Intra-sheath observation method using an endoscope

Abstract

To provide an intra-sheath observation method using an endoscope that is convenient to use and can prevent the endoscope from being damaged when a grout filling state in a sheath of a PC structure is observed using the endoscope.SOLUTION: An intra-sheath observation method using an endoscope observes a grout filling state in a sheath 2 of a PC structure 1 using an endoscope (video scope unit 7). A protection tube 5 for protecting a cable (insertion unit 75) of the endoscope (video scope unit 7) into which a spiral metal wire (spiral steel wire 51) that is a spring material is inserted into a resin tube 50 is inserted into the sheath 2 and a grout filling state in the sheath 2 is observed using the endoscope (video scope unit 7).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for observing inside a sheath using an endoscope, and more particularly to a method for observing inside a sheath using an endoscope (fiberscope or videoscope) that can prevent damage to the endoscope by inserting an endoscope protection tube beforehand onto the outside of the endoscope when observing the grout filling status inside the sheath of a PC structure using the endoscope. [Background technology]

[0002] In post-tensioned PC structures, PC steel members are inserted into a sheath placed inside the concrete structure. After the specified concrete strength is reached, tension (prestress) is applied to the PC steel members, and grout is filled into the sheath to prevent rust.

[0003] However, in recent years, corrosion of the PC steel members due to insufficient grout filling inside the sheath has become a problem, and various methods for observing inside the sheath have been proposed to check whether there are any areas inside the sheath that are not filled with grout.

[0004] For example, Patent Document 1 discloses a method of checking the filling of grout material, in which an inspection hole 3a is formed in a sheath 3, an exploration path 5 is formed adjacent to the inspection hole 3a and communicating with one of the surfaces of a prestressed concrete member 1, and the prestressed concrete member 1 is manufactured in a state in which the inside of the sheath 3 is connected to the exploration path 5 via the inspection hole 3a, and an ultra-small camera 10 is inserted into the exploration path 5 to photograph the inside of the sheath 3 (see claim 7 in the claims of Patent Document 1, paragraphs

[0018] to

[0032] of the specification, Figures 1 and 2 of the drawings, etc.).

[0005] Furthermore, as a re-injection method for re-injecting grout into portions of a PC structure that have not been filled with grout, for example, Patent Document 2 discloses a grout refilling method in which, when pressurizing and injecting grout from a grout pressurized injection port 13 using a grout pressurized injection device 20, an endoscope 30 is used that is equipped with a small camera 32 at the tip of an insertion section 31, has an operating device entrance / exit path formed inside the insertion section 31, and has the tip of the operating device entrance / exit path opened at the tip face, and while monitoring the inside of a grout-unfilled cavity 12 through the small camera 32, the tip of the insertion section 31 is inserted through the outlet 14, and grout is pressurized and injected from the grout injection port while evacuating air through the operating device entrance / exit port of the endoscope 30 (see claim 1 in the scope of claims of Patent Document 2, paragraphs

[0019] to

[0036] of the specification, and Figures 1 to 4 of the drawings, etc.).

[0006] However, endoscopes (fiberscopes or videoscopes) are extremely expensive and delicate instruments that were originally developed to look inside the human body, and they have the problem of being easily damaged. Endoscopes for industrial use have a metal-reinforced surface, which improves resistance to damage during insertion, but for small-diameter endoscopes that are inserted into narrow spaces, the method of use may not be sufficient. In industrial use, since the object to be inspected is a rigid body, if excessive force is applied, the force will be applied directly to the endoscope itself, which may cause damage.

[0007] As described in the grout filling confirmation method described in Patent Document 1 and the grout refilling method described in Patent Document 2, when using an endoscope to observe inside the sheath of a PC structure, there is a high risk that it will get caught in narrow gaps between concrete or steel materials and become stuck, and will break if pulled forcefully. In addition, endoscopes are very expensive, and there is also the problem that the damage will be great if they are broken.

[0008] In particular, when an endoscope is used for the grout refilling method described in Patent Document 2, there are problems in that the grout filling status inside the sheath is unclear, and there is a high risk of the endoscope being damaged by the sharp parts newly drilled and opened in the sheath. Therefore, there is a demand for an endoscope-based method for observing inside the sheath that is easy to use and has little risk of damaging the endoscope.

[0009] On the other hand, Patent Document 3 discloses a parent-child endoscope device having an outer sheath which is insertable / removable into a treatment tool insertion channel of a parent scope and has an effective length longer than the overall length of the treatment tool insertion channel, a contrast medium injection tube which is insertable / removable into the outer sheath and has an effective length longer than the overall length of the outer sheath, and a child scope which is insertable / removable into the outer sheath and has an effective length longer than the overall length of the outer sheath (see claim 1 in the claims of Patent Document 3, paragraphs

[0009] to

[0039] of the specification, Figure 4 of the drawings, etc.).

[0010] However, this system was designed to allow observation inside the bile duct etc. after a contrast agent was injected into the bile duct using the main scope, and the secondary scope was then inserted to observe the inside of the bile duct etc., and it was not possible to protect the endoscope from damage when used for observation inside the sheath. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2001-336251 A [Patent Document 2] JP 2014-105527 A [Patent Document 3] JP 2001-190496 A Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been devised in consideration of the above-mentioned problems, and an object of the present invention is to provide an endoscope-based method for observing inside a sheath of a PC structure, which is easy to use and prevents damage to the endoscope when using an endoscope to observe the grout filling status inside the sheath of a PC structure. [Means for solving the problem]

[0013] The method for observing inside a sheath using an endoscope according to claim 1 is a method for observing a grout-filled state inside a sheath of a PC structure using an endoscope, in which a protective member for protecting an insertion part of the endoscope is inserted into the sheath, and the grout-filled state inside the sheath is observed using the endoscope. death, The protective member includes a resin tube and a The restoring force restores the entire protective member to a straight state, ensuring straightness during insertion. The endoscope has a spiral metal wire, and is inserted and removed from the edge portion cut open when the sheath is drilled while being protected by the spiral metal wire.

[0015] Claim 2 The method for observing inside a sheath using an endoscope according to the present invention is characterized in that, in the method for observing inside a sheath using an endoscope according to claim 1, the protective member is inserted into the sheath in advance before the cable of the endoscope is inserted into the protective member.

[0016] Claim 3 The method for observing inside a sheath using an endoscope according to the present invention is 2 In the method for observing inside a sheath using an endoscope according to the above, the protective member is inserted into an introduction tube having a curved tip, and the protective member is guided into the sheath through an observation hole drilled in the PC structure by the curve of the introduction tube.

[0017] Claim 4 The method for observing inside a sheath using an endoscope according to the present invention is 2 or 3In the method for observing inside a sheath using an endoscope according to the above, the protective member is inserted into the sheath in advance, and then air is blown into the protective member.

[0018] Claim 5 The method for observing inside a sheath using an endoscope according to claim 1 is characterized in that, in the method for observing inside a sheath using an endoscope according to claim 1, the protective member has guide means for guiding the tip of the endoscope into a gap between the sheath and the PC steel, and in an endoscope insertion step of inserting the endoscope into the sheath, the endoscope is guided by the guide means and inserted into the gap.

[0019] Claim 6 The method for observing inside a sheath using an endoscope according to claim 1 is characterized in that the protective member has a member that covers the edge portion that is cut open when drilling a hole in the sheath, and when the endoscope is withdrawn from the sheath after observation with the endoscope, the endoscope is withdrawn in a state where the edge portion is covered with the edge covering member. Effect of the Invention

[0025] Claim 1~ 6 According to the present invention, the protective member protects the insertion part of the endoscope, so that the endoscope can be prevented from being damaged when observing the grout filling status inside the sheath of a PC structure using the endoscope. This reduces the risk of the endoscope getting stuck in a narrow gap between concrete or steel material and being unable to be removed, or the risk of the endoscope being damaged by a sharp part newly drilled in the sheath. Furthermore, according to the inventions of claims 1 to 6, the endoscope is inserted and removed from the edge portion cut open when drilling the sheath while being protected by the spiral metal wire. This not only protects the endoscope with the spiral metal wire, but also improves straightness and ease of use due to the spiral metal wire of the protective member, making it possible to insert the endoscope into narrow gaps to observe the grout filling status.

