JP4402686B2 - Tube deterioration core sampler and sample core collection method - Google Patents

Description

  The present invention makes it possible to collect from the inside of a pipe a sample for predicting the deterioration of the reinforcing bar and concrete of a concrete pipe reinforced with a reinforcing bar such as a PC pipe or a fume pipe used in a pipe water channel, for example. The present invention relates to a pipe deterioration core sampler and a method for collecting the sample core.

  Conventionally, concrete pipes reinforced with reinforcing bars such as PC pipes and fume pipes are used for pipes such as agricultural water supply, sewerage, and industrial water supply. PC pipes are reinforced concrete pipes (prestressed concrete pipes) in which PC steel wires are wound in the circumferential direction around core concrete pipes that are prestressed by tensioning PC steel wires in the longitudinal direction. This is a reinforced concrete pipe in which a concrete made by centrifugal force is applied to a cage made of steel bars and circumferential reinforcing bars.

  In the PC pipe, mortar is sprayed on the PC steel wire wound in the circumferential direction to cover the PC steel wire to prevent its corrosion. The main cause of corrosion rupture of PC steel wire is attributed to the deterioration of the cover coat mortar on the outer surface of the PC pipe. The cause of this deterioration is considered to be due to the neutralization of the cover coat mortar and the occurrence of cracks. It has been.

  Such cover coat mortar is thin with 2cm in PC tube products before May 1974, and since it is sprayed, there are many variations in thickness, and many of those with less than 2cm have been confirmed. However, in products after 1978, the thickness of the cover coat mortar is 2.5 cm in accordance with JIS standards.

  The neutralization prediction formula currently publicly known is based on research results on concrete, and the predicted value varies greatly depending on the water cement ratio (hereinafter referred to as “W / C”) and the presence or absence of an admixture.

  When Kishitani formula is used as the neutralization prediction formula, the neutralization depth is 15.9 mm in 35 years, the neutralization depth is 20.0 mm in 60 years, and it is medium in 35 years. The carbonization reaches the position of the PC steel wire, and the entire cover coat mortar layer is neutralized after 60 years (cover coat mortar thickness: 20 mm, PC steel wire: φ4 mm, covering: 16 mm). Therefore, in a PC tube having a cover coat mortar thickness of 2 cm, it is necessary to stop the progress of neutralization or re-alkaliize by 35 years.

  Under such circumstances, in order to investigate the deterioration of the cover coat mortar of the PC pipe, the buried PC pipe is dug, and the cover coat mortar is visually checked for cracks and neutralization. Neutralization test by stripping mortar and visual observation of steel corrosion.

  However, the use form of the land has changed around the buried PC pipe, such as being converted into residential land, and it has become difficult year after year to dig out the PC pipe. On the other hand, test sites are prone to subsequent subsidence, and it is difficult to obtain consent from the land owners such as public roads and private land. For this reason, the number of test sites is limited, and it is necessary to evaluate the deterioration state of the PC pipe channel in units of several kilometers at a single location from a small number of test survey data, and there is a concern that the accuracy of deterioration prediction is reduced. For this reason, it is required to collect the core of the cover mortar from the inside of the PC tube and investigate the neutralization depth.

  Also, in the case of fume pipes used in sewage pipes, corrosion on the walls of the sewage pipes does not occur uniformly, such as air flow, sulfuric acid flow along the pipe wall and mixing with water. It is known that pipe surface corrosion progresses. Even in such a fume pipe, it is required to collect a concrete core from the pipe and investigate a corrosion depth and a sulfur penetration depth.

  By the way, there are the following proposals for concrete boring and core specimen collection methods. In the example shown in Japanese Patent Laid-Open No. 10-293091, a plurality of small diameter columnar bodies having a diameter of 15 mm to 30 mm are sampled from a concrete structure with a portable handy core drill, and the average of the compression test is performed using the small diameter columnar bodies as specimens. A concrete strength estimation method for estimating the strength of concrete is disclosed (Patent Document 1).

  In addition, in the example shown in Japanese Patent Laid-Open No. 7-120361, an apparatus used for extracting a core from a solidified body obtained by solidifying a radioactive waste with a solidifying material, the tip portion for extracting the core from the solidified body There is shown a core extracting device including a cutting means including a cylindrical body having a blade-shaped portion and a cooling means for suppressing the influence of heat generated during core cutting by the cutting means (Patent Literature). 2).

Further, in the example shown in JP 2004-50664 A, by using a drilling tube of a core boring machine, by drilling a plurality of boreholes partially overlapping each other in a large section concrete in a row, In the method of cutting concrete, a guide plate installed at the upper part of the preceding boring hole, a guide rod that passes through the guide plate and can be raised and lowered into the preceding boring hole, and is inserted in a non-rotating state, and a lower part of the guide rod A connecting pipe that is coaxially connected to the outer periphery and connected to the lower end of the drilling tube so as to be parallel and relatively rotatable with the lower end of the drilling tube, and is arranged radially on the outer periphery of the roller support pipe and along the inner wall of the preceding borehole A guide jig device for a core boring machine having a plurality of rolling guide rollers is disclosed (Patent Document 3).
JP 10-293091 A (Patent No. 3067016) JP-A-7-120361 JP 2004-50664 A

  However, the conventional boring machines and core extraction methods as shown in Patent Documents 1 to 3 above can be applied as they are when, for example, the core is extracted from the inside of a PC tube or a fume tube having an inner diameter of 900 mm to 2000 mm. Moreover, since the inner diameter of the manhole, which is the entrance to the PC tube or the fume tube, is 600 mm, the boring machine needs to be portable and there is much room for improvement.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide a pipe deteriorated core sampler and a core collecting method capable of extracting a sample core from the inside of a reinforced concrete pipe such as a PC pipe or a fume pipe. And

In order to achieve the above object, the pipe deteriorated core sampler of the present invention includes a core drill for drilling a reinforced concrete pipe from the inside at a position between a longitudinal bar and a horizontal bar, and a parallel drill at a position corresponding to a vertex of a parallelogram. Four cores projecting with the same projection amount in parallel with the central axis perpendicular to the center of gravity of the quadrilateral, and the four cores are brought into contact with the inner wall of the tube, thereby allowing the core drill to The core drill is positioned so as to be positioned on a diameter, and is provided with a base mounted movably along the central axis.

  According to the present invention, the support base for forming the through hole through which the core bit of the core drill passes on the central axis of the base and for supporting the core drill movably on the central axis above the base. Can be provided.

