A device and construction method for preparing roadbed soil based on silt carbonization solidification

Abstract

The application discloses a device and a construction method for preparing roadbed soil based on silt carbonization and solidification, and the device comprises a carbonization barrel arranged transversely, wherein the carbonization barrel is connected with a gas injection mechanism and a driving mechanism, both ends of the carbonization barrel are respectively provided with a discharging barrel cover and a feeding barrel cover, and the feeding barrel cover is provided with a feeding mechanism on one side; the feeding barrel cover is connected with the gas injection mechanism through an air inlet mechanism, the gas injection mechanism comprises a carbon dioxide storage tank and a pipeline communicated with the carbon dioxide storage tank, and the air inlet mechanism is connected with the pipeline. The device combines stirring and carbonization and simultaneously performs the stirring and the carbonization, under the combined action of the rotation of the carbonization barrel and the rotation of the propeller blade on the inner wall of the barrel, the mixture in the carbonization barrel is stirred uniformly, meanwhile, the carbon dioxide is more fully contacted with the mixture, the carbonization reaction is faster, the carbonization efficiency and the overall uniformity of the carbonization are improved, the strength of the silt is improved, the harmful substances of the silt can be solidified, and the carbonized soil material can be widely applied to engineering construction, and the diversity of the silt application is increased.

Description

Technical Field

[0001] This invention relates to an apparatus and construction method for preparing roadbed soil based on silt carbonization and solidification, belonging to the field of silt carbonization and solidification technology. Background Technology

[0002] Silt typically accumulates at the bottom of rivers, lakes, and ditches, and is one of the main causes of water pollution. When dredging is carried out, large amounts of silt are generated. Only a very small portion of this silt is used for land reclamation or reused as fertilizer; the majority is dumped into the ocean or buried on land, causing significant pollution to the surrounding environment.

[0003] Because silt has disadvantages such as high water content, low permeability, and low strength, it cannot meet the requirements of construction and needs to be solidified to improve its strength. Solidification involves adding a solidifying agent to the silt and mixing it evenly to change its properties and increase its strength. Common solidifying agents include cement, lime, and slag. Compared with traditional cement and lime solidification, carbonation-reinforced soil has the advantages of low energy consumption and rapid strength gain. Cement solidification is time-consuming and has a slow strength gain. It requires 28 days of curing to reach the strength to bear the load, and another 90 days of curing is needed to achieve the standard cured strength, resulting in slow construction progress. Carbonation-reinforced soil, on the other hand, can achieve the same strength as cement solidification after 28 days of curing in just a few hours.

[0004] However, carbonization solidification is mainly based on laboratory research, with limited field trials. Ensuring uniformity and integrity in the carbonization process while solidifying large volumes of sludge, and thus guaranteeing the effectiveness of the carbonization, is a pressing issue that needs to be addressed. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an apparatus and construction method for preparing roadbed soil based on silt carbonization and solidification. This method achieves on-site carbonization and solidification of silt by simultaneously stirring and carbonizing a mixture of silt, tert-butylmagnesium chloride, sodium bicarbonate (NaHCO3), and polyacrylamide (PAM), thereby improving the overall uniformity and efficiency of carbonization. This not only increases the strength of the silt but also solidifies harmful substances such as heavy metal ions. The carbonized soil can be widely used in engineering construction, increasing the versatility of silt applications.

[0006] The first objective of this invention is to provide an apparatus for preparing roadbed soil based on sludge carbonization and solidification, comprising a horizontally placed carbonization barrel, the carbonization barrel being connected to an air jetting mechanism and a drive mechanism for rotating the carbonization barrel, wherein a detachable discharge barrel cover and a feed barrel cover are respectively provided at both ends of the carbonization barrel, and a feeding mechanism is provided on one side of the feed barrel cover; the feed barrel cover is connected to the air jetting mechanism through an air intake mechanism, the air jetting mechanism including a carbon dioxide storage tank and a pipe connected thereto, the air intake mechanism being connected to the pipe; the feeding mechanism including a conveyor belt and a chute located on one side of the conveyor belt, the chute being located on one side of the feed barrel cover, the conveyor belt being used to deliver material through the conveyor belt and the chute into the carbonization barrel.

