Portable under-pressure variable water head permeability test device

Abstract

The utility model discloses a portable under-pressure variable head permeability test device which comprises a permeability test barrel and a pressure control box, the penetration test barrel comprises a soil container shell, an inner supporting ring is arranged on the inner wall of the lower end of the soil container shell, an outer connecting ring is arranged on the outer wall of the lower end of the soil container shell, a sealing cover is arranged at the upper end of the soil container shell, and a permeable plate and geotechnical cloth are arranged in the soil container shell; the sealing cover is provided with an opening in a projection area of the soil container shell, the upper end face of the sealing cover is connected with a water storage shell at the opening, and a pipe connector is arranged at the upper end of the water storage shell; the soil container shell and the sealing cover are fastened and sealed; the pressure control box comprises an air pump, air pressure regulation and control equipment and an output port which are connected in sequence, and high-pressure air is output to the pipe connector through the output port. According to the device, the permeability coefficient of the improved muck on the shield site can be measured in real time.

Description

Technical Field

[0001] The utility model relates to the technical field of soil detection, in particular to a portable permeability testing device with pressure-variable water head. Background Art

[0002] Currently, shield tunneling has become one of the mainstream construction methods in urban subway tunnel construction due to its high degree of mechanization, high excavation efficiency, and high safety. Shield tunneling is mainly divided into earth pressure balance shields and slurry balance shields based on the working principle. The earth pressure balance shield method is widely used in subway tunnel construction in various strata, including sandy strata, clay strata, granite strata, and composite strata, due to its advantages such as wide applicability and small construction site area. The earth pressure balance shield balances the water and soil pressure on the excavation face through the earth pressure of the slag in the soil compartment. At the same time, the screw conveyor controls the soil discharge speed to ensure the dynamic balance of the earth pressure at the face. Therefore, the ideal state of the slag during transportation should be a plastic flow state.

[0003] During earth pressure balance shield construction, the undisturbed soil produced by the cutterhead often fails to meet the safety requirements of shield construction, failing to provide sufficient support for the tunnel face and ensuring smooth discharge of shield debris. When encountering complex working conditions such as water-rich strata, large-grained gravel strata, and upper soft and lower hard strata, the water and soil pressure at the excavation face and the pressure within the shield machine's soil compartment are difficult to achieve equilibrium due to poor gradation, loose soil, low cementation, and poor self-stability. This can lead to construction problems such as excavation face instability, soil compartment ballasting, and screw conveyor gushing.

[0004] To improve the Earth Pressure Balance Shield's adaptability to the ground, control the chamber pressure, and increase soil removal efficiency, the soil removed by the shield needs to be modified. During shield tunneling, additives such as foaming agents, bentonite slurry, high molecular weight polymers, and water are injected into the cutterhead face, chamber, and screw conveyor to impart good fluidity, appropriate plasticity, low shear strength and adhesion, minimal permeability, and a certain degree of compressibility to the excavated soil.

[0005] In water-rich sandy strata, due to their poor particle gradation, high porosity, and high permeability, water and soil separation is prone to occur when an earth pressure balance shield tunnel penetrates these strata. This can lead to water, sand, and mud spraying at the screw conveyor discharge port, a phenomenon known as "gushing." This makes it difficult to ensure the normal excavation of the shield machine and can even cause major disasters such as excavation face instability. Therefore, to prevent problems such as screw conveyor gushing and excavation face instability, the slag soil in the shield soil must have good water-stopping properties, which requires controlling the permeability coefficient of the slag soil in the soil compartment.

[0006] Existing research on the permeability coefficient of shield-improved soil focuses on indoor test measurements. The test operation is complicated and it is difficult to truly reflect the actual permeability changes of the improved soil at the shield site. There is a lack of portable permeability test equipment suitable for earth pressure balance shield sites. Utility Model Content

[0007] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a portable permeability testing device with pressure-variable water head, so as to realize the timely measurement and judgment of the permeability coefficient and anti-seepage characteristics of shield-improved slag.

