Environmentally friendly air film for foundation pit construction and preparation method thereof

Abstract

The present invention relates to the technical field of air film preparation, and in particular to an environmentally friendly air film for foundation pit construction and a preparation method thereof, the method comprising: performing a test cutting of a test air film; determining an air film cutting processing method based on the edge damage length of the test air film; determining a cutting parameter adjustment method based on the edge damage length and the number of edge damage sections in a section corresponding to the edge damage length; performing a second test cutting of the test air film; if the edge damage length meets the requirements and the number of edge damage sections does not meet the requirements, adjusting the number of seams; if the edge damage length does not meet the requirements, repeating the above steps until the edge damage length of the air film meets the requirements; cutting the air film to obtain air film slices; and heat-sealing the air film slices to obtain a finished air film. The present invention improves the load-bearing capacity and stability of the air film.

Description

Technical Field

[0001] The present invention relates to the technical field of air film preparation, and in particular to an environmentally friendly air film for foundation pit construction and a preparation method thereof. Background Art

[0002] In the existing technology, the foundation pit air film process technology can effectively isolate the impact of dust on the outer periphery of the air film during construction work in the foundation pit due to the closed operation in the air film. The foundation pit air film process technology also has a certain effect on noise reduction. The environmentally friendly air film for foundation pit construction is a temporary structure used for foundation pit support and waterproofing. It uses inflation technology to form an inflatable membrane structure to achieve the purpose of protecting the foundation pit and preventing soil erosion; the environmentally friendly air film is usually made of high-strength and durable synthetic materials, such as polyester fiber, PVC coated fabric, etc. These materials have good tear resistance and aging resistance, and can be recycled, meeting environmental protection requirements.

[0003] Chinese Patent Publication No. CN116791807A discloses a large-curvature, large-span, multi-layer ETFE inflatable membrane structure and its construction method, characterized by assembling the roof, sliding the arch beam structure into place, welding and coating it for reinforcement and stabilization; optimizing the ETFE membrane structure, performing form-finding analysis, load analysis, and cutting analysis; installing an intelligent inflation system, and connecting the ETFE membrane structure to the arch beam. This large-curvature, large-span, multi-layer ETFE inflatable membrane structure and its construction method suffer from the problem that the uneven material quality of the membrane and the uneven thickness and texture of the different materials lead to the influence of different layer stresses during the cutting process, resulting in difficulty in controlling the damaged length of the membrane edge, which in turn leads to a decrease in the mechanical performance of the inflatable structure at the cutting position. Summary of the Invention

[0004] To this end, the present invention provides an environmentally friendly air film for foundation pit construction and a preparation method thereof, so as to overcome the problem in the prior art that the air film is affected by different layers of stress during the cutting process due to the uneven material inside the air film and the uneven thickness and texture of different materials, resulting in the edge of the air film being damaged and the length being difficult to control, thereby causing the mechanical properties of the air mold structure to deteriorate at the cutting position.

[0005] To achieve the above object, the present invention provides a method for preparing an environmentally friendly air film for foundation pit construction, comprising:

[0006] Step S1, performing a test cutting on the air film to obtain a test air film;

[0007] Step S2, determining the air film cutting method according to the damaged length of the edge of the test air film, including adjusting the cutting method from unidirectional cutting to bidirectional cutting,

[0008] Alternatively, the cutting speed is adjusted according to the vibration intensity of the test air film;

[0009] Step S3, determining a cutting parameter adjustment method according to the damaged edge length and the number of damaged edge sections, including adjusting the number of cutting layers or adjusting the cutting angle;

[0010] Step S4, performing a secondary test cutting on the test air film according to the air film cutting processing method and the cutting parameter adjustment method;

[0011] Step S5: If the edge damaged length meets the requirement and the number of edge damaged sections does not meet the requirement, the number of seams is adjusted and step S6 is executed after the number of seams is adjusted. If the edge damaged length does not meet the requirement, steps S1-S4 are repeated until the edge damaged length of the air film meets the requirement.

[0012] Step S6, actually cutting the air film according to the air film cutting processing method and the cutting parameter adjustment method to output air film slices;

[0013] Step S7, performing heat merging and cooling on the air film slices according to the execution result of step S5 to obtain a finished air film;

[0014] The time interval between heat sealing and cooling is determined according to the difference in expansion speed of the air film between the high stress area and the low stress area in the heat sealing.

