CN108285569B - Built-in self-sensing geogrid structure and method - Google Patents
Built-in self-sensing geogrid structure and method Download PDFInfo
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- CN108285569B CN108285569B CN201810220815.9A CN201810220815A CN108285569B CN 108285569 B CN108285569 B CN 108285569B CN 201810220815 A CN201810220815 A CN 201810220815A CN 108285569 B CN108285569 B CN 108285569B
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Classifications
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
- C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
- C08L23/04—Homopolymers or copolymers of ethene
- C08L23/06—Polyethene
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
- G08B21/18—Status alarms
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/001—Conductive additives
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/014—Additives containing two or more different additives of the same subgroup in C08K
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
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- Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Civil Engineering (AREA)
- Soil Sciences (AREA)
- Agronomy & Crop Science (AREA)
- Business, Economics & Management (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Environmental & Geological Engineering (AREA)
- General Engineering & Computer Science (AREA)
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- Emergency Management (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
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Abstract
The invention discloses a built-in self-sensing geogrid structure and a method, which solve the problem of serious engineering casualty accidents in the prior art and have the beneficial effects of realizing on-line dynamic monitoring and safety early warning of reinforced soil, and the scheme is as follows: the utility model provides a built-in self-sensing geogrid structure, includes at least one first rib that constitutes by adding the polymer of conductive filler and at least two rows of thermoplastic polymer strips that are equipped with the wire constitute second rib, and the second rib is crisscross to be set up with first rib and is constituted the structure of multirow second rib and at least one row first rib, and the department of staggering adopts the hasp to connect, and the wire and the first rib contact setting of second rib, and the corresponding wire and the resistance detection equipment connection of two rows of wherein second ribs that stagger with same first rib.
Description
Technical Field
The invention relates to the field of civil engineering, in particular to a built-in self-sensing geogrid structure and a built-in self-sensing geogrid structure method.
Background
In recent years, along with large-scale construction of water conservancy and traffic infrastructure in China, particularly along with the extension of traffic networks to mountain areas, high and large reinforced soil structures (high and large retaining walls, roadbeds and the like with the height of more than 20 m) are increasing. Under the coupling effect of disaster factors such as environmental erosion, long-term effect of material aging and load, fatigue effect, abrupt change effect and the like, disasters such as deformation, cracking, even collapse and the like of a high reinforced soil structure occur, and great loss is brought to life and property of people. In order to reduce the occurrence of disasters, in the design of a high reinforced soil structure, engineering technicians often adopt geogrids to carry out reinforcement and consolidation treatment on soil bodies, but the occurrence of serious engineering casualties still cannot be avoided. In order to realize the stress monitoring and overload protection of the high and large reinforced soil structure, the students at home and abroad research and develop the geogrid with the sensing characteristic, and the stress change of the geogrid can be directly converted into an electric signal and output.
However, the existing sensing type geogrid often obtains certain conductive performance by adding a large amount of carbon black into polyethylene at the cost of reducing the strength of the geogrid, so that the tensile strength, the toughness and the sensitivity of the geogrid are low, the repeatability of the sensing performance under a cyclic load is poor, and the requirements of actual engineering cannot be met.
Therefore, new research designs for a built-in self-sensing geogrid structure are needed.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a built-in self-sensing geogrid structure, which has the advantages of stronger built-in and occlusion effects with soil, high specific strength, high specific modulus, corrosion resistance, fatigue resistance, creep resistance, more sensitive self-sensing characteristics, more stable strain-resistance repeatability and the like, and can be used as a structural material for bearing load and a functional material for timely repairing.
The concrete scheme of the embedded self-sensing geogrid structure is as follows:
the utility model provides a built-in self-sensing geogrid structure, includes at least one first rib that constitutes by adding the polymer of conductive filler and at least two rows of thermoplastic polymer strips that are equipped with the wire constitute second rib, and the second rib is crisscross to be set up with first rib and is constituted the structure of multirow second rib and at least one row first rib, and the department of staggering adopts the hasp to connect, and the wire and the first rib contact setting of second rib, and the corresponding wire and the resistance detection equipment connection of two rows of wherein second ribs that stagger with same first rib.
