Intelligent rock base composite well lid for rock base multi-gas detection

Abstract

This invention discloses a smart rock-based composite manhole cover with multi-gas detection, relating to the field of composite material technology. It includes a detection breathing layer, a micro-protective chamber layer, a smart core sealing layer, and a load-bearing and energy-harvesting layer. The detection breathing layer comprises a bottom protective layer and a gas collection area, located in the center of the bottom protective layer, with several gas collection holes. The micro-protective chamber layer is positioned above the gas collection area and includes a ceramic cavity and a primary rock-based filling layer. The smart core sealing layer, positioned above the micro-protective chamber layer, includes a microcontroller, a wireless communication module, a rechargeable battery pack, and a secondary rock-based filling layer. The load-bearing and energy-harvesting layer is positioned above the smart core sealing layer. The smart rock-based composite manhole cover mentioned in this application combines high strength, low water absorption, hydrophobic and breathable properties, and explosion-proof and flame-retardant characteristics, adapting to the protection requirements of built-in gas sensors and electronic components.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a rock-based multi-gas detection intelligent rock-based composite manhole cover. Background Technology

[0002] Rock-based composite materials have been gradually applied in the manufacturing of manhole covers due to their readily available raw materials, low cost, and good load-bearing capacity. However, existing ordinary rock-based composite materials have significant performance shortcomings when used in multi-gas detection smart manhole covers: insufficient toughness, easy to crack, and unable to withstand heavy municipal crushing; high water absorption rate, which can easily lead to moisture damage to internal electronic compartments, gas sensors, batteries, and other components; limited resistance to acid and alkali and sewage corrosion, and easy aging and pulverization with long-term use; thermal conductivity and air permeability are not compatible with the working requirements of sensors, which can easily lead to sensor temperature drift and false alarms; and they do not have explosion-proof and flame-retardant properties, making them unsuitable for dangerous scenarios such as gas wells; and their fatigue life under heavy loads is short, only between 15 and 30 years.

[0003] To address the aforementioned issues, it is urgent to optimize and improve the composition of rock-based composite materials to overcome their performance shortcomings and make them suitable for the special application requirements of rock-based multi-gas detection smart well covers. Summary of the Invention

[0004] To address the aforementioned issues, this application proposes a smart rock-based composite manhole cover with multi-gas detection. The aim is to overcome the performance deficiencies of existing ordinary rock-based composite materials. Through component blending and modification, it achieves comprehensive performance characteristics including high strength, low water absorption, hydrophobicity and breathability, explosion-proof and flame-retardant properties, aging resistance, corrosion resistance, and compatibility with sensor operating requirements. Simultaneously, it provides specific and feasible formulation ratios, preparation processes, and performance verification data, offering technical support for the mass production and patent protection of smart manhole covers.

[0005] A smart rock-based composite manhole cover with multi-gas detection includes a detection breathing layer, a micro-protective chamber layer, a smart core sealing layer, and a load-bearing and energy harvesting layer. The detection breathing layer includes a bottom protective layer and a gas collection area. The gas collection area is located in the center of the bottom protective layer and has several gas collection holes. The micro-protective chamber is positioned above the gas collection area of ​​the micro-protective chamber and includes a ceramic cavity and a primary rock base filling layer. The intelligent core sealing layer, located above the micro-protective cabin layer, includes a microcontroller, a wireless communication module, a rechargeable battery pack, and a secondary rock base filling layer. The load-bearing and energy harvesting layer, located above the intelligent core sealing layer, includes a piezoelectric energy harvesting module, an energy management unit, and a rock foundation load-bearing layer.

[0006] Preferably, the ceramic cavity is embedded inside the primary bedrock filling layer; The bottom of the ceramic cavity is provided with an opening, and the opening corresponds one-to-one with the gas collection hole; The inner surface of the ceramic cavity is coated with a moisture-absorbing material; The ceramic cavity contains multiple gas sensors, which are positioned directly opposite the gas collection port. A waterproof and breathable membrane is provided between the ceramic cavity and the gas collection hole.

[0007] Preferably, the microcontroller is embedded in the center of the secondary bedrock filling layer; The wireless communication module and the rechargeable battery pack are respectively located on both sides of the microcontroller and embedded in the secondary rock bed filling layer.