  When taking a sample core from the inside of a reinforced concrete pipe, it is necessary to take the sample at a right angle to the pipe. In the present invention, the core drill is made to contact the inner wall of the pipe by bringing the four projections of the base into contact with the inner wall of the pipe. Since it can be easily positioned so as to lie on the line, the sample core can be easily taken at a right angle from the tube.

  In addition, the core drill is disposed offset with respect to the central axis of the base, and the main body of the column is fixed on the central axis of the base, and the inner wall of the reinforced concrete pipe on the opposite side to the base It is possible to provide a support column in which a pad in pressure contact with the main body of the support column is disposed so as to be movable back and forth in the axial direction. According to this, the core sampler in which the core drill is positioned can be held in the pipe by pressing the pad of the column to the inner wall of the pipe.

  In addition, a lifting block is provided movably in the axial direction of the column with respect to the main body of the column, and a bracket is provided movably on a longitudinal line of the reinforced concrete pipe passing through the central axis with respect to the lifting block, The core drill can be detachably attached to the bracket. A metal sensor for detecting a reinforcing bar of the reinforced concrete pipe can be provided, and the metal sensor and the core drill can be selectively mounted on the bracket.

According to this, since the core drill can be moved in the longitudinal direction of the tube, a plurality of holes overlapping in the longitudinal direction of the tube are drilled without resetting the core sampler in the tube, so that the length for detecting the horizontal muscles is increased. can form a hole, by further attaching a metal sensor in place of the core drill, it is also possible to detect the position of the lateral stripes. If the elevating block is configured to be movable up and down by a screw rod mechanism or the like, the core sample can be collected by drilling the tube at right angles from the inside without being affected by the reaction force.

  In the sample core collecting method of the present invention, the inner wall of a reinforced concrete pipe is scanned with a metal detector to detect the position of the vertical and horizontal bars, and the pipe is connected by a core bit attached to a core drill at a position between the vertical and horizontal bars. A sample core of the tube is collected by drilling at a right angle. According to this, a sample core of a reinforced concrete pipe such as a PC pipe or a fume pipe can be collected at right angles from the inside of the pipe while avoiding vertical and horizontal bars.

In particular, in the case of a reinforced concrete pipe such as a PC pipe, the inner wall of the reinforced concrete pipe is scanned with a metal detector to detect the position of the longitudinal bars, and the pipe is formed by a first core bit attached to the core drill at a position between the longitudinal bars. A first hole reaching the vicinity of the transverse stripe across a plurality of transverse stripes is formed by drilling the inner surface of the tube in the caliber direction, and the bottom of the hole is scanned with a metal detector to determine the position of the transverse stripe. Detect and sample a sample core of the tube by drilling a second hole reaching the outer surface of the tube perpendicularly to the tube by a second core bit attached to the core drill at a position between the transverse bars in the hole To do.

According to this, the sample core on the outer surface side can be collected at right angles from the inside of the pipe while avoiding the vertical and horizontal bars of the reinforced concrete pipe. In this case, if the first hole is a long hole made of a plurality of holes cut so as to overlap in the longitudinal direction of the tube, the first hole can be extended to a plurality of horizontal stripes without making a large-diameter hole. It is possible to suppress the strength reduction at the sample core collection location. In addition, after the sample core is collected, the second hole can be closed with a rubber stopper, and the first hole can be closed with a cement material for repair, thereby preventing deterioration of the sample core collection point. .

  According to the pipe deterioration core sampler of the present invention, for example, a core core can be easily positioned in a reinforced concrete pipe such as a PC pipe or a fume pipe so as to be positioned on the inner diameter line of the pipe, and a sample core can be taken at a right angle from the pipe. it can.

  Further, according to the sample core collecting method of the present invention, the sample core can be collected at a right angle from the pipe while avoiding the reinforcing bars of the reinforced concrete pipe.

  Hereinafter, an embodiment of the present invention will be described. FIG. 4 is a perspective view showing an embodiment of a pipe deterioration core sampler used in the sample core collecting method of the present invention. In the sampling method of the present invention, a core sample is sampled from the inside of a reinforced concrete pipe such as the PC pipe 1 shown in FIG. 17 by using the core sampler 30 of FIG. 4 and the rebar detector 10 of FIG. Is.

  First, the structure of the PC tube will be described with reference to the perspective view of FIG. The PC pipe 1 is a PC steel wire in the circumferential direction on the outside of a concrete core (core concrete pipe) 2 that has been pre-stressed by, for example, a roll rolling method, in which prestress is introduced by the tension of the longitudinal PC steel wire, that is, the longitudinal bars 7. A steel wire, that is, a horizontal stripe 3 is wound, and a cover coat mortar 5 for covering the horizontal stripe 3 is further sprayed thereon.

  Since this PC pipe 1 is installed on a foundation where foundation work has been carried out and buried in the ground, the groundwater and air infiltrate and the deterioration of the cover coat mortar 5 occurs on the surface side of the PC pipe 1 That is, there is a high possibility that it is the upper side of the cylindrical cross section. Therefore, it is desirable to collect the sample core from the PC tube 1 on the surface side of the PC tube 1.

  In the present embodiment, a PC tube having an inner diameter of φ1500 (unit: “mm”; hereinafter the same) is taken as an example, and a case where a sample core is collected by the tube deterioration core sampler 30 will be described. The standard size of the PC pipe is defined in “JIS A5333-1979”, and the core concrete thickness of the φ1500 class II PC pipe is 85 mm, and the cover coat mortar thickness is 20 mm or 25 mm.

  As shown in FIG. 4, the pipe deterioration core sampler 30 of the present embodiment includes a drill holder 35 including a base 42 and a guide plate 40 that is movably provided with respect to the base 42. A core drill 32 is attached. In the present embodiment, two holes are formed in the longitudinal direction by the core bit (cutting teeth) 34 of the core drill 32 between two longitudinal bars (PC steel wires in the longitudinal direction) 7 adjacent to the PC pipe 1 in the circumferential direction. A long hole for detection (first hole) of the transverse bar (circumferential PC steel wire) 3 is formed, and then the core bit 34 is replaced with a small-diameter hole to replace the longitudinal length in the long hole. A hole (second hole) reaching the outer surface of the PC tube 1 is drilled between two transverse bars 3 adjacent to each other in the direction, and a cylindrical sample core is collected from the cover mortar 5 with the drilled hole. .

