[0017] (2) The sample tube base is placed on the outside of the cylindrical boss, and its bottom is inserted into the annular groove of the reaction frame base;

[0018] (3) Place the three-lobed circular sample tubes one by one on the base platform. The bottom outer side of the sample tube is inserted into the base hoop. Ensure that the joints of the three templates of the three-lobed circular sample tube are aligned and tightened. Fix it with the outer diameter hoop bolts of the sample tube. Turn the top of the rubber film that exceeds the height of the sample tube outward to the outside of the top of the sample tube.

[0019] (4) Divide the sample into multiple parts according to the method of controlling average density. After layering a certain thickness of coarse soil sample inside the rubber membrane, fix the circular reaction cover plate to the same horizontal plane at the top of the reaction column with bolts. Pass the graduated threaded spinning rod through the central bolt hole of the circular cover plate of the reaction frame. Use the pusher disc with the threaded spinning rod attached and rotatable to press the sample. By rotating the handle on one side of the top of the screw, press the filled coarse soil to the specified thickness to control its overall density. Then, remove the pusher disc from the sample preparation bucket through the threaded spinning rod. Continue to layer the coarse soil sample, press it again, and repeat this operation until the sample reaches the design height.

[0020] (5) Remove the pusher disc with rigid threaded rod, the round cover plate of the reaction frame, and the rigid reaction column. Install the permeable plate and the air extraction valve on the top of the sample. Turn the rubber membrane that is turned outward on the outside of the sample preparation barrel to the bottom of the sample cap and clamp the annular water stop clamp.

[0021] (6) Adjust the water control valve on the cylindrical boss to close the water-permeable air hole in the cylindrical boss, open the air extraction valve on the sample cap, and connect an air pump that can maintain negative pressure to the air extraction valve. Apply a negative pressure of 30-50KPa. When there is no air leakage in the connection between the sample membrane and the connection between the cylindrical boss and the reaction frame base, the negative pressure can be maintained for 0.5-1 hours. Then remove the outer sample preparation bucket to keep the sample upright. Wrap several layers of plastic wrap tightly on the outside of the rubber membrane. Connect the water inlet valve at the reaction frame base to the high-level water tank. Open the water inlet valve at the reaction frame base and the water control valve on the cylindrical boss. Maintain a negative pressure of 30KPa to fully saturate the coarse soil sample until a uniform and continuous water flow appears in the air extraction valve. Close the water inlet valve on the reaction frame base and the water control valve on the cylindrical boss. Remove the air pump, the high-level water tank conduit, and the sample preparation bucket base.

[0022] (7) Insert the four hooks into the lifting holes on the bottom side of the cylindrical boss, and use a crane to lift the crossbeam and transfer it to the triaxial testing machine for testing.

[0023] (8) Once the preparation, saturation, and transfer of the cylindrical coarse-grained soil sample are completed, it can be used for dynamic triaxial compression testing. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a spinning-type coarse-grained soil triaxial test sample preparation device and sample preparation method with saturation and transfer sample functions according to an embodiment of the present invention;

[0025] Figure 2 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 Front view of the base

[0026] Figure 3 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 A top view of a three-lobed circular sample preparation tube;

[0027] Figure 4 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 3 A magnified view of a portion of the image;

[0028] Figure 5 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 A front view of a three-lobed circular sample preparation tube;

[0029] Figure 6 An exploded view of the reaction frame base of the spinning-type coarse-grained soil triaxial test sample preparation device and sample preparation method with saturation and sample transfer functions according to an embodiment of the present invention;

[0030] Figure 7 An exploded view of the boss of the spinning-type coarse-grained soil triaxial test sample preparation device and sample preparation method with saturation and transfer sample functions according to an embodiment of the present invention.

[0031] Figure 8 This is an axonometric view of the permeable plate of the spin-pressed coarse-grained soil triaxial test sample preparation device and sample preparation method with saturation and sample transfer functions according to an embodiment of the present invention.

