Soft soil pre-consolidation sample preparation device

Abstract

The invention discloses a soft soil pre-consolidation sample preparation device which comprises a reaction frame, a sample cylinder and a force application frame, a connecting seat is arranged on a bottom plate of the counter-force frame and is connected with a drainage valve; the bottom end of the sample cylinder is detachably connected with the connecting seat, the top end and the bottom end of the sample cylinder can be detachably connected with the connecting seat, and the installation direction of the sample cylinder can be repeatedly switched in the sample preparation process; a pressure head is arranged at the bottom of the force application frame and is in sliding connection with the inner wall of the sample cylinder. According to the soft soil pre-consolidation sample preparation device provided by the invention, the sample cylinder can be detached from the connecting seat, and the mounting direction can be repeatedly switched in the sample preparation process, so that the load applying direction is changed, the friction influence of the side wall of the sample cylinder is eliminated, the moisture content in a soil sample is uniformly distributed, and the sample preparation quality is ensured.

Description

Technical Field

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

[0002] With the development of urbanization in my country, land resources are becoming increasingly scarce, and land reclamation has gradually become the main way of urban expansion. Dredged silt is widely used in land reclamation projects in the southeastern coastal areas of my country. Affected by the special sedimentation process, coastal dredged soil usually has an extremely high water content (1.5 times the liquid limit of the soil), resulting in extremely high compressibility and extremely low shear strength.

[0003] Triaxial compression test is one of the important means to evaluate the engineering properties of soil, and the sample quality is a key factor affecting the accuracy of triaxial compression test results. However, the existing triaxial sample preparation method for soft soil cannot meet the sample preparation requirements of ultra-soft soil samples 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). The friction between the soil sample and the inner wall of the sample tube during the pre-consolidation sample preparation process cannot be ignored, resulting in uneven distribution of the consolidation degree and moisture content of the soil sample along the height direction, which seriously affects the triaxial test results.

[0005] In addition, since the 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 type of soft soil triaxial preconsolidation sampling device is a problem that technical personnel in this field need to solve urgently. Summary of the invention

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

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

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

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

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

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

[0013] Through the above technical scheme, 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 the friction of 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 preconsolidation sample preparation device, the top of the connection seat has a connection groove, the inner side wall of the connection 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 above-mentioned soft soil pre-consolidation sampling device, a drainage channel is provided inside the connection seat, one end of the drainage channel is connected to the connection groove, and the other end of the drainage channel passes through the side wall of the connection seat and is connected to the drainage valve; a permeable stone is embedded in the bottom surface of the connection groove. The design of the drainage channel can effectively drain the water discharged from the soil sample during the sampling process, and can be opened and closed.

[0016] Preferably, in the above-mentioned soft soil preconsolidation 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, and force sampling can be achieved when going down, and the force can be released through manual control when going up.

[0017] Preferably, in the above-mentioned soft soil preconsolidation sample preparation device, the gravity assembly includes a fixed pulley, a first loading plate, a rope and a second loading plate; the number of the fixed pulleys is two, and both are installed 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 through the upper part of the two fixed pulleys in turn; 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 in the process of removing and placing weights.

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

[0019] Preferably, in the above-mentioned soft soil preconsolidation sample preparation 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 sample preparation device, the pressure head is a water-permeable structure, which can cooperate with top drainage.

[0021] Preferably, in the above-mentioned soft soil pre-consolidation sample preparation 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 sample preparation device, the number of the connecting seat, the sample tube and the pressure head are multiple sets. According to different requirements, samples of the same nature can be prepared at the same time.

[0023] Preferably, in the above-mentioned soft soil pre-consolidation sampling device, a micrometer can be installed at the loading connecting rod to monitor the soil deformation during the sampling process, so as to draw a consolidation curve and determine the optimal loading time.

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

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

[0026] 2. The sample tube of the present invention can be inverted 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 test results.

