CN210154987U - Frozen soil water vapor migration monitoring devices - Google Patents
Frozen soil water vapor migration monitoring devices Download PDFInfo
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- CN210154987U CN210154987U CN201920407496.2U CN201920407496U CN210154987U CN 210154987 U CN210154987 U CN 210154987U CN 201920407496 U CN201920407496 U CN 201920407496U CN 210154987 U CN210154987 U CN 210154987U
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Abstract
The utility model discloses a frozen soil water vapor migration monitoring device, which comprises a sample body, a temperature and humidity regulating mechanism and a monitoring mechanism; the sample body comprises a soil sample, an inner cylinder for placing the soil sample, an outer cylinder sleeved on the outer side of the inner cylinder and heat insulation cotton wrapped on the periphery of the outer cylinder; the temperature and humidity regulating mechanism comprises an upper temperature control disc, a lower temperature control disc and a water supplementing unit, the upper temperature control disc is placed in the inner cylinder, the upper temperature control disc covers the soil sample, the lower temperature control disc is placed in the outer cylinder, an isolation layer is reserved between the lower temperature control disc and the bottom of the soil sample, and the water supplementing unit comprises a water guide pipe and is connected to the isolation layer through the water guide pipe; monitoring mechanism includes temperature sensor, moisture sensor, displacement meter and pressure gauge, and temperature sensor and moisture sensor run through the lateral wall of inner tube and urceolus and extend to soil sample inside, and displacement meter and pressure gauge are installed in soil sample top. The utility model discloses a device can realize the research to frozen soil water (vapour) migration law under the one-dimensional temperature gradient, gos deep into the little frozen swelling mechanism that reveals unsaturated coarse grained soil.
Description
Technical Field
The utility model belongs to geotechnological low temperature test field, concretely relates to frozen soil steam migration monitoring devices.
Background
By the end of 2016, the mileage of the high-speed railway reaches 22980 km, the passenger capacity accounts for 43.4 percent of the specific gravity of the railway, and nearly 75 percent of lines exist in the northern freezing region. In the process of construction and operation of a high-speed railway in a cold area, frost heaving of soil can seriously affect the stability of engineering in the cold area, and even engineering diseases such as cracking, landslide and water seepage can be caused. The research on the stability of the roadbed is always a key scientific problem closely related to engineering practice and the theory of permafrost science.
In the pore structure of more developed coarse-grained soils, liquid water migration due to capillary forces is more limited, for example, in the rigid ice model of Miller (1978) and the segregation potential theory of Konrad and morgenstrin (1981), but as an object of the previous work, the water moisture migration contribution to the water content change was ignored. Coarse-grained soil has structural characteristics different from fine-grained soil, strict requirements of high-speed railway operation smoothness on roadbed deformation and the particularity that shallow coarse-grained soil filler is slightly frozen and swelled to be different from traditional frozen and swelled are one of research hotspots of cold region engineering in recent years. How to forecast the engineering diseases in advance and give corresponding prevention and control measures cannot be known accurately that water vapor migrates to ice in the process of the micro frost heaving of coarse-grained soil.
At present, no mature device exists for the research of frozen soil water vapor migration. For simple testing of final moisture content and deformation results, assembly or modification of conventional frost heave equipment is only marginal. However, different research results cannot be compared transversely, and the frost heaving process cannot be subjected to inversion analysis, so that the knowledge of the micro frost heaving and the development of cold region engineering are severely restricted.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a frozen soil steam migration monitoring devices, the device can realize the research to frozen soil water (vapour) migration law under the one-dimensional temperature gradient, and the mechanism that expands is frozen a little of deeply disclosing unsaturated coarse grained soil to it is multi-functional, high accuracy, extensively suitable for.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
a frozen soil water vapor migration monitoring device comprises a sample body, a temperature and humidity regulating and controlling mechanism and a monitoring mechanism;
the sample body comprises a soil sample, an inner cylinder for placing the soil sample, an outer cylinder sleeved on the outer side of the inner cylinder and heat insulation cotton wrapped on the periphery of the outer cylinder;
the temperature and humidity regulating mechanism comprises an upper temperature control disc, a lower temperature control disc and a water supplementing unit, the upper temperature control disc is placed in the inner cylinder and covers the upper part of the soil sample, the lower temperature control disc is placed in the outer cylinder, an isolation layer is reserved between the lower temperature control disc and the bottom of the soil sample, and the water supplementing unit comprises a water guide pipe and is connected to the isolation layer through the water guide pipe;
monitoring mechanism includes temperature sensor, moisture sensor, displacement meter and pressure gauge, temperature sensor and moisture sensor run through the lateral wall of inner tube and urceolus and extend to soil sample inside, displacement meter and pressure gauge are installed in soil sample top.
