CN108387619B - Tester for testing unfrozen water content of frozen soil under controllable stress state - Google Patents
Tester for testing unfrozen water content of frozen soil under controllable stress state Download PDFInfo
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- CN108387619B CN108387619B CN201810124800.2A CN201810124800A CN108387619B CN 108387619 B CN108387619 B CN 108387619B CN 201810124800 A CN201810124800 A CN 201810124800A CN 108387619 B CN108387619 B CN 108387619B
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- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/223—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance for determining moisture content, e.g. humidity
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Abstract
The invention discloses a frozen soil unfrozen water content testing instrument capable of controlling a stress state, which comprises an organic glass top cover embedded with a nondestructive TDR probe, wherein the organic glass top cover is arranged in a pressure chamber filled with antifreeze and is positioned above a soil sample, the organic glass top cover is connected with a vertical stress loading frame outside the pressure chamber through a loading rod and is used for applying a vertical load, the soil sample is connected with a freeze-thaw temperature control system for heat exchange, the antifreeze in the pressure chamber is connected with a hydraulic system and is used for applying confining pressure loading, the nondestructive TDR probe is connected with a signal transmitter through a coaxial cable, and the dielectric constant of a medium is obtained through pulse reflection signals so as to determine the unfrozen water content. After the loading system is added with the TDR nondestructive probe and the freeze-thaw temperature control system, the stress state is accurately controlled, the loading system works normally, and the unfrozen water content in the frozen soil in different stress states can be accurately tested.
Description
Technical Field
The invention belongs to the technical field of frozen soil unfrozen water content measurement, and particularly relates to a frozen soil unfrozen water content testing instrument capable of controlling a stress state.
Background
The perennial frozen soil area in china accounts for 22.3% of the territorial area of china, and is the third place in the world. One of the troublesome problems faced in infrastructure construction in frozen soil areas is frost heaving and thaw collapse of soil samples, such as uneven settlement after freeze thawing of highways and railroad beds, and inclined deformation after freeze thawing of building foundations. The frost heaving and thawing sinking of the soil sample are caused by the fact that liquid water and solid ice in pores generate phase change under the action of temperature, and further the volume of the soil sample is changed. According to the existing research, the freezing of liquid water in the soil sample is a gradual process along with the reduction of temperature. At negative temperature, partial pore water in the soil sample can reduce the self energy state through capillary and adsorption action and keep the liquid state. Therefore, determining the remaining unfrozen water content of the soil sample at a certain temperature is of great significance in estimating frost heaving and thaw collapse of the soil sample.
At present, methods for testing the unfrozen water content in frozen soil mainly comprise a thermal method, a time domain reflectometer method, a computerized analysis and identification technology method, a nuclear magnetic resonance instrument method and the like. However, most of the existing test instruments based on these methods measure the unfrozen water content of the soil sample under no load, which is not consistent with the in-situ conditions under which the soil sample is usually subjected to a certain stress state. Particularly, in geotechnical engineering, the stress state of a soil sample in the freezing process is not negligible when the soil sample is frequently contacted with frozen soil of a deeper soil layer. Therefore, the instrument capable of testing the unfrozen water content in the frozen soil under different stress states has an important effect on analysis of frost heaving and thaw collapse of the permafrost region.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a frozen soil unfrozen water content testing instrument capable of controlling the stress state, which is simple to operate and accurate in result and meets the actual requirements of scientific research and engineering.
The invention adopts the following technical scheme:
the utility model provides a frozen soil of steerable stress state does not freeze moisture content test instrument, including the organic glass top cap that inlays the harmless TDR probe, the organic glass top cap sets up in the pressure chamber that is filled with antifreeze, be located the top of soil sample, the organic glass top cap is connected with the outside vertical stress loading frame of pressure chamber through the loading rod and is used for applying vertical load, soil sample is connected with the freeze-thaw temperature control system who is used for the heat exchange, antifreeze is connected with hydraulic system in the pressure chamber and is used for applying the confined pressure loading, the harmless TDR probe is connected with signal transmitter through coaxial cable, obtain the dielectric constant of medium and then confirm not freeze the moisture content through the pulse reflection signal.
