CN112098456A - Device for measuring salt swelling property of carbonized improved saline soil and operation method - Google Patents
Device for measuring salt swelling property of carbonized improved saline soil and operation method Download PDFInfo
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- CN112098456A CN112098456A CN202011087456.8A CN202011087456A CN112098456A CN 112098456 A CN112098456 A CN 112098456A CN 202011087456 A CN202011087456 A CN 202011087456A CN 112098456 A CN112098456 A CN 112098456A
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/16—Investigating or analyzing materials by the use of thermal means by investigating thermal coefficient of expansion
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- G—PHYSICS
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- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D21/00—Measuring or testing not otherwise provided for
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
- G01N33/246—Earth materials for water content
Abstract
The invention discloses a salt-swelling property measuring device and an operation method for carbonized modified saline soil, wherein the device consists of a curing agent mixing device, a carbonization device and salt-swelling property measuring equipment, and a movable core barrel is specially arranged to realize salt-swelling property test of untreated soil and carbonized soil and avoid disturbance and damage of the modified soil; the device has compact structure, simple connection mode, easy assembly and disassembly and small operation difficulty. The method can simulate complex environments under coupling conditions including temperature, underground water level, road surface load and the like, and accurately explore the influence of multi-factor change on the salt swelling property of the saline soil; the change of temperature, moisture and volume of the saline soil in the salt expansion process before and after improvement can be collected, the improvement process and the result can be accurately monitored and fed back in real time, and the automation degree of data collection is high; can be carbonized rapidly, the curing time is shortened, and meanwhile, the method is combined with typical soluble salt in soil, so that the concentration and alkalinity of soluble salt ions in the soil are greatly reduced, and a good treatment effect is realized.
Description
Technical Field
The invention belongs to civil engineering instrument devices and testing methods, and particularly relates to a device for measuring the salt swelling property of carbonized modified saline soil and an operation method.
Background
With the rapid development of economic construction in China, the demand of people on the infrastructure of roads, bridges, railways, various industries, civil buildings and the like is increased day by day, and in the process of constructing the infrastructure, the saline soil widely distributed in China restricts the development of infrastructure to a certain extent due to the special engineering characteristics of the saline soil. Generally, saline soil has poor engineering characteristics such as corrosivity, salt swelling property and collapsible property, and the salt swelling property is the most common and has great harm to engineering. Salt bloated nature takes place for salt affected soil usually because the temperature reduces the solubility that leads to salt affected soil salinity diminishes to combine together with the hydrone and form the crystal, produce certain expansibility to soil particle, lead to soil body structure to change, make soil body volume increase, form the salt bloated phenomenon. Meanwhile, the salt expansion phenomenon has a certain cumulative effect, and salt expansion amount accumulation can be formed in the process of multiple temperature changes, so that more serious damage can be caused to buildings, and therefore, the improvement of the saline soil and the salt expansion test are a technical problem to be solved urgently.
In the field of testing the salt swelling property of saline soil, students develop various testing instruments by diligent research, such as: a salt swell tester sample barrel (201610822948.4), a salt swell characteristic test device (201710172134.5) of saline soil, a salt swell crystallization pressure and frost swell salt swell comprehensive test device (201910915231.8) of saline soil and the like are all characterized in that the saline soil undergoes salt swell by directly or indirectly changing the temperature environment of the saline soil, and a dial indicator is used for testing the salt swell amount. The instruments can simply and quickly test the saline soil salinization, but simultaneously have the following defects: (1) the method is characterized in that the salt swelling capacity of original saline soil is simply tested, and is not combined with the improvement process of the saline soil, so that the change conditions of the salt swelling property of the saline soil in the improvement process and after the improvement are difficult to probe; (2) they all simulate only a single environmental factor, and are difficult to accurately simulate various complex natural environment variation factors. Therefore, it is a difficult problem to develop a salt expansion instrument which can improve saline soil and test salt expansion property and can simulate various environmental changes.
