CN108037270B - Quick freezing and preserving device for soil microstructure test sample - Google Patents
Quick freezing and preserving device for soil microstructure test sample Download PDFInfo
- Publication number
- CN108037270B CN108037270B CN201711404856.5A CN201711404856A CN108037270B CN 108037270 B CN108037270 B CN 108037270B CN 201711404856 A CN201711404856 A CN 201711404856A CN 108037270 B CN108037270 B CN 108037270B
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- pressing
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- 238000007710 freezing Methods 0.000 title claims abstract description 101
- 230000008014 freezing Effects 0.000 title claims abstract description 101
- 239000002689 soil Substances 0.000 title claims abstract description 89
- 238000003825 pressing Methods 0.000 claims abstract description 83
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 76
- 239000007788 liquid Substances 0.000 claims abstract description 66
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 38
- 239000007787 solid Substances 0.000 claims abstract description 23
- 230000001502 supplementing effect Effects 0.000 claims abstract description 15
- 238000005192 partition Methods 0.000 claims description 15
- 238000009423 ventilation Methods 0.000 claims description 11
- 238000002347 injection Methods 0.000 claims description 10
- 239000007924 injection Substances 0.000 claims description 10
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 claims description 7
- 229910052753 mercury Inorganic materials 0.000 claims description 7
- 239000003566 sealing material Substances 0.000 claims description 7
- -1 polytetrafluoroethylene Polymers 0.000 claims description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 5
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 5
- 238000000034 method Methods 0.000 abstract description 24
- QWTDNUCVQCZILF-UHFFFAOYSA-N isopentane Chemical compound CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 abstract description 16
- AFABGHUZZDYHJO-UHFFFAOYSA-N dimethyl butane Natural products CCCC(C)C AFABGHUZZDYHJO-UHFFFAOYSA-N 0.000 abstract description 8
- 230000006378 damage Effects 0.000 abstract description 6
- 238000002844 melting Methods 0.000 abstract description 2
- 230000008018 melting Effects 0.000 abstract description 2
- 239000011148 porous material Substances 0.000 description 11
- 229910000365 copper sulfate Inorganic materials 0.000 description 4
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000001035 drying Methods 0.000 description 3
- 238000004108 freeze drying Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 239000002274 desiccant Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000007774 longterm Effects 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- 238000009777 vacuum freeze-drying Methods 0.000 description 2
- 238000007605 air drying Methods 0.000 description 1
- 230000006399 behavior Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 210000005239 tubule Anatomy 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L7/00—Heating or cooling apparatus; Heat insulating devices
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/42—Low-temperature sample treatment, e.g. cryofixation
Abstract
The invention discloses a rapid freezing and preserving device for a soil microstructure test sample, which consists of a freezing tank, a bracket, a liquid nitrogen supplementing tank, a mercury-pressing sample tray, an electron microscope sample tray, a liquid tray and a solid tray; the bracket is arranged in the freezing tank, the liquid nitrogen supplementing tank is connected with the freezing tank, and the mercury-pressing sample tray, the electron microscope sample tray, the liquid tray and the solid tray are arranged on the bracket; the invention realizes the control of freezing temperature through the temperature controller and the liquid nitrogen supplementing tank, and avoids microstructure damage caused by liquid volume expansion in the soil sample due to insufficient temperature; by using isopentane, a frozen shell is prevented from being formed on the surface of the soil sample in the freezing process, so that the soil sample is quickly and uniformly frozen; the contact of people and the soil sample is effectively avoided, the microstructure of the soil sample is protected from being influenced, the time required for moving the soil sample from the freezing tank to the vacuum freeze dryer is greatly shortened, and the microstructure damage caused by liquid melting in the soil sample is avoided.
Description
Technical Field
The invention relates to the technical field of soil microstructure research, in particular to a rapid freezing and storing device for a soil microstructure test sample.