In the geogrid structure, the first rib is used as an electrical element for sensing the structural change of the soil body, the second rib is used as a circuit element for collecting electrical signals, the lock catch is used as a connecting element for fixedly connecting the first rib and the second rib, the service life of the geogrid is effectively prolonged by adopting the polymer strips, and when the geogrid is deformed, the resistance change of the first rib is detected through the measuring points at the joint of the first rib and the second rib, so that the online dynamic monitoring and the safety early warning of the reinforced soil body in the whole life cycle can be realized.
Further, to ensure uniformity of mechanical parameters of each of the splice units in the geogrid, the first rib material includes chopped carbon fiber, carbon fiber powder, superconducting carbon black, graphite, a silane coupling agent, a titanate coupling agent, ethylene Propylene Diene Monomer (EPDM), polyethylene, and polypropylene.
Further, the second rib material comprises carbon black, polyethylene, polypropylene and ethylene propylene diene monomer; the thermoplastic polymer strip is internally carved with an open slot for arranging a wire.
Further, the wires in the plurality of rows of the second ribs are arranged at different heights;
Or the first ribs are longitudinally arranged, the second ribs are transversely arranged, and the second ribs are arranged on the surface of the first ribs at the staggered positions.
Further, the lock catch comprises carbon black, polyethylene, polypropylene and ethylene propylene diene monomer; the second rib, the first rib and the lock catch are all made of a double-component polymer system with polyethylene and polypropylene as matrixes, and a set amount of solubilizing agent EPDM is doped to improve the compatibility of the two; such a polymer system: on one hand, the polypropylene has excellent mechanical property and durability, and overcomes the defects of low strength of polyethylene and poor aging resistance of polypropylene; on the other hand, the self-sensing conductive film is applied to the first rib with the self-sensing characteristic, can form a double-seepage conductive network structure, can effectively reduce the seepage threshold value of a system, and achieves the aim of reducing the resistivity.
Or the lock catch is connected with one end of the second rib or the first rib connecting side, the other end of the lacing wire belt is provided with a lacing wire hoop, the lacing wire hoop is arranged around the first rib or the second rib, the lacing wire hoop is vertically arranged with the first rib or the second rib, the first rib and the second rib can be prevented from being separated through the arrangement of the lacing wire hoop and the lacing wire strip, and the lacing wire hoop and the lock catch are formed by injection molding together.
Further, the mass fraction of each material in the first rib is as follows: 45-54% of polyethylene and 15-18% of polypropylene; 2-4% of chopped carbon fiber, 4-8% of carbon fiber powder and 4-6% of superconducting carbon black; 2-5% of graphite, 5-10% of silane coupling agent and 5-10% of titanate coupling agent; the ethylene propylene diene monomer is 6 to 12 percent.
The chopped carbon fiber is a filament with the length of 1mm and the diameter of 7um, and has the advantages of light weight, high strength, high modulus, corrosion resistance and outstanding conductive performance; the carbon fiber powder is a composite material filler with fine appearance, which is cuboid with the length of 30-50um and the diameter of 7um, has good conductive performance, fine shape, pure surface, large specific surface area and easy infiltration and uniform dispersion by resin, and is prepared by carrying out surface treatment, process grinding, microscopic screening and high-temperature drying on carbon fibers to obtain particles; the granularity of the superconducting carbon black in the microstructure is 33nm, the specific surface area is large, and the conductivity is excellent; the microscopic shape of the graphite is similar to spherical particles of 6-10um, and the graphite has good chemical stability, wear resistance and conductivity.