Specifically, the freeze thawing temperature control system is used for carrying out-20 to 0oAnd C, freeze-thaw cycling, wherein the freeze-thaw cycling comprises a spiral copper pipe ring arranged outside the soil sample in a surrounding manner, two ends of the spiral copper pipe ring are respectively connected with a pump, the pump is connected with a constant temperature controller, and an anti-freezing solution is arranged in the spiral copper pipe ring.
Specifically, a force sensor and a displacement sensor are respectively arranged on a loading rod outside the pressure chamber.
Specifically, the nondestructive TDR probe comprises three snake-shaped copper sheets, the snake-shaped copper sheets are manufactured through a printed circuit board, the snake-shaped copper sheets are arranged on the circuit board in parallel, the snake-shaped copper sheet positioned in the middle is connected with an inner conductor of the coaxial cable, and the rest two snake-shaped copper sheets are connected with an outer conductor of the coaxial cable.
Specifically, the distance between three snake-shaped copper sheets is 3-5 mm, the height of each snake-shaped copper sheet is 0.01-0.03 mm, and the width of each snake-shaped copper sheet is 1-2 mm.
Specifically, the diameter of the circuit board is 65-72 mm, and the thickness of the circuit board is 6-10 mm.
Specifically, the soil sample is a cylinder with the diameter of 76mm and the height of 20-40 mm.
Specifically, the outside of the pressure chamber is provided with heat insulation cotton.
Specifically, the unfrozen water content is calibrated by a dielectric mixing model, and specifically comprises the following steps:
wherein the content of the first and second substances,
to test the volumetric water content of the soil sample,
in order to calibrate the parameters, the calibration parameters are,
、
、
respectively the dielectric constants of soil particles, air and liquid water, n is the porosity of the soil sample,
is the dielectric constant of the soil sample.
Further, the dielectric constant of the soil sample
The following were used:
wherein the content of the first and second substances,
in order to calibrate the parameters, the calibration parameters are,
in order to be the speed of light,
in order for the instrument to measure the parameters,
the length of the middle snake-shaped copper sheet in the three parallel snake-shaped copper sheets in the nondestructive TDR probe is disclosed.
Compared with the prior art, the invention has at least the following beneficial effects:
the invention relates to a frozen soil unfrozen water content testing instrument capable of controlling a stress state, which is characterized in that a soil sample is placed in a pressure chamber filled with an antifreezing solution, an organic glass top cover embedded with a nondestructive TDR probe is arranged above the soil sample, the organic glass top cover is connected with a loading rod and used for realizing vertical load, the antifreezing solution is connected with a hydraulic system and used for realizing confining pressure loading, the soil sample is connected with a freeze-thaw temperature control system and used for realizing heat exchange, the nondestructive TDR probe is connected with a signal transmitter through a coaxial cable, the dielectric constant of a medium is obtained through pulse reflection signals so as to determine the unfrozen water content, and after the TDR nondestructive probe and the freeze-thaw temperature control system are added into the loading system, the stress state is accurately controlled, the operation is normal, and the.
Further, the freeze thawing temperature control system is used for carrying out-20 to 0oC, the freezing and thawing temperature control system works effectively, and the temperature distribution is uniform and the temperature change fluctuation is small in the formula sample in the balanced state.
Furthermore, a force sensor and a displacement sensor are respectively arranged on a loading rod outside the pressure chamber and used for testing the vertical load and the deformation applied to the soil sample. The two sensors are at a certain distance from the pressure chamber and insulated by the heat insulation cotton, so that the working temperature environment of the sensors is consistent with the indoor temperature.
Furthermore, the nondestructive TDR probe is made of a printed circuit board, the number of the snake-shaped copper sheets is three, the snake-shaped copper sheets are arranged on the circuit board in parallel, the length of the waveguide can be obviously reduced by the probe in the form, and non-insertion type nondestructive testing is carried out. The nondestructive TDR probe has stable test signals, easily identified reflection points in test waveforms, and can accurately determine the dielectric constant of a test medium.