Background
The engineering property of the soil is mainly controlled by the microstructure of the soil from the essence, and researches prove that the macroscopic behaviors of the soil, such as strength, frost heaving and the like, can be explained through the microstructure characteristics, so that the method has very important significance for researching the microstructure of the soil. At present, the test of the microstructure of the soil body is mainly carried out by a scanning electron microscope and a mercury porosimeter. When the scanning electron microscope and the mercury-pressing sample are prepared, the freeze-drying method is mostly adopted, namely, the soil sample is quickly frozen by utilizing liquid nitrogen, so that liquid in soil is changed into amorphous ice without volume expansion, and then the amorphous ice in the soil sample is sublimated by utilizing a vacuum freeze-drying instrument, thereby achieving the purpose of drying the soil sample without damaging the structure of the soil sample. The advantages of this approach are two: firstly, the microstructure damage caused by the shrinkage of the soil sample due to an air drying method, a drying method and the like can be avoided; and secondly, the liquid is changed into ice without volume expansion by quick freezing, and the microstructure of the soil sample cannot be damaged due to the volume expansion of the liquid.
The existing method for quickly freezing the soil sample is to put the soil sample into a prepared net bag and then put the net bag into a liquid nitrogen tank, and has certain defects. On the one hand, when more soil samples are placed in a liquid nitrogen tank at one time, the temperature change in the tank is larger, and the ultra-low temperature required by rapid freezing cannot be necessarily achieved; on the other hand, after the soil sample with higher water content is put into the net bag, the middle part of the soil sample is bent and deformed due to the stress at the two ends of the soil sample, and the microstructure is destroyed, and the deformation of the scanning electron microscope sample is particularly serious because the scanning electron microscope sample is in a long strip shape. In addition, the existing method needs to manually move the soil sample in a plurality of links, which not only affects the microstructure of the soil sample, but also takes out the net bag filled with the soil sample from the liquid nitrogen tank, and the process of putting the net bag into the vacuum freeze dryer is very time-consuming, and part of ice in the soil sample is gradually melted in the time.
Disclosure of Invention
The invention aims to solve the problems that the ultra-low temperature required by the rapid freezing cannot be realized when the soil microstructure research is carried out, the microstructure of a soil sample is influenced due to manual movement or the research result is influenced due to time-consuming operation process, and the like.
A rapid freezing and preserving device for a soil microstructure test sample consists of a freezing tank, a bracket, a liquid nitrogen supplementing tank, a mercury-pressing sample tray, an electron microscope sample tray, a liquid tray and a solid tray;
the bracket is arranged in the freezing tank, the liquid nitrogen supplementing tank is connected with the freezing tank, the mercury-pressing sample tray, the electron microscope sample tray, the liquid tray and the solid tray are arranged on the bracket, and the liquid tray and the solid tray are the same structural body;
the freezing tank comprises a freezing tank upper part, a freezing tank lower part and a temperature control device, wherein the temperature control device is arranged on the freezing tank, the freezing tank upper part is arranged on the freezing tank lower part, and the freezing tank lower part comprises threads;
the temperature control device is provided with a temperature setting device, a plurality of temperature sensors, a ventilation valve and a nitrogen injection valve, and the temperature setting device, the plurality of temperature sensors, the ventilation valve and the nitrogen injection valve are respectively arranged on the freezing tank;
the bracket comprises a rotary valve, a rotary shaft and a plurality of sample loading discs, the rotary valve is arranged at the upper end of the rotary shaft, and the sample loading discs are connected with the rotary shaft;
the liquid nitrogen supplementing tank comprises a tank body, a base and a thin pipe, wherein the tank body is arranged on the base, one end of the thin pipe is introduced into the tank body through the base, and the other end of the thin pipe is connected with the freezing tank and is embedded into a whole through threads;
the mercury-pressing sample tray comprises a mercury-pressing tray cover and a mercury-pressing tray body, wherein the mercury-pressing tray cover is arranged on the mercury-pressing tray body;
the mercury-pressing tray body is provided with a first upper thread, a first lower thread and a first bottom plate, the first bottom plate is arranged in the middle of the mercury-pressing tray body, and a first vent hole, a first supporting rod, a first locking device and a first partition plate are arranged on the first bottom plate;
the mercury-pressing tray cover is embedded with the mercury-pressing tray body through a first upper thread;
the electron microscope sample disk comprises an electron microscope disk cover and an electron microscope disk body, wherein the electron microscope disk cover is arranged on the electron microscope disk body;
the second bottom plate is arranged in the middle of the electric mirror disc body, and is provided with a second ventilation hole, a second supporting rod, a second locking device and a second partition plate;
the electric mirror disc cover is embedded with the electric mirror disc body through a second upper thread;
the liquid disc comprises a first disc cover and a first disc body, the first disc cover is arranged on the first disc body, and the first disc cover is embedded with the first disc body through threads;
the solid disc comprises a second disc cover and a second disc body, the second disc cover is arranged on the second disc body, and the second disc cover is embedded with the second disc body through threads;
the joint of the tubule and the thread is coated with a sealing material;
the sealing material is polytetrafluoroethylene;
the mercury-pressing sample disk, the electron microscope sample disk, the liquid disk and the solid disk are detachable;
the first partition plate and the second partition plate can move up and down;
the sealing material is polytetrafluoroethylene.
