A 3D printing method for emergency isolation barriers at contaminated sites

Abstract

The present invention belongs to the field of printing of structures in contaminated sites, and discloses a 3D printing method for emergency barrier barriers in contaminated sites, which meets the needs of 3D printing barrier barriers in contaminated sites and improves the barrier barrier performance of pollutants. The method includes: step 10, collecting contaminated site information; the contaminated site information includes the distribution range of site pollution; the types of pollutants and chemical and physical properties; step 20, determining the construction parameters of the barrier barrier according to the collected contaminated site information; the construction parameters include printing boundaries, printing thickness D, printing direction and printing order; step 30, printing the barrier barrier above the contaminated site according to the determined construction parameters of the barrier barrier; the barrier barrier has a layered structure and is composed of at least 2 layers, and each layer of the barrier barrier is composed of at least 2 printing strips; a reinforcing line is provided on the side of each printing strip, and a reinforcing net is provided at the bottom of each printing strip.

Description

Technical Field

[0001] The present invention belongs to the field of printing of structures in contaminated sites, and in particular, relates to a 3D printing method for emergency isolation barriers in contaminated sites. Background Art

[0002] The emergency response to sudden environmental pollution incidents is an international problem. Sudden environmental pollution incidents are characterized by uncertainty and concentrated discharge of pollutants in a short period of time. If not controlled in time, they will have a bad impact on environmental media such as surface soil, groundwater, and atmosphere, as well as surrounding humans, vegetation, and organisms. Cutting off and controlling the pollution source and preventing the spread of pollution are effective methods for dealing with sudden soil pollution.

[0003] Barriers can effectively control the migration of pollutants or block the exposure pathways of pollutants, and are the most commonly used and effective technology for risk control of contaminated sites. Traditional compacted clay requires heavy equipment for compaction; after the soil-geomembrane composite horizontal barrier is laid, the traffic capacity of emergency disposal machinery and equipment is poor. Therefore, the existing technology is difficult to meet the emergency disposal needs of sudden environmental pollution incidents. The construction of fast-forming, high-toughness barrier materials through 3D printing technology can effectively overcome the disadvantages of traditional barrier materials. However, compared with the 3D printing technology in the traditional construction field, the barrier of contaminated sites not only pays attention to the strength of the wall, but also pays more attention to the performance of the printed structure in blocking pollutants. Compared with the vertical wall of 3D printing, the horizontal barrier is thinner, but the number of printed strips in the horizontal direction is large, so there are a large number of splicing cold seams. The bonding strength of the cold seams between these printed strips is low, which has a great impact on the performance of blocking pollutants. At the same time, during the solidification of the material, due to the dehydration and cracking, the pores, cracks and other advantageous channels are generated, which significantly reduces its ability to block the migration of pollutants. Therefore, this field urgently needs to develop efficient construction methods that meet the 3D printing process of contaminated sites. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the existing technology, a 3D printing method for emergency isolation barriers in contaminated sites is provided to meet the needs of 3D printing isolation barriers in contaminated sites and improve the performance of the isolation barriers in isolating pollutants.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A 3D printing method for an emergency barrier for a contaminated site comprises the following steps:

[0007] Step 10, collecting contaminated site information; the contaminated site information includes the distribution range of site pollution; types of pollutants and chemical and physical properties;

[0008] Step 20, determining the construction parameters of the barrier according to the contaminated site information collected in step 10; the construction parameters include printing boundary, printing thickness D, printing direction and printing order;

[0009] Step 30, according to the construction parameters of the barrier determined in step 20, printing a barrier above the contaminated site; the barrier has a layered structure and is composed of at least two layers, and each layer of the barrier is composed of at least two printing strips; a reinforcement line is provided on the side of each printing strip, and a reinforcement net is provided at the bottom of each printing strip.

[0010] As a preferred example, in step 20, the printing boundary is the boundary of the site pollution distribution range extending outward by 3 to 10 meters.

