A device for constructing a barrier to contaminated sites

Abstract

The present invention belongs to the field of construction of structures in contaminated sites, and discloses a construction device for contaminated site barrier, which can achieve rapid movement, and the device does not need to be disassembled to enter and exit the site, thereby improving the construction efficiency of the barrier. The construction device includes a walking base, a traction arm, a stirring tool assembly, a storage unit, a monitoring unit and a control unit; wherein the stirring tool assembly is connected to the base through the traction arm, and the traction arm can drive the stirring tool assembly to rotate around the axis of the traction arm; the storage unit is connected to the pipeline assembly; one end of the pipeline assembly is fixed on the stirring tool assembly; the monitoring unit is used to monitor the pH value and conductivity of the barrier material during the stirring process of the stirring tool assembly; and the control unit is used to control the working state of the storage unit.

Description

Technical Field

[0001] The invention belongs to the field of construction of structures in contaminated sites, and in particular, relates to a construction device for a contaminated site isolation barrier. Background Art

[0002] Soil and groundwater contamination at contaminated sites will increase public health risks and damage the ecosystem. Green and low-carbon contaminated site management is essential for protecting the environment, maintaining public health and promoting sustainable development. Through scientific remediation and management measures, the harm of pollutants to humans and ecosystems can be reduced and the utilization value of land can be restored.

[0003] Contaminated site barrier can effectively control the migration and diffusion of pollutants in soil and groundwater, and is one of the commonly used contaminated site remediation technologies. Barriers usually use highly alkaline cementitious materials such as cement to treat the in-situ soil, reduce the permeability coefficient of the in-situ soil, and thus control the migration of pollutants to the environment outside the site.

[0004] At present, the construction of barrier barriers is mainly based on the process and equipment of backfilling barrier materials after trenching with engineering excavators, and mixing pile machines to mix in-situ soil and cementitious materials. However, these construction processes and the equipment used are often heavy equipment and occupy a large area, so there are many disadvantages in the construction of industrial parks and on-site enterprises. Therefore, it is necessary to further develop barrier construction equipment with low headroom, good mobility and high construction quality. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a construction device for a contaminated site barrier in view of the deficiencies in the prior art, which can achieve rapid movement and does not need to be disassembled when entering and leaving the site, thereby improving the construction efficiency of the barrier.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] A device for constructing a barrier to contaminated sites, comprising a walking base, a traction arm, a stirring tool assembly, a material storage unit, a monitoring unit and a control unit; wherein the stirring tool assembly is connected to the base via the traction arm, and the traction arm can drive the stirring tool assembly to rotate around the axis of the traction arm; the material storage unit is connected to a pipeline assembly; one end of the pipeline assembly is fixed on the stirring tool assembly; the monitoring unit is used to monitor the pH value and conductivity of the barrier material during the stirring process of the stirring tool assembly; and the control unit is used to control the working state of the material storage unit.

[0008] As a preferred example, the stirring tool assembly includes a stirring chain, a stirring blade, a bracket, a chain guide wheel and a power device; the chain guide wheels are two and are installed at both ends of the bracket; the stirring chain is sleeved on the two chain guide wheels; the power device is connected to at least one chain guide wheel to drive the chain guide wheel to rotate; the bracket and the traction arm are fixedly connected; the stirring blade is fixedly connected to the stirring chain.

[0009] As a preferred example, the two chain guide wheels are installed at the top and bottom ends of the bracket; the stirring blades are evenly distributed along the circumference of the stirring chain, and the distance between two adjacent stirring blades is 1 to 3 meters.

[0010] As a preferred example, the material storage unit includes a filler storage tank, a compressed air storage tank and a carbon dioxide storage tank; the pipeline assembly includes a first transmission pipeline and a second transmission pipeline, and the first transmission pipeline and the second transmission pipeline are connected to the bracket; the filler storage tank is connected to the first transmission pipeline through a first connecting pipe and a second connecting pipe connected to the first connecting pipe, and a first valve is provided in the first connecting pipe, and a second valve is provided in the second connecting pipe; the compressed air storage tank is connected to the first transmission pipeline through a third connecting pipe and a second connecting pipe connected to the third connecting pipe, and a third valve is provided in the third connecting pipe; the first connecting pipe, the second connecting pipe and the third connecting pipe are connected by a three-way valve; the carbon dioxide storage tank is connected to the second transmission pipeline through a fourth connecting pipe, and a fourth valve is provided in the fourth connecting pipe.

