CN114397321B - Soil three-phase separation device and method based on temperature and pressure effect - Google Patents
Soil three-phase separation device and method based on temperature and pressure effect Download PDFInfo
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- CN114397321B CN114397321B CN202111625103.3A CN202111625103A CN114397321B CN 114397321 B CN114397321 B CN 114397321B CN 202111625103 A CN202111625103 A CN 202111625103A CN 114397321 B CN114397321 B CN 114397321B
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Abstract
The invention discloses a soil body three-phase separation device and a separation method based on a warm-pressing effect, the separation device comprises a sealing tank, a heating unit, a gas collecting unit and a liquid collecting unit, a sample cavity for holding experimental soil body is formed in the sealing tank, the heating unit is arranged below the sample cavity, a top plate which is in direct contact with the experimental soil body is arranged above the sample cavity, the sample cavity is connected with the gas collecting unit and the liquid collecting unit through a pipeline, a suction pump is arranged at the tail end of the pipeline, the experimental soil body is heated, a condensing pipe and an air bag are utilized for collecting gas phase and liquid phase, and an oil film is combined for use, so that the soil body is prevented from losing gas phase before being heated in a test.
Description
Technical Field
The invention belongs to the field of soil gas content measurement, and particularly relates to a soil three-phase separation device and a separation method based on a temperature and pressure effect.
Background
Offshore oil and wind power have important roles in energy supply and energy upgrading in China, and the exploration and exploitation of oil and gas are completely dependent on pile foundation stability of offshore drilling platforms, wind power and other projects. These stabilities are all dependent on the mechanical properties of the seabed, in particular the strength, stiffness properties. However, the marine gas-containing sediment is widely distributed in the sea areas where marine construction is frequent, and under extreme sea conditions, the sudden release of the gas of the marine gas-containing sediment can drastically change the stability of the submarine sediment, so that the service safety of offshore structures such as drilling platforms, offshore wind power and the like is affected.
The gas type indicated in the marine gas-containing sediment refers to methane, in the prior art, the research on the gas content (methane content) of a soil body is less, and most of researches are to measure the gas content through triaxial experiments and the like after preparing the gas-containing soil in a laboratory. However, the gas content is difficult to define in the indoor test, and the CT scanning is basically performed indoors, but the CT scanning is very expensive, and the gas loss is caused in the transportation process after the gas-containing soil sample is prepared, so that the cost is high, and the measurement result is inaccurate. Aiming at the defects of high price and inaccurate result of the current indoor research on the gas content of the gas-containing soil, a gas phase duty ratio measuring device and a measuring method with simple structure, convenient operation, low cost and accurate measurement are needed to be provided.
Disclosure of Invention
The invention provides a soil three-phase separation device and a separation method based on a temperature-pressure effect, which are used for solving the defects of soil gas content (methane content) in the prior art.
The invention is realized by adopting the following technical scheme: the invention provides a soil three-phase separation device based on a temperature and pressure effect, which comprises a sealing tank, a heating unit, a gas collecting unit and a liquid collecting unit, wherein the sealing tank is connected with the heating unit;
the sealed tank comprises a shell, and sealing covers and bases which are arranged at the upper end and the lower end of the shell, and a sample cavity for holding experimental soil is formed in the sealed tank; the heating unit is arranged below the sample cavity, and a top plate is arranged above the sample cavity and is in direct contact with the experimental soil body; the sample cavity is connected with the gas collecting unit and the liquid collecting unit through a pipeline, and a suction pump is arranged at the tail end of the pipeline;
the liquid collecting unit comprises a condensing pipe connected with the pipeline and is used for condensing and collecting the liquid phase changed into gas to obtain the volume of the liquid phase;
the gas collection unit comprises a micro getter pump arranged behind the liquid collection unit, comprising a deflating balloon and connected to the deflating balloon 13.
Further, the heating unit comprises a heating element and a temperature diffusion element, the heating element is controlled by the external control unit to heat and raise the temperature, and uniform diffusion of the temperature is realized through the temperature diffusion element, so that the heating element is assisted, the whole soil body is ensured to be quickly heated, and meanwhile, the heat preservation effect can be achieved.