[0011] As a preferred example, in step 20, the printing thickness D is measured according to formula (1):

[0012] D=0.10+n1×f1+n2×f2+(M20)×n3×f3 Formula (1)

[0013] In the formula, D represents the printing thickness of the barrier, unit: m; n1 represents the adjustment coefficient of emergency personnel entering the site, unit: m / time, and the value is 0.001~0.005; f1 represents the number of emergency personnel entering the site, unit: times; n2 represents the adjustment coefficient of emergency equipment entering the site with a mass less than 20 tons, unit: m / time, and the value is 0.005~0.015; f2 represents the number of emergency equipment entering the site with a mass less than 20t, unit: times; M represents the mass of emergency equipment with a mass greater than or equal to 20t, unit: t; n3 represents the adjustment coefficient of emergency equipment entering the site greater than or equal to 20t, unit: m / (t×time), and the value is 0.01~0.05; f3 represents the number of emergency equipment entering the site greater than or equal to 20t, unit: times.

[0014] As a preferred example, in step 20, the printing order is as follows:

[0015] Step 201: Divide the printing area enclosed by the printing boundary into units of frames, each of which is a square, and the side length L is calculated according to formula (2):

[0016]

[0017] Where, T represents the allowed printing time, unit: s; v1 represents the moving speed of the print head of the printing machine, unit: m / s; v2 represents the no-load moving speed of the print head of the printing machine, unit: m / s; w represents the width of the printing tape, unit: m;

[0018] Step 202, printing a barrier layer by layer from bottom to top, printing at least 2 print strips on each layer, and then printing the previous layer until the barrier is printed;

[0019] Step 203: Print the next barrier according to the method of step 202 until the printing is completed.

[0020] As a preferred example, in step 202, when printing the previous layer, the time for the printing device to transfer from the printing end point of the next layer of barrier to the printing start point of the previous layer of barrier is called the allowed printing time T, which is m times the printable time t of the barrier material; if the barrier is printed by a swing-arm printing device, the value of m is 0.80 to 0.90; if the barrier is printed by a frame printing device, the value of m is 0.85 to 0.98.

[0021] As a preferred example, in step 30, in two vertically adjacent layers of barrier barriers, the center line of each printing strip is opposite to the boundary of the vertically adjacent printing strips; and the width of the printing strip is 10 to 30 cm.

[0022] As a preferred example, in step 30, the reinforcement line is located at 1 / 2 of the height of the side of each printing belt, and an anti-slip line is provided on the reinforcement line.

[0023] As a preferred example, the anti-slip line is perpendicular to the axis of the reinforcement line, and the length of the anti-slip line is 3 to 6 times the maximum particle size of the aggregate in the printing material; there are N anti-slip lines, which are arranged in groups, and each group of anti-slip lines includes 3 to 8 anti-slip lines, and the anti-slip lines are evenly distributed along the axial direction of the reinforcement line; the spacing between adjacent anti-slip lines is 1 to 3 times the length of the anti-slip line; in each group of anti-slip lines, the anti-slip lines are evenly distributed circumferentially along the reinforcement line, the angles between adjacent anti-slip lines are equal, and the anti-slip lines and reinforcement lines are three-dimensional.

[0024] As a preferred example, in step 30, the reinforcing mesh is woven from reinforcing wires provided with anti-slip wires.

[0025] As a preferred example, the grid of the reinforcing net is a square, and the side length of the grid is 0.2 to 0.6 times the width of the printing tape.

[0026] Compared with the prior art, the 3D printing method for emergency barrier barriers for contaminated sites in the embodiment of the present invention meets the needs of 3D printing barrier barriers at contaminated sites and improves the barrier barrier performance in blocking pollutants. The printing method includes step 10, collecting contaminated site information; step 20, determining the construction parameters of the barrier barriers based on the collected contaminated site information; step 30, printing the barrier barriers above the contaminated site based on the determined construction parameters of the barrier barriers; the barrier barriers are layered and consist of at least 2 layers, and each layer of the barrier barriers consists of at least 2 printing strips; a reinforcement line is provided on the side of each printing strip, and a reinforcement net is provided on the bottom of each printing strip. The barrier barriers printed by this printing method provide earlier disposal conditions for emergency disposal of site pollution and effectively prevent the spread of pollutants to a wider range. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A top view of a printed barrier according to an embodiment of the present invention positioned above a contaminated site;

