A portable in-situ frost heave and collapse detection device for saline soil

Abstract

The invention discloses a portable on-site in-situ frost heave and dissolution detection device for saline soil. A soil sample to be tested is located in a double-layer sample barrel. A sample barrel cover is arranged at the top opening of the double-layer sample barrel. A positioning rod is arranged on the top of a load transmission column. The lower end of the load transmission column passes through the sample barrel cover and is placed on a non-slip pad. A water sprinkling plate is fixed on the inner side of the sample barrel cover, and the water sprinkling plate faces the soil sample to be tested. An annular water belt is arranged on the inner wall of the double-layer sample barrel. A plurality of columnar composite sensors are buried in the annular direction in the soil sample to be tested. A laser rangefinder for detecting the distance between the sample barrel cover and the soil sample to be tested is arranged on the inner side of the sample barrel cover. The output end of the laser rangefinder is connected to a laser rangefinder signal processing system through a laser rangefinder signal transmission line. The device can study the influence of water content, salt and temperature of saline soil on frost heave and dissolution under the original condition of a natural saline soil sample, as well as the migration law of water and salt.

Description

Technical Field

[0001] The invention belongs to the technical field of engineering frozen soil, and relates to a portable on-site in-situ frost heave and dissolution detection device for saline soil. Background Art

[0002] Many infrastructure projects have encountered saline soil layers and roadbeds during their construction, such as the Qinghai-Tibet Railway, Lanzhou-Xinjiang Railway, Hami-Lop Nur Railway, and a large number of thermal power stations and wind power facilities built in Qinghai and Xinjiang. Therefore, in-depth research on the formation mechanism and changing laws of saline soil has become an important topic in the current research on saline soil.

[0003] Saline soil is a special regional soil. Northwest China is the most widely distributed area of ​​saline soil in my country. The large temperature difference between morning and evening and the special environment such as seasonal temperature difference in this area cause the salt in the saline soil to migrate, condense, freeze and thaw, thus affecting the bearing capacity of the saline soil foundation and causing great harm to buildings. The engineering properties of saline soil are not only related to factors such as water content, salt content and soil density, but also more affected by comprehensive environmental factors. Therefore, it is necessary to conduct freeze-thaw cycle and dissolution test research on saline soil in natural environment and comprehensively analyze the mechanism of saline soil. At present, the main method for scholars to study saline soil is to prepare samples after adding a certain amount of salt to the soil, study the mechanical properties of the soil after adding salt, and put the samples into a refrigerator for freeze-thaw cycles to simulate the temperature changes in the natural environment, or use reshaped saline soil for indoor tests. After the test is completed, the change law of the mechanical related parameters of the samples is studied, such as CN103743771 A, CN 107132128 A, CN 106501489 A, CN 203148930 U, etc. The main disadvantage of these methods is that it is difficult to truly study the real state of saline soil in the natural environment. Although CN 108333329 A proposes a test device for on-site determination of salt swelling of sulfate saline soil, it has a single purpose and a simple structure, and it is difficult to comprehensively and accurately measure the physical properties of natural original saline soil.

[0004] Therefore, it is necessary to design a device that can deeply study the influence of factors such as moisture, salt, temperature, etc. of natural saline soil on frost heave and melt collapse under natural environmental conditions, as well as the migration law of water and salt. This will have important practical significance and practical value for the promotion and development of in-situ testing of soil samples in saline land areas. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a portable on-site in-situ frost heave and dissolution detection device for saline soil, which can study the influence of moisture, salt and temperature of saline soil on frost heave and dissolution of natural saline soil under in-situ conditions, as well as the migration law of water and salt.

[0006] To achieve the above-mentioned purpose, the portable in-situ frost heave and dissolution detection device for saline soil of the present invention comprises a protective cover and a double-layer sample barrel, a load transmission column, a watering plate, a water supply system, a heating and cooling system, a column composite sensor signal processing system, a laser rangefinder display screen, a laser rangefinder signal transmission line and a laser rangefinder signal processing system arranged in the protective cover;

[0007] The test soil sample to be tested is located in a double-layer sample barrel, a sample barrel cover is provided at the top opening of the double-layer sample barrel, a standard load positioning rod is provided at the top of the load transmission column, the lower end of the load transmission column passes through the sample barrel cover and is placed on the anti-skid pad, the test soil sample to be tested is located in the double-layer sample barrel, the anti-skid pad is located on the test soil sample to be tested, a watering plate is fixed on the inner side of the sample barrel cover, and the watering plate is facing the test soil sample to be tested, an annular water belt is provided on the inner wall of the double-layer sample barrel, a water supply system is connected with the water inlet of the watering plate and the water inlet of the annular water belt, and a heating and cooling system is connected with the inner cavity of the side wall of the double-layer sample barrel;

[0008] Several layers of columnar composite sensors are buried from top to bottom inside the soil sample to be tested, and each layer of columnar composite sensors is arranged along the circumferential direction; the output end of each columnar composite sensor is connected to the columnar composite sensor signal processing system;

[0009] A laser rangefinder for detecting the distance between the sample barrel cover and the soil sample to be tested is arranged on the inner side of the sample barrel cover. The output signal of the laser rangefinder is processed by the laser rangefinder signal processing system through the laser rangefinder signal transmission line and then displayed on the laser rangefinder display screen.