[0011] As a preferred example, the device also includes a distributed sensor, which is fixedly connected to the bracket; it also includes a data display terminal, which is used to display the pH value and conductivity information monitored by the distributed sensor; the monitoring unit is respectively connected to the distributed sensor and the data display terminal.

[0012] As a preferred example, the control unit is connected to the first valve, the second valve, the third valve, and the fourth valve respectively.

[0013] As a preferred example, the second transmission pipeline includes a second transmission main pipeline, a second transmission branch pipeline and a carbon dioxide injector, the second transmission branch pipeline is horizontal, distributed vertically, and connected to the second transmission main pipeline; the carbon dioxide injector is connected and connected to the second transmission branch pipeline, and a carbon dioxide injection switch is provided in the second transmission branch pipeline; the carbon dioxide injector and the carbon dioxide injection switch are respectively connected to the control unit.

[0014] As a preferred example, the overlapping length of adjacent carbon dioxide injectors is 0.1 to 0.3 times the length of the carbon dioxide injector; the length of the carbon dioxide injector is 1 to 5 m; and the injection surface of the carbon dioxide injector is provided with injection holes of different diameters.

[0015] As a preferred example, an anti-clogging nozzle is provided at the end of the first transmission pipeline, and the anti-clogging nozzle includes a nozzle tube, a nozzle, a separating piston and a guide rail; the nozzle tube is connected to the end of the first transmission pipeline, the top of the guide rail is fixedly connected to the inner wall of the nozzle tube, a limiting piece is provided at the bottom of the guide rail, the separating piston is mounted on the guide rail and can move up and down along the guide rail; the nozzle is located on the nozzle tube; when the separating piston is located at the bottom of the guide rail, the nozzle is located above the separating piston.

[0016] As a preferred example, the number of the nozzles is 3 to 6 and they are distributed along the circumference of the nozzle tube.

[0017] Compared with the prior art, the construction equipment for contaminated site barrier of the present invention can be moved to improve the construction efficiency of the barrier. The construction equipment includes a walking base, a traction arm, a stirring tool assembly, a material storage unit, a monitoring unit and a control unit. The construction equipment occupies a small area and does not require on-site installation. Construction can start as soon as the equipment arrives at the site, so it can effectively increase construction efficiency and is fully suitable for sites with limited working areas. In addition, when the construction equipment is not in working state, the stirring tool assembly can be fixed in the horizontal direction by the traction arm and moved with the base without disassembling the stirring tool assembly, and has good transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the device in the embodiment of the present invention;

[0019] Figure 2 It is a schematic diagram of the left side structure of the stirring tool assembly and the traction arm in an embodiment of the present invention;

[0020] Figure 3 It is a schematic diagram of the right side structure of the stirring tool assembly and the traction arm in an embodiment of the present invention;

[0021] Figure 4 It is a front view of the stirring knife assembly and the traction arm in the embodiment of the present invention;

[0022] Figure 5 is a front view of a bracket according to an embodiment of the present invention,

[0023] Figure 6 is a side view of a bracket according to an embodiment of the present invention;

[0024] Figure 7 is an axial cross-sectional view of an anti-clogging nozzle in an open state according to an embodiment of the present invention,

[0025] Figure 8 It is an axial cross-sectional view of an anti-clogging nozzle in a closed state in an embodiment of the present invention;

[0026] Fig. 9 for Figure 7Sectional view along section A-A';

[0027] Fig.10 is a schematic diagram of a carbon dioxide injector in an embodiment of the present invention;

[0028] Fig.11 It is a schematic diagram of the placement state of the stirring knife assembly in a non-working state according to an embodiment of the present invention;

[0029] Fig.12 Graphs showing sample permeability coefficients of barrier structures constructed in the embodiments and comparative examples of the present invention.

[0030] The figure includes: base 1, traction arm 2, traction arm axis 201, stirring chain 301, stirring blade 3011, bracket 302, chain guide wheel 303, power device 304, storage unit 4, filler storage tank 401, first valve 4011, second valve 4012, first transmission pipeline 4013, three-way valve 4014, compressed air storage tank 402, third valve 4021, carbon dioxide storage tank 403, fourth valve 4031, second transmission pipeline 4032, carbon dioxide injector 40321, injection hole 403211, carbon dioxide injection switch 40322, monitoring unit 5, distributed sensor 501, data display terminal 502, control unit 6, control switch 601, stratum soil 7, ground 701, nozzle tube 901, nozzle 902, separation piston 903, guide rail 904. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described in detail below.

