Method for manufacturing geocomposite

Abstract

The application discloses a preparation method of composite geotextile, and belongs to the technical field of geotextile processing, which solves the problems of insufficient interlayer bonding strength, poor permeation stability and inability to adapt to regional differentiated mechanical requirements in traditional processes. The method selects two layers of synthetic fiber geotextile and one layer of high molecular geotextile film, and adopts a double-station gradient needling process by using a gradient needling machine: coarse needle needling is first carried out on the upper and lower sides simultaneously to pre-reinforce to a film thickness of 50-60% depth, and then fine needle needling is carried out to finish to a depth of 70-80%, the needling density is preset to 20-70 needles / cm2 according to different stress areas of the film material, the needling depth, density and film material tension data are collected in real time through a dynamic monitoring system during the process, and the parameters are automatically adjusted, and finally, a stable structure is formed through heat setting treatment at 120-140 DEG C for 8-12 minutes. The composite geotextile prepared by the method has high-strength bonding interface and excellent impermeability, and is suitable for engineering fields such as water conservancy engineering impermeability, road base reinforcement and landfill isolation.

Description

Technical Field

[0001] This invention relates to the field of geotextile processing technology. More specifically, this invention relates to a method for preparing composite geotextiles. Background Technology

[0002] In the field of civil engineering, composite geotextiles are widely used in seepage prevention, isolation, and reinforcement projects. Traditional composite geotextiles often employ single-layer needle punching or hot-pressing composite processes, but these suffer from insufficient interlayer bonding and poor permeability stability. Especially in hydraulic engineering, due to long-term exposure to water pressure and soil stress, existing products frequently exhibit delamination between the polymer membrane and the fabric, leading to a sharp decline in seepage prevention performance. Analysis reveals that traditional needle punching processes, using unidirectional, single-pass needle punching, cannot form an effective three-dimensional bond structure. The limited setting of needle punching depth and density fails to adapt to varying stress distributions in different areas, causing premature failure in weak areas. Furthermore, the coarse control of parameters in the heat setting process leads to uneven temperature distribution, easily causing material shrinkage and deformation, affecting the dimensional stability of the final product. Existing technologies attempt to improve performance by increasing needle punching density or using multi-layer composite structures, but excessive needle punching can disrupt the continuity of the polymer membrane, thus reducing seepage prevention effectiveness. How to achieve high-strength bonding while ensuring the integrity of the polymer membrane, while simultaneously meeting the mechanical performance requirements of different areas, has become a pressing technical challenge. During the production process, due to the complex nonlinear relationship between the needle punching process parameters and the finished product performance, traditional empirical parameter setting methods are difficult to achieve precise control, resulting in a product qualification rate of less than 70%. Existing dynamic monitoring systems mostly use a single sensor for offline detection, which cannot provide real-time feedback for adjusting process parameters, seriously affecting production efficiency and product consistency. Summary of the Invention

[0003] One objective of this invention is to provide a method for preparing composite geotextiles, which solves the problem that the traditional needle-punching process in the preparation of composite geotextiles is too simple, resulting in insufficient interlayer bonding strength and poor permeability stability, and thus failing to meet the differentiated mechanical performance requirements of different engineering areas.

[0004] To achieve these objectives and other advantages of the present invention, according to one aspect of the present invention, a method for preparing a composite geotextile is provided, comprising the following steps: Step 1: Select two layers with a unit area mass of 100~300 g / m². 2 Synthetic fiber geotextiles with a tensile strength greater than 15 kN / m, and geotextiles with a thickness of 0.5~3.0 mm and a permeability coefficient less than 1×10⁻⁶. -13 High-molecular geomembrane with a flow rate of cm / s; Step 2: Two layers of synthetic fiber geotextile are stacked on the upper and lower surfaces of the polymer geomembrane, and then sent to a gradient needle punching machine. A dual-station gradient needle punching process is used to pre-reinforce the geomembrane with coarse needles from both the upper and lower sides at a depth of 50-60% of the thickness of the polymer geomembrane. Then, fine needles are used to finish the geomembrane from both the upper and lower sides at a depth of 70-80% of the thickness of the polymer geomembrane. The needle punching density is preset according to the stress requirements of different areas of the polymer geomembrane. During the needle punching process, the needle punching parameters are adjusted in real time through a dynamic monitoring system. Step 3: Heat set the needle-punched geotextile. The heat setting temperature is controlled at 120~140℃ for 8~12 minutes. Then, the surface of the heat-set geotextile is treated to finally obtain the composite geotextile.

[0005] Preferably, the synthetic fiber geotextile is made of polyester fiber, and the polymer geomembrane is made of high-density polyethylene.

[0006] Preferably, in step two, the preset value for the needle puncture density is: The polymer geomembrane is divided into a core stress-bearing zone, an edge reinforcement zone, a weak and sensitive zone, and a conventional zone; among which... The preset needle density in the core stress zone is 35-45 needles / cm². 2 Orthogonal cross needle puncture path is adopted; The preset needle density in the edge reinforcement zone is 50-60 needles / cm. 2 It adopts a spiral progressive needle puncture path; The preset needle density for the weak and sensitive area is 60-70 needles / cm². 2 A ring-shaped encrypted needle penetration path is adopted; The conventional area refers to the main body excluding the special areas mentioned above, accounting for 60-70% of the total area of ​​the polymer geomembrane, with a preset needle-punching density of 20-30 needles / cm. 2 A uniform parallel needle puncture path is used.

[0007] Preferably, the needle spacing of the orthogonal cross needle puncture path is 5-8 mm and the angle is 90°; the needle spacing of the spiral progressive needle puncture path is 3-5 mm and the spiral radius increases progressively; the ring radius of the annular densified needle puncture path is 1-2 mm; and the needle spacing of the uniform parallel needle puncture path is 10-15 mm.