[0008] Preferably, the piezoelectric energy harvesting module includes a plurality of piezoelectric energy harvesters; The piezoelectric energy harvester is embedded in the rock foundation bearing layer in a matrix manner; The energy management unit is located between the intelligent core sealing layer and the load-bearing and energy collection layer. The energy management unit integrates rectification, voltage regulation, and intelligent charging management circuits.

[0009] Preferably, the piezoelectric energy harvester is connected vertically downward to the energy management unit via a pre-embedded flexible cable; The rechargeable battery pack is connected to the energy management unit via a flexible cable; The microcontroller is connected to the multi-gas sensor and energy management unit via a short cable.

[0010] Preferably, the bottom protective layer, the primary rock base filling layer, the secondary rock base filling layer, and the rock base load-bearing layer are prepared using modified rock base composite materials; The modified rock-based composite material comprises the following components by mass percentage: Rock-based composite aggregates: 58%-73%; Reinforcing fiber 11%-17%; Resin matrix 11.5%-16%; Functional fillers: 4.3%-7.5%; Additives: 1.7%-2.8%.

[0011] Preferably, the rock-based composite aggregate comprises the following components by mass percentage: Basalt powder (800-1200 mesh) 35%-40%, quartzite powder (600-800 mesh) 15%-20%, hollow ceramic microspheres (particle size 5-10μm) 5%-8%, tailings rock powder (600-800 mesh) 3%-5%.

[0012] Preferably, the reinforcing fiber comprises, by weight percentage: 8%-12% continuous basalt fiber (10-15 μm in diameter), 2%-3% carbon fiber (chopped, 3-5 mm in length), and 1%-2% polypropylene coarse fiber (5-8 mm in length); The resin matrix comprises, by weight percentage, the following components: 8%-10% vinyl ester resin, 3%-5% modified epoxy resin E-44, and 0.5%-1% organosilicon modifier KH-550.

[0013] Preferably, the functional filler comprises, by mass percentage, the following components: 1%-2% PTFE micro powder (particle size 1-3 μm), 1%-2% nano-silica (particle size 50-100 nm), 0.3%-0.5% graphene (monolayer, particle size 5-10 μm), and 2%-3% halogen-free flame retardant; The halogen-free flame retardant is a mixture of aluminum hydroxide and phosphorus-nitrogen flame retardant in a mass ratio of 1:1; The additives, by mass percentage, comprise the following components: silane coupling agent (KH-560) 0.5%-1%, ultraviolet absorber (UV-327) 0.2%-0.3%, antioxidant (1010) 0.2%-0.3%, and curing agent (methyl ethyl ketone peroxide) 0.8%-1.2%.

[0014] Preferably, the preparation method of the rock-based multi-gas detection intelligent rock-based composite manhole cover includes the following steps: S1. Place basalt powder, quartzite powder, and tailings powder in a drying oven and dry at 105-110℃ for 2-3 hours to remove moisture; cut continuous basalt fiber into short fibers with a length of 10-15mm, and mix them evenly with carbon fiber and polypropylene coarse fiber for later use; place hollow ceramic microspheres, PTFE micro powder, nano silica, graphene, and halogen-free flame retardant in a high-speed mixer and stir at low speed for 5-10 minutes until evenly mixed for later use. S2. Place the pretreated rock-based composite aggregate into a high-speed mixer, adjust the speed to 800-1000 r / min, add silane coupling agent, stir for 15-20 minutes to make the coupling agent evenly coat the surface of the aggregate, improve the bonding force with the resin, and then take it out and cool it to room temperature for later use. S3. Place the vinyl ester resin and modified epoxy resin into a reaction vessel and stir at 60-70℃ for 30-40 minutes at a speed of 500-600 r / min; add the organosilicon modifier and continue stirring for 20-30 minutes; then add the ultraviolet absorber and antioxidant and stir for 10-15 minutes to obtain the modified resin matrix for later use. S4. Place the modified rock-based composite aggregate, reinforcing fiber mixture, and functional filler mixture into a high-speed mixer, adjust the speed to 1200-1500 r / min, and stir for 20-30 minutes until uniformly mixed. Then slowly add the modified resin matrix and continue stirring for 15-20 minutes to ensure the resin evenly coats the surface of the aggregate and fibers. Finally, add the curing agent and stir at low speed for 5-8 minutes to obtain the composite material mixture. S5. Inject the composite material mixture into a special mold for smart manhole covers, and use a vibration molding process with a vibration frequency of 2000-2500 r / min and a vibration time of 5-8 minutes to remove air bubbles from the mixture; then place it in a constant temperature curing oven and cure it at 80-90℃ for 2-3 hours, then raise the temperature to 120-130℃ and keep it at that temperature for 1-2 hours. S6. Remove the solidified manhole cover from the mold and remove burrs and sharp edges; process the gas collection micropores at the bottom of the manhole cover; finally, grind and polish the surface of the manhole cover to obtain the finished modified rock-based composite smart manhole cover.

