A soft soil pre-consolidation sample preparation device

Abstract

The present invention discloses a soft soil pre-consolidation sampling device, comprising: a reaction frame, a sample tube and a force-applying frame; a connecting seat is provided on the bottom plate of the reaction frame, and the connecting seat is connected to a drainage valve; the bottom end of the sample tube is detachably connected to the connecting seat, and the top and bottom ends of the sample tube can both be detachably connected to the connecting seat, and the sample tube can repeatedly switch the installation direction during the sampling process; the force-applying frame is installed on the upper part of the reaction frame, and the bottom of the force-applying frame has a pressure head, which is slidably connected to the inner wall of the sample tube. The soft soil pre-consolidation sampling device provided by the present invention utilizes a sample tube that can be disassembled on the connecting seat, and can repeatedly switch the installation direction during the sampling process, thereby changing the load application direction, eliminating the influence of friction on the side wall of the sample tube, making the moisture content inside the soil sample uniformly distributed, and ensuring the quality of the sample.

Description

Technical Field

[0001] The invention relates to the technical field of indoor geotechnical testing of geotechnical engineering, and more particularly to a soft soil pre-consolidation sample preparation device. Background Art

[0002] With the advancement of urbanization in my country, land resources are becoming increasingly scarce, and land reclamation has gradually become a major means of urban expansion. Dredged silt is widely used in land reclamation projects in my country's southeastern coastal areas. Due to the unique sedimentation process, coastal dredged soil often has an extremely high water content (over 1.5 times the soil liquid limit), resulting in extremely high compressibility and very low shear strength.

[0003] Triaxial compression testing is one of the important means of evaluating the engineering properties of soil. Sample quality is a key factor affecting the accuracy of triaxial compression test results. However, existing triaxial sampling methods for soft soils cannot meet the sampling requirements of ultra-soft soils with extremely high water content:

[0004] First, triaxial compression specimens are usually cylindrical (e.g., 39.1 mm in diameter and 80 mm in height). During the pre-consolidation process, friction between the soil sample and the inner wall of the specimen cylinder cannot be ignored, resulting in uneven distribution of the soil consolidation degree and moisture content along the height direction, which seriously affects the triaxial test results.

[0005] In addition, since soft soil cannot support the weight of the permeable stone and the top cover, the existing triaxial sampling device is difficult to ensure that the permeable stone and the sample top cover are level during the primary loading stage, resulting in friction between them and the inner wall of the sample tube and soil squeezing, making the applied load inaccurate.

[0006] Therefore, how to make up for the above-mentioned defects and develop a new soft soil triaxial preconsolidation sampling device is a problem that technical personnel in this field urgently need to solve. Summary of the Invention

[0007] In view of this, the present invention provides a soft soil pre-consolidation sampling device, aiming to solve the above technical problems.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A soft soil pre-consolidation sample preparation device, comprising:

[0010] A reaction frame, wherein a connecting seat is provided on the bottom plate of the reaction frame, and the connecting seat is connected to a drainage valve;

[0011] A sample tube, wherein the bottom end of the sample tube is detachably connected to the connecting seat, and both the top and bottom ends of the sample tube are detachably connected to the connecting seat, and the sample tube can repeatedly switch the installation direction during the sample preparation process;

[0012] A force-applying frame is installed on the upper part of the reaction frame. The bottom of the force-applying frame is provided with a pressure head, and the pressure head is slidably connected to the inner wall of the sample tube.

[0013] Through the above technical solution, the soft soil pre-consolidation sampling device provided by the present invention can be disassembled on the connecting seat by using the sample tube, and the installation direction can be repeatedly switched during the sampling process, which can eliminate the influence of friction on the side wall of the sample tube, so that the internal force and moisture content of the soil sample are evenly distributed, thereby ensuring the quality of the sample.

[0014] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, the top of the connecting seat has a connecting groove, the inner sidewall of the connecting groove has an internal thread, and both ends of the sample tube have external threads. The threaded connection method is convenient for disassembly and connection and can ensure stability.

[0015] Preferably, in the aforementioned soft soil pre-consolidation sampling device, a drainage channel is defined within the connection base, one end of the drainage channel communicating with the connection groove, and the other end of the drainage channel extending through the side wall of the connection base and connected to the drainage valve; a permeable stone is embedded in the bottom surface of the connection groove. The design of the drainage channel enables effective drainage of moisture released from the soil sample during sampling, and can be controlled to open and close.

