CN115753873A - Frozen soil body water migration and frost heaving rule testing device and testing method - Google Patents
Frozen soil body water migration and frost heaving rule testing device and testing method Download PDFInfo
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- CN115753873A CN115753873A CN202211422639.XA CN202211422639A CN115753873A CN 115753873 A CN115753873 A CN 115753873A CN 202211422639 A CN202211422639 A CN 202211422639A CN 115753873 A CN115753873 A CN 115753873A
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Abstract
The invention discloses a frozen soil moisture migration and frost heaving rule testing device and a testing method, belongs to the technical field of indoor geotechnical low-temperature tests, and solves the problems that the real occurrence environment of a soil body is ignored in the existing freezing test, and the influence of the injection of a soil body modifier on the moisture migration and frost heaving rule in the freezing process of the improved soil body is not considered; the device comprises a sample simulation device, wherein the sample simulation device is arranged in a loading device, the loading device is used for carrying out ground stress simulation loading on a soil body sample in the sample simulation device, the sample simulation device is respectively communicated with a freezing circulation device, a grouting device and a water replenishing device, and a data acquisition device is arranged on the sample simulation device; the testing device adopted in the invention is simple to operate, and can apply ground stress to the soil mass sample and inject the modifying agent so as to simulate and test the frost heaving deformation rule of the ground surface in the soil mass freezing process under the coupling of multiple factors such as water content, initial ground stress, temperature gradient and the like.
Description
Technical Field
The invention relates to the technical field of indoor geotechnical low-temperature tests, in particular to a frozen soil moisture migration and frost heaving rule testing device and a testing method.
Background
The artificial freezing method is a method for freezing water in the stratum by using an artificial refrigeration technology, changing natural rock soil into frozen soil, increasing the strength and stability of the frozen soil, isolating underground water and enabling surrounding rock to have certain bearing capacity so as to conveniently perform tunnel excavation and support under the protection of a frozen wall. The freezing method has the advantages of good safety, wide application range, good flexibility, good controllability, less pollution and the like, and is widely applied to the construction process of underground engineering in recent years. However, researches show that during the formation of the frozen soil curtain, moisture in the soil body can migrate to the vicinity of the frozen wall under the actions of self gravity, matrix suction and temperature gradient, the frozen soil expands in volume after the moisture is frozen, so that the volume of the frozen soil is increased, and the generated frost heaving force easily causes large deformation of the overlying ground surface and adjacent buildings.
In the water-rich sand layer, the porosity of the sand layer is larger, the permeability coefficient is high, underground water is rich and the supply amount is larger, the frost heaving effect is obvious, the frozen soil is large in amount and high in formation speed, and the frost heaving has larger influence on the stratum. In severe cases, the upper line of the existing tunnel cannot be normally operated, and great economic loss and severe social influence are caused. Therefore, improving the soil mass and mastering the water migration amount and the frost heaving deformation rule of the improved soil mass in the artificial freezing process provide effective reference basis and reliable theoretical support for the design and construction of a freezing method, and the problem to be solved is already urgently needed.
At the present stage, the water migration and frost heaving rule of the frozen soil body mainly has the following defects:
1) The influence of the initial ground stress of the soil body on the water migration rule is ignored, the soil body is regarded as a loose body to be tested, and the research result is greatly different from the actual result;
2) Only considering the frost heaving deformation rule of the soil body under the influence of single factors such as initial moisture content, temperature gradient and the like, the real-time monitoring and recording of the frost heaving deformation rule of the soil body under the influence of multiple factors are difficult to realize;
3) In the freezing process, the soil state in the soil sample bin is invisible, and the diffusion process of the freezing frontal surface cannot be directly observed;
4) The fresh device can simulate the injection process of the soil modifier and test the water migration and frost heaving rule in the freezing process of the modified soil.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a device and a method for testing the water migration and frost heaving rule of a frozen soil body, and solves the problems that the real occurrence environment of the soil body is ignored and the influence of the injection of a soil body modifying agent on the water migration and frost heaving rule in the freezing process of the modified soil body is not considered in the existing freezing test.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
on the one hand, the device for testing the water migration and frost heaving law of the frozen soil body comprises a sample simulation device, wherein the sample simulation device is arranged in a loading device, the loading device is used for carrying out ground stress simulation loading on a soil body sample in the sample simulation device, the sample simulation device is respectively communicated with a freezing circulation device, a grouting device and a water replenishing device, and a data acquisition device is arranged on the sample simulation device.