[0015] Furthermore, in step S2, adjusting the cutting mode from unidirectional cutting to bidirectional cutting includes:

[0016] Performing image analysis on the test air film to obtain the damaged length of the edge;

[0017] comparing the damaged length of the edge with a preset length;

[0018] If the damaged length of the edge is greater than the preset length, it is determined that the consistency between the edge and the internal texture structure of the test air membrane does not meet the requirements, and a two-way cutting method is adopted;

[0019] The edge damaged length is the sum of the lengths of the edges that are damaged or deformed.

[0020] Furthermore, in step S2, adjusting the cutting speed includes:

[0021] If the consistency of the test air film does not meet the requirements and the test air film does not have a bidirectional cutting condition, obtaining a minimum value of the vibration intensity of the test air film during the one test cutting;

[0022] Adjusting the cutting speed of the test air film that does not meet the bidirectional cutting condition to the cutting speed when the vibration intensity is the minimum value;

[0023] The condition that the test air film does not have bidirectional cutting is that the cutting length of the test air film is less than a preset cutting length.

[0024] Furthermore, in step S3, adjusting the number of cropping layers includes:

[0025] Obtaining the number of the edge damaged sections;

[0026] comparing the number of the edge damaged sections with a preset number;

[0027] If the number of the edge damaged sections is greater than the preset number, it is determined that the shear stress of the test air film does not meet the requirement, and the number of shear layers is increased.

[0028] Furthermore, the number of cutting layers is positively correlated with the number of edge damaged sections.

[0029] Furthermore, in step S3, adjusting the cropping angle includes:

[0030] If the number of the edge damaged sections is less than or equal to the preset number, it is determined that the shear stress of the test air film meets the requirements, and the shear angle is reduced.

[0031] The cutting angle is the angle between the main back surface of the cutting knife and the surface of the air film; and the cutting angle is negatively correlated with the edge damaged length.

[0032] Furthermore, in step S5, adjusting the number of seams includes:

[0033] Obtaining the density of damaged positions within a unit edge damaged length of the test air film;

[0034] If the density is greater than a preset density, the area within the unit edge damaged length is determined to be a high stress area;

[0035] If the density is less than or equal to the preset density, the area within the unit edge damaged length is determined to be a low stress area;

[0036] The number of seams at the edge of the air film corresponding to the high stress area is reduced.

[0037] The number of seams is negatively correlated with the density.

[0038] Furthermore, the time interval between the heat sealing and the cooling is determined according to the difference in expansion speed of the air film between the high stress area and the low stress area in the heat sealing, including:

[0039] respectively obtaining average expansion speeds of the air films in the high stress area and the low stress area during heat sealing, and calculating a difference in the expansion speeds of the air films;

[0040] If the difference is greater than a preset difference, it is determined that the degree of fusion does not meet the requirements, and the time interval between the heat sealing and cooling is increased.

[0041] Furthermore, the time interval between heat sealing and cooling is positively correlated with the difference.

[0042] The present invention also provides an environmentally friendly air film for foundation pit construction, wherein the components of the environmentally friendly air film include: a PVDF coating as a self-cleaning layer, a PVC coating, an adhesive layer, and a substrate.

[0043] The order of the constituent materials of each layer of the environmentally friendly air film from top to bottom is PVDF coating-PVC coating-adhesive layer-base material-adhesive layer-PVC coating-PVDF coating;

[0044] An anti-UV layer is further provided between the PVDF coating and the adjacent PVC coating.

[0045] Compared with the prior art, the beneficial effect of the present invention is that the method of the present invention determines the consistency between the edge and the internal texture structure of the air film and the shearing stress by performing a test cut on the air film. Since the air film is made of multiple layers of materials, the physical properties and thickness of each layer of material vary greatly, resulting in extremely uneven internal stress distribution of the air film. This unevenness further aggravates the degree of damage to the edge of the air film during the cutting process. The air film structure relies on the tension generated by its internal inflation to maintain its shape and stability. If the internal texture structure of the air film is poorly uniform, it will lead to uneven local tension distribution, which will affect the overall structural performance of the air film. In the corners or edge areas of the air film, if the texture structure after cutting is inconsistent with the interior, these areas will be more prone to wrinkles. Wrinkles or relaxation phenomena will be avoided, thereby reducing the bearing capacity of the air film. By determining the secondary test cutting of the test air film, the accuracy and reliability of cutting will be increased. After the first test cutting, the consistency between the edge and the internal texture structure of the air film and the shearing stress will be evaluated. The secondary test cutting can further refine the cutting parameters to ensure that the consistency between the corner or edge area of ​​the air film and the internal texture structure after cutting meets the requirements, reducing the occurrence of wrinkles or relaxation phenomena, and realizing the improvement of the bearing capacity and overall structural performance of the air film. The secondary test cutting also takes into account the uneven stress inside the air film. By adjusting the number of seams, the problem of damage to the air film caused by uneven stress distribution is reduced, and the long-term stability and durability of the environmentally friendly air film in foundation pit construction are improved.