[0007] In one embodiment of the present invention, the driving mechanism is mounted on a support and includes a motor, a gear and a roller. The motor is connected to the roller through the gear and is used to drive the roller to rotate. The carbonization barrel is mounted on the roller and abuts against the roller.

[0008] In one embodiment of the present invention, an air inlet is provided at the center of the feed barrel cover, and the air inlet mechanism is connected to the air inlet. The feed barrel cover is also provided with an exhaust port, and the exhaust port is provided with a valve for opening / closing the exhaust port. The feed barrel cover is a semi-open structure, including an upper barrel cover and a lower barrel cover. The lower barrel cover is fixedly connected to the barrel body of the carbonization barrel. The upper barrel cover and the lower barrel cover are connected by a hinge so that the upper barrel cover can be opened. Several buckles are provided at the edges of the upper barrel cover of the feed barrel cover and the discharge barrel cover. The upper barrel cover of the feed barrel cover and the discharge barrel cover are fastened to the barrel body of the carbonization barrel by the buckles. A sealing ring is provided at the contact point between the feed barrel cover and the discharge barrel cover and the barrel body of the carbonization barrel.

[0009] In one embodiment of the present invention, the air intake mechanism includes an air vent pipe and a bearing sleeved outside the air vent pipe and fixedly connected to the air vent pipe. The bearing is disposed inside the air inlet of the feed barrel cover and fixedly connected to the feed barrel cover. The air vent pipe is connected to a pipeline.

[0010] In one embodiment of the present invention, the slide is curved, the top of the slide is located on one side of the conveyor belt and is used to carry the soil transported by the conveyor belt, and the bottom of the slide can extend into the carbonization barrel.

[0011] In one embodiment of the present invention, a propeller blade is provided inside the carbonization barrel, and the propeller blade is fixedly connected to the inner wall of the carbonization barrel, and the carbonization barrel drives the propeller blade to rotate together.

[0012] In one embodiment of the present invention, the carbonization barrel has an inner diameter of 1-2m, a barrel length of 1.5-2.5m, and a wall thickness of 2-4cm; the propeller blade has a blade width of 20-25cm, an angle of 45-60 degrees with the inner wall of the carbonization barrel, and the angle is biased towards the discharge barrel cover.

[0013] In one embodiment of the present invention, a pressure valve is provided on the pipeline, and the pipeline is a flexible hose.

[0014] In one embodiment of the present invention, the diameter of the vent pipe is 2-3 cm, one end of which extends 4-6 cm out of the outside of the carbonization barrel and the other end extends 4-6 cm into the inside of the carbonization barrel. The wall thickness of the vent pipe is 1-3 mm, and filter screens are provided at both ends of the vent pipe.

[0015] The second objective of this invention is to provide a construction method for preparing subgrade soil based on silt carbonization and solidification, which utilizes the aforementioned apparatus for preparing subgrade soil based on silt carbonization and solidification, and includes the following steps:

[0016] S1. The lake bottom silt is processed to a moisture content of 20%-30% by squeezing and drying. Sufficient carbon dioxide, tert-butyl magnesium chloride, sodium bicarbonate, polyacrylamide, and pipelines are prepared.

[0017] S2. Open the feed tank cover, extend the slide of the feeding mechanism into the carbonization tank, and add sludge, tert-butyl magnesium chloride, sodium bicarbonate and polyacrylamide in a ratio of 60-80:5-15:3-10:0.0-0.5 to the carbonization tank via conveyor belt until the tank volume is 60%-80%. Close the feed tank cover and tighten the buckle.

[0018] S3. Connect one end of the pipe to the vent pipe and the other end to the carbon dioxide storage tank through the pressure valve. After the connection is completed, check the connection to ensure that the connection is tight and leak-proof.

[0019] S4. Open the pressure valve, control the pressure at 200-1000Kpa, spray carbon dioxide into the carbonization barrel, open the valve at the exhaust port to discharge the excess air in the carbonization barrel, close the valve at the exhaust port, and start the carbonization and solidification of the sludge.