[0016] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, the force frame includes a main rod, a gravity assembly and a loading connecting rod. The main rod is arranged vertically and is slidably connected to the crossbeam in the middle of the reaction frame; the gravity assembly is connected to the top of the main rod and the top of the reaction frame; the top of the loading connecting rod is fixedly connected to the bottom of the main rod, and the bottom of the loading connecting rod is detachably connected to the pressure head. The main rod of the force frame can slide up and down, thereby driving the loading connecting rod and the pressure head to move up and down. When it moves downward, force sampling can be achieved, and when it moves upward, the force can be released through manual control.

[0017] Preferably, in the above-mentioned soft soil preconsolidation sampling device, the gravity assembly includes a fixed pulley, a first loading plate, a rope, and a second loading plate; there are two fixed pulleys, both mounted on the bottom surface of the top plate of the reaction frame; the first loading plate is fixed to the top of the main rod, and a weight limiting rod is fixed to the top surface of the first loading plate; one end of the rope is fixed to the top of the weight limiting rod and passes over the top of the two fixed pulleys in sequence; the second loading plate is fixedly connected to the end of the rope away from the weight limiting rod. Through the cooperation of the first loading plate, the second loading plate, and the fixed pulley, different pressures can be adjusted during the process of removing and placing weights.

[0018] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, the top surface of the pressure head is magnetically connected to the loading connecting rod, which makes the connection simple and the structure stable.

[0019] Preferably, in the soft soil preconsolidation sampling device, the top surface of the pressure head is provided with a magnetic hemispherical groove, and the bottom end of the loading connecting rod has a magnetic hemispherical groove. The structural coordination of the magnetic hemispherical groove and the magnetic hemispherical groove can further improve the stability of the connection between the loading connecting rod and the pressure head.

[0020] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, the pressure head is a water-permeable structure, capable of cooperating with top drainage.

[0021] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, the side wall of the sample tube has a drainage hole, which can cooperate with the side wall for drainage.

[0022] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, the number of the connecting seat, the sample tube and the pressure head is multiple, so that samples of the same nature can be prepared at the same time according to different requirements.

[0023] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, a dial indicator can be installed at the loading connecting rod to monitor the soil deformation during the sampling process, thereby drawing a consolidation curve and determining the optimal loading time.

[0024] It can be seen from the above technical solutions that, compared with the prior art, the present invention provides a method having the following beneficial effects:

[0025] 1. The present invention adopts a magnetic permeable pressure head, which can be connected to the loading connecting rod to balance the weight of the pressure head and maintain it in a horizontal state, making up for the deficiency that the pressure head deflects due to the soft soil, making the direction of applied stress tilted.

[0026] 2. The sample tube of the present invention can be turned upside down and then connected to the connecting seat, thereby eliminating the influence of side wall friction, making the moisture content inside the soil sample evenly distributed, and greatly improving the sample quality.

[0027] 3. The present invention can prepare multiple parallel samples at the same time, which can be used to carry out the same series of compression tests, thereby improving sample preparation efficiency and ensuring the reliability of the test results.

[0028] 4. The present invention applies the primary load by gradually removing the weights on the second loading plate. The initial load can be adjusted arbitrarily according to the moisture content of the soil sample to avoid soil squeezing.

[0029] 5. The side wall of the sample tube of the present invention is provided with drainage holes, which can achieve uniform drainage around the soil and greatly improve the consolidation efficiency.

[0030] 6. The present invention can replace the sample tube according to the test requirements to carry out consolidation sampling of ultra-soft soil samples of different sizes.

[0031] 7. The present invention adopts a frame structure, which is small in size, light in weight, and easy to use in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0033] Figure 1 The accompanying drawing is a front view of the soft soil pre-consolidation sample preparation device provided by the present invention;

[0034] Figure 2 The accompanying drawing is a top view of the soft soil pre-consolidation sample preparation device provided by the present invention;

[0035] Figure 3 The accompanying drawing is a cross-sectional view of the connecting seat provided by the present invention;

[0036] Figure 4 The accompanying drawing is an exploded view of the loading connecting rod and the pressure head provided by the present invention.

