Structural design and forming process of anti-settling MPP non-excavation jacking pipe
By using ultrasonic impregnation pretreatment and ultrasonic mixing of short-cut carbon fiber reinforced phase, combined with multi-stage temperature-controlled plasticization and gradient cooling, the problem of poor uniformity in MPP trenchless pipe jacking structure was solved, and the anti-settlement ability and long-term structural stability of the jacking pipe were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-03-31
AI Technical Summary
The structural design and molding process of MPP trenchless pipe jacking result in poor internal structural uniformity, insufficient deformation resistance to uneven ground settlement, and inadequate long-term structural stability.
The ultrasonic impregnation pretreatment and ultrasonic mixing of short-cut carbon fiber reinforced phase are combined with multi-stage temperature-controlled plasticizing and ultrasonic-assisted extrusion. The interlayer melting and fusion of the three-layer material is achieved through the interface fusion channel. With gradient cooling and online annealing, the internal stress is released.
It improves the uniformity of the internal structure of the pipe jacking, reduces residual stress, enhances the pipe jacking's resistance to settlement and long-term structural stability, and adapts to the service requirements of complex geological environments.
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Figure CN121756645A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of MPP trenchless pipe jacking technology, and more specifically, to the structural design and forming process of anti-settlement MPP trenchless pipe jacking. Background Technology
[0002] Trenchless pipe jacking technology, as an underground pipeline laying technology that does not require large-scale excavation of the ground surface, is widely used in underground pipeline projects such as municipal water supply and drainage, communications, and gas due to its advantages such as minimal interference with the surrounding environment, high construction efficiency, and controllable overall costs. MPP material, with its excellent properties such as high temperature resistance, corrosion resistance, good toughness, and light weight, has become the core material for trenchless pipe jacking. Its structural stability and mechanical properties after molding directly determine the service life of the jacking pipe in complex geological environments.
[0003] In related technologies, the structural design of MPP trenchless pipe jacking often adopts a single hollow circular pipe or a simple outer corrugated structure. The corresponding molding process usually includes raw material mixing, extrusion molding, and cooling and shaping, which results in poor uniformity of the internal structure of the jacking pipe, leading to insufficient deformation resistance to uneven ground settlement and insufficient long-term structural stability. Summary of the Invention
[0004] To address the problem in related technologies where the structure and molding of MPP trenchless jacking pipes result in poor internal structural uniformity, leading to insufficient deformation resistance to uneven ground settlement and inadequate long-term structural stability, this application provides a structural design and molding process for settlement-resistant MPP trenchless jacking pipes.
[0005] The structural design and forming process of the anti-settlement MPP trenchless jacking pipe provided in this application adopt the following technical solution: The structural design and forming process of anti-settlement MPP trenchless pipe jacking includes the following steps: Processing and mixing: The short-cut carbon fiber reinforcing phase is subjected to ultrasonic impregnation pretreatment at 25-40kHz to form a reinforcing material. The inner layer material, middle layer material and outer layer material are respectively ultrasonically mixed with the reinforcing material at a power of 500-800W to obtain inner layer mixture, middle layer mixture and outer layer mixture. Temperature-controlled extrusion: The inner layer mixture, middle layer mixture and outer layer mixture are respectively subjected to temperature-controlled plasticization at 160-210℃, and then extruded with ultrasonic power of 600-900W and screw speed of 30-50r / min, and melt pressure of 5-15MPa, to form inner extruded material, middle extruded material and outer extruded material. Composite molding: The inner extrusion material, middle extrusion material and outer extrusion material are fed according to the preset flow ratio, and after interlayer fusion at 190-200℃ through the interface fusion channel, they are extruded to form a composite tube blank. Cooling and shaping: The composite tube blank is cooled in a gradient at a rate of 5-8℃ / s, and then annealed online at 100-120℃ before being cut to a fixed length.
