Constant head permeameter suitable for gravel soil
By designing a water head permeator suitable for gravel soil with a large capacity permeability cylinder and a separate base, the problem of difficulty in testing large-gravel soil in existing equipment is solved, convenient disassembly and assembly and cleaning are achieved, and the accuracy and efficiency of testing are improved.
Patent Information
- Application Number
- CN202422146628.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-03
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-09-03
AI Technical Summary
Existing common water head permeators are difficult to test the permeability coefficient of gravel soil of large particle sizes, and there are difficulties in dismantling and cleaning.
A common water head permeator suitable for gravel soil was designed, which increased the size of the permeability cylinder and adopted a separate design of the permeability cylinder and the base for easy disassembly and assembly and cleaning. The setting of the coarse sand transition layer was cancelled, and a metal orifice plate was used instead, and the support function of the metal orifice plate was provided through the support frame, simplifying the sample removal process.
The effective permeability coefficient test of gravel soil below the maximum particle size of 60mm is achieved, which simplifies the disassembly and assembly and cleaning process of the equipment, and avoids the blockage problem at the corners of the pressure measuring hole.
Smart Images
Figure CN222994275U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of geotechnical test instruments, and particularly relates to a constant head permeameter applicable to gravelly soil. Background Art
[0002] The permeability coefficient of soil is an important index reflecting the permeability ability of soil, and is an important parameter for seepage analysis, grouting design, subgrade quality evaluation and other work. The constant head permeability test is an important method for measuring the permeability coefficient of cohesionless soil. However, the conventional permeameter is limited by the diameter of the sample cylinder and is difficult to be used for testing the permeability coefficient of gravelly soil with large particle size. In addition, it is difficult to disassemble and clean the sample after the permeameter test. Therefore, it is necessary to improve the existing constant head permeameter.
[0003] The conventional type 70 permeameter is limited by the diameter of the sample cylinder and is applicable to sandy soil and the situation containing a small amount of gravel, and is difficult to be used for testing the permeability coefficient of gravelly soil with larger particle size. It is difficult to disassemble and clean the sample after the permeameter test, and the pressure measuring holes are prone to blockage at the corners. Summary of the Utility Model
[0004] The technical problem to be solved by the utility model is to provide a constant head permeameter applicable to gravelly soil in view of the above-mentioned deficiencies of the prior art. The constant head permeameter increases the size of the permeation cylinder, can be used to test the permeability coefficient of sandy soil with a maximum particle size of less than 60 mm, and the permeation cylinder and the base are designed in a separated manner, which is convenient for disassembly, installation and cleaning.
[0005] To solve the above technical problem, the technical scheme adopted by the utility model is: a constant head permeameter applicable to gravelly soil, which is characterized by comprising a permeation cylinder, a support frame and a base. The inner diameter of the permeation cylinder is 600 mm, the outer diameter is 640 mm, and the height is 900 mm. The base is in a cylindrical shape, the diameter of the base is 680 mm, a groove is arranged at the top end of the base, the groove is a circular groove, the diameter of the circular groove is 640 mm, the bottom end of the permeation cylinder is movably installed in the groove, the support frame is movably installed in the permeation cylinder, and two metal orifice plates are arranged at the top end of the support frame.
[0006] In the conventional permeameter, a coarse sand transition layer is laid on the metal orifice plate to prevent the loss of fine particles. Since the test object of this device is gravelly soil with large particle size, the permeability coefficient of the coarse sand transition layer may be smaller than that of the test object, resulting in a smaller measured permeation water volume and thus a smaller final result. And laying a more permeable gravel layer cannot play the role of preventing the loss of fine particles. Therefore, the transition layer is cancelled in this device, and two metal orifice plates are placed instead.
[0007] The metal orifice plate of a conventional permeameter is usually fixed on the wall of the permeation cylinder. Considering that the sampling method of this device is to lift the permeation cylinder, fixing the metal orifice plate on the wall of the permeation cylinder will cause the sample and the permeation cylinder to be lifted together. Therefore, the supporting function of the wall of the permeation cylinder is cancelled in this device, and a supporting frame placed on the base is used to provide the supporting function for the metal orifice plate.