Preferably, the side walls of the inner cylinder and the outer cylinder are provided with mounting holes which are arranged in pairs, each pair of mounting holes comprises a plurality of independent holes formed in the side wall of the inner cylinder and a strip-shaped hole formed in the side wall of the outer cylinder, the strip-shaped holes are matched with the arrangement paths of the independent holes, and the temperature sensor or the moisture sensor penetrates through the independent holes and the strip-shaped holes and then extends into the soil sample in a use state.
Preferably, the inner cylinder and the outer cylinder are both cylinders with openings at two ends and hollow interiors, the plurality of independent holes in each pair of mounting holes are arranged along the height direction of the cylinders, the strip-shaped holes extend along the height direction of the cylinders, and the total length of the extension of the strip-shaped holes is greater than the total length of the arrangement of the plurality of independent holes.
Preferably, the inner diameter of the outer cylinder is 2 to 3mm larger than the outer diameter of the inner cylinder.
As preferred, the lateral wall of going up the accuse temperature dish with the inner wall of inner tube pastes and leans on, go up the accuse temperature dish and include that the superpose is fixed first go up dish and first dish, and the superpose position of first dish and first dish is installed at the first dish of going up, the coil pipe is connected with the cold bath hose, be equipped with the screw hole on the first dish of going up, the screw hole is connected with monitoring platform, the installation position of displacement meter or pressure gauge with monitoring platform suits.
As preferred, the lateral wall of accuse temperature dish down with the inner wall of urceolus pastes and leans on, accuse temperature dish down includes that the superpose is fixed the second and is gone up dish and second dish down, and the superpose position of dish and second dish down installs the coil pipe on the second, the coil pipe is connected with the cold bath hose, be equipped with on dish and the second dish down on the second and be used for dodging the moisturizing passageway of aqueduct.
Preferably, the thickness of the isolation layer is 2 cm.
Preferably, a permeable stone or a porous plate is placed in the isolation layer.
Preferably, the frozen soil water vapor migration monitoring device further comprises a supporting mechanism, wherein the supporting mechanism comprises a top cover, a base, a top plate and a bottom plate;
the top cap is connected the top of urceolus, the base is connected the bottom of urceolus, be connected with the support between top cap and the base, top cap and base all include first ring and second ring, the interior circle radius of first ring is less than the interior circle radius of second ring, the terminal surface and the first ring of urceolus offset, just the lateral wall of urceolus is subject to the second ring.
Preferably, the top plate and the bottom plate are both flat plates, the bottom plate is connected with the top plate through a fixing column, a supporting leg is connected between the first circular ring and the bottom plate, and a threaded hole used for connecting a displacement meter or a pressure meter is formed in the top plate.
Compared with the prior art, the utility model provides a frozen soil steam migration monitoring devices includes following beneficial effect:
1. the sample body comprises two concentric sample cylinders, and vaseline is coated between the walls of the inner cylinder and the outer cylinder for lubrication, so that the phenomenon that the upper temperature control plate cannot move freely due to water accumulation into ice to influence the generation and measurement of frost heaving quantity is avoided; meanwhile, the method has a positive effect on preventing the environmental heat from being transmitted along the radial direction of the soil sample.
2. An isolation layer is arranged between the lower temperature control disc and the bottom of the soil sample, and permeable stones or porous plates can be respectively placed according to research objects (liquid water and gaseous water), so that the migration rule of different phase water in the frozen state of the soil sample can be researched.
3. The instruments for measuring the main parameters of the test all adopt uniform diameters and are fixed on the mounting plate matched with the instruments, so that the multi-parameter measurement test of one device can be realized, and the device has wide applicability.
4. Adopt displacement meter measurement frost heaving volume, the communication line is mutual with data acquisition end in real time, can catch the soil sample frost heaving overall process, and also has great promotion in measurement accuracy.
5. The acquisition of each test data (temperature, moisture, displacement and frost heaving force) is automatically carried out by adopting a data acquisition instrument, so that the problem that the normal reading cannot be carried out in the test process is solved, and the dynamism is really realized; the man-made workload is greatly reduced; accidental errors caused by manual reading are avoided.
Drawings
FIG. 1 is a cross-sectional view of the sample body, the temperature and humidity control mechanism and part of the support mechanism of the present invention;
FIG. 2 is a schematic structural view of the frozen soil water vapor migration monitoring device of the present invention;
FIG. 3 is an exploded view of part of the structure of the frozen soil water vapor migration monitoring device of the present invention;
FIG. 4 is a schematic view of the connection structure of the upper temperature control plate and the displacement meter of the present invention;
FIG. 5 is a schematic structural view of the water replenishing unit of the present invention;
fig. 6 is a schematic view of the connection structure of the pressure gauge of the present invention.