[0008] Preferably, the dynamic monitoring system includes a displacement sensor installed on the side of the needle seat of the needle punching machine for real-time monitoring of the needle punching depth, an industrial camera installed directly above the needle punching machine for detecting the distribution density of needle punch points using an image recognition algorithm, and a tension sensor installed at both ends of the polymer geomembrane conveying roller for real-time monitoring of the membrane tension.

[0009] Preferably, the dynamic monitoring system collects the needle penetration depth, needle penetration density, and polymer geomembrane tension in real time, and periodically samples and tests the composite geotextile to obtain its tensile strength, permeability coefficient, and peel strength. These data, along with the collected needle penetration depth, needle penetration density, and polymer geomembrane tension, are processed through an industrial internet platform for data normalization to establish a prediction model based on a BP neural network. The training sample size of the prediction model is ≥1000 groups, and R0... 2 ≥0.95, the system predicts the quality of composite geotextile by analyzing the results of the model in real time. When the prediction results exceed the preset control range, the system automatically adjusts the needle punching parameters.

[0010] Preferably, the method for adjusting the acupuncture parameters is as follows: Needle depth adjustment: Based on the deviation between the predicted result and the control range, the depth is adjusted in increments of 0.02 mm, with a maximum adjustment range of ±0.2 mm and an adjustment cycle of 3 min. If the predicted fracture strength is lower than the control limit, the needle depth is increased by 0.02 mm; if the predicted permeability coefficient is lower than the control limit, the needle depth is decreased by 0.02 mm. Needle density adjustment: The needle density is changed by adjusting the motor speed of the needle punching machine through a frequency converter. The adjustment range is ±15% based on the reference speed. If the predicted fracture strength or peel strength is lower than the control limit, the operating speed of the needle punching machine is increased by 10%. If the predicted penetration coefficient is lower than the control limit, the operating speed of the needle punching machine is decreased by 10%. Adjustment of polymer geomembrane tension: Adjustment is made according to the deviation between the predicted results and the control range. If the predicted peel strength is lower than the control limit, the tension of the polymer geomembrane is increased by 5 N. If the predicted permeability coefficient is lower than the control limit, the tension of the polymer geomembrane is decreased by 3 N.

[0011] Preferably, the method for adjusting the acupuncture parameters has a priority mechanism, specifically: setting a lower and upper limit for the control of the permeability coefficient, a lower limit for the control of the fracture strength, and a lower limit for the control of the peel strength; when the predicted permeability coefficient is less than the lower limit or greater than the upper limit, the predicted fracture strength is less than the lower limit, or the predicted peel strength is less than the lower limit, the corresponding indicators are determined to be abnormal respectively. When multiple anomalies occur simultaneously, parameter adjustments are performed in the order of priority: permeability coefficient anomaly > fracture strength anomaly > peel strength anomaly. If the permeability coefficient is abnormal, adjust the acupuncture parameters in the order of polymer geomembrane tension, acupuncture depth, and acupuncture density. If the permeability coefficient is normal but the tensile strength is abnormal, adjust the acupuncture parameters in the order of acupuncture depth, acupuncture density, and polymer geomembrane tension. If the permeability coefficient and tensile strength are also normal but the peel strength is abnormal, adjust the acupuncture parameters in the order of polymer geomembrane tension, acupuncture density, and acupuncture depth.

[0012] Preferably, the method for adjusting the acupuncture parameters has an anti-conflict mechanism, specifically: The conflict between predefined increases in needle penetration depth and decreases in needle penetration density, the conflict between increases in needle penetration density and decreases in polymer geomembrane tension, and the conflict between increases in needle penetration depth and increases in polymer geomembrane tension. When there is a conflict between increasing acupuncture depth and decreasing acupuncture density, the acupuncture depth adjustment should be performed first. When there is a conflict between increased needle density and decreased tension of polymer geomembrane, the adjustment of polymer geomembrane tension should be prioritized. When there is a conflict between increasing needle penetration depth and increasing polymer geomembrane tension, if the permeability coefficient is abnormal, the needle penetration depth should be adjusted first; if the permeability coefficient is not abnormal, the polymer geomembrane tension should be adjusted first.

[0013] This invention offers at least the following advantages: It utilizes a gradient needle-punching process to control the needle-punching depth in stages. Coarse needles pre-reinforce the basic bonding structure, while fine needles refine and strengthen the interface bonding, achieving a bonding depth of 80% of the film thickness to ensure a three-dimensional interlocking effect. Precisely preset needle-punching densities in different zones achieve differentiated enhancement; a medium density in the core area maintains film integrity, while a high density in the edge area enhances tear resistance. Precise control of heat-setting temperature and time ensures the orderly arrangement of polymer chain segments, eliminating internal stress and effectively improving product dimensional stability. A dynamic monitoring system adjusts process parameters in real time, effectively improving the product yield.

[0014] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0015] The present invention will now be described in further detail with reference to specific embodiments, so that those skilled in the art can implement it based on the description.

[0016] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0017] It should be noted that, unless otherwise specified, the experimental methods described in the following implementation plan are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified.

[0018] This invention provides a method for preparing a composite geotextile, comprising the following steps: Step 1: Select two layers with a unit area mass of 100~300 g / m². 2 Synthetic fiber geotextiles with a tensile strength greater than 15 kN / m, and geotextiles with a thickness of 0.5~3.0 mm and a permeability coefficient less than 1×10⁻⁶. -13 High-molecular geomembrane with a flow rate of cm / s; Step 2: Two layers of synthetic fiber geotextile are stacked on the upper and lower surfaces of the polymer geomembrane, and then sent to a gradient needle punching machine. A dual-station gradient needle punching process is used to pre-reinforce the geomembrane with coarse needles from both the upper and lower sides at a depth of 50-60% of the thickness of the polymer geomembrane. Then, fine needles are used to finish the geomembrane from both the upper and lower sides at a depth of 70-80% of the thickness of the polymer geomembrane. The needle punching density is preset according to the stress requirements of different areas of the polymer geomembrane. During the needle punching process, the needle punching parameters are adjusted in real time through a dynamic monitoring system. Step 3: Heat set the needle-punched geotextile. The heat setting temperature is controlled at 120~140℃ for 8~12 minutes. Then, the surface of the heat-set geotextile is treated to finally obtain the composite geotextile.