[0015] In summary, the intelligent rock-based composite manhole cover with multi-gas detection based on rock, as described in this invention, has the following advantages compared to traditional technologies: 1. Possesses comprehensive properties such as high strength, low water absorption, high toughness, corrosion resistance, aging resistance, explosion-proof and flame retardant properties, and hydrophobic and breathable properties, fully adapting to the usage requirements of rock-based multi-gas detection smart manhole covers. It can effectively protect internal sensors, electronic components, batteries and other parts, ensuring long-term stable operation of the manhole cover. 2. Designed with special functional fillers to meet the specific needs of smart manhole covers, achieving integrated hydrophobicity and air permeability, ensuring accurate gas sensor detection, and meeting the personalized needs of different scenarios (gas wells, sewage wells), with a wide range of applications; 3. The preparation process is simple, the parameters of each step are clear, no special equipment is required, it is suitable for mass production, and can effectively reduce production costs and improve production efficiency.

[0016] The technical method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 A schematic diagram of the overall design of a smart rock-based composite manhole cover with multi-gas detection. Figure 2 A schematic diagram of the bottom of the ceramic cavity and the waterproof and breathable membrane; Figure 3 Top view of the load-bearing and energy harvesting layer; Figure 4 This is a flowchart illustrating the manufacturing process of a smart rock-based composite manhole cover with multi-gas detection.

[0018] Figure Labels 1. Breathing layer; 11. Bottom protective layer; 12. Gas collection area; 121. Gas collection port; 2. Miniature protective chamber layer; 21. Ceramic cavity; 211. Opening; 212. Multi-gas sensor; 22. Primary rock base filling layer; 3. Intelligent core sealing layer; 31. Microcontroller; 32. Wireless communication module; 33. Rechargeable battery pack; 34. Secondary rock base filling layer; 4. Load-bearing and energy harvesting layer; 41. Piezoelectric energy harvesting module; 411. Piezoelectric energy harvester; 42. Energy management unit; 43. Rock base load-bearing layer; 5. Waterproof and breathable membrane. Detailed Implementation

[0019] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0020] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0021] Techniques, systems, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the instruction manual.

[0022] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0024] Example 1 A smart rock-based composite manhole cover with multi-gas detection, such as Figure 1-3 As shown, the detection includes the breathing layer 1 (approximately 15% thick) which is in direct contact with the underground environment, located at the bottom of the manhole cover; Miniature protective cabin layer 2, intelligent core sealing layer 3, and load-bearing and energy harvesting layer 4; The detection breathing layer 1 includes a bottom protective layer 11 and a gas collection area 12. The gas collection area 12 is located in the center of the bottom protective layer 11. The gas collection area 12 is provided with several gas collection holes 121. These gas collection holes 121 have a very small diameter (about 1-2 mm) and are the only channel for downhole gas to enter the inside of the well cover. The area around the micropores can be locally thickened to prevent stress concentration from causing cracks.

[0025] The micro protective chamber layer 2 is located above the gas collection area 12 of the micro protective chamber layer 2, and includes a ceramic cavity 21 and a primary rock base filling layer 22; The ceramic cavity 21 can also be replaced with a micro-cavity (approximately 30mm × 30mm × 15mm) made of high-strength engineering plastic. During the casting of the manhole cover, it is precisely placed in the mold and then tightly wrapped by the rock base material.

[0026] This cavity can effectively disperse the huge mechanical load borne by the rock-based material through the cabin structure, and the stress transmitted to the sensor is negligible.