The study of the scholars finds that after the saline soil is solidified, the cementing product can wrap and cement the saline soil particles, so that when the temperature is reduced, salt in the soil is difficult to separate out crystals to cause volume expansion of the soil body, meanwhile, the structure of the soil body can be more compact, and the method is also beneficial to improving the strength of the soil body. Therefore, the improvement of the salt swelling property of saline soil by curing is gradually becoming a trend, such as: a protection method for improving salt swelling and salt sinking of saline soil (201010215078.7), a saline soil curing agent (201710176059.X) and the like. The curing agent prepared by inorganic cementing materials such as cement, lime, fly ash and the like is usually used for improving the salt expansion property of the saline soil, and has the advantages of good curing effect, small operation difficulty and easy operation. However, these curing agents have the following disadvantages: (1) the traditional curing agent for improving the salt swelling property of the saline soil requires at least 28 days of curing to form the saline soil, and is difficult to use quickly after the curing is finished; (2) the curing process of these curing agents is difficult to effectively monitor and control, and there is also a lack of effective comparative testing for the change in the salt swell of the saline soil before and after curing. Therefore, it is necessary to find a curing agent and a curing method which have high curing efficiency, controllable curing process and good effect on improving the salt swelling property. In recent years, geotechnical workers are actively exploring new curing agents and curing modes to replace the traditional curing agents and curing modes, and the inventor finds that the characteristics of simple operation, high curing efficiency, controllable process and environmental protection and green are achieved when alkaline materials and carbon dioxide are used for improving special soil, but the research field of the method for improving the salt expansion property of saline soil is blank.
Therefore, how to apply the method of carbonizing and curing the alkaline material and the carbon dioxide to the improvement of the salinization expansion of the salinized soil and test the performance of the salinization expansion of the improved soil body under various complex natural environment conditions becomes a difficult problem to be solved urgently, which has important significance for the civil engineering construction field and the salinization expansion improvement research field of the salinization soil in China.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a device for measuring the salinization expansion of carbonized improved salinized soil and an operation method thereof. The method has important significance for researching the influence rule of environmental factor change on the saline swelling property of the saline soil and applying the carbonization and solidification method to the improvement of the saline swelling property of the saline soil.
In order to achieve the purpose, the invention adopts the technical scheme that:
the invention relates to a device for measuring the salt expansion of carbonized modified saline soil, which comprises a curing agent mixing device, a carbonization device and a salt expansion measuring device, wherein the curing agent mixing device comprises a feed hopper A, a feed hopper B and a mixing device, the left side of the mixing device is connected with the feed hopper A through a feed conveying pipe, the feed hopper B is arranged above the mixing device, stirring blades are arranged in the mixing device, the right side of the mixing device is connected with a discharge pipe, a discharge valve is also arranged on the discharge pipe,
the carbonization device mainly comprises an outer frame cylinder, a core cylinder, a fixing device and a gas storage tank, wherein the core cylinder is arranged in the outer frame cylinder, the left side of the core cylinder is connected with a mixing device through a discharge pipe, the right side of the core cylinder is connected with the gas storage tank through a gas transmission pipe, a barometer is arranged on the right side of the core cylinder, a gas exhaust pipe is connected below the core cylinder, a gas exhaust valve is arranged on the gas exhaust pipe, the fixing device is fixed on the inner bottom surface of the outer frame cylinder,
the solidified soil test equipment mainly comprises a press machine, an upper refrigerating head, a lower refrigerating head, a vibrating plate, a permeable stone, a displacement meter, a water storage tower, a temperature sensor and a moisture sensor, wherein the press machine is arranged on a cross beam, the cross beam is arranged on the outer top surface of an outer frame barrel, the lower refrigerating head is arranged on the inner bottom surface of the core barrel, the vibrating plate and the permeable stone are sequentially arranged above the lower refrigerating head from bottom to top, the upper refrigerating head is arranged above the core barrel and connected with the press machine, the displacement meter is fixedly arranged above the upper refrigerating head, the water storage tower is connected with the core barrel through a water pipe, a water flow valve is arranged on the water pipe, the temperature sensor and the moisture sensor are fixed on the inner wall of the core barrel, the press machine is connected to a controller A through a data line, the upper refrigerating head and the lower refrigerating head are connected to a controller B through data lines, and the vibrating plate is, the temperature sensor, the moisture sensor and the displacement meter are all connected to data acquisition equipment through data lines, and the data acquisition equipment is connected to a computer through the data lines.