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

[0009] A portable permeability test device with variable pressure head comprises a permeability test barrel and a pressure control box; the permeability test barrel comprises a soil container shell, an inner support ring is provided on the inner wall of the lower end of the soil container shell, an outer connecting ring is provided on the outer wall of the lower end of the soil container shell, a sealing cover is provided on the upper end of the soil container shell, and a permeable plate and geotextile are provided in the soil container shell; the sealing cover is provided with an opening in the projected area of ​​the soil container shell, the upper end surface of the sealing cover is connected to a water storage shell at the opening, and a pipe connector is provided on the upper end of the water storage shell; the soil container shell and the sealing cover are fastened by fasteners, and the soil container shell and the sealing cover are sealed by a seal; the pressure control box comprises an air pump, an air pressure regulating device, and an output port connected in sequence, and outputs high-pressure gas to the pipe connector via the output port.

[0010] Furthermore, the soil container shell and the water storage shell are cylindrical;

[0011] Specifically, a sealing opening is provided at the upper end of the water storage shell, a threaded opening is provided at the upper end of the water storage shell, the threaded opening of the water storage shell is threadedly connected to the pipe connector, and the threaded opening of the water storage shell is sealed to the pipe connector.

[0012] Furthermore, the outer connecting ring, the inner supporting ring and the sealing cover are all in an annular shape;

[0013] Specifically, the axis of the soil container shell, the axis of the water storage shell, and the axis of the sealing cover coincide with each other;

[0014] Specifically, the diameter of the central hole of the sealing cover is smaller than the inner diameter of the soil container shell, and the water storage shell is connected to the central hole of the sealing cover.

[0015] Furthermore, the water storage shell and the sealing cover are integrally formed;

[0016] Specifically, the water storage shell, sealing cover and soil container shell are all made of hard transparent plastic.

[0017] Furthermore, an upper permeable plate, an upper geotextile, a lower geotextile, and a lower permeable plate are arranged in the soil container shell from top to bottom, and the space between the upper geotextile and the lower geotextile is used to place the test soil sample.

[0018] Furthermore, the upper water-permeable plate and the lower water-permeable plate are circular plates provided with water-permeable holes, the outer diameter of the circular plate is equal to the inner diameter of the earth container shell, and the lower water-permeable plate sits on the inner support ring.

[0019] Furthermore, the sealing cover is provided with at least three upper connecting holes, the outer connecting ring is provided with lower connecting holes corresponding to the upper connecting holes, and the fasteners include fixing bolts and nuts, and the fixing bolts pass through the upper connecting holes, the lower connecting holes, and the connecting nuts.

[0020] Furthermore, the air pressure regulating device includes a buffer container, a one-way valve, an output container, a pressure reducing valve, and a pressure controller;

[0021] Specifically, the air pump, buffer container, one-way valve, output container, pressure reducing valve, and output port are connected in sequence; the output container is connected to a pressure sensor, and the pressure controller is electrically connected to the air pump and the pressure sensor;

[0022] Specifically, the pressure control box further includes a battery; the air pump is an electric air pump, and the battery is electrically connected to the air pump and the pressure controller.

[0023] Furthermore, the output port is connected to a pipe connector through an air pipeline and a safety valve.

[0024] Furthermore, the pressure control box further comprises a box body; the air pump, buffer container, one-way valve, output container, pressure reducing valve, battery, and pressure controller are all arranged in the box body;

[0025] Specifically, a digital display screen, a pressure gauge, a start switch, a control knob of a pressure reducing valve, and an output port are provided on the surface of the box; the digital display screen is electrically connected to the pressure controller, and the digital display screen is provided with a button; the pressure gauge is connected to the pressure reducing valve and the output port by pipelines; the start switch is connected in series with the battery power supply circuit.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The utility model can realize the real-time measurement of the permeability coefficient of the improved slag at the shield tunneling site; compared with the existing permeability indoor test, it reduces the test time and realizes the tracking measurement of the permeability change law of the slag at the shield tunneling site; it effectively prevents the occurrence of construction problems such as screw conveyor gushing and soil cabin pressure imbalance.

[0028] 2. The pressure control device of the present invention can set the maximum and minimum output pressures by itself, thereby changing the permeation water pressure during the test and conducting a variable head permeation test.