[0010] The double-layer sample barrel comprises an upper double-layer organic glass sample barrel, a lower double-layer organic glass sample barrel and a sample barrel butt-jointing hoop bolt, wherein the upper double-layer organic glass sample barrel is located on the lower double-layer organic glass sample barrel, and a sample barrel horizontal joint insulation sealing strip is arranged between the upper double-layer organic glass sample barrel and the lower double-layer organic glass sample barrel, the sample barrel butt-jointing hoop bolt respectively connects the semicircular double-layer organic glass sample barrel cavities of the upper double-layer organic glass sample barrel and the lower double-layer organic glass sample barrel through the hoop, and a sample barrel longitudinal joint insulation sealing strip is arranged in the joint, and the upper sample barrel and the lower sample barrel are connected as a whole by the upper and lower sample barrel connecting bolts.

[0011] The loading device comprises a load transmission column, wherein a positioning rod is welded at the center of the top of the load transmission column, a center hole of the standard load is sleeved on the positioning rod, and the standard load is placed on the load transmission column.

[0012] The column type composite sensor is connected to the column type composite sensor signal processing system through the column type composite sensor signal transmission line. The column type composite sensor signal processing system is bonded to the outer wall of the double layer sample barrel. The column type composite sensor signal processing system is connected to the column type composite sensor signal display screen.

[0013] The cooling and heating system includes a first cooling and heating system, a second cooling and heating system, a medium output pipe and a medium input pipe, wherein the outlets of the first cooling and heating system and the second cooling and heating system are connected with the inlet of the medium input pipe, and the outlet of the medium input pipe is connected with the inlet of the upper sample barrel cavity and the inlet of the lower sample barrel cavity through the fourth valve and the third valve respectively; the inlets of the first cooling and heating system and the second cooling and heating system are connected with the outlet of the medium output pipe, and the inlet of the medium output pipe is connected with the outlet of the upper sample barrel cavity and the outlet of the lower sample barrel cavity through the first valve and the second valve respectively.

[0014] A sprinkler system water supply hose channel is provided on the cover plate of the sample barrel. The water supply system includes a sprinkler system water supply tank and a water hose water supply tank. The outlet of the sprinkler system water supply tank is connected through the sprinkler system water supply hose via the fifth valve and the first pressure gauge and then passes through the sprinkler system water supply hose channel to communicate with the sprinkler system nozzle.

[0015] An anti-skid pad is arranged at the bottom of the load transfer column, wherein the anti-skid pad is located on the soil sample to be tested.

[0016] The sprinkler plate is a ring structure, and a number of water outlet holes are evenly opened on the sprinkler plate.

[0017] The side of the protective cover is provided with a protective cover entrance and exit.

[0018] The present invention has the following beneficial effects:

[0019] During specific operation, the portable on-site in-situ frost heave and collapse detection device for saline soil described in the present invention applies a vertical additional load to the test soil sample through the standard load and the load transfer column, connects the refrigeration and heating system with the inner cavity of the side wall of the double-layer sample barrel, and introduces a medium into the inner cavity of the side wall of the double-layer sample barrel through the refrigeration and heating system to realize freeze-thaw cycle simulation of the test soil sample, and at the same time measures the salt expansion through a laser rangefinder; in addition, water is sprinkled on the test soil sample through the water supply system and the sprinkler plate, and a vertical additional load is applied to the test soil sample through the standard load and the load transfer column, and at the same time, the salt content, temperature and moisture of the test soil sample are detected through the column composite sensor, so as to realize real-time tracking of the stress field, chemical field, temperature field and seepage field of the test soil sample during the test, so as to realize a more realistic simulation of the physical properties of the original saline soil under natural rainfall conditions. An annular water belt is fixed on the side wall of the test soil sample to be tested. The water pressure in the annular water belt is adjusted to simulate the lateral pressure of the original soil. When measuring the amount of dissolution under rainfall conditions, the water pressure of the first pressure gauge is adjusted to simulate the actual natural rainfall, and the amount of dissolution of the soil sample is detected by the distance sensor. When detecting dissolution, the setting of the annular water belt can also effectively make up for the defects such as incomplete falling of the side of the soil sample caused by careless soil cutting operation of the ring knife during the preparation of the test soil sample. At this time, the water-filled thin-walled water belt can effectively fill the incomplete parts of the side wall of the soil sample, and the complete lateral confinement condition of the original soil can be achieved, so as to achieve a more accurate measurement of the physical parameters and engineering properties of the test soil sample without disturbing the original saline soil, avoiding the large errors caused by the measurement of reshaped soil in previous indoor tests, so as to provide more accurate physical parameters of saline soil strata for engineering research and engineering design in saline soil areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention;

