Testing device capable of monitoring rock and soil sample damage under salt-dry-wet cycle composite action

Abstract

The invention discloses a test device capable of monitoring rock-soil sample damage under salt-dry-wet cycle composite action, the device comprises an erosion bin, a drying bin and a connection bin, the drying bin is located above the erosion bin, the connection bin is located at the connection position of the erosion bin and the drying bin, the bottom of the erosion bin is fixedly connected with a support frame, and the support frame is fixedly connected with the bottom of the drying bin. The bottom of the erosion bin communicates with a first annular pipe, the top of the drying bin communicates with a second annular pipe, the end of the first annular pipe is connected with a first air compressor, and the position, close to one side, of the top of the second annular pipe is connected with a second air compressor. The test device capable of monitoring the damage of the rock-soil sample under the salt-dry-wet cycle composite action can accurately control the concentration and the drying degree of a salt solution, can effectively reduce the influence of salt crystals in the sample on the damage degree and the mass loss rate determination, and has the advantages of high detection efficiency and accurate monitoring result.

Description

[0001] The present invention belongs to the technology of testing the durability performance of geotechnical materials, and particularly relates to a test device capable of monitoring the damage of geotechnical specimens under the combined action of salt-wet-dry cycles. Background Art

[0003] Currently, the experimental research on the salt-wet-dry cycle durability of geotechnical materials mainly adopts the method of artificially preparing salt solutions combined with oven drying. This experimental scheme includes two key control links: during the salt erosion stage, it is necessary to maintain a constant solution concentration and ensure that the specimens are completely saturated; during the drying stage, it is required to accurately regulate the moisture content of the specimens to the target value.

[0004] However, the traditional experimental method has significant technical defects: firstly, limited by equipment conditions, it is difficult to maintain the stability of the salt solution concentration during the test process, and there is uneven dehydration of the specimens from top to bottom during the drying process, resulting in inaccurate determination of the drying degree; secondly, the conversion between the erosion-drying process depends on manual operation, resulting in large discreteness of experimental results and low efficiency. In addition, the residual salt crystals in the specimens will occupy a certain volume, and conventional nuclear magnetic resonance technology cannot effectively distinguish salt crystals from the geotechnical matrix, resulting in errors in porosity measurement and affecting the evaluation accuracy of wet-dry-salt erosion damage degree; at the same time, the presence of residual salt crystals will also interfere with the accurate calculation of the mass loss rate.

[0005] Therefore, in view of the above problems, this case proposes a test device capable of monitoring the damage of geotechnical specimens under the combined action of salt-wet-dry cycles. Summary of the Invention

[0006] The main purpose of the present invention is to provide a test device capable of monitoring the damage of geotechnical specimens under the combined action of salt-wet-dry cycles, which can effectively solve the technical problems in the background art.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is:

[0008] A test device capable of monitoring the damage of geotechnical specimens under the combined action of salt-wet-dry cycles, including an erosion chamber, a drying chamber, and a connection chamber. The drying chamber is located above the erosion chamber, the connection chamber is located at the connection between the erosion chamber and the drying chamber. A support frame is fixedly connected to the bottom of the erosion chamber. A first annular pipe is communicated with the bottom of the erosion chamber. A second annular pipe is communicated with the top of the drying chamber. A first air compressor is connected to the end of the first annular pipe. A second air compressor is connected to a position near one side of the top of the second annular pipe, and an air extraction box is connected to a position near the other side of the top of the second annular pipe. A third air compressor and a fourth air compressor are arranged outside the connection chamber, and the third air compressor and the fourth air compressor pass through the connection chamber and are communicated with the drying chamber. Heaters are evenly distributed on the outside of the drying chamber. A damage monitor is fixedly installed at the front of the support frame.

[0009] As a further solution of the present invention, the heater is distributed at the top, middle and bottom positions of the outer side of the drying chamber, and an air inlet pipe is connected between the heater and the drying chamber, an exhaust pipe is connected to the outer surface of the drying chamber, and a temperature and wind speed controller is connected to the middle position of the air inlet pipe.