[0037] in:

[0038] 1-Reaction frame;

[0039] 11- bottom plate; 12- cross beam; 13- top plate;

[0040] 2- sample tube;

[0041] 3-Force rack;

[0042] 31-pressure head; 311-magnetic hemisphere slot; 32-main rod; 33-gravity assembly; 331-fixed pulley; 332-first loading plate; 333-rope; 334-second loading plate; 335-weight limiting rod; 34-loading connecting rod; 341-magnetic hemisphere;

[0043] 4-Connection seat;

[0044] 41-connecting groove; 42-drainage channel; 43-permeable stone;

[0045] 5-Drain valve;

[0046] 6-Weights. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] See attached Figure 1 The embodiment of the present invention discloses a soft soil pre-consolidation sample preparation device, comprising:

[0049] A reaction frame 1, a connecting seat 4 is provided on the bottom plate 11 of the reaction frame 1, and a drain valve 5 is connected to the connecting seat 4;

[0050] The sample tube 2 has a bottom end detachably connected to the connecting base 4, and both the top and bottom ends of the sample tube 2 can be detachably connected to the connecting base 4. The sample tube 2 can repeatedly switch its installation direction during the sample preparation process.

[0051] The force-applying frame 3 is installed on the upper part of the reaction frame 1 . The bottom of the force-applying frame 3 is provided with a pressure head 31 . The pressure head 31 is slidably connected to the inner wall of the sample tube 2 .

[0052] See attached Figure 3 The top of the connecting seat 4 has a connecting groove 41, the inner side wall of the connecting groove 41 has an internal thread, and both ends of the sample tube 2 have external threads.

[0053] In order to further optimize the above technical solution, a drainage channel 42 is opened inside the connecting seat 4, one end of the drainage channel 42 is connected to the connecting groove 41, and the other end of the drainage channel 42 passes through the side wall of the connecting seat 4 and is connected to the drainage valve 5; a permeable stone 43 is embedded in the bottom surface of the connecting groove 41.

[0054] In order to further optimize the above technical solution, the force frame 3 includes a main rod 32, a gravity assembly 33 and a loading connecting rod 34; the main rod 32 is arranged vertically and is slidingly connected to the crossbeam 12 in the middle of the reaction frame 1; the gravity assembly 33 is connected to the top of the main rod 32 and the top of the reaction frame 1; the top of the loading connecting rod 34 is fixedly connected to the bottom end of the main rod 32, and the bottom end of the loading connecting rod 34 is detachably connected to the pressure head 31.

[0055] In order to further optimize the above technical solution, the gravity assembly 33 includes a fixed pulley 331, a first loading plate 332, a rope 333 and a second loading plate 334; there are two fixed pulleys 331, and both are installed on the bottom surface of the top plate of the reaction frame 1; the first loading plate 332 is fixed to the top of the main rod 32, and a weight limiting rod 335 is fixed to the top surface of the first loading plate 332; one end of the rope 333 is fixed to the top of the weight limiting rod 335, and passes around the upper part of the two fixed pulleys 331 in turn; the second loading plate 334 is fixedly connected to the end of the rope 333 away from the weight limiting rod 335.

[0056] In order to further optimize the above technical solution, the top surface of the pressure head 31 is magnetically connected to the loading connecting rod 34.

[0057] See attached Figure 4 The top surface of the pressure head 31 is provided with a magnetic hemisphere groove 311 , and the bottom end of the loading connecting rod 34 is provided with a magnetic hemisphere 341 .

[0058] In order to further optimize the above technical solution, the pressure head 31 is a water-permeable structure.

[0059] In order to further optimize the above technical solution, the side wall of the sample tube 2 has a drainage hole.

[0060] In this embodiment, the number of connecting bases, sample cylinders 2, and pressure heads 31 is set to three, arranged in an equilateral triangle. This is primarily used for triaxial compression testing, in which the uniformity of the sample has a significant impact on the test structure. Using the structure of this embodiment, the loading system is designed with a triple force transmission rod, which can simultaneously prepare three parallel samples for conducting the same series of triaxial tests, ensuring the reliability of the test results.

[0061] Specifically, in this embodiment, the bottom end of the main rod 32 is connected to the loading connecting rod 34 through a conversion part. The conversion part is a Y-shaped frame. The bottom end of the main rod 32 is fixed to the center point of the Y-shaped frame. The loading connecting rod 34 is fixedly connected to the end of the Y-shaped frame. The three support rods of the Y-shaped frame are equal in length, and the angles of adjacent support rods are all 120°, so that the positions of the three loading connecting rods 34 meet the corresponding arrangement of the equilateral triangle of the sample tube 2.