The working principle and the process of the invention are as follows:
when the device is used, the first locking device on the mercury-pressing sample tray is firstly opened, the first partition plate is enabled to be lowered to be in contact with the first supporting rod, the mercury-pressing samples are placed in sample grids in the mercury-pressing sample tray, each mercury-pressing sample tray can contain a soil sample, the first partition plate is pushed upwards, the first partition plate is fixed by the first locking device, the mercury-pressing tray cover is covered and screwed tightly, isopentane is injected into the liquid tray, the liquid tray is embedded with the liquid tray through the first lower thread of the mercury-pressing sample tray, the combined whole is placed in the sample tray on the support, the support can be used for simultaneously placing the mercury-pressing sample tray, a large amount of bubbles and gas films are generated on the surface layer of the soil sample during direct freezing to form a frozen shell, the soil sample is wrapped, the soil sample is prevented from being further cooled, the isopentane is placed at the lower part of the soil sample, the isopentane plays a role of transitional liquid in the freezing process, and the liquid nitrogen enables the liquid to rapidly reach the freezing point (- °c) under the environment, and the phenomenon can not occur uniformly and the phenomenon can occur on the freezing point rapidly;
after liquid nitrogen is injected into the freezing tank, the upper temperature of the freezing tank is higher than the temperature of the bottom, the temperature measured by the temperature sensor is higher than the temperature of the height of the uppermost sample tray of the bracket, so that the upper temperature is controlled to be at the temperature required by quick freezing by utilizing the temperature control device, quick freezing of a soil sample can be ensured, the temperature control device on the freezing tank is opened, the temperature value is set to be minus DEG C through the temperature setting device, at the moment, if the temperatures measured by the two temperature sensors in the freezing tank are higher than minus DEG C, the ventilation valve and the nitrogen injection valve are simultaneously opened, liquid nitrogen in the tank body of the liquid nitrogen supplementing tank is injected into the freezing tank, when the temperature measured by any one of the two temperature sensors is equal to or lower than minus DEG C, the ventilation valve and the nitrogen injection valve are closed, the freezing tank is divided into the upper part and the lower part of the freezing tank, and the upper part and the lower part of the freezing tank, once the condition occurs, the tank body can be unscrewed, and the falling object can be taken out;
after the temperature in the freezing tank is stable, placing a bracket containing the mercury-pressing sample tray into the freezing tank, wherein the top cover of the bracket is slightly larger than the tank opening of the freezing tank, so that the bracket can be hung at the tank opening, rotating a rotating valve at the top of the bracket to enable the sample tray to rotate along with a rotating shaft, fully contacting the mercury-pressing sample tray on the sample tray with liquid nitrogen at the moment, rapidly cooling, rotating the rotating valve after freezing is finished to enable the sample tray to be folded, and then lifting the bracket out of the freezing tank; taking out the mercury-pressing sample tray, firstly taking down the liquid tray, then opening the mercury-pressing tray cover, putting the mercury-pressing tray body into a precooled vacuum freeze-drying instrument, taking out the mercury-pressing tray body after freeze-drying, covering the mercury-pressing tray cover and screwing, adding anhydrous copper sulfate into the solid tray, embedding the solid tray and the mercury-pressing sample tray through a first lower thread, wherein the anhydrous copper sulfate is used as a drying agent to prevent soil samples in the mercury-pressing sample tray from absorbing moisture in the air, and embedding the mercury-pressing tray body, the mercury-pressing tray cover and the solid tray through threads, so that the mercury-pressing tray body has better sealing property, and the combination is suitable for long-term storage of the freeze-dried microstructure samples.