[0021] Figure 2 It is a top view of the sample barrel cover plate 37 in the present invention;

[0022] Figure 3 It is a cross-sectional view of the AA section of the sample barrel cover plate 37 in the present invention;

[0023] Figure 4 It is a schematic structural diagram of the water sprinkling plate 55 in the present invention;

[0024] Figure 5 It is a schematic diagram of the cross-sectional structure of the side wall of the double-layer sample barrel in the present invention;

[0025] Figure 6 is a schematic diagram of the cross-sectional structure of the loading device in the present invention;

[0026] Figure 7 A perspective view of the soil cutting ring 48;

[0027] Figure 8 It is a sectional view of the BB section of the soil cutting ring 48 of the present invention;

[0028] Fig. 9 It is a schematic diagram of the connection between the column type composite sensor 51 and the column type composite sensor signal transmission line 20 in the present invention;

[0029] Fig.10 Schematic diagram of the deployment of the annular water belt 36 of the present invention

[0030] Fig.11 A schematic diagram of medium flow in the heating and cooling system of the present invention;

[0031] Fig.12 It is a schematic diagram of the structure of the protective cover 66 in the present invention.

[0032] Among them, 1 is the laser rangefinder display screen, 2 is the laser rangefinder signal processing system, 3 is the laser rangefinder signal transmission line, 4 is the pin, 5 is the upper sample barrel cavity outlet, 6 is the first valve, 7 is the medium output pipe, 8 is the upper and lower sample barrel connecting bolts, 9 is the pipeline medium flow direction indicator, 10 is the second valve, 11 is the lower sample barrel cavity outlet, 12 is the upper double-layer organic glass sample barrel, 13 is the lower double-layer organic glass sample barrel, 14 is the hoop, 15 is the sample barrel horizontal joint insulation sealing strip, 16 1 is the hoop bolt, 17 is the insulation sealing strip of the longitudinal joint of the sample barrel, 18 is the column composite sensor signal display screen, 19 is the column composite sensor signal processing system, 20 is the column composite sensor signal transmission line, 21 is the wire pipe, 22 is the lower sample barrel cavity inlet, 23 is the third valve, 24 is the upper sample barrel cavity inlet, 25 is the fourth valve, 26 is the medium input pipe, 27 is the fifth valve, 28 is the sprinkler system water supply box, 29 is the water hose water supply box, 30 is the sixth valve, 31 is the water hose water supply hose, 32 is the water supply hose of the sprinkler system, 33 is the first pressure gauge, 34 is the second pressure gauge, 35 is the water inlet of the water hose, 36 is the annular water hose, 37 is the cover of the sample barrel, 38 is the level, 39 is the laser rangefinder, 40 is the load transmission column, 41 is the standard load, 42 is the positioning rod, 43 is the water supply hose channel of the sprinkler system, 44 is the connecting screw of the sprinkler system, 45 is the inner wall of the double-layer organic glass sample barrel, 46 is the cavity of the double-layer organic glass sample barrel, 47 is the outer wall of the double-layer organic glass sample barrel, 48 is a soil cutting ring, 49 is a level tube, 50 is a ring blade foot, 51 is a columnar composite sensor, 52 is a test soil sample, 53 is a sprinkler system nozzle, 54 is a sprinkler system bracket, 55 is a sprinkler plate, 56 is an anti-skid pad, 57 is a sprinkler system end shaft, 58 is a first pin hole, 59 is a water outlet, 60 is a second pin hole, 61 is a first cooling and heating system, 62 is a second cooling and heating system, 63 is a hanging ring, 64 is a hook, 65 is a threading hole, 66 is a protective cover, and 67 is the entrance and exit of the protective cover. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0034] refer to Figures 1 to 12 The portable on-site in-situ frost heave and collapse detection device for saline soil of the present invention comprises a protective cover 66 and a double-layer sample barrel, a load transmission column 40, a watering plate 55, a water supply system, a cooling and heating system, a laser rangefinder display screen 1, a columnar composite sensor signal processing system 19, a laser rangefinder signal transmission line 3 and a laser rangefinder signal processing system 2 arranged in the protective cover 66; the test soil sample to be tested is located in the double-layer sample barrel, a sample barrel cover plate 37 is arranged at the top opening of the double-layer sample barrel, a standard load positioning rod 42 is arranged at the top of the load transmission column 40, the lower end of the load transmission column 40 passes through the sample barrel cover plate 37 and is placed on the anti-skid pad 56, the test soil sample to be tested is located in the double-layer sample barrel, the anti-skid pad 56 is located on the test soil sample to be tested, the watering plate 55 is fixed to the inner side of the sample barrel cover plate 37, and the watering plate 55 is facing the test soil sample. For testing soil samples, an annular water hose 36 is arranged on the inner wall of the double-layer sample barrel, the water supply system is connected with the sprinkler system nozzle 53 of the sprinkler plate 55 and the water hose inlet 35 of the annular water hose 36, and the cooling and heating system is connected with the inner cavity of the side wall of the double-layer sample barrel; a plurality of layers of columnar composite sensors 51 are buried from top to bottom in the test soil sample to be tested, and each layer of columnar composite sensors 51 is arranged along the circumferential direction; the output end of each columnar composite sensor 51 is connected with the columnar composite sensor signal processing system 19 through the columnar composite sensor signal transmission line 20; a laser rangefinder 39 for detecting the distance between the sample barrel cover plate 37 and the test soil sample 52 to be tested is arranged on the inner side of the sample barrel cover plate 37, and the output signal of the laser rangefinder 39 is displayed on the laser rangefinder display screen 1 after passing through the laser rangefinder signal transmission line 3 and the laser rangefinder signal processing system 2.