  The base 42 is formed of a cross-shaped flat plate whose outer side protrudes in a substantially rectangular shape in four directions, and shafts 36 are screwed at positions opposed to each other across the central axis of the base 42, and bearings are attached to the two shafts 36. A core plate 32 fitted to the guide plate 40 is supported by the guide plate 40 through the center plate 38 so as to be movable on the central axis above the base 42.

  The core drill 32 is detachably attached to a drill body 32A that is detachably attached to a mounting hole 39 (see FIG. 5) provided in the center of the guide plate 40 by a fixing means (not shown), and a drive shaft of the drill body 32A. The core bit 34 protrudes below the guide plate 40. The core drill 32 is moved down on the central axis of the base 42 via the guide plate 40 by being pushed by hand, and used for drilling the PC pipe 1.

  Pointed protrusions 43, 44, 45, 46 are screwed to the tips of the four rectangular portions of the base 42. The four protrusions 43 to 46 are arranged at the apex position of a square whose center is located on the central axis of the base 42, and protrude downward from the base 42 with the same protrusion amount in parallel with the central axis. When the base 42 is held by hand and pressed against the inner wall 8 of the PC tube 1 to bring all four projections 43 to 46 into contact with the inner wall of the PC tube 1, two adjacent projections 43 to 46 are adjacent to each other. For example, 43 and 44, 45 and 46 are both positioned on the inner wall 8 of the PC tube 1 in the longitudinal direction of the PC tube 1, and the central axis of the base 42 is positioned on the inner diameter line of the PC tube 1. Therefore, the core drill 32 to be attached to the guide plate 40 is positioned so as to be positioned on the inner diameter line of the PC tube 1, whereby the sample core can be taken by drilling the PC tube 1 at a right angle from the inside.

  Note that the four protrusions of the base 42 need only be positioned at the apex of a parallelogram of a concept that generally includes a square and a rectangle, and the central axis of the base 42 is placed on the inner diameter line of the PC tube 1 by the same pressing. Can be positioned.

  On the central axis of the base 42, a square shallow concave step 31 is provided inside a pair of shafts 36, and a through hole 41 through which the core bit 34 passes is provided at the center of the step 31. As shown in FIG. 5, a cross plate 33 with a cross hair is attached to the step 31 of the base 42, and the cross plate 33 is pressed on both sides by a pair of clips 37 provided on the base 42. 31 so that it does not come off from inside. The center of the cross plate 33 (cross position of the cross line) is located on the central axis of the base 42, and the cross plate 33 is looked through the drill mounting hole 39 without mounting the core drill 32 on the guide plate 40. The projections 43 to 46 of the base 42 are brought into contact with the inner wall of the PC tube 1 while aligning the center of 33 with the mark of the coring position on the inner wall of the PC tube 1. Thereby, the core drill 32 attached to the guide plate 40 is positioned so as to be positioned on the inner diameter line passing through the coring position of the inner wall 8 of the PC tube 1. Note that the cross plate 33 may be provided on the base 42 so as to be slidable with respect to the through hole 41 without providing the step 31 on the base 42.

A scale 48 is provided on the surface of the shaft 38 of the base 42, and a movable stopper 50 that can be fixed at a desired scale position is slidably fitted. The movable stopper 50 is for stopping the movement of the guide plate 40 by abutting it, and for defining the approach distance (drilling depth) of the core bit 34 to the tube wall of the PC tube 1. A stopper 47 for preventing the guide plate 40 from coming off is provided at the upper end of the shaft 36. A limit switch (not shown) is further provided at the upper end of the movable stopper 50 and is turned on when the guide plate 40 reaches the position of the limit switch, so that the core drill 32 is turned off and the rotation of the drill 32 is stopped. It may come to be.

  An injection tube 54 for injecting water from a water tank (not shown) is attached to the main body 32A of the core drill 32, and an opening / closing valve 52 supported by the guide plate 40 with a bracket 56 is inserted in the middle of the injection tube 54. Has been. The water injected from the tube 54 into the main body 32A passes through the water passages in the main body 32A and the shaft of the core bit 34, and is ejected from the tip of the core bit 34 for cooling and dust prevention during drilling.

  As described above, the sample core of the PC tube 1 is desirably collected from the surface side of the PC tube 1, and the PC tube 1 is held by holding the base 42 of the core sampler 30 as shown in FIG. For example, the core drill 32 is pressed and held at a position 45 ° obliquely above the PC tube 1 at a position 45 ° obliquely above the inner wall 8. Collect the core. The penetration depth d of the core bit 34 with respect to the PC tube 1 is set by fixing the movable stopper 50 at a position d on the scale 48 of the shaft 8. The sample core extraction depth (length of the sample core) of the cover mortar 5 is, for example, 70 mm. Therefore, when the sample core is taken from the cover mortar 5, the movable stopper is positioned at d = 70 mm on the scale 48 of the shaft 8. 50 is fixed.

  In order to collect the sample core from the inner wall of the PC tube 1, first, a first hole reaching from the inner wall 8 of the PC tube 1 to the vicinity of the lateral muscles between the longitudinal bars of the PC tube 1 is drilled. For this purpose, first, the position of the longitudinal bars (PC steel wires in the longitudinal direction) 7 of the PC pipe 1 is detected by the reinforcing bar detector shown in FIG. This rebar detector 10 is a portable metal detector of, for example, an induced current method, and when the surface of the inner wall 8 of the concrete pipe 1 is traced in the circumferential direction while pressing the measurement button 12 provided on the detector 10, Eddy currents are generated in the vertical bars 7 due to the high frequency transmitted from the detection hole 16, and the impedance between the inner wall 8 of the concrete pipe 1 is changed, and the presence of the vertical bars 7 is detected by detecting the impedance change. The The presence of the vertical stripe 7 is displayed as a change in the intensity of impedance on the display 14 and is notified by sounding an audio alarm. Therefore, the position of the detection hole 16 when the sound alarm sounds is the position of the vertical stripe 7. As for the position of the vertical stripe 7, two adjacent lines are detected in the circumferential direction.

  The detection depth of the rebar detector 10 depends on the diameter of the longitudinal bars 7, but in the present embodiment, the PC tube having a core concrete thickness of 50 to 100 mm is targeted for sampling, so the maximum detection depth is 100 mm. It only has to be about. In FIG. 1, reference numeral 11 denotes switches such as an on / off switch, a voice alarm switch, and a metal / wood selection switch.