The invention has the beneficial effects that:
1. the freezing temperature is controlled through the temperature controller and the liquid nitrogen supplementing tank, so that microstructure damage caused by liquid volume expansion in the soil sample due to insufficient temperature is avoided;
2. by using isopentane, a frozen shell is prevented from being formed on the surface of the soil sample in the freezing process, so that the soil sample is quickly and uniformly frozen;
3. in the whole process of freezing, drying and preserving the freeze-dried sample, the contact between a person and the soil sample is effectively avoided, and the microstructure of the soil sample is protected from being influenced;
4. by using the electron microscope sample tray and the mercury-pressing sample tray, the time required for moving the soil sample from the freezing tank to the vacuum freeze dryer is greatly shortened, and the microstructure damage caused by liquid melting in the soil sample is avoided.
Drawings
FIG. 1 is a schematic representation of the percentage of pores of different pore diameters within each soil sample according to the present invention.
FIG. 2 is a schematic view of a frozen electron microscope of the present invention.
FIG. 3 is a schematic diagram of an electron microscope sample frozen by the prior art method.
Fig. 4 is a schematic diagram of the assembly of the freezing tank, the liquid nitrogen replenishing tank and the bracket of the invention.
Fig. 5 is a schematic view of a mercury-filled sample tray of the present invention.
Fig. 6 is a schematic view of a mercury-pressing liquid tray of the present invention.
FIG. 7 is a schematic view of an electron microscope sample tray of the present invention.
Fig. 8 is a schematic view of an electron microscope liquid tray of the present invention.
Fig. 9 is a schematic view of a liquid tray of the present invention.
Detailed Description
Referring to fig. 1-9, a rapid freezing and preserving device for a soil microstructure test sample is composed of a freezing tank 1, a bracket 2, a liquid nitrogen supplementing tank 3, a mercury-pressing sample tray 4, an electron microscope sample tray 5, a liquid tray 6 and a solid tray 7;
the bracket 2 is arranged in the freezing tank 1, the liquid nitrogen supplementing tank 3 is connected with the freezing tank 1, the mercury-pressing sample tray 4, the electron microscope sample tray 5, the liquid tray 6 and the solid tray 7 are arranged on the bracket 2, and the liquid tray 6 and the solid tray 7 are the same structural body;
the freezing tank 1 comprises an upper freezing tank 11, a lower freezing tank 12 and a temperature control device 13, wherein the temperature control device 13 is arranged on the upper freezing tank 11, the upper freezing tank 11 is arranged on the lower freezing tank 12, and the lower freezing tank 12 comprises threads 121;
the temperature control device 13 has a temperature setting device 131, a plurality of temperature sensors 132, a vent valve 133 and a nitrogen injection valve 134, and the temperature setting device 131, the plurality of temperature sensors 132, the vent valve 133 and the nitrogen injection valve 134 are respectively arranged on the freezing tank 11;
the bracket 2 comprises a rotary valve 21, a rotary shaft 22 and a plurality of sample loading discs 23, wherein the rotary valve 21 is arranged at the upper end of the rotary shaft 22, and the sample loading discs 23 are connected with the rotary shaft 22;
the liquid nitrogen supplementing tank 3 comprises a tank body 31, a base 32 and a thin tube 33, wherein the tank body 31 is arranged on the base 32, one end of the thin tube 33 is introduced into the tank body 31 through the base 32, and the other end of the thin tube 33 is connected with the freezing tank 1 and is embedded into a whole through a thread 121;
the mercury-pressing sample tray 4 comprises a mercury-pressing tray cover 41 and a mercury-pressing tray body 42, and the mercury-pressing tray cover 41 is arranged on the mercury-pressing tray body 42;
the mercury-pressing tray 42 is provided with a first upper thread 421, a first lower thread 422 and a first bottom plate 423, the first bottom plate 423 is arranged in the middle of the mercury-pressing tray 42, and the first bottom plate 423 is provided with a first vent hole 424, a first supporting rod 425, a first locking device 426 and a first partition 427;
the mercury-pressing tray cover 41 is engaged with the mercury-pressing tray body 42 by the first upper screw 421;