[0046] Furthermore, the method of the present invention determines the consistency between the edge and the internal texture structure by setting a preset length. Since the stronger the consistency between the cutting position and the internal texture structure of the air film after cutting, the more internal parts will be affected after the edge is cut. If there is inconsistency, the air film at the cutting position will be more susceptible to damage during cutting, resulting in edge breakage and deformation, which will have a negative impact on the subsequent heat sealing and seam quality. By measuring the edge of the air film after cutting, comparing it with the preset length, and adjusting the cutting parameters, a quantitative assessment of the degree of damage to the air film edge is achieved.

[0047] Furthermore, the method of the present invention determines the shear stress of the air membrane by setting a preset number. Since the internal stress distribution of the air membrane during the cutting process is uneven, the stress is discontinuous, which leads to an increase in the number of damaged edge sections. The discontinuous stress causes stress concentration at the cutting edges or seams of the air membrane, increasing the risk of cracking and damage of the air membrane, thereby affecting the bearing capacity of the membrane structure. During the long-term use of the membrane structure, the air membrane will gradually deform and relax, affecting the stability of the membrane structure. By analyzing the shear stress of the air membrane, the bearing capacity of the air membrane is improved.

[0048] Furthermore, the method of the present invention adopts two-way cutting for the air membrane whose consistency does not meet the requirements and has the conditions for two-way cutting, so as to avoid damage to the internal structure caused by the stress generated in one direction, and effectively disperses the stress generated in the cutting process, thereby achieving the improvement of the stability of the overall structure of the air membrane after cutting; by adjusting the cutting speed of the air membrane whose consistency does not meet the requirements and does not have the conditions for two-way cutting to the cutting speed when the vibration intensity is minimum, the minimum damage to the air membrane during the cutting process is achieved, the risk of cracking and damage of the air membrane due to excessive cutting stress is reduced, and the integrity of the air membrane is ensured. At the same time, it can also improve the flatness of the edge of the air membrane after cutting, reduce the difficulty of subsequent heat sealing and seaming, and further achieve the improvement of the stability and bearing capacity of the membrane structure.

[0049] Furthermore, the method described herein increases the number of cutting layers for air films that do not meet the required consistency or shear stress. Because air films lack continuous stress, this stress is suppressed by adding more layers, thereby reducing the risk of cracking and damage. Increasing the number of cutting layers also enhances the strength and toughness of the air film, improves its sealing performance, and reduces air leakage, ultimately improving the effectiveness of environmentally friendly air films used in foundation pit construction.

[0050] Furthermore, the method of the present invention reduces the cutting angle of the air film whose consistency does not meet the requirements but whose cutting stress meets the requirements, so as to change the direction of the stress line and reduce the concentration of stress. It can also make the edge of the air film smoother after cutting, reduce the difficulty of subsequent processing, and achieve improved production efficiency.

[0051] Furthermore, the method of the present invention reduces the number of seams at the edge of the air membrane corresponding to the high stress area to reduce stress concentration at the seams, making the air membrane more uniform when subjected to stress, thereby improving the strength and stability of the seams. The reduction in the number of seams can also reduce the risk of air leakage at the seams, further improving the sealing performance and bearing capacity of the membrane structure, avoiding the decrease in strength and damage of the air membrane due to continuous seams at stress positions, and achieving improved stability of the environmentally friendly air membrane used for foundation pit construction.

[0052] Furthermore, the method of the present invention sets a preset difference amount, and when it is determined that the degree of fusion does not meet the requirements, the time interval between heat sealing and cooling is increased to reduce the structural mutation caused by the small time interval, which may cause the high stress area to be damaged again, thereby improving the strength and sealing performance of the air film.

