JP2002221457A - Method and device for measuring axial force of anchor material which uses optical fiber sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow easy installation and application to an anchor device from outside an object structure body, regardless of existing one or new one, by eliminating a fear of damaging an optical fiber at installing the anchor when an optical fiber sensor is used for measuring an axial force of an anchor material. SOLUTION: On the side opposed to a structure body 1 of a bearing material 4 pressurized to the structure body 1 by an anchor material 3, a tension material 8 is provided which, connected to the anchor material, is so supported as to receive a tension equal to or proportional to the one acting on the anchor material and cause a strain according to a value of the tension. A strain sensor 10a of an optical fiber is fitted to the tension material, and the signal of a strain acquired from the sensor which receives a strain equivalent to that of the tension material is analyzed to detect an axial force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an anchor material (an curtain rod) fixed to a structure, and presses a bearing material disposed on the surface of the structure against the surface of the structure by the tension of the anchor material. The present invention relates to an anchor material axial force measuring method and device for monitoring and measuring the tension applied to an anchor material in an anchor device for protecting a structure.

The above-mentioned structures are ground, ground, concrete structures and the like, and the above-mentioned bearing members are pressure receiving plates, retaining walls, tunnel structures, bridge pier foundations, concrete foundations of steel towers and the like in slope stabilization works. is there. The anchor material may be, for example, one or a plurality of PC steel strands, a bundle of PC steel strands, a wire, a metal rod (steel rod), a composite material (for example, a non-metal material such as an FRP material or carbon fiber), or the like. It is composed of

[0003]

2. Description of the Related Art Generally, an anchor material is inserted into an anchor hole formed in a target structure such as a ground, a ground, a concrete structure, or the like, and an end in an insertion direction is fixed to the target structure by cement milk or the like, and the opposite side is inserted. The end of the anchor material is led out of the anchor hole and is connected to the supporting member.

[0004] The connection between the bearing material and the anchor material is generally
The end of the anchor material is led out to the opposite side to the target structure through the through-hole provided in the supporting material and the anchor plate superimposed on the bearing material, and the end of the led anchor material is fixed to the male screw member of the anchor head. This is performed by placing a female screw member screwed into a male screw member on an anchor plate. Therefore, by turning the female screw member and tightening in the direction of the anchor plate, the anchor plate and the bearing member are pressed toward the target structure, and a tension or an axial force is applied to the anchor member according to the degree of the tightening. Hang on.

[0005] Conventionally, when a new anchor is installed in order to monitor and measure the axial force applied to the anchor material, a load cell is bitten (pinched) between the anchor plate and the female screw member. There has been proposed an apparatus that detects a change in tension of an anchor member from an electric change caused by a distortion of a load cell.

However, since the load cell deteriorates with time due to corrosion or the like, accurate measurement values cannot be obtained gradually for a long use of several decades or more, which is the service life of the anchor. There are drawbacks.
In addition, since the electric system is used, it is susceptible to lightning and electromagnetic waves, and has a disadvantage that it malfunctions or does not function. Replacing the installed load cell is difficult in terms of cost, labor and time.

[0007] In addition to the load cell as described above, an optical fiber sensor is attached to an anchor material before the anchor is inserted into an anchor hole, and information from the optical fiber sensor is installed after the anchor is installed. A method has also been proposed in which the anchor material is received on the ground through the ground and the axial force of the anchor material is known based on the information.

Although this method is extremely effective in that accurate and quick measurement can be performed, when the anchor material is inserted and fixed in the anchor hole, the optical fiber attached to the anchor material is not damaged or broken. There is still room for improvement in that protective devices and careful attention are required.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention uses an optical fiber sensor capable of providing accurate measurement values over a long period of time, eliminates the fear of damage to the optical fiber at the time of anchor installation, and reduces the possibility of existing or new installation. It is an object of the present invention to provide a method and an apparatus for measuring an axial force of an anchor material which can be easily installed and applied to an anchor device outside the structure (for example, on the ground) regardless of the structure.