[0062] The specific operation steps of this embodiment include:

[0063] Loading the sample: Place three sample tubes 2 on the connecting seat 4 of the reaction frame 1, tighten them by screwing, and close the drain valve 5; lay filter paper on the wall and bottom of the sample tube 2, then pour the mud to be consolidated into the sample tube 2, and lay filter paper on the top of the mud.

[0064] To conduct the test, the drain valve 5 was opened, all weights 6 were removed, and weights 6 of appropriate mass were placed on the second loading plate 334 to balance the gravity of the gravity assembly 33. When gravity reached equilibrium, pressure was applied by gradually unloading the weights 6 on the second loading plate 334 to apply a low consolidation stress. Once all weights 6 on the second loading plate 334 were removed, weights 6 were then placed on the first loading plate 332 to increase the consolidation stress. After consolidation at each load level was completed, the sample cylinder 2 was inverted and consolidation was repeated under the same stress. After sample preparation was complete, the sample cylinder 2 was removed, and the consolidated soil sample was removed using a sample pusher.

[0065] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0066] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A soft soil pre-consolidation sample preparation device, characterized in that: include: A reaction frame (1), wherein a connecting seat (4) is provided on a bottom plate (11) of the reaction frame (1), and the connecting seat (4) is connected to a drainage valve (5); A sample tube (2), wherein the top and bottom ends of the sample tube (2) are both detachably connected to the connecting seat (4), and the sample tube (2) can repeatedly switch the installation direction during the sample preparation process; A force-applying frame (3), the force-applying frame (3) being mounted on the upper portion of the reaction frame (1), the bottom of the force-applying frame (3) being provided with a pressure head (31), the pressure head (31) being slidably connected to the inner wall of the sample tube (2); The force-applying frame (3) comprises a main rod (32), a gravity assembly (33) and a loading connecting rod (34); the main rod (32) is arranged vertically and is slidably connected to the crossbeam (12) in the middle of the reaction frame (1); the gravity assembly (33) is connected to the top end of the main rod (32) and the top end of the reaction frame (1); the top end of the loading connecting rod (34) is fixedly connected to the bottom end of the main rod (32), and the bottom end of the loading connecting rod (34) is detachably connected to the pressure head (31); The gravity assembly (33) includes a fixed pulley (331), a first loading plate (332), a rope (333) and a second loading plate (334); there are two fixed pulleys (331), and both are mounted on the bottom surface of the top plate of the reaction frame (1); the first loading plate (332) is fixed to the top of the main rod (32), and a weight limiting rod (335) is fixed to the top surface of the first loading plate (332); one end of the rope (333) is fixed to the top of the weight limiting rod (335) and passes through the upper parts of the two fixed pulleys (331) in sequence; the second loading plate (334) is fixedly connected to the end of the rope (333) away from the weight limiting rod (335); The top surface of the pressure head (31) is magnetically connected to the loading connecting rod (34); The top surface of the pressure head (31) is provided with a magnetic hemisphere groove (311), and the bottom end of the loading connecting rod (34) is provided with a magnetic hemisphere (341); The pressure head (31) is a water-permeable structure.

2. A soft soil pre-consolidation sample preparation device according to claim 1, characterized in that: The top of the connecting seat (4) is provided with a connecting groove (41), the inner side wall of the connecting groove (41) is provided with an internal thread, and both ends of the sample tube (2) are provided with external threads.

3. A soft soil pre-consolidation sample preparation device according to claim 2, characterized in that: A drainage channel (42) is provided inside the connection seat (4), one end of the drainage channel (42) is communicated with the connection groove (41), and the other end of the drainage channel (42) passes through the side wall of the connection seat (4) and is connected to the drainage valve (5); a permeable stone (43) is embedded in the bottom surface of the connection groove (41).

4. The soft soil pre-consolidation sample preparation device according to claim 1, characterized in that: The side wall of the sample cylinder (2) is provided with a drainage hole.

5. The soft soil pre-consolidation sample preparation device according to claim 1, characterized in that: The connecting seat, the sample cylinder (2) and the pressure head (31) are provided in multiple sets.

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