[0028] Figure 2 A side view of a containment barrier printed for an embodiment of the present invention positioned above a contaminated site;

[0029] Figure 3 is a schematic structural diagram of a reinforcement line in an embodiment of the present invention;

[0030] Figure 4 is a side view of a reinforcement line in an embodiment of the present invention;

[0031] Figure 5 A top view of a sampling position in an embodiment of the present invention;

[0032] Figure 6 for Figure 5 A-A' section view;

[0033] Figure 7 It is a side view of the inner convex field barrier in the printing direction in the embodiment of the present invention;

[0034] Figure 8 A side view of the concave field barrier in the printing direction in an embodiment of the present invention;

[0035] Fig. 9 This is a side view of the flat field barrier in the printing direction in an embodiment of the present invention.

[0036] The figure includes: contaminated site 1, barrier 2, printing tape 201, reinforcement line 3, anti-slip line 4, reinforcement net 5, and sampling hole 6. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is described in detail below. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0038] like Figure 1 and Figure 2 As shown, a 3D printing method for an emergency barrier for a contaminated site according to an embodiment of the present invention comprises the following steps:

[0039] Step 10: Collect information about the contaminated site. The contaminated site information includes the distribution range of the site pollution; the types of pollutants and their chemical and physical properties. The distribution range of the site pollution is initially determined by the smell and color of the soil and groundwater, and then the distribution range of the site pollution is accurately portrayed by sampling and testing the soil, groundwater and soil gas.

[0040] Step 20, based on the contaminated site information collected in step 10, determine the construction parameters of the barrier 2. The construction parameters include printing boundary, printing thickness D, printing direction and printing order. The printing area is divided into units of sheets. The printing direction refers to the construction order of different sheets of barrier, from one end to the other, or from both ends to the middle, or from the middle to both ends. For an inner convex site, if Figure 7 As shown, the barrier is printed in the order of a, b, c, d, and e, starting from the low-lying boundary of the site and ending at the top of the raised site. For a concave site, Figure 8 As shown in the figure, the barrier is printed in the order of a, b, c, d, and e, starting from the low-lying part of the site and ending at the raised edge of the site. For a flat site, Fig. 9 As shown, the isolation barriers are printed in the order of a, b, c, d, and e, starting from the location where the pollutants are most shallowly distributed and ending at the periphery of the site.

[0041] Step 30, according to the construction parameters of the barrier determined in step 20, printing the barrier 2 above the contaminated site 1; the barrier 2 is a layered structure, and is composed of at least 2 layers, and each layer of the barrier 2 is composed of at least 2 printing tapes 201; a reinforcement line 3 is provided on the side of each printing tape 201, and a reinforcement net 5 is provided on the bottom of each printing tape 201.

[0042] The 3D printing method of the above embodiment prints a horizontal composite barrier, which covers the contaminated site 1 to achieve the barrier of volatile pollutants in the contaminated site 1. The barrier 2 is a layered structure and is composed of at least two layers. Each layer of the barrier 2 is composed of at least two printing strips 201; a reinforcement line 3 is provided on the side of each printing strip 201, and a reinforcement net 5 is provided at the bottom of each printing strip 201. Each reinforcement line 3 is partially embedded in the side of a printing strip 201, and the other part of the reinforcement line 3 is embedded in the side of another printing strip 201 adjacent to the printing strip 201. In this way, two adjacent printing strips 201 in the same layer are connected together by a reinforcement line 3. After the reinforcement line 3 is set between two adjacent printing tapes, on the one hand, the adsorption effect of the reinforcement line 3 and the printing material can promote the deposition of the printing paste between the interface of the newly printed printing tape and the interface of the old printing tape that has been printed, and reduce the void area formed by the air wrapped between the interface of the new and old printing tapes (two adjacent printing tapes), thereby effectively increasing the bonding strength between the interface of the new and old printing tapes and reducing the formation of dominant channels. In addition, under the synergistic effect of the reinforcement line 3 and the anti-skid line 4, the printing paste at the contact interface of the two adjacent printing tapes forms a composite structure through the physical adsorption, chemical bonding and mechanical interlocking between the interface of the reinforcement line 3 and the printing paste, and the effect of the anti-skid line 4 and the paste significantly improves the density of the transition zone between the interfaces of the two adjacent printing tapes, thereby reducing the void development and crack formation during the hardening and dehydration process of the material.