Further, the separation device also comprises a U-shaped water head pipe communicated with the sealing tank, and the water head height is higher than the upper interface of the experimental soil body;
the top plate is a slidable top plate, a piston is arranged on the slidable top plate, and the slidable top plate slides up and down along a sliding track of the inner wall of the sample cavity under the drive of the piston.
Further, a filter screen is further arranged at one end, close to the sealing tank, of the pipeline, the particle size of the filter screen is smaller than that of soil, and when the temperature of the device rises to a certain value, only gas phase in the soil and liquid phase converted into gas are allowed to pass through the filter screen and enter a subsequent device.
Furthermore, the surface of the experimental soil body in the sample cavity is further wrapped with a layer of oil film so as to ensure the accuracy of the experiment.
Further, the micro suction pump is used for enabling the gas phase to completely enter the shrinkage air bag, and a displacement sensor is arranged on the shrinkage air bag so as to measure the change of the air bag volume after the gas phase enters.
Further, the shell is made of heat-insulating materials or a heat-insulating layer is arranged on the surface of the shell.
Further, the side wall of the sealing tank is also provided with a pressure sensor and a plurality of longitudinal temperature sensors distributed at certain intervals, the top plate is provided with a plurality of transverse temperature sensors, and the temperature sensors are distributed to the whole experimental soil body so as to measure the temperatures of the experimental soil body in different directions; the pressure sensor is used for measuring the pressure in the sealed tank in real time.
The invention further provides a separation method of the soil three-phase separation device based on the temperature and pressure effect, which comprises the following steps:
step 1, experimental preparation:
(1) Preparing an experimental soil body according to experimental requirements, placing the prepared and remolded experimental soil body into a sealed tank body to prevent gas phase in the soil from escaping to the outside of equipment;
(2) Opening a suction pump to suck out the gas outside the soil body in the sealed tank, and vacuumizing;
(3) Opening a condensing pipe and a shrinkage air bag to collect a small amount of gas phase in the experimental soil before heating;
step 2, determining the volume of an experimental soil body:
before an experiment, a layer of oil film is distributed on the upper part of an experimental soil body to ensure that the total volume of the soil body is unchanged, and the three-phase proportion is fixed, so that the total volume V of three phases is obtained;
step 3, heating the experimental soil body;
regulating the heating element to a certain temperature, melting an oil film, and keeping for a certain time to ensure that gas phase in the soil body fully escapes, and then liquid phase vaporization escapes;
step 4, determining the liquid phase volume;
opening the suction pump to enable the gas phase and the gasified liquid phase to enter a subsequent link; adjusting the condensing tube to condense and liquefy the gasified liquid phase to collect the liquid phase, and obtaining the liquid phase volume V after the liquid phase volume in the condensing tube is stable and unchanged for a certain time w ；
Step 5, determining the gas phase volume;
the miniature suction pump is started to ensure that gas phase completely enters the shrinkage air bag, a displacement sensor is arranged on the shrinkage air bag to measure the change of the volume entering the shrinkage air bag, and the volume V of the gas phase is obtained after the numerical value is stable a ；
Step 6, determining solid-liquid-gas phase ratio;
by calculation, the solid phase volume V is obtained s ＝V-V a -V w The three-phase duty ratio can be obtained according to the volume ratio.