Furthermore, the interval of snakelike copper sheet is 3~5mm, and highly is 0.01~0.03mm, and the width is 1~2mm, and the circuit board diameter is 65~72mm, and thickness is 6~10mm, and above-mentioned size sets up the test range that can satisfy harmless TDR probe and does not receive the influence of test medium dielectric property, and then guarantees that the demarcation relation of this probe test water content has very high correlation coefficient.
Furthermore, the diameter of the soil sample is 76mm, and the height is a cylinder of 20-40 mm. The diameter of the soil sample is consistent with that of the currently common three-axis sample, and the soil sample can be seamlessly connected with a universal three-axis instrument. The design height setting simultaneously satisfies the boundary effect influence of the organic glass top cover and the requirement of the nondestructive TDR probe on the test range in the vertical direction.
Furthermore, the calibration process of the nondestructive TDR probe for measuring the water content not frozen has the advantages of strong theoretical basis, simple process and R of calibration relation2The value is greater than 0.99.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a schematic view of a nondestructive TDR probe of the present invention;
FIG. 3 is a diagram showing the relationship between the calibration of the dielectric constant of the soil sample measured by the nondestructive TDR probe of the present invention;
FIG. 4 is a calibration graph of the present invention using the dielectric constant of a soil sample to calculate the unfrozen water content;
fig. 5 is a schematic diagram showing temperature changes monitored at different positions in a soil sample during freeze-thaw cycles, wherein (a) is the temperature change of the upper and lower boundaries of the outer surface of the soil sample, and (b) is the temperature change of the upper and lower boundaries of the outer surface of the soil sample and the temperature change of the center of the soil sample.
Wherein: 1. a loading rod; 2. a force sensor; 3. a displacement sensor; 4. a pressure chamber; 5. a helical copper pipe coil; 6. an organic glass top cover; 7. a vertical stress loading frame; 8. a switch; 9. a hydraulic system; 10. an antifreeze; 11. soil sampling; 12. heat preservation cotton; 13. a thermostatic controller; 14. a pump; 15. a coaxial cable; 16. a non-destructive TDR probe; 17. a coaxial cable outer conductor; 18. a coaxial cable inner conductor; 19. a circuit board; 20. a serpentine copper sheet.
Detailed Description
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "one side", "one end", "one side", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The invention provides a frozen soil unfrozen water content testing instrument capable of controlling a stress state. Nondestructive TDR probe is composed of printed circuit boardThe circuit board is technically manufactured by attaching three snake-shaped copper sheets on one circuit board, wherein the snake-shaped copper sheet in the middle and the copper sheets on two sides are respectively connected with the inner conductor and the outer conductor of the coaxial cable in a welding mode. The freezing and thawing temperature control system can be used for-20-0oFreeze-thaw cycling in the range of C. The triaxial apparatus can apply different horizontal and vertical stresses to the soil sample to simulate the stress state of the soil sample. Provides a powerful tool for testing the unfrozen water content in the frozen soil under different stress states.
Referring to fig. 1 and 2, the tester for unfrozen water content of frozen soil with controllable stress state of the invention comprises a nondestructive TDR probe 16, a freeze-thaw temperature control system and a triaxial apparatus, wherein an organic glass top cover 6 embedded with the nondestructive TDR probe 16 is placed above a soil sample 11, and is tested by an electromagnetic wave technology; a soil sample 11 is placed in a pressure chamber 4 of a triaxial apparatus, the upper end of an organic glass top cover 6 is connected with one end of a loading rod 1, the other end of the loading rod 1 is connected with a vertical stress loading frame 7, a force sensor 2 and a displacement sensor 3 are sequentially arranged on the loading rod 1 outside the pressure chamber 4, a spiral copper pipe coil 5 of a freeze-thaw temperature control system is arranged outside the soil sample 11 in a surrounding manner, two ends of the spiral copper pipe coil 5 are respectively connected with a thermostatic controller 13 through a pump 14, an antifreezing solution 10 is arranged in the spiral copper pipe coil 5, the same antifreezing solution 10 is arranged in the pressure chamber 4, the antifreezing solution 10 in the pressure chamber 4 is connected with a hydraulic system 9, the antifreezing solution 10 in the pressure chamber 4 is not connected with the antifreezing solution 10 in the spiral copper pipe coil 5, a snake-shaped copper sheet 20 on a nondestructive TDR probe 16 is connected with a signal emitter through a coaxial cable 15, when the water content is tested and is not frozen, an, the pulse propagates through the coaxial cable 15 and the snake-shaped copper sheet 20, is reflected at the place where the impedance discontinuity is encountered, and the reflected signal is recorded by an oscilloscope, and finally the dielectric constant of the medium is obtained by analyzing the reflected signal, and then the calculation of the unfrozen water content is carried out.