[0043] A reinforcing net 5 is provided at the bottom of the printing tape 201. Part of the reinforcing net 5 is embedded in the bottom surface of a printing tape 201, and the other part of the reinforcing net 5 is embedded in the top surface of the printing tape 201 below the printing tape 201. In this way, the two printing tapes 201 in the upper and lower adjacent layers are connected together by the reinforcing net 5. The reinforcing net 5 provided between the two layers of printing tapes not only has the same effect as the reinforcing wire 3 in improving the cohesion of the interface between the adjacent printing tapes, reducing the debonding area, and increasing the strength and barrier performance of the barrier, but also can effectively improve the flow state of the material after printing. In particular, for the case where the ground of the site is undulating (the slope is greater than 30°), the change in slope causes a significant change in the thickness of each layer of the printing barrier at different positions, thereby reducing the barrier performance of the barrier as a whole and increasing the weak points for organic matter to penetrate. By directly providing the reinforcing net 5 between the two adjacent printing tapes, the lateral flow of the printing material under the action of gravity after printing is effectively suppressed, so that the thickness of the printing barrier is more uniform.

[0044] The barrier barrier 2 printed by the printing method of the above embodiment can realize the barrier function after printing, does not require maintenance, and is suitable for emergency situations.

[0045] To enhance the barrier effect, Figure 1As shown, in step 20, the printing boundary is the boundary of the site pollution distribution range extending outward by 3 to 10 meters. Figure 1 In the figure, the gray part in the middle is the contaminated site 1, and the dotted box is the printing boundary.

[0046] Preferably, in step 20, the printing thickness D is measured according to formula (1):

[0047] D=0.10+n1×f1+n2×f2+(M-30)×n3×f3 Formula (1)

[0048] In the formula, D represents the printing thickness of the barrier, unit: m; n1 represents the adjustment coefficient of emergency personnel entering the site, unit: m / time, with a value of 0.001~0.005; f1 represents the number of emergency personnel entering the site, unit: times; n2 represents the adjustment coefficient of emergency equipment entering the site with a mass less than 20t, unit: m / time, with a value of 0.005~0.015; f2 represents the number of emergency equipment entering the site with a mass less than 20t, unit: times; M represents the mass of emergency equipment with a mass greater than or equal to 20t, unit: t; n3 represents the adjustment coefficient of emergency equipment entering the site greater than or equal to 20t, unit: m / (t×time), with a value of 0.01~0.05; f3 represents the number of emergency equipment entering the site greater than or equal to 20t, unit: times.

[0049] According to the values ​​measured by formula (1), the printing thickness is determined. The printing time and printing material consumption of the barrier are the key points of emergency disposal of contaminated sites. Unlike traditional contaminated site remediation and management, emergency disposal of sudden environmental pollution is uncertain. During emergency disposal, a large number of inspection personnel are required to enter the site for multiple inspections and tests, and heavy emergency disposal equipment will place higher requirements on the mechanical strength of the barrier. Through formula (1), the number of emergency personnel entering the site, the quality of emergency equipment and the number of entering the site are fully considered, and the thickness of the barrier is accurately calculated, which can not only optimize the amount of materials, but also effectively reduce the construction period, which is of great significance to the emergency disposal of sudden environmental accidents.

[0050] Preferably, in step 20, the printing order is as follows:

[0051] Step 201: Divide the printing area enclosed by the printing boundary into units of frames, each of which is a square, and the side length L is calculated according to formula (2):

[0052]

[0053] Wherein, T represents the allowed printing time, unit: s; v1 represents the moving speed of the print head of the printing machine, unit: m / s; v2 represents the no-load moving speed of the print head of the printing machine, unit: m / s; w represents the width of the printing tape 201, unit: m.

[0054] Step 202 , for a piece of barrier barrier 2 , printing is performed layer by layer from bottom to top, with at least two printing strips 201 printed on each layer, and then printing is performed on the previous layer until the barrier barrier 2 is printed.