[0010]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 of the present invention has an anchor material fixed in a structure, and is disposed on the surface of the structure. In a method of measuring an axial force of an anchor material in an anchor device for protecting a structure by pressing a bearing material against a surface of a structure by a tension applied to the anchor material, the anchor material is connected to the anchor material on a side opposite to the structure. Then, a tension member which receives a tension equal to or proportional to the tension applied to the anchor material and is supported so as to generate a strain according to the value of the tension is provided, and an optical fiber strain sensor is attached to the tension member. And a strain signal corresponding to the strain of the strain sensor is sent to the measuring instrument via the optical fiber.

The above-mentioned tensile material may be, for example, one or a plurality of PC steel stranded wires, PC steel stranded bundles, wires, metal rods (steel rods), composite materials (for example, non-metallic materials such as FRP materials, carbon fibers, etc.) Materials) and the like.

An optical fiber strain sensor (so-called FBG)
The sensor is a known one, and for example, a part of an optical fiber is converted into a fiber grating (Fiber Bragg).
gGrating) processing.

According to the first aspect of the present invention, the FBG sensor can be attached after the anchor material is fixed.
It is not necessary to consider and take measures to avoid damage to the G sensor and the optical fiber connected to it when anchoring the anchor material. After installing the FBG sensor, accurate and quick measurement of the axial force of the anchor material over the service life of the anchor The present invention can be easily applied to an existing anchor as well as a new anchor.

According to a second aspect of the present invention, the end of the tension member is fixed to a main anchor head mounted on an anchor plate spaced apart from the bearing member on the side opposite to the structure. And

According to the second aspect of the invention, it is possible to easily apply the same axial force to the tensile member as that of the anchor member.

According to a third aspect of the present invention, there is provided a cylindrical spacer between the supporting member and the main anchor plate, which keeps a space therebetween and surrounds the tension member. And

According to the third aspect of the present invention, the anchor plate can be securely held to the supporting member, and the tension member disposed therein and the strain sensor fixed to the tension member are provided. Can be protected.

The invention according to claim 4 is characterized in that the tension member is formed by an extension of the anchor member.

According to the fourth aspect of the present invention, it is possible to easily form the tensile member.

According to a fifth aspect of the present invention, the head-side end portion of the anchor member is formed on the supporting plate on the supporting member.
In a case where the tension member is fixed to the anchor head, an end portion of the tension member on the anchor material side is fixed to a coupling block which is separated from and opposed to the second anchor head, and the coupling block and the second anchor head are fixed to each other. It is characterized by being interconnected.

According to the fifth aspect of the present invention, since the second anchor head corresponds to the anchor head of the existing anchor device, the method of the present invention can be easily applied to the existing anchor device. .

According to a sixth aspect of the present invention, there is provided an anchor member fixed in the structure, and the supporting member disposed on the surface of the structure is pressed against the surface of the structure by the tension applied to the anchor member. An anchor member axial force measuring device in an anchor device for protecting a structure by means of a main anchor head disposed above and spaced apart from a bearing member, and a tension member having one end fixed to the main anchor head. A coupling device for coupling the tension member to the anchor member, an optical fiber having a strain sensor fixed to the tension member so as to receive the same strain as the tension member, and an optical fiber coupled to the optical fiber and connected to the optical fiber. And a measuring device for measuring an axial force applied to the tensile member from a strain signal sent through the measuring device.

The tensile member may be, for example, one or a plurality of PC steel strands, a bundle of PC steel strands, a wire, a metal rod (steel rod), or a composite material (for example, a non-metallic material such as FRP material or carbon fiber). Etc.

According to the sixth aspect of the present invention, the present invention can be easily applied not only to a newly installed anchor device but also to an existing anchor device, and it is possible to accurately and reliably measure the axial force of an anchor material. it can.

According to a seventh aspect of the present invention, there is provided the above-mentioned coupling device, wherein the coupling block is fixedly attached to the anchor member side end of the tension member, and both the coupling block and the second anchor head are screw-coupled. And a possible coupler. The invention described in claim 8 is:
The coupling device has a coupling block fixedly attached to the anchor material side end of the tension member, and a coupler that can be screw-coupled to both the coupling block and the anchor material head. And

According to the seventh and eighth aspects of the present invention, the coupling between the tension member and the anchor member is achieved only by screwing the coupler to the tension member and the second anchor head or the screw provided on the anchor member head. Is easily achieved. In the case of the anchor device having the second anchor head, regardless of the new or existing anchor device, the second anchor device is used for retraction of the anchor material.
Since it is common to provide a screw for engaging the traction device on the anchor head or the head of the anchor material, it is effective to use this screw for coupling with the coupler.