1. A cold bath hose; 2. a moisture sensor; 3. an inner barrel; 4. a support; 5. an outer cylinder; 6. a lower temperature control plate; 7. a second circular ring; 8. a top cover; 9. an upper temperature control disc; 10. a first independent aperture; 11. a temperature sensor; 12. a first bar-shaped hole; 131. a first screw; 132. a second screw; 133. a third screw; 14. a first circular ring; 15. supporting legs; 16. a water replenishing unit; 1601. a guide rail; 1602. a slider; 1603. a Ma's flask graduated cylinder; 1604. a hoop; 18. an isolation layer; 19. a groove; 201. a displacement meter communication line; 202. a pressure gauge communication line; 21. a monitoring platform; 22. heat preservation cotton; 23. a base plate; 241. a first nut; 242. a second nut; 25. a top plate; 26. a displacement meter; 27. fixing a column; 281. a first threaded hole; 282. a second threaded hole; 29. circulating the inlet and the outlet; 30. a coil pipe; 311. a first thread; 312. a second thread; 32. mounting a plate; 33. soil sampling; 34. and a pressure gauge.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
It is noted that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present; when an element is referred to as being "secured" to another element, it can be directly secured to the other element or intervening elements may also be present.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
As shown in fig. 1 and 2, the frozen soil water vapor migration monitoring device comprises a sample body, a temperature and humidity regulating mechanism and a monitoring mechanism.
The sample body of the present embodiment includes a soil sample 33, an inner cylinder 3, an outer cylinder 5, and heat-insulating cotton 22. The soil sample 33 is placed in the sample inner cylinder 3, the outer cylinder 5 is sleeved on the outer side of the inner cylinder 3, and the heat insulation cotton 22 is wrapped on the periphery of the outer cylinder 5.
The temperature and humidity regulating mechanism comprises an upper temperature control plate 9, a lower temperature control plate 6 and a water supplementing unit 16, the upper temperature control plate 9 is placed in the inner barrel 3, the upper temperature control plate 9 covers the soil sample 33, the lower temperature control plate 6 is placed in the outer barrel 5, an isolation layer 18 is reserved between the lower temperature control plate 6 and the bottom of the soil sample 33, and the water supplementing unit 16 comprises a water guide pipe and is connected to the isolation layer 18 through the water guide pipe;
the monitoring mechanism comprises a temperature sensor 11, a moisture sensor 2, a displacement meter 26 and a pressure gauge 34, wherein the temperature sensor 11 and the moisture sensor 2 penetrate through the side walls of the inner cylinder 3 and the outer cylinder 5 and extend towards the inside of the soil sample 33, and the displacement meter 26 and the pressure gauge 34 are installed above the soil sample 33.
The sample body of the embodiment adopts a concentric double-sleeve design, and the isolation layer 18 is reserved at the bottom of the soil sample 33, so that the purpose of researching the migration of gaseous water is realized; the interference of the radial propagation of the environmental heat along the soil sample to the temperature field is weakened; the most important thing is to solve the problem that the inner drum 3 and the upper temperature control plate 9 can not move freely due to the freezing of the moisture and the ice formation. The device can realize the research on the water (steam) migration rule of the frozen soil under the one-dimensional temperature gradient, deeply reveals the micro-freezing and swelling mechanism of unsaturated coarse-grained soil, and has the characteristics of multiple functions, high precision, wide application and the like.
In one embodiment, vaseline is uniformly coated at the mutual contact position of the inner cylinder 3 and the outer cylinder 5 for lubrication, so that the inhibition of frictional resistance on frost heaving deformation of soil is eliminated; in addition, when filling, strictly controlling the initial water content, and dividing into five layers according to the calculated compaction degree for compaction forming; the concrete size of soil sample 33 is diameter 12cm, height 15cm, can carry out laboratory ratio according to operating condition, also can directly adopt undisturbed soil.
The inner cylinder 3 is made of organic glass, has good weather resistance, higher surface hardness, good low-temperature performance and easy processing, and meets various index requirements of a frost heaving test; the specific size of the inner cylinder 3 is 12cm of inner diameter, 1cm of wall thickness and 20cm of height; in the installation process, vaseline is correspondingly coated on the outer wall of the outer cylinder for lubrication, and the outer cylinder is sleeved with the outer cylinder 5.
The outer cylinder 5 is also made of organic glass, the height of the outer cylinder 5 is higher than that of the inner cylinder 3, and the size of the outer cylinder 5 is 14cm in inner diameter, 1cm in wall thickness and 30cm in height; the inner diameter of the outer cylinder 5 is allowed to have a tolerance of 2 to 3mm (only a small value), that is, the inner diameter of the outer cylinder 5 is allowed to be 2 to 3mm larger than the outer diameter of the inner cylinder 3. The reason why the inner diameter of the outer cylinder 5 is provided with an excessively large tolerance is that: the outward micro-tympany deformation caused by resisting frost heaving force when the side limiting force of the inner cylinder 3 is insufficient is avoided, the mutual contact extrusion of the inner cylinder and the outer cylinder can generate larger friction resistance to influence the generation and measurement of frost heaving, and therefore a certain gap is needed to enable the inner cylinder 3 in the inner cylinder to move freely.