[0055] In step 202, when printing the previous layer, the time for the printing device to transfer from the printing end point of the next layer of barrier barrier 2 to the printing start point of the previous layer of barrier barrier 2 is called the allowed printing time T, which is defined as m times the printable time t of the barrier barrier material. Completing the printing of two layers of barrier barriers 2 within the printable time t can ensure that the printing material in the previous printing layer is in a good flow state, promote the bonding effect between the reinforcing net 5 and the anti-slip line 4 between the upper and lower layers of printing tapes, and inhibit the formation of defects between the printed cold seams, thereby effectively ensuring the construction quality of the barrier barrier, and minimizing the construction period, meeting the requirements of emergency disposal of environmental pollution. If the barrier barrier 2 is printed by a swing arm printing device, the value of m is 0.80-0.90; if the barrier barrier 2 is printed by a frame printing device, the value of m is 0.85-0.98.

[0056] Step 203: Print the next barrier 2 according to the method of step 202 until the printing is completed.

[0057] In the process of determining the above printing order, the printing area is divided by width, and the barrier 2 is printed in units of width. After one barrier barrier 2 is printed, another barrier barrier 2 is printed. The construction of the barrier barrier in sections can achieve refined control of the construction quality of the barrier barrier. Through section-by-section construction, the area of ​​each section is effectively associated with the printable time of the material. Under the premise of ensuring the construction and workability of the printed material, the construction cycle is optimized to the greatest extent, providing support for the automated and intelligent design of barrier barrier printing. In addition, in order to control the printing quality and adjust the construction process, sampling tests and process parameter calculations are carried out in units of width, which is more objective.

[0058] Preferably, in step 30, in two vertically adjacent layers of barrier barriers 2, the center line of each printing tape 201 is opposite to the boundary of the vertically adjacent printing tape 201. The width of the printing tape 201 is 10 to 30 cm. By staggering the upper and lower layers of printing tapes, the influence of the printing cold seam between the printing tapes on the service performance of the barrier barrier can be fully avoided. Reasonable setting of the width of the printing tape can improve the efficiency of the printing construction of the barrier barrier. If the printing tape is too wide, the printing interface will be non-homogeneous, and the cross-section of the printed strips will vary greatly; if the printing tape is too narrow, there will be too many printing cold seams, which will promote the development of dominant channels. The width of the printing tape is controlled within the range of 10 to 30 cm, which can optimize the printing quality and printing efficiency of the barrier barrier.

[0059] Preferably, in step 30, the reinforcing line 3 is located at 1 / 2 of the height of the side of each printing tape 201, and an anti-slip line 4 is provided on the reinforcing line 3. By providing the reinforcing line 3 at 1 / 2 of the height of the side of the printing tape 201, it is possible to ensure that the bonding strength of two adjacent printing tapes 201 is improved, and avoid obvious stress concentration in the vertical section where the bonding interface is located under the action of external load, which leads to secondary cracking of the printed cold seam between two adjacent printing tapes. In addition, after the reinforcing line 3 is provided at 1 / 2 of the height of the side of the printing tape 201, the printing tape maintains its initial shape after being ejected, avoiding obvious thickness differences when the slope changes greatly.

[0060] Preferably, Figure 3 and Figure 4 As shown, the anti-skid line 4 is perpendicular to the axis of the reinforcing line 3, and the length of the anti-skid line 4 is 3 to 6 times the maximum particle size of the aggregate in the printed material. Usually, the printed material is composed of aggregate and gel material. By reasonably setting the length of the anti-skid line 4 on the reinforcing line 3, the mechanical interlocking effect between the anti-skid line 4 and the aggregate in the barrier can be adjusted to increase the mechanical properties of the composite structure. The stress borne on the reinforcing line 3 is transferred to the hardened slurry through the anti-skid line 4, reducing the number and size of cracks and internal microcracks in the barrier, and improving the continuity of the barrier. During the force process, the anti-skid line 4 and the reinforcing line 3 change the stress field of the hardened slurry, and the bridging effect of the anti-skid line 4 is used to prevent or delay the expansion of the cracks, thereby improving the toughness of the barrier under external loads during emergency disposal. If the length of the anti-skid line 4 is too large, agglomerates will be formed and cavities will be generated in the barrier; if the length of the anti-skid line 4 is too small, effective friction cannot be formed, and the mechanical interlocking effect is not obvious.