[0019] In the lamination process of this technical solution, the bonding of geotextile and geomembrane can be completed by an automatic layup machine. The vacuum adsorption platform equipped with this machine ensures the smoothness of the interlayer adhesion, with the adsorption pressure controlled between -0.05 and -0.08 MPa. The layup speed is set to 2 m / min, and the laminated material is conveyed to the needle punching process via conveyor rollers. The gradient needle punching machine in step two can be a double-sided needle punching machine, equipped with two sizes of needles: 9×25 mm and 15×40 mm. For coarse needle punching, the 15×40 mm needle group is selected; for fine needle punching, the 9×25 mm needle group is switched. The needle punching frequency is set to 600 times / min in the pre-reinforcement stage and increased to 800 times / min in the finishing stage. A conical needle tip (60° apex angle) is used to reduce penetration resistance and prevent membrane tearing. The needle punching machine parameter adjustment cycle can be extended to 10 seconds, synchronized with the mechanical response time (e.g., servo motor acceleration time of 5 seconds).

[0020] In another technical solution, the synthetic fiber geotextile is made of polyester fiber, and the polymer geomembrane is made of high-density polyethylene.

[0021] In another technical solution, the preset value for the needle puncture density in step two is: The polymer geomembrane is divided into a core stress-bearing zone, an edge reinforcement zone, a weak and sensitive zone, and a conventional zone; among which... The preset needle density in the core stress zone is 35-45 needles / cm². 2 Orthogonal cross needle puncture path is adopted; The preset needle density in the edge reinforcement zone is 50-60 needles / cm. 2 It adopts a spiral progressive needle puncture path; The preset needle density for the weak and sensitive area is 60-70 needles / cm². 2 A ring-shaped encrypted needle penetration path is adopted; The conventional area refers to the main part excluding the special areas mentioned above, accounting for 60-70% of the total area of ​​the polymer geomembrane. The preset needle density is 20-30 needles / cm², and a uniform parallel needle path is used.

[0022] In this technical solution, a zoned differentiated needle-punching process is adopted to divide the polymer geomembrane into four functional zones for targeted treatment. Zone division can be achieved by pre-marking zoning lines on the surface of the polymer geomembrane using a Shanghai Hugong HG-MK30 laser marking machine. The core stress-bearing zone, located in the middle of the membrane material and accounting for 20% of the total area, employs an orthogonal cross-needling path, with needles alternately piercing in two mutually perpendicular directions to form a grid-like structure. The needle-punching density is controlled at 35-45 needles / cm². 2 Within this range, the uniformity of intensity in the longitudinal and latitudinal directions is significantly improved. The edge reinforcement zone is located within 5cm of the outer edge of the membrane material, employing a spiral progressive needling path. The needles gradually penetrate from the outside to the inside along an Archimedean spiral trajectory, increasing the needling density to 50-60 needles / cm. 2 This effectively enhances edge anti-peeling performance. An infrared thermal imager is used to automatically detect weld defects and pre-determine defect points. A 15mm radius annular area is set around the pre-determined defect points in the weak and sensitive area. A ring-shaped, densely packed needle-punching path is used, with multiple concentric circles puncturing around the defect points, achieving a needle-punching density of 60-70 needles / cm. 2 This targeted approach improves the performance of weak points such as weld joints. The remaining 60-70% area is a standard region, where uniform parallel needle-punching paths are used, with a needle-punching density controlled at 20-30 needles / cm². 2To ensure overall structural stability, the region division is achieved through a laser projection positioning system. This system projects different colored light spots onto the membrane surface to mark the boundaries of each region, with positioning accuracy controlled within ±0.5mm. The needle-punching path is driven by a servo motor, moving the needle-punching machine beam along a preset trajectory. The repeatability of the movement and positioning accuracy reaches ±0.1mm, ensuring precise execution of complex paths. Weak and sensitive areas are identified using an infrared thermal imager to detect abnormal temperature points on the membrane surface, automatically delineating the areas requiring reinforcement. Needling parameters for different regions are switched in real-time by a PLC control system, ensuring coordinated operation of multiple process parameters. After zoning, the longitudinal and latitudinal fracture strength ratio of the core stress area is significantly improved, and the structural symmetry is significantly enhanced. The peel strength of the edge reinforcement area is improved compared to the homogeneous area, effectively preventing edge delamination. Weak and sensitive areas are reinforced with ring-shaped densified punctures, significantly reducing the fluctuation range of the permeability coefficient around defect points and significantly lowering the risk of leakage.

[0023] In another technical solution, the needle spacing of the orthogonal cross needle puncture path is 5~8 mm and the angle is 90°; the needle spacing of the spiral progressive needle puncture path is 3~5 mm and the spiral radius increases progressively; the ring radius of the annular densified needle puncture path is 1~2 mm; and the needle spacing of the uniform parallel needle puncture path is 10~15 mm.

[0024] In another technical solution, the dynamic monitoring system includes a displacement sensor installed on the side of the needle seat of the needle punching machine for real-time monitoring of the needle punching depth, an industrial camera installed directly above the needle punching machine for detecting the distribution density of needle punching points using an image recognition algorithm, and a tension sensor installed at both ends of the polymer geomembrane conveying roller for real-time monitoring of the membrane tension.