In one embodiment, in order to facilitate installation of various sensors, the side walls of the inner barrel 3 and the outer barrel 5 are provided with installation holes arranged in pairs, each pair of installation holes comprises a plurality of independent holes formed in the side wall of the inner barrel 3 and a strip-shaped hole formed in the side wall of the outer barrel 5, the strip-shaped hole is adapted to the arrangement path of the independent holes, and the temperature sensor 11 or the moisture sensor 2 penetrates through the independent holes and the strip-shaped hole and then extends into the soil sample 33 in a use state. It will be readily appreciated that when describing mounting holes arranged in pairs, the individual holes are considered as one piece and in paired relation with the bar holes. The number of independent holes in each pair of mounting holes is set according to the requirement.
The arrangement direction of the independent holes can be adjusted according to design requirements, and the independent holes can be arranged linearly or in a staggered manner. In an embodiment, the inner cylinder 3 and the outer cylinder 5 are both cylinders with openings at both ends and hollow interiors, the plurality of independent holes in each pair of mounting holes are arranged along the height direction of the cylinders (direction a in fig. 1 is the height direction of the cylinders), the strip-shaped holes extend along the height direction of the cylinders, and the total length of the strip-shaped holes is greater than the total length of the independent holes.
As shown in fig. 3, in the present embodiment, 2 pairs of mounting holes are formed in the side walls of the inner cylinder 3 and the outer cylinder 5, one pair of mounting holes is used for mounting the temperature sensor 11, and the other pair of mounting holes is used for mounting the moisture sensor 2. Specifically, the pair of mounting holes for mounting the temperature sensor 11 are: interval 15mm that sets up in one side of inner tube 3, the first independent hole 10 of internal diameter 5mm, first independent hole 10 is the round hole that is used for installing temperature sensor 11, and the total length of arranging of a plurality of first independent holes 10 is L1, be equipped with wide 10mm in the corresponding position of urceolus 5, first bar hole 12 of height 150mm, the total length of extension of this first bar hole 12 is L2, in order to avoid interfering soil sample 33 frost heaving deformation, it is greater than the total length of arranging L1 to set up the total length of extension L2.
The other pair of mounting holes for mounting the moisture sensor 2 is: set up the second independent hole with first independent hole 10 opposite side on the lateral wall of inner tube 3, because moisture sensor 2 has two detection heads, so set up the second independent hole and be two vertical interval 30mm, the square through-hole (not shown in the figure) of length 5mm, height 2mm of horizontal clear interval 8mm, set up wide 20mm, the second bar hole (not shown in the figure) of height 150mm on the lateral wall of urceolus 5.
The same extending total length of the second strip-shaped holes is larger than the arrangement total length of the plurality of second independent holes, so that a space is reserved for frost heaving displacement, the safety of the sensor is protected, the outer barrel 5 mainly plays an auxiliary role, and no strict requirement is imposed on the lateral limiting rigidity, so that the strip-shaped holes are properly widened to reserve an activity space; the angle should be adjusted during the sleeving process to form a complete sensor mounting hole.
In one embodiment, the thermal insulation cotton 22 is made of polystyrene material, and the thermal conductivity coefficient is less than 0.03W/m/K, so that the transverse loss of the soil sample heat can be effectively reduced; the periphery of the outer cylinder 5 is wrapped by a plurality of circles; after the wrapping is finished, the wrapping is wound by a transparent wide adhesive tape, so that the tightness of the wrapping is ensured, and the monitoring environment is further improved; it is worth noting that the location of sensor deployment should be noted during the wrapping process.
In one embodiment, as shown in fig. 4, the upper temperature control plate 9 is made of T5 high-quality aluminum material, so as to ensure its excellent heat-conducting property; the lower surface of the inner cylinder is closed, smooth and flat, is tightly contacted with the soil sample 33, the side surface of the inner cylinder is attached to the inner wall of the inner cylinder 3, and the inner cylinder is a cylinder with the diameter of 120mm and the height of 40 mm.
The upper temperature control plate 9 is assembled by stacking and fixing a first upper plate and a first lower plate, wherein the upper plate and the lower plate are respectively 2cm thick and are screwed by 4 third screws 133 of M4X 30; a coil pipe 30 which is in bidirectional surrounding, single-in and single-out is arranged between the first upper disc and the first lower disc in advance, so that the temperature uniformity of all positions of the upper temperature control disc 9 can be ensured to the greatest extent; the refrigerant circulating liquid enters and exits the upper temperature control plate 9 through the circulating inlet and outlet 29 and is supplied by the external temperature control cold bath box; the external temperature control cold bath box forms a closed loop with the upper temperature control plate 9 through the cold bath hose 1 to realize temperature control.
The refrigerant circulating liquid in the embodiment adopts high-quality antifreeze liquid, the freezing point is easy to control, and the refrigerant circulating liquid can still keep a liquid state at the lowest temperature of-60 ℃; the metal antirust agent is added in the coil pipe, a protective film is formed on the surface of metal, and the coil pipe 30 cannot be rusted or even blocked in the long-term use process.