[0061] There are N anti-skid lines 4 arranged in groups, each group of anti-skid lines includes 3 to 8 anti-skid lines 4, and the anti-skid lines 4 are evenly distributed along the axial direction of the reinforcement line 3. Arranging the anti-skid lines in groups facilitates processing and production, and reduces the economic cost of the barrier.

[0062] The spacing between adjacent anti-skid lines is 1 to 3 times the length of the anti-skid line 4. In each group of anti-skid lines, the anti-skid lines 4 are evenly distributed along the circumference of the reinforcement line 3, the angles between adjacent anti-skid lines are equal, and the anti-skid lines 4 and the reinforcement line 3 are combined to form a three-dimensional shape. That is, all anti-skid lines 4 on the same reinforcement line 3 are not on the same plane. The anti-skid lines 4 and the reinforcement line 3 are combined to form a three-dimensional shape, which can ensure the uniform distribution of the anti-skid lines 4 in two adjacent printing strips, and effectively avoid the anti-skid lines 4 just adhering to the middle of the two adjacent printing strips without being embedded in the printing material of the printing strip.

[0063] In the above embodiment, the reinforcing line 3 and the anti-skid line 4 work together. The anti-skid line 4 can improve the bonding strength and interface area between the reinforcing line 3 and the printing slurry. Under the synergistic effect of the reinforcing line 3 and the anti-skid line 4, the printing slurry at the contact interface of two adjacent printing tapes forms a composite structure through the physical adsorption, chemical bonding and mechanical interlocking between the interface between the reinforcing line 3 and the anti-skid line 4 and the printing slurry, thereby increasing the internal stress caused by water loss and cracking of the barrier during maintenance, the mechanical strength under external loads during service, and the pollution barrier performance.

[0064] Preferably, in step 30, the reinforcing mesh 5 is woven from reinforcing wires 3 provided with anti-skid wires 4. Since the anti-skid wires 4 and reinforcing wires 3 are combined to form a three-dimensional shape, the reinforcing mesh 5 woven from the anti-skid wires 4 and reinforcing wires 3 is also three-dimensional. This can ensure that the anti-skid wires 4 on the reinforcing mesh 5 are evenly distributed in the printing slurry of two adjacent printing layers, effectively avoiding that the anti-skid wires 4 are only adhered between the two adjacent printing layers, but not embedded in the printing material, so that the reinforcing mesh 5 reflects the optimal reinforcement effect on the service performance of the barrier.

[0065] Preferably, the grid of the reinforcing net 5 is a square, and the side length of the grid is 0.2 to 0.6 times the width of the printing tape 201. The friction between the reinforcing net 5 and the surface of the printing tape 201 can constrain the lateral displacement of the printing slurry and improve the self-supporting stability of the soil. By locking the aggregate of the printing slurry, its movement is restricted, and the lateral deformation and uneven settlement of the printing slurry are prevented. In addition, the reinforcing net 5 can bear the load together with the barrier, improve the bearing capacity and stability of the barrier, and disperse the concentrated stress to a wider area, reducing local stress concentration, thereby reducing deformation and damage to the soil. This reinforcement effect is particularly important for the bearing capacity during emergency disposal of contaminated sites.

[0066] In the above embodiment, reinforcing wires 3 and reinforcing meshes 5 are arranged between the printing strips. These reinforcing fibers can effectively improve the bonding performance between the printing strips and enhance the service performance of the barrier.

[0067] Compare the samples in the area near the cold seam of the 3D printed barrier and the barrier effects before and after setting the reinforcement wire and reinforcement net.