[0032] Figure 9 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 A schematic diagram of the sample tube base;

[0033] Figure 10 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 A top view of the sample tube base;

[0034] Figure 11 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 Axonometric view of the sample preparation tube base;

[0035] Figure 12This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 Enlarged view of the sample cap;

[0036] Figure 13 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 Top view of the sample cap;

[0037] Figure 14 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 1 Axial view of the sample cap;

[0038] Figure 15 This is a schematic diagram of the saturation and transfer process of the spin-pressed coarse-grained soil triaxial test sample preparation device and sample preparation method with saturation and transfer sample functions according to an embodiment of the present invention;

[0039] Figure 16 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 15 A sectional view;

[0040] Figure 17 This is a schematic diagram of the transfer process of the spin-pressed coarse-grained soil triaxial test sample preparation device and sample preparation method with saturation and sample transfer functions according to an embodiment of the present invention;

[0041] Figure 18 This invention relates to a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, as described in this embodiment. Figure 17 A sectional view. Detailed Implementation

[0042] The following detailed description illustrates the specific implementation method:

[0043] The reference numerals in the accompanying drawings of the instruction manual include: 1. reaction frame base; 2. boss; 3. annular groove; 4. permeable plate; 5. rigid reaction column; 6. rubber membrane; 7. annular water-stop clamp; 8. sample tube base; 9. three-lobed circular sample tube; 10. joint; 11. clamping groove; 12. clamping bolt; 13. reaction frame circular cover plate; 14. threaded spinning rod; 15. push head disc; 16. handle; 17. bolt cap; 18. connecting bolt hole; 19. center bolt hole; 20. sample cap; 21. air extraction valve; 22. air vent; 23. water inlet valve; 24. water control valve; 25. lifting hole; 26. base hoop ring; 27. base platform; 28. handle ring; 29. ​​connecting screw hole; 30. coarse soil sample; 31. steel wire rope; 32. lifting crossbeam; 33. water guide trench; 34.

[0044] like Figure 1-10 , Figure 15-18 As shown, this embodiment provides a spinning-type coarse-grained soil triaxial test sample preparation device and method with saturation and sample transfer functions, including a reaction frame base 1 and a sample preparation cylinder base 8. A boss 2 is fixedly connected to the upper end of the reaction frame base 1. An annular groove 3 is formed on the reaction frame base 1. Four evenly distributed connecting screw holes 30 are formed on the upper part of the reaction frame base 1. A rigid reaction column 5 is threaded into the interior of each connecting screw hole 30. A rubber membrane 6 is sleeved on the outside of the boss 2. Two symmetrically distributed annular water-stopping clips 7 are sleeved on the outside of the rubber membrane 6. A three-lobed circular sample preparation cylinder 9 is fixedly connected to the outside of the sample preparation cylinder base 8. The rubber membrane 6 contacts the three-lobed circular sample preparation cylinder 9. A seam 10 is provided on the three-lobed circular sample preparation cylinder 9. Multiple evenly distributed slotted clamps 11 are fixedly connected to the three-lobed circular sample preparation cylinder 9. The inside of the slotted clamps 11 is connected to clamping bolts 12 by threads. The inside of the three-lobed circular sample preparation cylinder 9 is slidably connected to a pusher disc 15. The inside of the pusher disc 15 is fixedly and rotatably connected to a threaded spinning rod 14. The outside of the threaded spinning rod 14 is connected to a reaction frame circular cover plate 13 by threads. The reaction frame circular cover plate 13 has a central bolt hole 19 and multiple evenly distributed connecting bolt holes 18. Four rigid reaction columns 5 pass through the connecting bolt holes 18. Both bolt caps 17 are in contact with the reaction frame circular cover plate 13. The reaction frame circular cover plate 13 can be fixed by the bolt caps 17.