[0029] 3. The utility model solves the problem that existing osmotic instruments cannot finely adjust the osmotic pressure by adopting an osmotic pressure control method that combines a pressure controller with a pressure reducing valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural diagram of the penetration test barrel in the utility model;

[0031] Figure 2 It is a cross-sectional view of the penetration test barrel in the utility model;

[0032] Figure 3 This is a schematic structural diagram of the pressure control box in the utility model;

[0033] Figure 4 It is a schematic diagram of the internal connection structure of the pressure control box in the utility model.

[0034] Figure: 1. Pipe connector; 2. Water storage shell; 3. Sealing cover; 4. Upper permeable plate; 5. Upper geotextile; 6. Soil container shell; 7.1. External connecting ring; 7.2. Inner support ring; 8. Lower permeable plate; 8.1. Permeable hole; 9. Lower geotextile; 10. Seal; 11. Fixing bolts.

[0035] 12. Pressure gauge; 13. Pressure reducing valve; 14. Output port; 15. Start switch; 16. Digital display; 17. Battery; 18. Air pump; 19. Buffer container; 20. One-way valve; 21. Output container; 22. Pressure controller; 23. Air line;

[0036] 30. Test soil sample; 40. Water. DETAILED DESCRIPTION

[0037] 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 embodiments described 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. Example 1:

[0038] See also Figures 1 to 4The utility model provides a portable permeation test device with variable pressure and water head, which includes a permeation test barrel and a pressure control box. The maximum and minimum values ​​of the output pressure of the pressure control box can be set by yourself. When the output pressure is lower than the set minimum value, the device automatically replenishes the pressure to ensure that the permeation water pressure during the test is not lower than the set minimum value, that is, to ensure a certain head pressure.

[0039] The permeability test barrel includes a soil container shell 6, an inner support ring 7.2 is provided on the inner wall of the lower end of the soil container shell 6, an outer connecting ring 7.1 is provided on the outer wall of the lower end of the soil container shell 6, a sealing cover 3 is provided on the upper end of the soil container shell 6, an opening is provided on the projection area of ​​the soil container shell 6, the upper end surface of the sealing cover 3 is connected to the water storage shell 2 at the opening, and a pipe connector 1 is provided on the upper end of the water storage shell 2; an upper permeable plate 4, an upper geotextile 5, a lower geotextile 9, and a lower permeable plate 8 are provided in the soil container shell 6 from top to bottom, the soil container shell 6 and the sealing cover 3 are fastened by fasteners, and the soil container shell 6 and the sealing cover 3 are sealed by a seal 10.

[0040] Specifically, the earth container shell 6 and the water storage shell 2 are cylindrical, the upper end of the water storage shell 2 is provided with a seal, the upper end of the water storage shell 2 is provided with a threaded opening, the threaded opening of the water storage shell 2 is threadedly connected to the pipe connector 1, and the threaded opening of the water storage shell 2 and the pipe connector 1 are sealed by a sealing ring or raw tape.

[0041] Specifically, the outer connecting ring 7.1, the inner supporting ring 7.2, and the sealing cover 3 are all annular. The axis of the soil container shell 6, the axis of the water storage shell 2, and the axis of the sealing cover 3 coincide with each other. The center hole diameter of the sealing cover 3 is smaller than the inner diameter of the soil container shell 6. The water storage shell 2 is connected to the center hole of the sealing cover 3.

[0042] Specifically, the water storage shell 2 and the sealing cover 3 are integrally formed.

[0043] Specifically, the water storage shell 2, the sealing cover 3, and the soil container shell 6 are all made of hard transparent plastic, which is convenient for observing the internal conditions.

[0044] Specifically, the upper permeable plate 4 and the lower permeable plate 8 are circular plates provided with permeable holes 8.1, the outer diameter of the circular plate is equal to the inner diameter of the earth container shell 6, and the lower permeable plate 8 sits on the inner support ring 7.2.

[0045] Specifically, the sealing cover 3 is provided with at least three upper connection holes, the outer connection ring 7.1 is provided with lower connection holes corresponding to the upper connection holes, and the fasteners include fixing bolts 11 and nuts. The fixing bolts 11 pass through the upper connection holes, the lower connection holes, and the connection nuts.

[0046] Specifically, the sealing member 10 is a rubber sealing ring.