The testing device adopted by the invention is simple to operate, can apply ground stress to the soil sample and inject the modifying agent, can simulate the modified soil freezing process indoors, and can test the frost heaving deformation rule of the ground surface in the soil freezing process under the coupling of multiple factors such as water content, initial ground stress, temperature gradient and the like.
Further, the sample simulation device comprises a soil body sample bin which is internally provided with a soil body sample and is transparent, an upper cold bath box is movably arranged above the soil body sample bin, a lower cold bath box is arranged below the soil body sample bin, a cooling liquid inlet and a cooling liquid outlet are arranged on the upper cold bath box and the lower cold bath box, the cooling liquid inlet and the cooling liquid outlet are communicated with the freezing circulation device, a grouting port is reserved on the lower cold bath box, and the grouting port is communicated with the grouting device and the water supplementing device respectively.
In this scheme, be provided with cold bath box and lower cold bath box on the soil body sample storehouse, and soil body sample storehouse is the transparence, adopts above-mentioned scheme, and the soil body sample storehouse that is the transparence can audio-visually observe the frost heaving process of the soil body and the extension process that freezes the frontal, can exert the cold source of different external temperatures to sample soil body upper portion and lower part through last cold bath box and lower cold bath box.
Further, be provided with data acquisition device in the soil body sample storehouse, data acquisition device includes external terminal, and external terminal links to each other with multiunit sensor respectively and installs the displacement meter signal on last cold bath box, and multiunit sensor from top to bottom is equidistant to be laid on the same vertical face in the soil body sample storehouse, and every group sensor includes moisture sensor and the temperature sensor signal that the level was laid, and moisture sensor and temperature sensor link to each other with external terminal signal.
In this scheme, be provided with data acquisition device in the soil body sample storehouse, adopt above-mentioned scheme, data acquisition device includes external terminal, sensor and displacement meter, but the sensor real-time supervision freezes the inside moisture of in-process sample soil body and temperature variation process, and the displacement meter can measure the frost heave volume of the soil body in-process that freezes.
Further, the loading device comprises a reaction frame, the reaction frame comprises three supporting plates, the three supporting plates are connected through supporting columns, a groove is formed in the supporting plate located at the lowest position, a lower cooling bath box in the soil body sample bin is embedded into the groove, a grouting opening in the lower cooling bath box penetrates through the groove and is communicated with the grouting device and the water supplementing device respectively, a through hole is formed in the supporting plate located in the middle, and the top of the soil body sample bin is embedded into the through hole.
In this scheme, loading device includes the reaction frame, adopts above-mentioned scheme, and well two lower backup pads are used for confirming and fixed soil body sample storehouse, provide reverse effort for loading device through the backup pad of the superiors, make loading device load to soil body sample storehouse.
Furthermore, the loading device also comprises a hydraulic jack, one end of the hydraulic jack is arranged on the upper cold bath box, and the other end of the hydraulic jack is connected with the supporting plate positioned on the uppermost layer.
In the scheme, the loading device further comprises a hydraulic jack, and by adopting the scheme, the soil body sample is loaded through the hydraulic jack, so that the water and soil pressure of the soil body under the real occurrence condition is simulated.
Furthermore, a pressure measuring instrument is arranged between the hydraulic jack and the supporting plate positioned on the uppermost layer, and the pressure measuring instrument is electrically connected with the pressure display instrument.
In this scheme, be provided with pressure measurement appearance between hydraulic jack and the backup pad, adopt above-mentioned scheme, can real time monitoring hydraulic jack loaded pressure.
Further, the grouting device comprises a pneumatic grouting pump, the pneumatic grouting pump is communicated with the air compressor, the stirring barrel for containing bentonite slurry and the grouting port respectively, and a stirrer is arranged in the stirring barrel.
In this scheme, the grouting device includes pneumatic grouting pump, adopts above-mentioned scheme, and air compressor provides certain slip casting pressure for pneumatic grouting pump, and pneumatic grouting pump provides the power of extraction bentonite mud, and the mixer can stir the bentonite mud in the agitator in real time, prevents phenomenons such as deposit from appearing in the bentonite mud.