  When two positions of the vertical stripes 7 of the PC tube 1 are detected, two drilling positions are determined in order to drill the first hole using the positioning tool 20 shown in FIG. This positioning tool 20 has a square bar member 22 slidably attached to one longitudinal bar portion of an L-shaped angle member 24 made of a square bar at its center, and projections 21 are formed on the lower surfaces of both ends of the square bar member 22. Protrusions 23 are respectively provided on the lower surfaces of the corners of the other horizontal bar portion 24, and a scale 26 is provided on the side surface of the horizontal bar portion.

  This positioning tool 20 is used as shown in FIG. For example, one coring position is marked with a choke, for example, at the center position between two adjacent vertical bars 7 detected by the reinforcing bar detector 10, and then the side of the angle member 24 of the positioning tool 20 at the marked position. The projection 23 is applied in such a posture that the longitudinal direction of the member is the longitudinal direction of the PC tube 1, and the projection 21 of the square bar member 22 is pressed against the inner wall of the PC tube 1 to hold the tool 20 immovably on the inner wall of the PC tube 1. In this state, the length is measured with the scale 26 of the horizontal bar portion of the tool 20, and the second coring position is marked with chalk, or a straight line is drawn to the second coring position.

  The two coring positions are for forming a long hole (a bowl-shaped hole) in which two holes are overlapped in the longitudinal direction on the pipe wall of the PC pipe 1 by drilling a hole at this position. The hole is formed in order to make the precision metal detector as close as possible to the horizontal stripe 3 on the inner side of the inner wall of the PC tube 1 so that the position of the horizontal stripe 3 can be easily detected, and two adjacent horizontal stripes. This is to ensure a sufficient length in the longitudinal direction of the PC tube 1 to detect 3. The long hole formed in the inner wall of the PC tube 1 uses the precision metal detector shown in FIG. 7 to detect the position of the horizontal stripe 3 after the bottom portion is flattened by covering the remaining uncut concrete.

  As shown in FIG. 7, the precision metal detector 60 has a shaft 66 attached between both sides of a U-shaped body frame 62, and an amplifier-separated proximity sensor 70 on a slide portion 64 slidably attached to the shaft 66. The projection 68 is provided on the lower surface of each end portion on both sides, and the scale 61 is provided on the upper surface of the central portion of the main body frame 62.

  The proximity sensor 70 is, for example, a high-frequency oscillation type metal detection sensor using electromagnetic induction. As shown in FIG. 8, the proximity sensor 70 includes a detection unit 72 that houses a detection coil in a metal cylinder portion whose outer surface is threaded. A nut 76 attached to a screw on the outer surface of the portion 72 is attached with the bottom plate of the slide portion 64 sandwiched from above and below. An output signal from the proximity sensor 70 is sent to an amplifier unit (not shown) through a coaxial cord 74, and the presence of the horizontal stripe 3 is detected by performing signal processing there.

  FIG. 9 shows a method for detecting the position of the horizontal stripe 3 by the precision metal detector 60. In FIG. 9, reference numeral 80 denotes a long hole (first hole) formed in the inner wall of the PC tube 1, and the bottom of the long hole 80 is flattened with uncut concrete. Hold the detector 60 by hand against the elongated hole 80 and press the four projections 68 of the main body frame 62 against the inner wall, so that the proximity sensor 70 moves in the elongated hole 80 over the entire longitudinal direction. The central portion of the main body frame 62 is held in alignment with the longitudinal direction of the PC tube 1. Then, the proximity sensor 70 is slid and scanned by hand through the slide part 64, and the position when the horizontal stripe 3 is detected by the signal processing in the amplifier unit is read on the scale 61 on the upper surface of the central part of the main body frame 62, The positions of the two horizontal stripes 3 adjacent in the longitudinal direction in the hole 80 are marked with chalk or the like.

  Next, a method for collecting the sample core of the present invention will be described. In the sampling method of the present invention, the position of the longitudinal bars 7 is detected from the inside of the PC pipe 1, the coring position avoiding the longitudinal bars 7 is determined, and the core concrete is removed by drilling from the inside of the PC pipe 1. The elongated hole 80 (first hole) is formed, the position of the transverse stripe 3 is detected in the elongated hole 80, the coring position avoiding the transverse stripe 3 is determined, the hole 80 is cut and covered. Take a core sample of mortar 5. Thereafter, the cover mortar hole (second hole) 82 (see FIG. 12) after the core sample is collected is closed with a rubber plug, and the core concrete hole 80 is closed with a polymer cement for repair. Hereinafter, each process will be described in detail.

  An outline of the sample core collection method is shown in the block diagram of FIG. FIG. 11 shows a cross-sectional view of the PC tube drilled, and FIG. 12 shows a view of the drilled portion of FIG.

  As shown in FIG. 10, first, the reinforcing bar detector 10 is moved in the circumferential direction on the surface of the inner wall 8 of the PC tube 1 to detect the positions of two longitudinal bars 7 adjacent in the circumferential direction in the core concrete 2. (Step S1). When the position of the vertical stripe 7 is detected by the intensity change of the display 14, the position of the vertical stripe 7 is marked using chalk or the like.

  Next, the central position in the circumferential direction between the two marks is set as the first coring position, and a straight line is drawn from the first coring position in the longitudinal direction of the PC tube 1 using the positioning tool 20, Set the distance position as the second coring position and mark it with chalk. Thereby, the coring position for drilling the long hole 80 with respect to the inner wall 8 of the PC tube 1 is determined (step S2). The two coring positions are oblong holes in which the drilled holes are overlapped in the longitudinal direction, and a length sufficient to detect the two horizontal stripes 3 in the oblong hole is ensured in the longitudinal direction of the PC tube 1. To.

  The method for determining the coring position for this long hole drilling will be further described as follows. First, mark the approximate position of the second coring with chalk. The marking position is removed from at least the tapered section of the outer surface of the PC tube 1 on the receiving port side.

  Next, the distance from the end joint position of the PC tube 1 at the two positions marked on the inner wall of the PC tube 1 is measured using a measuring tool such as a steel ruler, and the point that is the same distance as the position of each mark is measured. Two points are drawn in the circumferential direction on the inner wall of the PC tube 1 by determining a number of points in the circumferential direction using tools and connecting the points on the circumferential direction.

  Next, the reinforcing bar detector 10 is scanned along a circumferential line on the inner wall of the PC tube 1, and the position where the intensity change of the display 14 occurs is marked with chalk or the like. The number of points to be marked is two points per line in the circumferential direction. Of the marked points, two points located in the longitudinal direction of the PC tube 1 are applied with a steel ruler and a line is drawn with a chalk or the like, and this is performed for the other two points. The position of the vertical stripe 7 is displayed.