The invention further provides a frozen soil four-phase separation method of the soil three-phase separation device based on the temperature and pressure effect, which is used for realizing frozen soil four-phase separation and specifically comprises the following steps of:
step 1, preparing an experiment;
(1) After the frozen soil experimental soil body is well configured and remolded, placing the frozen soil experimental soil body into a sample cavity, and sealing the tank body to prevent gas phase in the soil from escaping to the outside of the equipment;
(2) Sealing the piston, fixing the top plate, opening the suction pump, sucking out the gas outside the soil body in the equipment, and vacuumizing;
(3) Opening a condensing pipe and a collecting air bag to collect a small amount of gas phase in the soil penetrating through the filter screen before heating;
step 2, determining the volume of an experimental soil body;
the piston is fixed, an oil film is arranged on the upper part of an experimental soil body before an experiment, the gas phase and the gasified liquid phase of the soil body are ensured not to escape, the four-phase proportion is fixed, and the total volume V of four phases is obtained 0 The method comprises the steps of carrying out a first treatment on the surface of the At the same time recording the initial pressure P of the sealed tank 0 ；
Step 3, heating the experimental soil body;
regulating the heating element to a certain temperature, melting an oil film, and keeping for a certain time to ensure that gas phase in the frozen soil experimental soil body is fully escaped, liquid phase vaporization is escaped along with the gas phase vaporization, ice melts the liquid phase and is vaporized along with the liquid phase vaporization, and all the gas phase enters a subsequent link through a filter screen;
step 4, determining the volume of the liquid phase and the ice phase;
opening the suction pump to enable the gas phase, the gasified liquid phase and the gasified ice phase to enter a subsequent link; regulating the condensing tube to condense and liquefy the gasified liquid phase and gasified ice phase, and obtaining the liquid phase and ice phase volume V after the liquid volume in the condensing tube is stable and unchanged for a certain time w，i ’；
Step 5, determining the gas phase volume;
the miniature suction pump is started to ensure that gas phase completely enters the shrinkage air bag, a displacement sensor is arranged on the shrinkage air bag to measure the change of the volume entering the shrinkage air bag, and the volume V of the gas phase is obtained after the numerical value is stable a ’；
Step 6, determining the volume of ice in the frozen soil;
when the gas collected by the shrinkage air bag is not increased any more and the condensed water in the condensing pipe is not increased any more, the frozen soil experimental soil body is filled with water and saturated through the U-shaped water head pipe, the water head in the U-shaped water head pipe is ensured to be higher than the soil body, and the top plate is in a slipping state, and then the piston is controlled to press the top plate downwards to drain waterTo an initial pressure value P 0 At the moment, the volume of soil in the equipment is V 1 ：
Calculate the volume change Δv=v 1 -v 0 ＝V i The volume of ice in the frozen soil;
step 7, determining four phases of solid, liquid and gas ice;
by calculation, the liquid phase volume V is obtained w ’＝V w，i ’-V i Volume of gas phase V a ' Ice phase volume V i ；
Then the solid phase volume V s ’＝V 0 -V i -V a ’-V W ' the ratio of each phase in the soil can be obtained according to the volume ratio.
Compared with the prior art, the invention has the advantages and positive effects that:
according to the indoor gas-containing soil three-phase measurement method and equipment designed by the scheme, the experimental soil body is heated, the condensing tube and the air bag are utilized for gas-phase liquid-phase collection, and the oil film is combined, so that the soil body is prevented from losing gas phase before experimental heating, the gas content of the gas-containing soil can be detected, the structural design principle is simple, the operation is convenient, the application is wider, and the method has important guiding significance for safety and stability research of a structural platform. And a U-shaped water head pipe communicated with the sealing tank is designed, and the sliding top plate can slide up and down along the sliding rail, so that the measurement of solid phase, liquid phase, refrigerator and gas phase in frozen soil is realized.
Drawings
Fig. 1 is a schematic structural diagram of a three-phase separation device according to embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of a frozen earth four-phase separation device according to embodiment 3 of the present invention.
Detailed Description
In order that the above objects, features and advantages of the invention will be more readily understood, a further description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced otherwise than as described herein, and therefore the present invention is not limited to the specific embodiments disclosed below.
The temperature gradient exists widely in the nature, and the cable buried underground is electrified for a long time to generate heat, so that the temperature gradient effect can be generated on surrounding soil. The change of temperature can cause the change of suction force, water content and the like in soil near the heat source, and the change of soil permeability, soil-water property and thermal-water-force coupling property. Therefore, the experimental device which can simulate the gas pressure change under the action of the temperature gradient and can measure the gas content is designed and developed, is used for researching the deformation rule and the gas phase ratio of the three-phase soil under the action of the temperature gradient, and is of great practical significance in closely combining the research and development of experimental instruments and equipment with the innovation of scientific research work.