[0045] like Figure 1-14 As shown, each rigid reaction column 5 is connected to two symmetrically distributed bolt caps 17 by thread. The interior of the three-lobed circular sample tube 9 is provided with two symmetrically distributed permeable plates 4. The upper end of the annular water-stop clamp 7 is fitted with a sample cap 20. The interior of the sample cap 20 is fixedly connected with an air extraction valve 21. The sample cap 20 has an air vent 22. The boss 2 is provided with a water control valve 25. The reaction frame base 1 is provided with a water inlet valve 24. The boss 2 has multiple evenly distributed lifting holes 26. The steel wire rope 32 passes through the inside of the handle ring 29 on the outside of the sample tube base 8 and through the handle ring 29 on the outside of the sample cap 20. The device can be lifted by the steel wire rope 32. The boss 2 has multiple water guiding grooves 34. The multiple water guiding grooves 34 are evenly distributed on the boss 2. By setting multiple water guiding grooves 34, the water inside the reaction frame base 1 can be fully discharged.

[0046] like Figure 6-14As shown, the sample preparation cylinder base 8 has a base hoop 27 inside and a base platform 28 inside. Four evenly distributed handle rings 29 are fixedly connected to the outside of the sample preparation cylinder base 8. Four evenly distributed handle rings 29 are also fixedly connected to the outside of the sample cap 20. A steel wire rope 32 is fixedly connected inside the lifting hole 26, and one end of the steel wire rope 32 is fixedly connected to a lifting beam 33. Multiple water-permeable air holes 23 are evenly distributed on the permeable plate 4, allowing excess water to drain. A water-permeable air hole 23 is also provided on the reaction frame base 1, located at its center, and is connected to a water inlet valve. A water-permeable air hole 23 is also provided at the center of the boss 2, communicating with the water-permeable air hole on the reaction frame base. Thus, by opening the water inlet valve, water from the water tank can enter the sample preparation cylinder through the water-permeable air hole.

[0047] According to the experimental requirements, coarse-grained soil sample 31 is a cylindrical sample with a height of 450 mm and a diameter of 200 mm.

[0048] Horizontal dimensional requirements for the sample preparation device: The diameter of the sample is the same as the top diameter of the cylindrical boss placed on the reaction frame base plate, the diameter of the permeable plate, the inner diameter of the cylindrical rubber membrane, and the outer diameter of the sample cap, using a disc-shaped pusher. The outer surface of the sample is wrapped with a 3mm thick rubber membrane, the outer diameter of which matches the inner diameter of the sample preparation barrel and the inner diameter of the sample preparation barrel base platform, taking 206mm. The outer diameter of the sample preparation barrel matches the inner diameter of the sample preparation barrel base ring, and the sample preparation barrel wall thickness is 10mm, i.e., the outer diameter of the sample preparation barrel is 226mm. The bottom ring of the sample preparation barrel base component can be inserted into the annular groove of the reaction frame base, with both dimensions matching, their inner and outer diameters being 246mm and 265mm respectively. The top surface of the reaction frame base has a circular recess, the dimensions of which match the bottom surface dimensions of the cylindrical boss, and the two are sealed with a rubber ring to prevent water leakage.

[0049] Regarding the vertical dimensions of the sample preparation device: the height of the sample preparation cylinder should be slightly greater than the top position of the sample during the preparation process, and the height of the sample preparation cylinder should preferably be 550mm. The top of the rubber membrane should extend 50mm beyond the height of the sample preparation cylinder, the bottom of which should fit over the cylindrical protrusion should be 25mm long, and the height of the permeable plate should be 10mm. Therefore, the length of the rubber membrane should be 645mm.

[0050] The height of the cylindrical boss is 40mm, and the total height of the sample barrel base is 80mm. The distance from the sample barrel base platform to the bottom of the circular ring of the sample barrel base is 65mm, the height of the sample barrel base ring is 15mm, the depth of the annular groove on the top surface of the reaction frame base is 10mm, and the depth of the circular recess on the top surface is 2.5mm. That is, after installing the reaction frame base plate, cylindrical boss, and permeable plate from bottom to top, the sample barrel base is installed on the outside of the cylindrical boss and inserted into the annular groove of the reaction frame base. At this time, the height of the sample barrel base platform is consistent with the height of the permeable plate.