[0025] In this technical solution, the dynamic monitoring system includes a laser displacement sensor installed on the side of the needle holder of the needle-punching machine. Its measurement accuracy is ±0.01 mm, and the sampling frequency is 1000 Hz, monitoring the deviation between the actual needle displacement and the set value in real time. An industrial camera uses a 5-megapixel CMOS sensor with a ring LED light source to capture images of the needle points at 30 frames per second. The needle density distribution is calculated using image processing algorithms. A strain gauge tension sensor is installed at both ends of the film conveying roller, with a range of 0-200 N and a resolution of 0.1 N, monitoring changes in film conveying tension in real time. The laser displacement sensor is installed on the side of the needle holder at a 45° angle to avoid oil interference, achieving real-time needle displacement monitoring with an accuracy of ±0.01 mm. The industrial camera accurately calculates the needle density distribution using morphological opening operations and Hough transform algorithms. The data acquisition module transmits the sensor signals to the PLC controller, which uses a built-in fuzzy PID algorithm to achieve multi-parameter coordinated control. The needle punching stroke is adjusted by driving a servo motor, thereby adjusting the needle punching depth; the operating speed is changed by adjusting the frequency converter of the needle punching machine spindle, thereby changing the needle punching density; and the film tension is changed by controlling the output torque of the unwinding magnetic powder brake.

[0026] In another technical solution, the dynamic monitoring system collects the needle penetration depth, needle penetration density, and polymer geomembrane tension in real time, and periodically samples and tests the composite geotextile to obtain its tensile strength, permeability coefficient, and peel strength. These data, along with the collected needle penetration depth, needle penetration density, and polymer geomembrane tension, are processed through an industrial internet platform for data normalization to establish a prediction model based on a BP neural network. The training sample size of the prediction model is ≥1000 groups, and R² ≥ 0.95. The system predicts the quality of the composite geotextile by analyzing the model output results in real time. When the prediction results exceed the preset control range, the system automatically adjusts the needle penetration parameters.

[0027] In this technical solution, an industrial internet-based dynamic monitoring system is used to achieve intelligent control and quality prediction of the composite geotextile production process. The system uploads real-time data from displacement sensors, industrial cameras, and tension sensors to the industrial internet platform via the Modbus protocol, forming a digital twin model of the production process. Data normalization processing includes: scaling the original voltage signal of the needle penetration depth to a range of 0.1-1.0 mm to ensure comparability of data with different dimensions; counting the number of pinholes per unit area after grayscale and binarization of the needle penetration density image; and using a moving average filter with a window width of 50 sampling points to effectively eliminate high-frequency noise interference for the membrane tension data. The BP neural network prediction model adopts a three-layer architecture. During model construction, the training data includes 1200 sets of production samples. The input layer contains three parameters: needle penetration depth, needle penetration density, and membrane tension, with normalized values ​​ranging from [0,1]. The hidden layer has 8 neurons, and the activation function is ReLU. The output layer corresponds to three quality indicators: tensile strength, permeability coefficient, and peel strength. The model was trained based on 1200 sets of historical production data, using the Levenberg-Marquardt algorithm to optimize weight parameters with a learning rate of 0.01, trained until the mean squared error was less than 0.005. During online prediction, the model outputs a quality prediction value every 5 seconds. When the permeability coefficient or fracture strength falls within the preset control range, the system automatically triggers parameter adjustment commands. The system maps the raw data to a standard interval using a data normalization formula to ensure model input stability. The neural network employs a dynamic update mechanism, retraining the model after every 200 sets of new production data to maintain the prediction accuracy R. 2 The value is greater than 0.93. This prediction system enables quality inspection to have a short response time, high efficiency, and small error, reducing the frequency of quality sampling and saving inspection costs in practical applications.

[0028] In another technical solution, the method for adjusting the acupuncture parameters is as follows: Needle depth adjustment: Based on the deviation between the predicted result and the control range, the depth is adjusted in increments of 0.02 mm, with a maximum adjustment range of ±0.2 mm and an adjustment cycle of 3 min. If the predicted fracture strength is lower than the control limit, the needle depth is increased by 0.02 mm; if the predicted permeability coefficient is lower than the control limit, the needle depth is decreased by 0.02 mm. Needle density adjustment: The needle density is changed by adjusting the motor speed of the needle punching machine through a frequency converter. The adjustment range is ±15% based on the reference speed. If the predicted fracture strength or peel strength is lower than the control limit, the operating speed of the needle punching machine is increased by 10%. If the predicted penetration coefficient is lower than the control limit, the operating speed of the needle punching machine is decreased by 10%. Adjustment of polymer geomembrane tension: Adjustment is made according to the deviation between the predicted results and the control range. If the predicted peel strength is lower than the control limit, the tension of the polymer geomembrane is increased by 5 N. If the predicted permeability coefficient is lower than the control limit, the tension of the polymer geomembrane is decreased by 3 N.

