Manufacturing method of a filter structure that can replace sand and gravel materials

Abstract

The present invention discloses a manufacturing method of an anti-filter structure that can replace sand and gravel materials, including several anti-filter layers arranged coaxially from the inside to the outside. Each anti-filter layer is a three-dimensional porous grid structure of a spatial combination with different pore diameters. Each anti-filter layer is integrally in a tubular structure, and the equivalent pore diameter of the anti-filter layers from the outside to the inside gradually increases. The present invention can replace the existing sand and gravel anti-filter structure, has stable performance, good flexibility, and can adapt to soil deformation; has a light specific gravity and high strength, is convenient for on-site construction and installation, and can improve construction efficiency; can be mass-produced in a factory, has a low price and a high degree of standardization, and can reduce construction costs.

Description

Technical Field

[0001] The present invention relates to a manufacturing method of a filter structure that can replace sand and gravel, belonging to the technical field of filter structures. Background Art

[0002] A blind drain, also known as a subsurface drain, is used to drain groundwater and lower the groundwater level in some drainage systems with high drainage requirements. The structural forms of drainage blind drains are generally divided into two types: blind drains with drainage pipes and blind drains without drainage pipes. Among them, the blind drain without a drainage pipe is mostly a rock-filled structure, generally with a trapezoidal cross-section, and a sand and gravel filter layer is set. The purpose of the filter layer is to collect water flow and prevent soil particles from being blocked, that is, when the soil fluid passes through the filter layer, the filter layer intercepts the soil particles carried by the seepage flow and allows the fluid to pass through, that is, "retaining soil and filtering water". The blind drain with a drainage pipe is to add a drainage pipe to the blind drain on the basis of the blind drain without a drainage pipe, and a sand and gravel filter layer is set outside the drainage pipe. The drainage pipe can be selected from a flexible permeable pipe, a non-sand concrete infiltration pipe, a perforated corrugated pipe, a plastic blind pipe, etc.

[0003] As an effective engineering measure to prevent soil from undergoing seepage deformation, the filter layer is a transition layer set between two kinds of particles with a large difference in particle sizes of fine and coarse particles in a soil-rock structure, and is paved with sand and gravel with 2-3 layers of different particle sizes, the layer surface being nearly perpendicular to the seepage direction, and the particle size gradually increasing from small to large in the seepage direction. It is set at the seepage outlet, at the entrance of the drainage, and at the contact surface between the fine-grained soil and the coarser-grained material, etc.

[0004] However, in the actual use process, the blind drain with a traditional sand and gravel filter structure faces many problems, mainly as follows:

[0005] (1) The sand and gravel filter structure usually shows good use effects in the initial stage of the operation of the blind drain. However, with the passage of time, due to the influence of structural defects such as the self-weight of the soil layer and sand and gravel, and the influence of sediment impurities during the drainage process of the blind drain and uneven settlement caused by the rolling of the upper load, the pores of the sand and gravel in the filter layer become smaller and smaller, resulting in a gradual deterioration of the water supply and drainage capacity of the sand and gravel filter layer structure;

[0006] (2) In recent years, with the continuous deepening of the ecological civilization construction and the increase in environmental protection efforts, the extraction of natural resources such as river sand has been restricted or prohibited in various places, polluting and illegal sand and gravel enterprises have been shut down, resulting in an imbalance between supply and demand of sand and gravel. In some severely affected areas, the supply of sand and gravel is severely scarce or even out of stock, and the price of sand and gravel has skyrocketed, thus leading to a substantial increase in the cost of the blind drain with a traditional sand and gravel filter structure;

[0007] (3) The construction of the sand and gravel filter layer consumes a large amount of labor. The on-site construction requires excavating and backfilling a standard-shaped blind drain in cooperation with the laying of the drainage pipe, with a complex construction process, large labor consumption, and high cost. Summary of the Invention

[0008] In view of the problems existing in the above-mentioned prior art, the present invention provides an anti-seepage structure that can replace sand and gravel materials, which can replace the existing sand and gravel anti-seepage structure, has stable performance, good flexibility, and can adapt to soil deformation; has a light specific gravity and high strength, is convenient for on-site construction and installation, and can improve construction efficiency; can be mass-produced in factories, has a low price and a high degree of standardization, and can reduce construction costs.