[0051] The following requirements apply to the design and connection of the vent / water holes: A cylindrical boss with water-permeable holes and a water control valve shall have vertical water-permeable holes at the center of its top and bottom surfaces, and the opening and closing of these holes shall be controlled by adjusting the horizontal water control valve. A water-permeable hole shall be provided between the center of the top surface of the reaction frame base and its water inlet valve. A vent hole shall be provided between the suction valve on one side of the sample cap and the center of the bottom of the sample cap, and the bottom of the sample cap shall have an upward-facing conical recess. The suction valve on the sample cap shall be connected to an external suction pump capable of maintaining a negative pressure of 30 kPa. Both the suction valve on the sample cap and the water control valve on the cylindrical boss shall be able to withstand the negative pressure generated during sample preparation. Several radial and circumferential water-guiding grooves shall be arranged on the top surface of the cylindrical boss, forming a fine mesh of permeable grooves that match the permeable holes of the permeable plate. A vent hole is provided between the air extraction valve on one side of the sample cap and the middle position of the bottom of the sample cap. The air extraction valve is connected to an air pump that can control the air pressure. The bottom of the sample cap is provided with an upward-facing conical indentation.

[0052] The following requirements apply to the direction of water flow during the saturation process of coarse-grained soil sample 31: During saturation, water flows from the high-level water tank through a conduit to the inlet valve at the base of the reaction frame, enters the base of the reaction frame, passes through the center of the top surface of the base of the reaction frame, and flows into the vertical permeable hole and control valve of the cylindrical boss above the base of the reaction frame to the top surface of the cylindrical boss. The water flows through the annular and radial water guiding grooves set on the top surface of the cylindrical boss, passes through the permeable plate and enters the interior of the sample until it reaches the permeable plate and sample cap on the top surface of the sample, passes through the vent hole in the sample cap, and is discharged from the air extraction valve.

[0053] The procedure for transferring samples that have been degassed and saturated with water is as follows: After the sample is saturated, close the water inlet valve on the reaction frame base and the water control valve on the cylindrical boss. While maintaining negative pressure, remove the outer sample preparation container and its base. Wrap the sample upright with several layers of cling film. Insert the four hooks into the lifting holes on the bottom of the cylindrical boss and use a crane to lift the crossbeam and transfer the sample to the triaxial testing machine for testing. During transport, keep the sample vertical and avoid collisions.

[0054] The sample preparation process of a spinning-type triaxial test sample preparation device for coarse-grained soil with saturation and sample transfer functions is as follows:

[0055] (1) Install the cylindrical boss 2 with water-permeable air hole 23 and water control valve 25 at the center of the reaction frame base 1, place the water-permeable plate 4 on the cylindrical boss 2, put the bottom of the cylindrical rubber membrane 6 on the outside of the cylindrical boss 2 and clamp the annular water-stopping clamp 7.

[0056] (2) The sample tube base 8 is placed on the outside of the cylindrical boss 2, and its bottom is inserted into the annular groove 3 of the reaction frame base 1;

[0057] (3) Place the three-lobed circular sample tubes 9 one by one on the base platform 28. The bottom outer side of the sample tube is inserted into the base hoop 27. Ensure that the joints 10 of the three templates of the three-lobed circular sample tube 9 are aligned and tightened. Fix them with the outer diameter hoop bolts 12 of the sample tube. Turn the top of the rubber membrane 6, which exceeds the height of the sample tube, outward to the outside of the top of the sample tube. In this way, the rubber membrane can play a good auxiliary fixing role.

[0058] (4) Divide the sample into multiple parts according to the method of controlling average density. After layering a certain thickness of coarse soil sample 31 inside the rubber membrane 6, fix the circular reaction cover plate to the same horizontal plane at the top of the reaction column with bolts. Then, pass the graduated threaded spinning rod 14 through the central bolt hole 19 of the circular cover plate 13 of the reaction frame. Use the pusher disc 15, which is connected to the threaded spinning rod 14 and can be rotated, to press the sample. By rotating the handle 16 on one side of the top of the screw, the filled coarse soil is spun to the specified thickness to control its overall density. Then, the pusher disc 15 is removed from the sample preparation bucket by the threaded spinning rod 14. Continue to layer the coarse soil sample 31, spun again, and repeat this operation until the sample reaches the designed height.