[0047] The pressure control box includes an air pump 18, a buffer container 19, a one-way valve 20, an output container 21, a pressure reducing valve 13, and an output port 14, which are connected in sequence. It also includes a battery 17 and a pressure controller 22. The air pump 18 is an electric air pump. The battery 17 is electrically connected to the air pump 18 and the pressure controller 22. The output container 21 is connected to a pressure sensor, and the pressure controller 22 is electrically connected to the air pump 18 and the pressure sensor.

[0048] The air pump 18 is used to generate air pressure flow.

[0049] The buffer container 19 is used to reduce the pulse amplitude of the gas and improve the stability of the system.

[0050] The one-way valve 20 prevents the airflow from flowing backward.

[0051] The output container 21 stores high-pressure gas, and the pressure sensor detects the gas pressure in the output container 21 .

[0052] The pressure controller 22 adjusts the power of the air pump 18 according to the detection data of the pressure sensor.

[0053] The pressure reducing valve 13 is used to control the output pressure.

[0054] The output port 14 is connected to the pipe connector 1 through the air pipeline 23 and the safety valve.

[0055] Specifically, the pressure control box also includes a box body, and the air pump 18, buffer container 19, one-way valve 20, output container 21, pressure reducing valve 13, battery 17, and pressure controller 22 are all arranged in the box body. A digital display screen 16, a pressure gauge 12, a start switch 15, a control knob of the pressure reducing valve 13, and an output port 14 are set on the surface of the box body; the digital display screen 16 is electrically connected to the pressure controller 22, and the digital display screen 16 is provided with a button for controlling the target pressure of the gas in the output container 21; the pressure gauge 12 is connected to the pressure reducing valve 13 and the output port 14 by a pipeline, and the pressure gauge 12 is used to display the output pressure; the start switch 15 is connected in series with the battery power supply circuit to control the start of the pressure control box.

[0056] It should be noted that the air pump 18, buffer container 19, one-way valve 20, output container 21, pressure reducing valve 13, battery 17, digital display 16, pressure gauge 12, start switch 15, pressure reducing valve 13, pressure sensor, and pressure controller 22 themselves belong to the existing technology and can be purchased. The pressure controller 22 can be a programmable control device such as a single-chip microcomputer and a PLC. Example 2:

[0057] Based on Example 1, this example provides a method for using a portable pressure-variable water head permeability test device, including the following steps:

[0058] S1. To timely determine the permeability coefficient of shield excavation soil and avoid the influence of the loss of improver on the test results, 30 test soil samples were taken from the position where the belt conveyor transported the soil to the bucket to ensure that the test soil sample was the latest improved soil discharged during shield excavation.

[0059] S2. Place the lower permeable board 8 and the lower geotextile 9 in the soil container shell 6 in sequence, fill it with the test soil sample 30, place the upper geotextile 5 and the upper permeable board 4 in sequence on top of the test soil sample 30, and tighten the sealing cover 3 and the soil container shell 6 with fixing bolts 11 and nuts.

[0060] S3. In this embodiment, the water storage shell 2 has a capacity of 500 ml. Use a water line to connect the pipe connector 1 to the on-site faucet and inject water into the water storage shell 2. First, saturate the test soil sample 30. Stop injecting water until the water storage shell 2 is full of water.

[0061] S4. Use the air line 23 and the safety valve to connect the pipe connector 1 to the output port 14 of the pressure control box.

[0062] Set the pressure of the output container 21 of the pressure control box to 450kPa, press the start button to start pressurization, and when the pressure of the output container 21 reaches 450kPa, adjust the pressure reducing valve 13 to stabilize the output pressure at 400kPa, open the safety valve, and start the test;

[0063] During the test, the time required for 500 ml of water to completely penetrate was recorded; if the complete penetration was not completed within 5 minutes, the amount of water that penetrated within 5 minutes was recorded and the permeability coefficient of the improved soil was calculated.

[0064] It should be noted that the connection between the water pipeline, the gas pipeline 23 and the pipe connector 1 is a sealed connection, and the pipe connector 1 itself belongs to the existing technology, such as a VCR connector.

[0065] All components not discussed in detail in this application and the connection methods of the components in this application are well-known technologies in the technical field and can be directly applied without further explanation.