[0032] like Figure 1 and Fig.11 As shown, an embodiment of the present invention is a device for constructing a barrier for contaminated sites, comprising a walking base 1, a traction arm 2, a stirring tool assembly, a storage unit 4, a monitoring unit 5 and a control unit 6. The stirring tool assembly is connected to the base 1 through the traction arm 2, and the traction arm 2 can drive the stirring tool assembly to rotate around the traction arm axis 201. The storage unit 4 is connected to the pipeline assembly. One end of the pipeline assembly is fixed on the stirring tool assembly. The monitoring unit 5 is used to monitor the pH value and conductivity of the barrier material during the stirring process of the stirring tool assembly. The control unit 6 is used to control the working state of the storage unit 4.

[0033] In the embodiment, the base 1 is provided with a walking mechanism and can walk on the ground 701. According to the position of the barrier, the construction equipment is moved to the designated position by the walking mechanism. The base 1 occupies a small area. The traction arm 2 controls the rotation and operation of the stirring tool assembly. Before walking, the traction arm 2 drives the stirring tool assembly to rotate so that the stirring tool assembly is in a horizontal state, so that the base 1 walks normally. When the base 1 stops walking and builds a barrier in the formation soil 7, the traction arm 2 drives the stirring tool assembly to rotate so that the stirring tool assembly is in a vertical state, and the bottom of the stirring tool assembly is located in the formation soil 7.

[0034] The material storage unit 4 is connected to the pipeline assembly. One end of the pipeline assembly is fixed on the stirring tool assembly. The material storage unit 4 transports slurry and gas into the stirred soil through the pipeline assembly to achieve the construction of the barrier.

[0035] The monitoring unit 5 is used to monitor the pH value and conductivity of the barrier material during the stirring process of the stirring blade assembly.

[0036] The pH value and conductivity of the barrier material are monitored by the monitoring unit 5, so as to monitor in real time the uniformity of the barrier material and the formation soil 7 after in-situ mixing, and the progress of the carbonization reaction between carbon dioxide and the barrier material, so as to adjust the travel speed of the equipment and the amount of carbon dioxide aeration in real time, and improve the working performance of the construction equipment. The control unit 6 is used to control the working state of the storage unit 4. The amount and time of the slurry and gas delivered to the pipeline assembly by the storage unit 4 are controlled.

[0037] Preferably, Figure 2 , Figure 3 and Figure 4 As shown, the stirring tool assembly includes a stirring chain 301, a stirring blade 3011, a bracket 302, a chain guide wheel 303 and a power device 304. There are two chain guide wheels 303, which are installed at both ends of the bracket 302. The stirring chain 301 is sleeved on the two chain guide wheels 303. The power device 304 is connected to at least one chain guide wheel 303 to drive the chain guide wheel 303 to rotate. The bracket 302 is fixedly connected to the traction arm 2. The stirring blade 3011 is fixedly connected to the stirring chain 301.

[0038] When working, the power device 304 is turned on, and the power device 304 drives the chain guide wheel 303 to rotate, and the rotation of the chain guide wheel 303 drives the rotation of the stirring chain 301. In this way, the stirring blade 3011 fixedly connected to the stirring chain 301 also rotates accordingly. The stirring purpose is achieved through the action between the stirring blade 3011 and the formation soil 7.

[0039] Preferably, two chain guide wheels 303 are installed at the top and bottom of the bracket 302; the stirring blades 3011 are evenly distributed along the circumference of the stirring chain 301, and the distance between two adjacent stirring blades 3011 is 1 to 3 meters. Since the barrier is vertical, the stirring chain 301 is also arranged vertically. The two chain guide wheels 303 are installed at the top and bottom of the bracket 302 to realize the vertical arrangement of the stirring chain 301. The distance between two adjacent stirring blades 3011 is 1 to 3 meters. This distance can ensure that a stable-shaped mud vortex is formed around the stirring chain 301 during the operation of the stirring blades 3011, promoting the in-situ uniform mixing of the barrier filler and the formation soil 7. In addition, this distance can effectively suppress the splashing of the barrier material and reduce construction disturbances.

