CN111879823A - Polymer-based piezoelectric composite geotextile band for monitoring internal damage of geotechnical engineering and preparation method thereof - Google Patents

Abstract

The invention discloses a polymer-based piezoelectric composite geotechnical belt that can be used for internal damage monitoring of geotechnical engineering. It is composed of a mixture of electric ceramic particles and titanate coupling agent. The piezoelectric composite geotechnical belt is evenly distributed with a plurality of silver measuring sections, and the adjacent silver measuring sections are separated by 1CM. The upper and lower surfaces of the silver measuring sections are The silver electrode, the upper surface of the silver-measured segment is connected with a positive wire, and the lower surface of the silver-measured segment is connected with a negative wire. The piezoelectric composite geobelt has a wide range of applications, high self-sensing sensitivity and good linearity, and realizes distributed monitoring and early warning of internal damage in the whole life cycle of geotechnical engineering.

Description

A polymer-based piezoelectric composite geotechnical engineering for internal damage monitoring in geotechnical engineering Belt and method of making the same

technical field

The invention relates to a polymer-based piezoelectric composite geotechnical belt which can be used for internal damage monitoring of geotechnical engineering, and also relates to a preparation method of the polymer-based piezoelectric composite geotechnical belt which can be used for internal damage monitoring of geotechnical engineering.

Background technique

In recent years, with the large-scale construction of my country's transportation infrastructure, due to inadequate survey and design, imperfect construction, long-term natural disasters and other reasons, there have been collapsed retaining walls, tunnel collapses, subgrade damage, landslides, etc. in geotechnical engineering. Harm, causing heavy losses to people's lives and property. Pavement collapses due to subgrade damage, and train derailments caused by landslides occur frequently. Therefore, scholars at home and abroad have done a lot of research on geotechnical engineering monitoring and safety early warning.

In the current monitoring methods, the traditional discontinuous manual detection can only be detected after the surface of the inspected object is damaged, and the occurrence of major engineering casualties cannot be avoided in time. Therefore, it is of great significance to develop a distributed monitoring and early warning technology for internal damage in the whole life cycle of geotechnical engineering.

SUMMARY OF THE INVENTION

In view of the deficiencies of the background technology, the technical problem to be solved by the present invention is to provide a polymer-based piezoelectric composite geobelt that can be used for internal damage monitoring of geotechnical engineering. The piezoelectric composite geobelt has a wide range of applications, high self-sensing sensitivity and good linearity, and realizes distributed monitoring and early warning of internal damage in the entire life cycle of geotechnical engineering.

To this end, the present invention provides a polymer-based piezoelectric composite geobelt that can be used for internal damage monitoring in geotechnical engineering, including a piezoelectric composite geobelt body, and the piezoelectric composite geobelt body is composed of a polymer matrix, a conductive carbon Black, piezoelectric ceramic particles and titanate coupling agent are mixed. The piezoelectric composite geotextile is evenly distributed with a plurality of silver measuring sections, and the adjacent silver measuring sections are separated by 1CM. The upper surface of the silver measuring sections And the lower surface is covered with silver electrodes, the upper surface of the silver-measured section is connected with a positive wire, and the lower surface of the silver-measured section is connected with a negative wire.

The beneficial effects of the present invention,

(1) The piezoelectric composite geotextile belt can be applied to the internal damage monitoring of the roadbed, the internal damage monitoring of the slope, the internal damage monitoring of the retaining wall, the internal damage monitoring of the tunnel mountain, etc., and has a wide range of applications.

(2) The piezoelectric composite geotechnical belt can be buried separately, or attached to engineering structures such as steel bars and geogrids, which is convenient and quick to lay and will not damage the geotechnical engineering.

(3) When the internal damage occurs in the geotechnical engineering, the change of stress and strain causes the geotechnical belt to be stretched, bent, and the electric charge generated under the piezoelectric effect. The information of the electric charge can accurately determine the position and size of the deformation, and the self-perception sensitivity is high and the linearity is good.