[0027] In particular, claims 2According to the invention, the protective member is inserted into the sheath before the insertion portion of the endoscope is inserted into the protective member, which not only further reduces the risk of damaging the insertion portion of the endoscope, but also shortens the time required to insert the insertion portion of the endoscope. In addition, since the protective member is inexpensive and highly replaceable even if it is damaged, there is no need to worry even if it is handled roughly, and it can be inserted in an extremely short time compared to the time required to insert the insertion portion of the endoscope.

[0028] In particular, claims 3 According to the invention, the protective member can be smoothly guided by the curve of the introduction tube at the point where it is bent into the sheath from the observation hole, which is the most difficult point of insertion, and therefore the cable of the endoscope, which is inserted later, can be inserted in an even shorter time.

[0029] In particular, claims 4 According to the invention, after the protective member is inserted into the sheath in advance, air is blown into the protective member, so that water droplets, dust, dirt, etc. can be blown away with the air to clear the field of view of the endoscope.

[0030] In particular, claims 5 According to the invention, the endoscope is guided by the guide means and inserted into the gap, so that the insertion portion of the endoscope can be inserted in an even shorter time.

[0031] In particular, claims 6 According to the invention, when the endoscope is pulled out from within the sheath, the endoscope is pulled out while the edge portion is covered with a member for covering the edge portion, thereby preventing damage to the endoscope. [Brief description of the drawings]

[0037] [Figure 1] FIG. 1 is a process explanatory diagram showing a hole drilling process of a method for observing inside a sheath using an endoscope according to this embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a protective tube used in the method for observing inside a sheath using an endoscope according to this embodiment. [Diagram 3]FIG. 3 is a side view showing an introduction tube used in the method for observing inside a sheath using an endoscope according to this embodiment, with the introduction tube omitted. [Figure 4] FIG. 4 is a schematic diagram showing a videoscope unit used in the method for observing inside a sheath using an endoscope according to this embodiment. [Diagram 5] FIG. 5 is a photograph showing visible light leaking from a broken portion of an optical fiber. [Figure 6] Figure 6 is a photograph showing the area around the insertion hole of the test specimen into which the PC steel rod was inserted. [Figure 7] Figure 7 is a photograph showing a full view of the test specimen with the PC steel rods inserted. [Figure 8] FIG. 8 is a photograph showing the upper end of the test specimen with the PC steel rod inserted. [Figure 9] FIG. 9 is a photograph showing the vicinity of the arrival point of the test specimen with the PVC pipe inserted. [Figure 10] FIG. 10 is a perspective view mainly showing a protective tube according to the first modification. [Figure 11] FIG. 11 is a vertical sectional view showing the protective tube in use. [Figure 12] FIG. 12 is a perspective view mainly showing a protective tube according to the second modification. [Figure 13] FIG. 13 is a perspective view mainly showing a protective tube according to the third modification. [Figure 14] FIG. 14 is a diagram showing a state in which a protective tube according to Modification 3 is used, in which (a) is a see-through oblique view showing a sheath and an observation hole, and (b) is a vertical cross-sectional view showing a state cut along the sheath. [Figure 15] FIG. 15(a) is a perspective view showing a protective tube according to Modification 4, and FIG. 15(b) is a perspective view showing a protective tube according to a further modification of the protective tube according to Modification 4. As shown in FIG. [Figure 16] FIG. 16 is a perspective view showing a protective tube according to Modification 4 in use with a sheath and an observation hole seen through. [Figure 17] FIG. 17 is a perspective view showing a protective tube according to the fifth modification. [Figure 18] FIG. 18 is an exploded perspective view showing the configuration of a protection tube according to the fifth modification. [Figure 19] FIG. 19 is a schematic cross-sectional view showing a method of using a protective tube according to Modification 5, where (a) shows the time of insertion and (b) shows the time of removal. [Figure 20] FIG. 20 is a perspective view showing a protective tube according to Modification 6, where (a) shows the tip before it is pulled up by the lever, and (b) shows the tip after it has been pulled up by the lever. [Figure 21] FIG. 21 is a perspective view showing a protective member according to Modification 7 with a sheath and an observation hole being seen through. [Figure 22] FIG. 22 is a perspective view showing a protective tube according to Modification 8 with a sheath and an observation hole being seen through. [Figure 23] FIG. 23 is a cross-sectional view taken along the observation hole, showing a state in which the protective tube according to the eighth modification is inserted into the observation hole. [Figure 24] Figure 24 is a diagram explaining the difference in the radius of curvature due to different ways of inserting the endoscope, where (a) shows the case where the endoscope is inserted vertically upward, and (b) shows the case where the endoscope is tilted horizontally and inserted upward. [Diagram 25] FIG. 25 is a perspective view showing a protective tube according to the ninth modification. [Figure 26] FIG. 26 is a cross-sectional view taken along the observation hole, showing a state in which the protective tube according to the ninth modification is inserted into the observation hole. [Figure 27] FIG. 27 is a cross-sectional view taken along the observation hole and showing a state in which the protective tube according to the tenth modification is inserted into the observation hole. [Figure 28] FIG. 28 is an exploded perspective view showing a protective tube according to the tenth modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, an embodiment of an internal sheath observation method using an endoscope according to the present invention will be described in detail with reference to the drawings.

[0039] First, a sheath interior observation method using an endoscope according to an embodiment of the present invention will be described with reference to Figures 1 to 4. In this embodiment, a case will be described in which there is a portion of the sheath of an existing post-tensioned PC structure that is not filled with grout, and the inside of the sheath is observed using an endoscope to grasp the unfilled portion.

[0040] (Identifying areas not filled with grout) First, similarly to the conventional observation method described in Patent Document 2, the sheath observation method using an endoscope according to this embodiment uses non-destructive testing to check whether there are any ungrout-filled sections 3 inside the sheath 2 of an existing PC structure 1, and identifies the ungrout-filled sections 3 (see Figure 1).

[0041] Specifically, non-destructive tests for checking the presence or absence of unfilled grout areas include X-ray transmission method, electromagnetic radar method, broadband ultrasonic method, impact elastic wave method, magnetic exploration method, etc. By performing these non-destructive tests, the unfilled grout areas are identified and the observation holes, injection holes, and discharge holes are determined.

[0042] (Drilling process) Next, as shown in Fig. 1, the method for observing inside a sheath using an endoscope according to this embodiment includes a drilling step for drilling an observation hole H1, an injection hole H2, and a discharge hole H3. Fig. 1 is a process explanatory diagram showing the drilling step of the method for observing inside a sheath using an endoscope according to this embodiment. Of course, the observation hole H1 may also be used as the injection hole H2 or the discharge hole H3, and it goes without saying that only the observation hole H1 may be drilled when only investigation or inspection is to be performed. Reference numeral 4 denotes PC steel 4 that applies prestress to the PC structure 1.

[0043] Specifically, holes are drilled from the surface of the PC structure 1 toward the grout-unfilled portion 3 of the sheath 2 using a drilling machine equipped with a small-diameter (for example, diameter 5 mm to 25 mm) diamond bit or core bit to form the observation hole H1, injection hole H2, and discharge hole H3. Of course, it goes without saying that the holes may be drilled using other drilling means such as a water jet. However, drilling using a drilling machine equipped with a small-diameter diamond bit is preferable because the drilling machine is easy to carry by hand and the drilling time is short.

[0044] (Protective tube insertion process) Next, in the method for observing inside the sheath using the endoscope according to this embodiment, a protective tube insertion step is performed in which a protective tube, which is a protective member that protects the insertion portion of the endoscope, is inserted.

[0045] As shown in Fig. 2, the protective tube 5 used in this step is composed of a resin tube 50 and a spiral steel wire 51, which is a spiral metal wire, fitted inside the resin tube 50. Fig. 2 is a cross-sectional view showing a protective tube used in the method for observing inside a sheath using an endoscope according to this embodiment.

[0046] The resin tube 50 is a resin tube made of a highly wear-resistant resin such as PFA (Tetrafluoroethylene perfluoroalkylvinyl ether copolymer) or PEEK (Poly Ether Ether Ketone), having an outer diameter of 1 / 6 inch (about 1.6 mm), an inner diameter of 1.0 mm, and a length of 4.5 m. Of course, the size of the resin tube is not limited to the example shown, and can be appropriately adopted. For example, the resin tube 50 can be a resin tube having an outer diameter of 3 mm, an inner diameter of 2.6 mm, and a length of 4.5 mm. Of course, the resin tube is not limited to PFA or PEEK, and can be made of other resins as long as it has a certain degree of flexibility and wear resistance.