the electron microscope sample disk 5 includes an electron microscope disk cover 51 and an electron microscope disk body 52, the electron microscope disk cover 51 is arranged on the electron microscope disk body 52;
the electronic mirror plate 52 has a second upper thread 521, a second lower thread 522, and a second bottom plate 523, the second bottom plate 523 is disposed in the middle of the electronic mirror plate 52, and the second bottom plate 523 is provided with a second ventilation hole 524, a second supporting rod 525, a second locking device 526, and a second partition 527;
the electronic mirror plate cover 51 is embedded with the electronic mirror plate body 52 through a second upper thread 521;
the liquid tray 6 includes a first tray cover 61 and a first tray body 62, the first tray cover 61 is provided on the first tray body 62, and the first tray cover 61 is engaged with the first tray body 62 by screw threads;
the solid tray 7 includes a second tray cover 71 and a second tray body 72, the second tray cover 71 is provided on the second tray body 72, and the second tray cover 71 is engaged with the second tray body 72 by screw threads;
the joint of the slim tube 33 and the screw thread 121 is coated with sealing material (polytetrafluoroethylene);
the mercury-pressing sample disk 4, the electron microscope sample disk 5, the liquid disk 6 and the solid disk 7 are detachable;
the first diaphragm 427 and the second diaphragm 527 are movable up and down.
The working principle and the process of the invention are as follows:
referring to fig. 1-9, since the quick freezing method of the electron microscope sample and the mercury-pressing sample are the same, only the difference is made between the used devices, namely, the mercury-pressing sample is loaded in the mercury-pressing sample tray 4 and the electron microscope sample is loaded in the electron microscope sample tray 5, so the quick freezing process of the mercury-pressing sample is selected to illustrate the working principle and process of the invention.
When the device is used, the first locking device 426 on the mercury-pressing sample tray 4 is firstly opened, the first partition plate 427 is lowered to be in contact with the first supporting rod 425, the mercury-pressing sample is placed in sample grids in the mercury-pressing sample tray 4, each mercury-pressing sample tray 4 can contain 9 soil samples, the first partition plate 427 is pushed upwards, the first partition plate 427 is fixed by the first locking device 426, the mercury-pressing tray cover 41 is covered and screwed, isopentane is injected into the liquid tray 6, the liquid tray 6 is embedded together with the first lower thread 422 of the mercury-pressing sample tray 4, the combined whole is placed in the sample tray 23 on the bracket 2, 5 mercury-pressing sample trays 4 can be placed at the same time, and due to the large temperature difference between the soil samples and liquid nitrogen, a large amount of bubbles and gas films can be generated on the surface layer of the soil samples during direct freezing, so as to form a frozen shell, the further cooling of the soil samples is blocked, the isopentane is placed on the lower part of the soil samples, the isopentane can avoid the phenomenon, the phenomenon can be rapidly performed in the transient liquid in the process (-140 ℃ when the freezing condition is not uniform in the rapid freezing condition;
after liquid nitrogen is injected into the freezing tank 1, the upper temperature is higher than the bottom temperature, the temperature measured by the temperature sensor 132 is the temperature of the height of the uppermost sample tray 23 of the bracket 2, so that the temperature required by quick freezing can be ensured by controlling the upper temperature by the temperature control device 13, quick freezing of soil samples can be ensured, the temperature control device 13 on the freezing tank 1 is opened, the temperature value is set to be 170 ℃ below zero by the temperature setting device 131, at this time, if the temperatures measured by the two temperature sensors 132 in the freezing tank 1 are higher than 170 ℃, the ventilation valve 133 and the nitrogen injection valve 134 are simultaneously opened, liquid nitrogen in the tank body 31 of the liquid nitrogen supplementing tank 3 is injected into the freezing tank 1, when the temperature measured by any one of the two temperature sensors 132 is equal to or lower than 170 ℃, the ventilation valve 133 and the nitrogen injection valve 134 are closed, the freezing tank 1 is divided into an upper part 11 of the freezing tank and a lower part of the freezing tank 12, in order to prevent objects from entering the tank and can not be taken out, and once the situation occurs, the tank body can be taken out;