The freeze-thaw temperature control system consists of a constant temperature controller 13, a spiral copper pipe ring 5 and an anti-freezing solution 10, and the temperature of the anti-freezing solution 10 is controlled by the constant temperature controller 13; the spiral copper pipe ring 5 surrounds the soil sample 11, and the antifreeze 10 circulates through the spiral copper pipe ring 5;
the antifreeze solution 10 comprises water and water in a volume ratio of 1:1Ethylene glycol, the freezing point of the mixed solution in the proportion can reach-40oAnd C, meeting the requirements of engineering tests.
The triaxial apparatus is composed of a pressure chamber 4, a hydraulic system 9 and a vertical pressure loading frame 7, and a soil sample 11 is frozen or thawed through heat exchange with circulating antifreeze; in order to reduce energy loss and minimize temperature fluctuation of the soil sample 11, the pressure chamber 4 is subjected to adiabatic treatment by using low-thermal-conductivity heat-insulating cotton 12 (rubber cotton).
The horizontal stress state of the soil sample 11 applies confining pressure loading on the antifreeze 10 in the pressure chamber 4 through the hydraulic system 9; the vertical load is controlled by a vertical stress loading frame 7, a soil sample 11 is compressed due to the restraint of a loading rod 1 by moving a pressure chamber 4 arranged on the vertical stress loading frame 7 up and down, so that vertical stress is applied, the magnitude of the stress is measured by a force sensor 2 on the loading rod 1, and a displacement sensor 3 is used for testing the vertical displacement of the soil sample 11 in the loading process; different stress states of the soil sample 11 can be simulated through controlling the horizontal and vertical stress of the soil sample 11.
The nondestructive TDR probe 16 is manufactured by a printed circuit board, and three parallel snake-shaped copper sheets 20 are formed on one circuit board; the TDR probe 16 is welded with a coaxial cable 15 (the electrical impedance is 50 omega), a coaxial cable inner conductor 18 of the coaxial cable 15 is welded with a snake-shaped copper sheet 20 in the middle, and a coaxial cable outer conductor 17, namely a shielding layer, is welded with the other two snake-shaped copper sheets 20.
The diameter of a circuit board in the nondestructive TDR probe 16 is 65-72 mm, and the thickness is 6-10 mm; the distance between adjacent copper sheets in the three parallel snake-shaped copper sheets 20 is 3-5 mm, and the height and the width of each snake-shaped copper sheet 20 are 0.01-0.03 mm and 1-2 mm respectively;
the size of the soil sample 11 in the pressure chamber 4 is a cylinder with the diameter of 76mm and the height of 20-40 mm.
And a switch 8 is arranged on the base of the vertical stress loading frame 7 and is used for controlling a power supply for lifting or lowering the vertical displacement of the triaxial pressure chamber.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
When the triaxial apparatus is used for controlling the stress state of the soil sample, firstly, a pressure chamber is filled with water and glycol according to the ratio of 1:1, and then applying pressure to the antifreeze in the pressure chamber by a hydraulic system so as to control the horizontal stress state of the soil sample.
The pressure chamber arranged on the vertical stress loading frame is moved up and down, the loading rod is used for compressing the soil sample, the force sensor is used for testing the vertical stress, and the vertical stress state of the soil sample is controlled.
The distance between adjacent snake-shaped copper sheets is 5mm, the height and the width of each snake-shaped copper sheet 20 are respectively 0.02mm and 1mm, the diameter of the circuit board is 70mm, and the thickness of the circuit board is 6 mm.