[0047] In other words, the resin tube 50 is not limited to PFA, and any material can be used as long as it has a certain degree of flexibility that allows it to bend and crush and pass through the gap, and a certain degree of rigidity that allows it to return to its original shape and straighten out when combined with the spiral steel wire 51, and abrasion resistance that prevents it from being damaged even when inserted repeatedly.

[0048] The spiral steel wire 51 is made of a steel wire with a wire diameter of 0.14 mm, processed into a spiral shape with an outer diameter of 2.0 mm and an inner diameter of 1.72 mm, which is stretched and fitted inside the aforementioned resin tube with an inner diameter of 1.0 mm. This spiral steel wire 51 has a function as a spring material to restore the entire protective tube to a straight state by the restoring force of the steel wire, thereby ensuring straightness at the time of insertion. Of course, the size of the spiral steel wire is not limited to the example shown, and can be appropriately adopted. For example, the spiral steel wire 51 may be processed into a spiral shape with a wire diameter of 0.2 mm, an outer diameter of 3.0 mm, and an inner diameter of 2.6 mm, and if necessary, it may be stretched and fitted inside the aforementioned resin tube 50 with an inner diameter of 3.0 mm or less, for example, an inner diameter of 2.6 mm.

[0049] Of course, the diameter of the spiral steel wire 51 can be changed as appropriate, and if the restoring force of the spiral steel wire 51 as a spring material is insufficient and the straightness is insufficient, the restoring force can be adjusted by increasing the diameter of the spiral steel wire 51 or changing the type of steel material. The spiral steel wire 51 may be fitted on the outside of the resin tube 50, or may be inserted into the resin wall of the resin tube to be integrated therewith. In short, the spiral steel wire 51 may be inserted either inside or outside the resin tube 50. In any case, the restoring force of the spiral steel wire 51 can restore the entire protective tube to a straight state, ensuring the straightness at the time of insertion.

[0050] 1, since the observation hole H1 is drilled in the shortest possible distance from the surface of the PC structure 1, it is often perpendicular to the sheath 2 or at an acute angle. For this reason, when inserting the protective tube 5 from the observation hole H1 into the sheath 2, it is necessary to bend the protective tube 5 at a right angle or at an acute angle from the observation hole H1 toward the sheath 2, which makes it the most difficult task to introduce the tip of the flexible protective tube 5 into the tube of the sheath 2.

[0051] Therefore, in the in-sheath observation method using an endoscope according to this embodiment, the introduction tube 6 shown in Fig. 3 is used, and the tip of the protective tube 5 is guided and bent along the tip curve 6a of the introduction tube 6, and introduced into the tube of the sheath 2. Therefore, the protective tube 5 can be smoothly guided into the tube of the sheath 2, and the protective tube 5 can be placed at a predetermined position in a short time. Fig. 3 is a side view showing the introduction tube used in the in-sheath observation method using an endoscope according to this embodiment, with the middle part omitted.

[0052] The introduction pipe 6 is a copper pipe with an inner diameter slightly larger than the outer diameter (about 1.6 mm) of the protective tube 5, and has a gently curved tip curve 6a at its tip, as shown in Fig. 3. The degree of bending of this tip curve 6a is finely adjusted on-site depending on how the protective tube 5 is inserted. Of course, the introduction pipe 6 is not limited to a copper pipe, and may be any metal pipe that is malleable enough to allow fine adjustment of the shape of the tip curve 6a on-site. However, the introduction pipe may be made of resin, and multiple types of pipes with different curvatures of the curve may be prepared and used separately, or the curvature of the curve may be finely adjusted on-site by heating.

[0053] (Compressed air blowing process) Next, in the method for observing inside a sheath using an endoscope according to this embodiment, a compressed air blowing step is performed in which compressed air is blown into the protective tube 5 to blow away obstacles such as water droplets, dust, and dirt.

[0054] Depending on the internal conditions, when the endoscope insertion part 75 or the protective tube 5 is inserted, it is expected that obstacles such as water droplets (moisture), dust, and dirt will adhere to the endoscope insertion part 75 or the protective tube 5, resulting in poor visibility when the endoscope reaches the target position. However, since the protective tube 5 is hollow, it is possible to blow away obstacles such as water droplets, dust, and dirt by pumping air into the protective tube 5, thereby clearing the visibility. Furthermore, when the endoscope insertion part 75 is inserted into the protective tube 5, there is little risk of dirt or dirt adhering again, making it possible to observe with good visibility. Therefore, it is no longer necessary to repeatedly insert and remove the endoscope insertion part 75 until the visibility is clear, and the risk of damaging the endoscope insertion part 75 is further reduced.

[0055] (Endoscope insertion process) Next, in the method for observing inside a sheath using an endoscope according to this embodiment, an endoscope insertion step is performed in which the insertion portion of the endoscope is inserted into the protective tube 5 inserted in the previous protective tube insertion step.

[0056] Fig. 4 is a schematic diagram showing a videoscope unit 7 used in the in-sheath observation method using an endoscope according to this embodiment. As shown in Fig. 4, the videoscope unit 7, which is an endoscope, is an IPLEX TX manufactured by Olympus Corporation, which is composed of an endoscope insertion section 75, an endoscope operation section 70, a monitor section 71, a universal cable 72 connecting these, an operation controller section 73, etc. It is necessary to use a videoscope unit of an appropriate size according to the size of the area to be examined.

[0057] This videoscope unit 7 is an endoscope unit that can display images captured by a video camera using an image sensor (CCD, CMOS, etc.) built into the tip 76 on the tip side of the endoscope insertion section 75 in real time on the monitor section 71. Here, the explanation will be given assuming that the gap is 3 mm or less, and that the outer diameter of the tip of the insertion section is 2.4 mm, making it possible to insert into an extremely narrow gap.

[0058] Of course, the endoscope that can be used in the present invention is not limited to a videoscope, and is not particularly limited as long as it is a means that allows visual observation of the inside of the sheath 2 through a small diameter hole. However, the videoscope unit 7 is preferable because it can display an image on the monitor section 71 in real time, allowing multiple people to confirm the image, and it is easy to record.

[0059] The endoscope operation section 70 of the videoscope unit 7 according to this embodiment has a bending section operation section 74 and is equipped with an endoscope insertion section 75 on the tip side and a tip section 76 having a bending section 77, and the bending section 77 can be freely bent by the bending section operation section 74. The tip section 76 is equipped with the bending section 77, an illumination optical unit 78 that emits light from a light guide fiber guided by an LED illumination unit (not shown) installed inside the endoscope operation section 70, and an objective lens 79.

[0060] In the previous step, the protective tube 5 has already been placed from the observation hole H1 through the inside of the sheath 2 to the ungrouted portion 3. Therefore, in this step, the endoscope insertion portion 75 and the tip portion 76 are simply pushed into the protective tube 5, and since the spiral steel wire 51 with a circular cross section is placed inside the protective tube 5, the endoscope insertion portion 75 can be inserted extremely smoothly.

[0061] Although the protective tube 5 is inserted before the endoscope insertion portion 75, the endoscope insertion portion 75 may be inserted into the sheath with the protective tube 5 fitted thereon, or the tip portion 76 of the endoscope insertion portion 75 may be partially inserted before the protective tube 5. The order of insertion may be changed as appropriate, for example, by inserting the protective tube 5 first, then inserting the endoscope insertion portion 75, and then inserting the endoscope insertion portion 75 further back than the tip of the protective tube 5, and then inserting the protective tube 5 further back. Even in this case, it is clear that the risk of damaging the endoscope insertion portion 75 by the protective tube 5 is reduced.

[0062] (Inside sheath observation) Thereafter, in the method for observing inside the sheath using an endoscope according to this embodiment, a videoscope unit 7 is used to check the ungrouted portions 3 inside the sheath 2 and the deterioration state of the PC steel members inside the sheath 2.