[0020] S5. Turn on the motor. The motor drives the roller to rotate, which in turn drives the carbonization barrel to rotate. During the rotation of the carbonization barrel, the mixture is fully mixed due to gravity and the rotation of the propeller blades inside the barrel.

[0021] S6. After carbonization for 1-3 hours, close the pressure valve, open the valve at the vent hole, remove the carbon dioxide from the carbonization barrel, disconnect the pipe connected to the vent pipe, and open the buckle of the discharge barrel cover to open the discharge barrel cover. After the soil in the barrel is emptied, repeat steps S1-S6 to start the next carbonization and solidification of the sludge.

[0022] S7. Transport the carbonized soil to the construction site to be used as roadbed material.

[0023] Beneficial effects

[0024] 1. Compared to traditional soil carbonization methods that involve first mixing the soil mixture thoroughly before introducing carbon dioxide, this invention combines mixing and carbonization simultaneously. Carbon dioxide is introduced into the carbonization tank, and the combined action of the rotating tank and the rotating propeller blades inside ensures thorough mixing of the mixture. This also allows for more complete contact between the carbon dioxide and the mixture, resulting in a faster carbonization reaction and improved carbonization efficiency and overall uniformity.

[0025] 2. This invention achieves on-site carbonization and solidification of sludge. A mixture of sludge, tert-butylmagnesium chloride, sodium bicarbonate (NaHCO3), and polyacrylamide (PAM) is simultaneously stirred and carbonized, improving the overall uniformity and efficiency of carbonization. This not only increases the strength of the sludge but also solidifies harmful substances such as heavy metal ions. The carbonized material can be widely used in engineering construction, increasing the versatility of sludge applications. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the device for preparing roadbed soil based on silt carbonization and solidification according to the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of the feed hopper cover and the discharge hopper cover of the present invention.

[0029] Figure 3 This is a schematic diagram of the intake mechanism of the present invention;

[0030] Figure 4 This is a schematic diagram of the bearing structure of the present invention;

[0031] Figure 5 This is a front view of the propeller blade of the present invention;

[0032] Figure 6 This is a cross-sectional view of the carbonization barrel of the present invention;

[0033] Figure 7 This is a perspective view of the propeller blade of the present invention;

[0034] Figure 8 The figure shows the test results of unconfined compressive strength at different carbonization times in Example 5 of the present invention.

[0035] Figure 9 The figure shows the test results of unconfined compressive strength of magnesium tert-butyl greening with different dosages in Example 6 of the present invention.

[0036] In the diagram: 1. Carbonization barrel; 2. Discharge barrel cover; 3. Roller; 4. Support; 5. Motor; 6. Gear; 7. Air intake mechanism; 8. Pipe; 9. Conveyor belt; 10. Pressure valve; 11. Carbon dioxide storage tank; 12. Slide rail; 13. Feed barrel cover; 14. Exhaust port; 101. Air inlet; 102. Buckle; 103. Hinge; 201. Vent pipe; 202. Bearing; 301. Propeller blade. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] Example 1

[0041] like Figure 1-7As shown, this embodiment provides an apparatus for preparing roadbed soil based on sludge carbonization and solidification, including a horizontally placed carbonization barrel 1. The carbonization barrel 1 is connected to an air jet mechanism and a drive mechanism for driving the carbonization barrel 1 to rotate. The two ends of the carbonization barrel 1 are respectively provided with a detachable discharge barrel cover 2 and a feed barrel cover 13. A feeding mechanism is provided on one side of the feed barrel cover 13. The feed barrel cover 13 is connected to the air jet mechanism through an air intake mechanism 7. The air jet mechanism includes a carbon dioxide storage tank 12 and a pipe 8 connected to it. The air intake mechanism 7 is connected to the pipe 8. The feeding mechanism includes a conveyor belt 9 and a slide 12 located on one side of the conveyor belt 9. The slide 12 is located on one side of the feed barrel cover 13. The conveyor belt 9 is used to send the material through the conveyor belt 9 and the slide 12 into the carbonization barrel 1.