(4) The polymer-based piezoelectric composite geobelt of the present invention solves the problems of traditional monitoring technology such as small range, short life, non-distributed monitoring and the like. The strain range can reach more than 10%, which realizes the distributed monitoring and early warning of internal damage in the whole life cycle of geotechnical engineering.

(5) The piezoelectric composite geobelt monitors the internal damage information, and transmits it wirelessly to the traffic control management center through the access device, reducing wiring and low maintenance costs.

Description of drawings

1 is a schematic diagram of a partial structure of a piezoelectric composite geobelt according to a first embodiment of the present invention;

Fig. 2 is a schematic diagram of the preparation process of a piezoelectric composite geobelt provided in Fig. 1;

Fig. 3 is the structural representation of the outer end face of a kind of piezoelectric composite geotextile provided by Fig. 1;

FIG. 4 is a schematic structural diagram of an outer end face of a piezoelectric composite geobelt according to the first embodiment of the present invention;

Fig. 5 is the structural representation inside the connector of a kind of piezoelectric composite geotextile provided by Fig. 4;

Fig. 6 is the structural representation of the connector section of a kind of piezoelectric composite geotextile provided by Fig. 5;

FIG. 7 is a schematic structural diagram at the connector A of a piezoelectric composite geotextile belt provided in FIG. 6;

FIG. 8 is a schematic structural diagram of the application of a piezoelectric composite geotextile belt in a roadbed provided by the present invention;

FIG. 9 is a schematic structural diagram of the application of a piezoelectric composite geotextile belt in a roadbed provided by the present invention.

Detailed ways

Referring to Figures 1, 2 and 3, a polymer-based piezoelectric composite geobelt that can be used for internal damage monitoring of geotechnical engineering in the present invention includes a piezoelectric composite geobelt body 1. The belt body 1 is composed of a polymer matrix, conductive carbon black, piezoelectric ceramic particles and a titanate coupling agent. The mass fraction of the polymer matrix is 50%-60%, and the mass fraction of the conductive carbon black is 5%- 15%, the mass fraction of the piezoelectric ceramic particles is 30-40%, and the mass fraction of the titanate coupling agent is 2%-5%. The polymer matrix is a high-density polyethylene matrix, and the piezoelectric ceramic particles are PZT-5 piezoelectric ceramic particles.

The piezoelectric composite geobelt body 1 is evenly distributed with a plurality of silver-measured sections 2, the silver-measured sections 2 are 10CM, and the adjacent silver-measured sections 2 are separated by 1CM. The lower surface is covered with silver electrodes, the upper surface of the silver-measured segment is connected with a positive wire 3, and the lower surface of the silver-measured segment is connected with a negative wire 4. The outer surface of the piezoelectric composite geobelt body 1 is encapsulated by PVC rubber material. At least one reinforcing rib 11 is provided on both lateral sides of the outer surface of the piezoelectric composite geobelt body 1 , the reinforcing rib 11 is in the shape of a triangular pyramid, and the piezoelectric composite geobelt is evenly distributed with anti-skid patterns 12 . When laying the geotechnical belt, the anti-skid pattern and reinforcing ribs increase the friction force with the geotechnical engineering, and it is not easy to cause sliding.

Referring to Fig. 2, a preparation method of a polymer-based piezoelectric composite geotextile that can be used for internal damage monitoring of geotechnical engineering, the steps are as follows,

(1) The polymer matrix, conductive carbon black and piezoelectric ceramic particles are finely ground and uniformly mixed by a planetary ball mill. The mass fraction of the polymer matrix is 50%-60%, and the polymer matrix is a high-density polyethylene matrix; the mass fraction of conductive carbon black is 5%-15%; the mass fraction of the piezoelectric ceramic particles is 30-40% %, the piezoelectric ceramic particles are PZT-5 piezoelectric ceramic particles.

(2) adding a titanate coupling agent to the mixture in step (1), and mixing uniformly, the mass fraction of the titanate coupling agent is 2%-5%.