[0063] According to the above-described method for observing inside a sheath using an endoscope according to this embodiment, the tip portion 76 and the endoscope insertion portion 75 are protected by the protective tube 5 in which the spiral steel wire 51, which is a spring material, is fitted inside the resin tube 50, so that it is possible to prevent the endoscope insertion portion 75 and the tip portion 76 from being damaged when observing the grout filling status inside the sheath 2 of the PC structure 1 using the videoscope unit 7. This reduces the risk of the endoscope insertion portion 75 becoming caught in a narrow gap between concrete or steel material and becoming unable to be removed, and of the endoscope insertion portion 75 being damaged by a sharp portion newly drilled and opened in the sheath 2.

[0064] Furthermore, according to the method of observing inside the sheath using the endoscope of this embodiment, the spiral steel wire 51 improves the straightness and ease of use of the protective tube 5, and the endoscope insertion portion 75 can be inserted into narrow gaps to observe the grout filling status.

[0065] Furthermore, according to the method for observing inside the sheath using an endoscope according to this embodiment, the protective tube 5 is inserted into the sheath 2 before the endoscope insertion portion 75 is inserted into the protective tube 5. This not only further reduces the risk of damaging the tip 76 and the endoscope insertion portion 75, but also shortens the time required to insert the endoscope insertion portion 75 into the ungrouted portion 3.

[0066] In addition, according to the internal sheath observation method using an endoscope of this embodiment, when inserting the protective tube 5, there is no need to worry even if it is damaged because it is inexpensive and easily replaceable, and it can be handled roughly, and compared to the internal sheath observation method using a conventional endoscope, it can be inserted in an extremely short time compared to the time required to insert the endoscope insertion portion 75.

[0067] Furthermore, according to the method for observing inside the sheath using the endoscope according to this embodiment, the protective tube 5 can be smoothly guided by the curved tip 6a of the introduction tube 6 at the point where it is bent into the sheath 2 from the observation hole H1, which is the most difficult point for insertion. This allows the endoscope insertion portion 75, which is inserted later, to be inserted in an even shorter time.

[0068] Furthermore, according to the method for observing inside the sheath using the endoscope of this embodiment, by placing the protective tube 5 on the outside of the endoscope insertion portion 75, it becomes possible to carry out the compressed air blowing step described above, and the air can be used to blow away water droplets, dust, dirt, etc., thereby clearing the view.

[0069] <Experiment to confirm disconnection using optical fiber> Next, an experiment to confirm the effect of the present invention will be described. In this experiment, an optical fiber was inserted into the protective tube 5 instead of an endoscope, and visually confirmed whether or not the optical fiber would break even if it was roughly handled.

[0070] Specifically, the above-mentioned protective tube 5 was made of a resin tube 50 made of PFA, and the above-mentioned spiral steel wire 51 was inserted inside to make a prototype tube. Also, to simulate the environment inside the sheath of a PC structure, a test specimen was made by attaching a thin PVC pipe with an inner diameter of 15 mm to a thick PVC pipe with an inner diameter of 38 mm and a length of 3100 mm so that the pipe axis direction was perpendicular to the thick PVC pipe.

[0071] The prototype tube was then inserted into the aforementioned test specimen, and an optical fiber (diameter 0.25 mm) from an optical fiber measuring instrument manufactured by Yokogawa Measurement Corporation was then inserted into the prototype tube and roughly handled to determine whether or not a break occurred in the optical fiber.

[0072] The occurrence of optical fiber breaks was confirmed by using the multi-field tester, an optical fiber measuring device mentioned above, to visualize the tip of the optical fiber and, in the event of a break, detecting visible light leaking from the point of the break in the optical fiber (see Figure 5).

[0073] (Experimental Results) As a result, no breaks were found in the optical fiber even when roughly handled. Therefore, it was determined that the insertion of a protective tube would also prevent damage to the endoscope cable.

[0074] <Protection tube reach experiment> Next, a protective tube reach experiment was carried out to confirm how far the protective tube 5 alone could be inserted into the sheath.

[0075] Specifically, to simulate the environment inside the sheath of a PC structure, a thin transparent vinyl pipe with an inner diameter of 15 mm was attached as an observation hole to a transparent vinyl pipe with an inner diameter of 38 mm and a length of 0.8 m (see Figure 6), and a corroded PC steel rod was inserted. The extent to which the protective tube 5 reached vertically upward, which is an adverse condition, was measured with a tape measure to confirm this (see Figures 7 and 8).

[0076] As a result, the protective tube 5 was able to reach the upper end of the test specimen, that is, up to 0.8 m vertically upward.

[0077] For this reason, as an additional experiment, a similar test specimen having a length of 1.3 m or more was created, and an opaque PVC pipe was inserted in place of the rusted PC steel member to confirm how far the protective tube 5 would reach in the horizontal direction.

[0078] As a result, the limit was 1.2 m, as shown in Figure 9. However, it is considered possible to increase the restoring force of the protective tube 5 and improve the straightness by changing the spiral steel wire 51 inserted as a spring material in the protective tube 5 to one with a larger diameter, or by changing the resin tube 50 from PFA to PEEK.

[0079] [Modification 1 of protective tube] Next, another embodiment of the protective tube (protective member) used in the in-sheath observation method using an endoscope according to the embodiment of the present invention will be described in more detail with reference to Figures 10 and 11. Figure 10 is a perspective view mainly showing a protective tube 8 according to Modification 1, and Figure 11 is a vertical sectional view showing the protective tube 8 according to Modification 1 in use.

[0080] As shown in Figures 10 and 11, the protective tube 8 of variant example 1 includes a resin tube 80, which is a resin tube having flexibility, elasticity, and abrasion resistance, similar to the resin tube 50 described above, and a spiral steel wire 81, similar to the spiral steel wire 51 described above, fitted inside this resin tube 80.

[0081] This resin tube 80 differs from the above-mentioned resin tube 50 in that it has a bent portion 80a, the tip of which is bent when inserted into the sheath 2, as guide means for guiding the tip 76 of the endoscope insertion portion 75 into the gap s between the sheath 2 and the PC steel material 4. Even if this bent portion 80a is crushed straight before insertion, the repulsive force (elastic force) of the resin causes the bent portion 80a to rise up and return to its bent shape.

[0082] 10, the height h1 of the bent portion 80a of the resin tube 80 is set to be larger than the diameter φ1 of the observation hole H1, which is a horizontal hole that intersects with the axial direction of the sheath 2 and is drilled to reach the sheath 2. As shown in Fig. 11, when the bent portion 80a of the resin tube 80 reaches the sheath 2 from the observation hole H1, the bent portion 80a of the resin tube 80 stands up, making it easier to introduce the endoscope insertion portion 75 and the tip portion 76 into the gap s between the sheath 2 and the PC steel material 4.

[0083] As shown in Fig. 10, a notch 80b is formed at the tip of the protective tube 8 by cutting obliquely from the end face toward the side peripheral surface in the longitudinal direction. As shown in Fig. 11, this notch 80b is set so that when the tip of the protective tube 8 abuts against the PC steel 4, the distance e from the inner peripheral surface excluding the notch 80b shown in Fig. 10 is approximately the same distance as the gap s between the sheath 2 and the PC steel 4, but is slightly shorter. Since there is no part on the outer peripheral surface of the PC steel 4 that can be caught, it is desirable to make the overall thickness as thin as possible if the protective tube 8 can protect the sharp edge E1 side at the boundary with the observation hole H1 that cuts through the sheath 2.

[0084] 10 and 11, unlike the protective tube 5 described above, the protective tube 8 includes a cylindrical rigid pipe 82 made of a hard resin or metal tube having no flexibility, which is fitted inside the resin tube 80. The tip of the rigid pipe 82 is connected to the spiral steel wire 81, and the base end of the rigid pipe 82 is fixed to a base 84 of a fixing jig 83.

[0085] 10, the resin tube 80 can be attached and fixed to the endoscope insertion portion 75 by a fixing jig 83. In other words, according to the protective tube 8 of Modification 1, the endoscope insertion portion 75 can be protected by the protective tube 8 while the tip portion 76 can be introduced into the gap s between the sheath 2 and the PC steel material 4, without the need to perform a protective tube insertion step prior to the endoscope insertion step, as in the above-described inside-sheath observation method.