[0010] As a further solution of the present invention, the air inlet pipe and the air outlet pipe are arranged alternately to form a twisted wind direction for drying while driving the sample to rotate and dry moisture.

[0011] As a further solution of the present invention, a salt solution configuration box and a kerosene storage box are arranged outside the erosion bin, and a salt solution collection box and a kerosene collection box are symmetrically arranged outside the erosion bin.

[0012] As a further solution of the present invention, a delivery pipe is connected between the salt solution configuration box and the erosion chamber, and a booster is connected to the middle position of the delivery pipe.

[0013] As a further solution of the present invention, a No. 1 electronic scale is provided at the bottom of the erosion chamber, and a placement rack is fixedly connected to the inner side of the erosion chamber, a fragment collector is fixedly connected to the upper surface of the placement rack, and a sample saturation monitor and a salt solution concentration sensor are embedded in the interior of the erosion chamber.

[0014] As a further solution of the present invention, a filter screen is arranged at the top of the fragment collector near the edge, and a No. 2 electronic scale is embedded in the groove of the fragment collector. A heating wire is fixedly installed inside the fragment collector.

[0015] As a further solution of the present invention, a test block protection layer is bonded to the inner surface of the drying chamber, and an infrared moisture monitor and a temperature sensor are arranged inside the drying chamber.

[0016] As a further solution of the present invention, a sliding switch is fixedly connected to the outer side of the connecting bin, and a No. 3 electronic scale is arranged inside the connecting bin, and a driving rod is connected between the No. 3 electronic scale and the sliding switch.

[0017] As a further solution of the present invention, a guide frame is symmetrically arranged on the inner side of the connecting bin, a guide block is connected between the No. 3 electronic scale and the guide frame, and the No. 3 electronic scale is slidably connected to the guide frame through the guide block.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. Use high-precision sensors to monitor and maintain the concentration of salt solution in real time to ensure that the sample is in a constant salt solution environment during the erosion stage; at the same time, combine gradient temperature control and reverse wind direction drying technology to effectively reduce the uneven dehydration phenomenon during the sample drying process, achieve precise control of the drying degree and improve drying efficiency.

[0020] 2. Through the damage monitoring system, the quality change of the geotechnical sample under the combined action of salt-wet-dry cycles is monitored in real time, the interference of residual salt crystals on the measurement of the porosity and mass loss rate of the sample is reduced, and the accuracy of the damage degree and mass loss rate is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of an experimental device for monitoring the damage of geotechnical samples under the combined action of salt-wet-dry cycles according to the present invention;

[0022] Figure 2 It is a schematic diagram of the internal structure of the erosion chamber of an experimental device for monitoring the damage of geotechnical samples under the combined action of salt-wet-dry cycles according to the present invention;

[0023] Figure 3 It is a schematic diagram of the internal structure of the drying chamber of an experimental device for monitoring the damage of geotechnical samples under the combined action of salt-wet-dry cycles according to the present invention;

[0024] Figure 4 It is a schematic diagram of the structure of the debris collector of an experimental device for monitoring the damage of geotechnical samples under the combined action of salt-wet-dry cycles according to the present invention;

[0025] Figure 5 It is a schematic diagram of the internal structure of the connection chamber of an experimental device for monitoring the damage of geotechnical samples under the combined action of salt-wet-dry cycles according to the present invention;

[0026] Figure 6 It is a sectional analysis diagram of the drying chamber of an experimental device for monitoring the damage of geotechnical samples under the combined action of salt-wet-dry cycles according to the present invention.