In addition, in general, when the temperature of the soil is lower than 0 ℃, the moisture existing in the macropores of the soil starts to undergo phase change, and the moisture is changed from liquid water to solid ice; whereas capillary water in the soil and film water present on the soil surface are in liquid state, i.e. unfrozen water of the soil. The coexistence of water and unfrozen water in frozen soil has great influence on soil hydrologic process, thermodynamic property, mechanical property and environmental change process. Meanwhile, the stability of the area is influenced by the content of four phases in the frozen soil, and particularly, the shearing force of the frozen soil and the stability of the frozen soil slope are also influenced by the content of ice. Therefore, accurately measuring the ice content of frozen soil is an important index for researching the physical properties of frozen soil.
Embodiment 1, a soil body three-phase separation device based on warm-pressing effect, as shown in FIG. 1, includes a seal tank, a heating unit, a gas collection unit and a liquid collection unit, wherein the seal tank is composed of a housing 1, a seal cover 2 and a base 3, a sample cavity for holding experimental soil body is formed in the seal tank, the heating unit is arranged below the sample cavity, a top plate 6 is arranged above the sample cavity, the top plate 6 is in direct contact with the experimental soil body, the sample cavity is connected with the gas collection unit and the liquid collection unit through a pipeline, an air suction pump 11 is arranged at the tail end of the pipeline, and the liquid collection unit comprises a condensing pipe 12 for condensing liquid phase which becomes gasCollecting to obtain the volume v of liquid phase W The gas collecting unit comprises a shrinkage air bag 13 and a micro suction pump 14 connected with the shrinkage air bag 13, the shrinkage air bag 13 is used for collecting gas phase (methane) separated after condensation, the micro suction pump ensures that the gas phase completely enters the shrinkage air bag 13, and a displacement sensor is arranged on the shrinkage air bag 13 and can measure the change of the air bag volume after entering the gas phase.
A filter screen 10 is also arranged in the pipeline, the mesh particle diameter of the filter screen 10 is far smaller than the soil particle diameter, and when the temperature of the device rises to a certain value, only gas phase in the soil and liquid phase converted into gas are allowed to pass through the filter screen and enter a subsequent device;
the heating unit comprises a heating element 4 and a temperature diffusion element 5, the heating element 4 is controlled by the external control unit to heat and raise the temperature, and uniform diffusion of the temperature is realized through the temperature diffusion element 5 so as to assist the heating element, ensure rapid heating of the whole soil body, and simultaneously play a role in heat preservation.
In this embodiment, the casing 1 is made of a thermal insulation material, or the thermal insulation material is disposed on the side surface of the casing 1, and in addition, in order to ensure the accuracy of the experiment, the experimental soil body is further wrapped with a layer of oil film.
In addition, the side wall of the sealing tank is also provided with a pressure sensor 16 (pressure gauge) and a plurality of longitudinal temperature sensors 15 (thermometer) distributed at certain intervals, the sliding top plate 6 is provided with a plurality of transverse temperature sensors 9, and the temperature sensors are distributed to the whole soil body so as to measure the temperatures of the experimental soil body in different directions, and the temperature distribution of the soil body is ensured to be uniform by measuring the degrees in real time; the pressure sensor 16 is used to measure the pressure in the sealed can in real time.
The embodiment has simple and ingenious structural design, and the gas phase and liquid phase are collected by heating the experimental soil body and utilizing the condenser pipe and the air bag, and the use of an oil film is combined, so that the soil body is ensured not to have gas phase loss before experimental heating, and the gas content of the gas-containing soil is accurately and effectively detected.