[0006] By adopting the above technical solution, the ultrasonic impregnation pretreatment and ultrasonic mixing of the short-cut carbon fiber reinforcement phase are combined to break the agglomeration of the reinforcement phase, so that the reinforcement phase is uniformly dispersed in each layer of raw materials. Through multi-stage temperature-controlled plasticization and ultrasonic-assisted extrusion, combined with the control of screw speed and melt pressure, the material is fully plasticized and homogenized. The three layers of material are melted and fused together through the interface fusion channel to form a composite tube blank with an integrated structure. The material crystallization process is controlled by gradient cooling and combined with online annealing to release internal stress. Therefore, the uniformity of the internal structure of the jacking pipe is improved and the residual stress is reduced. This solves the problem in related technologies where the structure and molding of MPP trenchless jacking pipes result in poor uniformity of the internal structure of the jacking pipe, leading to insufficient deformation capacity and long-term structural stability against uneven ground settlement.
[0007] Preferably, in the processing mixing step, the ultrasonic impregnation pretreatment involves preparing a silane coupling agent ethanol solution at a volume ratio of 1%-2%, with a mass-to-volume ratio of 1g:10-20mL for the short-cut carbon fibers and the silane coupling agent ethanol solution. The ultrasonic treatment time is 10-15min, and the ultrasonically impregnated short-cut carbon fiber reinforcing phase is dried in a vacuum environment at 80-90℃ for 15-20min and then cooled to room temperature.
[0008] By adopting the above technical solution, the silane coupling agent ethanol solution and ultrasonic treatment work synergistically to allow the coupling agent to uniformly coat the surface of the short-cut carbon fiber. Vacuum drying removes residual impurities and moisture, further improving the compatibility of the reinforcing phase with each layer of raw materials and reducing interface defects.
[0009] Preferably, in the processing and mixing step, the inner layer material is composed of MPP, antioxidant, and lubricant in a mass ratio of 95-98:1-3:1-2; the middle layer material is composed of MPP and coupling agent in a mass ratio of 97-99:1-3; and the outer layer material is composed of MPP and polyurethane modifier in a mass ratio of 90-95:5-10. During ultrasonic mixing, the mass ratio of the inner layer material to the reinforcing material is 95:5-90:10, the mass ratio of the middle layer material to the reinforcing material is 75:25-85:15, and the mass ratio of the outer layer material to the reinforcing material is 95:5-90:10.
[0010] By adopting the above technical solution, the composition ratio of the three layers of raw materials is adapted to their functional requirements and matched with the ratio of reinforcing materials. This allows the inner layer to ensure basic toughness, the middle layer to strengthen the resistance to deformation, and the outer layer to improve wear resistance. Each layer works synergistically to improve the comprehensive mechanical properties and anti-settlement adaptability of the jacking pipe.
[0011] Preferably, in the processing mixing step, the ultrasonic mixing involves preheating the mixer to 85-95°C, using an ultrasonic power of 500-600W and a mixing time of 23-27 minutes at a rotation speed of 900-950 r / min, using an ultrasonic power of 600-700W and a mixing time of 20-24 minutes at a rotation speed of 1000-1050 r / min, and using an ultrasonic power of 700-800W and a mixing time of 18-22 minutes at a rotation speed of 1100-1150 r / min. Furthermore, if the temperature of any material exceeds 95-100°C during ultrasonic mixing, the ultrasonic power is reduced by 50-100W. After ultrasonic mixing is completed, the inner layer mixture, middle layer mixture, and outer layer mixture are stored in sealed silos with a relative humidity ≤60% and a temperature of 40-50°C.
[0012] By adopting the above technical solutions, through the linkage of speed, power and time, combined with the preheating and temperature protection of the mixer, the mixing process is ensured to be stable and controllable, the material homogenization effect is consistent, and the sealed constant temperature storage environment avoids the material from absorbing moisture or fluctuating its performance.
[0013] Preferably, in the temperature-controlled extrusion step, the specific temperatures for temperature-controlled plasticizing are 160-165℃ in the feeding section, 180-185℃ in the compression section, 205-210℃ in the melting section, 190-195℃ in the ultrasonic homogenization section, and 195-200℃ in the die head section.
[0014] By adopting the above technical solution, the MPP is adapted to the entire plasticization process from preheating, compression, melting to homogenization and discharge through segmented gradient temperature control, ensuring that the material is fully plasticized and the melt state is uniform and stable.
[0015] Preferably, in the temperature-controlled extrusion step, the ultrasonic power is 600-650W when the screw speed is 30-35r / min, 650-700W when the screw speed is 35-40r / min, 700-800W when the screw speed is 40-45r / min, and 800-900W when the screw speed is 45-50r / min. The feeding rate during extrusion is 50-200kg / h.