[0027] Furthermore, the ceramic cavity 21 is embedded inside the primary bedrock filling layer 22; The bottom of the ceramic cavity 21 is provided with an opening 211, which corresponds one-to-one with the gas collection port 121. The inner surface of the ceramic cavity 21 is coated with a moisture-absorbing material to maintain a constant microenvironment; A multi-gas sensor 212 is fixed inside the ceramic cavity 21, and the multi-gas sensor 212 faces the gas collection port 121. A waterproof and breathable membrane 5 is provided between the ceramic cavity 21 and the gas collection port 121. Downhole gas must pass through this membrane to meet the sensor, while liquid water and dust are completely blocked.

[0028] The intelligent core sealing layer 3 (approximately 35% thick) is located above the micro protective cabin layer 2 and includes a microcontroller 31, a wireless communication module 32, a rechargeable battery pack 33, and a secondary rock base filling layer 34. Furthermore, the microcontroller 31 (STM32 series microcontroller 31) is embedded in the center of the secondary rock bed filling layer 34; The wireless communication module 32 (in various forms such as Cat.1, NB-IoT, LoRawan) and the rechargeable battery pack 33 (high-performance lithium battery pack) are respectively located on both sides of the microcontroller 31 and embedded in the secondary rock base filling layer 34.

[0029] The NB-IoT wireless communication module 32 is positioned near the edge to ensure that the signal can penetrate the rock-based material and communicate smoothly with the cloud.

[0030] A high-performance lithium battery pack is symmetrically distributed on the other side, acting as a counterweight to maintain the mechanical balance of the manhole cover. The battery is connected to the energy management unit 42 above via a flexible cable.

[0031] The load-bearing and energy harvesting layer 4 (approximately 25% thick) is located above the intelligent core sealing layer 3 and includes a piezoelectric energy harvesting module 41, an energy management unit 42, and a rock foundation load-bearing layer 43.

[0032] Furthermore, the piezoelectric energy harvesting module 41 includes a plurality of piezoelectric energy harvesters 411; The piezoelectric energy harvester 411 is embedded in the rock foundation bearing layer 43 in a matrix manner. It can be selected as a cymbal structure or a stacked structure, which can efficiently convert mechanical energy into electrical energy when subjected to rolling.

[0033] The energy management unit 42 is located between the intelligent core sealing layer 3 and the load-bearing and energy harvesting layer 4; The energy management unit 42 integrates rectification, voltage regulation, and intelligent charging management circuitry. It converts the chaotic alternating current generated by the piezoelectric element into stable direct current and intelligently charges the rechargeable battery pack 33 in the third layer. Simultaneously, it monitors battery status and provides overcharge and over-discharge protection. It is a highly integrated and modular standard solution with a large number of mature commercial chips available for selection.

[0034] Furthermore, the piezoelectric energy harvester 411 is vertically connected downward to the energy management unit 42 via a pre-embedded flexible cable; The rechargeable battery pack 33 is connected to the energy management unit 42 via a flexible cable; The microcontroller 31 is connected to the multi-gas sensor 212 and the energy management unit 42 via a short cable.

[0035] In summary, when a vehicle runs over a manhole cover, the entire system's collaborative operation includes: Energy harvesting: The piezoelectric energy harvester 411 at the top generates electrical energy instantaneously, which is transmitted to the energy management unit 42 via cable, and the latter begins to charge the battery pack.

[0036] Gas sensing: Downhole gas passes through the bottom collection micropores, through the waterproof and breathable membrane 5, into the micro protective chamber, and is accurately captured by the gas sensor.

[0037] Data processing: The microcontroller 31 reads the sensor data and processes it using power supplied by the battery pack.

[0038] Information Upload: The processed data is sent to the cloud monitoring platform via the wireless communication module 32.