The circulating inlet and outlet 29 is protruded out of the upper surface of the upper temperature control plate 9, and the upper port of the circulating inlet and outlet is slightly smaller than the inner diameter of the cold bath hose 1; in the installation process, the circulating inlet and outlet 29 is extruded into the cold bath hose 1 and is fastened by a self-locking nylon cable tie or an installation nut, so that the separation of the circulating inlet and outlet and the cold bath hose is prevented in the pumping process, and potential safety hazards are avoided.
In order to improve the compactness of the connection of the components, a second threaded hole 282 is formed in the upper surface of the upper temperature control plate 9, a second thread 312 used in a matching mode is connected with the second threaded hole in a screwing mode, in the embodiment, the second threaded hole 282 is in threaded connection with a monitoring platform 21, the monitoring platform 21 indirectly reflects the frost heaving deformation of the soil sample, and the installation orientations of the displacement meter 26 and the pressure meter 34 are matched with the monitoring platform so as to obtain the most accurate monitoring data.
The cold bath hose 1 is a low-temperature-resistant silica gel translucent tube, has good rebound resilience and smooth inner wall, and cannot cause unsmooth water flow due to bending; can still keep certain flexibility under the low temperature state; the chemical property is good, and the refrigerant circulating liquid of each component is suitable to pass through.
In one embodiment, the side wall of the lower temperature control plate 6 is attached to the inner wall of the outer cylinder 5, the lower temperature control plate 6 comprises a second upper plate and a second lower plate which are fixedly overlapped, and a coil pipe is installed at the overlapped part of the second upper plate and the second lower plate and connected with a cold bath hose. Since the structure of the lower temperature control plate 6 in this embodiment is substantially the same as that of the upper temperature control plate 9, the assembly form of the lower temperature control plate and the installation of the coil pipe are not described in detail.
Unlike the upper temperature-control plate 9, the lower temperature-control plate 6 is a cylinder with a diameter of 140mm x a height of 40 mm. The upper surface of the lower temperature control plate 6 is an open filter screen (as shown in fig. 3), the circulating inlet and outlet 29 is arranged on the lower surface, and the circulating inlet and outlet circulates to another external temperature control cold bath box through a cold bath hose to independently control the temperature so as to meet the simulation of more different working conditions; and a water supplementing channel (not shown in the figure) is additionally arranged in the upper temperature control plate 9 compared with the upper temperature control plate 9 and is used for avoiding the water guide pipe so as to realize the simulation of the underground water condition.
In one embodiment, the isolation layer 18 is provided with a thickness of 2cm, and a permeable stone or a porous plate is provided according to the study object (gaseous water, liquid water).
Specifically, when the research object is liquid water, a permeable stone with the thickness of 2cm is arranged at the position of the isolation layer 18, the water replenishing height is adjusted, the bottom surface of the soil sample 33 is guaranteed to be submerged, and the bottom of the soil sample 33 is in contact with the water; when the research object is gaseous water, a porous plate with the thickness of 2cm and the proper opening rate is selected to be placed on the isolation layer 18 according to the porosity of the soil sample 33, and the maximum height of water supplement is set to be lower than the bottom surface of the soil sample 33, so that the soil sample 33 is not directly contacted with liquid water.
In one embodiment, as shown in fig. 5, the water replenishing unit adjusts the water replenishing height by using a mahalanobis bottle measuring cylinder, and comprises a guide rail 1601 fixed on the outside (back or side) of the oven, wherein the guide rail 1601 is matched with an upper 2 slide blocks 1602 and a lower 2 slide blocks 1602, each slide block 1602 is matched with a hoop 1604, and the mahalanobis bottle measuring cylinder 1603 is clamped by tightening a knob of the hoop 1604. In the water replenishing process, the position of the slider 1602 is adjusted, the wrench is rotated to fix the Ma bottle measuring cylinder 1603 after the Ma bottle measuring cylinder 1603 reaches an ideal height, and then water replenishing is performed. It should be noted that the makroof bottle measuring cylinder 1603, the water replenishing mode and the slider fixing mode are all the prior art, and are not described in detail herein.
In one embodiment, the monitoring system includes a temperature sensor 11, a moisture sensor 2, and a displacement gauge 26. It should be noted that, the utility model discloses a displacement meter 26 and pressure gauge 34 mentioned in are used for measuring the deformation of frozen swelling soil sample respectively and are located with the frozen swelling power, and displacement meter 26 and pressure gauge 34 select according to experimental needs, and both can select one to use, also can use successively.
