CN110954573A - Unsaturated soil frost heaving instrument with multiple loading modes and frost heaving amount testing method - Google Patents
Unsaturated soil frost heaving instrument with multiple loading modes and frost heaving amount testing method Download PDFInfo
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Abstract
The invention discloses a multi-loading-mode unsaturated soil frost heaving instrument and a frost heaving amount testing method, wherein the frost heaving instrument comprises a sample storage system, a load control system, a humidity control system, a temperature control system and a thermostat; the sample storage system comprises a sample cylinder and a temperature disc, wherein the bottom end of the sample cylinder is provided with an air inlet, the temperature disc is internally provided with a cavity, the cavity bottom is externally provided with a water-proof air-isolating film, the cavity top is provided with a liquid inlet and a liquid outlet, the temperature disc is arranged in the top end of the sample cylinder, and the sample cylinder is arranged in a constant temperature box; the load control system comprises a reaction frame and a load control mechanism, the load control mechanism is arranged in the reaction frame, the reaction frame is erected in the constant temperature box, and the load control mechanism is arranged in the reaction frame and connected with the temperature disc; the humidity control system is communicated with an air inlet of the sample cylinder; the output port of the temperature control system is communicated with the liquid inlet on the temperature plate, and the outlet of the temperature control system is communicated with the liquid outlet on the temperature plate. The frost heaving test in a multi-loading mode can be developed, and gaseous water can be supplemented to induce frost heaving of coarse-grained soil.
Description
Technical Field
The invention belongs to the technical field of geotechnical engineering, and particularly relates to a multi-loading-mode unsaturated soil frost heaving instrument and a frost heaving amount testing method.
Background
The frost heaving of the roadbed is a main disease of cold area engineering, and particularly has great influence on cold area expressways, high-speed railways and the like. The experimental simulation is an important means for researching the frost heaviness of the roadbed filling. When the environment temperature in a cold area reaches negative temperature, the temperature of pore water in the soil reaches the freezing point and is frozen. The frost heaving of the roadbed needs to be supplemented with water, and the latest research results show that the migration of gaseous water is a core factor for inducing frost heaving of rock soil materials such as unsaturated coarse-grained soil. Such as unsaturated coarse-grained soil filler, is a main material of a high-speed railway roadbed, but in reports on a frost heaving phenomenon of a high-speed railway, theories and experiments about migration of gaseous water into ice are rarely involved.
The frost heaving of soil is always an important research subject in the field of geotechnical engineering, and the frost heaving test of soil is an important means for researching the frost heaving mechanism, the frost heaving sensitivity and other properties of the soil. The frost heaving amount and the frost heaving force are two important basic physical quantities of frozen soil and need to be measured through a frost heaving test of the soil. When the frost heaving characteristic of soil is researched, the free frost heaving amount under the no-load condition needs to be measured, namely the zero-load state of the soil is a prerequisite for measuring the free frost heaving amount of the soil. The overlying load is an important boundary condition of frost heaving of soil, and the frost heaving characteristic of the soil under different load conditions is an important basis for foundation design and the like of engineering subgrade in cold regions. The overlying static load is used for simulating the influence of static load on roadbed frost heaving, and the overlying dynamic load is used for simulating the influence of dynamic loads such as traffic load and the like on roadbed frost heaving.
Various frost heaving instruments are available at home and abroad, but the supply of gaseous water cannot be realized, and the pressure at the top of the soil sample (provided by the dead weight of a temperature disc and refrigerating fluid and the friction force between the temperature disc and a sample cylinder) cannot be eliminated. The frost heaving instrument which can not realize the supply of the gaseous water can not be used for researching the frost heaving characteristic of the roadbed filling materials such as unsaturated coarse-grained soil and the like. The pressure at the top of the soil sample cannot be eliminated, the measured frost heaving amount error is large, and the scientific research with higher requirements at the present stage cannot be met.
Disclosure of Invention
The invention aims to provide a multi-loading mode unsaturated soil frost heaving instrument capable of realizing gaseous water supply and inducing coarse soil frost heaving and a frost heaving amount testing method aiming at the defects of the prior art.