[0035] The double-layer sample barrel is composed of a double-layer organic glass sample barrel inner wall 45, a double-layer organic glass sample barrel cavity 46 and a double-layer organic glass sample barrel outer wall 47, and a second pin hole 60 is symmetrically provided on the top side.

[0036] The double-layer sample barrel comprises an upper double-layer organic glass sample barrel 12, a lower double-layer organic glass sample barrel 13 and a sample barrel butt-jointing hoop bolt 16, wherein the upper double-layer organic glass sample barrel 12 is located on the lower double-layer organic glass sample barrel 13, and a sample barrel horizontal joint insulation sealing strip 15 is arranged between the upper double-layer organic glass sample barrel 12 and the lower double-layer organic glass sample barrel 13, the sample barrel butt-jointing hoop bolt 16 respectively connects the two semicircular double-layer organic glass sample barrel cavities of the upper double-layer organic glass sample barrel 12 and the lower double-layer organic glass sample barrel 13 through the hoop 14, and a sample barrel longitudinal joint insulation sealing strip 17 is arranged in the joint, and the upper double-layer organic glass sample barrel 12 and the lower double-layer organic glass sample barrel 13 are connected as a whole by the upper and lower sample barrel connecting bolts 8.

[0037] The cooling and heating system includes a first cooling and heating system 61, a second cooling and heating system 62, a medium input pipe 26 and a medium output pipe 7, wherein the outlets of the first cooling and heating system 61 and the second cooling and heating system 62 are connected to the inlet of the medium input pipe 26, and the outlet of the medium input pipe 26 is connected to the upper sample barrel cavity inlet 24 and the lower sample barrel cavity inlet 22 respectively through the fourth valve 25 and the third valve 23; the inlets of the first cooling and heating system 61 and the second cooling and heating system 62 are connected to the outlet of the medium output pipe 7, and the inlet of the medium output pipe 7 is connected to the upper sample barrel cavity outlet 5 and the lower sample barrel cavity outlet 11 respectively through the first valve 6 and the second valve 10.

[0038] Specifically, an upper sample barrel cavity outlet 5 and an upper sample barrel cavity inlet 24 are provided on the side wall of the upper double-layer organic glass sample barrel 12, wherein a first valve 6 is provided at the upper sample barrel cavity outlet 5, and a fourth valve 25 is provided at the upper sample barrel cavity inlet 24; a lower sample barrel cavity outlet 11 and a lower sample barrel cavity inlet 22 are provided on the side wall of the lower double-layer organic glass sample barrel 13, wherein a third valve 23 is provided at the lower sample barrel cavity inlet 22, and a second valve 10 is provided at the lower sample barrel cavity outlet 11, wherein the cooling and heating system is divided into a first cooling and heating system 61 and a second cooling and heating system 62, wherein the first cooling and heating system 61 is connected with the upper sample barrel cavity outlet 5 and the upper sample barrel cavity inlet 24, and the second cooling and heating system 62 is connected with the lower sample barrel cavity outlet 11 and the lower sample barrel cavity inlet 22.