after the temperature in the freezing tank 1 is stable, the bracket 2 containing the mercury-pressing sample trays 4 is placed in the freezing tank 1, the top cover of the bracket 2 is slightly larger than the tank opening of the freezing tank 1, so the bracket 2 can be hung at the tank opening, the rotary valve 21 at the top of the bracket is rotated, the sample trays 23 with the numbers 1, 3 and 5 are rotated 180 degrees along with the rotary shaft 22, and the mercury-pressing sample trays 4 on the sample trays 23 are fully contacted with liquid nitrogen at the moment, so that the temperature can be reduced rapidly. After the freezing is finished, rotating the rotary valve 21 to fold the sample trays 1, 3 and 5, and then lifting the bracket 2 out of the freezing tank 1; taking out the mercury-pressing sample tray 4, firstly taking down the liquid tray 6, then opening the mercury-pressing tray cover 41, putting the mercury-pressing tray body 42 into a pre-cooled vacuum freeze dryer, taking out the mercury-pressing tray body 42 after freeze-drying, covering the mercury-pressing tray cover 41 and screwing, adding anhydrous copper sulfate into the solid tray 7, embedding the solid tray 7 and the mercury-pressing sample tray 4 through the first lower screw thread 422, wherein the anhydrous copper sulfate is used as a drying agent to prevent soil samples in the mercury-pressing sample tray 4 from absorbing moisture in the air, and the mercury-pressing tray body 42, the mercury-pressing tray cover 41 and the solid tray 7 are embedded through screw threads, so that the combination is suitable for long-term preservation of the freeze-dried microstructure samples;
respectively carrying out mercury-pressing tests on the rapidly frozen soil sample and the soil sample frozen by the prior method to obtain the content of each pore diameter pore space of the soil sample and the porosity of the soil sample, and carrying out two samples for each group of tests to avoid errors caused by accidental factors, namely, freezing the 1 st and 2 nd soil samples by the method, freezing the 3 rd and 4 th soil samples by the prior method, and measuring the porosity of the soil sample by a macroscopic test, wherein the soil samples used in the tests are loess from Jingyang county of Shaanxi, and the soil samples are the same;
as can be seen from FIG. 1, the pore diameters of the components of the No. 1 and No. 2 soil samples and the No. 3 and No. 4 soil samples are not different, so that the reliability of the test data is higher. It can be seen that the macropore content of the No. 3 and No. 4 soil samples is obviously higher than that of the No. 1 and No. 2 soil samples, and the pore content of the pore diameters of 0.01-0.1 μm and 0.1-1 μm is obviously lower than that of the No. 1 and No. 2 soil samples, which indicates that the prior rapid freezing soil sample method leads to the destruction of smaller pores, and adjacent smaller pores are communicated to form macropores, so that the measured smaller pore content is lower and the macropore content is higher, which can be considered to be caused by the disturbance of the soil sample structure in the original sample preparation process;
table 1 shows the porosity of the soil samples measured by the macroscopic test and each mercury intrusion test, and it can be seen that the porosity of the No. 1 and No. 2 soil samples is slightly different from the porosity obtained by the macroscopic test, and the porosity of the No. 3 and No. 4 soil samples is slightly higher. This is because the internal structure of the soil sample is destroyed, resulting in an increase in the total amount of pores, while the total volume of the soil sample remains unchanged, so that the porosity is improved, which also verifies the conclusion obtained by the mercury intrusion test described above.
TABLE 1
As can be seen from the analysis of the above Table 1, compared with the existing method for rapidly freezing the soil sample, the method has the advantages that the microstructure of the soil sample is not damaged, and the measured data is more accurate;
the electron microscope soil sample is taken from dredger fill in new coastal area of Tianjin, the plastic limit water content is 20.5%, the liquid limit water content is 37.7%, the water content of the soil sample used this time is 34.6%, it can be seen that the frozen soil sample does not deform, the middle part of the frozen soil sample is bent, and the structure of the frozen soil sample is destroyed.