[0027] In the figure: 1. Erosion chamber; 2. Drying chamber; 3. Connection chamber; 4. Support frame; 5. First annular pipe; 6. Second annular pipe; 7. First air compressor; 8. Second air compressor; 9. Air extraction box; 10. Third air compressor; 11. Fourth air compressor; 12. Heater; 13. Intake pipe; 14. Exhaust pipe; 15. Temperature and wind speed controller; 16. Salt solution preparation tank; 17. Kerosene storage tank; 18. Booster; 19. Salt solution collection tank; 20. Kerosene collection tank; 21. First electronic scale; 22. Placing rack; 23. Debris collector; 24. Sample saturation monitor; 25. Salt solution concentration sensor; 26. Specimen protective layer; 27. Infrared moisture monitor; 28. Temperature sensor; 29. Filter screen; 30. Second electronic scale; 31. Heating wire; 32. Slide switch; 33. Third electronic scale; 34. Driving rod; 35. Guide frame; 36. Guide block; 37. Damage monitor. DETAILED DESCRIPTION OF THE INVENTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0029] like Figures 1-6 As shown, a test device capable of monitoring the damage of rock and soil samples under the combined action of salt-wet-dry cycle comprises an erosion chamber 1, a drying chamber 2 and a connecting chamber 3, the drying chamber 2 is located above the erosion chamber 1, the connecting chamber 3 is located at the connection between the erosion chamber 1 and the drying chamber 2, a support frame 4 is fixedly connected to the bottom of the erosion chamber 1, a No. 1 annular pipe 5 is connected to the bottom of the erosion chamber 1, a No. 2 annular pipe 6 is connected to the top of the drying chamber 2, an No. 1 air compressor 7 is connected to the end position of the No. 1 annular pipe 5, a No. 2 air compressor 8 is connected to the top of the No. 2 annular pipe 6 near one side, and an exhaust box 9 is connected to the top of the No. 2 annular pipe 6 near the other side, a No. 3 air compressor 10 and a No. 4 air compressor 11 are arranged on the outside of the connecting chamber 3, the No. 3 air compressor 10 and the No. 4 air compressor 11 pass through the connecting chamber 3 and are connected to the drying chamber 2, a heater 12 is evenly distributed on the outside of the drying chamber 2, and a damage monitor 37 is fixedly installed on the front of the support frame 4.

[0030] In this embodiment, the heater 12 is distributed at the top, middle and bottom positions of the outer side of the drying chamber 2, and an air inlet pipe 13 is connected between the heater 12 and the drying chamber 2, an exhaust pipe 14 is connected to the outer surface of the drying chamber 2, and a temperature and wind speed controller 15 is connected to the middle position of the air inlet pipe 13.

[0031] The heaters 12 at the top, middle and bottom divide the drying chamber 2 into three layers, which are separated by partitions and buffer pipes are arranged inside the partitions to prevent the samples from colliding with the partitions and being damaged during the rotary drying process. The drying temperatures of the three layers are set to 40°C, 45°C and 50°C respectively to solve the problem that the bottom of the sample dries slowly and the upper part dries quickly.

[0032] In this embodiment, the air inlet pipe 13 and the air outlet pipe 14 are arranged alternately to form a twisted wind direction for drying while driving the sample to rotate and dry moisture.

[0033] The drying efficiency of the sample in the drying chamber 2 can be improved.

[0034] In this embodiment, a salt solution configuration box 16 and a kerosene storage box 17 are disposed outside the erosion chamber 1 , and a salt solution collection box 19 and a kerosene collection box 20 are symmetrically disposed outside the erosion chamber 1 .

[0035] The salt solution configuration box 16 conveys the salt solution into the erosion chamber 1, the salt solution collection box 19 recovers the eroded salt solution, the kerosene storage box 17 conveys kerosene into the erosion chamber 1, and the kerosene collection box 20 recovers the kerosene.

[0036] In this embodiment, a delivery pipe is connected between the salt solution preparation tank 16 and the erosion chamber 1, and a booster 18 is connected to the middle position of the delivery pipe.

[0037] The booster 18 can boost the delivery pipe between the salt solution preparation tank 16 and the erosion chamber 1.