The conductive polymer composite material has typical percolation phenomenon, namely when the doping amount of the conductive phase is smaller than a critical value, the resistivity of the composite material does not change obviously along with the increase of the doping amount of the conductive phase; when the doping amount of the conductive phase is close to a critical value, the resistivity of the composite material is rapidly reduced along with the increase of the conductive phase, and can be reduced by several orders of magnitude, wherein the critical value is called a percolation threshold; however, as the amount of conductive phase doping continues to increase beyond the percolation threshold, the resistivity changes with the amount of doping, again, to slow down. The related studies show that the percolation regions of different conductive phases are different, and the doping amount required when the conductive phases form a conductive network is different due to the size and morphology of the conductive phases. In the first rib material, four conductive phases are used in a multi-doping way, and the prepared functional polymer has the advantages of single conductive phase preparation by utilizing the different size and morphology characteristics of different conductive phases, and meanwhile, the synergistic effect among conductive fillers is beneficial to forming a stable conductive network, so that the doping amount required by a percolation threshold is reduced. The fibrous chopped carbon fibers are mutually overlapped to form a conductive network to provide remote conduction; the granular carbon fiber powder, the superconducting carbon black and the graphite not only provide short-range conduction, but also can activate contact among the chopped carbon fibers through bridging action of the conductive particles, so that the conductivity of the composite material is increased, and the sensitivity and stability of the strain-resistance of the conductive polymer composite material are improved.
In addition, the inner surface of the lock catch is provided with textures and provided with grooves, so that the embedding and engaging effects with soil bodies are improved.
The preparation method of the embedded self-sensing geogrid structure comprises the following steps:
1) Preparing the first rib and the second rib respectively;
2) And splicing and connecting the first rib and the second rib.
Further, the preparation process of the first rib is as follows:
1-1) taking chopped carbon fiber, carbon fiber powder, super-conductive carbon black and graphite as conductive fillers, uniformly mixing according to a set mass fraction, placing the mixture into mixed acid of concentrated sulfuric acid/concentrated nitric acid, adding industrial alcohol, and treating for a set time at a set temperature;
1-2) diluting the mixed solution obtained in the step 1) with clear water with a set volume, carrying out vacuum suction filtration with a microfiltration membrane, repeatedly diluting and carrying out suction filtration for many times until the filtrate becomes neutral, and drying at a set temperature for later use;
1-3) placing the conductive filler after acidification treatment, a silane coupling agent, a titanate coupling agent, ethylene propylene diene monomer rubber, polyethylene and polypropylene into a high-speed mixer for uniform mixing;
1-4) placing the uniform mixture into a double-screw extruder for extrusion granulation for a plurality of times;
1-5) putting the granules into an injection molding machine for melting, and injecting into conductive polymer strips with required sizes;
1-6) coating a layer of conductive silver adhesive at equal intervals according to the size of the required geogrid, attaching a copper foil type conductive adhesive tape, coating the conductive silver adhesive between the polymer strips and the copper foil type conductive adhesive tape, ensuring that the polymer strips and the copper foil type conductive adhesive tape are always in full contact, forming a good conductive coating, and attaching the copper foil type conductive adhesive tape on the surface of the conductive polymer strips to form the electrode.
Further, the second rib is prepared as follows:
2-1) carrying out melt blending injection molding on carbon black, polyethylene, polypropylene and ethylene propylene diene monomer according to a set mass fraction to obtain slices with required size; wherein the mass fraction of polyethylene is 65-75%, the mass fraction of polypropylene is 15-25%, the mass fraction of ethylene propylene diene monomer is 4-7%, and the mass fraction of carbon black is 3-6%;
2-2) positioning and marking a built-in wire path on the surface of the rack;
2-3) grooving the wire according to the marked wire path by using a grooving machine, wherein the groove depth is required to be 2-4 times of the diameter of the wire, and the groove depth is less than or equal to 1/3 of the thickness of the second rib;
2-4) firmly welding the lead and the copper circuit measuring point, embedding the lead and the copper circuit measuring point into the groove, and dripping glue for fixing;
2-5) filling and sealing the groove by using a thermoplastic machine, wherein the copper circuit measuring point is exposed;
2-6) uniformly coating conductive silver adhesive around the copper circuit measuring point, and timely pasting a copper foil type conductive adhesive tape.