Further, the water supplementing device comprises a non-pressure water supplementing bottle, the non-pressure water supplementing bottle is communicated with the grouting port, a flow meter is arranged at the outlet of the non-pressure water supplementing bottle, and the bottom of the non-pressure water supplementing bottle is as high as the bottom of the soil sample in the soil sample bin.
In this scheme, the moisturizing device includes the non-pressure water supply bottle, adopts above-mentioned scheme, and the height of non-pressure water supply bottle bottom and soil body sample bottom is the same, can be in order to realize freezing the non-pressure moisturizing of in-process soil body sample to through the size of flowmeter real-time supervision freezing the moisture migration rate and the moisture migration volume of in-process soil body.
Furthermore, the freezing circulation device comprises two groups of low-temperature constant-temperature tanks for heating or refrigerating, wherein an operation panel is arranged on each low-temperature constant-temperature tank, and a temperature display screen for displaying temperature and an adjusting button for adjusting the temperature are integrated in the operation panel;
one of the low-temperature constant-temperature tanks is communicated with a cooling liquid inlet and a cooling liquid outlet of the upper cold bath box to form circulating flow;
and the other low-temperature constant-temperature groove is communicated with a cooling liquid inlet and a cooling liquid outlet of the lower cold bath box to form circulating flow.
In the scheme, the freezing circulating device comprises two groups of low-temperature constant-temperature tanks for heating or refrigerating, and by adopting the scheme, the two groups of low-temperature constant-temperature tanks for heating or refrigerating provide different temperatures so as to apply different temperature gradients between the upper surface and the lower surface of a soil body sample and facilitate observation of water migration in the frozen soil body.
On the other hand, the test method adopting the frozen soil body water migration and frost heaving rule test device comprises the following steps:
step S1, sample filling: equally dividing a soil body sample into 3 parts according to mass, equally dividing a soil body sample bin into 3 parts according to volume, adding the soil body sample into the soil body sample bin in a layering manner, adopting a vibration compaction instrument to carry out vibration compaction on the soil body sample so as to enable the soil body sample to reach a compact state, leveling the surface of the soil body sample, and embedding a moisture sensor and a temperature sensor at corresponding positions in the layering filling process of the soil body;
s2, installing a sample soil pressure bin: placing a soil body sample bin filled with a soil body sample in a groove on a support plate positioned at the lowest part of a reaction frame, embedding the top of the soil body sample bin into a through hole of a middle support plate, and placing an upper cold bath box provided with a sealing ring at the top of the soil body sample bin to plug the soil body sample bin so that the soil body sample bin is in a sealed state;
s3, installing a loading device: installing a hydraulic jack between the upper cold bath box and the uppermost supporting plate, opening the hydraulic jack, loading the soil body sample, stopping the loading of the hydraulic jack when the pressure value reaches a preset value, and keeping the loading stable;
step S4, modifier injection: opening an air compressor, conveying air pressure to a pneumatic grouting pump, injecting bentonite slurry into a soil sample by the pneumatic grouting pump, and closing a slurry stop valve after grouting is finished;
s5, mounting a displacement meter: after the ground stress loading of the soil mass sample is finished, mounting a displacement meter on the surface of the upper cold bath box;
step S6, freezing test: opening a freezing circulation device, setting a test target temperature, communicating cooling liquid with an upper cold bath box and a lower cold bath box through a pipeline circulation pipe after the temperature reaches a preset temperature, opening a water supplementing device, freezing and supplementing water to a soil mass sample in a soil mass sample bin to freeze the soil mass, and acquiring test data through a water content sensor, a temperature sensor and a displacement meter by an external terminal in the test process;
step S7, finishing the test: when the data collected by the moisture sensor, the temperature sensor and the displacement meter tend to be stable, the freezing circulation device and the water replenishing device are closed, and the test is finished;
step S8, data arrangement: and (3) arranging the data collected by the moisture sensor, the temperature sensor and the displacement meter, and drawing the change images of the moisture content, the temperature and the deformation of the soil body samples at different depths along with time.
The invention discloses a frozen soil body water migration and frost heaving rule testing device, which has the beneficial effects that:
1. the testing device adopted in the invention is simple to operate, the loading device applies ground stress to the soil sample to simulate the real occurrence state of the soil, the grouting device improves the soil sample, the water content, the temperature and the frost heaving amount in the soil sample in the freezing process are monitored in real time through the data acquisition device, the improved soil freezing process can be simulated indoors, and the frost heaving deformation rule of the ground surface in the soil freezing process under the coupling of multiple factors such as the water content, the initial ground stress and the temperature gradient is simulated.