Preferably, the core barrel is made of corrosion-resistant rigid materials, and the outer surface of the water storage tower is marked with water level scale marks.
Preferably, the temperature of the upper refrigerating head and the lower refrigerating head can be adjusted within a range of-40 ℃ to 40 ℃.
Preferably, the wall of the right rear cylinder of the outer frame cylinder is connected to the frame through a hinge, the number of layers of the temperature sensor and the moisture sensor is determined according to the height of the core cylinder, and the distance between two adjacent layers of sensors is 5-10 cm.
Specifically, the operating method for measuring the salinity swelling property of the carbonized modified saline soil comprises the following steps:
a. basic property test of saline soil: taking a site saline soil sample, and obtaining the physicochemical indexes of the saline soil through a physicochemical test, wherein the physicochemical indexes comprise soil property, water content, natural density, pH value, salt composition and content;
b. testing the salt expansion amount of the saline soil: according to the natural density of the saline soil and the volume of the core barrel, calculating the mass of the required saline soil, weighing and pressing the required saline soil into the core barrel, then pushing the core barrel into the outer frame barrel until the core barrel is contacted with the fixing device, starting the operation controller A, and enabling the pressing machine to push the upper refrigerating head to be contacted with the upper surface of the saline soil; the water immersion depth and the overlying load of the soil body are adjusted through a water flow valve and a controller A, a probe of a displacement meter is adjusted to be in contact with an upper top cover of the outer frame cylinder, the rear side wall of the outer frame cylinder is closed, and the temperature of an upper refrigerating head and the temperature of a lower refrigerating head are opened and adjusted through a controller B; after the temperature is stable, reading numbers of a temperature sensor, a moisture sensor and a displacement meter of the saline soil under the action of the temperature gradient are tested;
c. mixing the saline soil and the alkaline curing agent: weighing a certain amount of saline soil according to the natural density of the saline soil and the volume of the core barrel, putting the saline soil into a feed hopper A, putting the saline soil into a mixing device through a feed delivery pipe, starting the mixing device, weighing a certain amount of alkaline curing agent and water according to the preset mixing amount of the curing agent and the water-cement ratio, putting the alkaline curing agent and the water into the mixing device through a feed hopper B, and uniformly stirring the mixture;
d. carbonizing and improving the saline soil mixture: opening a discharge valve to enable the mixture to flow into the core barrel, starting an operation controller A to enable a press machine to push an upper refrigeration head to compact the saline soil to a preset density, checking the air tightness of the core barrel, opening and adjusting an air delivery valve to enable a barometer to reach a preset air pressure, finally closing the barrel wall of the outer frame barrel, and performing ventilation and carbonization;
e. and (3) testing the salt expansion amount of the carbonized saline soil: adjusting the immersion depth and the overlying load of the soil body through a water flow valve and a controller A, adjusting a displacement meter to enable a probe of the displacement meter to be in contact with an upper top cover of an outer frame cylinder, starting a controller B and adjusting the temperature of an upper refrigerating head and a lower refrigerating head, and testing the readings of a temperature sensor, a moisture sensor and the displacement meter of the carbonized saline soil under the action of temperature gradient after the temperature is stable;
f. analyzing the improvement effect of the solidified salinized soil: analyzing the salt swelling treatment effect through the salt swelling change rate, wherein the salt swelling rate calculation formula is as follows:
wherein x is the salt-swelling reduction rate of the saline soil before carbonization, delta h1The salt expansion (mm) before carbonization, Delta h2The salt expansion (mm) is obtained after carbonization modification.
As a modification of the invention, the salt in the saline soil mainly comprises soluble salts as main components, including chloride, sodium sulfate and magnesium sulfate, the alkaline curing agent is one or a combination of more of active magnesium oxide, quick lime or carbide slag, the ventilation pressure is 25-300kPa, and the ventilation carbonization time is 3-24 hours.
As another modification of the invention, the content and the ventilation time of the alkaline curing agent are adjusted according to the soil property, the salt content and the ventilation pressure, and the higher the content and the salt content of the soil fine particles and the lower the ventilation pressure, the more the alkaline curing agent is mixed and the longer the ventilation time.