[0038] In this embodiment, a first electronic scale 21 is provided at the bottom of the erosion chamber 1, and a placement rack 22 is fixedly connected to the inner side of the erosion chamber 1. A debris collector 23 is fixedly connected to the upper surface of the placement rack 22. A specimen saturation monitor 24 and a salt solution concentration sensor 25 are embedded in the erosion chamber 1.

[0039] The specimen saturation monitor 24 and the salt solution concentration sensor 25 monitor the salt concentration of each layer in the erosion chamber 1 to ensure that the salt solution concentration is constant during the erosion process and avoid incomplete erosion caused by a decrease in concentration.

[0040] In this embodiment, a filter screen 29 is provided at the top of the debris collector 23 near the edge, and a second electronic scale 30 is embedded in the groove of the debris collector 23. A heating wire 31 is fixedly installed inside the debris collector 23.

[0041] The heating wire 31 inside the debris collector 23 dries the specimen, and the second electronic scale 30 weighs the specimen.

[0042] In this embodiment, a specimen protective layer 26 is bonded to the inner surface of the drying chamber 2, and an infrared moisture monitor 27 and a temperature sensor 28 are provided inside the drying chamber 2.

[0043] The specimen protective layer 26 can protect the rotating specimen. The temperature sensor 28 ensures constant temperature drying. The infrared moisture monitor 27 monitors the moisture content of the specimen to ensure uniform drying of the three layers and consistent drying coefficients.

[0044] In this embodiment, a sliding switch 32 is fixedly connected to the outside of the connection chamber 3, and a third electronic scale 33 is provided inside the connection chamber 3. A driving rod 34 is connected between the third electronic scale 33 and the sliding switch 32. Guide frames 35 are symmetrically provided inside the connection chamber 3. A guide block 36 is connected between the third electronic scale 33 and the guide frames 35, and the third electronic scale 33 is slidably connected to the guide frames 35 through the guide block 36.

[0045] When the sliding switch 32 is started, the driving rod 34 drives the third electronic scale 33. The third electronic scale 33 slides through the guide block 36 and the guide frames 35, which can drive the third electronic scale 33 to move.

[0046] It should be noted that the present invention is a test device for monitoring the damage of rock and soil under the combined action of salt-wet and dry cycles, and the operation process is as follows:

[0047] Step 1: Place the specimen into the erosion chamber 1. Through the combined action of the first air compressor 7 and the air extraction box 9, transfer the specimen to the drying chamber 2. The second air compressor 8, the third air compressor 10, and the fourth air compressor 11 cooperate to suspend the specimen in the drying chamber 2. The heater 12 and the temperature and wind speed controller 15 dry the specimen in two ways: layer-by-layer drying and centrifugal force to throw out moisture. The infrared moisture monitor 27 for each layer detects the drying degree of the specimen. When the specimen is fully dried, turn off the second air compressor 8, the third air compressor 10, the fourth air compressor 11, and the heater 12, so that the specimen lands steadily on the third electronic scale 33, and use the third electronic scale 33 to measure the mass m of the dried specimen. d , then the air extraction box 9, the third air compressor 10, and the fourth air compressor 11 cooperate to suspend the specimen. Turn on the sliding switch 32, turn off the air extraction box 9 and the third air compressor 10, and start the first air compressor 7 and the second air compressor 8 to make the specimen return to the erosion chamber 1. Inject the salt solution into the erosion chamber 1, use the specimen saturation monitor 24 to ensure that the specimen is fully saturated, and after discharging the excess solution, the first electronic scale 21 weighs the mass m of the saturated specimen. s , and transmit the data to the damage monitor 37.