[0053] Furthermore, the method of the present invention sets the materials of the environmentally friendly air film as PVDF coating, PVC coating, adhesive layer, and substrate, and there is an anti-UV layer between the self-cleaning layer on the surface and the PVC layer. This layer of material mainly blocks the damage of ultraviolet rays to PVC and prevents the breakage of the PVC molecular structure. The material without PVDF will turn yellow and easily accumulate dust after a period of use. The addition of PVDF can improve the self-cleaning ability, and the PVC coating increases the good waterproof and moisture-proof properties of the air film, ensuring the dryness of the internal environment of the foundation pit. The setting of the adhesive layer makes the layers of materials tightly combined, avoids the occurrence of interlayer peeling, and realizes the improvement of the stability of the air film. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is an overall flow chart of a method for preparing an environmentally friendly air film for foundation pit construction according to an embodiment of the present invention;

[0055] Figure 2 A flow chart of adjusting the cutting mode from one-way cutting to two-way cutting in a method for preparing an environmentally friendly air film for foundation pit construction according to an embodiment of the present invention;

[0056] Figure 3 This is a flow chart of adjusting and cutting the number of layers in a method for preparing an environmentally friendly air membrane for foundation pit construction according to an embodiment of the present invention;

[0057] Figure 4 This is a test cutting logic diagram of the method for preparing an environmentally friendly air film for foundation pit construction according to an embodiment of the present invention. DETAILED DESCRIPTION

[0058] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0059] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0060] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0061] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0062] See also Figure 1 、 Figure 2 、 Figure 3 as well as Figure 4 As shown, they are respectively an overall flow chart of the method for preparing an environmentally friendly air film for foundation pit construction according to an embodiment of the present invention, a flow chart for adjusting the cutting method from one-way cutting to two-way cutting, a flow chart for adjusting the number of cutting layers, and a logic diagram for a single test cutting. A method for preparing an environmentally friendly air film for foundation pit construction according to an embodiment of the present invention comprises:

[0063] Step S1, performing a test cutting on the air film to obtain a test air film;

[0064] Step S2, determining the air film cutting method according to the damaged length of the edge of the test air film, including adjusting the cutting method from unidirectional cutting to bidirectional cutting,

[0065] Alternatively, the cutting speed is adjusted according to the vibration intensity of the test air film;

[0066] Step S3, determining a cutting parameter adjustment method according to the damaged edge length and the number of damaged edge sections, including adjusting the number of cutting layers or adjusting the cutting angle;

[0067] Step S4, performing a secondary test cutting on the test air film according to the air film cutting processing method and the cutting parameter adjustment method;

[0068] Step S5: If the edge damaged length meets the requirement and the number of edge damaged sections does not meet the requirement, the number of seams is adjusted and step S6 is executed after the number of seams is adjusted. If the edge damaged length does not meet the requirement, steps S1-S4 are repeated until the edge damaged length of the air film meets the requirement.

[0069] Step S6, actually cutting the air film according to the air film cutting processing method and the cutting parameter adjustment method to output air film slices;

[0070] Step S7, performing heat merging and cooling on the air film slices according to the execution result of step S5 to obtain a finished air film;

[0071] The time interval between heat sealing and cooling is determined according to the difference in expansion speed of the air film between the high stress area and the low stress area in the heat sealing.

[0072] Specifically, the damaged edge length and the number of damaged edge sections are detected by an industrial camera disposed above the cut edge of the test air film.

[0073] Specifically, the equipment for cutting the air film is an automated cutting machine. In step S7, the CAD drawing of the air film is imported into the automated cutting machine and the air film is cut according to the shape and size in the CAD drawing. The automated cutting machine can adjust the cutting angle.

[0074] Specifically, the test cutting is to use an automated cutting machine to perform a straight-line cutting of the air film along a diagonal line or a symmetrical axis according to actual cutting standards.

[0075] Specifically, the number of cutting layers of the air film is adjusted by the distance between the dynamic feed roller and the fixed feed roller of the automatic cutting machine. The number of cutting layers of the air film is the number of air films stacked when the air film is cut once in the automatic cutting machine.

[0076] Specifically, the cutting angle is adjusted by a transmission device of a transmission mechanism connecting the automatic cutting machine and the cutting knife, and the specific adjustment method is to adjust the depth of the transmission shaft in the coupling in the transmission device.

[0077] Specifically, in step S7, the equipment for heat sealing the air film is a high-frequency heat sealing machine; the general value range of the heat sealing temperature is [240°C, 280°C], and the preferred embodiment of the heat sealing temperature is 260°C; the general value range of the heat sealing time is [1s, 1.6s], and the preferred embodiment of the heat sealing time is 1.4s.

[0078] Specifically, one-way cutting is the cutting knife of the cutting machine performing one-way cutting on the same cutting line.

[0079] Specifically, bidirectional cutting is when the cutting knives of a cutting machine perform opposite-direction cutting on the same cutting line.