[0039] The loading device includes a load transmission column 40 , wherein a positioning rod 42 is welded at the center of the top of the load transmission column 40 , a center hole of a standard load 41 is sleeved on the positioning rod 42 , and the standard load 41 is placed on the load transmission column 40 .

[0040] The column type composite sensor 51 is connected to the column type composite sensor signal processing system 19 through the column type composite sensor signal transmission line 20 . The column type composite sensor signal processing system 19 is bonded to the outer wall of the double layer sample barrel. The column type composite sensor signal processing system 19 is connected to the column type composite sensor signal display screen 18 .

[0041] A sprinkler system water supply hose channel 43 is provided on the sample barrel cover 37, and the water supply system includes a sprinkler system water supply box 28 and a water hose water supply box 29. The outlet of the sprinkler system water supply box 28 is connected to one end of the sprinkler system water supply hose 32, and the other end of the sprinkler system water supply hose 32 passes through the fifth valve 27 and the first pressure gauge 33 and then passes through the sprinkler system water supply hose channel 43 to be connected to the sprinkler system nozzle 53; the outlet of the water hose water supply box 29 is connected to one end of the water hose water supply hose 31, and the other end of the water hose water supply hose 31 is connected to the water hose water inlet 35 through the sixth valve 30 and the second pressure gauge 34. Specifically, the sprinkler plate 55 is an annular structure, and a plurality of water outlet holes 59 are evenly provided on the sprinkler plate 55; the pin 4 passes through the second pin hole 60 and the first pin hole 58 on the sample barrel cover 37 to pin the sample barrel cover 37 to the upper double-layer organic glass sample barrel 12.

[0042] The side of the protective cover 66 is provided with a protective cover inlet and outlet 67; the present invention also includes a pipeline medium flow direction indicator 9 for indicating the flow direction of the medium; a level 38 is provided on the sample barrel cover 37;

[0043] The bottom of the sprinkler system bracket 54 passes through the sprinkler system end shaft 57 and the top is connected to the sample barrel cover 37 through the sprinkler system connecting screw 44.

[0044] The specific operation process of the present invention is:

[0045] Step 1: Installation of protective cover 66

[0046] A line is set within a set range around the test site, and a simple protective cover 66 is erected using scaffolding and colored strips of cloth or canvas. A protective cover entrance and exit 67 is opened on the leeward side of the protective cover 66 for the test staff to enter and exit, and lighting facilities are arranged inside the protective cover 66.

[0047] Step 2: Excavation of the circular working pit

[0048] Select test points at the test site and mark them, then dig a circular working pit 300mm away from the sample marking line. The width of the working pit should not be less than 800mm, and the depth should exceed the set sample height by 500mm.

[0049] Step 3: Preparation of test soil samples

[0050] The soil cutting ring 48 is accurately placed on the marked test soil sample contour line, and then 2 to 3 workers stand at equal intervals in the working pit to evenly chisel away excess soil along the outer wall of the soil cutting ring 48. When the ring blade foot 50 cuts down, the soil cutting ring 48 should be controlled by the level tube 49 embedded in the top of the ring along the annular direction to evenly cut down the soil until the set height. The cutting speed of the soil cutting ring 48 should be strictly controlled during the cutting process and should not be too fast.

[0051] Step 4: Installation of column type composite sensor 51

[0052] On the side of the prepared sample, the columnar composite sensor 51 is symmetrically arranged along the annular direction according to the designed depth. When installing the columnar composite sensor 51, first use a hand drill to drill a horizontal hole at the pre-calibrated design point along the radial direction of the sample. The hole diameter should be 5 to 10 mm larger than the outer diameter of the thin-walled metal casing. Then insert the thin-walled metal casing into the hole. Its inner diameter should be 1 to 3 mm larger than the maximum outer diameter of the columnar composite sensor 51. Then slowly insert the columnar composite sensor 51 connected to the columnar composite sensor signal transmission line 20 along the thin-walled metal casing. Then slowly pull out the thin-walled metal casing and use the chiseled salt soil and the vibrator to vibrate and fill the gap between the drill hole and the columnar composite sensor 51. Finally, insert the signal transmission line of each columnar composite sensor 51 into the wire tube 21.

[0053] Step 5: Fixing of the annular hose 36

[0054] After the annular water hose 36 is fixed on the side wall of the soil sample to be tested on which the columnar composite sensor 51 is installed, when fixing the annular water hose 36, the columnar composite sensor signal transmission line 20 buried in the soil sample to be tested should be passed through the annular water hose threading hole 65 first, and then the hanging rings 63 and hooks 64 at both ends of the annular water hose should be interlocked layer by layer, and the annular water hose 36 should be adjusted so that it does not appear wrinkled or twisted.