Compared with the prior art, the invention has the beneficial effects that:
(1) the movable core barrel is specially arranged, so that the salt expansion test of untreated soil and carbonized modified soil is realized, the salt expansion test of the carbonized modified salinized soil can be directly carried out, the disturbance and damage influence of the modified soil are avoided, and the salt expansion after field treatment can be accurately simulated.
(2) The method can simulate the complex environment change under the coupling conditions of temperature, underground water level, road surface load and the like, and accurately explore the influence of the change of natural environment factors on the salt swelling property of the saline soil.
(3) The device has the advantages of compact structure, good integrity, simple equipment connection mode, easy assembly and disassembly and small operation difficulty.
(4) The system can collect the temperature, moisture and volume changes of the saline soil in the processes of improvement and salinization before and after the improvement, can perform accurate monitoring and real-time feedback on the improvement process and the improvement result, has high data acquisition automation degree, and can probe the influence factors of improving the salinization of the saline soil.
(5) The saline soil adopts an improvement method combining alkalescence curing agent and carbon dioxide carbonization, can be quickly carbonized and improved, shortens the curing time, and simultaneously is combined with typical soluble salt in soil, greatly reduces the concentration and alkalinity of soluble salt ions in soil, and realizes good treatment effect.
Drawings
FIG. 1 is a schematic structural diagram of a test device for improving the salt swelling property of saline soil by carbonization and solidification;
FIG. 2 is a schematic structural diagram of a core barrel of a test device for improving the salt swelling property of saline soil through carbonization and solidification;
in the figure: 1. feed hoppers A, 2, feed conveying pipes, 3, a mixing device, 4, feed hoppers B, 5, mixing blades, 6, a discharge pipe, 7, a discharge valve, 8, an outer frame cylinder, 9, a core cylinder, 901, an upper refrigeration head, 902, permeable stones, 903, a vibrating plate, 904, a lower refrigeration head, 10, a fixing device, 11, a cross beam, 12, a press machine, 13, a gas conveying pipe, 14, a gas conveying valve, 15, a gas storage tank, 16, a water flow valve, 17, a water conveying pipe, 18, a water storage tower, 19, a displacement meter, 20, an exhaust pipe, 21, an exhaust valve, 22, a temperature sensor, 23, a moisture sensor, 24, data acquisition equipment, 25, a computer, 26, a gas pressure meter, 27, controllers A, 28, controllers B, 29 and a controller C.
Detailed Description
In order to make the objects, technical means, innovations and advantages of the present invention easier to understand, the present invention is further described in detail below with reference to the drawings. It should be understood that the location of device components and the description of specific embodiments in the illustrations of the invention are for purposes of explanation only and are not intended to limit the invention.
A device for measuring the salt expansion of carbonized modified saline soil is characterized by comprising a curing agent mixing device, a carbonization device and a salt expansion measuring device,
the curing agent mixing device mainly comprises a feed hopper A1, a feed hopper B4 and a mixing device 3, the left side of the mixing device 3 is connected with a feed hopper A1 through a feed delivery pipe 2, the upper part of the mixing device is provided with a feed hopper B4, the inside of the feed hopper is provided with a mixing blade 5, the right side of the feed hopper is also connected with a discharge pipe 6, the discharge pipe 6 is also provided with a discharge valve 7,
the carbonization device mainly comprises an outer frame tube 8, a core tube 9, a fixing device 10 and a gas storage tank 15, wherein the core tube 9 is arranged in the outer frame tube 8, the left side of the core tube 9 is connected with a mixing device 3 through a discharge tube 6, the right side of the core tube is connected with the gas storage tank 15 through a gas transmission tube 13, a gas pressure gauge 26 is arranged on the right side of the core tube 9, a gas exhaust tube 20 is connected below the core tube, a gas exhaust valve 21 is arranged on the gas exhaust tube 20, the fixing device 10 is fixed on the inner bottom surface of the outer frame tube 8,
the salt expansion measuring equipment mainly comprises a press machine 12, an upper refrigeration head 901, a lower refrigeration head 904, a vibrating plate 903, a permeable stone 902, a displacement meter 19, a water storage tower 18, a temperature sensor 22 and a moisture sensor 23, wherein the press machine 12 is arranged on a cross beam 11, the cross beam 11 is arranged on the outer top surface of an outer frame cylinder 8, the lower refrigeration head 904 is arranged on the inner bottom surface of a core cylinder 9, the vibrating plate 903 and the permeable stone 902 are sequentially arranged above the lower refrigeration head 904 from bottom to top, the upper refrigeration head 901 is arranged above the core cylinder 9 and connected with the press machine 12, the displacement meter 19 is fixedly arranged above the upper refrigeration head 901, the water storage tower 18 is connected with the core cylinder 9 through a water conveying pipe 17, a water flow valve 16 is further arranged on the water conveying pipe 17, the temperature sensor 22 and the moisture sensor 23 are fixed on the inner wall of the core cylinder 9, the press machine 12 is connected to a controller A27 through, the upper refrigeration head 901 and the lower refrigeration head 904 are connected to a controller B28 through data lines, the vibration plate 903 is connected to a controller C29 through data lines, the temperature sensor 22, the moisture sensor 23 and the displacement meter 19 are all connected with a data acquisition device 24 through data lines, and the data acquisition device 24 is connected to a computer 25 through data lines.