(3) Feed the material through an automatic suction machine, and then melt and mix the mixture in step (2) through a twin-screw extruder. The twin-screw extruder fully melts the polymer matrix, conductive carbon black and piezoelectric ceramic particles. Stir and extrude to uniformly disperse the conductive carbon black and piezoelectric ceramic particles into the polymer.

(4) Next, through injection molding by an injection molding machine, the polymer-based piezoelectric composite geobelt after injection molding is cooled by blasting and water immersion, and then slowly removed under the traction of the traction device to make the piezoelectric composite geobelt with a thickness of 1.5mm, and cut according to the length and width of the actual project.

(5) A plurality of measuring sections are arranged on the piezoelectric composite geo belt 1, each measuring section has a length of 10CM, and the interval between adjacent measuring sections is 1CM. The upper and lower surfaces of the measuring sections are covered with silver electrodes, namely the measuring sections. For the silver-measured segment 2;

(6) The piezoelectric composite geotechnical belt is then subjected to a polarization process, wherein the polarization temperature is 80-100°C, the polarization voltage is 3kV/mm-6kV/mm, and the polarization time is 10min-30min. The upper surface of the silver-measured section is connected to the positive wire 3, and the lower surface of the silver-measured section is connected to the negative wire 4;

(7) Finally, use PVC rubber material to encapsulate the outer surface of the polymer-based piezoelectric composite geotextile.

1 , 2 , 4 , 5 , 6 and 7 , a piezoelectric composite geobelt according to the second embodiment of the present invention, the two sides of the outer surface of the piezoelectric composite geobelt body 1 are longitudinally A plurality of longitudinal grooves 13 are evenly distributed. The inner wall of the longitudinal groove 13 on the outer surface of the piezoelectric composite geo belt body is a smooth surface, and the other parts outside the inner wall of the longitudinal groove 13 of the piezoelectric composite geo belt are evenly distributed with anti-skid patterns 12 . The piezoelectric composite geobelt body is connected with a connector 14. When the piezoelectric composite geobelt is laid, when the end of the geobelt needs to be connected to the next geobelt, the connector 14 is used to connect two adjacent sections of the geobelt, which is extremely convenient to use. .

The connecting head 14 includes a casing 15 and a connecting cover 16 , the lower end of the casing 15 has an opening, one end of the connecting cover 16 is hinged on one side of the opening of the casing, and the other end of the connecting cover 16 is fastened to the casing 15 . The outer end face on the other side of the opening. The outer end surface of the other side of the opening of the casing 15 is provided with a fastener 17 , the inward side of the fastener 17 has a slot 18 , and a hook 19 is arranged in the slot 18 . The connection cover 16 has a clip 20 adapted to the fastener 17 , and the clip 20 has a clip slot 21 at the bottom. The inner cavity of the housing 15 has four strip-shaped projections 22, and the strip-shaped projections 22 are arranged opposite to each other, that is, two pairs of strip-shaped projections 22 are arranged in the inner cavity of the housing 15, and the strip-shaped projections 22 and the pressure The longitudinal grooves 13 on the outer surface of the electric composite geobelt body are adapted to fit. When connecting adjacent geotechnical belts, the geotechnical belt is inserted into the opening of the casing 15 , and the strip-shaped protrusions 22 are inserted into the longitudinal grooves 13 . The two pairs of strip-shaped projections 22 in the casing are respectively inserted into the longitudinal grooves 13 at the ends of the adjacent two geotechnical belts, and each pair of strip-shaped projections are respectively inserted into the clamping grooves on both sides of the geotechnical belt. When the connection cover 16 is in a snap-fit state, the hook member 19 is snapped into the snap-fit slot 21 .

Referring to FIG. 8 , the first embodiment of a polymer-based piezoelectric composite geo belt that can be used for internal damage monitoring of geotechnical engineering in the present invention is applied to a roadbed application method. First of all, the polymer-based piezoelectric composite geotextile is intended to be buried in the roadbed 5, or attached to the geogrid of the reinforced soil, which is convenient and quick to lay and will not damage the geotechnical engineering. Then, connect the positive wire 3 and the negative wire 4 on the silver-measured section 2 to the accessor 6 on the side of the roadbed, and the accessor includes a signal processing system and a wireless signal transmission system.