According to a ninth aspect of the present invention, between the second anchor head and the anchor plate carrying the main anchor head, a tubular spacer for maintaining a space between the two anchors surrounds the tension member. The spacer is filled with an anticorrosion material.

According to the ninth aspect, the tensile member is protected from losing its function due to corrosion.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, taking an example in which the present invention is applied to slope stabilization.

FIG. 1 is a schematic longitudinal sectional view of an anchor device 2 fixed to a ground 1 as a structure.
3 is an anchor material, 4 is a bearing material (for example, a concrete or steel pressure receiving plate, a concrete frame, a concrete block) arranged on the surface of the ground 1, 5 is a main anchor plate, and 6 is connected to the anchor material 3. The main anchor head 7 holding the end of the tension member 8 is a cylindrical support spacer inserted between the supporting member 4 and the main anchor plate 5. The main anchor head 6 has a function of adjusting the axial force of the anchor member 3 via the tension member 8, and the supporting member 4
The adjusted axial force applied through the main anchor plate 5 and the supporting spacer 7 is pressed against the slope or the slope 1a of the ground 1 to stabilize the slope and prevent slipping or collapse.

FIGS. 2 to 6 show examples of the embodiment for measuring the axial force of the anchor member 3. The anchor plate 5, the main anchor head 6, the spacer 7, and the supporting plate 9 are provided in each embodiment. It is a common member.

In the embodiment shown in FIG. 2, the anchor member 3 is formed by one steel rod or one strand of PC steel, and the tensile member 8 penetrates the bearing member 4 and the bearing plate 9. It is configured as an extension of the anchor material 3 which extends. In this embodiment, the end of the tension member 8 is formed as a threaded rod 8a, and the main anchor head 6 is connected to the threaded rod 8a.
Is formed as a nut that is screwed into the nut. Therefore, the axial force of the anchor member 3 can be adjusted by turning the nut 6 in a state where it is installed as illustrated.

The tensile material 8 has an FBG of the optical fiber 10
The sensor 10a is fixed, and the fixing is performed in such a manner that the FBG sensor receives the same distortion as the distortion generated in the tensile member 8 when the tension fluctuation occurs or the distortion is proportional to the distortion. An example of a specific fixing method will be described later with reference to FIGS.

The optical fiber 10 is led out of the supporting spacer 7 and connected to the junction box 11 as shown in FIG. This relay box is connected to an optical switch 12, a measuring instrument 13, and a control personal computer 14 as shown in the figure.

The axial force of the anchor member 3 is confirmed as follows. That is, the change in the strain caused by the change in the axial force of the anchor member 3 also appears in the tension member 8 and the FBG sensor 10a also deforms accordingly, so that the optical signal indicating the degree of the distortion is transmitted from the optical fiber 10 to the junction box 11, The current axial force of the anchor member 3 is confirmed by bringing it to the measuring device 13 via the optical switch 12 and calculating the measured value by the computer 14.

In the case of the embodiment shown in FIG. 3, the anchor member 3 is composed of three steel rods or three strands of PC steel, and the tension member 8 is constituted by an extension of the three anchor members. The FBG sensor 10a is fixed to the tension member 8. Although the figure shows a case in which the FBG sensor 10a is fixed to two steel rods or stranded wires in the tensile member 8, it may be fixed to one or all of them. F
The strain measurement of the BG sensor 10a and the calculation of the axial force from the measured value are performed in the same manner as described with reference to FIG.

In the embodiment shown in FIG. 3, the main anchor head 6 for holding the end of the tension member 8 is configured as follows. That is, the main anchor head 6 has an inner male screw block fixedly holding the end of the tension member 8,
And an outer female screw block screwed into the male screw block. Therefore, in the illustrated installation state,
By turning the female screw block with respect to the male screw block and tightening it in the direction of the bearing member 4 or turning it in the opposite direction to loosen it, the anchor material 3 is passed through the main anchor plate 5 and the supporting spacer 7. 2, the supporting member 4 is pressed against the slope 1 or the slope 1a of the ground 1 by the adjusted axial force as in the case of FIG. Prevent collapse. In addition, also in the embodiment of FIG. 2, the anchor head 6 may be configured similarly to the case of FIG.