[0008] A plurality of piezometric holes are equidistantly arranged on the side wall of the permeation cylinder. The distance between the piezometric holes is 150 mm. A filter screen is arranged in the piezometric holes. The piezometric holes are connected to a glass piezometer tube through a connecting hose. The inner diameter of the glass piezometer tube is 6 mm. An overflow hole is arranged at the top of the side wall of the permeation cylinder. The overflow hole is 100 mm away from the top end of the permeation cylinder. A water seepage hole is arranged at the bottom of the side wall of the permeation cylinder. The water seepage hole is 50 mm away from the bottom end of the permeation cylinder. The overflow hole and the water seepage hole are respectively connected to a hose, and a stop clamp is arranged on the hose.
[0009] Preferably, the thickness of the lower metal orifice plate is 4 mm and the aperture is 5 mm. Its main function is to support the upper sample without affecting the flow of water. The thickness of the upper metal orifice plate is 1 mm, and the aperture is selected according to the size of the fine particles in the sample, which has the effect of preventing the loss of fine particles.
[0010] Preferably, a sealing ring is arranged between the permeation cylinder and the base to strengthen the seal between the permeation cylinder and the base through the sealing ring.
[0011] Preferably, four fastening screws are vertically and fixedly installed at the edge of the top end of the base. Four limit clamping plates are fixedly installed on the outer wall of the permeation cylinder. The fastening screws cooperate with the limit clamping plates. A nut is threadedly connected to the top end of the fastening screw, and the bottom end of the nut abuts against the limit clamping plate.
[0012] The limit clamping plate limits the fastening screw. By tightening the nut so that the bottom end of the nut abuts against the limit clamping plate, the permeation cylinder can be made to squeeze the sealing ring to achieve a better sealing effect.
[0013] The utility model has the following advantages compared with the prior art:
[0014] 1. In the utility model, the permeation cylinder and the base adopt a split design. A sealing ring is arranged between the permeation cylinder and the base, and the waterproofing at the connection is realized by means of the sealing ring. A limit clamping opening is arranged on the side wall of the permeation cylinder, and fastening screws are fixedly installed at the edge of the top end of the base. By tightening the nut, the nut can be made to abut against the limit clamping opening, so that the bottom end of the permeation cylinder squeezes the sealing ring, making the sealing ring achieve a better sealing effect.
[0015] 2. The metal orifice plate of the present utility model is not placed on the support blocks on the inner wall of the permeation cylinder, but on the support frame located on the base. After the test is completed, the cylinder wall can be directly lifted through the limit bayonet to achieve rapid sample removal.
[0016] The following further describes the present utility model in detail with reference to the accompanying drawings and embodiments. Description of the Drawings
[0017] Figure 1 is a schematic structural diagram of the present utility model.
[0018] Figure 2 is a schematic connection diagram of the base and the permeation cylinder in the present utility model.
[0019] Figure 3 is a schematic structural diagram of the support frame in the present utility model.
[0020] Description of the Reference Numerals in the Drawings:
[0021] 1 - Permeation cylinder; 2 - Overflow hole; 3 - Seepage hole;
[0022] 4 - Manometer hole; 5 - Glass manometer tube; 6 - Connecting hose;
[0023] 7 - Filter screen; 8 - Stopcock; 9 - Limit card board;
[0024] 10 - Tightening screw; 11 - Metal orifice plate; 12 - Support frame;
[0025] 13 - Sealing ring; 14 - Base; 15 - Nut. Detailed Embodiment
[0026] To make the above objects, features, and advantages of the present utility model more apparent and understandable, the following detailed description of the specific embodiments of the present utility model is provided with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present utility model. However, the present utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present utility model. Therefore, the present utility model is not limited by the specific embodiments disclosed below.
[0027] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right", and similar expressions used herein are for illustrative purposes only and do not represent the only implementation manner.