Embodiment 2, based on the soil three-phase separation device proposed in embodiment 1, provides a three-phase soil separation method based on temperature and pressure effects, which comprises the following steps:
step 1, experimental preparation:
(1) Preparing an experimental soil body according to experimental requirements, placing the prepared and remolded experimental soil body into a sealed tank body to prevent gas phase in the soil from escaping to the outside of equipment;
(2) Opening a suction pump to suck out the gas outside the soil body in the equipment and vacuumizing;
(3) Keeping the filter screen 10 closed all the time, and opening the condensing tube 12 and the shrinkage air bag 13 to collect a small amount of gas phase in the experimental soil body penetrating the filter screen 10 before heating;
step 2, determining the volume of experimental soil
Before an experiment, a layer of oil film is distributed on the upper part of an experimental soil body to ensure that the total volume of the soil body is unchanged, and the three-phase proportion is fixed, so that the total volume v of three phases is obtained;
step 3, heating the experimental soil body;
adjusting the heating element to 150 ℃, melting an oil film, and keeping for 10 hours to ensure that gas phase in soil body is fully escaped, and liquid phase gasification is escaped along with the gas phase and enters a subsequent link through a filter screen;
step 4, determining the liquid phase volume;
opening the suction pump 11 to enable the gas phase and the gasified liquid phase to enter a subsequent link; the condenser tube 12 is regulated to condense and liquefy the gasified liquid phase to collect the liquid phase, and the volume v of the liquid phase is obtained after the volume of the liquid phase in the condenser tube is stabilized for 5 hours W ；
Step 5, determining the gas phase volume;
the micro suction pump 14 is turned on to ensure that the gas phase completely enters the shrinkage air bag 13, a displacement sensor is arranged on the shrinkage air bag 13 to measure the change of the volume entering the shrinkage air bag, and the volume V of the gas phase is obtained after the numerical value is stable A ；
Step 6, determining solid-liquid-gas phase ratio;
by calculation, the solid phase volume V is obtained S ＝V-V a -V w The three-phase duty ratio can be obtained according to the volume ratio.
The three-phase volume can be measured from the composition components of the experimental soil body, the device can be combined with other mechanical experiments, the soil body strength of which proportion distribution is explored is higher, and the device can be combined with other macroscopic properties. In the actual engineering, the soil mass property can be known only by heating the soil mass to know the three-phase proportion without sampling.
Embodiment 3, aiming at the characteristics of frozen soil, the embodiment is based on the device described in embodiment 1, and the improved design is carried out so as to realize the separation of four phases of frozen soil, namely, the frozen soil four-phase separation device based on the warm-pressing effect is designed.
The device is characterized by comprising a sealing tank, a heating unit, a gas collecting unit, a liquid collecting unit and a U-shaped water head pipe communicated with the sealing tank, wherein the water head height is higher than the upper interface of an experimental soil body, the sealing tank consists of a shell 1, a sealing cover 2 and a base 3, a sample cavity for containing the experimental soil body is formed in the sealing tank, the heating unit is arranged below the sample cavity, a top plate 6 is arranged above the sample cavity, the top plate 6 is a slidable top plate, a piston 8 is further arranged on the top plate 6, the slidable top plate 6 can slide up and down along a sliding rail 7 on the inner wall of the sample cavity, and the purpose of the piston 8 is to control the piston to downwards press the slidable top plate 6 when the temperature of equipment rises to a certain value, so that gas phase and liquid phase converted into gas in the soil are compressed to be separated from soil particles; the sliding top plate 6 is in direct contact with experimental soil body, the sample cavity is connected with the gas collecting unit and the liquid collecting unit through a pipeline, the tail end of the pipeline is provided with a suction pump 11, the liquid collecting unit comprises a condensing pipe 12 for condensing and collecting liquid phase changed into gas to obtain the volume v of the liquid phase W The gas collecting unit comprises a shrinkage air bag 13 and a micro suction pump 14 connected with the shrinkage air bag 13, the shrinkage air bag 13 is used for collecting gas phase, the micro suction pump ensures that the gas phase completely enters the shrinkage air bag 13, and a displacement sensor is arranged on the shrinkage air bag 13 and can measure the change of the air bag volume after entering the gas phase.
Other detailed designs are the same as those of example 1 and will not be described here.