[0048] Step 2: Inject the salt solution and conduct layer-by-layer salt erosion on the specimen. At the same time, equip a salt solution concentration sensor 25 to detect the concentration of the solution. After 12 hours of erosion, open the solution discharge port switch to transport the solution to the salt solution collection box 19. After the salt solution is emptied, open the sliding switch 32. The first air compressor 7 and the second air compressor 8 are started and the exhaust hole switch is closed, and the specimen is transported to the drying chamber 2. Close the sliding switch 32. At the same time, the second air compressor 8, the third air compressor 10, and the fourth air compressor 11 are started to suspend the specimen in the drying chamber 2. Open the exhaust pipe 14 switch and start the heater 12 to fully dry the specimen for 12 hours. Close the exhaust pipe 14 switch, the third air compressor 10, and the fourth air compressor 11, open the sliding switch 32 and start the first air compressor 7 to transport the specimen to the erosion chamber 1. After reaching the position, close the first air compressor 7 and the sliding switch 32.

[0049] Step 3: Repeat Step 2 until after the last wet-dry cycle. Through the combined action of the first air compressor 7 and the air extraction box 9, the specimen is transferred to the drying chamber 2. The second air compressor 8, the third air compressor 10, and the fourth air compressor 11 cooperate to suspend the specimen in the drying chamber 2. The heater 12 and the temperature and wind speed controller 15 dry the specimen in two ways: layer-by-layer drying and centrifugal force to throw out moisture. The drying degree of the specimen is detected by each layer of infrared moisture monitor 27. When the specimen is fully dried, turn off the second air compressor 8, the third air compressor 10, the fourth air compressor 11, and the heater 12, so that the specimen lands steadily on the third electronic scale 33, and use the third electronic scale 33 to measure the mass m′ of the dried specimen. d1 , the internal heating wire 31 of the debris collector 23 dries the specimen, and the second electronic scale 30 measures the dry mass of the debris as m′. d2 , subsequently, the air extraction box 9, the third air compressor 10, and the fourth air compressor 11 cooperate to suspend the specimen. Turn on the sliding switch 32, turn off the air extraction box 9, the third air compressor 10, and the fourth air compressor 11, start the first air compressor 7 and the second air compressor 8, so that the specimen returns to the erosion chamber 1. Inject kerosene into the erosion chamber 1, use the specimen saturation monitor 24 to ensure that the specimen is fully saturated, and after draining the kerosene, the first electronic scale 21 weighs the mass m of the saturated specimen s ′, and transmit the data to the damage monitor 37. Complete the wet-dry cycle.

[0050] Calculation method for pore damage degree and mass loss rate of specimen under wet-dry-salt erosion coupling action:

[0051] Mass m of the dried specimen d , mass m of the saturated specimen s , salt solution concentration is ρ salt , from which the mass m of the salt solution in the saturated specimen is calculated l , and the initial porosity of the specimen is calculated

[0052] After n times of wet-dry-salt erosion coupling action, the third electronic scale 33 measures the dry mass m′ of the specimen after n times of erosion d1 , the mass of the debris on the debris collector 23 is m′ d2 , the total mass of the specimen after n times of erosion is m′ d = m′ d1 + m′ d2 , calculate the mass m of the salt crystals inside the specimen salt = m′ d - m d and its corresponding volume

[0053] Known kerosene density is ρ m, the mass m of the kerosene-saturated specimen is measured by the first electronic scale 21 s ′, and the mass m l ′ of kerosene in the specimen is calculated, and the true pore volume inside the specimen is calculated Finally, the porosity of the specimen after n erosions is calculated

[0054] The monitoring system calculates the pore damage degree of the cement-soil specimen under the nth salt-wetting and drying cycle composite action and the mass loss rate is

