Silt infiltration and infiltration deformation device and method based on dynamic negative pressure working conditions

Abstract

The present invention belongs to the field of geotechnical testing for water conservancy projects, and specifically relates to a device and method for measuring silt infiltration and infiltration deformation based on a dynamic negative pressure working condition. The device comprises a liftable water supply tank, a sample tube, a pressure stabilizing tube, and a vacuum pump, connected in sequence. A negative pressure system, a water-gas separation system, and a measurement system are provided between or on the sample tube, the pressure stabilizing tube, and the vacuum pump. The negative pressure system comprises a negative pressure sensor, a dynamic negative pressure generator, and a negative pressure regulator; the water-gas separation system comprises an annular water-gas separator and a three-way pipe; and the measurement system comprises a pressure sensor, a volumetric flask, and a vacuum pressure gauge. The present invention can monitor in real time the changing process of infiltration deformation, such as piping deformation of silt surface particles, soil flow deformation, or combined deformation of piping and soil flow, under different water heads. This allows for more scientific and reasonable determination of control indicators such as the critical slope and failure slope of silt infiltration deformation, which is beneficial for ensuring the safety and stability of anti-seepage silt embankment projects.

Description

Technical Field

[0001] The invention belongs to the field of geotechnical tests for water conservancy projects, and in particular relates to a device and method for silt infiltration and infiltration deformation based on a dynamic negative pressure working condition. Background Art

[0002] Silt is a transitional soil composed of uniform, fine particles with low plasticity. Its properties are similar to those of silt sand, but it also has the characteristics of clay. Silt is often used to construct seawalls along the Qiantang River, but leakage and permeability damage to these seawalls are common due to the effects of waves and tides.

[0003] Studies have shown that waves and tides will generate relative negative pressure, which will accelerate the deterioration of silt. However, the current soil permeameter can only simulate the impact of normal seepage water pressure difference on the infiltration and seepage deformation of the soil, and cannot simulate the adverse effects of the combined action of surface dynamic negative pressure and seepage water pressure generated by high and low tides. The test results are inconsistent with reality, which is not conducive to the anti-seepage safety of embankment projects.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a silt infiltration and infiltration deformation device and method based on a dynamic negative pressure working condition.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions, comprising a liftable water supply tank, a sample tube, a pressure stabilizing tube, and a vacuum pump connected in sequence, wherein a negative pressure system, a water-gas separation system, and a measurement system are provided between the sample tube, the pressure stabilizing tube, and the vacuum pump or on the device.

[0008] The negative pressure system includes a negative pressure sensor, a dynamic negative pressure generator and a negative pressure regulator; the water-gas separation system includes an annular water-gas separator and a three-way pipe; the measuring system includes a pressure sensor, a volumetric flask and a vacuum pressure gauge; the three-way pipe is respectively connected to the volumetric flask, the annular water-gas separator and the pressure stabilizing cylinder, and the annular water-gas separator is respectively connected to the sample cylinder, the three-way pipe and the pressure stabilizing cylinder.

[0009] The sample tube includes a sample tube base, a sample tube body and a sample tube cover. A metal orifice plate is provided between the sample tube base and the sample tube body. A metal orifice plate is provided inside the sample tube body. A hollow flower tube is provided between the metal orifice plate on the top surface of the sample in the sample tube and the sample tube cover. The liftable water supply box is connected to the sample tube base, and a ball valve switch is provided between the liftable water supply box and the sample tube base.

[0010] The negative pressure sensor is arranged on the cover of the sample tube, and a ball valve switch is arranged between the negative pressure sensor and the cover of the sample tube.

[0011] A scale and a camera are provided on one side of the sample tube body.

[0012] A ball valve switch and a permeable stone core are provided between the sample tube and the pressure sensor.

[0013] A three-way switch is provided between the sample cylinder and the dynamic negative pressure generator, and a three-way switch is provided between the annular water-gas separator and the pressure stabilizing cylinder.

[0014] A plurality of pressure sensors are provided on both sides of the sample cylinder, the dynamic negative pressure generator is provided between the sample cylinder and the pressure stabilizing cylinder, and the vacuum pressure gauge and the negative pressure regulator are provided between the pressure stabilizing cylinder and the vacuum pump.

[0015] The volumetric flask includes a first volumetric flask, a second volumetric flask and a third volumetric flask. The openings of the first volumetric flask, the second volumetric flask and the third volumetric flask are all provided with bottle stoppers. The three-way pipe includes an air extraction three-way pipe and a water passage three-way pipe. The opening of the volumetric flask is provided with a bottle stopper. A three-way switch is provided between the air extraction three-way pipe and the bottle stopper, and the air extraction three-way pipe is communicated with a pressure stabilizing cylinder. A ball valve switch is provided between the air extraction three-way pipe and the pressure stabilizing cylinder.