[0042] Optionally, the drive mechanism is mounted on the support 4. The drive mechanism includes a motor 5, a gear 6, and a roller 3. The motor 5 is connected to the roller 3 via the gear 6, and the motor 5 drives the roller 3 to rotate. The carbonization barrel 1 is mounted on the roller 3 and abuts against the roller 3. The motor 5 drives the roller 3 to rotate via the gear 6, and the roller 3 drives the carbonization barrel 1 to rotate.

[0043] Optionally, the feed barrel cover 13 has an air inlet 101 at its center, and the air intake mechanism 7 is connected to the air inlet 101. The feed barrel cover 13 also has an exhaust vent 14. Preferably, the exhaust vent 14 has an inner diameter of 1-3 cm and a thickness of 2-4 mm, and is equipped with a valve for opening / closing the exhaust vent 14. The feed barrel cover 13 has a semi-open structure, including an upper part of the cover and a lower part of the cover. The lower part of the cover is fixedly connected to the body of the carbonization barrel 1. Some of the barrel lids are connected by hinges 103 so that the upper part of the barrel lid can be opened for the feeding mechanism to transport sludge into the barrel; the upper part of the feeding barrel lid 13 and the edge of the discharging barrel lid 2 are provided with several buckles 102. The upper part of the feeding barrel lid 13 and the discharging barrel lid 2 are fastened to the barrel body of the carbonization barrel 1 by the buckles 102. A sealing ring is provided at the contact point between the feeding barrel lid 13 and the discharging barrel lid 2 and the barrel body of the carbonization barrel 1 to ensure the airtightness of the carbonization barrel 1 during the carbonization process.

[0044] Optionally, the air intake mechanism 7 includes an air vent pipe 201 and a bearing 202 sleeved on and fixedly connected to the air vent pipe 201. The bearing 202 is disposed inside the air inlet hole 101 of the feed barrel cover 13 and fixedly connected to the feed barrel cover 13. The air vent pipe 201 is connected to the pipe 8. The outer ring of the bearing 202 is fixed to the center of the feed barrel cover 13, and the inner ring of the bearing 202 matches the air vent pipe 201. Due to the function of the bearing 202, the pipe 8 will not rotate when the carbonization barrel 1 rotates during the carbonization process, thus avoiding the pipe 8 from getting tangled in the carbonization barrel 1 and causing the carbonization process to stop.

[0045] Optionally, the slide 12 has an arc, with its top located on one side of the conveyor belt 9 to carry the soil transported by the conveyor belt 9, and its bottom extending into the carbonization barrel 1. The slide 12 transports the soil transported by the conveyor belt 9 through its upper surface into the carbonization barrel 1.

[0046] Optionally, a propeller blade 301 is provided inside the carbonization barrel 1, and the propeller blade 301 is fixedly connected to the inner wall of the carbonization barrel 1. Preferably, the carbonization barrel 1 is a cylindrical barrel. According to actual needs, the inner diameter of the carbonization barrel 1 can be set to 1-2m, the barrel length can be set to 1.5-2.5m, and the wall thickness can be set to 2-4cm. The blade width of the propeller blade 301 can be set to 20-25cm, and the angle with the inner wall of the carbonization barrel 1 is 45-60 degrees, with the angle biased towards the discharge barrel cover 2. The pitch of the propeller blade 301 is preferably 0.5m. The carbonization barrel 1 drives the propeller blade 301 to rotate together, so that the propeller blade 301 can stir the mixture in the carbonization barrel 1 evenly, achieving a better carbonization effect, and can also send the soil in the carbonization barrel 1 after carbonization to the discharge barrel cover 2 for convenient discharge.

[0047] Optionally, a pressure valve 10 is provided on the pipe 8. Preferably, the pipe 8 is a flexible hose, preferably made of plastic. The diameter of the vent pipe 201 is 2-3 cm, with one end extending 4-6 cm beyond the outside of the carbonization barrel 1 and the other end extending 4-6 cm into the inside of the carbonization barrel 1. The wall thickness of the vent pipe 201 is 1-3 mm. Filter screens are provided at both ends of the vent pipe 201, and the pressure valve 10 controls the air jet pressure to 200 kPa to prevent soil particles from clogging the vent pipe 201 during the carbonization process.