As an improvement of the invention, the core barrel 9 is made of corrosion-resistant rigid material, and the outer surface of the water storage tower 18 is marked with water level scale marks.
As an improvement of the invention, the temperature of the upper refrigeration head 901 and the lower refrigeration head 904 can be adjusted within the range of-40 ℃ to 40 ℃.
As another improvement of the invention, the rear barrel wall of the outer frame barrel 8 is connected with the barrel bottom through a hinge, the number of layers of the temperature sensor 22 and the moisture sensor 23 is determined by the height of the core barrel 9, and the distance between two adjacent layers of sensors is 5-10 cm.
The salinity swelling measuring device for the carbonized modified saline soil can be realized by the following steps of the operation method:
a. basic property test of saline soil: taking a site saline soil sample, and obtaining the physicochemical indexes of the saline soil through a physicochemical test, wherein the physicochemical indexes comprise soil property, water content, natural density, pH value, salt composition and content;
b. testing the salt expansion amount of the saline soil: calculating the mass of the required saline soil according to the natural density of the saline soil and the volume of the core barrel 9, weighing and pressing the mass into the core barrel 9, then pushing the core barrel 9 into the outer frame barrel 8 until the core barrel 9 is contacted with the fixing device 10, starting the operation controller A27, and enabling the press machine 12 to push the upper refrigerating head 901 to be contacted with the upper surface of the saline soil; the water immersion depth and the overlying load of the soil body are adjusted through the water flow valve 16 and the controller A27, the probe of the displacement meter 19 is adjusted to be in contact with the upper top cover of the outer frame cylinder 8, the rear side wall of the outer frame cylinder 8 is closed, and the temperature of the upper refrigerating head 901 and the temperature of the lower refrigerating head 904 are opened and adjusted through the controller B28; after the temperature is stable, reading numbers of the temperature sensor 22, the moisture sensor 23 and the displacement meter 19 of the saline soil under the action of the temperature gradient are tested;
c. mixing the saline soil and the alkaline material: weighing a certain amount of saline soil according to the natural density of the saline soil and the volume of a core barrel 9, putting the saline soil into a feed hopper A1, feeding the saline soil into a mixing device 3 through a feed delivery pipe 2, starting the mixing device 3, weighing a certain amount of alkaline curing agent and water according to the preset mixing amount of the curing agent and the water-cement ratio, putting the alkaline curing agent and the water into the mixing device 3 through a feed hopper B4, and uniformly mixing the mixture;
d. carbonizing and improving the saline soil mixture: opening the discharge valve 7 to enable the mixture to flow into the core barrel 9, starting the operation controller A27 to enable the press machine 12 to push the upper refrigeration head 901 to compact the saline soil to a preset density, checking and adjusting the core barrel 9 to ensure good air tightness, opening and adjusting the air delivery valve 14 to enable the air pressure gauge 26 to reach a preset air pressure, and finally closing the barrel wall of the outer frame barrel 8 to perform ventilation and carbonization;
e. and (3) testing the salt expansion amount of the carbonized saline soil: the water immersion depth and the overlying load of the soil body are adjusted through the water flow valve 16 and the controller A27, the displacement meter 19 is adjusted to enable the probe of the displacement meter to be in contact with the upper top cover of the outer frame cylinder 8, the controller B28 is started, the temperatures of the upper refrigerating head 901 and the lower refrigerating head 904 are adjusted, and after the temperatures are stable, the readings of the temperature sensor 22, the moisture sensor 23 and the displacement meter 19 of the carbonized saline soil under the action of the temperature gradient are tested;
f. analyzing the improvement effect of the solidified salinized soil: analyzing the salt swelling treatment effect through the salt swelling change rate, wherein the salt swelling rate calculation formula is as follows:
wherein x is the salt-swelling reduction rate of the saline soil before carbonization, delta h1The salt expansion (mm) before carbonization，Δh2The salt expansion (mm) is obtained after carbonization modification.