2. The soil body sample bin is transparent, the frost heaving process of the soil body and the expansion process of the freezing frontal surface can be visually observed, and the condition that the freezing frontal surface is invisible in the conventional experimental process is solved.
3. The invention adopts the loading device to load the soil body sample, and solves the problem that the deviation between the test result and the field monitoring data is larger because the soil body cannot be stressed in the traditional test process.
4. The freezing circulation device is simple in design and easy to operate, cold sources with different external temperatures can be applied to the upper portion and the lower portion of the sample soil body, the measurement accuracy of the temperature control system is high, and fine control over the temperature can be achieved.
5. According to the invention, the bentonite is injected into the soil sample by adopting the grouting device, so that the soil improvement process by the modifier is truly simulated.
6. According to the invention, the non-pressure water replenishing bottle is adopted to realize the non-pressure uniform water replenishing of the improved soil sample in the freezing process.
Drawings
Fig. 1 is a schematic structural diagram of a frozen soil moisture migration and frost heaving law testing device of the invention.
FIG. 2 is a schematic view showing the structure of a sample simulation apparatus and a data acquisition apparatus according to the present invention.
Fig. 3 is a schematic structural diagram of a loading device of the present invention.
Fig. 4 is a schematic structural diagram of the grouting device of the invention.
Fig. 5 is a schematic structural view of the freeze cycle apparatus of the present invention.
Wherein, 1, a sample simulator; 11. a soil body sample bin; 12. putting the cold bath box; 13. a lower cold bath box; 14. a coolant inlet; 15. a coolant outlet; 16. a grouting port; 2. a loading device; 21. a reaction frame; 211. a support plate; 212. a support pillar; 22. a hydraulic jack; 23. a pressure gauge; 24. a pressure display instrument; 25. a groove; 26. (ii) a 3. A freeze cycle device; 31. a low-temperature constant-temperature tank; 32. an operation panel; 33. a temperature display screen; 34. an adjustment button; 4. a grouting device; 41. a pneumatic grouting pump; 42. a stirring barrel; 43. an air compressor; 44. a blender; 5. a water replenishing device; 51. a non-pressure water replenishing bottle; 52. a flow meter; 6. a data acquisition device; 61. an external terminal; 62. a moisture sensor; 63. a temperature sensor; 64. a displacement meter.
Detailed Description
The embodiments of the present invention are described so as to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
Example 1
Referring to fig. 1 and fig. 2, a schematic structural diagram of a frozen soil moisture migration and frost heaving law testing apparatus according to this embodiment is shown, and is intended to solve the problem that the actual occurrence environment of a soil is ignored in the existing freezing test, and the influence of the injection of a soil modifier on the moisture migration and frost heaving law in the freezing process of the improved soil is not considered, and a detailed description will be given to a specific structure of the apparatus below.
The utility model provides a frozen soil body moisture migration and frost heaving law testing arrangement, its includes sample analogue means 1, and sample analogue means 1 sets up in loading device 2.
Specifically, the loading device 2 carries out ground stress simulation loading on the soil mass sample in the sample simulation device 1 so as to simulate the real occurrence environment of the soil mass, and the problem that the ground stress cannot be applied to the soil mass in the traditional test process, so that the test result and the field monitoring data have large deviation is solved.
The sample simulation device 1 is respectively communicated with the freezing circulation device 3, the grouting device 4 and the water supplementing device 5, and a data acquisition device 6 is arranged on the sample simulation device 1.
The sample simulation device 1 comprises a transparent soil sample bin 11 with a soil sample inside, an upper cold bath box 12 is movably arranged above the soil sample bin 11, and a lower cold bath box 13 is arranged below the soil sample bin 11.
In this embodiment, the soil body sample chamber 11 is cylindrical and transparent, is made of a transparent acrylic plate, has a wall thickness of 1cm, a height of 60cm and an inner diameter of 20cm, and can visually observe the frost heaving process and the expansion process of the freezing frontal surface of the soil body.