The working principle is as follows:
1) the principle and calibration of unfrozen water content of a nondestructive TDR probe test:
firstly, calibrating the dielectric constant of a tested soil sample by using a nondestructive TDR probe, wherein the calibration formula is as follows:
wherein the content of the first and second substances,
in order to test the dielectric constant of the soil sample medium,
for calibrating parameters canCalibrated by measuring several sets of media of known dielectric constant,
is the speed of light: (
），
In order for the instrument to measure the parameters,
the length of the middle copper sheet in the three parallel serpentine copper sheets.
Referring to FIG. 3, tested by a nondestructive TDR probe
Has stronger quadratic curve relation with soil medium and calibrated correlation coefficient R2Up to 0.995.
Obtaining the dielectric constant of the soil sample 11, wherein the unfrozen water content is calibrated by a dielectric mixing model:
wherein the content of the first and second substances,
to test the volumetric water content of the soil sample,
for calibrating the parameters, the parameters can be calibrated by measuring several groups of soil sample 11 patterns with different water contents,
、
、
the dielectric constants (fixed constants) of the soil sample 11, air and liquid water, respectively, and n is the porosity of the soil sample 11.
Referring to FIG. 4, the dielectric constant of the soil sample medium tested by the nondestructive TDR probe
Has stronger power exponent relation with the volume water content of soil body, and the calibration parameter k is 0.57. The calibrated correlation coefficient reaches 0.991.
FIG. 5 is a graph showing the relationship between the dielectric constant of the soil sample 11 measured by the nondestructive TDR probe. It can be seen from the figure that there is a good linear relationship between the two. R of all calibration relations2All values are greater than 0.99.
2) Calibration of freeze-thaw temperature control system
In the freezing and thawing process, three thermocouples connected to the top (P-1), the middle (P-2) and the bottom (P-3) of the soil sample are used for testing the temperature of the soil sample, and the uniformity and the fluctuation of the temperature distribution in the soil sample 11 are verified. Freezing and thawing are applied in a step of-5 ℃ at a temperature of 20 ℃ to-20 ℃.
Fig. 5a shows the temperature changes measured at positions P-1 (upper border of the outer surface of the pattern) and P-2 (lower border of the outer surface of the soil sample) during the freeze-thaw cycle, and fig. 5b shows the temperature changes measured at positions P-1 (upper border) and P-3 (center of the soil sample) during the freeze-thaw cycle. The measurements in fig. 5 show that the temperature control system works effectively; the temperature fluctuation of the soil sample is less than 0.2 ℃ under the equilibrium state.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.
Claims (5)
1. The tester for testing the unfrozen water content of frozen soil in a controllable stress state is characterized by comprising an organic glass top cover (6) embedded with a nondestructive TDR probe (16), wherein the organic glass top cover (6) is arranged in a pressure chamber (4) filled with an antifreezing solution (10) and is positioned above a soil sample (11), the organic glass top cover (6) is connected with a vertical stress loading frame (7) outside the pressure chamber (4) through a loading rod (1) and is used for applying vertical load, a force sensor (2) and a displacement sensor (3) are respectively arranged on the loading rod (1) outside the pressure chamber (4), the soil sample (11) is connected with a freeze-thaw temperature control system for heat exchange, the freeze-thaw temperature control system is used for carrying out freeze-thaw cycle at-20-0 ℃, and comprises a spiral copper pipe ring (5) arranged outside the soil sample (11) in a surrounding manner, two ends of the spiral copper pipe ring (5) are respectively connected with a pump (14), the pump (14) is connected with the constant temperature controller (13), the spiral copper pipe ring (5) is internally provided with an antifreeze solution (10), the antifreeze solution (10) in the pressure chamber (4) is connected with the hydraulic system (9) and is used for applying confining pressure loading, the nondestructive TDR probe (16) comprises three snake-shaped copper sheets (20), the distance between the three snake-shaped copper sheets (20) is 3-5 mm, the height of each snake-shaped copper sheet (20) is 0.01-0.03 mm, the width is 1-2 mm, the diameter of the circuit board is 65-72 mm, and the thickness is 6-10 mm, the non-frozen water content measuring device is manufactured by a printed circuit board, the snake-shaped copper sheets (20) are arranged on the circuit board in parallel, the snake-shaped copper sheet (20) in the middle is connected with an inner conductor (18) of a coaxial cable, the remaining two snake-shaped copper sheets (20) are connected with an outer conductor (17) of the coaxial cable, a non-destructive TDR probe (16) is connected with a signal transmitter through a coaxial cable (15), and the non-frozen water content is determined by obtaining the dielectric constant of a medium through pulse reflection signals.