[0016] A ball valve switch is provided between the water-passing three-way pipe and the bottle stopper, and the water-passing three-way pipe is communicated with the annular water-gas separator.

[0017] A method for using a silt infiltration and infiltration deformation device based on a dynamic negative pressure working condition comprises the following steps:

[0018] a: Check the sealing of the instrument

[0019] b: Preparation of sample

[0020] c: Sample saturated with negative pressure

[0021] 1) Place the filter membrane, metal orifice plate, and hollow flower tube on the top of the sample cylinder in sequence. Place the filter membrane on the metal orifice plate at the base of the sample cylinder. Install and tighten the flanges between the base and the cylinder, and between the cylinder and the cylinder cover, and seal them with seals. Connect the three-way switch between the pressure-stabilizing cylinder and the sample cylinder cover and open it. Close the ball valve switch on the sample cylinder cover and the side of the sample cylinder. Close the ball valve switch between the pressure-stabilizing cylinder and the three-way switch between the pressure-stabilizing cylinder and the exhaust three-way pipe, and close the three-way switch between the pressure-stabilizing cylinder and the annular water-gas separator.

[0022] 2) Adjust the water supply tank so that the water level is slightly higher than the bottom surface of the sample tube base. Slowly open the ball valve switch on the side of the sample tube base. After water flows out of the exhaust hole on the sample tube base, close the ball valve switch.

[0023] 3) Turn on the vacuum pump and adjust the negative pressure regulator to make the vacuum pressure gauge reach 20KPa. Continue to pump air for 1 hour. Slightly open the ball valve switch on the base of the sample tube to allow a very thin stream of water to slowly flow into the sample tube. Continue to pump air and maintain the pressure value of the vacuum pressure gauge unchanged until the water level in the sample tube overflows the metal orifice plate on the surface of the sample. Then slowly raise the liftable water supply tank until its water level is slightly higher than the water level of the metal orifice plate on the surface of the sample tube. Turn off the vacuum pump.

[0024] 4) Slowly open the three-way switch on the cover of the sample tube to connect it to the atmosphere, and open the negative pressure regulator until the pressure on the vacuum pressure gauge reaches zero, indicating that the sample is saturated;

[0025] d: Test method under dynamic negative pressure conditions

[0026] 1) Remove the metal orifice plate and filter membrane on the top surface of the sample in the sample tube, replace them with a metal mesh sheet (diamond-shaped, 10mm*5mm), then open the ball valves on both sides of the sample tube in sequence from bottom to top, and install a pressure sensor on the side of the sample tube underwater; turn on the camera on the side of the sample tube, and open the ball valve between the sample tube cover and the negative pressure sensor;

[0027] 2) Open the ball valve between the sample tube and the annular water-gas separator, connect the annular water-gas separator and the pressure-stabilizing tube, open the ball valve between the pressure-stabilizing tube and the three-way exhaust pipe, open the ball valves between the stoppers of the three volumetric flasks and the three-way water pipe, and open the three-way switch between the three volumetric flasks and the three-way exhaust pipe; start the vacuum pump to evacuate the entire test device, adjust the negative pressure regulator between the vacuum pump and the vacuum pressure gauge, and when the negative pressure sensor on the sample tube cover and the vacuum pressure gauge reach the required negative pressure value, continue to maintain the vacuum degree;

[0028] 3) Close the ball valves between the second and third volumetric flasks and the water three-way pipe, and slowly raise the liftable water supply tank by 15-20 cm each time. After the water level in the liftable water supply tank is equal to the water level in the sample tube and wait for 10 minutes, raise the liftable water supply tank again until water flows out of the overflow port on one side of the tube body, maintaining a constant head difference to form the initial infiltration slope; turn on the dynamic negative pressure generator;

[0029] 4) After the water flow rate stabilizes, close the ball valve between the first volumetric flask and the water three-way pipe. At the same time, open the ball valve between the second volumetric flask and the water three-way pipe. Start the stopwatch and read the pressure sensors on both sides of the sample cylinder.

[0030] 5) Close the connection between the first volumetric flask and the three-way exhaust pipe, and connect the first volumetric flask to the atmosphere; pull out the cap of the first volumetric flask, pour out the water in the bottle, reinstall the first volumetric flask, close the three-way switch channel on the first volumetric flask that connects to the atmosphere, and connect the three-way exhaust pipe to the first volumetric flask for next use;

[0031] 6) When the second volumetric flask receives a certain amount of water, close the ball valve between the second volumetric flask and the water three-way pipe and start counting the seconds. At the same time, open the ball valve between the third volumetric flask and the water three-way pipe and start counting the seconds. Again, read the pressure sensor readings on both sides of the sample cylinder.