[0009] To achieve the above object, the present invention adopts the following technical solution: An anti-seepage structure that can replace sand and gravel materials, the entire anti-seepage structure includes several anti-seepage layers arranged coaxially from the inside to the outside, and each anti-seepage layer is a three-dimensional porous grid structure of a spatial combination with different pore diameters. Each anti-seepage layer is integrally in a tubular structure, and the equivalent pore diameter of the anti-seepage layer from the outside to the inside gradually increases.

[0010] Preferably, it further includes a coating layer wrapped outside the outermost anti-seepage layer. The coating layer is a regular filter screen, that is, the coating layer is a filter screen with regular through holes opened above it, and the aperture of the through holes on the filter screen is not greater than the minimum equivalent pore diameter of the outermost anti-seepage layer. After adding the coating layer, the overall structure can ensure that most soil particles do not flow out, having both soil retention, that is, being able to intercept the fine particles lost in the foundation soil; and having sufficient water permeability to drain and decompress smoothly. Of course, if the particle size of the protected soil in the actual project is large or it is not easy to move in the direction of the water flow, the coating layer can also be omitted.

[0011] The outer contour of the entire anti-seepage structure can be determined according to the type of the anti-seepage layer of the blind ditch sand and gravel to be replaced. For example, if the type of the existing blind ditch sand and gravel anti-seepage layer is circular or trapezoidal, the outer contour shape of the entire anti-seepage structure is circular or trapezoidal.

[0012] The thickness of each anti-seepage layer is not less than 1 cm and not greater than 3 cm.

[0013] The equivalent pore diameter range of the outermost anti-seepage layer is 0 mm - 10 mm, and the porosity is 45% - 55%; the equivalent pore diameter range of the innermost anti-seepage layer is 10 mm - 20 mm, and the porosity is 85% - 95%.

[0014] A manufacturing method of an anti-seepage structure based on the above anti-seepage structure that can replace sand and gravel materials includes the following steps:

[0015] Step 1. Determine the anti-seepage structure: Determine the outer contour shape of the entire anti-seepage structure, the composite layer number of the anti-seepage layer as well as the inner radius of each anti-seepage layer , thickness , equivalent pore diameter and porosity , ;

[0016] Step 2: Add the raw materials and auxiliary materials into a mixer, stir and mix them evenly, and then feed them into an extruder by the mixer. The raw material is polypropylene, and the auxiliary material is carbon black masterbatch; the ratio of polypropylene to carbon black masterbatch is 100 kg: 2 - 3 kg;

[0017] Step 3: A spinneret is installed at the discharge end of the extruder. The shape of the spinneret is the same as the outer contour of the entire filter structure. The wire outlet holes of the extruded mixture are densely arranged in a layered and evenly distributed manner on the spinneret. The number of layers of the wire outlet holes on the spinneret is the same as the number of composite layers of the filter layer. The pore diameters of the wire outlet holes in each layer gradually increase from outside to inside;

[0018] Step 4: Extrude multiple thin filaments. The wire outlet speed of the spinneret is greater than the traction speed . The vertically extruded thin filaments enter the cavity of the forming die, are blocked and curled, and bond to each other to form a three-dimensional network body with different pore diameters; among them, the forming die is customized according to the filter structure type. If a filter structure replacing the filter layer type of the circular blind ditch gravel is manufactured, the forming die is circular; if a filter structure replacing the filter layer type of the trapezoidal blind ditch gravel is manufactured, the forming die is trapezoidal;

[0019] Step 5: The three-dimensional network body is shaped and cooled to be the finished product; if cutting is required, cut the required length according to the need; if arranging a coating layer is required, coat a filter mesh on the outside according to the need. The pore diameter on the filter mesh is not greater than the minimum equivalent pore diameter of the outermost filter layer.