The upper cold bath box 12 and the lower cold bath box 13 are both provided with a cooling liquid inlet 14 and a cooling liquid outlet 15, the cooling liquid inlet 14 and the cooling liquid outlet 15 are both communicated with the freezing circulating device 3, the freezing circulating device 3 provides cooling liquid, the cooling liquid is sent into the upper cold bath box 12 and the lower cold bath box 13 through pipelines, and the upper cold bath box 12 and the lower cold bath box 13 can apply cold sources with different external temperatures to the upper part and the lower part of a sample soil body.
A grouting opening 16 is reserved in the lower cold bath box 13, the grouting opening 16 is communicated with the grouting device 4 and the water replenishing device 5 respectively, a rubber water stop strip with the thickness of 3mm wraps the periphery of the upper cold bath box 12, the moisture in a soil sample is prevented from leaking out from a gap at the periphery of the upper cold bath box 12 in the loading process, the thicknesses of the upper cold bath box 12 and the lower cold bath box 13 are both 5cm, and the upper cold bath box and the lower cold bath box are made of aluminum alloy.
The soil body sample cabin 11 is internally provided with a data acquisition device 6, the data acquisition device 6 comprises an external terminal 61, and the external terminal 61 is respectively connected with a plurality of groups of sensors and a displacement meter 64 arranged on the upper cold bath box 12 through signals.
In this embodiment, a plurality of sets of sensors are arranged on the same vertical plane in the soil mass sample cabin 11 at equal intervals from top to bottom, each set of sensors includes signals of a moisture sensor 62 and a temperature sensor 63 which are horizontally arranged, and the moisture sensor 62 and the temperature sensor 63 are connected with external terminal signals.
The data acquisition device 6 comprises an external terminal 61, a sensor and a displacement meter 64, wherein the sensor can monitor the moisture and temperature change process inside a sample soil body in the freezing process in real time, the displacement meter 64 can measure the frost heaving amount in the soil body freezing process, and the external terminal 61 in the embodiment is a computer.
The testing device adopted in the invention is simple to operate, the loading device 2 applies ground stress to the soil sample to simulate the real occurrence state of the soil, the grouting device 4 improves the soil sample, the data acquisition device 6 monitors the water content, the temperature and the frost heaving amount in the soil sample in the freezing process in real time, the improved soil freezing process can be simulated indoors, and the frost heaving deformation rule of the ground surface in the soil freezing process under the coupling of multiple factors such as the water content, the initial ground stress and the temperature gradient is simulated.
In the case of the example 2, the following examples are given,
referring to fig. 3, a schematic structural diagram of the loading device in this embodiment is provided to apply a ground stress to the soil body and simulate a real occurrence state of the soil body.
The loading device 2 comprises a reaction frame 21, wherein the reaction frame 21 comprises three supporting plates 211, and the three supporting plates 211 are connected through supporting columns 212.
Specifically, the supporting plate 211 is a disc-shaped plate made of steel, four circular holes with a diameter of 15mm are reserved around the supporting plate, and the number of the supporting columns 212 is 4 in total
And (4) manufacturing the twisted steel.
A groove 25 is formed in the supporting plate 211 located at the lowest position, the lower cold bath box 13 in the soil body sample bin 11 is embedded into the groove 25, the grouting port 16 in the lower cold bath box 13 penetrates through the groove 25 to be communicated with the grouting device 4 and the water supplementing device 5 respectively, a through hole is formed in the supporting plate 211 located in the middle, and the top of the soil body sample bin 11 is embedded into the through hole.
In this embodiment, the middle and lower support plates 211 are used to determine and fix the soil sample bin 11, and the support plate 211 on the uppermost layer provides a reverse acting force for the loading device 2, so that the loading device 2 can load the soil sample in the soil sample bin 11, and simulate the water and soil pressure under the real occurrence condition of the soil.
The loading device 2 further comprises a hydraulic jack 22, one end of the hydraulic jack 22 is installed on the upper cooling bath box 12, the other end of the hydraulic jack 22 is connected with the supporting plate 211 located on the uppermost layer, and the soil body sample is loaded through the hydraulic jack 22 to simulate water and soil pressure of the soil body under the real occurrence condition.
A pressure measuring instrument 23 is arranged between the hydraulic jack 22 and the supporting plate 211 positioned on the uppermost layer, the pressure measuring instrument 23 is electrically connected with the pressure display instrument 25, the pressure measuring instrument 23 can monitor the pressure loaded by the hydraulic jack 22 in real time, and the current pressure is displayed on the pressure measuring instrument 23.