[0016] By adopting the above technical solution, the linkage between screw speed and ultrasonic power, combined with a stable feeding speed, is used to match the plasticization, homogenization and discharge efficiency of the material, avoid fluctuations in melt pressure or state, and ensure the consistency of the inner, middle and outer three-layer extruded material.
[0017] Preferably, in the composite molding step, the preset flow ratio of the inner extruder, the middle extruder, and the outer extruder is 5.5-6.5:2.5-3.5:0.8-1.2, the interface fusion channel is provided with a spiral turbulence boss with a height of 2-3 mm and a pitch of 10-15 mm, the interlayer fusion mixing time is 5-10 s, and the die outlet pressure during extrusion is 5-15 MPa.
[0018] By adopting the above technical solution, and through the coordinated flow ratio of the three-layer structure and the spiral turbulence boss, the convection mixing of the three-layer molten materials is enhanced, the mold outlet pressure is stably controlled, and the interlayer fusion is more complete and the transition is smoother, forming a composite tube blank with an integrated structure.
[0019] Preferably, in the cooling and shaping step, the gradient cooling includes a pre-cooling section, a transition section, and a shaping section. The temperature of the pre-cooling section is 95-105℃ and the cooling time is 12-18s. The temperature of the transition section is 55-65℃ and the cooling time is 18-22s. The temperature of the shaping section is 25-35℃ and the cooling time is 23-27s. The initial traction speed of the gradient cooling is 0.8-1.2m / min, and for every 0.4-0.6m / min increase in traction speed, the temperature of the pre-cooling section and the transition section decreases by 4-6℃. After the gradient cooling, the surface temperature of the composite tube blank is 30-40℃.
[0020] By adopting the above technical solution, the segmented gradient cooling and traction speed are linked and controlled to allow the composite tube blank to crystallize slowly and uniformly, avoiding uneven crystallization and stress accumulation caused by cooling, while ensuring the dimensional accuracy of the tube blank and improving the structural stability and dimensional consistency of the jacking pipe.
[0021] Preferably, in the cooling and shaping step, the initial time of the online annealing is 5-10 min. When the residual stress is >5 MPa, the annealing temperature is increased by 5-10℃ and the annealing time is extended by 2-3 min. When the residual stress is ≤5 MPa, the initial parameters are maintained, and the composite tube blank is naturally cooled to 20-30℃ after annealing.
[0022] By adopting the above technical solution and adjusting the dynamic annealing parameters based on residual stress monitoring, the stress accumulated inside the tube blank can be released. Combined with subsequent natural cooling, the residual stress level can be further reduced, the structural stability of the jacking pipe during long-term use can be improved, and the risk of cracking caused by stress release can be reduced.
[0023] Preferably, in the cooling and shaping step, the cutting length of the fixed-length cutting is 6-12m / section, and the end face of the composite tube blank is polished after cutting. By adopting the above technical solutions, fixed-length cutting ensures the consistency of pipe section length, and end face grinding removes burrs and ensures flatness, which not only facilitates subsequent construction and connection, but also avoids stress concentration caused by end face defects.
[0024] In summary, this application has the following beneficial effects: 1. Because this application uses a combination of ultrasonic impregnation pretreatment and ultrasonic mixing of short-cut carbon fiber reinforcement phase, the agglomeration state of the reinforcement phase is broken, so that the reinforcement phase is uniformly dispersed in each layer of raw material. Through multi-stage temperature-controlled plasticization and ultrasonic-assisted extrusion, combined with the control of screw speed and melt pressure, the material is fully plasticized and the homogenization effect is consistent. The three layers of material are melted and fused through the interface fusion channel to form a composite tube blank with integrated structure. The material crystallization process is controlled by gradient cooling and the internal stress is released by online annealing. Therefore, the uniformity of the internal structure of the top tube is improved and the residual stress is reduced.