[0032] 7) Close the connection between the second volumetric flask and the three-way exhaust pipe, connect the second volumetric flask to the atmosphere, remove the cap of the second volumetric flask, weigh the amount of water in the second volumetric flask and pour out all the water in the flask, reinstall the second volumetric flask, close the three-way switch channel on the second volumetric flask that connects to the atmosphere, and connect the three-way exhaust pipe to the second volumetric flask for next use;

[0033] 8) Repeat steps 6) and 7) using the second and third volumetric flasks alternately;

[0034] 9) Each time the volumetric flask is filled with water, measure and record the changes in water temperature, room temperature, and the value of the pressure sensor on the side of the sample tube, and weigh and measure the turbidity of the seeping water;

[0035] 10) Read the water seepage volume several times continuously. When the pressure sensor value, water seepage volume, and turbidity are basically stable, you can move on to the next level of water head. After increasing the water head and observing that the pressure sensor readings on both sides of the sample tube are basically stable, repeat the test according to the above steps 4) to 9) until the test fails or the water head can no longer be increased. The test can then be terminated.

[0036] e: Test method under normal seepage water pressure condition

[0037] Remove the negative pressure system and water-gas separation system. The remaining test steps are the same as those under dynamic negative pressure conditions.

[0038] f: Penetration damage judgment method

[0039] Observe the changes in soil suspension, combine with the turbidity measurement of seepage water, and make a comprehensive judgment based on the changes in the slope of the relationship curve between seepage gradient and seepage velocity (lgi ~lgv).

[0040] The beneficial effects of the present invention are as follows:

[0041] (1) A negative pressure system is set up to check the sealing of the equipment system, which can be combined with the normal seepage water pressure to truly simulate the seepage force under the action of waves and tides;

[0042] (2) Through the combined design of the negative pressure system and the measurement system, water vapor separation and seepage water collection under long-term continuous test conditions can be achieved;

[0043] (3) The changing process of seepage deformation, such as piping deformation of silt surface particles, soil flow deformation, or combined deformation of piping and soil flow, can be monitored in real time under different water heads, so as to more scientifically and rationally determine the control indicators such as the critical slope and failure slope of silt seepage deformation, which is beneficial to ensure the safety and stability of anti-seepage of silt embankment projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic structural diagram of a silt infiltration and infiltration deformation device based on a dynamic negative pressure working condition according to the present invention;

[0045] Figure 2 The graph of the relationship between the seepage gradient and the seepage velocity in the embodiment;

[0046] Among them, the numbers: 101 is a liftable water supply box, 201 is the body of the sample tube, 207 is a permeable stone core, 208 is an overflow port, 215 is a pressure sensor, 223 is a camera, 224 is a scale, 230 is the base of the sample tube, 235 is a metal orifice plate, 236 is a hollow flower tube, 240 is the cover of the sample tube, 244 is a negative pressure sensor, 301 is a pressure stabilizing tube, 312 is a vacuum pressure gauge, 313 is a negative pressure regulator, 314 is a vacuum pump, 320 is an annular water-gas separator, 325 is a dynamic negative pressure generator, 401 is a first volumetric flask, 402 is a second volumetric flask, 403 is a third volumetric flask, 404 is a bottle stopper, 407 is a ball valve switch, 410 is a three-way switch, 413 is an air extraction three-way pipe, and 419 is a water passage three-way pipe. DETAILED DESCRIPTION

[0047] The technical solution of the present invention will be further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0048] like Figure 1 As shown, a silt infiltration and infiltration deformation device based on a dynamic negative pressure working condition includes a liftable water supply box 101, a sample tube, a pressure stabilizing tube 301 and a vacuum pump 314 connected in sequence, and a negative pressure system, a water-gas separation system and a measurement system are provided between the sample tube, the pressure stabilizing tube 301 and the vacuum pump 314 or on the device. The negative pressure system includes a negative pressure sensor 244, a dynamic negative pressure generator 325 and a negative pressure regulator 313; the water-gas separation system includes an annular water-gas separator 320 and a three-way pipe; the measurement system includes a pressure sensor 215, a volumetric flask and a vacuum pressure gauge 312; the three-way pipe is respectively connected to the volumetric flask, the annular water-gas separator 320 and the pressure stabilizing tube 301, and the annular water-gas separator 320 is respectively connected to the sample tube, the three-way pipe and the pressure stabilizing tube 301.