Example 3
Referring to fig. 4 and fig. 5, the structural schematic diagrams of the grouting device and the freezing cycle device in this embodiment are shown, in order to improve the soil sample in the freezing test and provide a cold source, and this embodiment provides further solutions of the grouting device and the freezing cycle device.
The grouting device 4 includes a pneumatic grouting pump 41.
Specifically, the pneumatic grouting pump 41 is respectively communicated with an air compressor 43, an agitator 42 for containing bentonite slurry, and the grouting port 16, and an agitator 44 is provided in the agitator 42.
In this embodiment, the air compressor 43 provides a certain grouting pressure for the pneumatic grouting pump 41, the pneumatic grouting pump 41 provides power for extracting bentonite slurry, the stirrer 44 can stir the bentonite slurry in the stirring barrel 42 in real time to prevent the bentonite slurry from depositing and the like, the air compressor 43 and the pneumatic grouting pump 41 both adopt the prior art, wherein the model of the air compressor 43 is TG160B, and the model of the pneumatic grouting pump 41 is ZBQ-50.
The water replenishing device 5 comprises a non-pressure water replenishing bottle 51, the non-pressure water replenishing bottle 51 is communicated with the grouting port 16, and a flow meter 52 is arranged at the outlet of the non-pressure water replenishing bottle 51.
In this embodiment, the bottom of the non-pressure water replenishing bottle 51 is as high as the bottom of the soil sample in the soil sample bin 11, that is, the non-pressure water replenishing of the soil sample in the freezing process can be realized, and the flow meter 52 monitors the moisture migration rate and the moisture migration amount of the soil in the freezing process in real time.
The freezing cycle device 3 includes two groups of cryostat tanks 31 for heating or cooling, an operation panel 32 is arranged on the cryostat tank 31, and a temperature display screen 33 for displaying temperature and an adjusting button 34 for adjusting temperature are integrated in the operation panel 32.
In this embodiment, the volume of the cryostat 31 is 15L, and the coolant may be selected from alcohol, anhydrous silicone oil, and the like, as required for the test temperature.
The two groups of low-temperature constant-temperature tanks 31 for heating or refrigerating provide different temperatures so as to apply different temperature gradients between the upper surface and the lower surface of the soil sample, thereby facilitating observation of water migration in the frozen soil.
One of the cryostat tanks 31 is in communication with the coolant inlet 14 and the coolant outlet 15 of the upper cold bath box 12 to form a circulating flow for cooling.
The other cryostat 31 is in communication with the coolant inlet 14 and the coolant outlet 15 of the lower cold bath box 13 to form a circulating flow for heating.
The temperature range of the low-temperature constant-temperature tank 31 is-30-100 ℃, and the mechanism is beneficial to the migration of water in frozen soil body so as to facilitate observation.
Example 4
Referring to fig. 1 to 5, the present embodiment provides a test method using a frozen soil moisture migration and frost heaving law testing apparatus, which includes the following steps:
step S1, sample filling: equally dividing the soil sample into 3 parts by mass, equally dividing the soil sample bin 11 into 3 parts by volume, adding the soil sample into the soil sample bin 11 in a layering manner, compacting the soil sample by vibration with a vibration compacting instrument to enable the soil sample to reach a compact state, leveling the surface of the soil sample, and embedding the moisture sensor 62 and the temperature sensor 63 at corresponding positions in the layering filling process of the soil sample.
S2, installing a sample soil pressure bin: the soil mass sample bin 11 filled with the soil mass sample is placed in the groove 25 on the supporting plate 211 positioned at the lowest part of the reaction frame 21, the top of the soil mass sample bin 11 is embedded into the through hole of the middle supporting plate 211, and the upper cooling bath box 12 provided with the sealing ring is placed at the top of the soil mass sample bin 11 to seal the soil mass sample bin 11, so that the soil mass sample bin 11 is in a sealing state.
S3, installing a loading device: the hydraulic jack 22 is arranged between the upper cold bath box 12 and the uppermost supporting plate 211, the hydraulic jack 32 is opened, the soil sample is loaded, and when the pressure value reaches a preset value, the hydraulic jack 32 is stopped from loading and is kept stable.
Step S4, modifier injection: and (3) opening the air compressor 43, conveying air pressure to the pneumatic grouting pump 41, injecting bentonite slurry into the soil sample by the pneumatic grouting pump 41, and closing the slurry stop valve after grouting is finished.