[0055] Step 6: Installation of the sample barrel

[0056] First, fix the longitudinal seam insulation sealing strip 17 of the sample barrel at the joint of the two semicircular cavities of the lower double-layer organic glass sample barrel 13, and apply adhesive on the surface of the strip, then connect the two semicircular cavities of the lower double-layer organic glass sample barrel 13 along the circumferential direction of the test soil sample, and then use the hoop 14 to firmly fix the longitudinal seam of the two semicircular cavities of the lower double-layer organic glass sample barrel 13 with the hoop bolt 16. Similarly, assemble the upper double-layer organic glass sample barrel 12, and then fix the horizontal seam insulation sealing strip 15 of the sample barrel at the joint of the upper double-layer organic glass sample barrel 12 and the lower double-layer organic glass sample barrel 13. Finally, fix the upper double-layer organic glass sample barrel 12 and the lower double-layer organic glass sample barrel 13 with the upper and lower sample barrel connecting bolts 8. After the sample barrels are assembled, a watertightness test is carried out to ensure that they have good sealing properties.

[0057] Step 7: Installation of sprinkler system

[0058] First, connect the sprinkler system nozzle 53 to the sprinkler system water supply hose 32, and then pass the sprinkler system end shaft 57 through the sprinkler system bracket 54. Then fix the sprinkler system bracket 54 and the sample barrel cover 37 through the sprinkler system connecting screw 44, and manually move the sprinkler system to observe the flexibility of the sprinkler system end shaft 57 swinging on the sprinkler system bracket 54 to ensure that the sprinkler plate 55 can remain basically horizontal after it is stable.

[0059] Step 8: Installation of the sample barrel cover 37

[0060] Insert the sample barrel cover 37 horizontally into the upper double-layer organic glass sample barrel 12, and move the sample barrel cover 37 up and down so that the second pin hole 60 is aligned with the first pin hole 58, and then insert the pin 4 to fix the sprinkler system on the double-layer sample barrel, and adjust the height of the two ends of the sample barrel cover 37 so that the bubble of the level 38 is centered, and take simple measures to fix the end of the sample barrel cover 37 perpendicular to the axial direction of the pin hole, so that the sample barrel cover 37 can be kept as horizontal as possible.

[0061] Step 9 Installation of laser rangefinder 39

[0062] First, the laser rangefinder 39 is embedded in the reserved hole on the sample barrel cover 37, and then the laser rangefinder 39 is connected to the laser rangefinder signal processing system 2 by the laser rangefinder signal transmission line 3.

[0063] Step 10: Loading device installation

[0064] First, the load transfer column 40 is placed on the anti-slip pad 56, and then the standard load 41 is sleeved on the positioning rod 42 and placed on the load transfer column 40, so that the total mass of the load system reaches the designed test initial load value.

[0065] Step 11: Compressed air is filled into the annular water hose 36 (for frost heave detection)

[0066] When the device is used for frost heave detection, the test site should also be additionally equipped with air compression equipment, and the water hose inlet 35 should be connected to the air outlet of the air compression equipment. Since a large negative temperature will appear during the freeze-thaw cycle of the frost heave test, if the annular water hose 36 is filled with water, it will cause the annular water hose 36 to frost heave, thereby damaging the annular water hose 36 and causing lateral squeezing of the test soil sample, affecting the accuracy of the test results.

[0067] Step 12: Connection of water supply system (for dissolution detection)

[0068] First, connect the sprinkler system water supply hose 32 to the sprinkler system water supply tank 28, and install the fifth valve 27 and the first pressure gauge 33 at the end of the sprinkler system water supply tank 28, and then use the water hose water supply hose 31 to connect the water hose inlet 35 to the water hose supply tank 29, and set the sixth valve 30 and the second pressure gauge 34 at the end of the water hose supply tank 29.

[0069] Step 13: Connection of cooling and heating system

[0070] The first cooling and heating system 61 and the second cooling and heating system 62 are connected to the cavity inlets and outlets of the upper double-layer organic glass sample barrel 12 and the lower double-layer organic glass sample barrel 13 by using the medium output pipe 7 and the medium input pipe 26 respectively;

[0071] The columnar composite sensor 51 is a highly integrated high-sensitivity composite sensor that integrates salt, temperature and moisture measurements. The signal transmission line 20 of the columnar composite sensor passes through the threading hole 65 of the annular water hose 36 and then enters the wire tube 21 to be led out from the joint of the upper and lower sample barrels. When leading out, a hole slightly larger than the diameter of the wire tube 21 is opened on the horizontal joint insulation sealing strip 15 of the sample barrel to lead out the wire tube 21, and the wire hole gap is sealed with sealant.