[0029] In this technical solution, the needle penetration depth adjustment adopts a closed-loop control strategy. When the predicted fracture strength is lower than 15 kN / m, the servo motor drives the needle guide rail to move downward in steps of 0.02 mm / time, with a maximum cumulative adjustment of +0.2 mm; if the predicted penetration coefficient is lower than 5×10 -14 If the needle density is set to cm / s, the reverse adjustment will shift upwards by 0.02 mm per cycle, with a lower limit of -0.2 mm. Needle density adjustment is achieved by changing the spindle motor speed via a frequency converter; a base speed of 1500 rpm corresponds to a density of 30 needles / cm². 2 For every 100 rpm increase or decrease in rotation speed, the density changes by ±2 needles / cm. 2 The membrane tension adjustment uses a PID controller to regulate the magnetic powder brake current, with a current-to-tension conversion coefficient of 0.5 N / mA. When an increase of 5 N in tension is required, the current is increased by 10 mA. The system is set to an adjustment cycle of 180 seconds, with a 30-second stabilization period after each adjustment before collecting new data. Needle penetration depth calibration uses standard gauge blocks to calibrate the zero point of the displacement sensor daily, compensating for mechanical wear errors. The inverter acceleration / deceleration time is set to 10 seconds to avoid sudden speed changes that could cause needle breakage. The tension closed-loop control parameters are a proportional coefficient Kp = 2.5, an integral time Ti = 5 s, and a derivative time Td = 0.5 s, ensuring a balance between response speed and stability. Needle penetration depth adjustment reduces the fracture strength fluctuation range from ±1.8 kN / m to ±0.5 kN / m. The frequency conversion speed regulation accuracy reaches ±1 rpm, and the needle penetration density control error is < ±1 needle / cm. 2 Tension adjustment response time < 2 seconds, overshoot < 3%. This control strategy can significantly improve product performance consistency.

[0030] In another technical solution, the method for adjusting the acupuncture parameters has a priority mechanism, specifically: setting a lower and upper limit for the control of the permeability coefficient, a lower limit for the control of the fracture strength, and a lower limit for the control of the peel strength; when the predicted permeability coefficient is less than the lower limit or greater than the upper limit, the predicted fracture strength is less than the lower limit, or the predicted peel strength is less than the lower limit, the corresponding indicators are determined to be abnormal respectively. When multiple anomalies occur simultaneously, parameter adjustments are performed in the order of priority: permeability coefficient anomaly > fracture strength anomaly > peel strength anomaly. If the permeability coefficient is abnormal, adjust the acupuncture parameters in the order of polymer geomembrane tension, acupuncture depth, and acupuncture density. If the permeability coefficient is normal but the tensile strength is abnormal, adjust the acupuncture parameters in the order of acupuncture depth, acupuncture density, and polymer geomembrane tension. If the permeability coefficient and tensile strength are also normal but the peel strength is abnormal, adjust the acupuncture parameters in the order of polymer geomembrane tension, acupuncture density, and acupuncture depth.

[0031] In this technical solution, during the implementation of the priority mechanism, when an abnormal permeability coefficient (<1×10) is detected simultaneously... -13 When abnormal peel strength (<14.8 kN / m) and fracture strength (<14.8 kN / m) occur, priority is given to adjusting the permeability coefficient, followed by adjusting tension -3N, needle depth -0.02 mm, and needle density -10%. If both abnormal peel strength (<0.6 kN / m) and fracture strength occur simultaneously, needle depth is adjusted first, provided the permeability coefficient is normal, followed by adjusting +0.02 mm, needle density +10%, and tension +3N. Parameter adjustment commands are securely transmitted to each actuator via the OPC UA protocol, and log information such as time, parameter type, and adjustment amount is recorded. The abnormality judgment threshold is set to: permeability coefficient control upper limit 1×10⁻⁶. -13 cm / s, lower control limit 5×10 -14 cm / s; minimum tensile strength 15 kN / m; minimum peel strength 0.7 kN / m. Conflict handling is achieved by real-time monitoring of abnormal flags through a state machine program, triggering adjustment commands according to a preset priority matrix. An instruction interlock mechanism ensures that tension adjustment is automatically paused for at least 60 seconds when the needle penetration depth increases, preventing mechanical overload. The priority mechanism reduces the incidence of severe quality defects (penetration failure) and shortens the adjustment decision time in multi-parameter conflict scenarios.

[0032] In another technical solution, the method for adjusting the acupuncture parameters includes an anti-collision mechanism, specifically: The conflict between predefined increases in needle penetration depth and decreases in needle penetration density, the conflict between increases in needle penetration density and decreases in polymer geomembrane tension, and the conflict between increases in needle penetration depth and increases in polymer geomembrane tension. When there is a conflict between increasing acupuncture depth and decreasing acupuncture density, the acupuncture depth adjustment should be performed first. When there is a conflict between increased needle density and decreased tension of polymer geomembrane, the adjustment of polymer geomembrane tension should be prioritized. When there is a conflict between increasing needle penetration depth and increasing polymer geomembrane tension, if the permeability coefficient is abnormal, the needle penetration depth should be adjusted first; if the permeability coefficient is not abnormal, the polymer geomembrane tension should be adjusted first.

[0033] In this technical solution, the anti-conflict mechanism presets three conflict types: ① conflict between increased needle penetration depth and decreased needle penetration density; ② conflict between increased needle penetration density and decreased tension; ③ conflict between simultaneous increases in needle penetration depth and tension. When type ① occurs, needle penetration depth adjustment is prioritized and the density parameter is frozen for one adjustment cycle; for type ②, tension adjustment is prioritized and the density increase is limited to ≤5%; for type ③, the selection is based on the permeability coefficient status: if permeability is abnormal, depth adjustment is prioritized (allowing tension overshoot ±2N), otherwise tension adjustment is prioritized. Conflict signals are processed by the arbitration module, and a hardware interlock circuit prevents simultaneous output of conflict commands. The conflict detection algorithm compares the adjustment command queue in real time, triggering a conflict flag when a reverse operation command is detected. Paused adjustment commands are re-evaluated after a one-cycle delay (180 seconds). The overshoot tolerance setting allows tension to temporarily exceed the limit by ±3N during conflict handling, but it must be restored within the next cycle. Historical conflict data is stored in an SQL database, and an optimization suggestion report is generated weekly. This anti-conflict mechanism reduces the number of overload alarms in the mechanical system and improves the success rate of parameter adjustments in conflict scenarios.