[0049] The sample tube includes a sample tube base 230, a sample tube body 201, and a sample tube cover 240. A metal orifice plate 235 is installed between the sample tube base 230 and the sample tube body 201. The metal orifice plate 235 is also installed inside the sample tube body 201. The liftable water supply tank 201 is connected to the sample tube base 230, and a ball valve switch 407 is installed between the liftable water supply tank 101 and the sample tube base 230. A negative pressure sensor 244 is installed on the sample tube cover 240, and a ball valve switch 407 is installed between the negative pressure sensor 244 and the sample tube cover 240. A scale 224 and a camera 223 are installed on one side of the sample tube body 201. A ball valve switch 407 and a permeable stone core 207 are installed between the sample tube and the pressure sensor 215. A three-way switch 410 is installed between the sample tube and the dynamic negative pressure generator 325, and a three-way switch 410 is installed between the annular water-gas separator 320 and the pressure stabilizing tube.

[0050] Several pressure sensors 215 are installed on both sides of the sample cylinder. A vacuum pressure gauge 312 and a negative pressure regulator 313 are installed between the pressure stabilizing cylinder and the vacuum pump 314. A dynamic negative pressure generator 325 is located between the sample cylinder and the pressure stabilizing cylinder 301. The volumetric flasks include a first volumetric flask 401, a second volumetric flask 402, and a third volumetric flask 403. Each of these flasks is equipped with a stopper 404. The three-way manifold includes an air extraction manifold 413 and a water passage manifold 419. A three-way switch 410 is installed between the air extraction manifold 413 and the stopper 404. The air extraction manifold 413 communicates with the pressure stabilizing cylinder 301. A ball valve 407 is installed between the air extraction manifold 413 and the pressure stabilizing cylinder. A ball valve 407 is installed between the water passage 419 and the stopper 404. The water passage 419 communicates with the annular water-gas separator 320.

[0051] A method for using a silt infiltration and infiltration deformation device based on a dynamic negative pressure working condition comprises the following steps:

[0052] a: Check the sealing of the instrument

[0053] 1) Close the ball valve switch 407 between the liftable water supply tank 101 and the sample tube base 230, block the exhaust hole on the sample tube base 230, and open the three-way switch 410 between the pressure stabilizing tube 301 and the sample tube cover 240;

[0054] 2) Remove the pressure sensors 215 on both sides of the sample tube body 201 and the negative pressure sensor 244 on the sample tube cover 240; close the ball valve switches 407 on the sample tube body 201 and the sample tube cover 240; open the ball valve switch 407 between one side of the sample tube body 201 and the annular water-gas separator 320, open the ball valve switch 407 between the pressure-stabilizing tube and the air extraction three-way pipe 413, close the three-way switch 410 channel between the pressure-stabilizing tube and the annular water-gas separator 320 that is connected to the atmosphere, open the ball valve switch 407 between the water three-way pipe 419 and the stoppers of the three volumetric flasks, and close the three-way switch 410 channel between the air extraction three-way pipe 413 and the stoppers of the three volumetric flasks that is connected to the atmosphere;

[0055] 3) Turn on the vacuum pump 314 to check the tightness of the sample tube. When the vacuum pressure gauge 312 reaches 1 atmospheric pressure, turn off the vacuum pump 314. If the reading of the vacuum pressure gauge 312 remains basically unchanged for 2 hours, the test device is considered to be leak-free.

[0056] b: Preparation of sample

[0057] 1) Remove the sample tube body 201 and open the ball valve switches 407 on both sides to put it in the exhaust state. Weigh a representative soil sample from the air-dried and loose soil sample. Calculate the sample dry mass based on the controlled dry density of the soil sample, the sample tube radius (r) and the sample control height (h). m d );

[0058] 2) After the sample is evenly loaded, compact it with a jack and measure the actual thickness of the sample (about 15cm~20cm);

[0059] c: Sample saturated with negative pressure

[0060] 1) Place a filter membrane on the metal perforated plate 235 of the sample tube base 230, and place the filter membrane, metal perforated plate 235, and hollow flower tube 236 on the top surface of the sample tube body 201 in sequence. Place the filter membrane on the metal perforated plate 235 of the sample tube base 230, close the sample tube cover 240, install and tighten the flanges between the base and the tube body, and between the tube body and the cover, and seal them with seals; connect the three-way switch 410 between the pressure-stabilizing tube 301 and the sample tube cover 240 and open it, close the sample tube cover 240 and the ball valve switch 407 on the side of the sample tube body 201, close the ball valve switch 407 between the pressure-stabilizing tube 301 and the exhaust three-way pipe 413, and close the three-way switch 410 between the pressure-stabilizing tube 301 and the annular water-gas separator 320;

[0061] 2) Adjust the water supply tank 101 so that the water level is slightly higher than the bottom surface of the sample tube base 230. Slowly open the ball valve switch 407 on the side of the sample tube base 230. After water flows out of the vent hole on the sample tube base 230, close the ball valve switch 407.