[0080] During implementation, the method of the present invention performs a test cut on the air film, and then determines the consistency of the edge and internal texture structure of the air film and the shearing stress. Since the air film is made of multiple layers of materials, the physical properties and thickness of each layer of material vary greatly, resulting in extremely uneven internal stress distribution of the air film. This unevenness further aggravates the degree of damage to the edge of the air film during the cutting process. The air film structure relies on the tension generated by its internal inflation to maintain its shape and stability. If the internal texture structure of the air film is poorly uniform, it will lead to uneven local tension distribution, which will affect the overall structural performance of the air film. In the corners or edge areas of the air film, if the texture structure after cutting is inconsistent with the interior, these areas will be more prone to wrinkles or sagging. Thereby reducing the bearing capacity of the air film, by determining the secondary test cutting of the test air film, thereby increasing the accuracy and reliability of cutting, after the first test cutting, on the basis of evaluating the consistency between the edge and the internal texture structure of the air film and the shearing stress, the secondary test cutting can further refine the cutting parameters to ensure that the consistency of the air film after cutting with the internal texture structure in the corner or edge area meets the requirements, reducing the occurrence of wrinkles or relaxation, and realizing the improvement of the bearing capacity and overall structural performance of the air film; the secondary test cutting also takes into account the uneven stress inside the air film, and by adjusting the number of joints, reduces the problem of damage to the air film caused by uneven stress distribution, and realizes the improvement of the long-term stability and durability of the environmentally friendly air film in foundation pit construction.

[0081] Specifically, in step S2, adjusting the cutting mode from unidirectional cutting to bidirectional cutting includes:

[0082] Performing image analysis on the test air film to obtain the damaged length of the edge;

[0083] comparing the damaged length of the edge with a preset length;

[0084] If the damaged length of the edge is greater than the preset length, it is determined that the consistency between the edge and the internal texture structure of the test air membrane does not meet the requirements, and a two-way cutting method is adopted;

[0085] The edge damaged length is the sum of the lengths of the edges that are damaged or deformed.

[0086] Specifically, the length of the damaged or deformed edge is the straight-line distance between the two end positions of the damaged or deformed edge region on the air film.

[0087] Specifically, the preset length is equal to the product of the length of the cropped edge and the bidirectional cropping parameter γ, wherein the general value range of the bidirectional cropping parameter γ is [0.12, 0.15], and the preferred embodiment of γ is 0.14.

[0088] In implementation, the method of the present invention determines the consistency between the edge and the internal texture structure by setting a preset length. Since the stronger the consistency between the cutting position and the internal texture structure of the air film after cutting, the more internal parts will be affected after the edge is cut. If there is inconsistency, the air film at the cutting position will be more susceptible to damage during cutting, resulting in edge breakage and deformation, which will have a negative impact on the subsequent heat sealing and seam quality. By measuring the edge of the air film after cutting, comparing it with the preset length, and adjusting the cutting parameters, a quantitative assessment of the degree of damage to the air film edge is achieved.

[0089] Specifically, in step S2, adjusting the cutting speed includes:

[0090] If the consistency of the test air film does not meet the requirements and the test air film does not have a bidirectional cutting condition, obtaining a minimum value of the vibration intensity of the test air film during the one test cutting;

[0091] Adjusting the cutting speed of the test air film that does not meet the bidirectional cutting condition to the cutting speed when the vibration intensity is the minimum value;

[0092] The condition that the test air film does not have bidirectional cutting is that the cutting length of the test air film is less than a preset cutting length.

[0093] Specifically, an infrared sensor is provided above the cutting blade of the automatic cutting machine to detect the vibration intensity of the air film.

[0094] Specifically, the general value range of the preset cutting length is [0.46m, 0.68m], and the preferred embodiment of the preset cutting length is 0.5m.

[0095] In implementation, the method of the present invention adopts two-way cutting for the air membrane whose consistency does not meet the requirements and has the conditions for two-way cutting, so as to avoid the stress generated in one direction from causing damage to the internal structure, and effectively disperses the stress generated in the cutting process, thereby achieving the improvement of the stability of the overall structure of the air membrane after cutting; by adjusting the cutting speed of the air membrane whose consistency does not meet the requirements and does not have the conditions for two-way cutting to the cutting speed at the minimum value of the vibration intensity, the minimum damage to the air membrane during the cutting process is achieved, the risk of cracking and damage of the air membrane due to excessive cutting stress is reduced, and the integrity of the air membrane is ensured. At the same time, it can also improve the flatness of the edge of the air membrane after cutting, reduce the difficulty of subsequent heat sealing and seaming, and further achieve the improvement of the stability and bearing capacity of the membrane structure.