As an improvement of the invention, the salt in the saline soil mainly comprises soluble salts as main components, including chloride, sodium sulfate and magnesium sulfate, the alkaline curing agent is one or a combination of more of active magnesium oxide, quick lime or carbide slag, the ventilation air pressure is 25-300kPa, and the ventilation carbonization time is 3-24 hours.
As another improvement of the invention, the content of the alkaline solidifying agent and the aeration time are adjusted according to the soil property, the salt content and the aeration pressure, and when the content of the soil fine particles and the salt content are higher and the aeration pressure is lower, the content of the incorporated alkaline solidifying agent is higher and the aeration time is longer.
Example 1
If the salt content of the sample soil body is 3% and the salt content is mainly sodium chloride, the alkaline curing agent is a mixture of 80% active oxidation and 20% carbide slag, the mixing amount of the curing agent is 7.5%, the ventilation pressure is selected to be 100kPa, the ventilation time is selected to be 6h, and the temperature adjusting range of the upper and lower refrigerating heads can be controlled between-20 ℃ and 20 ℃; meanwhile, if the height of the core barrel 9 is 15cm, two layers of sensors are arranged at an interval of 5 cm.
Example 2
If the salt content of the sample soil body is between 3% and 6% and the salt content is mainly magnesium chloride and potassium chloride, the alkaline curing agent consists of 60% of active magnesium oxide, 20% of carbide slag and 20% of quicklime, the mixing amount of the curing agent is 10%, the ventilation pressure is 200kPa, the ventilation time is 12h, and the temperature adjusting range of the upper and lower refrigerating heads can be controlled between-30 ℃ and 30 ℃; meanwhile, if the height of the core barrel 9 is 15cm, two layers of sensors are arranged at an interval of 5 cm.
Example 3
If the salt content of the soil body is more than 5 percent and the salt content is mainly sodium chloride and potassium chloride, the alkaline curing agent is 60 percent of active magnesium oxide, 20 percent of carbide slag and 20 percent of quicklime, the mixing amount of the curing agent is 15 percent, the ventilation pressure is 300kPa, the ventilation time is 15 hours, and the temperature adjusting range of the upper and lower refrigerating heads can be controlled between minus 40 ℃ and 40 ℃; meanwhile, if the height of the core barrel 9 is 20cm, three layers of sensors are arranged at intervals of 5 cm.
Example 4
If the salt content of the soil body is 10 percent and the salt is mainly sodium sulfate or magnesium sulfate, the doping amount is 20 percent, the aeration pressure is 200kPa, the aeration time is 12 hours, and the temperature adjusting range of the upper and lower refrigerating heads can be controlled between minus 20 ℃ and 20 ℃; meanwhile, if the height of the core barrel 9 is 20cm, two layers of sensors are arranged at an interval of 7 cm.