The invention provides a frost heaving instrument for unsaturated soil, which comprises a sample storage system, a load control system, a humidity control system, a temperature control system and a thermostat, wherein the sample storage system is used for storing a sample; the sample storage system comprises a sample cylinder and a temperature disc, wherein the bottom end of the sample cylinder is provided with an air inlet, the temperature disc is internally provided with a cavity, the cavity bottom is externally provided with a water-proof air-isolating film, the cavity top is provided with a liquid inlet and a liquid outlet, the temperature disc is arranged in the top end of the sample cylinder, and the sample cylinder is arranged in a constant temperature box; the load control system comprises a reaction frame and a load control mechanism, the load control mechanism is arranged in the reaction frame, the reaction frame is erected in the constant temperature box, and the load control mechanism is arranged in the reaction frame and connected with the temperature disc; the humidity control system is communicated with an air inlet of the sample cylinder; the output port of the temperature control system is communicated with the liquid inlet on the temperature plate, and the outlet of the temperature control system is communicated with the liquid outlet on the temperature plate.
Preferably, the sample cylinder is a cylinder with two open ends, the temperature sensor and the stress sensor are embedded in the sample cylinder at different heights, and the reinforcing mesh is arranged in the bottom of the sample cylinder.
Furthermore, the sample storage system also comprises a base, a positioning cylinder and a heat preservation cylinder; the base is an annular base, and the inner wall of the base is provided with a hygrothermograph and an electric heating rod; the top surface of the positioning cylinder is provided with a reinforcing mesh, and the positioning cylinder is coaxially arranged on the base; the sample cylinder is sleeved outside the positioning cylinder, and a sealing ring is arranged between the sample cylinder and the positioning cylinder; the heat preservation cylinder is coated outside the sample cylinder.
In a specific embodiment, the reaction frame is a door-shaped frame and comprises a cross beam and a pair of stand columns, the stand columns are provided with thread sections, through holes are formed in two ends of the cross beam, and the cross beam is sleeved on the two stand columns and locked through a pair of nuts.
In order to carry out the frost heaving test of action and static loading, the load control mechanism comprises a hydraulic servo control device and an axial force sensor; the hydraulic servo control device is arranged below the cross beam, and the loading end is connected with the temperature disc; the axial force sensor is arranged on the temperature disc.
In order to carry out a no-load frost heaving test, the load control mechanism comprises a winding drum, a sliding rope and a pulley; a winding drum is connected in the reaction frame, a pulley is connected below the cross beam, one end of a sliding cable is wound on the winding drum, and the other end of the sliding cable is connected with the temperature disc after being wound on the pulley; the reel rotates and lifts the temperature disc through the sliding rope, so that the load borne by the sample soil in the test process can be guaranteed to be always zero.
In one embodiment, the humidity control system includes an environmental tank, an air agitator, a heater, a cooler, a blower, a humidifier, and a dehumidifier; an air outlet and an air return opening are formed in the side wall of the environment box, the air blower is arranged at the air outlet, the output end of the air blower is communicated with the air inlet of the sample cylinder through a steam pipe, and the other end of the steam pipe is communicated with the air return opening; the bottom surface of the environment box is provided with a pair of through holes which are respectively communicated with the humidifier and the dehumidifier; the air stirrer is hung on the top surface of the environment box; the heater and the cooler are disposed on a bottom surface of the environmental chamber.
During specific implementation, the temperature control system comprises a temperature plate with a constant temperature or sine temperature, an output port of the temperature plate is communicated with a liquid inlet of the temperature plate, a backflow port is communicated with a liquid outlet, and the temperature is controlled through circulation of refrigerating fluid.
The invention also provides a method for testing the negative dynamic and static loads of unsaturated soil, which takes the frost heaving instrument as a tool and comprises the following steps:
(1) preparing sample soil, and placing the sample soil in a sample cylinder;
(2) covering a water-proof air-isolating film on the top of the sample;
(3) a temperature disc is arranged on the water-proof air-proof film;
(4) a hydraulic servo control device is arranged on the counterforce frame, so that the force application end is contacted with the temperature disk, and the initial position is recorded;
(5) setting a target relative humidity, and starting a humidity control system;
(6) setting a target temperature, starting a temperature control system, enabling refrigerating fluid to circularly enter a temperature disc, controlling the temperature, setting a target temperature of a thermostat, and starting the thermostat;
(7) setting a target overlaying pressure, and starting a hydraulic servo control device;
(8) and measuring, recording and storing relevant data, drawing a soil body temperature distribution curve according to the measured soil body temperature, solving the freezing depth, and obtaining the frost heaving rate through the frost heaving amount measured by the deformer.