When the slip surface occurs, the change of stress and strain causes the piezoelectric composite geobelt body 1 located in the center of and near the slip surface to be stretched, bent, and the like. The piezoelectric composite geobelt body 1 undergoes different degrees of strain according to the different stresses received. The strained geotextile belt located in the center of the slip surface 8 has a large strain, and the strained geotechnical belt located near the slip surface 8 has a large strain. The strained part of the polymer-based piezoelectric composite geotechnical belt 1 generates charges due to the piezoelectric effect, and the information is transmitted to the access device 6 through the positive wire 3 and the negative wire 4. After being processed by the signal processing system, the wireless signal transmission system The location and magnitude of the charge are communicated to the traffic control management center. The position and size of the deformation can be accurately judged by monitoring the size and position of the electric charge generated by the piezoelectric effect of the polymer-based piezoelectric composite geotechnical belt 1, with high self-sensing sensitivity and good linearity.

Using the pull-sensing effect of the polymer-based piezoelectric composite geotextile, according to the transmission information of the positive wire 3 and the negative wire 4, the magnitude of the impedance change with the strain is measured, the change of the impedance reconfirms the deformation information, and the degree of internal damage and deformation is determined according to the change of the impedance. . Then the deformation information is transmitted to the traffic control and management center through the wireless signal transmission system of the access device, and the staff processes the information in time to avoid major engineering casualties such as roadbed damage and road collapse.

Referring to Figure 9, a second embodiment of a polymer-based piezoelectric composite geotextile that can be used for internal damage monitoring of geotechnical engineering in the present invention is applied to the application method of the slope along the railway:

A polymer-based piezoelectric composite geobelt body 1 is arranged on each hillside of the continuous hillside where the train 7 passes. The piezoelectric composite geotechnical belt 1 can be embedded separately or attached to engineering structures such as steel bars and geogrids. When a landslide occurs, the landslide surface 9 strains or even breaks the polymer-based piezoelectric composite geotextile belt 1 . The size and position of the electric charges generated by the piezoelectric effect are used, and the tensile force of the polymer-based piezoelectric composite geotechnical belt 1 is used. Sensitive effect, monitoring electrical impedance deformation. According to the generated charge information and the tested piezoelectric impedance information, the wireless signal transmission system is transmitted to the traffic information management center through the access device 6 . The traffic information management center confirms the landslide through the satellite monitoring station 10, and transmits the landslide information to the train. The train braked in time to avoid major engineering casualties such as train derailment.

The piezoelectric composite geobelt body 1 can also be applied to other geotechnical engineering, and the piezoelectric composite geobelt body can be monitored, internal damage monitoring of slopes, internal damage monitoring of retaining walls, internal damage monitoring of tunnel mountains, and the like.

The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims (10)

1. A polymer-based piezoelectric composite geotechnical belt for monitoring internal damage of geotechnical engineering is characterized in that: the piezoelectric composite geotextile band comprises a piezoelectric composite geotextile band body, wherein the piezoelectric composite geotextile band body is formed by mixing a polymer matrix, conductive carbon black, piezoelectric ceramic particles and a titanate coupling agent, a plurality of sections to be measured by silver are uniformly distributed on the piezoelectric composite geotextile band, the upper surface and the lower surface of the section to be measured by silver electrodes are connected with an anode lead by the upper surface of the section to be measured by silver, and the lower surface of the section to be measured by silver is connected with a cathode lead.

2. The polymer-based piezoelectric composite geotechnical belt for monitoring internal damage of geotechnical engineering according to claim 1, wherein: the mass fraction of the polymer matrix is 50-60%, the mass fraction of the conductive carbon black is 5-15%, and the mass fraction of the piezoelectric ceramic particles is 30-40%.