[0034] Example

[0035] The composite geotextile prepared using the method of this invention is as follows: I. Raw Material Selection and Pretreatment Synthetic fiber geotextiles Material: Polyester fiber (PET) nonwoven fabric, unit area weight 150~250g / m² 2 The fracture strength is ≥18kN / m, the warp density is 12~14 roots / cm, and the weft density is 10~12 roots / cm.

[0036] Polymer geomembrane Material: High-density polyethylene (HDPE), thickness 1.0~2.0mm, permeability coefficient ≤8×10 -14 cm / s.

[0037] II. Gradient Acupuncture Composite Process Lamination and Preheating Two layers of geotextile are symmetrically laid on the upper and lower surfaces of the HDPE membrane, and then sent to a gradient needle punching machine. A dual-station gradient needle punching process is adopted, with coarse needle punching for pre-reinforcement from both the upper and lower sides, and fine needle punching for finishing from both the upper and lower sides. The needle punching density is preset according to the stress requirements of different areas of the polymer geomembrane.

[0038] Differentiated acupuncture in different regions Core stress zone (accounting for 20%): Orthogonal cross-path (stitch spacing 5~8mm, angle 90°), density 35~45 stitches / cm 2 This improves the uniformity of intensity along the latitude and longitude.

[0039] Edge reinforcement zone (outer 5cm): spiral progression path (stitch spacing 3~5 mm, initial radius 10~12 mm, increasing by 1.5~2.5 mm per round), density 50~60 stitches / cm 2 This enhances the anti-peeling properties.

[0040] Weak and sensitive areas (15mm around the defect point): Circular reinforcement path (radius 1~2mm), density 60~70 stitches / cm 2 This will specifically improve the risk of weld leakage.

[0041] Regular area (60-70%): Parallel path (stitch spacing 10-15mm), density 20-30 stitches / cm 2 This ensures the overall structural stability.

[0042] Dynamic monitoring and control Sensor configuration: A laser displacement sensor (accuracy ±0.01mm) monitors the needle penetration depth in real time. When the deviation is > ±0.05mm, the servo motor adjusts its stroke.

[0043] A 5-megapixel industrial camera (30 frames per second) was used to detect needle penetration density; the deviation was >5 needles / cm. 2 The speed is adjusted by the frequency converter.

[0044] The tension sensor (range 0~200N) controls the membrane tension within a fluctuation range of ±2N, and the magnetic powder brake response time is <150ms.

[0045] Quality prediction model: A backpropagation (BP) neural network has a 3-node input layer (depth, density, tension), an 8-node hidden layer (ReLU activation), and a 3-quality index (R) for the output layer. 2 ≥0.95).

[0046] Predicted values ​​are output every 5 seconds, with a penetration coefficient > 1×10⁻⁶. -13 Parameter adjustment is triggered when the fracture strength is <14.5 kN / m or the peel strength is <0.7 kN / m.

[0047] III. Intelligent Control Parameter adjustment strategy Depth adjustment: Insufficient fracture strength → +0.02mm / time (maximum +0.2mm); Insufficient penetration → -0.02mm / time (maximum -0.2mm).

[0048] Density adjustment: Insufficient strength / peeling → increase speed by 10%; insufficient penetration → decrease speed by 10% (base speed 1500rpm ± 15%).

[0049] Tension adjustment: Insufficient peeling → +5N (current +10mA); Insufficient penetration → -3N (current -6mA).

[0050] Priority and Conflict Prevention Priority: Permeation anomaly > Fracture anomaly > Delamination anomaly. Adjust the order according to tension → depth → density or depth → density → tension.

[0051] Conflict prevention: When there is a conflict between increasing depth and decreasing density, prioritize adjusting depth; when there is a conflict between tension and density in opposite directions, prioritize adjusting tension; when there is a conflict between depth and tension in the same direction, decide based on the permeability state.

[0052] IV. Post-processing Heat setting and surface treatment Heat setting: Hot air circulation treatment at 125~135℃ for 9~11 minutes, cooling rate ≤4℃ / min, to eliminate internal stress and stabilize dimensions.

[0053] Corona treatment: power 4~6kW, treatment speed 6~8m / min, surface tension ≥40mN / m, finally obtaining composite geotextile.

[0054] Comparative Example The composite geotextile is prepared using traditional processes, as detailed below: I. Material Selection Synthetic fiber geotextiles Material: Polyester fiber (PET) nonwoven fabric, unit area weight 200g / m² 2 The fracture strength is 18 kN / m.

[0055] Polymer geomembrane Material: High-density polyethylene (HDPE), 1.2mm thick, permeability coefficient 5×10 -14 cm / s.

[0056] II. Traditional Process Steps Layering and Needling Two layers of geotextile were laid on the upper and lower surfaces of the HDPE membrane and then needle-punched directly.

[0057] Single-layer acupuncture: Acupuncture is performed only from one side, without the staged treatment of thick and thin needles.

[0058] Uniform needle punching: The entire membrane uses the same parameters, with no zoned differentiation design. Needle type: Single conical needle (0.6mm in diameter).

[0059] Needle penetration depth: 0.6 mm (50% of film thickness).

[0060] Needle density: 25 needles / cm 2(Parallel path, stitch spacing 15mm).

[0061] III. Post-processing Heat setting and surface treatment Heat setting: Hot air circulation treatment at 125~135℃ for 9~11 minutes, cooling rate ≤4℃ / min, to eliminate internal stress and stabilize dimensions.

[0062] Corona treatment: power 4~6kW, treatment speed 6~8m / min, surface tension ≥40mN / m, finally obtaining composite geotextile.

[0063] The performance of the composite geotextiles prepared in the examples and the comparative examples was tested and compared, and the results are shown in Table 1 below.