[0068] Sample 1 is 2 layers thick, with a reinforcement net set between the two layers. Each layer is equipped with 2 printing tapes, and reinforcement lines are set between the printing tapes. The width of the printing tape is 30cm, the length is 10m, and the thickness is 10cm. Every 10 meters of reinforcement line 2 is equipped with 125 sets of anti-slip lines, each set of anti-slip lines includes 4 anti-slip lines, and the length of each anti-slip line is 1cm (5 times the maximum particle size of 2mm of the aggregate in the printing material). The grid side length of the reinforcement net is 9cm (0.3 times the width of the printing tape). Figure 5 and Figure 6As shown, a sampling hole 6 is set between two adjacent printing strips in the same layer, and the sampling hole 6 penetrates the upper and lower layers for sampling. The first sample obtained by sampling is a cylindrical sample with a diameter of 20 cm and a height of 20 cm.

[0069] Sample 2 is the same as Sample 1, but no reinforcing mesh is provided between the two layers, and no reinforcing wire is provided between the printing strips. Sampling is performed at the same sampling position as Sample 1 to obtain a second sample of the same size.

[0070] The permeability coefficient of the cold joint area of ​​the barrier of the above two samples was tested with reference to the "Test Code for Cement and Cement Concrete for Highway Engineering" (JTG 3420-2020). The test results are: the permeability coefficient of the first sample is 2.71×10 - 7 cm / s, and the permeability coefficient of the second sample is 6.05×10 -6 cm / s. Therefore, after setting the reinforcement wire and reinforcement net, the pollution barrier performance of the cold seam area of ​​the 3D printed barrier is significantly improved, and the permeability coefficient is reduced by more than one order of magnitude.

[0071] The present invention effectively controls the migration of pollutants or blocks the exposure pathway of pollutants through the toughening effect of the reinforcing wires made of fibers arranged between the printing strips and the toughening effect of the reinforcing nets made of fibers arranged between the printing layers, thereby achieving efficient emergency disposal of sudden soil environmental pollution incidents.

[0072] Two embodiments and one comparative example are given below to demonstrate that the method of the present invention can save materials.

[0073] The barrier printing area is 120m 2 , of which the travel path area of ​​30t emergency equipment is 25m 2 ; The travel path area for emergency equipment weighing less than 20 tons is 30m 2 ; Other areas are for emergency personnel to enter, with an area of ​​65m 2 . Set n1 to 0.005m / time, f1 to 10 times; set n2 to 0.01m / time, f2 to 5 times;

[0074] The value of n3 is 0.02m / time, and f3 is 2 times.

[0075] Comparative example: Traditional barrier materials are usually filled in the entire contaminated site, with a thickness of 0.5 to 1.0 m. Based on the average value (0.75 m), the required barrier material is 0.75*120=90 m. 3 .

[0076] Example 1: According to the method of the present invention, the printing design is completed in two steps

[0077] Usually, the thickness of the barrier in the printing area is equal. In the first stage, emergency personnel and emergency equipment weighing less than 20 tons are considered to enter the site. If a major pollution source is found during the emergency process and emergency equipment weighing more than 20 tons is required to enter the site, the second stage of barrier printing construction will be carried out again. According to this calculation, the volume of materials required for printing in the first stage is 120×(0.10+0.005×10+0.01×5)=24m 3 The volume of printed materials required in the second stage is 25×(0.10+0.005×10+0.01×5+0.02×2×10)=15m 3 ; The total volume of printing materials required for the two stages is 39m 3 .

[0078] Embodiment 2: According to the method of the present invention, the printing design is completed in one step

[0079] The travel path area of ​​30t emergency equipment is 25m 2 The volume of printing material required is 25×(0.10+0.005×10+0.01×5+0.02×2×10)=15m 3 ; The travel path area for emergency equipment weighing less than 20 tons is 30m 2 The volume of printing material required is 30×(0.10+0.005×10+0.01×5)=6m 3 ; Other areas are for emergency personnel to enter, with an area of ​​65m 2 The volume of printing material required is 65×(0.10+0.005×10)=9.75m 3 ; The total volume of printed materials is 30.75m 3 .

[0080] By comparison, it is found that the two embodiments can save 56.7% and 65.8% of barrier materials respectively.

[0081] 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 to be protected.