[0028] AsFigures 1 to 3 As shown in the figure, the present utility model provides a constant head permeameter applicable to gravelly soil, which includes a permeation cylinder 1, a support frame 12 and a base 14. The inner diameter of the permeation cylinder 1 is 600 mm, the outer diameter is 640 mm, and the height is 900 mm. The base 14 is cylindrical in shape, with a diameter of 680 mm. There is a groove at the top of the base 14, and the groove is a circular groove with a diameter of 640 mm. The bottom end of the permeation cylinder 1 is movably installed in the groove, and the support frame 12 is movably installed in the permeation cylinder 1. There are two metal orifice plates 11 at the top of the support frame 12.
[0029] In a conventional permeameter, a coarse sand transition layer is laid on the metal orifice plate to prevent the loss of fine particles. Since the test object of this device is gravelly soil with large particle sizes, the permeability coefficient of the coarse sand transition layer may be smaller than that of the test object, resulting in a smaller measured permeation water volume and thus a smaller final result. Laying a more permeable gravel layer cannot prevent the loss of fine particles. Therefore, the transition layer is not provided in this device, but two metal orifice plates 11 are placed instead.
[0030] In a conventional permeameter, the metal orifice plate is usually fixed on the permeation cylinder wall. Considering that the sample removal method of this device is to lift the permeation cylinder, fixing the metal orifice plate on the permeation cylinder wall will cause the sample and the permeation cylinder to be lifted together. Therefore, the support function of the permeation cylinder wall is cancelled in this device, and the support frame 12 placed on the base 14 is used to provide the support for the metal orifice plate 11.
[0031] A plurality of piezometric holes 4 are equidistantly arranged on the side wall of the permeation cylinder 1, with a spacing of 150 mm between the piezometric holes 4. A filter screen 7 is arranged in the piezometric holes 4. The piezometric holes 4 are connected to a glass piezometer tube 5 through a connecting hose 6. The inner diameter of the glass piezometer tube 5 is 6 mm. An overflow hole 2 is opened at the top of the side wall of the permeation cylinder 1, 100 mm away from the top of the permeation cylinder 1. A seepage hole 3 is opened at the bottom of the side wall of the permeation cylinder 1, 50 mm away from the bottom end of the permeation cylinder 1. The overflow hole 2 and the seepage hole 3 are respectively connected to a hose, and a stop clamp 8 is arranged on the hose.
[0032] In this embodiment, the thickness of the lower metal orifice plate 11 is 4 mm and the aperture is 5 mm. Its main function is to support the upper sample without affecting the flow of water. The thickness of the upper metal orifice plate 11 is 1 mm, and the aperture is selected according to the size of the fine particles in the sample, which can prevent the loss of fine particles.
[0033] In this embodiment, a sealing ring 13 is arranged between the permeation cylinder 1 and the base 14 to strengthen the seal between the permeation cylinder 1 and the base 14.
[0034] In this embodiment, four fastening screws 10 are vertically and fixedly installed at the top edge of the base 14. Four limit clamping plates 9 are fixedly installed on the outer wall of the permeation cylinder 1. The fastening screws 10 cooperate with the limit clamping plates 9. A nut 15 is threadedly connected to the top of the fastening screw 10, and the bottom end of the nut 15 abuts against the limit clamping plate 9.
[0035] The limit clamping plate 9 limits the fastening screw 10. Tighten the nut 15 so that the bottom end of the nut 15 abuts against the limit clamping plate 9, which can make the permeation cylinder 1 and the base 14 squeeze the sealing ring 13 to achieve a better sealing effect.
[0036] The usage steps are as follows:
[0037] (I) Instrument preparation and inspection
[0038] 1) Clean the base 14 and place the sealing ring 13. Then use a lifting device to lift the permeation cylinder 1 and place it on the base 14. Rotate the permeation cylinder 1 clockwise so that the fastening screw 10 contacts the limit bayonet 9, and then tighten the nut 15 so that the permeation cylinder 1 squeezes the sealing ring 13 to achieve the purpose of bottom anti-seepage.
[0039] 2) Connect the water supply pipe to the water seepage hole 3 through a hose. Open the stop clamp on the water seepage hole 3 and inject water into the permeation cylinder 1 until the water surface is slightly higher than the water seepage hole 3.