2. The apparatus for testing unfrozen water content of frozen soil under controllable stress state according to claim 1, wherein the soil sample (11) is a cylinder with a diameter of 76mm and a height of 20-40 mm.
3. The apparatus for testing the unfrozen water content of frozen earth under the controllable stress state according to claim 1, wherein the pressure chamber (4) is externally provided with heat insulation cotton (12).
4. The apparatus for testing unfrozen water content of frozen earth under controllable stress state according to claim 1, 2 or 3, wherein the unfrozen water content is calibrated by a dielectric mixing model, specifically:
wherein, thetawFor measuring the volume water content of the soil sample, k is a calibration parameter, epsilons、εw、εiRespectively the dielectric constants of soil particles, air and liquid water, n is the porosity of the soil sample, epsilona,soilIs the dielectric constant of the soil sample.
5. The apparatus for testing unfrozen water content of frozen soil under controllable stress state as claimed in claim 4, wherein the dielectric constant ε of the soil samplea,soilThe following were used:
wherein, a and b are calibration parameters, c is the speed of light, delta t is the instrument measurement parameter, and L is the length of the middle copper sheet in the three parallel snake-shaped copper sheets in the nondestructive TDR probe.
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| CN109781789A (en) * | 2019-02-27 | 2019-05-21 | 东南大学 | A kind of lossless multi-shot continuous measure device of masonry material water content |
| CN110320249B (en) * | 2019-07-12 | 2020-08-28 | 中国农业大学 | Frozen soil water potential measuring method |
| CN111122619B (en) * | 2019-12-31 | 2022-02-18 | 青岛海洋地质研究所 | Water content measuring system based on parallel spiral type telescopic time domain reflection probe |
| CN113447413A (en) * | 2021-05-19 | 2021-09-28 | 中国电建集团西北勘测设计研究院有限公司 | Unsaturated loess osmotic coefficient curve testing arrangement of steerable stress condition |
| CN113433155B (en) * | 2021-06-25 | 2024-01-30 | 中国矿业大学 | Real-time monitoring system and method for unfrozen water of roadbed in cold area |
| CN113433292A (en) * | 2021-06-25 | 2021-09-24 | 中国矿业大学 | System and method for testing evolution of microstructure of discrete sample under freeze-thaw cycle action |
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| SU1127945A1 (en) * | 1983-04-07 | 1984-12-07 | Государственный научно-исследовательский и проектный институт нефтяной и газовой промышленности им.В.И.Муравленко | Method for determining quantity of non-frozen water in frozen soils |
| CN103364415A (en) * | 2012-03-30 | 2013-10-23 | 中国科学院沈阳应用生态研究所 | Determination method for soil moisture in freeze thawing process of soil |
| CN106153644B (en) * | 2016-06-22 | 2018-12-14 | 湖南大学 | Three axis sample water content real-time testing of unsaturated soil probe and test device |
| CN206235522U (en) * | 2016-12-12 | 2017-06-09 | 中国科学院武汉岩土力学研究所 | A kind of Triaxial tester of soil body Frozen-thawed cycled dynamic load coupling |
| CN106769563A (en) * | 2016-12-12 | 2017-05-31 | 中国科学院武汉岩土力学研究所 | The Triaxial tester and its method of soil body Frozen-thawed cycled dynamic load coupling |
| CN206627352U (en) * | 2017-03-21 | 2017-11-10 | 中国科学院武汉岩土力学研究所 | A kind of triaxial apparatus with TDR measuring equipments |
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