The temperature sensor 11 is a PT100 thermal resistance type sensor, and has a diameter of 0.4cm and a length of 3 cm; the resistance data can be recorded in real time to reflect the temperature of each layer of the soil sample 33, and the precision can reach +/-0.02 ℃; inserting the reserved first independent hole 10 into the soil sample 33; calibrated at a plurality of standard temperatures before use, and the final measured temperature can be converted by the following formula:
The moisture sensor 2 adopts a Decagon EC-5 small soil moisture sensor with the size of 8.9 multiplied by 1.8 multiplied by 0.7cm, wherein the probe is 5.6cm long, 1.5cm wide and 0.15cm thick; the capacitance data can be recorded in real time to reflect the volume water content of each layer of the soil sample 33, and the precision can reach +/-3% VWC (EC <8 dS/m); the applicable temperature range is-40 to 50 ℃; inserting a second separate hole into the soil sample 33; the device has the advantages of small and simple structure, strong waterproof capability, strong corrosion resistance, high measurement precision, reliable performance, less influence of the salt content of the soil and the like.
One way of mounting the sensor is as follows: before the soil sample 33 is loaded into the inner cylinder 3, a metal embedded part with the size similar to that of the sensor probe can be inserted, and after the compaction work of the soil sample 33 is completed, the embedded part is pulled out and then the sensor is inserted. This mounting includes two benefits: firstly, the secondary disturbance of the compacted soil sample due to the insertion of the sensor is avoided; and secondly, the occurrence of the situation that the sensor is difficult to insert after the soil sample is compacted is prevented, the sensor is protected from being damaged in the inserting process, and the service life is prolonged.
The displacement meter 26 adopts a Keyence IL-065 laser displacement sensor, and the size is 4 multiplied by 2 multiplied by 4 cm; the displacement of incident light on the CMOS can be recorded in real time to reflect the frost heaving amount of the soil sample 33, the repetition precision is 2um, the linearity is +/-0.1% F.S, and the reference distance is 65 mm; the temperature is applied within the range of-10 to 50 ℃ (the temperature can meet most research conditions, and if the temperature does not meet the requirements, a same-grade contact displacement meter can be used; the second screw 132 and the second nut 242 of 2M 3.5 are used to fix to the mounting plate 32 (shown in fig. 4) which is suitable for its size.
Machining the mounting plate 32 to form a first thread 311, and screwing the mounting plate with the first threaded hole 281 through rotation; the assembled sample body is then moved so that the red semiconductor laser light (wavelength 655nm) emitted by the displacement gauge 26 hits the center of the monitoring platform 21 as much as possible.
The monitoring platform 21 is formed with the second thread 312, so that the upper surface of the monitoring platform is smooth and flat, and the risk of measurement error caused by deflection of a foundation is avoided; the second screw hole 282 is screwed by rotation to keep the same displacement as the upper temperature control plate 9.
After the other components are assembled, the displacement meter communication wire 201 is adhered to the top plate 25 by using an adhesive tape, so that the influence on measurement caused by the gravity of the displacement meter communication wire is prevented; the tail end of the device is connected with an external data acquisition instrument through a specific outlet.
The temperature sensor 11, the moisture sensor 2, the displacement meter 26 and the pressure gauge 34 all support data acquisition, and a DT80 data acquisition unit of DataTaker can be connected with a series of sensors through an analog channel, a digital channel, a high-speed counter, a pulse input, a programmable sensor and a serial channel interface to realize simultaneous data acquisition of temperature, voltage, current, resistance, capacitance, an electric bridge and frequency; the problem that normal reading cannot be carried out in the test process is solved, and dynamism is really realized; the man-made workload is greatly reduced; accidental errors caused by manual reading are avoided.
In another embodiment, as shown in fig. 6, this embodiment can achieve the measurement of frozen soil frost heaving force; replacing the monitoring platform 21 with a cylinder, and screwing the monitoring platform into a first threaded hole 281 and a second threaded hole 282 through a first thread 311 and a second thread 312 in a rotating manner, wherein a pressure gauge 34 is arranged between the first threaded hole and the second threaded hole, and a pressure gauge communication wire 202 of the pressure gauge 34 is connected with an external data acquisition instrument through a specific outlet; the assembly mode of other components is the same.
In one embodiment, the frozen soil water vapor migration monitoring device further comprises a supporting mechanism, wherein the supporting mechanism comprises a top cover 8, a base, a top plate 25 and a bottom plate 23.
Be connected with fixed column 27 between bottom plate 23 and the roof 25, the both ends screw thread of fixed column 27 is assisted bottom plate 23 and roof 25 through first nut 241 and is connected, be equipped with the screw hole that is used for connecting displacement meter 26 or pressure gauge 34 on the roof 25, the clear distance of two fixed columns 27 should be greater than the sample body of equipment, and leave certain operating space, its aim at reduces both ends span, the plate body takes place the deflection when avoiding applying load or surveying the frost heaving force, influence the result accuracy.
The top cap 8 is connected at the top of urceolus 5, and the pedestal connection is in the bottom of urceolus 5, is connected with support 4 between top cap 8 and the base, is connected with supporting legs 15 between base and the bottom plate 23, and with the sample body whole aerial certain height on bottom plate 23, reserve the return bend space of lower part cold bath hose 1 and aqueduct, avoid leading to blockking up owing to roll over a pipe.