[0028] 4. The present invention applies the primary load by gradually removing the weights on the second loading plate, and 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 drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying 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 socket 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 hemispherical groove; 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 hemispherical;

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

[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 connection seat 4 is provided on the bottom plate 11 of the reaction frame 1, and a drainage valve 5 is connected to the connection seat 4;

[0050] The sample tube 2, the bottom end of the sample tube 2 is detachably connected to the connecting seat 4, and the top and bottom ends of the sample tube 2 can be detachably connected to the connecting seat 4, and the sample tube 2 can repeatedly switch the 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 slidably 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 it passes around the upper part of the two fixed pulleys 331 in turn; the second loading plate 334 is fixedly connected to one 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 hemispherical groove 311 , and the bottom end of the loading connecting rod 34 is provided with a magnetic hemispherical groove 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 the connecting seat, the sample tube 2 and the pressure head 31 are all set to 3 sets, and they are arranged in an equilateral triangle, which is mainly used for triaxial compression test. In this test, the uniformity of the sample has a great influence on the test structure. With the structure of this embodiment, the loading system is designed as a triple force transmission rod, and three parallel samples can be prepared at the same time. Three parallel samples can be prepared at the same time for carrying out the same series of triaxial tests to ensure 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 member, and the conversion member is a Y-shaped frame. The bottom end of the main rod 32 is fixed to the center point of the Y-shaped frame, and 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 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 samples: Place three sample tubes 2 on the connecting seat 4 of the reaction frame 1, tighten them by threads, 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] Test conduct: open the drain valve 5, empty all the weights 6, place the corresponding weights 6 on the second loading plate 334 to balance the gravity of the gravity assembly 33, and when the gravity reaches equilibrium, start to apply pressure by gradually unloading the weights 6 on the second loading plate 334 to apply a lower consolidation stress. When all the weights 6 on the second loading plate 334 are unloaded, then place weights 6 on the first loading plate 332 to increase the consolidation stress; after each level of load consolidation is completed, turn the sample tube 2 upside down and perform consolidation under the same stress again; after sample preparation is completed, remove the sample tube 2 and use the sample pusher to take out the consolidated soil sample.

[0065] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0066] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 will not be limited to the embodiments shown herein, but rather 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 connection seat (4) is provided on a bottom plate (11) of the reaction frame (1), and the connection seat (4) is connected to a drainage valve (5); A sample tube (2), wherein the bottom end of the sample tube (2) is detachably connected to the connection seat (4), and both the top end and the bottom end of the sample tube (2) are detachably connected to the connection seat (4), and the sample tube (2) is capable of repeatedly switching the installation direction during the sample preparation process; A force applying frame (3) is installed on the upper part of the reaction frame (1), and a pressure head (31) is provided at the bottom of the force applying frame (3), and the pressure head (31) is slidably connected to the inner wall of the sample tube (2).

2. A soft soil pre-consolidation sample preparation device according to claim 1, characterized in that: The top of the connection seat (4) is provided with a connection groove (41), the inner side wall of the connection 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); 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. A soft soil pre-consolidation sample preparation device according to claim 1, characterized in that: 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 a 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).

5. A soft soil pre-consolidation sample preparation device according to claim 4, characterized in that: The gravity assembly (33) comprises a fixed pulley (331), a first loading plate (332), a rope (333) and a second loading plate (334); there are two fixed pulleys (331), both of which 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 is passed around the upper parts of the two fixed pulleys (331) in sequence; the second loading plate (334) is fixedly connected to one end of the rope (333) away from the weight limiting rod (335).

6. A soft soil pre-consolidation sample preparation device according to claim 4, characterized in that: The top surface of the pressure head (31) is magnetically connected to the loading connecting rod (34).

7. A soft soil pre-consolidation sample preparation device according to claim 6, characterized in that: The top surface of the pressure head (31) is provided with a magnetic hemispherical groove (311), and the bottom end of the loading connecting rod (34) is provided with a magnetic hemispherical groove (341).

8. The soft soil pre-consolidation sample preparation device according to claim 6, characterized in that: The pressure head (31) is a water-permeable structure.

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

10. 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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