[0039] Example 2 This embodiment mentions a rock-based multi-gas detection intelligent rock-based composite manhole cover. The modified rock-based composite material, by mass percentage, comprises the following components: Basalt powder (1000 mesh) 38%, quartzite powder (700 mesh) 18%, hollow ceramic microspheres (8μm particle size) 6%, tailings rock powder (700 mesh) 4%, continuous basalt fiber (12μm diameter) 10%, carbon fiber (chopped, 4mm) 2.5%, polypropylene coarse fiber (6mm) 1.5%, vinyl ester resin 9%, modified epoxy resin (E-44) 4%, organosilicon modifier (KH-550) 0 0.8%, PTFE micro powder (2μm) 1.5%, nano silica (80nm) 1.5%, graphene (single layer, 8μm) 0.4%, halogen-free flame retardant (aluminum hydroxide + phosphorus nitrogen flame retardant = 1:1) 2.5%, silane coupling agent (KH-560) 0.8%, ultraviolet absorber (UV-327) 0.25%, antioxidant (1010) 0.25%, curing agent (methyl ethyl ketone peroxide) 1.0%.

[0040] like Figure 4 As shown, the preparation method is as follows: Raw material pretreatment: Basalt powder, quartzite powder, and tailings rock powder are placed in a drying oven and dried at 108℃ for 2.5 hours; continuous basalt fibers are cut into 12mm lengths and mixed evenly with carbon fiber and polypropylene coarse fiber; hollow ceramic microspheres, PTFE micro powder, nano silica, graphene, and halogen-free flame retardant are placed in a high-speed mixer and stirred at low speed for 8 minutes until evenly mixed.

[0041] Aggregate surface modification: The pretreated rock-based composite aggregate is placed in a high-speed mixer at 900 r / min, a silane coupling agent is added, and the mixture is stirred for 18 minutes and then cooled to room temperature for later use.

[0042] Resin matrix modification: Vinyl ester resin and modified epoxy resin are placed in a reactor and stirred at 65°C for 35 minutes at a speed of 550 r / min; an organosilicon modifier is added and stirring is continued for 25 minutes; an ultraviolet absorber and an antioxidant are added and stirred for 12 minutes to obtain the modified resin matrix.

[0043] Mixing and stirring: Put the modified aggregate, reinforcing fiber mixture, and functional filler mixture into a high-speed mixer and stir for 25 minutes at a speed of 1300 r / min; add the modified resin matrix and continue stirring for 18 minutes; add the curing agent and stir at low speed for 6 minutes to obtain the mixture.

[0044] Molding and casting: Inject the mixture into the mold, install the pre-embedded parts, and vibrate to form (2200r / min, 6 minutes); place it in a constant temperature curing oven, cure at 85℃ for 2.5 hours, then raise the temperature to 125℃ and keep it at that temperature for 1.5 hours to complete the secondary curing.

[0045] Post-processing: demolding, deburring, and machining of gas collection micropores ( The micropores are thickened by 2.5mm around the micropores (1.5mm), then polished to obtain the finished product.

[0046] Testing showed that the modified rock-based composite material prepared in this embodiment had a compressive strength of 265 MPa, a water absorption rate of 0.025%, and an impact strength of 190 kJ / m². 2 The acid and alkali corrosion resistance has a mass change rate of ±0.4%, flame retardant rating V-0, explosion-proof rating Exd IIC T6, strength decrease of 4% after 1000h of UV aging, and air permeability of 58mL / (cm). 2 ·h), fully meeting the usage requirements of rock-based multi-gas detection smart manhole covers.

[0047] Example 2 (for gas wells only) This embodiment mentions a rock-based multi-gas detection intelligent rock-based composite manhole cover. The modified rock-based composite material, by mass percentage, comprises the following components: Basalt powder (1200 mesh) 40%, quartzite powder (800 mesh) 15%, hollow ceramic microspheres (10μm particle size) 5%, tailings rock powder (800 mesh) 3%, continuous basalt fiber (15μm diameter) 12%, carbon fiber (chopped, 5mm) 3%, polypropylene coarse fiber (8mm) 2%, vinyl ester resin 8%, modified epoxy resin (E-44) 3%, organosilicon modifier (KH-550) 0.5%, PTFE micro powder (3μm) 2%, nano silica (100nm) 2%, graphene (single layer, 10μm) 0.5%, halogen-free flame retardant (aluminum hydroxide + phosphorus nitrogen flame retardant = 1:1) 3%, silane coupling agent (KH-560) 1.0%, ultraviolet absorber (UV-327) 0.3%, antioxidant (1010) 0.3%, curing agent (methyl ethyl ketone peroxide) 1.2%.