[0066] In this utility model, the term "plurality" refers to two or more, unless otherwise specified. Terms such as "installed," "connected," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean fixed, removable, or integral; "connected" can mean directly or indirectly through an intermediary. Those skilled in the art will understand the specific meanings of these terms in this utility model based on specific circumstances.

[0067] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as "up", "down", "left", "right", "front" and "back" are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0068] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A portable water head permeability test device with pressure variation, characterized in that: Including penetration test barrel and pressure control box; The permeability test barrel comprises a soil container shell, an inner support ring is provided on the inner wall of the lower end of the soil container shell, an outer connection ring is provided on the outer wall of the lower end of the soil container shell, a sealing cover is provided on the upper end of the soil container shell, and a permeable board and geotextile are provided in the soil container shell; The sealing cover is provided with an opening in the projection area of ​​the earth container shell, the upper end surface of the sealing cover is connected to the water storage shell at the opening, and the upper end of the water storage shell is provided with a pipe connector; The soil container shell and the sealing cover are fastened by fasteners, and the soil container shell and the sealing cover are sealed by a sealing member; The pressure control box includes an air pump, an air pressure regulating device, and an output port which are connected in sequence, and outputs high-pressure gas to the pipe connector through the output port.

2. A portable permeability test device with pressure-variable water head according to claim 1, characterized in that: The soil container shell and water storage shell are cylindrical; The upper end of the water storage shell is provided with a seal, the upper end of the water storage shell is provided with a threaded opening, the threaded opening of the water storage shell is threadedly connected to the pipe connector, and the threaded opening of the water storage shell is sealed with the pipe connector.

3. A portable permeability test device with pressure-variable water head according to claim 2, characterized in that: The outer connecting ring, inner supporting ring and sealing cover are all in annular shape; The axis of the soil container shell, the axis of the water storage shell, and the axis of the sealing cover coincide with each other; The diameter of the central hole of the sealing cover is smaller than the inner diameter of the soil container shell, and the water storage shell is connected to the central hole of the sealing cover.

4. A portable permeability test device with pressure-variable water head according to claim 3, characterized in that: The water storage shell and the sealing cover are integrally formed; The water storage shell, the sealing cover and the soil container shell are all made of hard transparent plastic.

5. The portable permeability test device with pressure-variable water head according to claim 1, characterized in that: An upper permeable plate, an upper geotextile, a lower geotextile, and a lower permeable plate are arranged in the soil container shell from top to bottom, and the space between the upper geotextile and the lower geotextile is used to place the test soil sample.

6. The portable permeability test device with pressure-variable water head according to claim 5, characterized in that: The upper permeable plate and the lower permeable plate are circular plates provided with permeable holes. The outer diameter of the circular plate is equal to the inner diameter of the earth container shell. The lower permeable plate sits on the inner support ring.

7. The portable permeability test device with pressure-variable water head according to claim 1, characterized in that: The sealing cover is provided with at least three upper connection holes, the outer connection ring is provided with lower connection holes corresponding to the upper connection holes, and the fasteners include fixing bolts and nuts, and the fixing bolts pass through the upper connection holes and the lower connection holes and are connected to the nuts.

8. The portable permeability test device with variable pressure head according to claim 1, characterized in that: The air pressure control equipment includes a buffer container, a one-way valve, an output container, a pressure reducing valve, and a pressure controller; The air pump, buffer container, one-way valve, output container, pressure reducing valve, and output port are connected in sequence; the output container is connected to a pressure sensor, and the pressure controller is electrically connected to the air pump and pressure sensor; The pressure control box also includes a battery; the air pump is an electric air pump, and the battery is electrically connected to the air pump and the pressure controller.

9. The portable permeability test device with pressure-variable water head according to claim 8, characterized in that: The output port is connected to the pipe connector through an air pipeline and a safety valve.

10. The portable permeability test device with pressure-variable water head according to claim 8, characterized in that: The pressure control box also includes a box body; the air pump, buffer container, one-way valve, output container, pressure reducing valve, battery, and pressure controller are all arranged in the box body; A digital display screen, a pressure gauge, a start switch, a control knob for a pressure reducing valve, and an output port are provided on the surface of the box; the digital display screen is electrically connected to the pressure controller and is provided with a button; the pressure gauge is connected to the pressure reducing valve and the output port by pipelines; the start switch is connected in series with the battery power supply circuit.

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