Claims

1. A 3D printing method for emergency isolation barriers at contaminated sites, characterized in that: The following steps are involved: Step 10, collecting contaminated site information; the contaminated site information includes the distribution range of site pollution; types of pollutants and chemical and physical properties; Step 20, according to the contaminated site information collected in step 10, determine the construction parameters of the barrier; the construction parameters include printing boundary, printing thickness D , printing direction and printing order; Step 30, printing a barrier barrier above the contaminated site according to the construction parameters of the barrier barrier determined in step 20; The barrier has a layered structure and is composed of at least two layers, each layer of the barrier is composed of at least two printing strips; a reinforcement line is provided on the side of each printing strip, and a reinforcement net is provided on the bottom of each printing strip; In step 20, the printing thickness D According to formula (1), we can get: Formula (1) In the formula, D Indicates the printing thickness of the barrier, unit: m; n 1 represents the adjustment coefficient of on-site emergency personnel, unit: m / time, value range is 0.001~0.005; f 1 indicates the number of times emergency personnel enter the scene, unit: times; n 2 represents the adjustment coefficient of on-site emergency equipment with a mass less than 20 tons, unit: m / time, value range is 0.005~0.015; f 2 indicates the number of emergency equipment arrivals with a mass less than 20t, unit: times; M Indicates the mass of emergency equipment with a mass greater than or equal to 20t, unit: t; n 3 represents the adjustment coefficient of on-site emergency equipment greater than or equal to 20t, unit: m / (t×times), value range is 0.01~0.05; f 3 indicates the number of times emergency equipment weighing 20t or more enters the site, unit: times.

2. The method according to claim 1, characterized in that In step 20, the printing boundary is the boundary of the site pollution distribution range extending outward by 3 to 10 meters.

3. The method according to claim 1, characterized in that In step 20, the printing order is as follows: Step 201: Divide the printing area enclosed by the printing boundary into pieces, each piece being a square with a side length of L Calculate according to formula (2): Formula (2) In the formula, T Indicates the allowed printing time, unit: s; v 1 indicates the moving speed of the printing head of the printing machine, unit: m / s; v 2 represents the no-load moving speed of the print head of the printing machine, unit: m / s; w Indicates the width of the printing tape, unit: m; Step 202, printing a barrier layer by layer from bottom to top, printing at least 2 print strips on each layer, and then printing the previous layer until the barrier is printed; Step 203: Print the next barrier according to the method of step 202 until the printing is completed.

4. The method according to claim 3, characterized in that In step 202, when printing the previous layer, the time for the printing device to transfer from the printing end point of the next layer of barrier to the printing start point of the previous layer of barrier is called the allowed printing time. T , for the printable time of barrier materials t of m times; If the barrier is printed by a swing arm printing device, m The value of is 0.80~0.90; If the barrier is printed by a frame-type printing device, m The value is 0.85~0.

98.

5. The method according to claim 1, characterized in that In step 30, in two vertically adjacent layers of barrier barriers, the center line of each printing strip is opposite to the boundary of the vertically adjacent printing strip; the width of the printing strip is 10-30 cm.

6. The method according to claim 1, characterized in that In step 30, the reinforcement line is located at 1 / 2 of the height of the side of each printing belt, and an anti-slip line is provided on the reinforcement line.

7. The method according to claim 6, characterized in that The anti-slip line is perpendicular to the axis of the reinforcement line, and the length of the anti-slip line is 3 to 6 times the maximum particle size of the aggregate in the printing material; Anti-slip wire N The anti-skid lines are arranged in groups, each group of anti-skid lines includes 3 to 8 anti-skid lines, and the anti-skid lines are evenly distributed along the axis of the reinforcement line; the spacing between adjacent anti-skid lines is 1 to 3 times the length of the anti-skid line; In each group of anti-skid lines, the anti-skid lines are evenly distributed along the circumference of the reinforcement lines, the angles between adjacent anti-skid lines are equal, and the anti-skid lines and the reinforcement lines are three-dimensional.

8. The method according to claim 7, characterized in that In step 30, the reinforcement mesh is woven from reinforcement wires provided with anti-slip wires.

9. The method according to claim 8, characterized in that The grid of the reinforcing net is a square, and the side length of the grid is 0.2 to 0.6 times the width of the printing tape.

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