[0048] The preparation method is basically the same as in Example 1, except that the sealing performance of the mold is increased during molding and casting to ensure accurate molding of the explosion-proof cavity. Testing showed that the composite material prepared in this example achieves an explosion-proof rating of Exd IIC T6, a flame retardant rating of V-0, and excellent antistatic properties, making it suitable for use in gas well scenarios.

[0049] Example 3 (for sewage wells only) A modified rock-based composite material for use in a rock-based multi-gas detection smart well cover, comprising the following components by mass percentage: Basalt powder (800 mesh) 35%, quartzite powder (600 mesh) 20%, hollow ceramic microspheres (5μm particle size) 8%, tailings rock powder (600 mesh) 5%, continuous basalt fiber (10μm diameter) 8%, carbon fiber (chopped, 3mm) 2%, polypropylene coarse fiber (5mm) 1%, vinyl ester resin 10%, modified epoxy resin (E-44) 5%, organosilicon modifier (KH-550) 1.0%, PTFE micro powder (1μm) 1%, nano silica (50nm) 1%, graphene (single layer, 5μm) 0.3%, halogen-free flame retardant (aluminum hydroxide + phosphorus nitrogen flame retardant = 1:1) 2%, silane coupling agent (KH-560) 0.5%, ultraviolet absorber (UV-327) 0.2%, antioxidant (1010) 0.2%, curing agent (methyl ethyl ketone peroxide) 0.8%.

[0050] The preparation method is basically the same as that in Example 1. After testing, the composite material prepared in this example has a mass change rate of ±0.3% for acid and alkali corrosion resistance, a water absorption rate of 0.02%, and excellent aging resistance, making it suitable for use in highly corrosive environments such as sewage wells.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical methods of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical methods to deviate from the spirit and scope of the technical methods of the present invention.

Claims

1. A rock-based multi-gas detection intelligent rock-based composite well lid, characterized in that, This includes a detection breathing layer, a micro-protective chamber layer, an intelligent core sealing layer, and a load-bearing and energy harvesting layer; The detection breathing layer includes a bottom protective layer and a gas collection area. The gas collection area is located in the center of the bottom protective layer and has several gas collection holes. The micro-protective chamber is positioned above the gas collection area of ​​the micro-protective chamber and includes a ceramic cavity and a primary rock base filling layer; The intelligent core sealing layer, located above the micro protective cabin layer, includes a microcontroller, a wireless communication module, a rechargeable battery pack, and a secondary rock base filling layer. The load-bearing and energy harvesting layer, located above the intelligent core sealing layer, includes a piezoelectric energy harvesting module, an energy management unit, and a rock foundation load-bearing layer.

2. A rock-based multi-gas detection intelligent rock-based composite well lid according to claim 1, characterized in that, The ceramic cavity is embedded inside the primary bedrock filling layer; The bottom of the ceramic cavity is provided with an opening, and the opening corresponds one-to-one with the gas collection hole; The inner surface of the ceramic cavity is coated with a moisture-absorbing material; The ceramic cavity is equipped with multiple gas sensors, which are positioned directly opposite the gas collection port. A waterproof and breathable membrane is provided between the ceramic cavity and the gas collection hole.

3. The intelligent rock-based composite manhole cover with multi-gas detection according to claim 2, characterized in that, The microcontroller is embedded in the center of the secondary rock bed filling layer; The wireless communication module and the rechargeable battery pack are respectively located on both sides of the microcontroller and embedded in the secondary rock bed filling layer.

4. The intelligent rock-based composite manhole cover with multi-gas detection according to claim 3, characterized in that, The piezoelectric energy harvesting module includes several piezoelectric energy harvesters; The piezoelectric energy harvester is embedded in the rock foundation bearing layer in a matrix manner; The energy management unit is located between the intelligent core sealing layer and the load-bearing and energy collection layer. The energy management unit integrates rectification, voltage regulation, and intelligent charging management circuits.

5. The intelligent rock-based composite manhole cover with multi-gas detection according to claim 4, characterized in that, The piezoelectric energy harvester is connected vertically downward to the energy management unit via a pre-embedded flexible cable; The rechargeable battery pack is connected to the energy management unit via a flexible cable; The microcontroller is connected to the multi-gas sensor and energy management unit via a short cable.