  Next, the circumferential distance between the two lines indicating the position of the two vertical bars 7 is measured at two points in the longitudinal direction using a steel ruler, and the center position in each circumferential direction is marked. Draw a central line connecting the two central points with a steel ruler.

  The first coring position is determined on this center line, and then the horizontal bar portion of the angle member 24 of the coring positioning tool 20 is applied to the center line, and the appropriate scale from the first coring position on the side scale 26. Determine the second coring position at a distance (approximately 18 mm).

  Next, a core bit having a diameter of 32 is attached to the core drill 32, and the core sampler 30 is positioned so that the core drill 32 is positioned on the inner diameter line through the base 42 with respect to the inner wall 8 of the PC tube 1 as shown in FIG. Positioning. Then, the core drill 32 is pushed by hand and drilled, and this is repeated at a position shifted in the longitudinal direction of the PC tube 1 to drill a similar φ32 hole to form a long hole 80 (core removal for a long hole). (Step S3). In the case of this embodiment, since the core concrete 2 has a thickness of 85 mm, the core bit 34 having a diameter of 32 is drilled to a depth of 75 mm.

  Next, a salabite is attached to the core drill 32 instead of the core bit, and the bottom of the removed long hole 80 is flattened (step S4). The distance in the longitudinal direction of the long hole 80 may be at least two pitches of the horizontal stripe 3.

  Next, the position of the horizontal stripe 3 is detected by scanning the inside of the long hole 80 with the precision metal detector 60 (step S5). Specifically, as described above, the main body frame 62 of the detector 60 is pressed and held close to the long hole 80 on the inner wall of the PC tube 1, and the long hole 80 is moved by moving the slide portion 64 by hand. Is scanned by the proximity sensor 70, and the position of the horizontal stripe 3 is detected and marked.

  Next, after determining the core removal position of the portion of the cover coat mortar 5, the core removal depth is set, and the core bit 34 is φ12.5 (those having a smaller diameter, for example, φ8.0 can be used. The sample core is difficult to be collected without being broken), and is positioned and core-bored in the same manner as before to collect the core sample of the cover mortar 5 (step S6). At this time, since the remaining thickness of the core concrete pipe 2 is 10 mm and the thickness of the cover coat mortar 5 is 20 mm or 25 mm, first, drilling holes from the core concrete to the cover mortar to confirm whether the cover mortar thickness is 20 mm. If this is not the case, drill a further hole to check the cover mortar thickness of 25 mm. The core extraction depth is set to be 30 mm or 35 mm from the position where the core bit 34 contacts the cover mortar 5.

  In FIG. 11, reference numeral 82 indicates a hole left after the core sample is collected. The collected sample is in the form of a cylinder with a 10 mm long concrete on the tip of a cover mortar with a length of 20 mm or 25 mm.

  In the above step S3, the core concrete of the PC tube 1 is corrugated to a depth of 75 mm (the surface indicated by C in FIG. 11) at a stretch. Then, after confirming the presence or absence of the vertical stripe 7 by the proximity sensor 70 at that position, the core is cut to the core cut surface A, for example, 20 mm before the horizontal stripe 3. Then, the bottom of the hole cut out on the core cut surface A is flattened, the position of the horizontal stripe 3 is detected by the proximity sensor 70, and the core is cut to the core cut surface B, for example, 15 mm in front of the horizontal stripe 3, where the bottom of the hole is flattened. You may make it advance the drilling of a hole to the core cut surface C of 10 mm before the horizontal stripe 3 so that the position of the horizontal stripe 3 may be detected.

  When the collection of the sample core of the cover mortar 5 from the PC tube 1 is completed as described above, the hole (hole of the mortar core) 82 opened in the cover mortar 5 is closed with a rubber plug to repair (step S7). Since the thickness of the cover mortar 5 can be determined as 20 mm or 25 mm by collecting the core sample, a rubber plug for 20 mm or 25 mm is prepared accordingly.

  FIG. 13 is a cross-sectional view showing a rubber plug attached to a hole in the cover mortar. The rubber plug 84 is sharpened so that it easily enters the hole 82 of the cover mortar, and an edge 85 serving as a stopper that prevents the entire hole 82 from entering the hole 82 protrudes from the base end, and has a cylindrical shape inside. It consists of a columnar body having a hole 86. The outer surface of the rubber plug 84 is provided with right-angled triangular protrusions 88 that are pointed in the insertion direction so that the downstream side in the insertion direction of the rubber plug 84 is perpendicular to the columnar portion, up to the base of the tip. The protrusion 88 is caught around the hole 82 on the inner surface of the hole 82 and the outer surface of the cover mortar 5 to hold the rubber plug 84 so that it cannot be easily removed from the hole 82. By blocking the hole 82 with the rubber plug 84 in this way, water is prevented from penetrating into the hole 82 from the soil in which the PC tube 1 is embedded.

  As shown in FIG. 14, the rubber plug 88 may have a triangular projection 89 whose downstream side in the insertion direction forms an acute angle with respect to the columnar portion. According to the rubber plug 88 having such a projection 89, it is more difficult to come out from the hole 82 of the cover mortar 5.

  In order to attach the rubber stopper 84 to the hole 82 of the cover mortar 5, a rubber stopper insertion metal fitting knocking hammer shown in FIG. 15 is used. The knocking hammer 90 is a block-shaped knocking hammer part 93 integrally provided with an elongated insertion fitting part 92. The outer diameter of the insertion fitting part 92 is slightly smaller than the cylindrical hole 86 of the rubber plug 84. It has a length sufficiently longer than the hole 86, and a concave portion 94 is formed on the end surface of the hammer portion 93.

  The insertion fitting 92 of the knocking hammer 90 is inserted into the hole 86 of the rubber plug 84, and the rubber plug 84 facing the hole 82 of the cover mortar 5 in this state is pushed by the knocking hammer 90 so that the rubber plug 84 is inserted into the hole 82. Install. The rubber plug 84 attached to the hole 82 of the cover mortar 5 is provided with an inner plug 98 as shown in FIG. 86.