In order to avoid the extension of each pipe body, the structure of the top cover 8 and the base is respectively provided with a first circular ring 14 and a second circular ring 7, and the first circular ring 14 and the second circular ring 7 are fixedly overlapped.
Threaded holes comprising 4 supporting feet 15, 4 brackets 4 and 4 first screws 131 are reserved on the first circular ring 14, and the hollow inner circle of the first circular ring 14 is used as an extension channel of the cold bath hose 1 and the aqueduct; and in order to place the lower temperature control disk 6, the inner diameter of the first ring 14 is smaller than the diameter of the lower temperature control disk 6.
The second ring 7 is fixed to the first ring 14 by 4 first screws 131; the inner circle radius of the first circular ring 14 is smaller than that of the second circular ring 7, so that after the first circular ring 14 and the second circular ring 7 are overlapped and fixed, the inner diameters of the two are different to form a groove 19; the outer cylinder 5 is placed in the groove 19, the end surface of the outer cylinder 5 is abutted against the first circular ring 14, and the side wall of the outer cylinder 5 is limited by the second circular ring 7. The groove 19 limits the horizontal displacement of the outer cylinder 5 and the lower temperature control plate 6, and an O-shaped sealing ring is arranged between the grooves to ensure the sealing performance of the equipment. The O-shaped sealing ring is made of a silica gel material and mainly plays a role in sealing and seepage prevention; the sealing performance of the lower structure is the premise of ensuring the accuracy of water supplementing data, and if the water supplementing data does not reach the expectation, glass cement can be supplemented for sealing; the glass cement has good sealing and low temperature resistance, and is convenient to disassemble and process.
The top cover 8 and the base are assembled to be convenient for adapting to soil samples with different sizes, and only the second circular rings 7 with different inner diameters need to be replaced during the period.
Base and top cap 8 link to each other through 4 supports 4, and urceolus 5 is inlayed in two upper and lower recesses, and its vertical displacement also suffers the restriction after the connection is accomplished, nevertheless does not have any influence to urceolus 3, accords with experimental expectation. In order to improve the heat insulation effect on the sample cylinder, the outer side of the bracket 4 can be wrapped with heat insulation cotton 22.
Factors that affect soil frost heaving include: soil texture, moisture, temperature, load, structure; the utility model discloses all can adjust and test above-mentioned factor, more crucial is the test method who has introduced frozen soil gaseous state water migration and has solved the problem that the last temperature control dish freezes unable removal with the sample section of thick bamboo.
The utility model discloses a frozen soil steam migration monitoring devices's an embodiment operation flow as follows:
1. the assembly connection comprises an inner cylinder, an outer cylinder, an upper temperature control disc, a lower temperature control disc, a base, a temperature sensor, a moisture sensor, a laser displacement meter, a data acquisition instrument, a cold bath hose and the like.
2. And carrying out no-load test according to the test scheme, measuring the compensation temperature between the measured temperature and the set temperature, adjusting the temperature control equation, and accurately controlling the test temperature.
3. Placing the soil sample in an oven for drying, uniformly stirring the soil sample and water according to the water content required by the test scheme, and then placing the soil sample and the water in a moisturizing vessel for standing for 24 hours to uniformly distribute the water; and then, filling the soil sample into an inner glass cylinder of which the inner wall is coated with vaseline for lubrication in a layered manner, and carrying out five-layer compaction forming according to the calculated compaction degree to obtain the expected soil sample.
4. Inserting a temperature sensor and a moisture sensor into the soil body; sealing some open parts with sealant according to requirements; and wrapping a plurality of circles of heat-insulating cotton outside the sample outer cylinder.
5. Installing a laser displacement meter to enable the laser spot beam to be opposite to the center of the position measuring platform; fixing a Mariotte bottle measuring cylinder to enable the water supplementing height to reach the expectation, and recording; and closing the working window.
6. Setting temperature control parameters and a digital acquisition mode at a computer end; and after the test period is reached, exporting data, and carrying out drawing analysis.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. The frozen soil water vapor migration monitoring device is characterized by comprising a sample body, a temperature and humidity regulating and controlling mechanism and a monitoring mechanism;
the sample body comprises a soil sample, an inner cylinder for placing the soil sample, an outer cylinder sleeved on the outer side of the inner cylinder and heat insulation cotton wrapped on the periphery of the outer cylinder;
the temperature and humidity regulating mechanism comprises an upper temperature control disc, a lower temperature control disc and a water supplementing unit, the upper temperature control disc is placed in the inner cylinder and covers the upper part of the soil sample, the lower temperature control disc is placed in the outer cylinder, an isolation layer is reserved between the lower temperature control disc and the bottom of the soil sample, and the water supplementing unit comprises a water guide pipe and is connected to the isolation layer through the water guide pipe;
monitoring mechanism includes temperature sensor, moisture sensor, displacement meter and pressure gauge, temperature sensor and moisture sensor run through the lateral wall of inner tube and urceolus and extend to soil sample inside, displacement meter and pressure gauge are installed in soil sample top.