6. The intelligent rock-based composite manhole cover with multi-gas detection according to claim 5, characterized in that, The bottom protective layer, primary rock base filling layer, secondary rock base filling layer and rock base load-bearing layer are prepared using modified rock base composite materials; The modified rock-based composite material comprises the following components by mass percentage: Rock-based composite aggregates: 58%-73%; Reinforcing fiber 11%-17%; Resin matrix 11.5%-16%; Functional fillers: 4.3%-7.5%; Additives: 1.7%-2.8%.

7. The intelligent rock-based composite manhole cover with multi-gas detection according to claim 6, characterized in that, The rock-based composite aggregate comprises the following components by mass percentage: Basalt powder 35%-40%, quartzite powder 15%-20%, hollow ceramic microspheres 5%-8%, tailings rock powder 3%-5%.

8. The intelligent rock-based composite manhole cover with multi-gas detection according to claim 7, characterized in that, The reinforcing fiber comprises, by weight percentage, the following components: 8%-12% continuous basalt fiber, 2%-3% carbon fiber, and 1%-2% coarse polypropylene fiber; The resin matrix comprises, by weight percentage, the following components: 8%-10% vinyl ester resin, 3%-5% modified epoxy resin E-44, and 0.5%-1% organosilicon modifier KH-550.

9. A rock-based multi-gas detection intelligent rock-based composite manhole cover according to claim 8, characterized in that, The functional filler comprises, by weight percentage: 1%-2% PTFE micro powder, 1%-2% nano-silica, 0.3%-0.5% graphene, and 2%-3% halogen-free flame retardant; The halogen-free flame retardant is a mixture of aluminum hydroxide and phosphorus-nitrogen flame retardant in a mass ratio of 1:1; The additives, by mass percentage, comprise the following components: 0.5%-1% silane coupling agent, 0.2%-0.3% ultraviolet absorber, 0.2%-0.3% antioxidant, and 0.8%-1.2% curing agent.

10. A rock-based multi-gas detection intelligent rock-based composite manhole cover according to claim 9, characterized in that, The preparation method of the intelligent rock-based composite manhole cover with multi-gas detection includes the following steps: S1. Place basalt powder, quartzite powder, and tailings powder in a drying oven and dry at 105-110℃ for 2-3 hours to remove moisture; cut continuous basalt fiber into short fibers with a length of 10-15mm, and mix them evenly with carbon fiber and polypropylene coarse fiber, set aside; place hollow ceramic microspheres, PTFE micro powder, nano silica, graphene, and halogen-free flame retardant in a high-speed mixer, stir at low speed for 5-10 minutes, mix evenly, set aside; S2. Place the pretreated rock-based composite aggregate into a high-speed mixer, adjust the speed to 800-1000 r / min, add silane coupling agent, stir for 15-20 minutes to make the coupling agent evenly coat the surface of the aggregate, improve the bonding force with the resin, and then take it out and cool it to room temperature for later use. S3. Place the vinyl ester resin and modified epoxy resin into a reaction vessel and stir at 60-70℃ for 30-40 minutes at a speed of 500-600 r / min; add the organosilicon modifier and continue stirring for 20-30 minutes; then add the ultraviolet absorber and antioxidant and stir for 10-15 minutes to obtain the modified resin matrix for later use. S4. Place the modified rock-based composite aggregate, reinforcing fiber mixture, and functional filler mixture into a high-speed mixer, adjust the speed to 1200-1500 r / min, and stir for 20-30 minutes until uniformly mixed. Then slowly add the modified resin matrix and continue stirring for 15-20 minutes to ensure the resin evenly coats the surface of the aggregate and fibers. Finally, add the curing agent and stir at low speed for 5-8 minutes to obtain the composite material mixture. S5. Inject the composite material mixture into a special mold for smart manhole covers, and use a vibration molding process with a vibration frequency of 2000-2500 r / min and a vibration time of 5-8 minutes to remove air bubbles from the mixture; then place it in a constant temperature curing oven and cure it at 80-90℃ for 2-3 hours, then raise the temperature to 120-130℃ and keep it at that temperature for 1-2 hours. S6. Remove the solidified manhole cover from the mold and remove burrs and sharp edges; process the gas collection micropores at the bottom of the manhole cover; finally, grind and polish the surface of the manhole cover to obtain the finished modified rock-based composite smart manhole cover.

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