  The inner plug 98 is made of plastic so that the diameter of the front end portion 97 is the same as the diameter of the cylindrical hole 86 of the rubber plug 84 so that it slightly expands from about 10 mm from the front end portion 97 toward the rear end portion 95. It is tapered. The inner plug insertion rod 96 is made of plastic, and includes a concave portion 99 having a diameter slightly larger than the diameter of the inner end 98 on the rear end portion 95 side and a length about half that of the inner plug 98. The rear end 95 side of the inner plug 98 is attached to the recess 99 of the insertion rod 96, and the inner plug 98 is pushed into the hole 86 of the rubber plug 84 from the distal end 97 side with the insertion rod 96. In the state of being pushed by the insertion rod 96, the entire inner plug 98 does not enter the hole 86 of the rubber plug 84, and the rear end 95 side protrudes from the edge 85 of the rubber plug 84. Then, the concave portion 94 of the knocking hammer 90 is applied to the portion protruding from the edge portion 85, the insertion fitting portion 92 at the other end is hit with a hammer, and the inner plug 98 is completely pushed into the hole 86 of the rubber plug 84. By inserting the inner plug 98 into the rubber plug 84, the rubber plug 84 is strongly pressed into the hole 82 of the cover mortar 5, and the degree of adhesion is further increased, making it more difficult to remove from the hole 82.

  Finally, polymer cement is applied and closed in the long hole 80 of the core concrete, and the repair of the long hole 80 is completed (step S8).

  The collected sample core (cover mortar core) is tested to check the progress of neutralization (step S9). In particular, when a sample core (core concrete) is collected from a fume tube, a strength test of the sample core is performed.

  As described above, in this embodiment, since a sample core is collected by drilling from the inside of the PC tube 1, it is not necessary to dig out the PC tube 1 and there is no need to obtain consent from the landowner. Sampling is possible at a location, and the accuracy of deterioration prediction is improved. In addition, since sample cores of core concrete can be obtained at the same time, it is possible to know the compressive strength of core concrete and other deterioration tests (such as sulfur penetration depth for sewers).

  By the way, although core collection is necessary for EPMA analysis such as a fume tube, it is desirable to set the core collection position in each of the transverse direction and longitudinal direction of the tube. Although the core collection position is set based on the distribution tendency of corrosion, it is generally known that the corrosion depth increases at the pipe top and the water surface boundary. Therefore, it is desirable that the core sampling position in the transverse direction of the pipe is collected near the top of the pipe or near the water surface boundary.

  In order to grasp the longitudinal distribution of the degradation position, the core sampling position in the longitudinal direction of the pipe is sampled at three or more cores at a certain interval, and the data of the corrosion depth and sulfur penetration depth vary. It would be desirable to be able to make correct / incorrect judgments.

  Furthermore, the setting of the core diameter needs to take into consideration the reinforcing bar diameter and the reinforcing bar interval, but it is necessary to set the core diameter so that the main bar is not cut particularly when the core is collected.

  When collecting the core of the inner surface of a pipe such as a fume pipe, it is possible to grasp the reinforcing bar diameter and reinforcing bar interval of existing pipes from the existing data, but the actual reinforcing bar position is unknown. To do. Next, the position of the core hole is determined and the core is removed. After collecting the core, repair the tube wall.

  The corrosion depth and sulfur penetration depth are measured by the core sampler thus collected. The corrosion depth is the thickness of the part where the concrete has deteriorated or peeled off. The length of the sampled core is measured with calipers or the like, and the corrosion depth is obtained by subtracting the length of the core from the tube thickness before deterioration.

  The sulfur penetration depth is measured by surface analysis of the core sampler with EPMA and color mapping.

  Another embodiment of the pipe deterioration core sampler of the present invention will be described. In the pipe deterioration core sampler 30 of the previous embodiment described with reference to FIG. 4 etc., the core drill 32 positioned by manually pressing the base 32 against the inner wall 8 of the PC pipe 1 The PC pipe 1 was drilled by moving the core drill 32 by hand while maintaining the positioning state by continuing the pressing. In the pipe deterioration core sampler of the present embodiment shown in FIG. 18, the mechanical drill can be used to position the core drill 106 by the base 102, hold the positioning state, and move the core drill 106 in the longitudinal direction of the PC pipe 1. I made it.

  FIG. 18 is a perspective view showing a pipe deterioration sampler of the present embodiment, and FIG. 19 is a half sectional view of the sampler.

  As shown in FIG. 18, the pipe deterioration core sampler 100 of the present embodiment includes a base 102, a column 103 provided on the center axis of the base 102, a lifting block 104 provided on the column 103, and the lifting block 104. The core drill 106 provided with the core bit 122 is attached to the bracket 105.

The base 102 is a base having a shape in which the arm is protruded in a cross shape from the center in four directions, and pointed projections 107a, 107b, 107c, 107d are screwed to the tip of the arm of the base 102, These four protrusions 107 (107a to 107d) protrude downward with the same protrusion amount in parallel with the central axis of the base 102. The tip of the arm of the base 102 is located at the apex of a square centered on the central axis of the base 102, so that all four protrusions 107 of the base 102 abut against the inner wall 8 of the PC tube 1. When pressed in this manner, the center axis of the base 102, and thus the axis of the column 103, is positioned on the inner diameter line of the PC tube 1.
The column 103 is composed of a main body 103a fixed to the central axis of the base 102 and a pad 109 provided at the upper end of the main body 103a so as to be able to advance and retreat in the axial direction. 109a is rotated to extend the pad 109, and a nut 109b screwed to the pad 109 is fastened to the pad 109, whereby the pad 109 is pressed against the inner wall 8 of the PC tube 1 on the opposite side of the base 102, and the PC tube 1 On the other hand, the core sampler 100 is held in the PC tube 1 with the central axis of the base 102 positioned on the inner diameter line of the PC tube 1. In order to apply the core sampler 100 to the PC pipe 1 having a large pipe diameter, the main body 103a of the support column 103 is separated vertically at the lower support plate 110b, and a spacer is added between them to make it longer. It can be done.

  An elevating block 104 constituting a screw rod elevating mechanism of the core drill 106 is attached to the main body 103a of the column 103, and two slide yokes 115 constituting a screw rod lateral movement mechanism of the core drill 106 are attached to the elevating block 104. Are penetrated horizontally at intervals. The bracket 105 is supported at the tip of the slide yoke 115 protruding forward from the main body 104 a of the lifting block 104. A base end of the slide yoke 115 is fixed to the support plate 116, and a drive screw 117 having a distal end rotatably supported by the elevating block 104 is screwed into the center portion of the support plate 116 and protrudes from the support plate 116. At the base end of the drive screw 117, the center of a disk 118a having a handle 118 on the outer periphery is fixed. Therefore, when the disk 118 a is rotated in one direction by the handle 118, the slide yoke 115 extends forward from the lifting block 104 via the support plate 116, and when it rotates in the reverse direction, it moves backward from the lifting block 104 to the bracket 105. The attached core drill 106 can be moved in the longitudinal direction of the PC tube 1.