The invention also provides a method for testing the free frost heaving amount of unsaturated soil, which takes the frost heaving instrument as a tool and comprises the following steps:
(1) preparing a sample, and placing the sample in a sample cylinder;
(2) covering a water-proof air-isolating film on the top of the sample;
(3) a temperature disc is arranged on the water-proof and air-proof film;
(4) a pulley is arranged on the counter-force frame;
(5) the sliding cable is connected with the temperature disc, the winding drum is rotated, and the sliding cable is adjusted to enable the temperature disc to just contact the top of the sample without pressure;
(6) starting a humidity control system to supply gaseous water;
(7) starting a temperature control device, and enabling refrigerating fluid to enter a temperature disc to realize temperature control;
(8) controlling the reel to rotate, lifting the sliding rope until the pressure at the top of the sample is zero, and maintaining the temperature plate to be in contact with the top of the sample so as to perform a zero-load frost heaving test; when the soil body is frozen and swelled upwards to cause the top to be loaded in the test process, the sliding rope is controlled to be continuously lifted through a signal transmitted by the pressure sensor between the temperature disc and the sample, and the fact that the upper load of the sample is always zero in the whole test process is guaranteed.
When the device is used, firstly, sample soil is placed in a sample cylinder, secondly, a water-proof air-isolation film and a temperature disc are laid, then different load control mechanisms are selected according to working conditions and are arranged under a reaction frame, frost heaving tests under different loads can be developed, the pressure on the top of the soil sample can be eliminated, the error of the measured frost heaving quantity is small, and scientific research with higher requirements at the present stage can be met; and meanwhile, the humidity control system and the temperature control system are started, so that steam can be injected into the sample soil in the sample cylinder to realize gaseous water supply, thereby inducing frost heaving of coarse-grained soil, and the method can be suitable for researching frost heaving characteristics of unsaturated coarse-grained soil and other roadbed fillers.
Drawings
Fig. 1 is a schematic view of a usage status of a first preferred embodiment of the present invention.
FIG. 2 is an enlarged schematic view of a sample storage system in accordance with a preferred embodiment.
Fig. 3 is an enlarged view of the assembly of the load control mechanism in the first preferred embodiment.
FIG. 4 is an enlarged schematic view of a humidity control system in accordance with one preferred embodiment.
FIG. 5 is an enlarged view of the connection between the temperature control system and the temperature disk in the first preferred embodiment.
Fig. 6 is an enlarged view of the assembly of the zero load control mechanism in the second preferred embodiment.
Sequence numbers of the drawings:
1-a sample storage system, 11-a sample cylinder, 12-a temperature disc, 13-a base, 14-a positioning cylinder, 15-a heat preservation cylinder, 16-a temperature sensor, 17-a stress sensor, 18-a water-resisting and gas-isolating film, 19-a reinforcing mesh;
2-a load control system, which is connected with a load control system,
21-reaction frame, 211-cross beam, 212-upright post, 213-nut,
22-load control mechanism, 221-hydraulic cylinder, 222-axial force sensor, 223-displacement sensor;
3-humidity control system, 31-environment box, 32-air stirrer, 33-heater, 34-cooler, 35-blower, 36-humidifier, 37-dehumidifier, 38-hygrothermograph;
4-temperature control system; 5, a thermostat; 6-steam pipe;
7-zero load control mechanism, 71-drum, 72-strop, 73-pulley.
Detailed Description
First preferred embodiment, as shown in fig. 1, the unsaturated soil frost heaving apparatus disclosed in this embodiment is suitable for performing unsaturated soil negative dynamic and static load frost heaving tests, and includes a sample storage system 1, a load control system 2, a humidity control system 3, a temperature control system 4, and a thermostat 5.