Example 5
If the salt content of the soil body is between 8 percent and the salt content is mainly magnesium sulfate, the alkaline curing agent consists of 50 percent of active magnesium oxide, 25 percent of carbide slag and 25 percent of quicklime, the doping amount of the curing agent is 12 percent, the ventilation pressure is selected to be 100kPa, the ventilation time is selected to be 12 hours, and the temperature adjusting range of the upper and lower refrigerating heads can be controlled to be between 25 ℃ below zero and 25 ℃; meanwhile, if the height of the core barrel 9 is 25cm, three layers of sensors are arranged at intervals of 7 cm.
Example 6
If the salt content of the sample soil body is more than 5 percent and the salt content is mainly sodium sulfate or magnesium sulfate, the alkaline curing agent consists of 50 percent of active magnesium oxide, 25 percent of carbide slag and 25 percent of quicklime, the doping amount of the curing agent is 17.5 percent, the ventilation pressure is 200kPa, the ventilation time is 24 hours, and the temperature adjusting ranges of the upper and lower refrigerating heads can be controlled between minus 35 ℃ and 35 ℃; meanwhile, if the height of the core barrel 9 is 25cm, two layers of sensors are arranged at an interval of 10 cm.
The foregoing operational steps and embodiments have described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the specific embodiments described above, and that the above embodiments and descriptions are only for illustrating the principle of the present invention, and that various changes and modifications may be made without departing from the spirit and scope of the present invention, which fall within the scope of the claimed invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (7)
1. A device for measuring the salt expansion property of carbonized modified saline soil is characterized by comprising a curing agent mixing device, a carbonization device and a salt expansion property measuring device,
the curing agent mixing device comprises a feed hopper A, a feed hopper B and a mixing device, the left side of the mixing device is connected with the feed hopper A through a feed delivery pipe, the feed hopper B is arranged above the mixing device, a stirring blade is arranged in the mixing device, the right side of the mixing device is connected with a discharge pipe, a discharge valve is further arranged on the discharge pipe,
the carbonization device mainly comprises an outer frame cylinder, a core cylinder, a fixing device and a gas storage tank, wherein the core cylinder is arranged in the outer frame cylinder, the left side of the core cylinder is connected with a mixing device through a discharge pipe, the right side of the core cylinder is connected with the gas storage tank through a gas transmission pipe, a barometer is arranged on the right side of the core cylinder, a gas exhaust pipe is connected below the core cylinder, a gas exhaust valve is arranged on the gas exhaust pipe, the fixing device is fixed on the inner bottom surface of the outer frame cylinder,
the salt expansion measuring equipment mainly comprises a press machine, an upper refrigerating head, a lower refrigerating head, a vibrating plate, a permeable stone, a displacement meter, a water storage tower, a temperature sensor and a moisture sensor, wherein the press machine is arranged on a cross beam, the cross beam is arranged on the outer top surface of an outer frame barrel, the lower refrigerating head is arranged on the inner bottom surface of the core barrel, the vibrating plate and the permeable stone are sequentially arranged above the lower refrigerating head from bottom to top, the upper refrigerating head is arranged above the core barrel and connected with the press machine, the displacement meter is fixedly arranged above the upper refrigerating head, the water storage tower is connected with the core barrel through a water pipe, a water flow valve is arranged on the water pipe, the temperature sensor and the moisture sensor are fixed on the inner wall of the core barrel, the press machine is connected to a controller A through a data line, the upper refrigerating head and the lower refrigerating head are connected to a controller B through a data line, and the vibrating plate is, the temperature sensor, the moisture sensor and the displacement meter are all connected to data acquisition equipment through data lines, and the data acquisition equipment is connected to a computer through the data lines.
2. The apparatus as claimed in claim 1, wherein the core cylinder is made of corrosion-resistant rigid material, and the water tower has water level marks on its outer surface.
3. The apparatus of claim 1, wherein the temperature of the upper and lower cooling heads is adjustable between-40 ℃ and 40 ℃.
4. The apparatus as claimed in claim 1, wherein the wall of the outer casing is hinged to the frame, the number of the temperature sensor and the moisture sensor is determined according to the height of the core cylinder, and the distance between two adjacent sensors is 5-10 cm.