[0040] Preferably, Figure 1 As shown, the material storage unit 4 includes a filler storage tank 401, a compressed air storage tank 402 and a carbon dioxide storage tank 403. The pipeline assembly includes a first transmission pipeline 4013 and a second transmission pipeline 4032, and the first transmission pipeline 4013 and the second transmission pipeline 4032 are connected to the bracket 302. The filler storage tank 401 is connected to the first transmission pipeline 4013 through a first connecting pipe and a second connecting pipe connected to the first connecting pipe, and a first valve 4011 is provided in the first connecting pipe, and a second valve 4012 is provided in the second connecting pipe. The compressed air storage tank 402 is connected to the first transmission pipeline 4013 through a third connecting pipe and a second connecting pipe connected to the third connecting pipe, and a third valve 4021 is provided in the third connecting pipe; the first connecting pipe, the second connecting pipe and the third connecting pipe are connected through a three-way valve 4014. The carbon dioxide storage tank 403 is connected to the second transmission pipeline 4032 through a fourth connecting pipe, and a fourth valve 4031 is provided in the fourth connecting pipe.

[0041] The material storage unit 4 is used to provide filler, compressed air and carbon dioxide when building a barrier. The filler is a prior art, and a mixture obtained by activating bentonite with an alkaline silicate material can be used. The alkaline silicate material can be cement and / or slag. When building a barrier, the stirring blade 3011 rotates with the stirring chain 301. The filler in the filler storage tank 401 is transported to the barrier construction site through the first connecting pipe, the second connecting pipe and the first transmission pipeline 4013 in sequence. At this time, the filler and the soil are mixed by the stirring blade 3011. The first valve 4011 and the second valve 4012 are used to control the flow of the filler. The compressed air in the compressed air storage tank 402 is transported to the barrier construction site through the third connecting pipe, the second connecting pipe and the first transmission pipeline 4013 in sequence. The air, the filler and the soil are mixed by the stirring blade 3011. The third valve 4021 and the second valve 4012 are used to control the flow of compressed air. The carbon dioxide gas in the carbon dioxide storage tank 403 is transported to the construction barrier through the fourth connecting pipe and the second transmission pipeline 4032. The carbon dioxide gas, filler and soil are mixed by the stirring blade 3011. The fourth valve 4031 is used to control the flow of carbon dioxide.

[0042] Preferably, Figure 5 and Figure 6 As shown, the device also includes a distributed sensor 501, which is fixedly connected to the bracket 302. The distributed sensor 501 is arranged vertically along the bracket 302, and can collect data at different heights of the barrier. The distributed sensor 501 includes a pH value monitoring electrode and a conductivity monitoring electrode. The device also includes a data display terminal 502, which is used to display the pH value and conductivity information monitored by the distributed sensor 501. According to the pH value and conductivity information, the uniformity of the barrier material and the formation soil 7 after in-situ mixing, as well as the progress of the carbonization reaction of carbon dioxide with the barrier material are judged in real time. The monitoring unit 5 is connected to the distributed sensor 501 and the data display terminal 502 respectively.

[0043] Preferably, the control unit 6 is connected to the first valve 4011, the second valve 4012, the third valve 4021, and the fourth valve 4031, respectively. The control unit 6 controls the flow of the filler by controlling the opening and closing of the first valve 4011 and the second valve 4012. The control unit 6 controls the flow of compressed air by controlling the opening and closing of the third valve 4021 and the second valve 4012. The control unit 6 controls the flow of carbon dioxide by controlling the opening and closing of the fourth valve 4031. Through the control of the control unit 6, the barrier barrier constructed has good barrier properties and low permeability.

[0044] Preferably, Figure 5 and Figure 6As shown, the second transmission pipeline 4032 includes a second transmission main pipeline, a second transmission branch pipeline and a carbon dioxide injector 40321. The second transmission branch pipeline is horizontal, distributed vertically, and communicated with the second transmission main pipeline. The carbon dioxide injector 40321 is connected and communicated with the second transmission branch pipe, and a carbon dioxide injection switch 40322 is provided in the second transmission branch pipeline. The carbon dioxide injector 40321 and the carbon dioxide injection switch 40322 are respectively connected to the control unit 6.