[0040] Observe whether there is water seepage at the connection between the base 14 and the permeation cylinder 1. If water seepage is found, first drain the water in the permeation cylinder, then loosen the nut 15, rotate the permeation cylinder 1 counterclockwise to separate the fastening screw 10 from the limit bayonet 9, lift the permeation cylinder 1, and then apply vaseline on the inner wall of the base 14 and the sealing ring 13. Repeat the operation in step 1 until there is no water seepage at the bottom of the permeation cylinder 1.
[0041] After installing the support frame 12 and the metal hole plate 11, use the connecting hose 6 to connect the pressure measuring hole 4 and the glass manometer tube 5. Then slightly open the stop clamp on the water seepage hole 3 to make the water surface slowly level with the top surface of the metal hole plate 11, and then close the stop clamp on the water seepage hole 3.
[0042] (II) Specimen preparation
[0043] 5) The specimen is prepared by the method of layer-by-layer sampling. Considering that the maximum particle size of the test object of this device is 60 mm, when the layer thickness of the soil sample is too small, the mass and the number of particles of each layer of soil sample are also small, which may lead to a large difference in the gradation of each layer of soil sample weighed, poor uniformity of the prepared soil sample, resulting in unrepresentative test results, and the results measured by multiple samplings will have a large deviation. Therefore, the layer thickness of layer-by-layer sampling of this device is set to 150 mm to ensure that enough particles can be accommodated in the height direction.
[0044] In the diameter direction, if the inner diameter of the infiltration tube is too small and the curvature of the inner wall of the infiltration tube is large, when the size of the soil sample particles is large, the number of particles that can be accommodated on the sample cross section will be very small, and there will be large pores between the infiltration tube wall and the particles that cannot be filled. As a result, during the test, more water will seep away from the large pores between the infiltration tube wall and the soil sample that cannot be filled, resulting in a larger amount of infiltration water measured within a certain period of time, and thus making the final permeability coefficient larger. Therefore, the inner diameter of the infiltration tube of this device is selected to be 600mm, which is 10 times the maximum particle size, to avoid the influence of this phenomenon as much as possible.
[0045] 6) According to the height of 150mm and the diameter of 600mm, calculate and weigh the mass of each layer of soil sample, and then use a compactor to compact the sample to a height of 150mm. Try to ensure that the pressure measuring hole 4 is located in the middle of each layer of soil sample. After each layer of sample is prepared, slightly open the water stop clamp on the seepage hole 3 to make the water surface flush with the top surface of the sample layer to complete the sample saturation.
[0046] After the last layer of sample is saturated, lay a 3 cm thick coarse gravel layer on the upper end of the sample as a buffer layer, and then continue to raise the water level to the overflow hole 2. After water is discharged from the overflow hole 2, close the water stop clamp on the seepage hole 3.
[0047] 7) Let it stand for a few minutes and observe whether the water level of each pressure measuring tube is flush with the overflow hole 2. If it is not flush, it means that there is a gas collection barrier between the pressure measuring hole and the pressure measuring tube. Use a water absorption ball to absorb water and exhaust gas.
[0048] (III) Permeability coefficient test
[0049] 8) Adjust the hose on the seepage hole 3 so that the outer end of the hose is higher than the overflow hole 2, then disconnect the hose on the seepage hole 3 from the water supply pipe, place the water supply pipe in the infiltration tube 1, and allow water to flow into the infiltration tube from the top.
[0050] 9) Lower the height of the outer end of the hose on the seepage hole 3 so that it is located at 1 / 3 of the height of the upper part of the sample, causing a water head difference so that water penetrates into the sample and flows out of the seepage hole 3. In this process, ensure that there is always water overflowing from the overflow hole to ensure a constant water head.
[0051] 10) After the water level in the glass pressure tube 5 is stable, record the water level of each pressure tube, then start the stopwatch, use a measuring cylinder to collect the amount of seepage water within a certain period of time, and repeat the operation once, record the water temperature at the overflow hole 2 and the seepage hole 3, and take the average value.