[0048] Example 2

[0049] This embodiment provides a construction method for preparing subgrade soil based on silt carbonization and solidification. The method uses the apparatus for preparing subgrade soil based on silt carbonization and solidification provided in Embodiment 1, and includes the following steps:

[0050] S1. The lake bottom silt is processed to a moisture content of 20%-30% by squeezing and drying. Sufficient carbon dioxide, tert-butyl magnesium chloride, sodium bicarbonate (NaHCO3), polyacrylamide (PAM) and pipeline 8 are prepared.

[0051] S2. Open the feed tank cover 13, extend the slide 12 of the feeding mechanism into the carbonization tank 1, and add sludge, tert-butyl magnesium chloride, sodium bicarbonate (NaHCO3), and polyacrylamide (PAM) into the carbonization tank 1 in a ratio of 60-70:5-15:5-15:0.0-0.5 via the conveyor belt 9 until the tank volume is 60%-80%. Close the feed tank cover 13 and tighten the buckle 102.

[0052] S3. Connect one end of pipe 8 to vent pipe 201, and connect the other end to carbon dioxide storage tank 11 through pressure valve 10. After the connection is completed, check the connection to ensure that the connection is tight and leak-proof.

[0053] S4. Open pressure valve 10, control the pressure at around 200-1000Kpa, spray carbon dioxide into carbonization barrel 1, open the valve at exhaust port 14 to discharge excess air from carbonization barrel 1, close the valve at exhaust port 14, and begin carbonization and solidification of sludge.

[0054] S5. Turn on motor 5. Motor 2 drives roller 3 to rotate, which in turn drives carbonization barrel 1 to rotate. During the rotation of carbonization barrel 1, the mixture is fully mixed due to gravity and the rotation of propeller blade 301 inside the barrel.

[0055] S6. After carbonization for 1-3 hours, close the pressure valve 10, open the valve at the exhaust port 14 to remove the carbon dioxide from the carbonization barrel 1, then disconnect the pipe 8 connected to the ventilation pipe 201, and open the buckle 102 of the discharge barrel cover 2 to open the discharge barrel cover 2. After the soil in the barrel is emptied, repeat steps S1-S6 to start the next carbonization and solidification of the sludge.

[0056] S7. Transport the carbonized soil to the construction site to be used as roadbed material.

[0057] Compared to traditional soil carbonization methods that involve first mixing the soil mixture thoroughly before introducing carbon dioxide, this invention combines mixing and carbonization simultaneously. Carbon dioxide is introduced into the carbonization tank, and the combined action of the rotating tank and the rotating propeller blades inside ensures thorough mixing of the mixture. This also allows for more complete contact between the carbon dioxide and the mixture, resulting in a faster carbonization reaction and improved carbonization efficiency and overall uniformity.

[0058] Example 3

[0059] This embodiment is an indoor test. Taking Taihu Lake silt as an example, it mainly analyzes the liquid limit, plastic limit, unconfined compressive strength and bearing ratio of the silt after carbonization, and explores the feasibility of using silt as roadbed material.

[0060] Taihu Lake silt was dried and pulverized. The silt, tert-butylmagnesium chloride, sodium bicarbonate (NaHCO3), and polyacrylamide (PAM) were mixed evenly in a ratio of 87.5:7:5:0.5. The liquid and plastic limits of the mixture were measured. Water was added until the moisture content of the mixture reached 28%, and the mixture was stirred evenly. The mixture was placed in a sealed container, and carbonation was carried out by introducing carbon dioxide at a pressure of 200 kPa for 1 hour. The carbonized soil was then subjected to unconfined compressive strength and bearing ratio tests.

[0061] The tests showed that the liquid limit of the sludge was 24.44% and the plastic limit was 49.44%; the plastic limit of the mixture was 28.78% and the liquid limit was 45.18%. The plastic limit significantly increased, while the liquid limit significantly decreased. The unconfined compressive strength of the sludge was 170 kPa, and the unconfined compressive strength of the mixture after carbonization was 2.15 MPa, showing a significant increase. The load-bearing ratio of the mixture after carbonization was 4.48%.