As shown in fig. 2, the sample storage system 1 includes a sample cartridge 11, a temperature disk 12, a base 13, a positioning cartridge 14, and a heat retention cartridge 15. The sample cylinder 11 is a cylinder with two open ends, is made of organic glass material, is perforated according to the target requirement on the cylinder wall, and is embedded with a temperature sensor 16 and a stress sensor 17 in the sample soil in the cylinder, wherein the temperature sensor 16 adopts a thermal resistor for measuring the soil body temperature of the sample soil, and the stress sensor 17 adopts a film type soil pressure cell. The temperature disc 12 is a cylindrical disc with the outer diameter matched with the inner diameter of the sample cylinder, is made of stainless steel, is internally provided with a cavity, the top of the cavity is provided with a liquid inlet and a liquid outlet, after sample soil is loaded into the sample cylinder, the temperature disc 12 is placed on the water-proof air-proof film 18 after the water-proof air-proof film 18 is laid, and the water-proof air-proof film 18 is made of PE materials and used for preventing wet air from entering the sample soil from the top. The base 13 is an annular base, and the inner wall of the base is provided with a hygrothermograph and an electric heating rod. The positioning cylinder 14 and the heat preservation cylinder 15 are both cylindrical cylinders, the outer diameter of the positioning cylinder 14 is matched with the inner diameter of the sample cylinder, a reinforcing mesh 19 is arranged on the top surface of the positioning cylinder, the opening area of the reinforcing mesh is not less than 50%, and the heat preservation cylinder 15 is made of glass wool. When the sample storage system is assembled, the positioning cylinder is coaxially arranged on the base, then the sample cylinder is sleeved outside the positioning cylinder, and the sealing ring is arranged between the positioning cylinder and the sample cylinder. The reinforcing mesh is an air inlet of the sample cylinder to ensure that steam can smoothly enter, then the sample soil is put into the sample cylinder, the water-resisting and air-isolating film is coated on the bottom surface of the sample soil, and then the temperature disc is arranged.
As shown in fig. 3, the load control system 2 includes a reaction frame 21 and a load control mechanism 22. The reaction frame 21 is a door-shaped frame and comprises a cross beam 211 and a pair of upright posts 212, threaded sections are arranged on the upright posts, through holes are formed in two ends of the cross beam, and the cross beam is sleeved on the two upright posts and locked through a pair of nuts 213, so that the height of the cross beam is adjustable. The load control mechanism 22 is connected below the cross beam, and the load control mechanism 22 comprises a hydraulic servo control device and an axial force sensor 222; a hydraulic cylinder 221 of the hydraulic servo control device is arranged below the cross beam, and an axial force sensor 222 is arranged outside the end part of the loading head; the displacement sensor 223 is provided on the temperature dial. During assembly, the sample storage system is placed in the thermostat 5, then the reaction frame of the load control system is spanned on the sample cylinder, and the loading end of the load control system is connected with the temperature disc. The hydraulic servo control device is in a TTCSUD-1 model, the axial force sensor is selected from SPX-2 type force sensing, and the displacement sensor is selected from LWX002 type linear displacement sensor.
As shown in fig. 4, the humidity control system 3 inputs steam into the sample soil in the sample cylinder 11 through the steam pipe 6. The humidity control system 3 includes an environment tank 31, an air agitator 32, a heater 33, a cooler 34, a blower 35, a humidifier 36, and a dehumidifier 37; the top of the environmental chamber 31 is provided with a thermo-hygrometer 38 for monitoring the temperature and humidity of the environmental chamber and feeding the measurement results back to the control system in time. The top surface of the environmental chamber 31 mounts an air agitator 32 for uniformly balancing the relative humidity within the environmental chamber. The bottom surface of the environmental chamber 31 is provided with a heater 33 and a cooler 34, wherein the heater is of the following types: KEW-M47 DR; the types of coolers are: and OR-60, which is used for heating and cooling the temperature of the environmental box respectively and maintaining the temperature of the environmental box in a dynamic balance state. An air outlet is arranged on one side of the environment box 31, an air return inlet is arranged on the other side of the environment box, and an air blower 35 is arranged at the air outlet and used for blowing steam into the sample cylinder through a steam pipe 6. The steam pipe 6 is a three-way pipe, one end of the steam pipe is communicated with an output port of the air blower, one end of the steam pipe is communicated with an air inlet of the sample cylinder, the other end of the steam pipe is communicated with an air return port, so that steam can start from the environment box, part of the steam enters the sample through an opening at the bottom of the sample, and part of the steam circulates back to the environment box. The bottom surface of the environmental box is also provided with a pair of through holes which are respectively communicated with the humidifier 36 and the dehumidifier 37, the humidifier 36 is an ultrasonic humidifier and selects a WM-SCA1000 type, and the dehumidifier 18 selects an EFA5-100-A type and is respectively used for increasing and reducing the relative humidity in the environmental box so as to ensure that the relative humidity in the environmental box is in a dynamic balance state.