[0020] In the above Step 1, if a filter structure replacing the filter layer type of the circular blind ditch gravel is manufactured, the outer contour of the entire filter structure is circular, the cross-section of each filter layer is circular ring-shaped, and the inner hollow radius of the entire filter structure (i.e., the inner radius of the innermost filter layer) is , and the outer contour radius is ;

[0021] If a filter structure replacing the filter layer type of the trapezoidal blind ditch gravel is manufactured, the outer contour of the entire filter structure is trapezoidal, the outermost filter layer is trapezoidal, the cross-section of each filter layer except the outermost layer is circular ring-shaped, and the inner hollow radius of the entire filter structure (i.e., the inner radius of the innermost filter layer) is , the radius of the inscribed circle in the outermost filter layer is , the upper side length of the outer contour of the outermost filter layer is , the lower side is , and the height is .

[0022] The thickness of each filter layer is not less than 1 cm and not more than 3 cm.

[0023] In the third step, if the outer contour of the entire filter structure is circular, the spinneret die is circular; if the outer contour of the entire filter structure is trapezoidal, the spinneret die is trapezoidal; the number of layers of the wire outlet holes on the spinneret die , the aperture of the wire outlet holes on the nth layer from the outside to the inside is for

[0024] , where n = 1, 2,..., m;

[0025] For the circular spinneret die, the number of the outermost layer of wire outlet holes is:

[0026] ,

[0027] The number of wire outlet holes on each layer of the circular spinneret die except the outermost layer, that is, the number of wire outlet holes on the nth layer from the outside to the inside is:

[0028] , ;

[0029] For the trapezoidal spinneret die, the number of the outermost layer of wire outlet holes is:

[0030] ,

[0031] The number of wire outlet holes in the ring between the inscribed circle of the outermost filter layer and the second filter layer from the outside to the inside of the trapezoidal spinneret die is:

[0032] ,

[0033] The number of wire outlet holes on each layer of the trapezoidal spinneret die except the outermost layer, that is, the number of wire outlet holes on the nth layer from the outside to the inside is:

[0034] , ;

[0035] where is a constant and is the aperture of the outermost layer of wire outlet holes; is a constant and is the aperture of the innermost layer of wire outlet holes.

[0036] In the fourth step, for the wire outlet speed of the circular spinneret die and the traction speed the relationship is: ; for the wire outlet speed of the trapezoidal spinneret die and the traction speed

[0037] Compared with the existing technologies, the present invention can replace the traditional sand and gravel filter structure, and has the advantages of stable performance and never degrading in the soil; good flexibility, capable of adapting to soil deformation, and avoiding the problem that the drainage capacity of the traditional sand and gravel filter layer structure is affected due to uneven settlement caused by the upper load; light specific gravity and high strength, convenient for on-site construction and installation, and greatly improving the construction efficiency; compared with the difficulty in obtaining traditional sand and gravel and the rising price, this three-dimensional structure can be mass-produced in the factory, with low price and high standardization degree, and can greatly reduce the construction cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic structural diagram of the present invention;

[0039] Figure 2 is Figure 1 the front view of

[0040] Figure 3 is Figure 2 the corresponding parameter representation diagram of

[0041] Figure 4 is another schematic structural diagram of the present invention;

[0042] Figure 5 is Figure 4 the front view of

[0043] Figure 6 is Figure 5 the corresponding parameter representation diagram of

[0044] In the figure: 1. outermost filter layer, 2. middle filter layer, 3. innermost filter layer, 4. coating layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following clearly and completely describes the technical solutions in the embodiments of the present invention with reference to the drawings. The described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0046] As Figures 1 to 6 shown, the present invention provides a filter structure that can replace sand and gravel. The entire filter structure includes several filter layers arranged coaxially from the inside to the outside. Each filter layer is a three-dimensional porous grid structure with different pore diameters in a spatial combination. Each filter layer is integrally in a tubular structure, and the equivalent pore diameter of the filter layer from the outside to the inside gradually increases. When in use, the entire filter structure is wrapped outside the drainage blind pipe and jointly forms an overall drainage blind ditch with the drainage blind pipe; the drainage blind pipe can be a plastic blind pipe, a perforated corrugated pipe or a flexible drainage pipe, etc.