[0086] Next, a method of using the protective tube 8 according to this modified example 1 and a method of observing inside the sheath using the protective tube 8 will be described. Note that only points that differ from the above-described method of observing inside the sheath using an endoscope will be described, and explanations of similar steps will be omitted (the same applies below).

[0087] First, a protective tube insertion step is performed in which the protective tube 8 is inserted into the observation hole H1 that has been drilled so as to intersect with the sheath 2. At this time, as described above, the height h1 of the bent portion 80a is higher than the diameter φ1 of the observation hole H1, so the protective tube 8 is inserted in a state in which the bent portion 80a has been pushed and deformed into a straight shape.

[0088] Thereafter, when the protective tube 8 is pushed in until it reaches the sheath 2, the tip of the resin tube 80 reaches the gap s in the sheath 2 from the observation hole H1, and the bent portion 80a stands up due to the restoring force of the resin tube 80. At this time, the notch 80b fits exactly into the outer circumferential surface of the PC steel material 4, and because the distance e is set to be slightly shorter than the width of the gap s, the inner circumferential surface of the resin tube 80 is located within the sharp edge portion E1 where the sheath 2 is cut open.

[0089] 1, an endoscope insertion step is then performed to insert the endoscope insertion portion 75 into the protective tube 8, and the tip portion 76 and the endoscope insertion portion 75 are further pushed out from the tip of the protective tube 8 to perform the above-mentioned observation inside the sheath. At this time, since the inner circumferential surface of the resin tube 80 is located inside the sharp edge portion E1, it is possible to reduce the risk of the endoscope insertion portion 75 getting caught on the edge portion E1 and being damaged when inserting and pulling out the endoscope insertion portion 75. This makes it possible to extend the service life of the videoscope unit 7.

[0090] By lengthening the spiral steel wire 81, the endoscope insertion part 75 may be advanced further from the resin tube 80 together with the spiral steel wire 81 during the endoscope insertion process. This is because the restoring force of the spiral steel wire 81 can improve the straightness of the endoscope insertion part 75 during insertion.

[0091] [Modification 2 of protective tube] Next, the protective tube 9 according to Modification 2 will be described with reference to Fig. 12. Fig. 12 is a perspective view mainly showing the protective tube 9 according to Modification 2. The only difference between the protective tube 9 according to Modification 2 and the protective tube 8 according to Modification 1 described above is that an outer tube 90 is added, and therefore this point will be mainly described, and the same components are given the same reference numerals and descriptions thereof will be omitted.

[0092] 12, the protective tube 9 according to the second modification includes a resin tube 80, a spiral steel wire 81 (not shown) fitted inside the resin tube 80, a rigid pipe 82, and an outer tube 90 fitted outside the resin tube 80 and capable of being freely inserted and removed (moved forward and backward). Like the rigid pipe 82, the outer tube 90 is a cylindrical tube made of a rigid resin or metal tube that has no flexibility.

[0093] The resin tube 80 of the protective tube 9 also has the bent portion 80a. By attaching the outer tube 90 to the outside of the resin tube 80, the bent portion 80a can be deformed into a straight shape simply by sliding the position of the outer tube 90 along the axial direction of the resin tube 80, and the protective tube insertion process can be performed more quickly and smoothly.

[0094] Also, by simply sliding the position of the outer tube 90 along the axial direction of the resin tube 80, it is possible to adjust the rising condition of the bent portion 80a, facilitating position adjustment of the edge portion E1 and the tip of the resin tube 80. This further reduces the risk of the endoscope insertion portion 75 getting caught on the sharp edge portion E1 and being damaged when inserting and withdrawing the endoscope insertion portion 75.

[0095] [Modification 3 of protective tube] Next, the protective tube 10 according to the modified example 3 will be described with reference to Figs. 13 and 14. Fig. 13 is a perspective view mainly showing the protective tube 10 according to the modified example 3. Fig. 14 is a view showing the protective tube 10 according to the modified example 3 in use, where (a) is a perspective view showing the sheath 2 and the observation hole H1, and (b) is a vertical sectional view showing the state cut along the sheath 2. The protective tube 10 according to the modified example 3 differs from the protective tube 8 according to the modified example 1 described above mainly in that it has a push-out tube 100 as guide means, and therefore this point will be mainly described, and the same components are given the same reference numerals and description will be omitted.

[0096] 13, protective tube 10 according to modification 3 includes resin tube 80 and extruded tube 100, which is a flat member that is fitted into resin tube 80 and can be freely inserted and removed (advanced and retreated). A certain length or the entirety of extruded tube 100 is crushed from the tip to give it a hollow flat shape, and a notch 102 is formed in tip 101, so that one flat side is cut away and eliminated.

[0097] The extrusion tube 100 is a flexible and elastic resin tube, similar to the resin tube 80. However, in order to allow the extrusion tube 100 to be freely inserted into and removed from the resin tube 80, it is preferable that either one or both of the extrusion tube 100 and the resin tube 80 be made of a resin having high peelability and slidability, such as PFA (Tetrafluoroethylene perfluoroalkylvinyl ether copolyte) or PEEK (Poly Ether Ether Ketone).

[0098] As shown in FIG. 14, in the protective tube insertion process for the protective tube 10 of the third modification, the protective tube 10 is inserted in the same manner as the protective tube 8 of the first modification, and then the extrusion tube 100 is further extruded from the tip of the resin tube 80 to extend it.

[0099] At this time, since the extruded tube 100 has a bent flat shape, it is easy to bend in the direction of the flat weak axis, and since a bent portion 80a is formed in the resin tube 80, when the extruded tube 100 is extruded from the tip of the resin tube 80, it is inevitably inserted into the gap s between the sheath 2 and the PC steel material 4.

[0100] Thereafter, when the endoscope insertion step is performed, since the pushable tube 100 has already reached the gap s, the endoscope insertion portion 75 can be extremely smoothly and quickly inserted into the target sheath 2. This completely eliminates the risk of the endoscope insertion portion 75 getting caught on the sharp edge portion E1 and being damaged.

[0101] Furthermore, by using a resin with high releasability and slidability, such as PFA or PEEK, for the extrusion tube 100, the endoscope insertion portion 75 can be inserted and removed more smoothly in a shorter time.

[0102] 13, the wall thickness of the tube excluding the notch 102 remains only on one side of the tip 101 of the extruded tube 100. There may be cases where the gap s is narrow and it is not possible to ensure the wall thickness of both sides of the resin tube 80 + the wall thickness of both sides of the extruded tube 100 + the endoscope insertion portion 75. However, with the protective tube 10 according to Modification 3, the extruded tube 100 is extruded so that only one side of the tip 101 is positioned in a portion that contacts the sharp edge E1, allowing the endoscope insertion portion 75 to be inserted and removed. Therefore, damage to the endoscope insertion portion 75 can be prevented in this respect as well.

[0103] [Modification 4 of protective tube] Next, the protective tube 11 according to Modification 4 will be described with reference to Fig. 15 and Fig. 16. Fig. 15(a) is a perspective view showing the protective tube 11 according to Modification 4, and Fig. 15(b) is a perspective view showing a protective tube 11' according to a further modification of the protective tube 11 according to Modification 4. Fig. 16 is a see-through perspective view showing the protective tube 11 according to Modification 4 in use, with the sheath 2 and observation hole H1 seen through.

[0104] The protective tube 11 according to the fourth modification includes a resin tube 110 made of resin having flexibility and elasticity similar to the resin tube 80, and a spiral steel wire 81 (not shown) fitted inside the resin tube 110.

[0105] As shown in Fig. 15(a), the resin tube 110 has an upper surface removed portion 110a at the tip, which is formed by cutting out and removing the upper surface (one side from the central axis) as a guide means. A V-shaped groove 110b is formed at the end (tip) of the removed upper surface of the upper surface removed portion 110a. However, the groove 110b is not limited to the V-shape shown in the figure, and may be a groove cut in an arc shape or a rectangle. In short, the shape of the groove 110b may be any shape that can be pushed open by the tip portion 76 to secure a space for inserting the endoscope insertion portion 75 according to the size of the endoscope insertion portion 75.