[0072] Step 14 Determination of frost heave under seasonal freeze-thaw cycles

[0073] According to the results of the meteorological data survey and the design plan, the temperature gradient of the freeze-thaw cycle, the number of freeze-thaw cycles, and the duration of frost heave and melt collapse in each cycle are formulated, and the duration t1 of the freeze-thaw cycle freeze-thaw process is determined. After the freeze-thaw process is completed, the first cooling and heating system 61 and the second cooling and heating system 62 are adjusted respectively, and the medium is converted so that the medium temperature reaches the maximum value of the local temperature in the test area, and the temperature is allowed to rise to simulate the natural phenomenon of the gradual increase in soil temperature in the next year. This thawing process is maintained until the soil sample temperature reaches the maximum value of the local temperature in the test area, and the duration is t2, that is, t1+t2 is a freeze-thaw cycle. The values ​​of salt, temperature, moisture and frost heave are recorded every half an hour. According to the monitoring data, the influencing factors and the change law of frost heave of saline soil after multiple freeze-thaw cycles are analyzed, and the freeze-thaw cycle mechanism of the original saline soil is explored.

[0074] According to the upper load level set in the test plan, the sample is subjected to multiple freeze-thaw cycles under the action of the same level of vertical load. The annular water hose 36 is filled with compressed air to fill the gap between the inner wall 45 of the double-layer organic glass sample barrel and the test soil sample 52, and a certain confining pressure is provided to the test soil sample 52. The humidity of the compressed air should be determined by preliminary tests to ensure that heat can be effectively transferred. During the frost heave process, the medium in the sample barrel cavity is liquid nitrogen, and during the thawing process, the medium in the sample barrel cavity is hot water. During each freeze-thaw cycle, after the test starts, the column composite sensor is recorded every 2 minutes within 0.5 hours. The readings of the column composite sensor 51 and the laser rangefinder 39 are recorded every 5 minutes within 0.5 to 1 hour. Similarly, the readings are recorded every 20 minutes within 1 hour to 5 hours, and every 60 minutes from 5 hours to the end of the test. The data are analyzed and processed by computer in time, and the frost heave trend of the next load gradient is predicted. When the salt expansion accumulation of the saline soil is no longer obvious, it means that the saline soil has reached a state of equilibrium during the freeze-thaw cycle. The test can be stopped, the test equipment and instruments can be removed, and the test data can be analyzed and sorted.

[0075] Step 15 Determination of the amount of solution under rainfall conditions

[0076] According to the results of the meteorological data investigation, the parameters of the experimental simulation such as rainfall amount, rainfall intensity and duration are formulated, and the experimental simulation is carried out with the help of computer numerical simulation software to verify the reliability of the proposed relevant rainfall parameters, and strive to make the test environment close to natural rainfall conditions; and the sample temperature during the test is set, and it is controlled to a constant value by the fluid medium in the double-layer sample barrel cavity.

[0077] The dissolution and collapse properties of saline soil were studied on the test soil samples. When studying the relationship between rainfall and dissolution and collapse, the water output of the water outlet hole 59 of the sprinkler plate was controlled by the first pressure gauge 33 and the fifth valve 27 installed on the water supply hose 32 of the sprinkler system; the water in the annular water belt 36 had a certain pressure to simulate the actual lateral pressure on the test soil sample and realize the test condition of full lateral limitation; during the test process under the setting of rainfall conditions, under the action of the same level of load, after the test starts timing, within 0.5h, the readings of the column composite sensor 51 and the laser rangefinder 39 are recorded every 2min, within 0.5h to 1h, the readings of the column composite sensor 51 and the laser rangefinder 39 are recorded every 5min, similarly, within 1h to 5h, the readings are recorded every 20min, and from 5h to the end of the test, the readings are recorded every 60min. According to the requirements of the specifications, the test can be appropriately ended in advance, and the data are timely summarized and sorted out to study the relationship between rainfall and the change in soil height, and then comprehensively analyze the dissolution and collapse properties of saline soil.