[0047] The outer contour of the entire filter structure can be determined according to the type of the filter layer of blind ditch sand and gravel to be replaced. The existing types of the filter layer of blind ditch sand and gravel are circular or trapezoidal. Therefore, there are two types in the present invention. One is to replace the circular filter layer of blind ditch sand and gravel, and the outer contour shape of the entire filter structure is circular, as shown in Figure 1 , Figure 2 ; the other is to replace the trapezoidal filter layer of blind ditch sand and gravel, and the outer contour shape of the entire filter structure is trapezoidal, as shown in Figure 4 , Figure 5 ; the representation methods of the parameters in the two different types are shown in Figure 3 , Figure 6 .

[0048] The composite layer number of the above three-dimensional porous grid structure (i.e., the layer number of the filter layer) can be customized according to the actual engineering needs. Considering that the pore structure of the three-dimensional grid structure is extremely complex, with different pore sizes, connected and unconnected, open and closed, the image processing method is used to measure the equivalent pore diameter of the three-dimensional porous grid structure. The specific process is as follows:

[0049] Scan and process along the circumferential direction of the three-dimensional porous grid structure by using a scanner. Perform graying processing on the scanned image through computer image processing software, select an appropriate threshold for inverse selection, and a relatively clear pore distribution map can be obtained. Among them, the white area represents the three-dimensional porous grid structure, and the black area represents pores. Calculate the area of the black area respectively through the image processing software. The percentage of the area of the black area in the entire surface area is the porosity of the layer where the three-dimensional porous grid structure is located. Convert the black area into a circle with an equal area of a certain diameter, and the diameter of this circle is the equivalent pore diameter of the pore.

[0050] Taking layer composite layer number as an example, represents the equivalent pore diameter of the th filter layer from the outside to the inside, represents the porosity of the [[ID=n]] th filter layer from the outside to the inside, represents the thickness of the th filter layer from the outside to the inside, represents the inner radius of the

[0051] (1);

[0052] (2);

[0053] Among them, ; is the equivalent pore diameter of the outermost layer (n = 1) filter layer, and the range is 0 mm to 10 mm; is the equivalent aperture of the innermost (n = m) filter layer, with a range of 10 mm to 20 mm; is the porosity of the outermost (n = 1) filter layer, with a range of 45% - 55%; is the porosity of the innermost (n = m) filter layer, with a range of 85% - 95%.

[0054] The thickness of each of the said filter layers is not less than 1 cm and not greater than 3 cm.

[0055] As a further improvement of the present invention, it may further include a coating layer wrapped outside the outermost filter layer. The coating layer is a regular filter screen, that is, the coating layer is a filter screen with regular through - holes opened on the upper side. The aperture of the through - holes on the filter screen is not greater than the minimum equivalent aperture of the outermost filter layer. After adding the coating layer, the overall structure can ensure that most soil particles do not flow away, having both soil - retaining property, that is, it can intercept the fine particles lost in the base soil; and having sufficient water permeability to drain and decompress smoothly. Of course, if the particle size of the soil to be protected in the actual project is relatively large or not easy to move in the direction of the water flow, the coating layer can also be omitted.