[0062] 3) Turn on the vacuum pump 314, adjust the negative pressure regulator 313 so that the vacuum pressure gauge 312 reaches a pressure value of 20 kPa, and continue to pump air for about 1 hour. Slightly open the ball valve switch 407 between the liftable water supply tank 101 and the sample tube base 230 to slowly inject a very thin stream of water into the sample tube. Continue to pump air and maintain the pressure value of the vacuum pressure gauge 312 unchanged until the water level in the sample tube overflows the metal orifice plate 235 on the sample surface layer. Then slowly raise the liftable water supply tank until its water level is slightly higher than the metal orifice plate 235 on the sample tube surface layer (the water level in the water supply tank is basically kept equal to the water level in the sample tube). During the water injection process, adjust the switch of the negative pressure regulator 313 to keep the value of the vacuum pressure gauge 312 basically unchanged, and then turn off the vacuum pump.

[0063] 4) Slowly open the three-way switch 410 on the sample tube cover 240 to connect it to the atmosphere, and open the negative pressure regulator 313 until the pressure on the vacuum pressure gauge 312 reaches zero, indicating that the sample is saturated;

[0064] d: Test method under dynamic negative pressure conditions

[0065] 1) Remove the metal orifice plate 235 and filter membrane on the top surface of the sample in the sample tube, replace them with a metal mesh sheet (diamond-shaped 10mm*5mm), place the hollow flower tube 236 on the metal mesh sheet, and then tighten the sample tube cover 240 (the connection part is fixed with a flange and sealed with a seal). Then, open the ball valve switches 407 on both sides of the sample tube in sequence from bottom to top, and install the pressure sensor 215 on the side of the sample tube body 201 underwater; install the negative pressure sensor 244 on the sample tube cover 240, turn on the camera 223 on the side of the sample tube body 201, and open the ball valve switch 407 between the sample tube cover 240 and the negative pressure sensor 244;

[0066] 2) Open the ball valve switch 407 between the sample tube body 201 and the annular water-gas separator 320, connect the annular water-gas separator 320 with the pressure-stabilizing tube 301, open the ball valve switch 407 between the pressure-stabilizing tube 301 and the air extraction three-way pipe 413, open the ball valve switches 407 between the three volumetric flask stoppers 404 and the water three-way pipe 419, and open the three-way switch 410 between the three volumetric flasks and the air extraction three-way pipe 413; start the vacuum pump 314 to evacuate the entire test device, adjust the negative pressure regulator 313 between the vacuum pump 314 and the vacuum pressure gauge 312, and when the negative pressure sensor 244 on the sample tube cover 240 and the vacuum pressure gauge 312 reach the required negative pressure value, continue to maintain the vacuum degree;

[0067] 3) Close the ball valve switch 407 between the second and third volumetric flasks 402 and 403 and the water three-way pipe 419, and slowly raise the liftable water supply tank 101 by 15-20 cm each time. After the water level in the liftable water supply tank 101 is equal to the water level in the sample tube and a 10-minute pause, raise the liftable water supply tank 101 again until water flows out of the overflow port 208 on one side of the tube body, maintaining a constant head difference to form the initial infiltration slope; and start the dynamic negative pressure generator;

[0068] 4) After the water flow rate stabilizes, close the ball valve 407 between the first volumetric flask 401 and the water three-way pipe 419. Simultaneously, open the ball valve 407 between the second volumetric flask 402 and the water three-way pipe 403. Start a stopwatch and measure the readings of the pressure sensors on both sides of the sample cylinder (i.e., the corresponding pressure head Hi at different seepage diameter L positions).

[0069] 5) Close the connection between the first volumetric flask 401 and the three-way exhaust pipe 413, and connect the first volumetric flask 401 to the atmosphere; remove the cap 404 of the first volumetric flask 401, pour out the water in the bottle, reinstall the first volumetric flask 401, close the three-way switch 410 on the first volumetric flask 401 that connects to the atmosphere, and connect the three-way exhaust pipe 413 to the first volumetric flask 401 for next use;

[0070] 6) After a certain amount of water is added to the second volumetric flask 402, close the ball valve between the second volumetric flask 402 and the water three-way pipe 419 and count the time (t). Simultaneously, open the ball valve 407 between the third volumetric flask 403 and the water three-way pipe 419 and count the time (t). Re-read the pressure sensors 215 on both sides of the sample cylinder (the sensor readings 215 should remain essentially unchanged).