[0045] The second transmission pipeline 4032 is used to transport carbon dioxide. A second transmission main pipeline and multiple second transmission branch pipelines are provided. The multiple second transmission branch pipelines are vertically distributed along the second transmission main pipeline. A carbon dioxide injector 40321 is connected to the end of each second transmission branch pipeline. Carbon dioxide is injected toward the constructed barrier material (soil, filler) through the carbon dioxide injector 40321. The injection surface of the carbon dioxide injector 40321 faces the constructed barrier material. A carbon dioxide injection switch 40322 is provided in the second transmission branch pipeline. The carbon dioxide injection switch 40322 controls the opening and closing of each second transmission branch pipeline. The control unit 6 controls the flow position of carbon dioxide by controlling the carbon dioxide injector 40321 and the carbon dioxide injection switch 40322.

[0046] Preferably, the overlapping length of adjacent carbon dioxide injectors 40321 is 0.1 to 0.3 times the length of the carbon dioxide injectors 40321. The overlapping of adjacent carbon dioxide injectors 40321 refers to the local surface of one carbon dioxide injector 40321 facing the local surface of another adjacent carbon dioxide injector 40321, forming an overlapping portion. Overlapping can increase the carbon dioxide aeration amount and carbonization degree of the barrier material between adjacent carbon dioxide injectors 40321. Clay minerals in the barrier material with a high carbonization degree form calcium carbonate crystal nuclei. Under the disturbance of the stirring blades, they diffuse in the non-overlapping parts of the carbon dioxide injector 40321, triggering carbonization precipitation reactions in areas with low carbon dioxide concentrations, thereby increasing the efficiency of carbon dioxide use. The length of the carbon dioxide injector 40321 is 1 to 5 m, and the number is the ratio of the length of the stirring tool assembly to the length of the carbon dioxide injector 40321. If the ratio is not an integer, it is rounded up. Fig.10 As shown, the injection surface of the carbon dioxide injector 40321 is provided with injection holes 403211 of different diameters. After the carbon dioxide passes through the injection holes 403211 of different diameters, carbon dioxide bubbles of different diameters are formed, which is conducive to the accumulation of bubbles in the high-viscosity barrier material. Compared with carbon dioxide bubbles of the same diameter, the contact area between the carbon dioxide bubbles of the same volume and the barrier material is larger, which promotes the progress of the carbonization precipitation reaction.

[0047] As an example, according to the design depth of the barrier, four carbon dioxide injectors 40321 are installed in the second transmission pipeline 4032. The length of the carbon dioxide injectors 40321 at both ends is 2.3 m, the length of the carbon dioxide injector 40321 in the middle is 2.6 m, and the overlap length of the two carbon dioxide injectors 40321 is 0.3 m. The pipe wall of the carbon dioxide injector 40321 is provided with injection holes 403211 with diameters of 0.1 mm, 0.3 mm, and 1.0 mm, respectively.

[0048] As a preferred example, Figure 7 , Figure 8 and Fig. 9 As shown, an anti-clogging nozzle is provided at the end of the first transmission pipeline 4013. The anti-clogging nozzle includes a nozzle tube 901, a nozzle 902, a separation piston 903 and a guide rail 904. The nozzle tube 901 is connected to the end of the first transmission pipeline 4013, the top of the guide rail 904 is fixedly connected to the inner wall of the nozzle tube 901, the bottom of the guide rail 904 is provided with a stopper, and the separation piston 903 is sleeved on the guide rail 904 and can move up and down along the guide rail 904. The nozzle 902 is located on the nozzle tube 901. When the separation piston 903 is located at the bottom of the guide rail 904, the nozzle 902 is located above the separation piston 903.

[0049] In the preferred embodiment, the first transmission pipeline 4013 is used to transport the filler and compressed air. When the equipment is in working state, the first transmission pipeline 4013 is located at the bottom of the barrier, and bears the pressure caused by the gravity of the barrier material. If the anti-clogging nozzle is not provided, after the filler injection is stopped, the barrier slurry will flow back into the first transmission pipeline 4013. Due to the forced carbonization of carbon dioxide, the barrier slurry will solidify and harden rapidly, and then a large amount of it will be deposited inside the first transmission pipeline 4013 to block it.

[0050] When the first transmission pipeline 4013 outputs the filler, the filler is ejected from the nozzle 902. At this time, under the action of the gravity and impact force of the filler, the separation piston 903 is located at the bottom of the guide rail 904. Figure 8 As shown, after the injection of the filler is stopped, the barrier slurry outside the nozzle 902 flows into the first transmission pipeline 4013 under the action of gravity, and driven by the mud, the separation piston 903 moves to the top of the guide rail 904, thereby closing the channel for the mud to flow back to the first transmission pipeline 4013, and the internal channel of the first transmission pipeline 4013 is isolated from the mud. In this process, a small amount of barrier slurry will accumulate and harden in the first transmission pipeline 4013, but due to the small amount of accumulation (height less than 10 cm), it cannot be completely blocked.