[0096] Specifically, in step S3, adjusting the number of cropping layers includes:

[0097] Obtaining the number of the edge damaged sections;

[0098] comparing the number of the edge damaged sections with a preset number;

[0099] If the number of the edge damaged sections is greater than the preset number, it is determined that the shear stress of the test air film does not meet the requirement, and the number of shear layers is increased.

[0100] Specifically, the number of cutting layers is positively correlated with the number of the edge damaged sections.

[0101] Specifically, the general value range of the preset number is [12, 20], and the preferred embodiment of the preset number is 18.

[0102] During implementation, the method of the present invention determines the shear stress of the air film by setting a preset number. Since the internal stress distribution of the air film during the cutting process is uneven, the stress is discontinuous, which leads to an increase in the number of damaged edge sections. The discontinuous stress causes stress concentration at the cutting edge or seam of the air film, increasing the risk of cracking and damage of the air film, thereby affecting the bearing capacity of the membrane structure. During the long-term use of the membrane structure, the air film will gradually deform and relax, affecting the stability of the membrane structure. By analyzing the shear stress of the air film, the bearing capacity of the air film is improved.

[0103] During implementation, the number of cutting layers of the second test air mold increases by 1 every time the difference between the number of edge damaged segments and the preset number exceeds 1. For example, if the difference between the number of edge damaged segments and the preset number is 3, and the current number of cutting layers of the second test air mold is 4, the number of cutting layers of the second test air mold increases to 2 layers + 1 layer × 3 = 5 layers.

[0104] In practice, the method described herein increases the number of cutting layers for air films that do not meet required consistency or shear stress requirements. Because air films lack continuous stress, this stress is suppressed by adding more layers, thereby reducing the risk of cracking and damage. Increasing the number of cutting layers also enhances the strength and toughness of the air film, improves its sealing properties, and reduces air leakage, ultimately improving the effectiveness of environmentally friendly air films used in foundation pit construction.

[0105] Specifically, in step S3, adjusting the cropping angle includes:

[0106] If the number of the edge damaged sections is less than or equal to the preset number, it is determined that the shear stress of the test air film meets the requirements, and the shear angle is reduced.

[0107] The cutting angle is the angle between the main back surface of the cutting knife and the surface of the air film; and the cutting angle is negatively correlated with the edge damaged length.

[0108] In implementation, if the difference between the damaged edge length and the preset length is within 0.01m, the cutting angle is reduced by 1.2°. If the difference between the damaged edge length and the preset length exceeds 0.01m, the cutting angle is reduced by 1° for every 0.01m. For example, if the difference between the damaged edge length and the preset length is 0.03m and the current cutting angle is 86°, the cutting angle is reduced to 86°-1.2°-1°-1°=82.4°.

[0109] In implementation, the method of the present invention reduces the cutting angle of the air film whose consistency does not meet the requirements but whose cutting stress meets the requirements, so as to change the direction of the stress line and reduce the concentration of stress. It can also make the edge of the air film smoother after cutting, reduce the difficulty of subsequent processing, and achieve improved production efficiency.

[0110] Specifically, in step S5, adjusting the number of seams includes:

[0111] Obtaining the density of damaged positions within a unit edge damaged length of the test air film;

[0112] If the density is greater than a preset density, the area within the unit edge damaged length is determined to be a high stress area;

[0113] If the density is less than or equal to the preset density, the area within the unit edge damaged length is determined to be a low stress area;

[0114] The number of seams at the edge of the air film corresponding to the high stress area is reduced.

[0115] The number of seams is negatively correlated with the density.

[0116] Specifically, the general value of the preset density is [5 pieces / meter, 8 pieces / meter], and the preferred embodiment of the preset density is 6 pieces / meter.

[0117] In implementation, the number of seams is reduced by 2 for every time the difference between the density and the preset density exceeds 1 / m. For example, if the difference between the density and the preset density is 2 / m, and the number of seams at the edge of the air film corresponding to the current high stress area is 25, the number of seams is reduced to 25-2×2=21.

[0118] Specifically, the number of seams is the number of partitions between the independently inflatable partitions of the temporal part of the air membrane; the number of seams is adjusted by a multi-air-path linkage control device, which includes several pneumatic valves; when the number of seams is reduced, the multi-air-path linkage control device reduces the number of pneumatic valves that are opened.

[0119] During implementation, the method of the present invention reduces the number of seams at the edge of the air film corresponding to the high stress area to reduce stress concentration at the seams, making the air film more uniform when subjected to force, and improving the strength and stability of the seams. The reduction in the number of seams can also reduce the risk of air leakage at the seams, further improving the sealing performance and bearing capacity of the membrane structure, avoiding the decrease in air film strength and damage due to continuous seams at stress positions, and achieving improved stability of the environmentally friendly air film used for foundation pit construction.