As shown in fig. 5, the temperature control system 4 is a TMS8035-R40 type temperature control system, which can be set to a constant temperature or a sine-varying temperature, an output port of the temperature control system is communicated with a liquid inlet on the temperature disk, an output port of the temperature control system is communicated with a liquid outlet on the temperature disk, the refrigerating fluid flows into the temperature disk from the liquid inlet, the liquid outlet returns to the temperature tank after passing through the temperature disk, and the temperature is controlled by the circulation of the refrigerating fluid.
In this embodiment, the unsaturated soil frost heaving apparatus test with an overlying load for gaseous water replenishment is performed according to the following specific steps:
(1) connecting the related data line and the power line completely;
(2) screening and drying the soil, preparing the soil with different water contents, placing the prepared soil in a sample cylinder, layering and compacting the soil to a target height, preparing a target sample, and simultaneously embedding a temperature sensor and a stress sensor at the target height of the sample;
(3) covering a water-proof air-isolating film on the top of the sample;
(4) a temperature disc is arranged on the water-proof and air-proof film;
(5) a hydraulic servo control loading device is installed on the reaction frame, and the force transmission shaft is adjusted to be in contact with the temperature disc; the strain gauge was adjusted and the initial position was recorded.
(6) Setting a target relative humidity, and starting a humidity control system;
(7) setting a target temperature, starting a temperature control system, and enabling refrigerating fluid to circularly enter a temperature disc to control the temperature; setting a target temperature of the constant temperature box, and starting the constant temperature box;
(8) setting a target overlaying pressure, and starting a loading device;
(9) starting a data acquisition system, starting to measure, record and store related data;
(10) and drawing a soil body temperature distribution curve according to the measured soil body temperature to obtain a freezing depth delta H, and obtaining a frost heaving rate η through the frost heaving quantity delta H measured by the deformer:
wherein η is the frost heaving rate,. DELTA.h is the frost heaving amount,. DELTA.H is the freezing depth;
the implementation method of the frost heaving instrument can be used for engineering practice under the condition of considering overlying pressure. The free frost heaving amount under the no-load condition is an important basis for researching the frost heaving characteristic of soil and classifying the frost heaving sensitivity of rock and soil materials.
Second preferred embodiment, as shown in fig. 6, the present embodiment is different from the first preferred embodiment in that: the load control mechanism in this market implementation is selected as the zero load control mechanism 7. The zero load control mechanism 7 comprises a winding drum 71, a sliding rope 72 and a pulley 73; during assembly, a winding drum is connected into the reaction frame 21, a pulley is connected below the cross beam 211, one end of a sliding cable is wound on the winding drum, and the other end of the sliding cable is connected with the temperature disc 12 after being wound on the pulley; when the test is started, the winding drum rotates to lift the temperature disc through the sliding rope so as to enable the load borne by the sample soil to be zero; when the soil body is frozen and swelled upwards to cause the top to be loaded in the test process, the sliding rope is controlled to lift through a signal transmitted by the pressure sensor between the temperature disc and the sample, and the upper load of the sample is always zero in the whole test process.
The preferred embodiment is suitable for measuring the free frost heaving amount and the frost heaving stress of the soil under the condition of no load. The method comprises the following specific steps:
(1) connecting the related data line and the power line completely;
(2) screening and drying the soil, preparing the soil with different water contents, placing the prepared soil in a sample cylinder, layering and compacting the soil to a target height, preparing a target sample, and simultaneously embedding a temperature sensor and a stress sensor at the target height of the sample;
(3) covering a water-proof air-isolating film on the top of the sample;
(4) a temperature disc is arranged on the water-proof and air-proof film;
(5) a pulley is arranged on the reaction frame, the sliding cable is connected with the temperature disc, and the sliding cable is adjusted to enable the temperature disc to just contact the top of the sample without pressure; the strain gauge was adjusted and the initial position was recorded.