[0052] 11) Continue to lower the height of the outer end of the hose on the seepage hole 3 to the middle and lower 1 / 3 of the sample, change the water head difference, and then repeat operations 8 to 9.
[0053] 12) Record the test data and calculate the permeability coefficient according to the following table, taking 3 to 4 values with an error of ±2.0×10-n The average value of the data in cm / s is the permeability coefficient of the soil mass at this water temperature.
[0054]
[0055] (IV) Sample Dismantling
[0056] 13) After the test is completed, first drain most of the water in the permeameter 1 through the water seepage hole 3, then remove the connecting hose at the water seepage hole 3, and use a water pump to pump out the water at the bottom of the permeameter 1 through the water seepage hole 3.
[0057] 14) Loosen the nut 15 on the fastening screw 10, rotate the permeameter 1 to separate the limit bayonet 9 from the fastening screw 10, remove the connecting hose 6 between the piezometric hole 4 and the glass piezometer tube 5, separate the glass piezometer tube 5 from the permeameter 1, fix it with a steel cable to the limit bayonet 9, and lift the permeameter 1 upward through a hoisting device to separate it from the internal sample, realizing rapid sample dismantling.
[0058] The above description is only a preferred embodiment of the present invention and does not impose any limitation on the present invention. Any simple modification, change, and equivalent change made to the above embodiments according to the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims
1. A constant head permeameter suitable for gravel soil, characterized in that: The invention comprises a permeation cylinder (1), a support frame (12) and a base (14); the top of the base (14) is provided with a groove; the bottom of the permeation cylinder (1) is movably mounted in the groove; the support frame (12) is movably mounted in the permeation cylinder (1); the top of the support frame (12) is provided with two metal orifice plates (11); a plurality of pressure measuring holes (4) are equidistantly provided on the side wall of the permeation cylinder (1); a filter screen (7) is provided in each of the pressure measuring holes (4); the pressure measuring holes (4) are connected to a glass pressure measuring tube (5) via a connecting hose (6); an overflow hole (2) is provided on the top of the side wall of the permeation cylinder (1); a seepage hole (3) is provided on the bottom of the side wall of the permeation cylinder (1); the overflow hole (2) and the seepage hole (3) are respectively connected to a hose; a water stop clamp (8) is provided on the hose.
2. A constant head permeameter suitable for gravel soil according to claim 1, characterized in that: A sealing ring (13) is provided between the permeation cylinder (1) and the base (14).
3. A constant head permeameter suitable for gravel soil according to claim 2, characterized in that: A plurality of fastening screws (10) are vertically fixedly installed at the top edge of the base (14), and a plurality of limit clamps (9) are fixedly installed on the outer wall of the permeation cylinder (1). The fastening screws (10) cooperate with the limit clamps (9), and a nut (15) is threadedly connected to the top of the fastening screw (10), and the bottom end of the nut (15) is tightly pressed against the limit clamp (9).
4. A constant head permeameter suitable for gravel soil according to claim 1, characterized in that: The groove is a circular groove, the diameter of which is 640 mm; the base (14) is cylindrical in shape, and the diameter of which is 680 mm.
5. A constant head permeameter suitable for gravel soil according to claim 4, characterized in that: The infiltration cylinder (1) has an inner diameter of 600 mm, an outer diameter of 640 mm and a height of 900 mm.
6. A constant head permeameter suitable for gravel soil according to claim 5, characterized in that: The overflow hole (2) is 100 mm away from the top end of the infiltration tube (1), and the seepage hole (3) is 50 mm away from the bottom end of the infiltration tube (1).
7. A constant water head permeameter suitable for gravel soil according to claim 1, characterized in that: The spacing between the pressure measuring holes (4) is 150 mm, and the inner diameter of the glass pressure measuring tube (5) is 6 mm.
8. A constant head permeameter suitable for gravel soil according to claim 1, characterized in that: The metal perforated plate (11) located at the bottom has a thickness of 4 mm and a hole diameter of 5 mm, and the metal perforated plate (11) located at the top has a thickness of 1 mm.