Further, the specific steps of the step 2) are as follows:
3-1) adding carbon black, polyethylene, polypropylene and ethylene propylene diene monomer (wherein the mass fraction of the polyethylene is 65-75%, the mass fraction of the polypropylene is 15-25%, the mass fraction of the ethylene propylene diene monomer is 4-7%, and the mass fraction of the carbon black is 3-6%) into a thermoplastic machine for melting for later use;
3-2) coating a layer of conductive silver glue on the first rib and the second rib, arranging conductive copper foils at the staggered position of the first rib and the second rib, splicing and aligning the conductive copper foils of the first rib and the second rib to communicate a circuit, and carrying out early consolidation treatment by using glue;
3-3) sealing and waterproofing the joint of the first rib and the second rib;
3-4) performing post-consolidation treatment on the joint of the first rib and the second rib by using a thermoplastic machine to form a thermoplastic lock catch, and completing the joint.
Compared with the prior art, the invention has the beneficial effects that:
1) The structure of the invention has the advantages of high specific strength, high specific modulus, corrosion resistance, fatigue resistance, creep resistance, more sensitive self-sensing characteristic, more stable strain-resistance repeatability and the like.
2) The invention can realize the on-line dynamic monitoring and the safety early warning of the reinforced soil body in the whole life cycle through the detection of the first rib resistance.
3) The invention can ensure the connection tightness of the first rib and the second rib through the arrangement of the lacing wire belt and the lacing wire hoop.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application.
FIG. 1 is a schematic view of an appearance of a built-in self-sensing geogrid;
FIG. 2 is a schematic view of a first rib of a built-in self-sensing geogrid structure;
FIG. 3 is a schematic view of a second rib of a built-in self-sensing geogrid structure;
FIG. 4 is a schematic illustration of a lock catch of a built-in self-sensing geogrid structure;
FIG. 5 is a schematic diagram of a partial circuit of a built-in self-sensing geogrid structure;
In the figure: 1-first rib, 2-second rib, 3-thermoplastic latch, 4-integrated bus, 5-copper foil conductive tape, 6-electrode measuring point, 7-built-in copper wire, 8-central latch, 9-lacing wire, 10-lacing wire hoop and 11-circuit lead.
Detailed Description
It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the application. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
As described in the background art, the present application provides a built-in self-sensing geogrid structure to solve the above technical problems.
In an exemplary embodiment of the present application, as shown in fig. 1 and 2, a built-in self-sensing geogrid structure includes at least one row of first ribs made of polymer added with conductive filler and at least two rows of second ribs made of thermoplastic polymer strips with wires inside, the second ribs are staggered with the first ribs to form a structure of a plurality of rows of second ribs and at least one row of first ribs, the staggered positions are connected by using lock catches, the wires of the second ribs are contacted with the first ribs, corresponding wires of two rows of second ribs staggered with the same first ribs are connected with resistance detection equipment, and the geogrid structure forms a multi-row and multi-column structure.
In the geogrid structure, the first rib is used as an electrical element for sensing structural change of soil, the second rib is used as a circuit element for collecting electrical signals, the lock catch is used as a connecting element for fixedly connecting the first rib and the second rib, the lock catch is connected with the resistance detection equipment through a wire, and the on-line dynamic monitoring of the reinforced soil is realized through the change of the resistance of the first rib, so that the complexity of a circuit is effectively reduced, and a simple and easily-measured circuit is formed.
In order to ensure the consistency of the mechanical parameters of each spliced unit in the geogrid, the first rib material comprises chopped carbon fiber, carbon fiber powder, superconducting carbon black, graphite, silane coupling agent, titanate coupling agent, ethylene Propylene Diene Monomer (EPDM), polyethylene and polypropylene.
The second rib material comprises carbon black, polyethylene, polypropylene and ethylene propylene diene monomer; the thermoplastic polymer strips are engraved with open grooves for the placement of the wires. The wires in the plurality of rows of the second ribs are arranged at different heights, and the plurality of wires form an integrated bus at the end side.