[0056] A manufacturing method of an anti - filtering structure based on the above - mentioned replaceable sand and gravel materials includes the following steps:

[0057] Step 1. Determine the anti - filtering structure: Determine the outer contour shape of the entire anti - filtering structure, the composite layer number of the filter layer and the inner radius of each filter layer , thickness , equivalent aperture and porosity , ;

[0058] If manufacturing an anti - filtering structure to replace the filter layer type of a circular blind ditch sand and gravel material, the outer contour of the entire anti - filtering structure is circular, the cross - section of each filter layer is a circular ring, and the inner hollow radius of the entire anti - filtering structure (i.e., the inner radius of the innermost filter layer) is , and the outer contour radius is ;

[0059] If manufacturing an anti - filtering structure to replace the filter layer type of a trapezoidal blind ditch sand and gravel material, the outer contour of the entire anti - filtering structure is trapezoidal, the outermost filter layer is trapezoidal, the cross - section of each filter layer except the outermost layer is a circular ring, the inner hollow radius of the entire anti - filtering structure (i.e., the inner radius of the innermost filter layer) is , the radius of the inscribed circle in the outermost filter layer is , the upper side length of the outer contour of the outermost filter layer is , the lower side is , and the height is ;

[0060] Step 2: Add the raw materials and auxiliary materials to a mixer, stir and mix them evenly, and feed the mixture into an extruder by the mixer. The raw material is polypropylene, and the auxiliary material is carbon black masterbatch. The ratio of polypropylene to carbon black masterbatch is 100 kg: 2 - 3 kg. There are five heating zones in the extruder. The temperature of the heating zone closest to the feeding end is 150 °C, and the temperature of each heating zone increases by 10 °C from the feeding end to the discharging end direction. The temperature in the area near the discharging end is maintained at the melting point temperature of the raw materials (i.e., the raw materials and auxiliary materials).

[0061] Step 3: A spinneret is installed at the discharging end of the extruder. The shape of the spinneret is the same as the outer contour of the entire filter structure. If the outer contour of the entire filter structure is circular, the spinneret is circular; if the outer contour of the entire filter structure is trapezoidal, the spinneret is trapezoidal. The wire outlet holes of the extruded mixture are densely arranged in a layered and evenly distributed manner on the spinneret. The number of layers of the wire outlet holes on the spinneret is the same as the number of composite layers of the filter layer, that is ; The aperture of each layer of wire outlet holes gradually increases from outside to inside. The aperture of the nth layer of wire outlet holes from outside to inside is: the aperture is:

[0062] (3),

[0063] where , is the aperture of the outermost layer (n = 1) of wire outlet holes and is a constant; is the aperture of the innermost layer (n = m) of wire outlet holes and is a constant;

[0064] For a circular spinneret, the number of the outermost layer of wire outlet holes is:

[0065] (4),

[0066] The number of wire outlet holes of the remaining layers in the circular spinneret except the outermost layer, that is, the number of wire outlet holes of the nth layer from outside to inside is:

[0067] (5), ;

[0068] For a trapezoidal spinneret, the number of the outermost layer of wire outlet holes is:

[0069] (6),

[0070] The number of wire outlet holes in the circular ring between the inscribed circle in the outermost anti-filter layer and the second anti-filter layer from the outside to the inside in the trapezoidal spinneret die is:

[0071] (7),

[0072] The number of wire outlet holes in each layer of the trapezoidal spinneret die except the outermost layer, that is, the number of wire outlet holes in the nth layer from the outside to the inside is:

[0073] (8), .

[0074] Step Four: Extrude multiple fine filaments, and the wire outlet speed of the spinneret die is greater than the traction speed , and the vertically extruded fine filaments enter the cavity of the forming die, are blocked and curled, and bond with each other to form a three-dimensional network body with different pore diameters; among them, the forming die is customized according to the anti-filter structure type. If an anti-filter structure replacing the circular blind ditch gravel anti-filter layer type is manufactured, the forming die is circular; if an anti-filter structure replacing the trapezoidal blind ditch gravel anti-filter layer type is manufactured, the forming die is trapezoidal;

[0075] Among them, for the wire outlet speed of the circular spinneret die and the traction speed The relationship is:

[0076] (9);

[0077] For the wire outlet speed of the trapezoidal spinneret die and the traction speed The relationship is:

[0078] (10).