[0120] Specifically, the time interval between heat sealing and cooling is determined based on the difference in air film expansion speed between the high stress area and the low stress area in the heat seal, including:

[0121] respectively obtaining the average expansion speed of the air film in the high stress area and the low stress area during the heat sealing process, and calculating the difference in the expansion speed of the air film;

[0122] If the difference is greater than a preset difference, it is determined that the degree of fusion does not meet the requirements, and the time interval between the heat sealing and cooling is increased.

[0123] Specifically, the time interval is positively correlated with the difference amount.

[0124] Specifically, the difference in the expansion speed of the air film is the difference between the average expansion speed of the air film in the low stress area during heat sealing and the average expansion speed of the air film in the high stress area during heat sealing.

[0125] Specifically, the collision velocity is the change in the thickness of the air film per unit time.

[0126] Specifically, the expansion speed is detected by an infrared sensor provided on the inner wall of the high-frequency heat sealing machine above the heat sealing plate.

[0127] Specifically, the general value range of the preset difference amount is [0.034 mm / s, 0.04 mm / s], and the preferred embodiment of the preset difference amount is 0.036 mm / s.

[0128] During implementation, when the difference between the difference amount and the preset difference amount is within 0.001mm / s, the time interval between heat sealing and cooling is increased by 10s. When the difference between the difference amount and the preset difference amount exceeds 0.001mm / s, the time interval is increased by 14s for every 0.001mm / s. For example, if the difference between the difference amount and the preset difference amount is 0.003mm / s and the current time interval is 300s, the time interval is increased to 300s+10+14s=324s.

[0129] In implementation, the method of the present invention sets a preset difference amount. When it is determined that the degree of fusion does not meet the requirements, the time interval between heat sealing and cooling is increased to reduce the structural mutation caused by the small time interval, which may cause the high stress area to be damaged again, thereby improving the strength and sealing performance of the air film.

[0130] The present invention also provides an embodiment of an environmentally friendly air film for foundation pit construction, wherein the components of the environmentally friendly air film include: a PVDF coating as a self-cleaning layer, a PVC coating, an adhesive layer, and a substrate.

[0131] The order of the constituent materials of each layer of the environmentally friendly air film from top to bottom is PVDF coating-PVC coating-adhesive layer-base material-adhesive layer-PVC coating-PVDF coating;

[0132] An anti-UV layer is further provided between the PVDF coating and the adjacent PVC coating.

[0133] Specifically, examples of the components of the substrate include polyester fiber and glass fiber; examples of the components of the adhesive layer include polyurethane resin adhesive and solvent-based polyurethane adhesive; and the component of the UV-resistant layer is titanium dioxide.

[0134] Specifically, the general value range of the thickness of the substrate is [0.8mm, 1.2mm], and the preferred embodiment of the thickness of the substrate is 1.0mm; the general value range of the thickness of the adhesive layer is [0.01mm, 0.03mm], and the preferred embodiment of the thickness of the adhesive layer is 0.02mm; the general value range of the thickness of the PVC coating is [0.03mm, 0.036mm], and the preferred embodiment of the thickness of the PVC coating is 0.032mm; the general value range of the thickness of the PVDF coating is [0.03mm, 0.036mm], and the preferred embodiment of the thickness of the PVDF coating is 0.032mm; the general value range of the thickness of the anti-UV layer is [0.01mm, 0.03mm], and the preferred embodiment of the thickness of the PVDF coating is 0.014mm.

[0135] Specifically, the parameters of the environmentally friendly air film include: gram weight ≥1300±50g, tensile strength ≥7000N, tear strength ≥700N, thickness ≥1mm, and combustion performance level B1.

[0136] During implementation, the method of the present invention sets the materials of the environmentally friendly air film as PVDF coating, PVC coating, adhesive layer, and substrate, and there is an anti-UV layer between the self-cleaning layer on the surface and the PVC layer. This layer of material mainly blocks the damage of ultraviolet rays to PVC and prevents the breakage of the PVC molecular structure. The material without PVDF will turn yellow and easily accumulate dust after a period of use. The addition of PVDF can improve the self-cleaning ability, and the PVC coating increases the good waterproof and moisture-proof properties of the air film, ensuring the dryness of the internal environment of the foundation pit. The setting of the adhesive layer makes the layers of materials tightly combined, avoids the phenomenon of interlayer peeling, and realizes the improvement of the stability of the air film.