The lock catch comprises carbon black, polyethylene, polypropylene and ethylene propylene diene monomer; the second rib, the first rib and the lock catch are all made of a double-component polymer system with polyethylene and polypropylene as matrixes, and a set amount of solubilizing agent EPDM is doped to improve the compatibility of the two; such a polymer system: on one hand, the polypropylene has excellent mechanical property and durability, and overcomes the defects of low strength of polyethylene and poor aging resistance of polypropylene; on the other hand, the self-sensing conductive film is applied to the first rib with the self-sensing characteristic, can form a double-seepage conductive network structure, can effectively reduce the seepage threshold value of a system, and achieves the aim of reducing the resistivity.
The lock catch is connected with one end of the lacing wire belt at the connecting side of the second rib or the first rib, the lacing wire hoops which are perpendicular to the lacing wire belt are arranged at the other end of the lacing wire belt, the first rib is a longitudinal rib, and the second rib is a transverse rib. The lock catch is formed by thermoplastic stamping of a die, the longitudinal and transverse ribs are tightly sleeved, the locking force is strong, the sealing performance is good, the lock catch is a bulge node, and the surface of the lock catch is provided with textures and circular grooves, so that the embedding and meshing effects with soil bodies are improved; the lacing wire belt is in seamless connection with the central lock catch, and is bonded with the longitudinal second rib into a whole by strong glue, so that the lock catch can be prevented from sliding; the lacing wire hoop is in seamless connection with the lacing wire belt, and is bonded with the longitudinal second rib into a whole by strong glue, so that the loosening of the lacing wire belt can be prevented.
The mass fraction of each material in the first rib is as follows: 45-54% of polyethylene and 15-18% of polypropylene; 2-4% of chopped carbon fiber, 4-8% of carbon fiber powder and 4-6% of superconducting carbon black; 2-5% of graphite, 5-10% of silane coupling agent and 5-10% of titanate coupling agent; the ethylene propylene diene monomer is 6 to 12 percent.
The preparation method of the embedded self-sensing geogrid structure comprises the following steps:
1) Preparing the first rib and the second rib respectively;
2) And splicing and connecting the first rib and the second rib.
Further, the preparation process of the first rib is as follows:
1-1) taking chopped carbon fiber, carbon fiber powder, super-conductive carbon black and graphite as conductive fillers, uniformly mixing according to a set mass fraction, placing the mixture into mixed acid of concentrated sulfuric acid/concentrated nitric acid, adding industrial alcohol, and treating for 4 hours at 130 ℃; wherein, the volume ratio of the concentrated sulfuric acid to the concentrated nitric acid is 3:1;
1-2) diluting the mixed solution obtained in the step 1) by using clear water with a set volume, carrying out vacuum suction filtration by using a microfiltration membrane with the aperture of 0.2um, repeatedly diluting and carrying out suction filtration for many times until the filtrate becomes neutral, and drying at the temperature of 100 ℃ for later use;
1-3) placing the conductive filler after acidification treatment, a silane coupling agent, a titanate coupling agent, ethylene propylene diene monomer rubber, polyethylene and polypropylene into a high-speed mixer for uniform mixing;
1-4) placing the uniform mixture into a double-screw extruder for extrusion granulation for a plurality of times;
1-5) putting the granules into an injection molding machine for melting, and injecting into conductive polymer strips with required sizes;
1-6) coating a layer of conductive silver adhesive at equal intervals (namely, at the intersection of the longitudinal and transverse ribs) according to the size of the required geogrid, and attaching a copper foil type conductive adhesive tape.
In the preparation process, various polar groups exist on the surfaces of the conductive phase particles in the conductive filler to different degrees, such as: hydroxyl, carboxyl, lactone group and the like, the cohesive energy among particles is strong, the aggregate surface area of the particles is large, the particles are difficult to disperse and flocculate in a matrix material, and the compatibility of the conductive phase particles and the matrix material is affected. Therefore, through the arrangement of the steps 1-2) and 1-3), the surface activity, the specific surface area and the surface roughness of the conductive filler can be effectively increased; the latter may increase the compatibility of the conductive filler with the matrix material.