5. An operating method for the salination measurement of carbonized modified salinated soils as claimed in claim 1, comprising the steps of:
a. basic property test of saline soil: taking a site saline soil sample, and obtaining the physicochemical indexes of the saline soil through a physicochemical test, wherein the physicochemical indexes comprise soil property, water content, natural density, pH value, salt composition and content;
b. testing the salt expansion amount of the saline soil: according to the natural density of the saline soil and the volume of the core barrel, calculating the mass of the required saline soil, weighing and pressing the required saline soil into the core barrel, then pushing the core barrel into the outer frame barrel until the core barrel is contacted with the fixing device, starting the operation controller A, and enabling the pressing machine to push the upper refrigerating head to be contacted with the upper surface of the saline soil; the water immersion depth and the overlying load of the soil body are adjusted through a water flow valve and a controller A, a probe of a displacement meter is adjusted to be in contact with an upper top cover of the outer frame cylinder, the rear side wall of the outer frame cylinder is closed, and the temperature of an upper refrigerating head and the temperature of a lower refrigerating head are opened and adjusted through a controller B; after the temperature is stable, reading numbers of a temperature sensor, a moisture sensor and a displacement meter of the saline soil under the action of the temperature gradient are tested;
c. mixing the saline soil and the alkaline curing agent: weighing a certain amount of saline soil according to the natural density of the saline soil and the volume of the core barrel, putting the saline soil into a feed hopper A, putting the saline soil into a mixing device through a feed delivery pipe, starting the mixing device, weighing a certain amount of alkaline curing agent and water according to the preset mixing amount of the curing agent and the water-cement ratio, putting the alkaline curing agent and the water into the mixing device through a feed hopper B, and uniformly stirring the mixture;
d. carbonizing and improving the saline soil mixture: opening a discharge valve to enable the mixture to flow into the core barrel, starting an operation controller A to enable a press machine to push an upper refrigeration head to compact the saline soil to a preset density, checking the air tightness of the core barrel, opening and adjusting an air delivery valve to enable a barometer to reach a preset air pressure, finally closing the barrel wall of the outer frame barrel, and performing ventilation and carbonization;
e. and (3) testing the salt expansion amount of the carbonized saline soil: adjusting the immersion depth and the overlying load of the soil body through a water flow valve and a controller A, adjusting a displacement meter to enable a probe of the displacement meter to be in contact with an upper top cover of an outer frame cylinder, starting a controller B and adjusting the temperature of an upper refrigerating head and a lower refrigerating head, and testing the readings of a temperature sensor, a moisture sensor and the displacement meter of the carbonized saline soil under the action of temperature gradient after the temperature is stable;
f. analyzing the improvement effect of the solidified salinized soil: analyzing the salt swelling treatment effect through the salt swelling change rate, wherein the salt swelling rate calculation formula is as follows:
wherein x is the salt-swelling reduction rate of the saline soil before carbonization, delta h1The salt expansion (mm) before carbonization, Delta h2The salt expansion (mm) is obtained after carbonization modification.
6. The operation method as claimed in claim 5, wherein the salt in the saline soil is mainly soluble salts including chloride, sodium sulfate and magnesium sulfate, the alkaline curing agent is one or more of active magnesium oxide, quick lime or carbide slag, the aeration pressure is 25-300kPa, and the aeration carbonization time is 3-24 hours.
7. The method of claim 5, wherein the content of alkaline solidifying agent and the aeration time are adjusted according to the soil property, the salt content and the aeration pressure, and the higher the content of fine particles and the salt content of the soil body and the lower the aeration pressure, the more alkaline solidifying agent is mixed and the longer the aeration time.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113189308A (en) * | 2021-05-11 | 2021-07-30 | 西安建筑科技大学 | Deformation testing device for saline soil foundation |
| CN114184734A (en) * | 2021-10-11 | 2022-03-15 | 兰州大学 | Combined measuring device capable of distinguishing frozen swelling capacity and salt swelling capacity of saline soil |
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2020
- 2020-10-12 CN CN202011087456.8A patent/CN112098456A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113189308A (en) * | 2021-05-11 | 2021-07-30 | 西安建筑科技大学 | Deformation testing device for saline soil foundation |
| CN114184734A (en) * | 2021-10-11 | 2022-03-15 | 兰州大学 | Combined measuring device capable of distinguishing frozen swelling capacity and salt swelling capacity of saline soil |
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