In another embodiment shown in FIG. 4, the anchor member 3 and the tension member 8 consist of one steel rod or one strand of PC steel. The anchor member 3 has a male screw portion at an upper end thereof, and the male screw portion is screwed into a female screw formed on the second anchor head 16 mounted on the supporting plate 9 so as to engage with the second anchor head 16. And protrudes upward from the second anchor head.

The anchor member 3 and the tension member 8 are the coupler 1
The coupling between the coupler 15 and the head of the anchor member 3 is performed by screwing a female screw provided at one end of the coupler with a male screw portion of the anchor member head. The coupling with the coupler 15 is performed by screwing a male screw portion provided at the end of the tension member 8 with a female screw provided at the other end of the coupler 15. The connection between the upper end of the tension member and the anchor head 6 is the same as in the case of FIG.

The second anchor head 16 normally bears the axial force of the anchor member 3 and exerts the axial force of the anchor member 3 on the bearing member 4 via the bearing plate 9. Therefore, in order to measure the axial force of the anchor member 3, the main anchor head 6 is operated to pull the tension member 8, the second anchor head 16 is detached from the bearing plate 9, and the second anchor head is not operated. Therefore, after the axial force of the anchor member 3 is applied directly to the tension member 8, the degree of distortion of the FBG sensor 13a is measured.

The embodiment shown in FIG.
Tensile material 8 consists of one steel rod or one PC steel strand, and consists of one steel rod or three PC steel strands. The head of the anchor material 3 is held by a second anchor head 16 having a configuration similar to that of the main anchor head 6 shown in FIG. 3, and the second anchor head 16 is, as in the case of FIG. 3, and exerts the axial force of the anchor member 3 on the support member 4 via the support plate 9.

The tension member 8 is held at one end by the main anchor head 6 on the anchor plate 5 as in the case of FIG. In order to connect the other end of the tension member 8 to the anchor member 3, as in FIG. 4, a coupler 15 is provided, which is screwed on the one hand to a second anchor head 16 and on the other hand to the tension member 8 Is screwed. The second anchor head 16 includes an inner male screw block fixedly holding an end of the anchor material 3 as described with reference to the main anchor head 6 of FIG.
And an outer female screw block screwed into the male screw block. This male screw block can be used for screw connection with the coupler 15. That is, a female screw is formed at one end of the coupler to be screwed with the male screw of this block. At the other end of the coupler, a female screw portion to be screwed with a male screw portion provided below the tension member 8 is formed.

An FBG sensor 10a is fixed to the tension member 8, and the optical fiber 10 provided with the FBG sensor is connected to a junction box 11 shown in FIG.

In the embodiment shown in FIG. 5, as in the case of FIG. 4, in order to measure the axial force of the anchor member 3, the main anchor head 6 is operated to pull the tension member 8, and the second anchor After the head 16 is disengaged from the bearing plate 9 so that the second anchor head does not work, so that the axial force of the anchor member 3 is directly applied to the tension member 8, the FB
The degree of distortion of the G sensor 10a is measured.

The embodiment shown in FIG. 5 has a plurality (three in the figure).
Since the tension member 8 is composed of one wire or bar, the axial force applied to each wire or bar of the anchor 3 is not uniform. However, the tensile member 8 is advantageous in that the axial force of the entire anchor member is concentrated.

In the embodiment shown in FIG. 6, the anchor member 3 is composed of three steel rods or three PC steel strands, and the tension member 8 is also composed of three steel rods or three PC steel strands. Consists of The head of the anchor member 3 is the same as that of FIG.
It is held by an anchor head 16. The upper end of the tension member 8 is held by the main anchor head 6 similar to that described with reference to FIG. The connection between the tension member 8 and the anchor member 3 is performed by a coupling device formed of a coupling block 17 coupled to a lower portion of the tension member 8, a coupler 15, and a second anchor head 16.