3. The polymer-based piezoelectric composite geotechnical belt for monitoring internal damage of geotechnical engineering according to claim 2, wherein: the mass fraction of the titanate coupling agent is 2-5%.

4. The polymer-based piezoelectric composite geotechnical band for internal damage monitoring in geotechnical engineering according to claim 1, 2 or 3, wherein: the polymer matrix is a high-density polyethylene matrix, and the piezoelectric ceramic particles are PZT-5 piezoelectric ceramic particles.

5. The polymer-based piezoelectric composite geotechnical belt for monitoring internal damage of geotechnical engineering according to claim 4, wherein: the section to be tested silver is 10CM, and the interval between adjacent sections to be tested silver is 1 CM.

6. The polymer-based piezoelectric composite geotechnical band for internal damage monitoring in geotechnical engineering according to claim 1, 2, 3 or 5, wherein: the outer surface of the piezoelectric composite geotechnical belt body is packaged by PVC rubber materials.

7. The polymer-based piezoelectric composite geotechnical belt for monitoring internal damage of geotechnical engineering according to claim 6, wherein: the horizontal both sides of piezoelectricity composite geotechnique's area body surface have an at least strengthening rib, piezoelectricity composite geotechnique's area equipartition has anti-skidding decorative pattern.

8. The polymer-based piezoelectric composite geotechnical belt for monitoring internal damage of geotechnical engineering according to claim 6, wherein: the horizontal both sides of piezoelectricity composite geotechnique's area body surface have an at least strengthening rib, the vertical evenly distributed a plurality of vertical grooves in piezoelectricity composite geotechnique's area body surface both sides, the vertical inslot wall in piezoelectricity composite geotechnique's area body surface is the smooth surface, other part equipartitions outside the vertical inslot wall in piezoelectricity composite geotechnique's area have anti-skidding decorative pattern.

9. The polymer-based piezoelectric composite geotechnical belt for monitoring internal damage of geotechnical engineering according to claim 8, wherein: the connector is connected to the piezoelectric composite geotechnical belt body and comprises a shell and a connecting cover, an opening is formed in the lower end of the shell, one end of the connecting cover is hinged to one side of the opening of the shell, and the other end of the connecting cover is buckled on the outer end face of the other side of the opening of the shell.

10. A method for preparing the polymer-based piezoelectric composite geotextile band for monitoring geotechnical engineering internal damage according to claim 1, wherein the method comprises the following steps: the steps are as follows,

(1) finely grinding and uniformly mixing the polymer matrix, the conductive carbon black and the piezoelectric ceramic particles by a planetary ball mill;

(2) adding a titanate coupling agent into the mixture obtained in the step (1), and uniformly mixing;

(3) melting and mixing the mixture obtained in the step (2) by a double-screw extruder, fully melting the polymer matrix, the conductive carbon black and the piezoelectric ceramic particles by the double-screw extruder, and uniformly dispersing the conductive carbon black and the piezoelectric ceramic particles into the polymer by stirring and extruding;

(4) then, injection molding is carried out through an injection molding machine, blowing and water immersion cooling are carried out, then the piezoelectric composite geotextile strip is slowly moved out under the traction of a traction device, the thickness of the manufactured piezoelectric composite geotextile strip body is 1.5mm, and cutting is carried out according to the length and the width of the actual engineering;

(5) arranging a plurality of measuring sections on the piezoelectric composite geotechnical belt, wherein the length of each measuring section is 10CM, the interval between every two adjacent measuring sections is 1CM, the upper surface and the lower surface of each measuring section are both coated with silver electrodes, and each measuring section is a silver-coated measuring section;

(6) carrying out polarization process treatment on the piezoelectric composite geotextile band, wherein the upper surface of the section to be silver-measured is connected with a positive lead, and the lower surface of the section to be silver-measured is connected with a negative lead;

(7) and finally, packaging the outer surface of the polymer-based piezoelectric composite earthwork belt by adopting a PVC rubber material.

Images