[0071] 7) Close the connection between the second volumetric flask 402 and the three-way exhaust pipe 413, connect the second volumetric flask 402 to the atmosphere, remove the cap 404 of the second volumetric flask, weigh the amount of water in the second volumetric flask 402 and pour out all the water, reinstall the second volumetric flask 402, close the three-way switch 410 on the second volumetric flask 402 that connects to the atmosphere, and connect the three-way exhaust pipe 413 to the second volumetric flask 402 for future use;

[0072] 8) Thereafter, repeat steps 6) and 7), using the second volumetric flask 402 and the third volumetric flask 403 alternately;

[0073] 9) Each time the volumetric flask is filled with water, measure and record the changes in the water temperature, room temperature, and the value of the pressure sensor 215 on the side of the sample tube. Carefully observe various phenomena that occur during the test, such as the turbidity of the water, bubbles, fine particles carried out by the water flow, soil suspension, etc., and measure the turbidity of the seepage water;

[0074] 10) Read the water seepage volume three times in a row, with an interval of 20 to 30 minutes between each reading. When the measured pressure sensor 215 value, water seepage volume, and turbidity are basically stable, the water head can be increased to the next level. Each time the water head is increased, maintain it for 30 minutes to 1 hour. After observing that the reading pattern of the pressure sensors 215 on both sides of the sample tube is basically stable, repeat the test according to the above steps 4) to 9) (when approaching the critical slope drop, the water head increase should be reduced as appropriate) until the test is failed or when the water head can no longer be increased. The test can then be terminated.

[0075] e: Test method under normal seepage water pressure condition

[0076] Remove the negative pressure system and water-gas separation system. The remaining test steps are the same as those under dynamic negative pressure conditions.

[0077] f: Penetration damage judgment method

[0078] Observe the changes in soil suspension, combine with the turbidity measurement of seepage water, and make a comprehensive judgment on the changes in the slope of the relationship curve between seepage gradient and seepage velocity (lgi ~lgv).

[0079] Final calculations and graphing:

[0080] 1) The calculation formula for the dry density of the sample is:

[0081] in, m d —Dry mass of sample, g;

[0082] r — sample radius, cm;

[0083] h —actual height of the sample, cm;

[0084] ρ d —Dry density, g / cm 3 ;

[0085] 2) The calculation formulas for permeability gradient, permeability velocity and permeability coefficient are as follows:

[0086]

[0087]

[0088] in, i —Infiltration gradient;

[0089] △H—pressure tube head difference (i.e. H1-H2), cm (H1, H2, when the sensor pressure is positive, take "+", when negative, take "-");

[0090] L —seepage path length corresponding to the head difference △H, cm;

[0091] Q — water seepage, cm 3 ;

[0092] t —time, s;

[0093] A — sample area, cm 2 , (the sample area can be calculated based on the sample radius r);

[0094] υ —seepage velocity, cm / s;

[0095] k T —Permeability coefficient, cm / s;

[0096] 3) Identification of seepage deformation and damage: Draw the relationship curve between seepage slope and seepage velocity on double logarithmic paper (seepage velocity v is the horizontal axis, the infiltration slope i is the vertical axis);

[0097] like Figure 2 As shown, when lg i ~lg v The slope of the relationship curve begins to change, and small cracks or fine particles are observed in the soil or carried out by the water flow. When the turbidity reaches 300-500, it is considered that the sample has reached the critical slope. i k , the value is:

[0098]

[0099] In the formula i 2 – slope when piping begins to occur;

[0100] i 1 – The slope before piping begins to appear.

[0101] As the water head gradually increases, fine particles are continuously washed away and the infiltration flow rate increases. When the water head increases to the point where the sample loses its anti-seepage strength and the turbidity is greater than about 500-800, the slope is the failure slope of the sample. i F , whose values ​​are:

[0102]

[0103] In the formula i '2—seepage slope at specimen failure;

[0104] i '1—The seepage gradient before the specimen is destroyed.

[0105] When soil failure occurs, sometimesi '2, if it is not easy to measure, it can be calculated as follows:

[0106] i F = i '1

[0107] In summary, the silt infiltration and infiltration deformation device and method based on dynamic negative pressure working conditions provided by the present invention can be used for equipment system sealing inspection, and can also be combined with normal seepage water pressure to truly simulate the infiltration force under the action of waves and tides; at the same time, by alternating the use of the second volumetric flask 402 and the third volumetric flask 403, water vapor separation and seepage water collection under long-term continuous test working conditions can be achieved; it can also monitor in real time the changing process of infiltration deformation such as piping deformation of silt surface particles or flow deformation or combined deformation of piping and flow deformation under different water heads, so as to more scientifically and reasonably determine the critical slope, destruction slope and other control indicators of silt infiltration deformation, which is beneficial to ensuring the safety and stability of anti-seepage of silt embankment projects.