  The slide yoke 115 is parallel to a line connecting two adjacent protrusions 107 of the base 102, for example, the protrusions 107a and 107b (or the same for the protrusions 107c and 107d), and the central axis of the PC tube 1 is on the inner diameter line. In the state where the base 102 is held so as to be positioned at the position, it extends in the longitudinal direction of the PC tube 1. Therefore, even if the core drill 6 is moved in the longitudinal direction of the PC tube 1 by the advancement / retraction of the slide yoke 115, the core drill 106 is always held in a state of being positioned on an inner diameter line parallel to the central axis of the base 102.

  Support plates 110a and 110b are fixed to the upper end position and the lower end position of the main body 103a of the column 103, respectively, and the screw rod 112 is rotatably supported between the support plates 110a and 110b. The elevating block 104 includes a main body part 104 a through which the slide yoke 115 passes and a small elevating part 104 b that supports the drive screw 117 of the slide yoke 115, and the main body part 104 a is slidable on the main body 103 a of the column 103. The main body 103 a of the support column 103 is provided by engaging the female screw 111 provided in the elevating part 104 b with the screw rod 112. A one-way lever 113 is attached to the lower end of the screw rod 112 protruding from the lower support plate 110b. When the screw rod 112 is rotated in one direction by the lever 113, the elevating block 104 rises along the main body 103a of the support column 103, and when the screw rod 112 is rotated in the reverse direction, it moves down along the main body 103a. 106 moves on the inner diameter line of the PC tube 1 parallel to the central axis of the base 102.

  The screw rod 112 is fitted with a stopper 128 for contacting the elevating part 104b of the elevating block 104, and the position of the stopper 128 is measured by a scale plate 129 in the height direction attached to the side surface of the elevating part 104b. By fixing to the screw rod 112, the depth of penetration of the core bit 122 of the core drill 106 into the PC pipe 1 can be set. The amount of movement of the core drill 106 in the longitudinal direction of the PC tube 1 can be measured by a scale plate 130 attached to the side surface of the elevating part 104 a of the elevating block 104.

  The core drill 106 includes a core drill main body 106a and the core bit 122 that is detachably attached to the upper end of the drive shaft 121 of the main body 106a. The core drill 106 is attached to and detached from the bracket 105 by inserting the lower part of the drill holder 120 to which the core drill body 106 a is fixed into a notch provided at the tip of the bracket 105 and screwing the drill holder 120 from the lower surface of the bracket 105. Can be attached freely. In place of the core drill 106, a precision metal detection sensor 132 can be similarly attached to the bracket 105 with screws, and the horizontal stripe 3 can be detected in the long hole 80 drilled in the PC tube 1.

  An extension guide ring stand 124 is attached to the drill holder 120 in parallel with the core bit 122. The tip of the core bit 122 is elastically supported by a spring 125 fitted to the outer surface of the guide ring stand 124. A guide ring holder 126 is fitted. A guide ring 127 provided with a packing 127a at the tip is attached to the holder 126, and the tip of the core bit 122 is covered, so that the tip of the core bit 122 passes from the water inlet 123a of the drill holder 120 through the water passage 123b inside the core bit 122. The cooling and dust-proof splattering sprayed out from the nozzle is prevented and discharged from the outlet 123c of the guide ring 127.

  In order to collect the sample core of the PC tube 1 with the tube deterioration core sampler 100 of the present embodiment, as shown in FIG. 20, first, the posture in which the support column 103 faces the position of, for example, 45 ° obliquely above the inner wall 8 of the PC tube 1 Then, the base 102 is pressed against the inner wall 8 so that the protrusions 107a to 107d are brought into contact with each other, the stopper 109 of the support column 103 is extended and pressed against the inner wall 8, and the core drill 106 is adjacent to the inner wall 8 of the PC pipe 1. It positions so that it may be located on the internal diameter line which passes along the 1st of the two coring positions marked between the muscles 7. FIG. If necessary, the core drill 106 is moved in the longitudinal direction between the PCs 1 by turning the handle 118 of FIG.

  Next, the core drill 106 is moved to the inner wall 8 of the PC pipe 1 by the lever 113 of FIG. 18, and the first coring position of the PC pipe 1 is drilled to the vicinity of the horizontal bar 3 by the core bit 122 of φ32. When the first drilling is completed, the lever 113 is used to pull out the core bit 122 from the hole 8 to the outside of the inner wall 8 of the PC tube 1 and the handle 118 extends the core drill 122 in the longitudinal direction of the PC tube 1 to the second core. Move to the ring position and drill the second coring position to the vicinity of the transverse bar 3 in the same manner. As a result, a long hole 80 (first hole) for detecting horizontal stripes in which two holes overlap in the longitudinal direction between the vertical bars 7 of the PC tube 1 is formed.

  Next, a salibit is mounted on the drive shaft 121 of the core drill 106, the bottom of the long hole 80 is flattened while moving in the longitudinal direction in the long hole 80, and then a precision metal detection sensor 132 is attached to the bracket 105, Within 80, the precision metal detection sensor 132 is moved in the longitudinal direction to detect the position of the horizontal stripe 3. Next, the core drill 106 was reattached to the bracket 105, and the coring position marked between the adjacent horizontal stripes 3 in the long hole 80 was drilled with the core bit 122 replaced with one having a diameter of 12.5. Collect 5 sample cores.

  Thereafter, in the same manner as in the previous embodiment, the second hole 82 formed by collecting the sample core is closed with a rubber plug 84, and the first hole 80 is closed with a polymer cement. Collection of the core and repair of the collection point are completed.