[0051] Preferably, the number of the nozzles 902 is 3 to 6 and they are distributed along the circumference of the nozzle tube 901. The nozzles 902 are located on the side wall of the nozzle tube 901 and do not affect the flow of the filler or compressed air. At the same time, the nozzles 902 are located on the side wall of the nozzle tube 901 and can cooperate with the separation piston 903. When the separation piston 903 moves upward to the top of the guide rail 904 or above the nozzle 902, the separation piston 903 achieves the purpose of blocking the end of the first transmission pipeline 4013.

[0052] In the embodiment, carbon dioxide is injected into the barrier to achieve forced carbonization of cement-based materials. On the one hand, the permeability coefficient of the barrier can be reduced to enhance the pollution control effect of the barrier; on the other hand, carbon fixation of the barrier in the contaminated site can be achieved, which has significant ecological and environmental benefits.

[0053] In the embodiment, the pH value and conductivity of the barrier are automatically monitored to determine the amount of carbon dioxide injection, thereby ensuring that the cement-based materials in the barrier achieve the best forced carbonization effect, thereby synergistically achieving carbon reduction and efficiency improvement in the field of pollution site management.

[0054] In the embodiment, the distributed real-time monitoring of the chemical parameters of the barrier slurry and the segmented carbon dioxide injector can fully adapt to the heterogeneity of the site strata. The injection amount of carbon dioxide is adjusted according to the physical and chemical properties of the stratum soil, and the refined control of the barrier construction is achieved through the monitoring and control linkage feedback.

[0055] The barrier is constructed in sections, with each section being 5 to 15 m. The design length of the barrier is 160 m, with each section being 10 m, so 16 sections need to be constructed. The embodiment constructs 10 sections, and the comparative example constructs the remaining 6 sections.

[0056] Example

[0057] After the base 1 moves to the place where the barrier needs to be built in the contaminated site, it stops moving. The process of building the barrier using the device of the present invention is as follows:

[0058] Step 1: Turn on the power device 304 , and the stirring chain 301 and the stirring blade 3011 of the stirring tool assembly rotate around the chain guide wheel 303 .

[0059] Step 2: The base 1 remains stationary, the traction arm 2 is opened, and the stirring tool assembly is driven to rotate around the traction arm axis 201 until the stirring tool assembly is in a vertical state. The rotation speed can be appropriately adjusted according to the soil quality of the stratum soil 7.

[0060] Step 3, operate the control switch 601 of the control unit 6, open the first valve 4011 and the second valve 4012 of the filler connected to the filler storage tank 401, so that the cement-based material in the filler storage tank 401 enters and passes through the first connecting pipe, the second connecting pipe and the first transmission pipe 4013 in sequence, and is sprayed out through the anti-clogging nozzle. Under the stirring action of the stirring blade 3011, the cement-based material is mixed with the formation soil 7 in situ.

[0061] Step 4: Turn on the monitoring unit 5 and display the pH value and conductivity value of the barrier material at different depths on the data display terminal 502 .

[0062] Step 5: operate the base 1 to move along the direction of the barrier; at the same time, keep the stirring tool assembly rotating at a constant speed until it reaches the end of the first barrier.

[0063] Step 6, operate the control switch 601 of the control unit 6, close the second valve 4012, open the third valve 4021, and press the filler in the pipeline between the three-way valve 4014 and the filler storage tank 401 into the filler storage tank 401; then close the first valve 4011, and then open the second valve 4012 to empty the filler between the three-way valve 4014 and the first transmission pipeline 4013 to prevent the filler from clogging the first transmission pipeline 4013.

[0064] The operating base 1 moves along the direction of the barrier, from the end of the first barrier to the beginning of the first barrier, while keeping the stirring tool assembly rotating at a constant speed. After reaching the beginning of the first barrier, the second valve 4012 and the third valve 4021 are closed.

[0065] Step 6 can increase the uniformity of the filler and the formation soil 7 by means of enhanced disturbance of compressed air. On the data display terminal 502, it can be observed that the pH value and the conductivity value of the barrier material at different depths tend to be consistent.