[0137] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A method for preparing an environmentally friendly air film for foundation pit construction, characterized in that: include: Step S1, performing a test cutting on the air film to obtain a test air film; Step S2, determining the air film cutting method according to the damaged length of the edge of the test air film, including adjusting the cutting method from unidirectional cutting to bidirectional cutting, Alternatively, the cutting speed is adjusted according to the vibration intensity of the test air film; Step S3, determining a cutting parameter adjustment method according to the damaged edge length and the number of damaged edge sections, including adjusting the number of cutting layers or adjusting the cutting angle; Step S4, performing a secondary test cutting on the test air film according to the air film cutting processing method and the cutting parameter adjustment method; Step S5: If the edge damaged length meets the requirement and the number of edge damaged sections does not meet the requirement, the number of seams is adjusted and step S6 is executed after the number of seams is adjusted. If the edge damaged length does not meet the requirement, steps S1-S4 are repeated until the edge damaged length of the air film meets the requirement. Step S6, actually cutting the air film according to the air film cutting processing method and the cutting parameter adjustment method to output air film slices; Step S7, performing heat merging and cooling on the air film slices according to the execution result of step S5 to obtain a finished air film; The time interval between heat sealing and cooling is determined according to the difference in expansion speed of the air film between the high stress area and the low stress area in the heat sealing.

2. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 1, characterized in that: In step S2, adjusting the cutting mode from unidirectional cutting to bidirectional cutting includes: Performing image analysis on the test air film to obtain the damaged length of the edge; comparing the damaged length of the edge with a preset length; If the damaged length of the edge is greater than the preset length, it is determined that the consistency between the edge and the internal texture structure of the test air membrane does not meet the requirements, and a bidirectional cutting method is adopted; The edge damaged length is the sum of the lengths of the edges that are damaged or deformed.

3. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 2, characterized in that: In step S2, adjusting the cutting speed includes: If the consistency of the test air film does not meet the requirements and the test air film does not have a bidirectional cutting condition, obtaining a minimum value of the vibration intensity of the test air film during the one test cutting; Adjusting the cutting speed of the test air film that does not meet the bidirectional cutting condition to the cutting speed when the vibration intensity is the minimum value; The condition that the test air film does not have bidirectional cutting is that the cutting length of the test air film is less than a preset cutting length.

4. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 3, characterized in that: In step S3, adjusting the number of cropping layers includes: Obtaining the number of the edge damaged sections; comparing the number of the edge damaged sections with a preset number; If the number of the edge damaged sections is greater than the preset number, it is determined that the shear stress of the test air film does not meet the requirement, and the number of shear layers is increased.

5. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 4, characterized in that: The number of cutting layers is positively correlated with the number of damaged edge sections.

6. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 5, characterized in that: In step S3, adjusting the cropping angle includes: If the number of the edge damaged sections is less than or equal to the preset number, it is determined that the shear stress of the test air film meets the requirements, and the shear angle is reduced. The cutting angle is the angle between the main back surface of the cutting knife and the surface of the air film; and the cutting angle is negatively correlated with the edge damaged length.

7. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 6, characterized in that: In step S5, adjusting the number of seams includes: Obtaining the density of damaged positions within a unit edge damaged length of the test air film; If the density is greater than a preset density, the area within the unit edge damaged length is determined to be a high stress area; If the density is less than or equal to the preset density, the area within the unit edge damaged length is determined to be a low stress area; The number of seams at the edge of the air film corresponding to the high stress area is reduced. The number of seams is negatively correlated with the density.

8. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 7, characterized in that: The time interval between heat sealing and cooling is determined according to the difference in expansion speed of the air film between the high stress area and the low stress area in the heat sealing, including: respectively obtaining average expansion speeds of the air films in the high stress area and the low stress area during heat sealing, and calculating a difference in the expansion speeds of the air films; If the difference is greater than a preset difference, it is determined that the degree of fusion does not meet the requirements, and the time interval between the heat sealing and cooling is increased.

9. The method for preparing an environmentally friendly air film for foundation pit construction according to claim 8, characterized in that: The time interval between heat sealing and cooling is positively correlated with the difference.

10. An environmentally friendly air film prepared by the method for preparing an environmentally friendly air film for foundation pit construction according to any one of claims 1 to 9, characterized in that: The components of the environmentally friendly air film include: PVDF coating as a self-cleaning layer, PVC coating, adhesive layer, and substrate. The order of the constituent materials of each layer of the environmentally friendly air film from top to bottom is PVDF coating-PVC coating-adhesive layer-base material-adhesive layer-PVC coating-PVDF coating; An anti-UV layer is further provided between the PVDF coating and the adjacent PVC coating.

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