The screw connection between the second anchor head 16 and the coupler 15 is performed in the same manner as in the embodiment of FIG. The coupling between the coupling block 17 and the coupler 15 is performed by screwing a male screw provided on the outer periphery of the coupling block 17 and a female screw provided on the coupler 15.

The attachment of the FBG sensor 10a to the tension member 8 may be performed on two of the three steel rods or strands as shown in the figure, or only one, or three.
It may be performed for the whole book.

In this embodiment, as in the case of FIGS. 4 and 5, to measure the axial force of the anchor member 3, the main anchor head 6 is operated to pull the tension member 8, and the second anchor The head 16 is disengaged from the bearing plate 9 so that the second anchor head does not work, so that the axial force of the anchor member 3 is directly applied to the tension member 8, and then F
The degree of distortion of the BG sensor 10a is measured.

In each of the above embodiments, the cylindrical support spacer 7 is provided with a door 7a for maintenance, and the inside of the spacer 7 is filled with an anticorrosive material, for example, grease. In each figure, reference numeral 18 denotes a cap for protecting the main anchor head 6.

As described above, the FBG sensor 10 a of the optical fiber 10 is fixed to the tensile member 8,
The strain is performed in such a manner that the FBG sensor receives a strain equal to or proportional to the strain generated when the tensile member 8 receives the tension.

FIGS. 7 to 9 are partial views showing some examples of a method of fixing the FBG sensor 10a to the tension member 8, and FIGS. 7A and 7B show a case where PC steel is used as the tension member. The case where the FBG sensor 10a is fixed to the wire 8 with the adhesive 20 is shown. In the case of (A), the extending direction of the sensor is made parallel to the axis of the PC steel strand, and (B)
In the case of, the sensor extends along one strand forming a stranded wire. FIG. 7C shows the stranded wire 8 and the sensor 1
The mutual situation between Oa and the adhesive 20 is shown in the central longitudinal section of the stranded line. In the figure, 21 is the sensor 10
This is a covering sheet affixed over the sensor in order to protect a from the surrounding anticorrosive grease.

FIG. 8 shows a sensor 1 attached to a steel rod 8 as a tensile member.
FIG. 8 (A) shows a state where the sticking portion is viewed from the front, and FIG. 8 (B) shows a state where it is viewed from the side. The sensor 10a is protected by the covering sheet 21.

FIG. 9 shows a case in which the FBG sensor is fixed to the steel rod 8 by using a fixture 22 instead of attaching the sensor, and the optical fiber between the fixtures is The steel bar is tensioned with a certain tension so that the strain generated in the steel bar is transmitted to the sensor 10a.

[0055]

According to the present invention, it is possible to easily provide an anchor material axial force measuring means in an anchor device irrespective of whether it is new or existing, and to accurately measure the axial force over the entire service life of the anchor material. In addition, since the members involved in the measurement including the sensor are arranged outside the target structure to be protected, maintenance and inspection are easy.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for measuring an axial force of an anchor member according to the present invention and an apparatus for implementing the method.

FIG. 2 is a central longitudinal sectional view showing a main part of an embodiment of an anchor material axial force measuring device according to the present invention.

FIG. 3 is a central longitudinal sectional view showing a main part of another embodiment of the anchor material axial force measuring device according to the present invention.

FIG. 4 is a central longitudinal sectional view showing a main part of still another embodiment of the anchor member axial force measuring device according to the present invention.

FIG. 5 is a central vertical sectional view showing a main part of still another embodiment of the anchor member axial force measuring device according to the present invention.

FIG. 6 is a central vertical sectional view showing a main part of still another embodiment of the anchor member axial force measuring device according to the present invention.

FIGS. 7A and 7B are views showing a state of fixing an optical fiber sensor to a stranded wire as a tension member, wherein FIGS. 7A and 7B are diagrams showing a state where the fixing portion is viewed from the front, and FIG. It is a longitudinal cross-sectional view.

FIGS. 8A and 8B are views showing a mode of fixing the optical fiber sensor to a steel rod as a tensile member, where FIG. 8A is a view of a state where the fixing portion is viewed from the front, and FIG. 8C is a side view of FIG. is there.