Embodiment 4, based on the frozen soil four-phase separation device proposed in embodiment 3, provides a corresponding separation method, which specifically includes the following steps:
step 1, experimental preparation:
(1) After the frozen soil experimental soil body is well configured and remolded, placing the frozen soil experimental soil body into a sample cavity, and sealing the tank body to prevent gas phase in the soil from escaping to the outside of the equipment;
(2) Sealing the piston, fixing the top plate 6, opening the suction pump 11, sucking out the gas outside the soil body in the equipment, and vacuumizing;
(3) Opening a condensing pipe and a collecting air bag to collect a small amount of gas phase in the soil penetrating through the filter screen before heating;
step 2, determining the volume of experimental soil
The piston is fixed, an oil film is arranged on the upper part of an experimental soil body before an experiment, the gas phase and the gasified liquid phase of the soil body are ensured not to escape, the four-phase proportion is fixed, and the total volume V of four phases is obtained 0 The method comprises the steps of carrying out a first treatment on the surface of the At the same time recording the initial pressure p of the sealed pot 0 ；
Step 3, heating the experimental soil body;
regulating the heating element to a certain temperature, melting an oil film, and keeping for a certain time to ensure that gas phase in the frozen soil experimental soil body fully escapes, and evaporating liquid phase along with the gas phase, wherein ice melts the liquid phase and evaporates along with the liquid phase, and all the gas phase enters a subsequent link through a filter screen;
step 4, determining the volume of the liquid phase and the ice phase;
opening the suction pump 11 to enable the gas phase, the gasified liquid phase and the gasified ice phase to enter a subsequent link; the condenser tube 12 is regulated to condense and liquefy the gasified liquid phase and ice phase, and the volume V of the liquid phase and the ice phase is obtained after the volume of the liquid in the condenser tube is stable and unchanged for a certain time W，I ’；
Step 5, determining the gas phase volume;
the micro suction pump 14 is turned on to ensure that the gas phase completely enters the shrinkage air bag 13, a displacement sensor is arranged on the shrinkage air bag 13 to measure the change of the volume entering the shrinkage air bag, and the volume v of the gas phase is obtained after the numerical value is stable A ’；
Step 6, determining the volume of ice in the frozen soil;
after stabilization (air bag collected)No more gas and no more condensed water in the condensing pipe), the frozen soil experimental soil body is filled with water and saturated through the U-shaped water head pipe 17, the water head in the U-shaped water head pipe 17 is ensured to be higher than the soil body, the piston is opened to enable the top plate 6 to slide, and then the piston is pressed down to drain water until the initial pressure value p is reached 0 At the moment, the volume of soil in the equipment is V 1 ：
Calculate the volume change Δv=v 1 -V 0 ＝V i The volume of ice in the frozen soil;
step 7, determining four phases of solid, liquid and gas ice;
by calculation, the liquid phase volume V is obtained w ’＝V w，i ’-V i Volume of gas phase V a ' Ice phase volume V i ；
Then the solid phase volume V s ’＝V 0 -V i -V a ’-V w ' the ratio of each phase in the soil can be obtained according to the volume ratio.
It should be explained here that in the step 6, when determining the volume of ice, the principle thereof is as follows;
the water and methane gas exist in the gaps among soil particles, namely, the whole volume of the soil body is unchanged without the water and methane gas. However, after the ice exists, the ice exists among the soil particles, the volume of the soil body is changed, and after the ice exits, the volume of the soil body is changed. Because the top plate is tightly attached to the soil body, which is equivalent to a fixed volume, the pressure force after the ice is discharged must be reduced, and the pressure is changed by the water filling to recover the pressure before the ice is filled, so that the volume of the ice is obtained.
The present invention is not limited to the above-mentioned embodiments, and any equivalent embodiments which can be changed or modified by the technical content disclosed above can be applied to other fields, but any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical substance of the present invention without departing from the technical content of the present invention still belong to the protection scope of the technical solution of the present invention.
Claims (7)
1. The soil body three-phase separation device based on the temperature and pressure effect is characterized by comprising a sealing tank, a heating unit, a gas collecting unit and a liquid collecting unit;
the sealed tank comprises a shell (1), and sealing covers (2) and a base (3) which are arranged at the upper end and the lower end of the shell (1), and a sample cavity for holding experimental soil is formed in the sealed tank; the heating unit is arranged below the sample cavity and comprises a heating element (4) and a temperature diffusion element (5), the heating element (4) is controlled by the external control unit to heat and raise the temperature, the temperature diffusion element (5) is used for realizing uniform diffusion of the temperature, a top plate (6) is arranged above the sample cavity, the top plate (6) is in direct contact with an experimental soil body, and the surface of the experimental soil body is wrapped with a layer of oil film; the sample cavity is connected with the gas collecting unit and the liquid collecting unit through a pipeline, and a suction pump (11) is arranged at the tail end of the pipeline;
the liquid collecting unit comprises a condensing pipe (12) connected with the pipeline and is used for condensing and collecting liquid phase changed into gas to obtain the volume of the liquid phase; the gas collection unit comprises a miniature suction pump (14) which is arranged at the rear of the liquid collection unit and comprises a shrinkage air bag (13) and is connected with the shrinkage air bag (13);
the separation device also comprises a U-shaped water head pipe communicated with the sealing tank, and the water head height is higher than the upper interface of the experimental soil body;
the top plate (6) is a slidable top plate, a piston (8) is arranged on the slidable top plate (6), and the slidable top plate (6) slides up and down along a sliding track (7) on the inner wall of the sample cavity under the drive of the piston.