S5, mounting a displacement meter: after the soil mass sample is loaded with the ground stress, the displacement meter 64 is installed on the surface of the upper cold bath box 12.
Step S6, freezing test: the freezing circulation device 3 is started, the test target temperature is set, when the temperature reaches the preset temperature, the cooling liquid is communicated with the upper cold bath box 12 and the lower cold bath box 13 through pipeline circulation pipes, the water supplementing device 5 is started to freeze and supplement water for the soil mass samples in the soil mass sample cabin 11, the soil mass is frozen, and the external terminal 61 collects test data through the moisture sensor 62, the temperature sensor 63 and the displacement meter 64 in the test process.
Step S7, finishing the test: and when the data collected by the moisture sensor 62, the temperature sensor 63 and the displacement meter 64 tend to be stable, closing the freezing circulation device 3 and the water replenishing device 5, and ending the test.
Step S8, data arrangement: and (3) data collected by the moisture sensor 62, the temperature sensor 63 and the displacement meter 64 are collated, and images of changes of moisture content, temperature and deformation of soil body samples at different depths along with time are drawn.
While the embodiments of this invention have been described in detail, it should not be considered limited to such details. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.
Claims (10)
1. The utility model provides a freeze soil body moisture migration and frost heaving law testing arrangement which characterized in that: comprises a sample simulation device (1);
the sample simulation device (1) is arranged in a loading device (2), and the loading device (2) is used for carrying out ground stress simulation loading on a soil mass sample in the sample simulation device (1);
the sample simulation device (1) is respectively communicated with the freezing circulation device (3), the grouting device (4) and the water replenishing device (5), and the sample simulation device (1) is provided with a data acquisition device (6).
2. The frozen soil moisture migration and frost heaving law testing device of claim 1, wherein: the sample simulation device (1) comprises a transparent soil sample bin (11) with a soil sample inside, an upper cold bath box (12) is movably arranged above the soil sample bin (11), and a lower cold bath box (13) is arranged below the soil sample bin (11);
the upper cooling bath box (12) and the lower cooling bath box (13) are respectively provided with a cooling liquid inlet (14) and a cooling liquid outlet (15), and the cooling liquid inlet (14) and the cooling liquid outlet (15) are respectively communicated with the freezing circulating device (3);
and a grouting opening (16) is reserved on the lower cold bath box (13), and the grouting opening (16) is communicated with the grouting device (4) and the water supplementing device (5) respectively.
3. The frozen soil moisture migration and frost heaving law testing device of claim 2, wherein: a data acquisition device (6) is arranged in the soil body sample bin (11), the data acquisition device (6) comprises an external terminal (61), and the external terminal (61) is respectively in signal connection with a plurality of groups of sensors and a displacement meter (64) arranged on the upper cold bath box (12);
the multiple groups of sensors are distributed on the same vertical surface in the soil body sample bin (11) at equal intervals from top to bottom; each group of sensors comprises signals of a moisture sensor (62) and a temperature sensor (63) which are horizontally arranged, and the moisture sensor (62) and the temperature sensor (63) are connected with external terminal signals.
4. The frozen soil moisture migration and frost heaving law testing device of claim 2, wherein: the loading device (2) comprises a reaction frame (21), the reaction frame (21) comprises three supporting plates (211), and the three supporting plates (211) are connected through supporting columns (212);
a groove (25) is formed in the supporting plate (211) which is positioned at the lowest position, a lower cold bath box (13) in the soil body sample bin (11) is embedded into the groove (25), and a grouting opening (16) in the lower cold bath box (13) penetrates through the groove (25) to be communicated with a grouting device (4) and a water supplementing device (5) respectively;
the middle supporting plate (211) is provided with a through hole, and the top of the soil body sample bin (11) is embedded into the through hole.
5. The frozen soil moisture migration and frost heaving law testing device of claim 4, wherein: the loading device (2) further comprises a hydraulic jack (22), one end of the hydraulic jack (22) is installed on the upper cooling bath box (12), and the other end of the hydraulic jack (22) is connected with the supporting plate (211) on the uppermost layer.
6. The frozen soil moisture migration and frost heaving law testing device of claim 5, wherein: the hydraulic jack (22) and the supporting plate (211) positioned on the uppermost layer are provided with a pressure measuring instrument (23) therebetween, and the pressure measuring instrument (23) is electrically connected with a pressure display instrument (25).