Claims (1)
1. A quick freezing and preserving device of soil microstructure test sample, its characterized in that: consists of a freezing tank (1), a bracket (2), a liquid nitrogen supplementing tank (3), a mercury-pressing sample disk (4), an electron microscope sample disk (5), a liquid disk (6) and a solid disk (7);
the bracket (2) is arranged in the freezing tank (1), the liquid nitrogen supplementing tank (3) is connected with the freezing tank (1), the mercury-pressing sample tray (4), the electron microscope sample tray (5), the liquid tray (6) and the solid tray (7) are arranged on the bracket (2), and the liquid tray (6) and the solid tray (7) are of the same structure;
the freezing tank (1) comprises a freezing tank upper part (11), a freezing tank lower part (12) and a temperature control device (13), wherein the temperature control device (13) is arranged on the freezing tank upper part (11), the freezing tank upper part (11) is arranged on the freezing tank lower part (12), and the freezing tank lower part (12) comprises threads (121); the temperature control device (13) is provided with a temperature setting device (131), a plurality of temperature sensors (132), a ventilation valve (133) and a nitrogen injection valve (134), wherein the temperature setting device (131), the plurality of temperature sensors (132), the ventilation valve (133) and the nitrogen injection valve (134) are respectively arranged on the freezing tank (11);
the bracket (2) comprises a rotary valve (21), a rotary shaft (22) and a plurality of sample loading discs (23), wherein the rotary valve (21) is arranged at the upper end of the rotary shaft (22), and the sample loading discs (23) are connected with the rotary shaft (22);
the liquid nitrogen supplementing tank (3) comprises a tank body (31), a base (32) and a thin tube (33), wherein the tank body (31) is arranged on the base (32), one end of the thin tube (33) is introduced into the tank body (31) through the base (32), and the other end of the thin tube (33) is connected with the freezing tank (1) and is embedded into the freezing tank into a whole through a thread (121);
the mercury-pressing sample tray (4) comprises a mercury-pressing tray cover (41) and a mercury-pressing tray body (42), wherein the mercury-pressing tray cover (41) is arranged on the mercury-pressing tray body (42);
the mercury-pressing disk body (42) is provided with a first upper thread (421), a first lower thread (422) and a first bottom plate (423), the first bottom plate (423) is arranged in the middle of the mercury-pressing disk body (42), and the first bottom plate (423) is provided with a first vent hole (424), a first supporting rod (425), a first locking device (426) and a first partition plate (427);
the mercury-pressing disc cover (41) is embedded with the mercury-pressing disc body (42) through a first upper thread (421);
opening a first locking device (426) on the mercury-filled sample tray (4) to enable the first partition plate (427) to descend to be in contact with the first supporting rod (425), and then placing the mercury-filled sample into a sample cell in the mercury-filled sample tray (4);
the electron microscope sample disk (5) comprises an electron microscope disk cover (51) and an electron microscope disk body (52), wherein the electron microscope disk cover (51) is arranged on the electron microscope disk body (52); the electronic mirror disc body (52) is provided with a second upper thread (521), a second lower thread (522) and a second bottom plate (523), the second bottom plate (523) is arranged in the middle of the electronic mirror disc body (52), and the second bottom plate (523) is provided with a second ventilation hole (524), a second supporting rod (525), a second locking device (526) and a second partition plate (527);
the electronic mirror disc cover (51) is embedded with the electronic mirror disc body (52) through a second upper thread (521);
the liquid disc (6) comprises a first disc cover (61) and a first disc body (62), the first disc cover (61) is arranged on the first disc body (62), and the first disc cover (61) is in threaded fit with the first disc body (62);
the solid disc (7) comprises a second disc cover (71) and a second disc body (72), the second disc cover (71) is arranged on the second disc body (72), and the second disc cover (71) is in threaded fit with the second disc body (72);
the joint of the thin tube (33) and the thread (121) is coated with a sealing material;
the sealing material is polytetrafluoroethylene; the mercury-pressing sample disk (4), the electron microscope sample disk (5), the liquid disk (6) and the solid disk (7) are detachable; the first baffle (427) and the second baffle (527) can move up and down;
the sealing material is polytetrafluoroethylene.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
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