[0079] Step Five: The three-dimensional network body is shaped and cooled to be the finished product; if cutting is required, cut the required length as needed; if arranging a coating layer is required, coat a filter mesh on the outside as needed, and the pore diameter on the filter mesh is not greater than the minimum equivalent pore diameter of the outermost anti-filter layer.

[0080] The thickness of each anti-filter layer is not less than 1 cm and not more than 3 cm.

[0081] Example 1:

[0082] Given: The type of the blind ditch gravel anti-filter layer to be replaced is circular, and the outer diameter of the drainage blind pipe to be wrapped is 70 mm

[0083] Design: Circular anti-filter structure, the number of composite layers m = 3, and the outer contour radius of the entire anti-filter structure = 100 mm, the inner hollow radius (i.e., the inner radius of the innermost filter layer) is = 70 mm, and the thickness of each layer is 10 mm. The inner radius of the first filter layer from the outside to the inside = 90 mm, and the inner radius of the second filter layer from the outside to the inside = 80 mm; the equivalent pore size of the outermost layer (n = 1) is the smallest, is 5 mm, and the porosity Q1 is 50%; the equivalent pore size of the innermost layer (n = 3) is the largest, is 15 mm, and the porosity Q3 is 90%;

[0084] Then the equivalent pore size of the middle layer (n = 2) ;

[0085] The porosity .

[0086] A circular spinneret die head is selected, and the number of layers of the pore diameter of the die head is 3 layers; the pore diameter of the outermost layer of the die head = 0.4 mm, and the pore diameter of the innermost layer of the die head = 0.8 mm,

[0087] Then the pore diameter of the middle layer of the die head = 0.6 mm,

[0088] The number of the outermost layer of die head pores = 119;

[0089] The number of pores in the middle layer (the second layer from the outside to the inside) of the die head

[0090]

[0091] = 66;

[0092] The number of pores in the innermost layer (the third layer from the outside to the inside) of the die head

[0093] = 42.

[0094] A circular forming die is selected. There is a die cavity on the forming die that is matched with the circular spinneret die head. The die cavity is also arranged in layers, and its specific dimensions are matched with the circular filter structure to be produced. For example, the die cavity is also divided into three layers from the outside to the inside, and the dimensions of each layer of the die cavity are the same as those of the corresponding layer of the filter layer in the circular filter structure to be produced, ensuring that the filaments pulled out in the same layer are blocked and curled in the die cavity.

[0095] The relationship between the die head wire drawing speed and the traction speed ≈ 210.

[0096] According to the above design specifications, and by using the above circular spinneret and forming die, manufacturing according to the above manufacturing method can achieve the required product.

[0097] Example 2:

[0098] Given: The type of the replacement blind ditch gravel filter layer is trapezoidal, and the outer diameter of the drainage blind pipe to be wrapped is 60 mm

[0099] Considering the force stability and processing convenience, the trapezoid is an isosceles trapezoid. Due to the special nature of the isosceles trapezoid structure, the equivalent pore size and porosity of the outermost filter layer can be based on its inscribed circle.

[0100] Design: Trapezoidal filter structure, the radius of the inscribed circle in the outermost filter layer of the entire filter structure = 100 mm, the inner hollow radius (i.e., the inner radius of the innermost filter layer) is = 60 mm, the upper side length of the outer contour of the outermost filter layer is = 300 mm, the lower side is = 220 mm, the height = = 200 mm; the number of composite layers m = 3, and the thicknesses of the 1st, 2nd, and 3rd filter layers from the outside to the inside are = 15 mm, = 10 mm, = 15 mm, the inner radius of the 1st filter layer from the outside to the inside = 85 mm, the inner radius of the 2nd filter layer from the outside to the inside = 75 mm; the equivalent pore size of the outermost layer (n = 1) is the smallest, between 0 mm and 10 mm, and the porosity is 45%; the equivalent pore size of the innermost layer (n = 3) is the largest, between 10 mm and 20 mm, and the porosity is 95%;

[0101] Then the equivalent pore size of the middle layer (n = 2) , which is between 4 mm and 14 mm;

[0102] The porosity .