  According to the present embodiment, the projection 107 (107a to 107d) of the base 102 is brought into contact with the inner wall 8 of the PC tube 1 and the pad 109 of the column 103 is pressed against the inner wall 8, so that the core drill 106 is attached to the base 102. The core sampler 100 can be held in the PC tube 1 by being positioned on the inner diameter line of the PC tube 1 parallel to the central axis. And since the core drill 106 is moved on the inner diameter line with respect to the PC tube 1 via the screw rod lifting mechanism by the lever 113 and drilled, the PC tube 1 is drilled at a right angle from the inside without being influenced by the reaction force. A core sample can be taken. Further, since the core drill 106 can be moved in the longitudinal direction of the PC tube 1 by the handle 118 via the screw rod lateral movement mechanism, the longitudinal direction of the PC tube 1 can be set without resetting the core sampler 100 in the PC tube 1. A hole 80 for detecting a horizontal stripe can be formed by drilling two holes overlapping each other.

  In the above embodiments, taking the PC tube 1 as an example, the case where the sample core of the cover mortar is sampled at a right angle from the inside of the tube will be described. In the sampling process, the sample core is extracted from the concrete core 2 of the PC tube 1. It was also shown that it could be collected. The present invention can be similarly applied to a case where a sample core is collected from a concrete core of a fume tube.

  As described above, the pipe deteriorated core sampler according to the present invention is extremely useful as an apparatus for collecting a sample core of a reinforced concrete pipe such as a PC pipe or a fume pipe from the inside of the pipe.

It is a top view which shows the reinforcing bar detector used with the core sample collection method of this invention. It is a perspective view which shows the coring positioning tool used with the core sample collection method of this invention. It is a top view which shows the usage method of the coring positioning tool of FIG. It is a perspective view which shows one Embodiment of the core sampler of this invention. It is a perspective view which shows the place which mounted | wore the cross sample to the core sampler of FIG. 4, and removed the core drill. It is a schematic side view which shows the attitude | position at the time of drilling of the core sampler of FIG. It is a perspective view which shows the precision metal detector used with the core sample collection method of this invention. It is a front view which shows the proximity sensor installed in the detector of FIG. It is a figure which shows the usage condition of the metal detection sensor slide apparatus which concerns on this embodiment. It is a block diagram which shows the sample core collection method of this invention. It is sectional drawing which shows PC pipe drilled according to the extraction | collection method of this invention. It is the figure which looked at the hole part of FIG. 11 from the inner side of PC pipe. It is sectional drawing which shows the place which attached the rubber stopper to the 2nd hole of the drilling part of the PC pipe | tube of FIG. FIG. 14 is a partial view showing another example of the protrusion of the rubber plug of FIG. 13. FIG. 12 is a cross-sectional view showing a rubber plug insertion metal fitting / knocking hammer used for attaching the rubber plug of FIG. 11 to the second hole of the drilled portion of the PC pipe. It is sectional drawing which shows the inner stopper inserted in the hole of the rubber stopper of FIG. 13, and the inner stopper insertion rod used for the insertion. It is a partially broken perspective view which shows the structure of PC pipe | tube. It is a perspective view which shows other embodiment of the core sampler of this invention. It is a longitudinal cross-sectional view of the core sampler of FIG. It is a figure which shows the place which installed the core sampler of FIG. 18 in the pipe crossing direction inside PC pipe | tube.

Explanation of symbols

1 PC pipe 2 Concrete core 3 Transverse bar (circumferential PC steel wire)
5 Cover coat mortar 7 Longitudinal bars (longitudinal direction PC steel wire)
DESCRIPTION OF SYMBOLS 10 Reinforcement detector 20 Coring positioning tool 44-48 Protrusion 30 Pipe deterioration sampler 32 Core drill 33 Cross plate 34 Core bit 36 Shaft 39 Drill attachment hole 40 Guide plate 41 Hole through which core bit passes 42 Base 50 Movable stopper 60 Precision metal detector 70 Proximity sensor 80 1st hole 82 2nd hole 84 Rubber plug 90 Rubber plug insertion metal fitting combined knocking hammer 96 Middle plug insertion rod 98 Middle plug 100 Pipe deterioration core sampler 102 Base 103 Post 104 Lifting block 105 Bracket 106 Core drill 107a ~ 107d Protrusion 109 Pad 112 Screw rod 113 One-way lever 115 Slide yoke 118 Handle 118a Screw rod 120 Drill holder 121 Drive shaft 122 Core bit 132 Precision metal detection sensor

Claims (8)

  A core drill that drills a reinforced concrete pipe from the inside at a position between the vertical and horizontal bars, and protrudes at the position corresponding to the apex of the parallelogram with the same protrusion amount parallel to the central axis perpendicular to the center of gravity of the parallelogram. The core drill is positioned on the central axis by positioning the core drill so as to be positioned on the diameter of the tube by bringing the four projections into contact with the inner wall of the tube. A pipe deterioration core sampler comprising a base movably attached along the pipe.   A through-hole through which a core bit of the core drill passes is formed on the central axis of the base, and a support base for supporting the core drill is provided above the base so as to be movable on the central axis. The pipe deterioration core sampler according to claim 1.   The core drill is disposed offset from the central axis of the base, and the main body of the column is fixed on the central axis of the base, and is pressed against the inner wall of the reinforced concrete pipe opposite to the base. The pipe deterioration core sampler according to claim 1, further comprising a support column in which a pad to be mounted is disposed so as to be movable back and forth in an axial direction with respect to a main body of the support column.   An elevating block is provided to be movable in the axial direction of the support column with respect to the main body of the support column, and a bracket is provided to be movable on a longitudinal line of the reinforced concrete pipe passing through the central axis with respect to the elevating block. The pipe deterioration core sampler according to claim 3, wherein the core drill is detachably attached.   The pipe deterioration core sampler according to claim 4, further comprising a metal sensor for detecting a reinforcing bar of the reinforced concrete pipe, wherein the metal sensor and the core drill are selectively attached to the bracket. The inner wall of the reinforced concrete pipe is scanned with a metal detector to detect the position of the longitudinal bars, and the inner surface of the pipe is cut in the caliber direction of the pipe by the first core bit attached to the core drill at a position between the longitudinal bars. Forming a first hole that reaches the vicinity of the transverse line across a plurality of transverse lines, scans the bottom of the hole with a metal detector to detect the position of the transverse line, and between the transverse lines in the hole; A sample core collecting method comprising: sampling a sample core of the pipe by drilling a second hole reaching the outer surface of the pipe by a second core bit attached to the core drill at a position perpendicular to the pipe.   The sample core collecting method according to claim 6, wherein the first hole is a long hole formed of a plurality of holes cut so as to overlap with a longitudinal direction of the tube.   8. The sample core collecting method according to claim 6, wherein after the sample core is collected, the second hole is closed with a rubber plug, and the first hole is closed with a cement material to repair the sample core.

Images