Further, the second rib is prepared as follows:
2-1) carrying out melt blending injection molding on carbon black, polyethylene, polypropylene and ethylene propylene diene monomer according to a set mass fraction to obtain slices with required size;
2-2) positioning and marking a built-in wire path on the surface of the rack, so that the phenomenon of short circuit caused by intertwining of copper wires in the second ribs is effectively avoided;
2-3) grooving the wire according to the marked wire path by using a grooving machine, wherein the groove depth is required to be 2-4 times of the diameter of the wire, and the groove depth is less than or equal to 1/3 of the thickness of the second rib;
2-4) firmly welding the lead and the copper circuit measuring point, embedding the lead and the copper circuit measuring point into the groove, and dripping glue for fixing;
2-5) filling and sealing the groove by using a thermoplastic machine, wherein the copper circuit measuring point is exposed;
2-6) uniformly coating conductive silver adhesive around the copper circuit measuring point, and timely pasting a copper foil type conductive adhesive tape.
Further, the specific steps of the step 2) are as follows:
3-1) adding carbon black, polyethylene, polypropylene and ethylene propylene diene monomer into a thermoplastic machine for melting for later use;
3-2) coating a layer of conductive silver adhesive on the first rib and the second rib, splicing and aligning the conductive copper foils of the first rib and the second rib to connect the circuit, and carrying out early consolidation treatment by using glue;
3-3) sealing and waterproofing the joint of the first rib and the second rib;
3-4) performing post-consolidation treatment on the joint of the first rib and the second rib by using a thermoplastic machine to form a thermoplastic lock catch, and completing the joint.
The first rib in the embedded self-sensing geogrid is used as an electrical element for sensing the soil body change, and the second rib is used as a circuit element for detecting the resistance change in the first rib, as shown in fig. 5. And the circuit lead in the second rib A, B, C is communicated with the resistance meter, so that the real-time on-line monitoring of the working state of the first rib can be realized. If the circuit leads L1, L2, L3 monitor the resistance change of the first rib E in real time, the leads L1, L2 monitor the resistance value between the circuit measuring points ①、④, and the leads L2, L3 monitor the resistance value between the circuit measuring points ④、⑦; the circuit leads M1, M2 and M3 monitor the resistance change of the first rib F in real time, the leads M1 and M2 monitor the resistance value between circuit measuring points ②、⑤, and the leads M2 and M3 monitor the resistance value between circuit measuring points ⑤、⑧; the circuit leads N1, N2, N3 monitor the resistance change of the first rib G in real time, the leads N1, N2 monitor the resistance value between the circuit measurement points ③、⑥, and the leads N2, N3 monitor the resistance value between the circuit measurement points ⑥、⑨.
In order to detect the strain-resistance sensitivity of the conductive polymer in the first rib, 250g of polyethylene, 80g of polypropylene, 15g of chopped carbon fiber, 30g of carbon fiber powder, 25g of superconducting carbon black, 15g of graphite, 25g of silane coupling agent and 25g of titanate coupling agent are taken, 35g of ethylene propylene diene monomer rubber is melt blended and injected into a dumbbell-shaped standard mechanical test piece, electrodes are added at two ends of a plurality of groups of conductive polymer test pieces, the test pieces are placed on a WDW-100 universal tester for axial stretching, the stretching speed is 1mm/min, and the resistance of the test pieces is synchronously measured by a direct current resistance meter. The acquired data are processed to obtain the relation between the relative change rate of the tensile resistance and the strain of the sample, the sensitivity coefficient is 1.956-2.432, the average value is 2.184, the effect is better than that of a foil-type resistance strain gauge with the common sensitivity of 2.000, and the measured tensile strength reaches 27.8MPa.