[0066] In step 6, after adding air to the cement-based material, tiny bubbles are formed in the barrier slurry. The "ball effect" of the bubbles can reduce the viscosity of the barrier slurry, making it easier to stir, thereby improving construction efficiency. In addition, under the action of oxygen in the air, the redox potential of the barrier slurry increases, changing the surface charge state of the clay mineral surface, thereby promoting its adsorption of calcium ions. Under the action of calcium ions, the double electrical layer of the clay minerals in the barrier slurry is compressed, and the fluidity is significantly improved, thereby promoting the in-situ mixing of the filler and the formation soil.

[0067] Step 7: Keep the base 1 still, open the traction arm 2, and drive the stirring tool assembly to rotate around the traction arm axis 201 until the angle between the stirring tool assembly and the vertical direction is 15°. By properly tilting the stirring tool assembly, the forced carbonization effect of the barrier can be increased.

[0068] Step 8, operate the base 1 to move along the barrier; operate the control switch 601 of the control unit 6, open the fourth valve 4031 and the carbon dioxide injection switch 40322, and inject carbon dioxide; at the same time, keep the stirring tool assembly rotating at a constant speed until it reaches the end of the first barrier.

[0069] In step 8, the progress of the forced carbonization reaction is determined by the pH value and conductivity value of the barrier material. The condition for the completion of forced carbonization is that the pH value and conductivity value no longer show a significant decrease. For example, the time interval between two test monitorings is 30s, and the data shows that the difference between the two readings of pH value and conductivity on terminal 502 is less than 10% of the previous monitoring value, which is considered to be a non-significant decrease. According to the pH value and conductivity value of the barrier material, the moving speed of the base 1 is appropriately adjusted to ensure that the forced carbonization reaction is completed during the movement of the base 1.

[0070] Through forced carbonization, the barrier material accelerates the dissolution of alkaline compounds in cement-based materials, promotes the hydration reaction of silicates, and quickly generates hydrated calcium silicate; at the same time, the generated calcium carbonate product can fill the pores inside the material, effectively reducing the porosity and permeability of the material, thereby improving the service performance and durability of the barrier material in a short time (8 hours). Compared with the 28-day curing age under non-forced carbonization conditions, the construction period of the barrier is significantly reduced, and the normal service time is significantly advanced.

[0071] Step 9, after the first barrier is constructed, the control switch 601 of the control unit 6 is operated to close the fourth valve 4031 and the carbon dioxide injection switch 40322; the traction arm 2 is opened to drive the stirring tool assembly to rotate around the traction arm axis 201 until the stirring tool assembly is in a vertical state.

[0072] Repeat steps 1 to 9 to complete the construction of 10 barrier barriers.

[0073] Comparative Example

[0074] The comparative example is the same as the example, except that when constructing each barrier barrier, step 8, that is, the step of injecting carbon dioxide for forced carbonization, is omitted. The remaining 6 barrier barriers are constructed in the comparative example.

[0075] Usually, the overlap of the barrier construction is a weak point of the structure, so samples are taken at the overlap between two barrier barriers. Samples are taken at the overlap between the 5th and 6th barrier barriers constructed in the embodiment, and at the overlap between the 4th and 5th barrier barriers constructed in the comparative example. Each point is sampled from shallow to deep in depth, at depths of 3.0 m, 6.0 m and 8.0 m respectively.

[0076] The permeability coefficient of the barrier sample was tested and the results were as follows: Fig.12 As shown. Fig.12 It can be seen that the permeability coefficient of the barrier sample in the embodiment is significantly lower than that in the comparative example. The average permeability coefficients of the samples at different depths in the embodiment and the comparative example are 1.87×10 -9 cm / s and 1.44×10 -8 cm / s.

[0077] It can be seen from the test results of the embodiments and comparative examples that after forced carbonization treatment, the permeability coefficient of the barrier is reduced by about 1 order of magnitude, and the barrier performance is significantly improved.

[0078] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments, and the descriptions in the above specific embodiments and the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed for protection.