[0106] 16, in the protective tube insertion step, the protective tube 11 according to Modification 4 is inserted through the observation hole H1 until the tip of the resin tube 110 abuts against the PC steel 4. Then, when the protective tube 11 is pushed further in, due to the presence of the top surface removed portion 110a, the tip of the resin tube 110 is bent along the PC steel 4 as shown in FIG.

[0107] Thereafter, in the endoscope insertion step, endoscope insertion portion 75 is inserted. At this time, not only does the presence of groove 110b make it easy for endoscope insertion portion 75 and tip portion 76 to rise upward, but the presence of upper surface removed portion 110a along PC steel material 4 also makes it easy to insert endoscope insertion portion 75 further in.

[0108] Also, when the endoscope insertion portion 75 is pulled out, the presence of the spiral steel wire 81 can reduce the risk of the endoscope insertion portion 75 getting caught on the edge portion E1 and being damaged.

[0109] As shown in FIG. 15(b), the protective tube 11 in accordance with variant example 4 may be a resin tube 110' (protective tube 11') having a slit 110c formed along the upper surface of the upper surface removed portion 110a, so that the upper surface portion having the groove 110b is open and behaves differently from the upper surface removed portion 110a.

[0110] With this configuration, in the protective tube insertion step, not only is the upper surface removed portion 110a of the protective tube 11' bent along the PC steel 4, but by further pushing the resin tube 110', the upper surface portion with the recessed groove 110b is also partially bent along the PC steel 4. Therefore, according to the protective tube 11', the upper surface portion with the recessed groove 110b covers the above-mentioned sharp edge portion E1, making it possible to prevent damage to the endoscope insertion portion 75 during insertion and removal.

[0111] In addition, by using the resin tubes 110, 110' of a resin with high releasability and slidability such as PFA or PEEK for the protective tube 11 and the protective tube 11', the endoscope insertion portion 75 can be inserted and removed more smoothly in a short time.

[0112] [Modification 5 of protective tube] Next, the protective tube 12 according to Modification 5 will be described with reference to Fig. 17 to Fig. 19. Fig. 17 is a perspective view showing the protective tube 12 according to Modification 5, and Fig. 18 is an exploded perspective view showing the configuration of the protective tube 12 according to Modification 5.

[0113] 17, the protective tube 12 according to the fifth modification is a tube with a double-tube structure that is mainly provided with an outer tube 120 and an inner tube 121 and is configured to be freely slidable relative to each other and can be freely inserted and removed. In addition, a truncated cone-shaped fixing member 122 is attached to the outer tube 120 to be inserted into and fixed in the observation hole H1.

[0114] (Outer tube) 18, the outer tube 120 is composed of a flexible section 123 located at the tip and made of a flexible, highly elastic resin, and a cylindrical rigid section 124 located at the rear end and made of a hard resin or the like that has no flexibility. A ring-shaped handle section 125 is fitted to the rear end of the rigid section 124. This makes it easy to move the handle section 125 back and forth relative to the inner tube 121 and to rotate the protective tube 12 within the observation hole H1.

[0115] An upper surface removed portion 123a is formed by cutting out and removing the upper surface (one side from the central axis) at the tip of this flexible portion 123. Also, as shown in Fig. 18, the lower surface of this upper surface removed portion 123a is a curved surface that is provided as a guide means and curls slightly upward (towards the notch) as it approaches the tip.

[0116] As shown in FIG. 18, a long hole 124a is formed at the rear end of the rigid portion 124 of the outer tube 120 to allow a fixing screw 129 to be inserted therethrough to allow the inner tube 121 to freely slide (move back and forth) relative to the outer tube 120.

[0117] (Inner tube) 18, the inner tube 121 is also composed of a flexible section 126 located at the tip end and made of a highly flexible resin, and a cylindrical rigid section 127 located at the rear end and made of a hard resin or the like that has no flexibility. A cylindrical handle section 128 is connected to the rear end of the rigid section 127.

[0118] A bottom surface removed portion 126a is formed by cutting out and removing the surface at the tip (one side from the central axis) of this flexible portion 126. Also, as shown in Fig. 18, the upper surface of this bottom surface removed portion 126a is curved and curls slightly upward (to the opposite side from the notch) as it approaches the tip.

[0119] 18, a female threaded portion 127a for fastening a fixing screw 129 is formed at the rear end of the rigid portion 127 of the inner tube 121. This is for fixing the fixing screw 129 to the inner tube 121 via the long hole 124a. As a result, the long hole 124a allows the outer tube 120 to freely slide relative to the inner tube 121 (advance and retreat), while restricting the relative rotational movement of the outer tube 120 and the inner tube 121. Therefore, even if the protective tube 12 is rotated within the observation hole H1, the positional relationship between the upper surface removed portion 123a and the lower surface removed portion 126a does not change (see FIG. 17), but the relative sliding movement (advance and retreat) is free.

[0120] Next, a method of using the protective tube 12 according to Modification 5 and a method of observing inside the sheath using the protective tube 12 will be described with reference to Fig. 19. Fig. 19 is a schematic cross-sectional view showing a method of using the protective tube 12 according to Modification 5, where (a) shows the protective tube 12 when inserted and (b) shows the protective tube 12 when removed.

[0121] In the protective tube insertion step, the protective tube 12 according to Modification 5 is inserted through the observation hole H1 until the top surface removed portion 123a, which is the tip of the outer tube 120, abuts against the PC steel 4, and is fixed to the observation hole H1 with the fixing member 122. Thereafter, the outer tube 120 is further advanced and inserted until the top surface removed portion 123a rises up along the PC steel 4 due to the curve of the underside of the top surface removed portion 123a, as shown in FIG.

[0122] Then, in the endoscope insertion step, the endoscope insertion portion 75 is inserted. At this time, due to the presence of the upper surface removed portion 123a, the tip portion 76 of the endoscope insertion portion 75 can easily rise upward along the prestressing steel material 4, and the endoscope insertion portion 75 can be easily inserted into the gap s between the prestressing steel material 4 and the sheath 2 in a short time.

[0123] Thereafter, when the endoscope insertion portion 75 is to be removed after observing inside the sheath, the outer tube 120 is retracted and the inner tube 121 is advanced instead. Then, as shown in FIG. 19(b), the edge portion E1 is covered by the lower surface removed portion 126a of the inner tube 121. At this time, since the upper surface of the lower surface removed portion 126a is a curved surface that curls slightly upward toward the tip, when the lower surface removed portion 126a passes the edge portion E1 and reaches the gap s, it rises according to its tendency, so that the sharp edge portion E1 can be covered by the inner tube 121. Therefore, it is possible to reliably prevent the endoscope insertion portion 75 from being damaged when it is pulled out.

[0124] [Modification 6 of protective tube] Next, the protective tube 13 according to Modification 6 will be described with reference to Fig. 20. Fig. 20 is a perspective view showing the protective tube 13 according to Modification 6, in which (a) shows the state before the tip is pulled up by the lever, and (b) shows the state after the tip has been pulled up by the lever.

[0125] 20(a), the protective tube 13 according to the sixth modification mainly includes an outer tube 130 having a rectangular cross section, and a slide bar 131 made of a single flexible plate material that can slide freely within the outer tube 130. Therefore, in the protective tube 13, the slide bar 131 is slidable relative to the outer tube 130.

[0126] (outer tube) The outer tube 130 is a rectangular, flat, rectangular, rectangular tubular member with a longitudinal direction, which is thin in the vertical direction and made of a hard resin or metal that has no flexibility.

[0127] The rear end of the outer tube 130 is formed with a long hole 130a that is long in the longitudinal direction, through which a protruding lever, which will be described later, is inserted.

[0128] (Slide bar) The slide bar 131 is a flat member provided as a guide means, and is a member folded in half from a strip-shaped plate or sheet material made of flexible resin, metal, or the like.

[0129] The tip of this slide bar 131 is a plate or sheet material folded in half, and an endoscope hole 131a through which the endoscope insertion portion 75 and tip portion 76 are inserted is formed in the folded portion.

[0130] A protruding lever 131b for sliding the slide bar 131 is provided on the upper surface of the rear end of the slide bar 131.

[0131] In the protective tube insertion process of the protective tube 13 according to the sixth modification, the protective tube 13 is inserted through the observation hole H1 and pushed in until the folded portion, which is the tip of the slide bar 131, abuts against the PC steel material 4.