[0103] Select a trapezoidal spinneret, and the number of layers of the spinneret hole aperture is 3 layers; the aperture of the outermost spinneret hole = 0.4 mm, the aperture of the innermost spinneret hole = 0.8 mm,

[0104] Then the aperture of the middle spinneret hole = 0.56 mm,

[0105] The number of wire outlet holes in the outermost layer

[0106] = 586,

[0107] The wire outlet holes on the outermost layer are evenly distributed within the cross-section of the entire outermost layer;

[0108] Calculate the number of wire outlet holes in the circular ring between the inscribed circle in the outermost layer of the filter layer and the second layer of the filter layer from the outside to the inside = 174;

[0109] The number of wire outlet holes in the middle layer (the second layer from the outside to the inside)

[0110]

[0111] = 73;

[0112] The number of wire outlet holes in the innermost layer (the third layer from the outside to the inside)

[0113] = 67.

[0114] Select a trapezoidal forming die. The forming die is provided with a die cavity that matches the trapezoidal spinneret die head. The die cavity is also arranged in layers, and its specific dimensions are matched with the trapezoidal filter structure to be produced. For example, the die cavity is also divided into three layers from the outside to the inside, and the dimensions of each layer of the die cavity are the same as those of the corresponding layer of the filter layer in the trapezoidal filter structure to be produced, ensuring that the fine wires pulled out in the same layer are blocked and curled in the die cavity.

[0115] The relationship between the wire outlet speed of the die head and the traction speed ≈ 179.

[0116] According to the above design specifications, and using the above trapezoidal spinneret die head and forming die, manufacturing according to the above manufacturing method can achieve the required product.

[0117] Example 3:

[0118] Known: The type of the filter layer to replace the blind ditch gravel is circular, and the outer diameter of the drainage blind pipe to be wrapped is 60 mm, that is, the radius of the innermost layer of the filter layer in the entire structure is the same. The performance comparison of the filter layer with different numbers and thicknesses is shown in Table 1 below:

[0119] Table 1

[0120]

[0121] Comparing and analyzing Table 1, it can be seen that for filter structures with the same inner diameter, the more layers there are, the better the filtering performance and the higher the cost.

[0122] Example 4:

[0123] It is known that the type of the filter layer to replace the blind ditch sand and gravel is circular, and the radius of the outermost filter layer in the whole structure = 100 mm is the same. The performance comparison of the filter layer with different numbers of layers and thicknesses is shown in Table 2 below:

[0124] Table 2

[0125]

[0126] From the comparative analysis of Table 2, it can be seen that for the filter structures with the same external dimensions, their drainage capacity is proportional to the inner diameter. The larger the inner diameter, the greater the drainage capacity. When the porosity inside and outside the whole filter structure is determined, the more the number of layers, the better its filtering performance.

[0127] In summary, the present invention has the advantages of never degrading in the soil body and having stable performance; good flexibility, being able to adapt to the deformation of the soil body, and avoiding the problem that the water supply and drainage capacity of the filter layer structure is changed due to uneven settlement caused by the upper load of the traditional sand and gravel filter layer; light specific gravity and high strength, being convenient for on-site construction and installation, and greatly improving the construction efficiency; compared with the difficulty in obtaining traditional sand and gravel and the rising price, this three-dimensional structure can be mass-produced in the factory, with low price and high standardization degree, and can greatly reduce the construction cost.