[0055] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. An experimental device for monitoring the damage of geotechnical specimens under the combined action of salt-wet and dry cycles, characterized in that: It includes an erosion bin (1), a drying bin (2) and a connecting bin (3). The drying bin (2) is located above the erosion bin (1), and the connecting bin (3) is located at the connection between the erosion bin (1) and the drying bin (2). A support frame (4) is fixedly connected to the bottom of the erosion bin (1). A first annular pipe (5) is connected to the bottom of the erosion bin (1). A second annular pipe (6) is connected to the top of the drying bin (2). A first air compressor (7) is connected to the end of the first annular pipe (5). A second air compressor (8) is connected to a position near one side at the top of the second annular pipe (6), and an air extraction box (9) is connected to a position near the other side at the top of the second annular pipe (6). A third air compressor (10) and a fourth air compressor (11) are arranged on the outer side of the connecting bin (3), and the third air compressor (10) and the fourth air compressor (11) pass through the connecting bin (3) and are connected to the drying bin (2). Heaters (12) are evenly distributed on the outer side of the drying bin (2). A damage monitor (37) is fixedly installed at the front part of the support frame (4).

2. The test device for monitoring the damage of geotechnical specimens under the combined action of salt-wet and dry cycles according to claim 1, characterized in that: The heaters (12) are distributed at the top, middle and bottom positions on the outer side of the drying bin (2), and an intake pipe (13) is connected between the heaters (12) and the drying bin (2). An exhaust pipe (14) is connected to the outer surface of the drying bin (2). A temperature and wind speed controller (15) is connected to the middle position of the intake pipe (13).

3. The test device for monitoring the damage of geotechnical specimens under the combined action of salt-dry and wet cycles according to claim 2, characterized in that: The intake pipe (13) and the exhaust pipe (14) are arranged in an interleaved manner to form a twisted air flow for air drying while driving the specimen to rotate and spin-dry the moisture.

4. The test device for monitoring the damage of geotechnical specimens under the combined action of salt-wet and dry cycles according to claim 1, characterized in that: A salt solution preparation tank (16) and a kerosene storage tank (17) are arranged on the outer side of the erosion bin (1), and a salt solution collection tank (19) and a kerosene collection tank (20) are symmetrically arranged on the outer side of the erosion bin (1).

5. The test device for monitoring the damage of geotechnical specimens under the combined action of salt-wet and dry cycles according to claim 4, characterized in that: A delivery pipe is connected between the salt solution preparation tank (16) and the erosion bin (1), and a booster (18) is connected to the middle position of the delivery pipe.

6. The test device for monitoring the damage of geotechnical specimens under the combined action of salt-wet and dry cycles according to claim 1, characterized in that: A first electronic scale (21) is arranged at the bottom of the erosion bin (1), and a placement rack (22) is fixedly connected to the inner side of the erosion bin (1). A debris collector (23) is fixedly connected to the upper surface of the placement rack (22). A specimen saturation monitor (24) and a salt solution concentration sensor (25) are embedded in the erosion bin (1).

7. An experimental device for monitoring the damage of geotechnical specimens under the combined action of salt-wet and dry cycles according to claim 6, characterized in that: A filter screen (29) is arranged at a position near the edge at the top of the debris collector (23), and a second electronic scale (30) is embedded in the groove of the debris collector (23). A heating wire (31) is fixedly installed inside the debris collector (23).

8. An experimental device for monitoring the damage of rock and soil under the combined action of salt-dry and wet cycles according to claim 1, characterized in that: A specimen protection layer (26) is adhered to the inner surface of the drying bin (2), and an infrared moisture monitor (27) and a temperature sensor (28) are arranged inside the drying bin (2).

9. The test device for monitoring the damage of geotechnical specimens under the combined action of salt-wet and dry cycles according to claim 1, wherein: A sliding switch (32) is fixedly connected to the outer side of the connecting bin (3), and a third electronic scale (33) is arranged inside the connecting bin (3). A driving rod (34) is connected between the third electronic scale (33) and the sliding switch (32).

10. An experimental device for monitoring the damage of geotechnical specimens under the combined action of salt-dry and wet cycles according to claim 9, characterized in that: Guide frames (35) are symmetrically arranged inside the connection bin (3). A guide block (36) is connected between the third electronic scale (33) and the guide frame (35), and the third electronic scale (33) is slidably connected to the guide frame (35) through the guide block (36).

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