[0025] 2. In this application, ultrasonic impregnation pretreatment with silane coupling agent ethanol solution is used to uniformly coat the surface of short-cut carbon fibers with coupling agent, improve the compatibility between the reinforcing phase and the MPP substrate, adapt the flow ratio of the three-layer structure function and the synergistic effect of the spiral turbulence boss, prolong the interlayer contact time and expand the contact area, so that the three-layer materials can achieve deep melting and fusion to form an integrated composite structure, making the interlayer transition of the jacking pipe smooth and without obvious interface, improving the interlayer peel strength, enhancing the overall structural integrity, effectively resisting the shear force generated by ground subsidence, and avoiding interlayer separation or structural fracture.
[0026] 3. This application adopts segmented temperature and time control, combined with traction speed linkage, to allow the composite tube blank to cool slowly from the molten state, avoiding uneven crystallization and stress accumulation caused by rapid cooling. The online annealing starts at 100-120℃, and the parameters are dynamically adjusted according to the residual stress monitoring results to release the internal stress generated during the cooling process in a targeted manner. The structure is further stabilized by natural cooling, which reduces the residual stress of the jacking pipe. During long-term use, it is not easy to crack or deform due to stress release, thus improving the structural stability and adapting to the long-term service requirements of complex underground environments. Attached Figure Description
[0027] Figure 1 This is a flowchart of the structural design and forming process of the anti-settlement MPP trenchless jacking pipe provided in this application. Detailed Implementation
[0028] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.
[0029] Technical concept: In related technologies, MPP trenchless pipe jacking mostly adopts a single hollow round pipe or a simple outer corrugated structure. The molding process only includes basic raw material mixing, extrusion molding and cooling and shaping. The raw material mixing lacks targeted homogenization methods, the reinforcing phase is prone to agglomeration and has insufficient compatibility with the substrate. The layers of the composite structure are only physically bonded and do not form effective fusion. At the same time, the cooling process is mostly rapid cooling, resulting in poor uniformity of the internal structure of the jacking pipe, obvious accumulation of residual stress, and difficulty in adapting to the requirements of resisting uneven settlement in complex geological environments.
[0030] Based on the above problems, this application constructs a full-process molding process through multi-stage collaborative design. First, the short-cut carbon fiber reinforcement phase is subjected to ultrasonic impregnation pretreatment, combined with ultrasonic mixing with triple linkage of rotation speed, power and time, to achieve uniform dispersion of the reinforcement phase and improve compatibility with the substrate. Then, multi-stage temperature-controlled ultrasonic-assisted extrusion, combined with an interface fusion channel with spiral turbulence bosses, ensures that the three layers of materials are fully plasticized and achieve interlayer fusion. Finally, gradient cooling is used to control the crystallization process, combined with online annealing based on dynamic adjustment parameters of residual stress, to effectively release internal stress, and ultimately solve the technical problems of poor uniformity and insufficient anti-settlement ability of the jacking pipe structure.
[0031] Unless otherwise specified, all experimental methods used below are conventional methods. All materials, reagents, methods, and instruments used, unless otherwise specified, are conventional materials, reagents, methods, and instruments in this field, which can be obtained commercially or prepared according to literature methods by those skilled in the art.
[0032] To better understand the above technical solutions, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments.
[0033] The following is a further description with reference to the embodiments: Example 1: Structural design and forming process of anti-settlement MPP trenchless pipe jacking, including the following steps: Processing and mixing: The short-cut carbon fiber reinforcement phase is subjected to ultrasonic impregnation pretreatment at 32.5kHz to form a reinforcement material. The inner layer material, middle layer material and outer layer material are ultrasonically mixed with the reinforcement material at a power of 650W to obtain the inner layer mixture, middle layer mixture and outer layer mixture. Temperature-controlled extrusion: The inner layer mixture, middle layer mixture and outer layer mixture are respectively subjected to temperature-controlled plasticization at 185℃, and then extruded with ultrasonic power of 750W, screw speed of 40r / min and melt pressure of 10MPa to form inner extruded material, middle extruded material and outer extruded material. Composite molding: The inner extrusion material, middle extrusion material and outer extrusion material are fed according to the preset flow ratio, and after interlayer fusion at 190-200℃ through the interface fusion channel, they are extruded to form a composite tube blank. Cooling and shaping: The composite tube blank is subjected to gradient cooling at a rate of 6.5℃ / s, followed by online annealing at 110℃ and then cut to a fixed length.