[0128] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit and basic characteristics of the present invention. In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A manufacturing method of an anti-filter structure that can replace sand and gravel materials, characterized in that, Including the following steps: Step 1. Determine the filter structure: Determine the outer contour shape of the entire filter structure, the number of composite layers of the filter layer and the inner radius of each filter layer , thickness , equivalent pore size and porosity , ; Step 2: Add the raw materials and auxiliary materials into a mixer, stir and mix them evenly, and then feed them into an extruder by the mixer. The raw material is polypropylene, and the auxiliary material is carbon black masterbatch. The ratio of polypropylene to carbon black masterbatch is 100 kg: 2 - 3 kg. Step 3: A spinneret die is installed at the discharge end of the extruder. The shape of the spinneret die is the same as the outer contour of the entire filter structure. The wire outlet holes of the extruded mixture are densely arranged in a layered and evenly distributed manner on the spinneret die. The number of layers of the wire outlet holes on the spinneret die is the same as the number of composite layers of the filter layer. The aperture of the wire outlet holes in each layer gradually increases from the outside to the inside. Step 4: Extrude multiple filaments, and the filament extrusion speed of the spinneret is greater than the traction speed , and the vertically extruded filaments enter the cavity of the forming die, are blocked and curled, and adhere to each other to form a three-dimensional network body with different pore diameters; among them, the forming die is customized according to the filter structure type. If a filter structure is manufactured to replace the filter layer type of the gravel filter layer of the circular blind ditch, the forming die is circular; if a filter structure is manufactured to replace the filter layer type of the gravel filter layer of the trapezoidal blind ditch, the forming die is trapezoidal; Step 5: The three-dimensional network is shaped and cooled to obtain the finished product. If cutting is required, cut the required length as needed. If a coating layer needs to be arranged, coat the outside with a filter screen as needed. The aperture of the filter screen is not larger than the minimum equivalent aperture of the outermost filter layer.

2. The manufacturing method of an anti-filter structure capable of replacing sand and gravel materials according to claim 1, characterized in that, In the first step, if an anti-filter structure is manufactured to replace the gravel anti-filter layer type of the circular blind ditch, the outer contour of the entire anti-filter structure is circular, the cross-section of each anti-filter layer is circular ring-shaped, and the inner hollow radius of the entire anti-filter structure is , and the outer contour radius is ; If an anti-filter structure is manufactured to replace the trapezoidal blind ditch gravel anti-filter layer type, the outer contour of the entire anti-filter structure is trapezoidal, the outermost anti-filter layer is trapezoidal, and the cross-sections of each anti-filter layer except the outermost layer are circular rings. The inner hollow radius of the entire anti-filter structure is , the radius of the inscribed circle in the outermost anti-filter layer is , the upper side length of the outer contour of the outermost anti-filter layer is , the lower side is , and the height is .

3. The manufacturing method of an anti-filter structure capable of replacing sand and gravel materials according to claim 1, characterized in that, The thickness of each filter layer is not less than 1 cm and not more than 3 cm.

4. The manufacturing method of an anti-filter structure capable of replacing sand and gravel materials according to claim 3, characterized in that In the third step, if the outer contour of the entire filter structure is circular, the spinneret die is circular; if the outer contour of the entire filter structure is trapezoidal, the spinneret die is trapezoidal; the number of layers of the wire outlet holes on the spinneret die , the aperture of the wire outlet holes on the nth layer from the outside to the inside is as follows: , where n = 1, 2,..., m; For a circular spinneret die, the number of the outermost filament holes is as follows: ， The number of spinneret holes in each layer of the circular spinneret die except the outermost layer, that is, the number of spinneret holes in the nth layer from the outside to the inside is as follows: ， ； For a trapezoidal spinneret die, the number of the outermost filament holes is as follows: ， The number of wire outlet holes in the ring between the inscribed circle of the outermost filter layer and the second layer of the filter layer from the outside to the inside in the trapezoidal spinneret die is: ， The number of wire outlet holes in each layer of the trapezoidal spinneret die except the outermost layer, that is, the number of wire outlet holes in the nth layer from the outside to the inside is: ， ； Among them, is a constant and is the aperture of the outermost wire outlet hole; is a constant and is the aperture of the innermost wire outlet hole.

5. The manufacturing method of an anti-filter structure capable of replacing sand and gravel materials according to claim 4, characterized in that, In the fourth step, for the wire drawing speed of the circular spinneret die and the drawing speed the relationship is: ; for the wire drawing speed of the trapezoidal spinneret die and the drawing speed the relationship is: .

Images