The embedded geogrid is used for a high reinforced soil structure, so that the real-time monitoring and the safety early warning of the reinforced soil body can be realized, and the occurrence of major engineering disasters is reduced. The strain-resistance characteristic of a conductive polymer, that is, the behavior in which the resistance of a conductive polymer increases in proportion to an increase in strain under tensile strain, is referred to as the elastic range. The strain-resistance characteristic of the conductive polymer can be used for realizing real-time monitoring of the working state of the grid, namely realizing on-line dynamic monitoring of the reinforced soil body by measuring the resistance change of the first rib:
Relationship between resistance change and deformation in the first rib:
ΔR＝k×Δl (1)
changing the formula (1) into a dimensionless relation:
First rib strain:
bringing the formula (3) into the formula (2), and performing formula conversion to obtain:
Wherein: Δr is the resistance change, R 0 is the initial resistance of the first rib, k is a dimensionless constant, Δl is the first rib elongation, l is the first rib initial length, and epsilon is the line strain of the first rib.
Therefore, the initial resistance value and the first rib elongation are measured by the structure in the present embodiment, so that the line strain of the first rib is obtained, and thus, the real-time monitoring of the operating state of the grille is obtained.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. The embedded self-sensing geogrid structure is characterized by comprising at least one row of first ribs formed by polymers added with conductive fillers and at least two rows of second ribs formed by thermoplastic polymer strips with wires arranged inside, wherein the second ribs and the first ribs are arranged in a staggered manner to form a structure of a plurality of rows of second ribs and at least one row of first ribs, the staggered positions are connected by adopting lock catches, the wires of the second ribs are arranged in contact with the first ribs, corresponding wires of two rows of second ribs staggered with the same first ribs are connected with resistance detection equipment, and the wires in a plurality of rows of second ribs are arranged at different heights;
The first ribs are longitudinally arranged, the second ribs are transversely arranged, the second ribs at the staggered positions are arranged on the surfaces of the first ribs, the first ribs are used as electrical elements for sensing structural changes of soil, and the second ribs are used as circuit elements for collecting electrical signals;
The lock catch is connected with one end of the lacing wire strap on the connecting side of the second rib or the first rib, the lacing wire strap is arranged on the other end of the lacing wire strap, and the lacing wire strap is arranged around the first rib or the second rib.
2. The embedded self-sensing geogrid structure according to claim 1, wherein the first rib material comprises chopped carbon fiber, carbon fiber powder, superconducting carbon black, graphite, silane coupling agent, titanate coupling agent, ethylene propylene diene monomer, polyethylene, and polypropylene.
3. The embedded self-sensing geogrid structure according to claim 2, wherein the chopped carbon fibers are filaments with a length of 1mm and a diameter of 7um, and the carbon fiber powder is a cuboid with a length of 30-50um and a diameter of 7 um.
4. The embedded self-sensing geogrid structure according to claim 1, wherein the wires in the plurality of rows of the second ribs are arranged at different heights, and the thermoplastic polymer strips are engraved with open grooves for arranging the wires.
5. The embedded self-sensing geogrid structure according to claim 1, wherein the latch material comprises carbon black, polyethylene, polypropylene, and ethylene propylene diene monomer.
6. The embedded self-sensing geogrid structure according to claim 1, wherein the mass fraction of each material in the first rib is as follows: 45-54% of polyethylene and 15-18% of polypropylene; 2-4% of chopped carbon fiber, 4-8% of carbon fiber powder and 4-6% of superconducting carbon black; 2-5% of graphite, 5-10% of silane coupling agent and 5-10% of titanate coupling agent; the ethylene propylene diene monomer is 6 to 12 percent.
7. The method of manufacturing a built-in self-sensing geogrid structure according to any of claims 1-6, comprising the steps of:
1) Preparing the first rib and the second rib respectively; 2) And splicing and connecting the first rib and the second rib.