[0132] Thereafter, the protruding lever 131b at the rear end of the slide bar 131 is pulled backward to shift the upper plate of the folded slide bar 131, thereby lifting the tip of the slide bar 131 upward as shown in Fig. 20(a). This makes it easier to insert the endoscope insertion section 75 into the gap s between the PC steel material 4 and the sheath 2, and the endoscope insertion process can be completed easily and in a short time.

[0133] Of course, the protective tube insertion step and the endoscope insertion step may be performed simultaneously, and the protective tube 13 may be inserted into the observation hole H1 with the endoscope insertion portion 75 and the tip portion 76 inserted into the endoscope hole 131a.

[0134] According to the protective tube 13 of variant example 6, there are upper and lower plates of the bifold slide bar 131 on either side of the endoscope insertion portion 75, so there is no risk of the endoscope insertion portion 75 coming into contact with and rubbing against the surrounding edge portion E1, the PC steel material 4, or the sheath 2, and wear on the endoscope insertion portion 75 of an expensive endoscope can be kept to a minimum.

[0135] [Modification 7 of the protective tube (protective member)] Next, a protective tube (protective member) 14 according to Modification 7 will be described with reference to Fig. 21. However, since the protective tube according to Modification 7 is not tubular, hereinafter it will be referred to as protective member 14. Fig. 21 is a see-through perspective view showing protective member 14 according to Modification 7 with the sheath 2 and observation hole H1 seen through.

[0136] 21, the protective member 14 is composed of a lower plate 140, an upper plate 141, etc. The lower plate 140 and the upper plate 141 are plate materials made of hard resin, metal, etc., and the inner surfaces (the upper surface of the lower plate 140 and the lower surface of the upper plate 141 in the illustrated state) through which the endoscope insertion portion 75 is inserted are formed in an arc shape corresponding to the cross-sectional shape of the endoscope insertion portion 75 so that the endoscope insertion portion 75 is sandwiched between the lower plate 140 and the upper plate 141.

[0137] At the tip of the lower plate 140, a curved surface portion 140a is formed as a guide means, curling upward (towards the endoscope insertion portion 75) as it approaches the tip.

[0138] At the tip of the upper plate 141, a notch 141a is formed which is cut in an arc shape corresponding to the cross-sectional shape of the endoscope insertion portion 75.

[0139] The method of using the protective member 14 relating to variant example 7 is to insert the lower plate 140 through the observation hole H1 as a protective tube insertion step, and then to insert the endoscope insertion portion 75 while guiding it along the arc-shaped curved shape and curved portion 140a of the upper surface of the lower plate 140 as an endoscope insertion step.

[0140] When removing the endoscope insertion portion 75 after observing inside the sheath, the protective member 14 first pulls out the lower plate 140, inserts the upper plate 141 through the observation hole H1, and removes the endoscope insertion portion 75 while pressing the edge portion E1 side of the endoscope insertion portion 75 with the notch portion 141a of the upper plate 141. Of course, it goes without saying that if there is a margin in the gap s between the PC steel material 4 and the sheath 2, the lower plate 140 may not be pulled out, but may be left in place and the upper plate 141 may be inserted and pressed with the notch portion 141a of the upper plate 141.

[0141] According to the protective member 14 of variant example 7, the endoscope insertion portion 75 is inserted while being guided by the curved portion 140a of the lower plate 140, so that the endoscope insertion portion 75 can be easily inserted into the narrow gap s between the PC steel 4 and the sheath 2 in a short time.

[0142] Furthermore, according to the protective member 14, even when the endoscope insertion portion 75 is pulled out, the endoscope insertion portion 75 is pulled out while being pressed against the edge portion E1 side by the cutout portion 141a, thereby preventing wear and tear on the endoscope insertion portion 75 of an expensive endoscope.

[0143] [Variation 8 of protective tube] Next, the protective tube 15 according to Modification 8 will be described with reference to Fig. 22 and Fig. 23. Fig. 22 is a see-through perspective view showing the protective tube 15 according to Modification 8 with the sheath 2 and the observation hole H1 seen through, and Fig. 23 is a cross-sectional view showing the protective tube 15 according to Modification 8 inserted into the observation hole H1, cut along the observation hole H1.

[0144] 22 and 23, the protective tube 15 is composed of a fixing tube 150 for fixing to the observation hole H1, and an insertion tube 151 which is a guide means fitted into the fixing tube 150 and rotatable about its axis. The fixing tube 150 and the insertion tube 151 are rotatably connected to each other by a connecting portion 153.

[0145] The fixing tube 150 has a cylindrical base with an outer diameter slightly smaller than that of the observation hole H1, and a ring-shaped flange 150a protrudes from its outer periphery. This flange 150a has the function of fixing the protective tube 15 by abutting against the edge of the outer surface of the observation hole H1, as shown in Fig. 23.

[0146] The insertion tube 151 is a tube having an outer diameter approximately the same as the inner diameter of the fixing tube 150, and has a notch 151a at its tip, with the upper half cut away from the axis. The length L1 from the tip of this notch 151a is set to be slightly longer than the gap s between the PC steel material 4 and the sheath 2.

[0147] A ring-shaped handle 152 is fixed by a fixing screw N1 to the rear end of the insertion tube 151. A cylindrical front end tube portion 152a protrudes from the ring-shaped handle 152, and a ring-shaped ring groove 152b is formed in the front end tube portion 152a and goes around the front end tube portion 152a.

[0148] A pin P1 is inserted into the ring groove 152b from the outside of the fixing tube 150 and comes into contact with the ring groove 152b, thereby forming a connecting portion 153 that connects the fixing tube 150 and the insertion tube 151.

[0149] In the protective tube insertion process, the protective tube 15 of variant example 8 is first inserted into the observation hole H1 and advanced until the flange 150a of the fixing tube 150 abuts against the edge of the outer surface of the observation hole H1, thereby fixing the fixing tube 150 to the observation hole H1.

[0150] 23, the insertion pipe 151 is advanced until the tip of the insertion pipe 151 abuts against the PC steel material 4. Then, the handle 152 is fixed with the fixing screw N1 according to the notch 151a. The position of the fixing screw N1 is aligned with the notch 151a.

[0151] Then, by turning the handle 152, the notch 151a is aligned while watching the position of the fixing screw N1. At this time, the notch 151a is made to face diagonally upward. In this state, the endoscope insertion portion 75 is inserted from the notch 151a, and when the tip portion 76 protrudes slightly, the insertion tube 151 is rotated to push the tip portion 76 into the gap s between the PC steel material 4 and the sheath 2 using the notch 151a.

[0152] Figure 24 is a diagram explaining the difference in the radius of curvature due to different ways of inserting the endoscope, where (a) shows the case where the endoscope is inserted vertically upward, and (b) shows the case where the endoscope is tilted horizontally and inserted upward.

[0153] As shown in Fig. 24(a), if the curvature is R1 when the tip portion 76 is lifted vertically, as shown in Fig. 24(b), the curvature is R2 when the tip portion 76 is tilted horizontally and inserted upward. At this time, R2>R1, and inserting the endoscope insertion portion 75 as described above reduces the load on the endoscope insertion portion 75, and the endoscope insertion portion 75 and the tip portion 76 can be smoothly inserted into the gap s between the PC steel member 4 and the sheath 2. Therefore, with the protective tube 15 of Modification 8, the endoscope insertion portion 75 can be easily inserted into the narrow gap s between the PC steel member 4 and the sheath 2 in a short time.

[0154] Conversely, when the endoscope insertion portion 75 is pulled out, the insertion tube 151 is rotated to adjust the position of the notch 151a according to the position of the endoscope insertion portion 75, making it easier to pull out. Therefore, according to the protective tube 15 of Modification 8, wear on the endoscope insertion portion 75 can be prevented even when the endoscope insertion portion 75 is pulled out.

[0155] [Modification 9 of the protective tube] Next, the protective tube 16 according to Modification 9 will be described with reference to Fig. 25 and Fig. 26. Fig. 25 is a perspective view showing the protective tube 16 according to Modification 9, and Fig. 26 is a cross-sectional view showing the protective tube 16 according to Modification 9 inserted into the observation hole H1, taken along the observation hole H1.