[0064] The testing standards for longitudinal and transverse tensile strength refer to GB / T 15788-2017 "Tension Test of Wide Strips for Geosynthetics". During the test, the specimen is cut along the longitudinal (warp) and transverse (weft) directions of the geotextile and made into a wide strip with a width of 200 mm and a length of 100 mm. The two ends of the wide strip are clamped by the pneumatic clamp of the tensile testing machine and stretched. The clamping pressure is 0.5 MPa to avoid slippage of the specimen. The tensile speed is 50 mm / min. The tensile force-displacement curve is recorded, and the maximum tensile force value (kN) is taken. The strength per unit width (kN / m) is calculated, which is the longitudinal and transverse tensile strength.

[0065] The test standard for interlayer peel strength refers to GB / T 2791-1995 "Test Method for Peel Strength of Adhesives". During the test, the sample is made into a wide strip of 25 mm wide × 150 mm long. The upper and lower fibers of the composite geotextile are pre-peeled from the middle membrane material by 50 mm. The peeled end is clamped, the testing machine is started, the peel angle is 180° (T-shaped peel), the tensile speed is 100 mm / min, the average force value (N) during the peeling process is recorded, and the peel strength per unit width (kN / m) is calculated, which is the interlayer peel strength.

[0066] The permeability coefficient is tested according to GB / T 19979.1-2005 "Geosynthetic Materials - Impermeability - Part 1: Determination of Hydrostatic Pressure Resistance". During the test, a 200 mm diameter circular specimen is prepared and clamped in a permeameter (such as a flexible wall permeameter), ensuring a tight seal. Gradual pressurization is applied (initial pressure 0.1 MPa, increasing by 0.05 MPa in each stage, maintained for 30 min), and the permeation rate (mL / min) at each pressure level is recorded. The test is terminated when the permeation rate suddenly increases or the specimen ruptures; the pressure at the stage before rupture is taken as the hydrostatic pressure resistance value. The formula for calculating the permeability coefficient (k) is: Where Q is the seepage volume (mL), d is the sample thickness (cm), and A is the seepage area (cm²). 2 ΔP is the pressure difference (kPa), and t is the time (s).

[0067] The test method for membrane material breakage rate is as follows: Ten 1 m² samples are randomly selected. Any visible pinholes, cracks, or delamination areas (≥1 mm²) on the membrane surface are defined as breakage. Breakage points are located through visual inspection combined with light transmission detection (backlight stage illumination). The size of the breakage is confirmed using a digital microscope (e.g., Keyence VHX-6000). The percentage of the area with breakage is calculated, which is the membrane material breakage rate.

[0068] The test method for edge peel strength is as follows: Cut the sample along the edge of the composite geotextile, ensuring the peel interface is located at the edge joint. Prepare a sample 25 mm wide × 150 mm long, with the edge area (within 5 mm of the edge) as the test zone. Clamp the sample, peel at a 90° angle, and apply a tensile speed of 50 mm / min, recording the peel force curve. Calculate the peel strength per unit width (kN / m), which is the edge peel strength.

[0069] Table 1 Comparison of the performance of composite geotextiles

[0070] Note: Membrane material breakage rate refers to the proportion of broken area to the total area.

[0071] As shown in Table 1, the traditional process in the comparative example, due to its single-layer uniform needle punching and lack of gradient reinforcement design, resulted in insufficient entanglement between the fiber and the membrane material, leading to significantly lower mechanical properties compared to the preparation process of the present invention in the examples. Regarding mechanical properties, the present invention, through the use of dual-station gradient needle punching and zoned differentiated design, achieves sufficient entanglement between the fiber and the membrane material, forming a good three-dimensional structure. This results in a longitudinal tensile strength of 28~32 kN / m and a transverse tensile strength of 25~28 kN / m, with the transverse strength reaching 96% of the longitudinal strength. The structure exhibits excellent symmetry and can better adapt to stress requirements in different directions. In terms of impermeability, the present invention effectively reduces the permeability coefficient, with an average value stable at 2×10⁻⁶. -14 ~4×10 -14 The permeability is measured in cm / s, with a very small fluctuation range of only ±10%, far lower than the fluctuation level of the traditional process in the comparative example. The permeability coefficient at the weld can also be strictly controlled within the engineering allowable value (1×10⁻⁶). -13 Within a range of (cm / s), the leakage risk is significantly reduced. Regarding process stability, this invention introduces a dynamic monitoring system that allows for real-time and precise parameter adjustment, resulting in a membrane material breakage rate as low as 2-3%, greatly reducing material waste. The rapid parameter adjustment response avoids the lag of manual adjustments, ensuring construction quality and efficiency, and fully meeting the needs of high-standard projects.

[0072] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. Other modifications can be easily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A method for preparing composite geotextiles, characterized in that, Includes the following steps: Step 1: Select two layers with a unit area mass of 100~300 g / m². 2 Synthetic fiber geotextiles with a tensile strength greater than 15 kN / m, and geotextiles with a thickness of 0.5~3.0 mm and a permeability coefficient less than 1×10⁻⁶. -13 High-molecular geomembrane with a flow rate of cm / s; Step 2: Two layers of synthetic fiber geotextile are stacked on the upper and lower surfaces of the polymer geomembrane, and then sent to a gradient needle punching machine. A dual-station gradient needle punching process is used to pre-reinforce the geomembrane with coarse needles from both the upper and lower sides at a depth of 50-60% of the thickness of the polymer geomembrane. Then, fine needles are used to finish the geomembrane from both the upper and lower sides at a depth of 70-80% of the thickness of the polymer geomembrane. The needle punching density is preset according to the stress requirements of different areas of the polymer geomembrane. During the needle punching process, the needle punching parameters are adjusted in real time through a dynamic monitoring system. The preset value for needle density is: The polymer geomembrane is divided into a core stress-bearing zone, an edge reinforcement zone, a weak and sensitive zone, and a conventional zone; among which... The preset needle density in the core stress zone is 35-45 needles / cm². 2 Orthogonal cross needle puncture path is adopted; The preset needle density in the edge reinforcement zone is 50-60 needles / cm. 2 It adopts a spiral progressive needle puncture path; The preset needle density for the weak and sensitive area is 60-70 needles / cm². 2 A ring-shaped encrypted needle penetration path is adopted; The conventional area refers to the main body excluding the core stress area, edge reinforcement area, and weak and sensitive area, accounting for 60-70% of the total area of ​​the polymer geomembrane. The preset needle-punching density is 20-30 needles / cm. 2 A uniform parallel needle puncture path is adopted; Step 3: Heat set the needle-punched geotextile. The heat setting temperature is controlled at 120~140℃ for 8~12 minutes. Then, the surface of the heat-set geotextile is treated to finally obtain the composite geotextile.