[0034] In the processing mixing step, the ultrasonic impregnation pretreatment involves preparing a silane coupling agent ethanol solution at a volume ratio of 1.5%, with a mass-to-volume ratio of 1g:15mL for the short-cut carbon fibers and the silane coupling agent ethanol solution. The ultrasonic treatment time is 12.5min, and the ultrasonically impregnated short-cut carbon fiber reinforcement phase is dried in a vacuum environment at 85℃ for 17.5min and then cooled to room temperature.
[0035] In the mixing process, the inner layer material consists of MPP, antioxidant, and lubricant in a mass ratio of 96.5:2:1.5; the middle layer material consists of MPP and coupling agent in a mass ratio of 98:2; and the outer layer material consists of MPP and polyurethane modifier in a mass ratio of 92.5:7.5. During ultrasonic mixing, the mass ratio of the inner layer material to the reinforcing material is 92.5:7.5, the mass ratio of the middle layer material to the reinforcing material is 80:20, and the mass ratio of the outer layer material to the reinforcing material is 92.5:7.5.
[0036] In the processing mixing step, ultrasonic mixing involves preheating the mixer to 90℃, using an ultrasonic power of 550W and a mixing time of 25min at a speed of 925r / min, 650W and 22min at a speed of 1025r / min, and 750W and 20min at a speed of 1125r / min. During ultrasonic mixing, if the temperature of any material exceeds 97℃, the ultrasonic power is reduced by 75W. After ultrasonic mixing, the inner layer, middle layer, and outer layer mixtures are stored in sealed silos with a relative humidity of ≤60% and a temperature of 45℃.
[0037] In the temperature-controlled extrusion step, the specific temperatures for temperature-controlled plasticizing are: 162.5℃ in the feeding section, 182.5℃ in the compression section, 207.5℃ in the melting section, 192.5℃ in the ultrasonic homogenization section, and 197.5℃ in the die head section.
[0038] In the temperature-controlled extrusion process, the ultrasonic power is 625W when the screw speed is 32.5r / min, 675W when the screw speed is 37.5r / min, 750W when the screw speed is 42.5r / min, and 850W when the screw speed is 47.5r / min. The feeding speed during extrusion is 125kg / h.
[0039] In the composite molding process, the preset flow ratio of the inner extruder, the middle extruder, and the outer extruder is 6:3:1. The interface fusion channel is equipped with a spiral turbulence boss with a height of 2.5 mm and a pitch of 12.5 mm. The interlayer fusion mixing time is 8 s, and the die outlet pressure during extrusion is 10 MPa.
[0040] In the cooling and shaping step, gradient cooling includes a pre-cooling section, a transition section, and a shaping section. The temperature of the pre-cooling section is 100℃ and the cooling time is 15s. The temperature of the transition section is 60℃ and the cooling time is 20s. The temperature of the shaping section is 30℃ and the cooling time is 25s. The initial traction speed of gradient cooling is 1m / min. For every 0.5m / min increase in traction speed, the temperature of the pre-cooling section and the transition section decreases by 5℃. After gradient cooling, the surface temperature of the composite tube blank is 35℃.
[0041] In the cooling and shaping step, the initial time for online annealing is 7.5 min. When the residual stress is >5 MPa, the annealing temperature is increased by 7.5℃ and the annealing time is extended by 2.5 min. When the residual stress is ≤5 MPa, the initial parameters are maintained, and the composite tube blank is naturally cooled to 20-30℃ after annealing.
[0042] During the cooling and shaping process, the cutting length for fixed-length cutting is 9m / section, and the end face of the composite tube blank is polished after cutting.
[0043] Example 2: This example differs from Example 1 above in that: The structural design and forming process of anti-settlement MPP trenchless pipe jacking includes the following steps: Processing and mixing: The short-cut carbon fiber reinforcement phase is subjected to 40kHz ultrasonic impregnation pretreatment to form reinforcement material. The inner layer material, middle layer material and outer layer material are respectively ultrasonically mixed with the reinforcement material at a power of 800W to obtain inner layer mixture, middle layer mixture and outer layer mixture. Temperature-controlled extrusion: The inner layer mixture, middle layer mixture and outer layer mixture are respectively subjected to temperature-controlled plasticization at 210℃, and then extruded with ultrasonic power of 900W and screw speed of 50r / min, and melt pressure of 15MPa, to form inner extruded material, middle extruded material and outer extruded material. Composite molding: The inner extrusion material, middle extrusion material and outer extrusion material are fed according to the preset flow ratio, and after interlayer fusion at 200℃ through the interface fusion channel, they are extruded to form a composite tube blank; Cooling and shaping: The composite tube blank is subjected to gradient cooling at a rate of 8℃ / s, followed by online annealing at 120℃ and then cut to a fixed length.