(6) Setting a target relative humidity, and starting a humidity control system;
(7) setting a target temperature, starting a temperature control system, and enabling refrigerating fluid to circularly enter a temperature disc to control the temperature; setting a target temperature of the constant temperature box, and starting the constant temperature box;
(8) controlling the drum to work, rolling up the sliding rope, and lifting the temperature scale through the sliding rope to eliminate the pressure at the top of the sample; when the pressure is zero, the sliding rope stops lifting, so that the temperature disc is kept in a non-pressure state when contacting the top of the sample;
(9) and starting a test, measuring, recording and storing related data, and controlling the lifting of the sliding rope through a signal transmitted by a pressure sensor between the temperature disc and the sample when the top of the soil body is loaded due to the fact that the soil body is frozen and swelled upwards in the test process, so that the overburden load of the sample is always zero in the whole test process.
In conclusion, the device can realize gaseous water supply so as to induce the frost heaving of coarse-grained soil, provides a test device for researching the frost heaving of soil body induced by gaseous water supply, and is suitable for researching the frost heaving characteristics of unsaturated coarse-grained soil and other roadbed fillers; the provided zero load control system provides a solution for measuring the free frost heaving amount of a soil body under the condition of no load; the hydraulic servo control loading system improves the measurement accuracy of the existing mechanical loading type frost heaving instrument. The implementation method of the dynamic and static loading type unsaturated soil frost heaving instrument capable of supplementing the gaseous water has the advantages of high precision, simplicity in operation, strong practicability and the like.
Claims (10)
1. The utility model provides a many loading modes's unsaturated soil frost heave appearance which characterized in that: the device comprises a sample storage system, a load control system, a humidity control system, a temperature control system and a thermostat;
the sample storage system comprises a sample cylinder and a temperature disc, wherein the bottom end of the sample cylinder is provided with an air inlet, the temperature disc is internally provided with a cavity, the cavity bottom is externally provided with a water-proof air-isolating film, the cavity top is provided with a liquid inlet and a liquid outlet, the temperature disc is arranged in the top end of the sample cylinder, and the sample cylinder is arranged in a constant temperature box;
the load control system comprises a reaction frame and a load control mechanism, the load control mechanism is arranged in the reaction frame, the reaction frame is erected in the constant temperature box, and the load control mechanism is arranged in the reaction frame and connected with the temperature disc;
the humidity control system is communicated with an air inlet of the sample cylinder;
the output port of the temperature control system is communicated with the liquid inlet on the temperature plate, and the outlet of the temperature control system is communicated with the liquid outlet on the temperature plate.
2. The multiple loading mode unsaturated soil frost heave apparatus of claim 1, wherein: the test sample cylinder is a cylinder with openings at two ends, temperature sensors and stress sensors are embedded in different heights of a test sample in the test sample cylinder, and a steel bar mesh is arranged in the bottom of the test sample cylinder.
3. The multiple loading mode unsaturated soil frost heave apparatus of claim 2, wherein: the sample storage system also comprises a base, a positioning cylinder and a heat preservation cylinder; the base is an annular base, and the inner wall of the base is provided with a hygrothermograph and an electric heating rod; the top surface of the positioning cylinder is provided with a reinforcing mesh, and the positioning cylinder is coaxially arranged on the base; the sample cylinder is sleeved outside the positioning cylinder, and a sealing ring is arranged between the sample cylinder and the positioning cylinder; the heat preservation cylinder is coated outside the sample cylinder.
4. The multiple loading mode unsaturated soil frost heave apparatus of claim 1, wherein: the reaction frame is a door-shaped frame and comprises a cross beam and a pair of stand columns, the stand columns are provided with thread sections, through holes are formed in two ends of the cross beam, and the cross beam is sleeved on the two stand columns and locked through a pair of nuts.
5. The multiple loading mode unsaturated soil frost heave apparatus of claim 4, wherein: the load control mechanism comprises a hydraulic servo control device and an axial force sensor; the hydraulic servo control device is arranged below the cross beam, and the loading end is connected with the temperature disc; the axial force sensor is arranged on the temperature disc.