[0059] (5) Remove the pusher disc 15, reaction frame circular cover plate 13, and rigid reaction column 5 connected with rigid threaded rod. Install the permeable plate 4, air extraction valve 21, and sample cap 20 on the top of the sample. Turn the rubber membrane 6, which is turned outward on the outside of the sample preparation barrel, to the bottom of the sample cap 20 and clamp the annular water-stop clamp 7. In this way, the rubber membrane ensures the sealing of the equipment.

[0060] (6) Adjust the water control valve 25 on the cylindrical boss 2 to close the water permeable air hole 23 in the cylindrical boss 2, open the air extraction valve 21 on the sample cap 20, and connect an air extraction pump that can maintain negative pressure to the air extraction valve 21. Apply a negative pressure of 30-50KPa. When there is no air leakage in the connection between the sample membrane and the connection between the cylindrical boss 2 and the reaction frame base 1, the negative pressure of 30KPa can be maintained for 0.5-1 hours. Then remove the outer sample preparation bucket to keep the sample upright and wrap several layers of plastic wrap tightly around the outside of the rubber membrane 6. The water inlet valve 24 at the reaction frame base 1 is connected to an external high-level water tank. Open the water inlet valve 24 at the reaction frame base 1 and the water control valve 25 on the cylindrical boss 2. Maintain a negative pressure of 30 kPa to fully saturate the coarse soil sample 31 until a uniform and continuous water flow appears in the air extraction valve 21. Close the water inlet valve 24 on the reaction frame base 1 and the water control valve 25 on the cylindrical boss 2. Remove the air extraction pump, the high-level water tank conduit, and the sample preparation bucket base.

[0061] (7) Insert the four hooks into the lifting holes 26 on the bottom side of the cylindrical boss 2, and use a crane to lift the crossbeam and transfer it to the triaxial testing machine for testing.

[0062] (8) Once the preparation, saturation, and transfer of the cylindrical coarse-grained soil sample are completed, it can be used for dynamic triaxial compression testing.

[0063] It should be noted in advance that, in this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0064] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A triaxial sample preparation device for coarse-grained soil with saturation and transfer sample functions, comprising a reaction frame base, a sample cap, and a sample preparation cylinder base, characterized in that: The upper end of the reaction frame base is equipped with a boss, and an annular groove is formed on the reaction frame base. Multiple evenly distributed connecting screw holes are formed on the reaction frame base, and a rigid reaction column is threaded into each connecting screw hole. A rubber membrane is sleeved on the outside of the boss, and two symmetrically distributed annular water-stop clamps are sleeved on the outside of the rubber membrane. A sample preparation cylinder is fixedly connected to the outside of the sample preparation cylinder base, and the rubber membrane contacts the sample preparation cylinder. A seam is provided on the sample preparation cylinder, and multiple evenly distributed clamping grooves are fixedly connected to the sample preparation cylinder. Clamping bolts are threaded into the clamping grooves. The sample preparation cylinder is a three-lobed circular sample preparation cylinder. A pusher disc is slidably connected inside the three-lobed circular sample preparation cylinder, and a threaded spinning rod is rotatably connected inside the pusher disc. A circular cover plate of the reaction frame is threaded into the outside of the threaded spinning rod, and a central bolt hole is formed on the circular cover plate of the reaction frame. The reaction frame circular cover plate has multiple evenly distributed connecting bolt holes. Each rigid reaction column has two symmetrically distributed bolt caps connected by threads. The three-lobed circular sample preparation cylinder has two symmetrically distributed permeable plates inside. The upper end of the annular water-stop clamp is fitted with a sample cap, which has a vent hole. One side of the sample cap is fixedly connected to an air extraction valve communicating with the vent hole. A water control valve is provided on the protrusion. A water inlet valve is provided on the reaction frame base. Multiple evenly distributed lifting holes are provided on the protrusion. A base hoop is provided inside the sample preparation cylinder base. A base platform is provided inside the sample preparation cylinder base. Four evenly distributed handle rings are fixedly connected to the outside of the sample preparation cylinder base. Four evenly distributed handle rings are fixedly connected to the outside of the sample cap. A steel wire rope is fixedly connected inside the lifting hole. One end of the steel wire rope is fixedly connected to a lifting beam.