7. The frozen soil moisture migration and frost heaving law testing device of claim 2, wherein: the grouting device (4) comprises a pneumatic grouting pump (41), wherein the pneumatic grouting pump (41) is respectively communicated with an air compressor (43), a stirring barrel (42) for containing bentonite slurry and a grouting port (16); a stirrer (44) is arranged in the stirring barrel (42).
8. The frozen soil moisture migration and frost heaving law testing device of claim 7, wherein: moisturizing device (5) are including non-pressure water compensating bottle (51), non-pressure water compensating bottle (51) and slip casting mouth (16) intercommunication, the exit of non-pressure water compensating bottle (51) is provided with flowmeter (52), just the bottom height of soil body sample is the same in non-pressure water compensating bottle (51) bottom and soil body sample storehouse (11).
9. The frozen soil moisture migration and frost heaving law testing device of claim 2, wherein: the freezing circulation device (3) comprises two groups of low-temperature constant-temperature tanks (31) for heating or refrigerating, an operation panel (32) is arranged on the low-temperature constant-temperature tanks (31), and a temperature display screen (33) for displaying temperature and an adjusting button (34) for adjusting the temperature are integrated in the operation panel (32);
one of the low-temperature constant-temperature tanks (31) is communicated with a cooling liquid inlet (14) and a cooling liquid outlet (15) of the upper cooling bath box (12) to form circulating flow;
and the other low-temperature constant-temperature groove (31) is communicated with a cooling liquid inlet (14) and a cooling liquid outlet (15) of the lower cooling bath box (13) to form circulating flow.
10. A test method using the frozen soil moisture migration and frost heaving law testing apparatus according to any one of claims 1 to 9, wherein: the method comprises the following steps:
s1, sample filling: equally dividing a soil sample into 3 parts by mass, equally dividing a soil sample bin (11) into 3 parts by volume, adding the soil sample into the soil sample bin (11) in a layering manner, vibrating and compacting the soil sample by adopting a vibrating compactor to enable the soil sample to reach a compact state, leveling the surface of the soil sample, and embedding a moisture sensor (62) and a temperature sensor (63) at corresponding positions in the layering filling process of the soil sample;
s2, installing a sample soil pressure bin: placing a soil mass sample bin (11) filled with a soil mass sample in a groove (25) on a support plate (211) positioned at the lowest part of a reaction frame (21), embedding the top of the soil mass sample bin (11) into a through hole of a middle support plate (211), and placing an upper cooling bath box (12) provided with a sealing ring at the top of the soil mass sample bin (11) to seal the soil mass sample bin (11) so as to enable the soil mass sample bin (11) to be in a sealed state;
s3, installing a loading device: installing a hydraulic jack (22) between the upper cold bath box (12) and the uppermost supporting plate (211), opening the hydraulic jack (32), loading the soil body sample, and stopping the loading of the hydraulic jack (32) when the pressure value reaches a preset value and keeping the pressure value stable;
s4, injecting a modifier: opening an air compressor (43), conveying air pressure to a pneumatic grouting pump (41), injecting bentonite slurry into a soil sample by the pneumatic grouting pump (41), and closing a slurry stop valve after grouting is finished;
s5, mounting a displacement meter: after the ground stress loading of the soil mass sample is finished, a displacement meter (64) is arranged on the surface of the upper cold bath box (12);
s6, freezing test: opening the freezing circulation device (3), setting a test target temperature, communicating the cooling liquid with the upper cold bath box (12) and the lower cold bath box (13) through pipeline circulation pipes when the temperature reaches a preset temperature, and opening the water supplementing device (5) to freeze and supplement water for the soil mass sample in the soil mass sample bin (11) so as to freeze the soil mass;
in the test process, an external terminal (61) collects test data through a moisture sensor (62), a temperature sensor (63) and a displacement meter (64);
s7, finishing the test: when the data collected by the moisture sensor (62), the temperature sensor (63) and the displacement meter (64) tend to be stable, the freezing circulation device (3) and the water replenishing device (5) are closed, and the test is finished;
s8, data arrangement: and data collected by the moisture sensor (62), the temperature sensor (63) and the displacement meter (64) are collated, and images of changes of moisture content, temperature and deformation of soil body samples at different depths along with time are drawn.
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