2. The soil body three-phase separation device based on temperature and pressure effect according to claim 1, wherein: a filter screen (10) is further arranged at one end, close to the sealing tank, in the pipeline, and the particle size of the filter screen (10) is smaller than that of soil.
3. The soil body three-phase separation device based on temperature and pressure effect according to claim 1, wherein: the miniature suction pump is used for enabling gas phase to completely enter the shrinkage air bag (13), and a displacement sensor is arranged on the shrinkage air bag (13) so as to measure the change of the air bag volume after the gas phase enters.
4. The soil body three-phase separation device based on temperature and pressure effect according to claim 1, wherein: the shell (1) is made of heat-insulating materials or a heat-insulating layer is arranged on the surface of the shell (1).
5. The soil body three-phase separation device based on temperature and pressure effect according to claim 1, wherein: the side wall of the sealing tank is also provided with a pressure sensor (16) and a plurality of longitudinal temperature sensors (15) distributed at certain intervals, the top plate (6) is provided with a plurality of transverse temperature sensors (9), and the temperature sensors are distributed to the whole experimental soil body so as to measure the temperatures of the experimental soil body in different directions; the pressure sensor (16) is used for measuring the pressure in the sealed tank in real time.
6. The separation method of the soil three-phase separation device based on the temperature and pressure effect as claimed in claim 1, which is characterized by comprising the following steps:
step 1, experimental preparation:
(1) Preparing an experimental soil body according to experimental requirements, placing the prepared and remolded experimental soil body into a sealed tank body to prevent gas phase in the soil from escaping to the outside of equipment;
(2) Opening a suction pump to suck out the gas outside the soil body in the sealed tank, and vacuumizing;
(3) Opening a condensing pipe (12) and a shrinkage air bag (13) to collect a small amount of gas phase in the experimental soil before heating;
step 2, determining the volume of an experimental soil body:
before an experiment, a layer of oil film is distributed on the upper part of an experimental soil body to ensure that the total volume of the soil body is unchanged, and the three-phase proportion is fixed, so that the total volume V of three phases is obtained;
step 3, heating the experimental soil body;
regulating the heating element to a certain temperature, melting an oil film, and keeping for a certain time to ensure that gas phase in the soil body fully escapes, and then liquid phase vaporization escapes;
step 4, determining the liquid phase volume;
opening the suction pump (11) to enable the gas phase and the gasified liquid phase to enter a subsequent link; the condensing tube (12) is regulated to condense and liquefy the gasified liquid phase to collect the liquid phase, and the volume V of the liquid phase is obtained after the volume of the liquid phase in the condensing tube is stable and unchanged for a certain time w ；
Step 5, determining the gas phase volume;
the miniature suction pump (14) is opened to ensure that gas phase completely enters the shrinkage air bag (13), a displacement sensor is arranged on the shrinkage air bag (13) to measure the change of the volume entering the shrinkage air bag, and the volume V of the gas phase is obtained after the numerical value is stable a ；
Step 6, determining solid-liquid-gas phase ratio;
by calculation, the solid phase volume V is obtained s ＝V-V a -V w The three-phase duty ratio can be obtained according to the volume ratio.