[0108] The above content is a further detailed description of the technical solution provided in combination with the preferred implementation methods of this patent. It cannot be determined that the specific implementation of the present invention is limited to the above descriptions. For ordinary technicians in the technical field to which this patent belongs, they can make several simple deductions or replacements without departing from the concept of this patent, which should be deemed to fall within the scope of protection of this patent.

Claims

1. A silt infiltration and infiltration deformation device based on dynamic negative pressure working conditions, characterized by: It includes a liftable water supply tank, a sample cylinder, a pressure stabilizing cylinder and a vacuum pump connected in sequence. A negative pressure system, a water-gas separation system and a measurement system are provided between the sample cylinder, the pressure stabilizing cylinder and the vacuum pump or on the device. The negative pressure system includes a negative pressure sensor, a dynamic negative pressure generator and a negative pressure regulator. The water-gas separation system includes an annular water-gas separator and a three-way pipe; The measuring system includes a pressure sensor, a volumetric flask and a vacuum pressure gauge; The three-way pipe is respectively connected to the volumetric flask, the annular water-gas separator and the pressure-stabilizing cylinder, and the annular water-gas separator is respectively connected to the sample cylinder, the three-way pipe and the pressure-stabilizing cylinder; The sample tube includes a sample tube base, a sample tube body and a sample tube cover. A metal orifice plate is provided between the sample tube base and the sample tube body. A metal orifice plate is provided inside the sample tube body. A hollow flower tube is provided between the metal orifice plate on the top surface of the sample in the sample tube and the sample tube cover. The liftable water supply box is in communication with the sample tube base, and a ball valve switch is provided between the liftable water supply box and the sample tube base. The volumetric flask includes a first volumetric flask, a second volumetric flask and a third volumetric flask. The openings of the first volumetric flask, the second volumetric flask and the third volumetric flask are all provided with bottle stoppers. The three-way pipe includes an air extraction three-way pipe and a water flow three-way pipe. A three-way switch is provided between the air extraction three-way pipe and the bottle stoppers, and the air extraction three-way pipe is connected to a pressure stabilizing cylinder. A ball valve switch is provided between the air extraction three-way pipe and the pressure stabilizing cylinder.

2. The device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions according to claim 1, characterized in that: The negative pressure sensor is arranged on the cover of the sample tube, and a ball valve switch is arranged between the negative pressure sensor and the cover of the sample tube.

3. The device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions according to claim 2, characterized in that: A scale and a camera are provided on one side of the sample tube body.

4. The device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions according to claim 3, characterized in that: A ball valve switch and a permeable stone core are provided between the sample tube and the pressure sensor.

5. The device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions according to claim 4, characterized in that: A three-way switch is provided between the sample cylinder and the dynamic negative pressure generator, and a three-way switch is provided between the annular water-gas separator and the pressure stabilizing cylinder.

6. The device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions according to claim 5, characterized in that: A plurality of pressure sensors are provided on both sides of the sample cylinder, the dynamic negative pressure generator is provided between the sample cylinder and the pressure stabilizing cylinder, and the vacuum pressure gauge and the negative pressure regulator are provided between the pressure stabilizing cylinder and the vacuum pump.

7. The device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions according to claim 6, characterized in that: A ball valve switch is provided between the water-passing three-way pipe and the bottle stopper, and the water-passing three-way pipe is communicated with the annular water-gas separator.