[0062] The liquid limit, unconfined compressive strength, and bearing capacity ratio described above meet the requirements for roadbed materials.

[0063] Example 4

[0064] Comparing cement as a curing agent for solidifying silt, Taihu Lake silt was dried and pulverized, then mixed with 7% cement to prepare a mixture with a moisture content of 28%. This mixture was divided into four portions and cured under standard curing conditions for 0, 7, 14, and 28 days, respectively. The unconfined compressive strengths of the samples after different curing days were measured to be 315.6 kPa, 523.4 kPa, 849.2 kPa, and 1120.3 kPa, respectively. With increasing curing time, the unconfined compressive strength of the cement-cured silt gradually increased. In Example 4, after 1 hour of carbonation, the unconfined compressive strength of the mixture was 2.15 MPa, significantly higher than the strength of the cement-cured silt after 28 days of curing. Furthermore, the method in Example 3 requires no curing, has a shorter cycle, and is more efficient.

[0065] Example 5

[0066] The mixture was prepared according to the proportions in Example 3, divided into five groups, and carbonized for 0, 1, 2, 3, and 4 hours respectively. The unconfined compressive strength of each group was measured, and the test results are as follows: Figure 8 As shown.

[0067] The results showed that the unconfined compressive strength (UCS) of the mixture was significantly improved after carbonization. With the increase of carbonization time, the unconfined compressive strength of the mixture first increased and then gradually decreased.

[0068] Example 6

[0069] Taihu Lake silt was dried and pulverized, and tert-butyl magnesium chloride (3%, 5%, 7%, and 9%) was added to each mixture. Then, caustic alkali with the same dosage as tert-butyl magnesium chloride was added to each mixture. Finally, 0.5% PAM was added to each mixture. The mixtures were stirred evenly, and water was added to a moisture content of 28%. The mixtures were carbonized for 1 hour, and their unconfined compressive strength was measured. The results are as follows: Figure 9 As shown.

[0070] The results showed that the unconfined compressive strength of the carbonized sludge increased with the increase of tert-butyl magnesium chloride content. The unconfined compressive strength was 745.8 kPa when the tert-butyl magnesium chloride content was 3%, 1448.7 kPa when it was 5%, 2154.6 kPa when it was 7%, and 3059.1 kPa when it was 9%.