FIG. 9 is a diagram showing another mode of fixing the optical fiber sensor to the steel rod.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ground 1a ... Slope 2 ... Anchor device 3 ... Anchor material 4 ... Bearing material 5 ... Anchor plate 6 ... Main anchor head 7 ... Spacer 8. ··· Tensioning material 9 ··· Support plate 10 ··· Optical fiber 10a ··· Optical sensor 11 ··················································・ Coupler 16 ・ ・ ・ Second anchor head 17 ・ ・ ・ Connecting block 18 ・ ・ ・ Cap 20 ・ ・ ・ Adhesive 21 ・ ・ ・ Coating sheet

Continued on the front page (72) Inventor Yuzo Ooka 1-2-14, Mitsudai, Hachioji-shi, Tokyo (72) Inventor Hiroshi Nakai 1-483-1-901, Mitsuhashi, Omiya-shi, Saitama (72) Inventor Yasuo Maeda Kanagawa 1-222-10-404, Kosugaya, Sakae-ku, Yokohama-shi (72) Inventor: Hara Zhang 7-21-20-602 Naka-Kasai, Edogawa-ku, Tokyo F-term (reference) 2D041 GA01 GB01 GC12 GC14 GD02 2E164 AA02 AA31 DA22 2F051 AA06 AB03

Claims (9)

[Claims] An anchor material is fixed in a structure, and a supporting member disposed on the surface of the structure is pressed against the surface of the structure by a tension applied to the anchor material to protect the structure. In the method of measuring the axial force of the anchor material in the anchor device, on the side opposite to the supporting material, connected to the anchor material, receives a tension equal to or proportional to the tension applied to the anchor material, and according to the value of the tension. A tensile member supported to generate strain is provided, and an optical fiber strain sensor is fixed to the tensile member so as to receive the same strain as the tensile member, and a strain signal corresponding to the strain of the strain sensor is transmitted through the optical fiber. A method for measuring the axial force of an anchor material, which is sent to a measuring instrument. 2. The method according to claim 1, wherein the end of the tension member is fixed to a main anchor head mounted on an anchor plate spaced away from the bearing member on the side opposite to the structure. The method for measuring the axial force of the anchor material described in the above. 3. Between the bearing member and the main anchor plate,
The method according to claim 1, further comprising providing a cylindrical spacer that holds a space between the two and surrounds the tension member. 4. The method for measuring an axial force of an anchor material according to claim 1, wherein the tension member is formed by an extension of the anchor material. 5. When the head-side end of the anchor member is fixed to a second anchor head on a bearing plate placed on the bearing member, the anchor member-side end of the tensile member is fixed to the anchor member. The second anchor head is fixed to a connecting block which is separated from and opposed to the second anchor head, and the connecting block and the second
Characterized by interconnecting the anchor head and
The method for measuring an axial force of an anchor material according to claim 1. 6. An anchor material anchored in the structure,
In the anchor material axial force measuring device in the anchor device for protecting the structure by pressing the bearing material arranged on the surface of the structure against the surface of the structure by the tension given to the anchor material, A main anchor head spaced apart above the main anchor head, a tension member having one end fixed to the main anchor head, a connecting device for connecting the tension member to the anchor material, and a tension member equivalent to the above tension member. An optical fiber having a strain sensor fixed so as to receive the strain, and a measuring device coupled to the optical fiber and measuring an axial force applied to the tensile member from a strain signal sent from the strain sensor via the optical fiber, An anchor material axial force measuring device, comprising: 7. The coupling device according to claim 1, further comprising: a coupling block fixedly attached to the anchor material-side end of the tension member; and a coupler that can be screw-coupled to both the coupling block and the second anchor head. Characterized by the fact that
The anchor material axial force measuring device according to claim 6. 8. The coupling device according to claim 1, further comprising: a coupling block fixedly attached to the anchor material side end of the tension member; and a coupler capable of being screw-coupled to both the coupling block and the anchor material head. The anchor member axial force measuring device according to claim 6, wherein the anchor member axial force measuring device is used. 9. A tubular spacer surrounding the tension member is provided between the second anchor head and the anchor plate carrying the main anchor head to maintain a space therebetween. The device according to any one of claims 6 to 8, wherein the spacer is filled with an anticorrosion material.