Claims

1. A portable in-situ frost heave and dissolution detection device for saline soil, characterized in that: It comprises a protective cover (66), a double-layer sample barrel arranged in the protective cover (66), a load transmission column (40), a watering plate (55), a water supply system, a heating and cooling system, a columnar composite sensor signal processing system (19), a laser rangefinder signal transmission line (3), a laser rangefinder display screen (1) and a laser rangefinder signal processing system (2); A sample barrel cover plate (37) is arranged at the top opening of the double-layer sample barrel, a positioning rod (42) is arranged at the top of the load transmission column (40), the lower end of the load transmission column (40) passes through the sample barrel cover plate (37) and is placed on the anti-skid pad (56), the test soil sample to be tested is located in the double-layer sample barrel, the anti-skid pad (56) is located on the test soil sample to be tested, a water sprinkling plate (55) is fixed on the inner side of the sample barrel cover plate (37), and the water sprinkling plate (55) is facing the test soil sample to be tested, an annular water belt (36) is arranged on the inner wall of the double-layer sample barrel, a water supply system is connected with the water inlet of the water sprinkling plate (55) and the water inlet of the annular water belt (36), and a heating and cooling system is connected with the inner cavity of the side wall of the double-layer sample barrel; A plurality of layers of columnar composite sensors (51) are buried from top to bottom inside the soil sample to be tested, and each layer of columnar composite sensors (51) is arranged along the circumferential direction; the output end of each columnar composite sensor (51) is connected to a columnar composite sensor signal processing system (19); A laser rangefinder (39) for detecting the distance between the sample barrel cover (37) and the soil sample to be tested is arranged on the inner side of the sample barrel cover (37); an output signal of the laser rangefinder (39) is processed by a laser rangefinder signal processing system (2) through a laser rangefinder signal transmission line (3) and then displayed on a laser rangefinder display screen (1); The loading device comprises a standard load (41), wherein a positioning rod (42) is welded at the center of the top of the load transmission column (40), the center hole of the standard load (41) is sleeved on the positioning rod (42), and the standard load (41) is placed on the load transmission column (40); The column type composite sensor (51) is connected to a column type composite sensor signal processing system (19) via a column type composite sensor signal transmission line (20); the column type composite sensor signal processing system (19) is bonded to the outer wall of the double-layer sample barrel; and the column type composite sensor signal processing system (19) is connected to a column type composite sensor signal display screen (18).

2. The portable in-situ frost heave and dissolution detection device for saline soil according to claim 1 is characterized in that: The double-layer sample barrel comprises an upper double-layer organic glass sample barrel (12), a lower double-layer organic glass sample barrel (13) and a hoop bolt (16), wherein the upper double-layer organic glass sample barrel (12) is located on the lower double-layer organic glass sample barrel (13), and a sample barrel horizontal joint insulation sealing strip (15) is arranged between the upper double-layer organic glass sample barrel (12) and the lower double-layer organic glass sample barrel (13), and the sample barrel butt hoop bolt (16) connects the semicircular double-layer organic glass sample barrel cavities of the upper double-layer organic glass sample barrel (12) and the lower double-layer organic glass sample barrel (13) respectively through a hoop (14), and a sample barrel longitudinal joint insulation sealing strip (17) is arranged in the joint, and the upper double-layer organic glass sample barrel (12) and the lower double-layer organic glass sample barrel (13) are connected as a whole by upper and lower double-layer organic glass sample barrel connecting bolts (8).

3. The portable in-situ frost heave and dissolution detection device for saline soil according to claim 1 is characterized in that: The heating and cooling system comprises a first cooling and heating system (61), a second cooling and heating system (62), a medium input pipe (26) and a medium output pipe (7), wherein the outlets of the first cooling and heating system (61) and the second cooling and heating system (62) are connected to the inlet of the medium input pipe (26), and the outlet of the medium input pipe (26) is respectively connected to the inlet (24) of the upper sample barrel cavity and the inlet (22) of the lower sample barrel cavity through a fourth valve (25) and a third valve (23); the inlets of the first cooling and heating system (61) and the second cooling and heating system (62) are connected to the outlet of the medium output pipe (7), and the inlet of the medium output pipe (7) is respectively connected to the outlet (5) of the upper sample barrel cavity and the outlet (11) of the lower sample barrel cavity through a first valve (6) and a second valve (10).

4. The portable in-situ frost heave and dissolution detection device for saline soil according to claim 1 is characterized in that: A sprinkler system water supply hose channel (43) is provided on the sample barrel cover (37). The water supply system includes a sprinkler system water supply tank (28) and a water hose water supply tank (29). The outlet of the sprinkler system water supply tank (28) is connected to the sprinkler system nozzle (53) through the sprinkler system water supply hose (32), the fifth valve (27) and the first pressure gauge (33), and then through the sprinkler system water supply hose channel (43).

5. The portable in-situ frost heave and dissolution detection device for saline soil according to claim 1 is characterized in that: An anti-skid pad (56) is provided at the bottom of the load transmission column (40), wherein the anti-skid pad (56) is located on the soil sample (52) to be tested.

6. The portable in-situ frost heave and dissolution detection device for saline soil according to claim 1 is characterized in that: The water sprinkling plate (55) is an annular structure, and a plurality of water outlet holes (59) are evenly arranged on the water sprinkling plate (55).

7. The portable in-situ frost heave and dissolution detection device for saline soil according to claim 1 is characterized in that: A protection cover inlet and outlet (67) is provided on the side of the protection cover (66).

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