[0156] As shown in Figs. 25 and 26, the protective tube 16 is a tube having a double tube structure including an outer tube 160 and an inner tube 161 which are slidably inserted and removed relative to each other.

[0157] (Outer tube) As shown in FIG. 25, outer tube 160 is a tube made of a flexible, elastic resin, and has an expanded diameter portion 160a at its tip which is cut open like a petal and serves as a guide means.

[0158] Additionally, outer tube 160 has a slit 160b formed by cutting the outer circumference of the tube linearly along the axial direction.

[0159] (Inner tube) The inner tube 161 is a tube having an outer diameter that fits into the outer tube 160, and does not need to be particularly flexible, pliable, or elastic. In addition, if the observation hole H1 is short and the outer tube 160 alone reaches the sheath 2, it does not need to be provided.

[0160] 26, in the protective tube insertion step for the protective tube 16 according to the 9th modification, the outer tube 160 is inserted through an observation hole H1 having an inner diameter substantially the same as the outer diameter of the outer tube 160. When the outer tube 160 reaches the gap s in the sheath 2, the elasticity of the outer tube 160 opens the expanded diameter portion 160a, and the sheath 2 comes to cover the sharp edge portion E1 that was cut when the observation hole H1 was drilled.

[0161] At this time, since a slit 160b is formed in the outer tube 160, even when the outer tube 160 is inserted through the observation hole H1, which has an inner diameter approximately the same as the outer diameter of the outer tube 160, the expanded diameter portion 160a can be smoothly passed through the observation hole H1.

[0162] Thereafter, when the endoscope insertion portion 75 is inserted during the endoscope insertion process, and when the endoscope insertion portion 75 is removed after observing inside the sheath, the elastic expanded diameter portion 160a covers the edge portion E1, so there is little risk of damaging the endoscope insertion portion 75.

[0163] [Modification 10 of the protective tube] Next, the protective tube 17 according to Modification 10 will be described with reference to Fig. 27 and Fig. 28. Fig. 27 is a cross-sectional view showing the protective tube 17 according to Modification 10 inserted into the observation hole H1, taken along the observation hole H1, and Fig. 28 is an exploded perspective view showing the protective tube 17 according to Modification 10.

[0164] As shown in Figs. 27 and 28, the protective tube 17 according to the tenth modification is composed of a tube body 170, a tip adapter 171 detachably attached to the tip of the tube body 170, and the like.

[0165] The tube body 170 is composed of an outer tube 173 which is a cylinder having a diameter approximately the same as that of the observation hole H1, and an inner tube 174 which has a smaller diameter than that of the outer tube 173 and is inserted eccentrically into the outer tube 173, and the outer tube 173 and inner tube 174 are connected by a metal tip nozzle 172.

[0166] The tip adaptor 171 is provided with a guide slope 171a, which is an inclined surface that is provided as a guide means and gently curves upward toward the tip, guiding the tip portion 76. An opening 171b through which the endoscope insertion portion 75 is inserted is formed on the upper surface of the tip adaptor 171. The surface of the tip adaptor 171 on which the opening 171b is provided is set back so that a distance is taken from the upper end of the tube main body 170 when the tip adaptor 171 is attached.

[0167] In addition, tip adapters 171 with different inclination angles of the guide slopes 171a and different sizes of the openings 171b are prepared according to the size of the gap s between the sheath 2, into which the endoscope insertion portion 75 is inserted, and the PC steel material 4, the shapes of the endoscope insertion portion 75 and the tip portion 76, etc., and are used by replacing them as appropriate.

[0168] As shown in Figure 27, in the protective tube insertion process for the protective tube 17 of variant example 10, the protective tube 17 is inserted through the observation hole H1 and the tip adapter 171 attached to the tip of the tube body 170 is abutted against the PC steel material 4.

[0169] Thereafter, in the endoscope insertion step, the endoscope insertion portion 75 is inserted through the opening 171b of the tip adaptor 171 into the gap s between the sheath 2 and the PC steel material 4. At this time, since the tip adaptor 171 is formed with the aforementioned guide slope 171a, the endoscope insertion portion 75 and the tip portion 76 can be guided along the guide slope 171a and introduced into the gap s. Therefore, the protective tube 17 of Modification 10 can improve the working efficiency in the endoscope insertion step.

[0170] Although the in-sheath observation method using an endoscope according to the embodiment of the present invention has been described in detail above, the above-mentioned and illustrated embodiments are merely specific embodiments for carrying out the present invention, and therefore the technical scope of the present invention should not be interpreted as being limited by them.

[0171] In particular, the case where the sheath 2 and the PC steel 4 are inserted vertically has been described as an example, but the present invention is not limited to this case. The case where the endoscope insertion portion 75 is inserted vertically upward into a narrow gap through which the sheath 2 and the PC steel 4 are inserted vertically is the most difficult case for inserting the endoscope insertion portion 75 into the gap, and therefore this case has been merely illustrated. [Explanation of symbols]

[0172] 1:PC structure 2: Sheath 3: Ungrouted area 4:PC steel material E1: Edge section s: gap 5, 8 to 17: Protective tube (protective material) 50,80: Resin tube 51,81: Spiral steel wire (spiral metal wire) 6:Introduction tube 6a: Tip curve 7: Videoscope unit (endoscope) 70: Endoscope operation unit 71: Monitor section 72: Universal cable (cable) 73: Operation controller section 74: Bending section operation section 75: Endoscope insertion part 76:Tip 77: Curved section 78: LED lighting 79: Objective lens 80a: Bent section 80b: Notch 82: Rigid pipe 83: Fixture 84: Cap 90:Outer tube 100: Extruded tube 101:Tip 102: Notch 110,110': Resin tube 110a: Top surface removal part 110b: Concave groove 110c: Slit 120: Outer tube 121: Inner tube 122: Fixing member 123: Flexible part 123a: Top surface removal part 124: Rigid section 124a: Long hole 125: Handle 126: Flexible part 126a: Lower surface removal part 127: Rigid section 127a: Female thread 128: Handle 129: Fixing screw 130:Outer tube 130a: Long hole 131: Slide bar 131a: Endoscope hole 131b: Protruding lever 140: Lower board 140a: Curved part 141: Upper board 141a: Notch 150: Fixing tube 150a: flange 151: Insertion tube 151a: Notch 152: Handle 152a: Front end cylinder part 152b: Ring groove 153:Connection part 160: Outer tube 160a: Expanded diameter part 160b: Slit 161: Inner tube 170: Tube body 171: Tip adapter 171a: Guide slope 171b:Aperture 172: Tip cap 173: Outer tube 174: Inner tube H1: Observation hole H2: Injection hole H3: Discharge hole N1: Fixing screw

Claims

1. A method for observing a grout filling condition in a sheath of a PC structure using an endoscope, comprising: A protective member for protecting an insertion portion of the endoscope is inserted into the sheath, and a grout filling state in the sheath is observed using the endoscope; The protective member has a resin tube and a spiral metal wire that is inserted into the resin tube and restores the entire protective member to a straight shape by a restoring force, thereby ensuring linearity during insertion. The endoscope is inserted and removed while being protected by the spiral metal wire from the edge portion cut open when the sheath is drilled. A method for observing inside a sheath using an endoscope, comprising:

2. The protective member is inserted into the sheath before the insertion portion of the endoscope is inserted into the protective member.

2. A method for observing inside a sheath using an endoscope according to claim 1.

3. The protective member is inserted into an introduction tube having a curved tip, and the curve of the introduction tube guides the protective member into the sheath through an observation hole drilled in the PC structure.

3. A method for observing inside a sheath using an endoscope according to claim 2.

4. The protective member is inserted into the sheath in advance, and then air is blown into the protective member.

4. A method for observing inside a sheath using an endoscope according to claim 2 or 3.

5. the protective member has a guide means for guiding the tip portion of the endoscope into a gap between the sheath and the PC steel material, In the endoscope inserting step of inserting the endoscope into the sheath, the endoscope is guided by the guide means and inserted into the gap.

2. A method for observing inside a sheath using an endoscope according to claim 1.

6. The protective member has a member for covering an edge portion cut open when the sheath is drilled, When the endoscope is removed from the sheath after observation with the endoscope, the endoscope is removed while the edge portion is covered with a member for covering the edge portion.

2. A method for observing inside a sheath using an endoscope according to claim 1.

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