2. The method for preparing the composite geotextile as described in claim 1, characterized in that, The synthetic fiber geotextile is made of polyester fiber, and the polymer geomembrane is made of high-density polyethylene.

3. The method for preparing the composite geotextile as described in claim 1, characterized in that, The needle spacing of the orthogonal cross needle puncture path is 5-8 mm, and the angle is 90°; the needle spacing of the spiral progressive needle puncture path is 3-5 mm, and the spiral radius increases progressively; the ring radius of the annular densified needle puncture path is 1-2 mm; and the needle spacing of the uniform parallel needle puncture path is 10-15 mm.

4. The method for preparing the composite geotextile as described in claim 1, characterized in that, The dynamic monitoring system includes a displacement sensor installed on the side of the needle seat of the needle punching machine for real-time monitoring of the needle punching depth, an industrial camera installed directly above the needle punching machine for detecting the distribution density of needle punch points using an image recognition algorithm, and tension sensors installed at both ends of the polymer geomembrane conveying roller for real-time monitoring of the membrane tension.

5. The method for preparing the composite geotextile as described in claim 4, characterized in that, The dynamic monitoring system collects needle penetration depth, needle penetration density, and polymer geomembrane tension in real time, and periodically samples and tests the composite geotextile to obtain its tensile strength, permeability coefficient, and peel strength. These data, along with the collected needle penetration depth, needle penetration density, and polymer geomembrane tension, are normalized through an industrial internet platform to establish a prediction model based on a BP neural network. The training sample size of the prediction model is ≥1000 groups, and R0... 2 ≥0.95, the system predicts the quality of composite geotextile by analyzing the results of the model in real time. When the prediction results exceed the preset control range, the system automatically adjusts the needle punching parameters.

6. The method for preparing the composite geotextile as described in claim 5, characterized in that, The specific method for adjusting the acupuncture parameters is as follows: Needle depth adjustment: Based on the deviation between the predicted result and the control range, the depth is adjusted in increments of 0.02 mm, with a maximum adjustment range of ±0.2 mm and an adjustment cycle of 3 min. If the predicted fracture strength is lower than the control limit, the needle depth is increased by 0.02 mm; if the predicted permeability coefficient is lower than the control limit, the needle depth is decreased by 0.02 mm. Needle density adjustment: The needle density is changed by adjusting the motor speed of the needle punching machine through a frequency converter. The adjustment range is ±15% based on the reference speed. If the predicted fracture strength or peel strength is lower than the control limit, the operating speed of the needle punching machine is increased by 10%. If the predicted penetration coefficient is lower than the control limit, the operating speed of the needle punching machine is decreased by 10%. Adjustment of polymer geomembrane tension: Adjustment is made according to the deviation between the predicted results and the control range. If the predicted peel strength is lower than the control limit, the tension of the polymer geomembrane is increased by 5 N. If the predicted permeability coefficient is lower than the control limit, the tension of the polymer geomembrane is decreased by 3 N.

7. The method for preparing the composite geotextile as described in claim 6, characterized in that, The method for adjusting the acupuncture parameters has a priority mechanism, specifically: setting a lower limit for the control of the permeability coefficient, the lower limit for the fracture strength, and the lower limit for the peel strength; when the predicted permeability coefficient is less than the lower limit, the predicted fracture strength is less than the lower limit, and the predicted peel strength is less than the lower limit, the corresponding indicators are judged to be abnormal respectively. When multiple anomalies occur simultaneously, parameter adjustments are performed in the order of priority: permeability coefficient anomaly > fracture strength anomaly > peel strength anomaly. If the permeability coefficient is abnormal, adjust the acupuncture parameters in the order of polymer geomembrane tension, acupuncture depth, and acupuncture density; if the permeability coefficient is normal but the tensile strength is abnormal, adjust the acupuncture parameters in the order of acupuncture depth and acupuncture density; if the permeability coefficient and tensile strength are also normal but the peel strength is abnormal, adjust the acupuncture parameters in the order of polymer geomembrane tension and acupuncture density.

8. The method for preparing the composite geotextile as described in claim 6, characterized in that, The method for adjusting the acupuncture parameters has an anti-conflict mechanism, specifically: The conflict between predefined increases in needle penetration depth and decreases in needle penetration density, the conflict between increases in needle penetration density and decreases in polymer geomembrane tension, and the conflict between increases in needle penetration depth and increases in polymer geomembrane tension. When there is a conflict between increasing acupuncture depth and decreasing acupuncture density, the acupuncture depth adjustment should be performed first. When there is a conflict between increased needle density and decreased tension of polymer geomembrane, the adjustment of polymer geomembrane tension should be prioritized. When there is a conflict between increasing needle penetration depth and increasing polymer geomembrane tension, if the permeability coefficient is abnormal, the needle penetration depth should be adjusted first; if the permeability coefficient is not abnormal, the polymer geomembrane tension should be adjusted first.

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