2. The coarse-grained soil triaxial sample preparation device with saturation and transfer sample functions according to claim 1, characterized in that: The protrusion is provided with multiple water guiding grooves, which are evenly distributed on the protrusion.

3. The coarse-grained soil triaxial sample preparation device with saturation and transfer sample functions according to claim 1, characterized in that: The reaction frame base is provided with a water-permeable air hole, which is located at the center of the reaction frame base and is connected to the water inlet valve.

4. The coarse-grained soil triaxial sample preparation device with saturation and transfer sample functions according to claim 1, characterized in that: The protrusion is provided with a water-permeable air hole, which is connected to the water-permeable air hole on the reaction frame base.

5. The method for preparing coarse-grained soil triaxial samples using a coarse-grained soil triaxial sampler with saturation and transfer sample functions according to any one of claims 1-4, characterized in that: The specific steps are as follows: (1) Install the cylindrical boss with water-permeable air holes and water control valve at the center of the reaction frame base, place the water-permeable plate on the cylindrical boss, put the bottom of the cylindrical rubber membrane on the outside of the cylindrical boss and clamp the annular water-stop clamp. (2) The sample tube base is placed on the outside of the cylindrical boss, and its bottom is inserted into the annular groove of the reaction frame base; (3) Place the three-lobed circular sample tubes one by one on the base platform. Insert the bottom outer side of the sample tube into the base hoop ring and ensure that the joints of the three templates of the three-lobed circular sample tube are aligned and tightened. Fix it with the outer diameter hoop bolts of the sample tube and turn the top of the rubber film that exceeds the height of the sample tube outward to the outside of the top of the sample tube. (4) Divide the sample into multiple parts according to the method of controlling average density. After layering a certain thickness of coarse soil sample inside the rubber membrane, fix the circular reaction cover plate to the same horizontal plane at the top of the reaction column with bolts. Pass the graduated threaded spinning rod through the central bolt hole of the circular cover plate of the reaction frame. Use the pusher disc with the threaded spinning rod attached and rotatable to press the sample. By rotating the handle on one side of the top of the screw, the filled coarse soil is spun to the specified thickness to control its overall density. Then, the pusher disc is removed from the sample preparation cylinder by the threaded spinning rod. Continue to layer the coarse soil sample, spun again, and repeat this operation until the sample reaches the design height. (5) Remove the pusher disc with rigid threaded rod, the round cover plate of the reaction frame, and the rigid reaction column. Install the permeable plate and the sample cap of the air extraction valve on the top of the sample. Turn the rubber membrane that is turned outward on the outside of the sample preparation tube to the bottom of the sample cap and clamp the annular water stop clamp. (6) Adjust the water control valve on the cylindrical boss to close the water-permeable air hole in the cylindrical boss, open the air extraction valve on the sample cap, and connect an air pump that can maintain negative pressure to the air extraction valve. Apply a negative pressure of 30-50KPa. When there is no air leakage in the connection between the sample membrane and the connection between the cylindrical boss and the reaction frame base, the negative pressure can be maintained for 0.5-1 hours. Then remove the outer sample preparation tube to keep the sample upright. Wrap several layers of plastic wrap tightly on the outside of the rubber membrane. Connect the water inlet valve at the reaction frame base to the high-level water tank. Open the water inlet valve at the reaction frame base and the water control valve on the cylindrical boss. Maintain a negative pressure of 30KPa to fully saturate the coarse soil sample until a uniform and continuous water flow appears in the air extraction valve. Close the water inlet valve on the reaction frame base and the water control valve on the cylindrical boss. Remove the air pump, the high-level water tank conduit, and the sample preparation tube base. (7) Insert the four hooks into the lifting holes on the bottom side of the cylindrical boss, and use a crane to lift the crossbeam and transfer it to the triaxial testing machine for testing. (8) Once the preparation, saturation, and transfer of the cylindrical coarse-grained soil sample are completed, it can be used for dynamic triaxial compression testing.

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