7. The frozen soil four-phase separation method based on the soil three-phase separation device based on the temperature and pressure effect as claimed in claim 1 is characterized by comprising the following steps:
step 1, experimental preparation:
(1) After the frozen soil experimental soil body is well configured and remolded, placing the frozen soil experimental soil body into a sample cavity, and sealing the tank body to prevent gas phase in the soil from escaping to the outside of the equipment;
(2) Sealing the piston, fixing the top plate (6), opening the suction pump (11), sucking out the gas outside the soil body in the equipment, and vacuumizing;
(3) Opening a condensing pipe and a collecting air bag to collect a small amount of gas phase in the soil penetrating through the filter screen before heating;
step 2, determining the volume of experimental soil
The piston is fixed, an oil film is arranged on the upper part of an experimental soil body before an experiment, the gas phase and the gasified liquid phase of the soil body are ensured not to escape, the four-phase proportion is fixed, and the total volume V of four phases is obtained 0 The method comprises the steps of carrying out a first treatment on the surface of the At the same time recording the initial pressure P of the sealed tank 0 ；
Step 3, heating the experimental soil body;
regulating the heating element to a certain temperature, melting an oil film, and keeping for a certain time to ensure that gas phase in the frozen soil experimental soil body is fully escaped, liquid phase vaporization is escaped along with the gas phase vaporization, ice melts the liquid phase and is vaporized along with the liquid phase vaporization, and all the gas phase enters a subsequent link through a filter screen;
step 4, determining the volume of the liquid phase and the ice phase;
opening the suction pump (11) to enable the gas phase, the gasified liquid phase and the gasified ice phase to enter a subsequent link; regulating the condensing tube (12) to condense and liquefy the gasified liquid phase and gasified ice phase, and obtaining the liquid phase and ice phase volume V after the liquid volume in the condensing tube is stable for a certain time w,i ’；
Step 5, determining the gas phase volume;
the miniature suction pump (14) is opened to ensure that gas phase completely enters the shrinkage air bag (13), a displacement sensor is arranged on the shrinkage air bag (13) to measure the change of the volume entering the shrinkage air bag, and the volume V of the gas phase is obtained after the numerical value is stable a ’；
Step 6, determining the volume of ice in the frozen soil;
when the gas collected by the shrinkage air bag is not increased any more and the condensed water in the condensing pipe is not increased any more, the frozen soil experimental soil body is filled with water and saturated through the U-shaped water head pipe (17), the water head in the U-shaped water head pipe (17) is ensured to be higher than the soil body, and the top plate (6) is in a slipping state, and then the piston is controlled to press the top plate (6) downwards to drain the water to an initial pressure value P 0 At the moment, the volume of soil in the equipment is V 1 ：
Calculate the volume change Δv=v 1 -V 0 ＝V i The volume of ice in the frozen soil;
step 7, determining four phases of solid, liquid and gas ice;
by calculation, the liquid phase volume V is obtained w ’＝V w,i ’-V i Volume of gas phase V a ' Ice phase volume V i ；
Then the solid phase volume V s ’＝V 0 -V i -V a ’-V w ' the ratio of each phase in the soil can be obtained according to the volume ratio.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105241920A (en) * | 2015-11-06 | 2016-01-13 | 天津城建大学 | Method for determining content of unfrozen water in soil freezing process by using specific heat calculation |
| CN105675434A (en) * | 2016-03-16 | 2016-06-15 | 中国地质大学（北京） | System and method for measuring gas content |
| CN107655926A (en) * | 2017-09-15 | 2018-02-02 | 北京化工大学 | A kind of Pyrolysis Experiment device and its method for pyrolysis |
| CN207439980U (en) * | 2017-12-05 | 2018-06-01 | 辽宁科技大学 | A kind of new carbon-based solid waste low temperature pyrogenation experimental provision |
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| CN108088757B (en) * | 2018-02-02 | 2019-02-19 | 中国矿业大学 | The three-axis force experimental rig and method of a kind of simulated high-pressure water congeals into ice process |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105241920A (en) * | 2015-11-06 | 2016-01-13 | 天津城建大学 | Method for determining content of unfrozen water in soil freezing process by using specific heat calculation |
| CN105675434A (en) * | 2016-03-16 | 2016-06-15 | 中国地质大学（北京） | System and method for measuring gas content |
| CN107655926A (en) * | 2017-09-15 | 2018-02-02 | 北京化工大学 | A kind of Pyrolysis Experiment device and its method for pyrolysis |
| CN207439980U (en) * | 2017-12-05 | 2018-06-01 | 辽宁科技大学 | A kind of new carbon-based solid waste low temperature pyrogenation experimental provision |
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