8. The method of manufacturing according to claim 7, wherein the first rib is manufactured as follows:
1-1) taking chopped carbon fiber, carbon fiber powder, super-conductive carbon black and graphite as conductive fillers, uniformly mixing according to a set mass fraction, placing the mixture into mixed acid of concentrated sulfuric acid/concentrated nitric acid, adding industrial alcohol, and treating for a set time at a set temperature;
1-2) diluting the mixed solution obtained in the step 1) with clear water with a set volume, carrying out vacuum suction filtration with a microfiltration membrane, repeatedly diluting and carrying out suction filtration for many times until the filtrate becomes neutral, and drying at a set temperature for later use;
1-3) placing the conductive filler after acidification treatment, a silane coupling agent, a titanate coupling agent, ethylene propylene diene monomer rubber, polyethylene and polypropylene into a high-speed mixer for uniform mixing;
1-4) placing the uniform mixture into a double-screw extruder for extrusion granulation for a plurality of times;
1-5) putting the granules into an injection molding machine for melting, and injecting into conductive polymer strips with required sizes;
1-6) coating a layer of conductive silver adhesive at equal intervals according to the size of the required geogrid, and attaching a copper foil type conductive adhesive tape.
9. The method of manufacturing according to claim 7, wherein the second rib is manufactured by the following process:
2-1) carrying out melt blending injection molding on carbon black, polyethylene, polypropylene and ethylene propylene diene monomer according to a set mass fraction to obtain slices with required size;
2-2) positioning and marking a built-in wire path on the surface of the rack;
2-3) grooving the wire according to the marked wire path by using a grooving machine, wherein the groove depth is required to be 2-4 times of the diameter of the wire, and the groove depth is less than or equal to 1/3 of the thickness of the second rib;
2-4) firmly welding the lead and the copper circuit measuring point, embedding the lead and the copper circuit measuring point into the groove, and dripping glue for fixing;
2-5) filling and sealing the groove by using a thermoplastic machine, wherein the copper circuit measuring point is exposed;
2-6) uniformly coating conductive silver adhesive around the copper circuit measuring point, and timely pasting a copper foil type conductive adhesive tape.
10. The preparation method according to claim 7, wherein the specific steps of the step 2) are as follows:
3-1) adding carbon black, polyethylene, polypropylene and ethylene propylene diene monomer into a thermoplastic machine for melting for later use;
3-2) coating a layer of conductive silver glue on the first rib and the second rib, arranging conductive copper foils at the staggered position of the first rib and the second rib, splicing and aligning the conductive copper foils of the first rib and the second rib to communicate a circuit, and carrying out early consolidation treatment by using glue;
3-3) sealing and waterproofing the joint of the first rib and the second rib;
3-4) performing post-consolidation treatment on the joint of the first rib and the second rib by using a thermoplastic machine to form a thermoplastic lock catch, and completing the joint.
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| KR101244304B1 (en) * | 2011-10-20 | 2013-03-18 | 박현옥 | Detection system for the ground deformation |
| CN205115355U (en) * | 2015-11-20 | 2016-03-30 | 山东大学 | Sensing type geogrid structure |
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| US6079277A (en) * | 1997-12-12 | 2000-06-27 | The Research Foundation Of State University Of New York | Methods and sensors for detecting strain and stress |
| JP3418561B2 (en) * | 1997-12-26 | 2003-06-23 | 豊明 木村 | Conductive particle-polymer strain sensor |
| US8752438B2 (en) * | 2009-01-16 | 2014-06-17 | The Board Of Regents Of The University Of Oklahoma | Sensor-enabled geosynthetic material and method of making and using the same |
| CN206346085U (en) * | 2016-12-27 | 2017-07-21 | 山东路德新材料股份有限公司 | A kind of cross node GSZ |
| CN206346207U (en) * | 2016-12-29 | 2017-07-21 | 山东路德新材料股份有限公司 | A kind of antiskid steel moulds grid |
| CN206359973U (en) * | 2016-12-29 | 2017-07-28 | 山东路德新材料股份有限公司 | A kind of umbo point steel plastic geogrid with groove |
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| CN205115355U (en) * | 2015-11-20 | 2016-03-30 | 山东大学 | Sensing type geogrid structure |
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