[0044] Example 3: This example differs from Example 1 above in that: The structural design and forming process of anti-settlement MPP trenchless pipe jacking includes the following steps: Processing and mixing: The short-cut carbon fiber reinforcement phase is subjected to 25kHz ultrasonic impregnation pretreatment to form reinforcement material. The inner layer material, middle layer material and outer layer material are respectively ultrasonically mixed with the reinforcement material at a power of 500W to obtain inner layer mixture, middle layer mixture and outer layer mixture. Temperature-controlled extrusion: The inner layer mixture, middle layer mixture and outer layer mixture are respectively subjected to temperature-controlled plasticization at 160℃, and then extruded with ultrasonic power of 600W, screw speed of 30-50r / min, and melt pressure of 5MPa to form inner extruded material, middle extruded material and outer extruded material. Composite molding: The inner extrusion material, middle extrusion material and outer extrusion material are fed according to the preset flow ratio, and after interlayer fusion at 190°C through the interface fusion channel, they are extruded to form a composite tube blank; Cooling and shaping: The composite tube blank is cooled in a gradient at a rate of 5℃ / s, then annealed online at 100℃, and finally cut to a fixed length.
[0045] Example 4: This example differs from Example 1 above in that: During the ultrasonic mixing process, the mixer is preheated to 90°C. At a rotation speed of 930 r / min, the ultrasonic power was 580 W and the mixing time was 24 min. At a rotation speed of 1030 r / min, the ultrasonic power was 660 W and the mixing time was 21 min. At a rotation speed of 1130 r / min, the ultrasonic power was 760 W and the mixing time was 19 min. When the material temperature exceeds 97℃, the ultrasonic power decreases by 80W; The rest is the same as in Example 1.
[0046] Example 5: This example differs from Example 1 above in that: In the composite molding process, the height of the spiral turbulence boss in the interface fusion channel is 2.8 mm and the pitch is 13 mm. The rest is the same as in Example 1.
[0047] Comparative Example 1: A structural design and forming process for an MPP trenchless pipe jacking system, comprising the following steps: Raw material mixing: MPP granules are mixed in a conventional high-speed mixer at 85℃ and 800r / min for 20min to obtain a mixture. Single-screw extrusion: The mixture is fed into a single-screw extruder, the barrel temperature is controlled at 170~200℃, the screw speed is 35r / min, the melt pressure is 8MPa, and a single-layer tube blank is directly extruded.
[0048] Cooling and cutting: After cooling the single-layer tube blank at a rate of 10℃ / s, it is cut to a fixed length.
[0049] Comparative Example 2: This comparative example differs from Example 1 above in that: In the processing and mixing step, the short-cut carbon fiber reinforcement phase was not ultrasonically impregnated with silane coupling agent ethanol solution, but was directly ultrasonically mixed with the inner layer material, middle layer material and outer layer material according to the mass ratio of Example 1; The rest is the same as in Example 1.
[0050] Comparative Example 3: This comparative example differs from Example 1 above in that: In the composite molding process, no spiral turbulence bosses are set in the interface fusion channel; it is only a smooth channel. The rest is the same as in Example 1.
[0051] Comparative Example 4: This comparative example differs from Example 1 above in that: During the cooling and shaping process, there is no gradient cooling; instead, 25°C cold water is sprayed directly for cooling at a rate of 12°C / s. There is no linkage between the traction speed and the cooling temperature. The rest is the same as in Example 1.
[0052] Comparative Example 5: This comparative example differs from Example 1 above in that: In the cooling and shaping process, after gradient cooling, the material is directly cut to a fixed length without an online annealing step. The rest is the same as in Example 1.