Claims

1. A device for constructing a barrier to contaminated sites, characterized in that: It comprises a walking base (1), a traction arm (2), a stirring knife assembly, a material storage unit (4), a monitoring unit (5) and a control unit (6); wherein: The stirring tool assembly is connected to the base (1) via a traction arm (2), and the traction arm (2) can drive the stirring tool assembly to rotate around the axis (201) of the traction arm; The material storage unit (4) is connected to a pipeline assembly; one end of the pipeline assembly is fixed on the stirring tool assembly; The monitoring unit (5) is used to monitor the pH value and conductivity of the barrier material during the stirring process of the stirring knife assembly; The control unit (6) is used to control the working state of the material storage unit (4); The stirring tool assembly comprises a stirring chain (301), a stirring blade (3011), a bracket (302), a chain guide wheel (303) and a power device (304); the chain guide wheels (303) are two and are mounted on both ends of the bracket (302); the stirring chain (301) is sleeved on the two chain guide wheels (303); the power device (304) is connected to at least one chain guide wheel (303) to drive the chain guide wheel (303) to rotate; the bracket (302) and the traction arm (2) are fixedly connected; the stirring blade (3011) is fixedly connected to the stirring chain (301); The material storage unit (4) comprises a filler storage tank (401), a compressed air storage tank (402) and a carbon dioxide storage tank (403); the pipeline assembly comprises a first transmission pipeline (4013) and a second transmission pipeline (4032), wherein the first transmission pipeline (4013) and the second transmission pipeline (4032) are connected to the bracket (302); the filler storage tank (401) is connected to the first transmission pipeline (4013) via a first connecting pipe and a second connecting pipe connected to the first connecting pipe, wherein a first valve ( 4011), a second valve (4012) is provided in the second connecting pipe; the compressed air storage tank (402) is connected to the first transmission pipeline (4013) through a third connecting pipe and a second connecting pipe connected to the third connecting pipe, and a third valve (4021) is provided in the third connecting pipe; the first connecting pipe, the second connecting pipe and the third connecting pipe are connected through a three-way valve (4014); the carbon dioxide storage tank (403) is connected to the second transmission pipeline (4032) through a fourth connecting pipe, and a fourth valve (4031) is provided in the fourth connecting pipe; It also includes a distributed sensor (501), wherein the distributed sensor (501) is fixedly connected to the bracket (302); it also includes a data display terminal (502), wherein the data display terminal (502) is used to display pH value and conductivity information monitored by the distributed sensor (501); the monitoring unit (5) is connected to the distributed sensor (501) and the data display terminal (502), respectively; The second transmission pipeline (4032) comprises a second transmission main pipeline, a second transmission branch pipeline and a carbon dioxide injector (40321); the second transmission branch pipeline is horizontal, distributed vertically, and communicated with the second transmission main pipeline; the carbon dioxide injector (40321) is connected to and communicated with the second transmission branch pipeline, and a carbon dioxide injection switch (40322) is provided in the second transmission branch pipeline; the carbon dioxide injector (40321) and the carbon dioxide injection switch (40322) are respectively connected to a control unit (6).

2. The device according to claim 1, characterized in that The two chain guide wheels (303) are mounted at the top and bottom of the bracket (302); the stirring blades (3011) are evenly distributed along the circumference of the stirring chain (301), and the distance between two adjacent stirring blades (3011) is 1 to 3 m.

3. The device according to claim 1, characterized in that The control unit (6) is respectively connected to the first valve (4011), the second valve (4012), the third valve (4021), and the fourth valve (4031).

4. The device according to claim 1, characterized in that The overlapping length of adjacent carbon dioxide injectors (40321) is 0.1 to 0.3 times the length of the carbon dioxide injector (40321); the length of the carbon dioxide injector (40321) is 1 to 5 m; and the injection surface of the carbon dioxide injector (40321) is provided with injection holes (403211) of different diameters.

5. The device according to claim 1, characterized in that An anti-clogging nozzle is provided at the end of the first transmission pipeline (4013), and the anti-clogging nozzle comprises a nozzle tube (901), a nozzle (902), a separation piston (903) and a guide rail (904); wherein: The nozzle tube (901) is connected to the end of the first transmission pipeline (4013); the top end of the guide rail (904) is fixedly connected to the inner wall of the nozzle tube (901); a limiter is provided at the bottom end of the guide rail (904); the separation piston (903) is sleeved on the guide rail (904) and can move up and down along the guide rail (904); the nozzle (902) is located on the nozzle tube (901); when the separation piston (903) is located at the bottom end of the guide rail (904), the nozzle (902) is located above the separation piston (903).

6. The device according to claim 5, characterized in that The number of the nozzles (902) is 3 to 6 and they are distributed along the circumference of the nozzle tube (901).

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