[0071] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An apparatus for preparing subgrade soil based on carbonization solidification of sludge, characterized by comprising: The application relates to a device for preparing roadbed soil based on silt carbonization and solidification, which comprises a transversely arranged carbonization barrel, a jet mechanism connected with the carbonization barrel and a driving mechanism for driving the carbonization barrel to rotate, detachable discharge barrel covers and feeding barrel covers arranged at two ends of the carbonization barrel respectively, a feeding mechanism arranged at one side of the feeding barrel cover, a jet mechanism connected with the feeding barrel cover through an air inlet mechanism, a carbon dioxide storage tank and a pipeline communicated with the carbon dioxide storage tank, the air inlet mechanism being connected with the pipeline, a conveying belt and a slide arranged at one side of the conveying belt, the slide being arranged at one side of the feeding barrel cover, the conveying belt being used for conveying materials into the carbonization barrel through the conveying belt and the slide, the driving mechanism being arranged on a support, the driving mechanism comprising a motor, a gear and a roller, the motor being connected with the roller through the gear, the motor being used for driving the roller to rotate, the carbonization barrel being arranged on the roller and abutting against the roller, a gas inlet hole arranged at the center of the feeding barrel cover, the air inlet mechanism being connected with the gas inlet hole, the feeding barrel cover being further provided with a gas outlet hole, the gas outlet hole being provided with a valve for opening / closing the gas outlet hole, the feeding barrel cover being a semi-open structure and comprising an upper half barrel cover and a lower half barrel cover, the lower half barrel cover being fixedly connected with a barrel body of the carbonization barrel, the upper half barrel cover and the lower half barrel cover being connected through a hinge, so that the upper half barrel cover can be opened, a plurality of buckles being arranged at edge positions of the upper half barrel cover of the feeding barrel cover and the discharge barrel cover, the upper half barrel cover of the feeding barrel cover and the discharge barrel cover being fastened with the barrel body of the carbonization barrel through the buckles, sealing rings being arranged at positions where the feeding barrel cover and the discharge barrel cover are attached to the barrel body of the carbonization barrel, the air inlet mechanism comprising an air pipe and a bearing sleeved outside the air pipe and fixedly connected with the air pipe, the bearing being arranged in the gas inlet hole of the feeding barrel cover and fixedly connected with the feeding barrel cover, the air pipe being connected with the pipeline, the slide having an arc, the top of the slide being arranged at one side of the conveying belt and used for bearing the earth materials conveyed by the conveying belt, the bottom of the slide being capable of extending into the carbonization barrel, the carbonization barrel being provided with a spiral blade, the spiral blade being fixedly connected with the inner wall of the carbonization barrel, the carbonization barrel driving the spiral blade to rotate together, the carbonization barrel having an inner diameter of 1-2 m, a barrel length of 1.5-2.5 m and a wall thickness of 2-4 cm, the spiral blade having a blade width of 20-25 cm and an angle of 45-60 degrees with the inner wall of the carbonization barrel, the angle being inclined to the discharge barrel cover, the pipeline being a soft pipe and being provided with a pressure valve, the air pipe having a diameter of 2-3 cm, one end of the air pipe extending outside the carbonization barrel by 4-6 cm, the other end of the air pipe extending into the carbonization barrel by 4-6 cm, the wall thickness of the air pipe being 1-3 mm, and the air pipe being provided with a filter screen at both ends, and the device for preparing roadbed soil based on silt carbonization and solidification is applied to the following steps. S1, the lake bottom silt is treated by extrusion and airing to have a water content of 20%-30%, sufficient carbon dioxide, tertiary butyl magnesium chloride, sodium bicarbonate, polyacrylamide and a pipeline are prepared. ​ ​ ​ ​ 2. The apparatus for preparing subgrade soil based on carbonization and solidification of sludge according to claim 1, characterized in that, ​ 3. The apparatus for preparing subgrade soil based on carbonization and solidification of sludge according to claim 2, characterized in that, ​ 4. The apparatus for preparing subgrade soil based on carbonization and solidification of sludge according to claim 3, characterized in that, ​ 5. A construction method for preparing subgrade soil based on carbonization solidification of sludge, characterized by, ​ ​ S2, open the feed tank cover, the slide of the feeding mechanism into the carbonization barrel, sludge, tertiary butyl magnesium chloride, sodium bicarbonate, polyacrylamide into the carbonization barrel by the proportion of 60-80:5-15:3-10:0.0-0.5 through the conveyor to 60%-80% of the volume of the barrel, close the feed tank cover, clamping buckle; S3, one end of the pipeline is connected with the air pipe, and the other end is connected with the carbon dioxide storage tank through the pressure valve. After the connection is completed, check the connection port to ensure that the connection is tight and there is no air leakage; S4, open the pressure valve, control the pressure at 200-1000Kpa, inject carbon dioxide into the carbonization barrel, open the valve at the exhaust hole, exhaust the excess air in the carbonization barrel, close the valve at the exhaust hole, start the carbonization and solidification of the sludge; S5, open the motor, the motor drives the roller to rotate and drives the carbonization barrel to rotate. During the rotation of the carbonization barrel, the mixture is fully mixed due to the gravity and the rotation of the propeller blade in the barrel; S6, after carbonization for 1-3 hours, close the pressure valve, open the valve at the exhaust hole, remove the carbon dioxide in the carbonization barrel, remove the pipeline connected to the air pipe, open the buckle of the discharge tank cover to open the discharge tank cover, when the soil in the barrel is empty, repeat steps S1-S6 to start the next carbonization and solidification of the sludge; S7, the carbonized soil is transported to the construction site as roadbed material.

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