2. The frozen soil water vapor migration monitoring device according to claim 1, wherein the side walls of the inner barrel and the outer barrel are provided with mounting holes arranged in pairs, each pair of mounting holes comprises a plurality of independent holes formed in the side wall of the inner barrel and a strip-shaped hole formed in the side wall of the outer barrel, the strip-shaped hole is adapted to the arrangement path of the independent holes, and the temperature sensor or the moisture sensor extends into the soil sample after penetrating through the independent holes and the strip-shaped hole in the use state.
3. The frozen soil water vapor migration monitoring device according to claim 2, wherein the inner cylinder and the outer cylinder are both cylinders with openings at both ends and hollow interiors, the plurality of independent holes in each pair of mounting holes are arranged along the height direction of the cylinders, the strip-shaped holes extend along the height direction of the cylinders, and the total length of the extension of the strip-shaped holes is greater than the total length of the arrangement of the plurality of independent holes.
4. The frozen soil water vapor migration monitoring device according to claim 3, wherein the inner diameter of the outer cylinder is 2-3 mm larger than the outer diameter of the inner cylinder.
5. The frozen soil water vapor migration monitoring device according to claim 1, wherein the side wall of the upper temperature control plate is attached to the inner wall of the inner barrel, the upper temperature control plate comprises a first upper plate and a first lower plate which are fixedly stacked, a coil pipe is installed at the stacking position of the first upper plate and the first lower plate, the coil pipe is connected with a cold bath hose, a threaded hole is formed in the first upper plate, the threaded hole is connected with a monitoring platform, and the mounting position of the displacement meter or the pressure meter is matched with the monitoring platform.
6. The frozen soil water vapor migration monitoring device according to claim 1, wherein the side wall of the lower temperature control plate is attached to the inner wall of the outer cylinder, the lower temperature control plate comprises a second upper plate and a second lower plate which are fixedly stacked, a coil pipe is installed at the stacked part of the second upper plate and the second lower plate, the coil pipe is connected with a cold bath hose, and water replenishing channels for avoiding the water guide pipe are arranged on the second upper plate and the second lower plate.
7. The frozen soil water vapor migration monitoring device of claim 1, wherein the thickness of the isolation layer is 2 cm.
8. The frozen soil water vapor migration monitoring device of claim 1, wherein a permeable stone or a porous plate is placed in the isolation layer.
9. The frozen soil water vapor migration monitoring device according to claim 1, further comprising a support mechanism, the support mechanism comprising a top cover, a base, a top plate and a bottom plate;
the top cap is connected the top of urceolus, the base is connected the bottom of urceolus, be connected with the support between top cap and the base, top cap and base all include first ring and second ring, the interior circle radius of first ring is less than the interior circle radius of second ring, the terminal surface and the first ring of urceolus offset, just the lateral wall of urceolus is subject to the second ring.
10. The frozen soil water vapor migration monitoring device according to claim 9, wherein the top plate and the bottom plate are both flat plates, the bottom plate is connected with the top plate through a fixing column, a supporting leg is connected between the first ring and the bottom plate, and the top plate is provided with a threaded hole for connecting a displacement meter or a pressure meter.
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| CN201920407496.2U CN210154987U (en) | 2019-03-28 | 2019-03-28 | Frozen soil water vapor migration monitoring devices |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110031367A (en) * | 2019-03-28 | 2019-07-19 | 绍兴文理学院元培学院 | A kind of frozen soil steam migration monitoring device |
| CN112082852A (en) * | 2020-11-13 | 2020-12-15 | 中南大学 | Unsaturated triaxial apparatus |
| CN114076727A (en) * | 2022-01-10 | 2022-02-22 | 中国空气动力研究与发展中心低速空气动力研究所 | Resistivity-based ice porosity measurement method |
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2019
- 2019-03-28 CN CN201920407496.2U patent/CN210154987U/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110031367A (en) * | 2019-03-28 | 2019-07-19 | 绍兴文理学院元培学院 | A kind of frozen soil steam migration monitoring device |
| CN112082852A (en) * | 2020-11-13 | 2020-12-15 | 中南大学 | Unsaturated triaxial apparatus |
| CN112082852B (en) * | 2020-11-13 | 2021-02-02 | 中南大学 | Unsaturated triaxial apparatus |
| CN114076727A (en) * | 2022-01-10 | 2022-02-22 | 中国空气动力研究与发展中心低速空气动力研究所 | Resistivity-based ice porosity measurement method |
| CN114076727B (en) * | 2022-01-10 | 2022-05-13 | 中国空气动力研究与发展中心低速空气动力研究所 | Resistivity-based ice porosity measurement method |
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