[0053] Performance testing: Interlayer peel strength: Performed according to GB / T 8808-1988 "Test Method for Peel Strength of Flexible Composite Plastic Materials", test speed 10mm / min, and take the average value of 5 test points; Residual stress: The residual stress was measured using a fiber Bragg grating residual stress sensor with a measurement accuracy of ±0.1MPa. The average value of three different positions on the circumference of the tube blank was taken. Crystallinity: The differential scanning calorimetry (DSC) method was used for testing, in accordance with GB / T 19466.3-2004 "Differential Scanning Calorimetry (DSC) for Plastics - Part 3: Determination of Melting and Crystallization Temperatures and Enthalpy"; Radial compressive strength: Adjusted according to GB / T 14152-2001 "Test method for resistance to external impact of thermoplastic pipes - clockwise rotation method", with a test loading speed of 5 mm / min, and the average value of 3 samples is taken; Roundness error: Tested using a roundness measuring instrument, with a measurement range of 0~2000mm and an accuracy of ±0.01mm. The average value of three sections, namely the two ends and the middle of the tube blank, is taken.
[0054] Test samples: Anti-settlement MPP trenchless jacking pipes prepared in Examples 1-5 and Comparative Examples 1-5, with an outer diameter of 500 mm, a wall thickness of 25 mm, and a length of 9 m / section. Three sections of each type of sample were randomly selected, and three test sections were selected from each section.
[0055] Table 1
[0056] As can be seen from Examples 1-5 and Comparative Example 1, and Table 1, this application adopts a full-process synergistic process scheme of short-cut carbon fiber ultrasonic impregnation pretreatment, ultrasonic synergistic mixing, multi-stage temperature-controlled extrusion, composite molding with spiral turbulence boss, gradient cooling and online annealing, so as to make the structure of the jacking pipe more uniform and the mechanical properties more stable.
[0057] Based on Example 1 and Comparative Example 2, and in conjunction with Table 1, it can be seen that the ultrasonic impregnation pretreatment of short-cut carbon fibers can affect the performance of the jacking pipe. The treatment method of ultrasonic impregnation with silane coupling agent ethanol solution followed by vacuum drying can improve the compatibility between the reinforcing phase and each layer of raw materials, make the interlayer bonding tighter, and optimize the overall performance of the jacking pipe.
[0058] Combining Example 1 and Comparative Example 3 with Table 1, it can be seen that the spiral turbulence protrusions in the interface fusion channel can promote interlayer fusion. By adopting an interface fusion channel with spiral turbulence protrusions of specific height and pitch, the three layers of molten material can be fully convected and mixed, resulting in more uniform interlayer fusion, reduced interface defects, and improved integrity of the jacking pipe structure.
[0059] As can be seen from Example 1 and Comparative Example 4, and Table 1, the rate control of gradient cooling can affect the performance of the jacking pipe. By using gradient cooling of 5-8℃ / s combined with segmented temperature and time control, the material can be fully crystallized, internal stress accumulation can be reduced, and the stability and dimensional accuracy of the jacking pipe structure can be improved.
[0060] As can be seen from Example 1 and Comparative Example 5, and Table 1, the online annealing step can reduce the residual stress of the jacking pipe. The online annealing method, which uses an initial temperature of 100-120℃ and dynamically adjusts the parameters according to the residual stress, effectively releases the residual stress generated during the cooling process and improves the structural stability and compressive strength of the jacking pipe for long-term use.
[0061] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. The structural design and forming process of anti-settlement MPP trenchless pipe jacking, characterized in that, Includes the following steps: Processing and mixing: The short-cut carbon fiber reinforcing phase is subjected to ultrasonic impregnation pretreatment at 25-40kHz to form a reinforcing material. The inner layer material, middle layer material and outer layer material are respectively ultrasonically mixed with the reinforcing material at a power of 500-800W to obtain inner layer mixture, middle layer mixture and outer layer mixture. Temperature-controlled extrusion: The inner layer mixture, middle layer mixture and outer layer mixture are respectively subjected to temperature-controlled plasticization at 160-210℃, and then extruded with ultrasonic power of 600-900W and screw speed of 30-50r / min, and melt pressure of 5-15MPa, to form inner extruded material, middle extruded material and outer extruded material. Composite molding: The inner extrusion material, middle extrusion material and outer extrusion material are fed according to the preset flow ratio, and after interlayer fusion at 190-200℃ through the interface fusion channel, they are extruded to form a composite tube blank. Cooling and shaping: The composite tube blank is cooled in a gradient at a rate of 5-8℃ / s, and then annealed online at 100-120℃ before being cut to a fixed length.
2. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the processing mixing step, the ultrasonic impregnation pretreatment involves preparing a silane coupling agent ethanol solution at a volume ratio of 1%-2%, with a mass-to-volume ratio of 1g:10-20mL for the short-cut carbon fibers and the silane coupling agent ethanol solution. The ultrasonic treatment time is 10-15min, and the ultrasonically impregnated short-cut carbon fiber reinforcement phase is dried in a vacuum environment at 80-90℃ for 15-20min and then cooled to room temperature.
3. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the processing and mixing step, the inner layer material is composed of MPP, antioxidant, and lubricant in a mass ratio of 95-98:1-3:1-2; the middle layer material is composed of MPP and coupling agent in a mass ratio of 97-99:1-3; and the outer layer material is composed of MPP and polyurethane modifier in a mass ratio of 90-95:5-10. During ultrasonic mixing, the mass ratio of the inner layer material to the reinforcing material is 95:5-90:10, the mass ratio of the middle layer material to the reinforcing material is 75:25-85:15, and the mass ratio of the outer layer material to the reinforcing material is 95:5-90:
10.
4. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the aforementioned processing and mixing steps, the ultrasonic mixing involves preheating the mixer to 85-95℃, using an ultrasonic power of 500-600W at a rotation speed of 900-950r / min and a mixing time of 23-27min, using an ultrasonic power of 600-700W at a rotation speed of 1000-1050r / min and a mixing time of 20-24min, and using an ultrasonic power of 700-800W at a rotation speed of 1100-1150r / min and a mixing time of 18-22min. Furthermore, if the temperature of any material exceeds 95-100℃ during ultrasonic mixing, the ultrasonic power is reduced by 50-100W. After ultrasonic mixing is completed, the inner layer, middle layer, and outer layer mixtures are stored separately in sealed silos with a relative humidity ≤60% and a temperature of 40-50℃.
5. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the temperature-controlled extrusion step, the specific temperatures for temperature-controlled plasticizing are: 160-165℃ in the feeding section, 180-185℃ in the compression section, 205-210℃ in the melting section, 190-195℃ in the ultrasonic homogenization section, and 195-200℃ in the die head section.
6. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the temperature-controlled extrusion step, the ultrasonic power is 600-650W when the screw speed is 30-35r / min, 650-700W when the screw speed is 35-40r / min, 700-800W when the screw speed is 40-45r / min, and 800-900W when the screw speed is 45-50r / min. The feeding rate during extrusion is 50-200kg / h.
7. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the composite molding step, the preset flow ratio of the inner extruder, the middle extruder, and the outer extruder is 5.5-6.5:2.5-3.5:0.8-1.2, respectively. The interface fusion channel is provided with a spiral turbulence boss with a height of 2-3 mm and a pitch of 10-15 mm. The mixing time of the interlayer fusion is 5-10 s. The die outlet pressure during extrusion is 5-15 MPa.
8. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the cooling and shaping step, the gradient cooling includes a pre-cooling section, a transition section, and a shaping section. The temperature of the pre-cooling section is 95-105℃ and the cooling time is 12-18s. The temperature of the transition section is 55-65℃ and the cooling time is 18-22s. The temperature of the shaping section is 25-35℃ and the cooling time is 23-27s. The initial traction speed of the gradient cooling is 0.8-1.2m / min, and for every 0.4-0.6m / min increase in traction speed, the temperature of the pre-cooling section and the transition section decreases by 4-6℃. After the gradient cooling, the surface temperature of the composite tube blank is 30-40℃.
9. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the cooling and shaping step, the initial time of online annealing is 5-10 min. When the residual stress is >5 MPa, the annealing temperature is increased by 5-10℃ and the annealing time is extended by 2-3 min. When the residual stress is ≤5 MPa, the initial parameters are maintained, and the composite tube blank is naturally cooled to 20-30℃ after annealing.
10. The structural design and forming process of the anti-settlement MPP trenchless jacking pipe according to claim 1, characterized in that: In the cooling and shaping step, the cutting length of the fixed-length cutting is 6-12m / section, and the end face of the composite tube blank is polished after cutting.