6. The multiple loading mode unsaturated soil frost heave apparatus of claim 4, wherein: the load control mechanism comprises a winding drum, a sliding rope and a pulley; a winding drum is connected in the reaction frame, a pulley is connected below the cross beam, one end of a sliding cable is wound on the winding drum, and the other end of the sliding cable is connected with the temperature disc after being wound on the pulley; the reel rotates and lifts the temperature disc through the sliding rope, so that the load borne by the sample soil in the test process can be guaranteed to be always zero.
7. The multiple loading mode unsaturated soil frost heave apparatus of claim 1, wherein: the humidity control system comprises an environment box, an air stirrer, a heater, a cooler, a blower, a humidifier and a dehumidifier; an air outlet and an air return opening are formed in the side wall of the environment box, the air blower is arranged at the air outlet, the output end of the air blower is communicated with the air inlet of the sample cylinder through a steam pipe, and the other end of the steam pipe is communicated with the air return opening; the bottom surface of the environment box is provided with a pair of through holes which are respectively communicated with the humidifier and the dehumidifier; the air stirrer is hung on the top surface of the environment box; the heater and the cooler are disposed on a bottom surface of the environmental chamber.
8. The multiple loading mode unsaturated soil frost heave apparatus of claim 1, wherein: the temperature control system comprises a temperature plate with a constant temperature or sine temperature, an output port of the temperature plate is communicated with a liquid inlet of the temperature plate, a backflow port is communicated with a liquid outlet, and the temperature is controlled through circulation of refrigerating fluid.
9. A method for testing the frost heaving of unsaturated soil under negative dynamic and static loads, which is characterized in that the frost heaving instrument of claim 5 is used as a tool, and comprises the following steps:
(1) preparing sample soil, and placing the sample soil in a sample cylinder;
(2) covering a water-proof air-isolating film on the top of the sample;
(3) a temperature disc is arranged on the water-proof air-proof film;
(4) a hydraulic servo control device is arranged on the counterforce frame, so that the force application end is contacted with the temperature disk, and the initial position is recorded;
(5) setting a target relative humidity, and starting a humidity control system;
(6) setting a target temperature, starting a temperature control system, enabling refrigerating fluid to circularly enter a temperature disc, controlling the temperature, setting a target temperature of a thermostat, and starting the thermostat;
(7) setting a target overlaying pressure, and starting a hydraulic servo control device;
(8) and measuring, recording and storing relevant data, drawing a soil body temperature distribution curve according to the measured soil body temperature, solving the freezing depth, and obtaining the frost heaving rate through the frost heaving amount measured by the deformer.
10. A method for testing the free frost heaving amount of unsaturated soil, which is characterized in that the method uses the frost heaving instrument of claim 6 as a tool, and comprises the following steps:
(1) preparing a sample, and placing the sample in a sample cylinder;
(2) covering a water-proof air-isolating film on the top of the sample;
(3) a temperature disc is arranged on the water-proof and air-proof film;
(4) a pulley is arranged on the counter-force frame;
(5) the sliding cable is connected with the temperature disc, the winding drum is rotated, and the sliding cable is adjusted to enable the temperature disc to just contact the top of the sample without pressure;
(6) starting a humidity control system to supply gaseous water;
(7) starting a temperature control device, and enabling refrigerating fluid to enter a temperature disc to realize temperature control;
(8) controlling the reel to rotate, lifting the sliding rope until the pressure at the top of the sample is zero, and maintaining the temperature plate to be in contact with the top of the sample so as to perform a zero-load frost heaving test; when the soil body is frozen and swelled upwards to cause the top to be loaded in the test process, the sliding rope is controlled to be continuously lifted through a signal transmitted by the pressure sensor between the temperature disc and the sample, and the fact that the upper load of the sample is always zero in the whole test process is guaranteed.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911293622.7A CN110954573B (en) | 2019-12-16 | 2019-12-16 | Unsaturated soil frost heaving instrument with multiple loading modes and frost heaving amount testing method |
| CA3090105A CA3090105C (en) | 2019-12-16 | 2020-08-14 | Multi-load-mode frost heave tester for unsaturated soil and method for_testing amount of frost heave |
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Also Published As
| Publication number | Publication date |
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| CA3090105C (en) | 2022-08-02 |
| CN110954573B (en) | 2021-04-09 |
| CA3090105A1 (en) | 2021-06-16 |
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