8. A method for using the device for silt infiltration and infiltration deformation based on dynamic negative pressure working conditions as claimed in claim 7, characterized in that , including the following steps: a: Check the sealing of the instrument b: Preparation of sample c: Sample saturated with negative pressure 1) Place the filter membrane, metal orifice plate, and hollow flower tube on the top of the sample cylinder in sequence. Place the filter membrane on the metal orifice plate at the base of the sample cylinder. Install and tighten the flanges between the base and the cylinder, and between the cylinder and the cylinder cover, and seal them with seals. Connect the three-way switch between the pressure-stabilizing cylinder and the sample cylinder cover and open it. Close the ball valve switch on the sample cylinder cover and the side of the sample cylinder. Close the ball valve switch between the pressure-stabilizing cylinder and the three-way switch between the pressure-stabilizing cylinder and the exhaust three-way pipe, and close the three-way switch between the pressure-stabilizing cylinder and the annular water-gas separator. 2) Adjust the water supply tank so that the water level is slightly higher than the bottom surface of the sample tube base. Slowly open the ball valve switch on the side of the sample tube base. After water flows out of the exhaust hole on the sample tube base, close the ball valve switch. 3) Turn on the vacuum pump and adjust the negative pressure regulator to make the vacuum pressure gauge reach a pressure value of 20KPa. Continue to pump air for 1 hour. Slightly open the ball valve switch on the base of the sample tube to allow a very thin stream of water to slowly flow into the sample tube. Continue to pump air and maintain the pressure value on the vacuum pressure gauge unchanged until the water level in the sample tube overflows the metal orifice plate on the surface of the sample. Then slowly raise the liftable water supply tank until its water level is slightly higher than the water level of the metal orifice plate on the surface of the sample tube. Turn off the vacuum pump. 4) Slowly open the three-way switch on the cover of the sample tube to connect it to the atmosphere, and open the negative pressure regulator until the pressure on the vacuum pressure gauge reaches zero, indicating that the sample is saturated; d: Test method under dynamic negative pressure conditions 1) Remove the metal orifice plate and filter membrane on the top surface of the sample in the sample tube, replace them with a metal mesh sheet, then open the ball valves on both sides of the sample tube in sequence from bottom to top, and install the pressure sensor on the side of the sample tube underwater; Turn on the camera on one side of the sample tube body and open the ball valve switch between the sample tube cover and the negative pressure sensor; 2) Open the ball valve between the sample tube and the annular water-gas separator, connect the annular water-gas separator and the pressure-stabilizing tube, open the ball valve between the pressure-stabilizing tube and the three-way exhaust pipe, open the ball valves between the stoppers of the three volumetric flasks and the three-way water pipe, and open the three-way switch between the three volumetric flasks and the three-way exhaust pipe; start the vacuum pump to evacuate the entire test device, adjust the negative pressure regulator between the vacuum pump and the vacuum pressure gauge, and when the negative pressure sensor on the sample tube cover and the vacuum pressure gauge reach the required negative pressure value, continue to maintain the vacuum degree; 3) Close the ball valves between the second and third volumetric flasks and the water three-way pipe, and slowly raise the liftable water supply tank by 15-20 cm each time. After the water level in the liftable water supply tank is equal to the water level in the sample tube and wait for 10 minutes, raise the liftable water supply tank again until water flows out of the overflow port on one side of the tube body, maintaining a constant head difference to form the initial infiltration slope; turn on the dynamic negative pressure generator; 4) After the water flow rate stabilizes, close the ball valve between the first volumetric flask and the water three-way pipe. At the same time, open the ball valve between the second volumetric flask and the water three-way pipe. Start the stopwatch and read the pressure sensors on both sides of the sample cylinder. 5) Close the connection between the first volumetric flask and the three-way exhaust pipe, and connect the first volumetric flask to the atmosphere; pull out the cap of the first volumetric flask, pour out the water in the bottle, reinstall the first volumetric flask, close the three-way switch channel on the first volumetric flask that connects to the atmosphere, and connect the three-way exhaust pipe to the first volumetric flask for next use; 6) When the second volumetric flask receives a certain amount of water, close the ball valve between the second volumetric flask and the water three-way pipe and start counting the seconds. At the same time, open the ball valve between the third volumetric flask and the water three-way pipe and start counting the seconds. Again, read the pressure sensor readings on both sides of the sample cylinder. 7) Close the connection between the second volumetric flask and the three-way exhaust pipe, connect the second volumetric flask to the atmosphere, remove the cap of the second volumetric flask, weigh the amount of water in the second volumetric flask and pour out all the water in the flask, reinstall the second volumetric flask, close the three-way switch channel on the second volumetric flask that connects to the atmosphere, and connect the three-way exhaust pipe to the second volumetric flask for next use; 8) Repeat steps 6) and 7) using the second and third volumetric flasks alternately; 9) Each time the volumetric flask is filled with water, measure and record the changes in water temperature, room temperature, and the value of the pressure sensor on the side of the sample tube, and weigh and measure the turbidity of the seeping water; 10) Read the water seepage volume several times continuously. When the pressure sensor value, water seepage volume, and turbidity are basically stable, you can move on to the next level of water head. After increasing the water head and observing that the pressure sensor readings on both sides of the sample tube are basically stable, repeat the test according to the above steps 4) to 9) until the test fails or the water head can no longer be increased. The test can then be terminated. e: Test method under normal seepage water pressure condition Remove the negative pressure system and water-gas separation system. The remaining test steps are the same as those under dynamic negative pressure conditions. f: Penetration damage judgment method Observe the changes in soil suspension, combine with the turbidity measurement of seepage water, and make a comprehensive judgment on the changes in the slope of the curve of the relationship between seepage gradient and seepage velocity.

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