JP2016017273A - Structure and method for reinforcing existing coastal structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure and a method for reinforcing an existing coastal structure, which are excellent in workability and which can increase flexural strength of an existing wall.SOLUTION: A structure for reinforcing an existing coastal structure includes: a ground improvement part 10 that improves ground 1a behind an existing wall 4; an anchor insertion hole 11 that is opened in a ground surface of the ground improvement part 10 and that reaches stable ground 3 at a desired depth; and an anchor material 12 that is inserted along the anchor insertion hole 11, the one end of which is anchored to the stable ground 3, and the other end of which is anchored to the ground improvement part 10. The ground improvement part 10 is supported by the stable ground 3 via the anchor material 12.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reinforcing structure and a reinforcing method for an existing bank structure such as a seawall or a quay using an anchor material such as a ground anchor.

  In harbor facilities, reinforcement of existing shore structures such as revetments or quay walls may be necessary to increase the depth of water and increase seismic reinforcement associated with the enlargement of ships.

  Conventionally, as a method of reinforcing existing shore structures, the ground improvement method for reducing the earth pressure acting on the existing wall by improving the ground behind the existing wall made of sheet piles and steel pipe sheet piles, or on the front or back side of the existing wall A new sheet pile and steel pipe sheet pile, and a new construction behind the sheet pile, and a new pile construction and a new sheet pile connected to each other with a tie rod, a sheet pile structure construction method or ground improvement construction method A construction method that uses both a sheet pile structure construction method and the like is known.

  As another method for reinforcing the existing shore structure, as shown in FIG. 10, a temporary base 101 (or a work table ship) is installed on the sea side of the existing wall 100 made of sheet piles, and the temporary base 101 is cut. A drilling machine 102 is installed and an anchor insertion hole reaching the stable ground 103 obliquely from the sea side is drilled. An anchor material 104 such as a ground anchor is inserted into the anchor insertion hole, and one end of the anchor material 104 is connected to the stable ground. There is also known a construction method in which the other wall is fixed to the existing wall (or a sheet pile constituting the same) 100 and the existing wall 100 is supported on the stable ground 103 via the anchor material 104 (for example, patent) Reference 1).

JP-A-1-198920

  However, the conventional ground improvement method has a problem that the ground improvement range is wide in order to ensure the stability of the ground improvement part, and the economic burden is large.

  In addition, in the conventional sheet pile structure construction method, it is a structure in which a new construction is installed and the upper construction of the new construction and the new sheet pile is connected with tie rods, so the surface part must be dug up During construction, there was a problem that existing quay structures such as quay walls could not be operated, and there was a problem that it was difficult to install a construction work if there were ground facilities.

  Further, since the tie rod is fixed to the superstructure of the existing wall, the effect of improving the bending strength of the existing wall cannot be expected.

  On the other hand, in the conventional reinforcement method using anchor material, the installation efficiency of the anchor insertion hole and anchor material must be set up on the surface of the water and the work table ship must be removed after construction. Unfortunately, there was a problem that the construction cost increased, and in the state where a temporary mount and work table ship were installed on the water surface, the berthing of the ship was restricted and the operation of the quay was also restricted.

  In addition, the anchoring position of the anchor material on the sea side must be set on the sea due to construction problems, which contributes to the strengthening of the strength of the existing construction work, but the fulcrum position when calculating the stress of the existing wall made of sheet piles Since it becomes a high position, there also existed a problem that it was difficult to contribute to the strengthening of the proof stress of the existing wall.

  Therefore, in view of such conventional problems, the present invention has been made for the purpose of providing a reinforcing structure and a reinforcing method for an existing shore structure that is excellent in workability and can improve the bending strength of an existing wall. is there.

  The feature of the invention according to claim 1 for solving the conventional problems as described above is that the ground behind the existing wall is improved in the reinforcing structure of the existing shore structure in which the existing wall is installed on the front side. The ground improvement portion, one end opened to the ground surface of the ground improvement portion, the other end is inserted along the anchor insertion hole, the anchor insertion hole is inserted along the anchor insertion hole, and one end is fixed to the stable ground. An anchor member fixed to the ground improvement portion, and the ground improvement portion is supported by the stable ground via the anchor material. .

  According to a second aspect of the present invention, in addition to the structure of the first aspect, the anchor insertion hole is a slant hole extending at a desired depth from the ground improvement portion at a desired angle and extending to a stable ground. To have a part.

  According to a third aspect of the present invention, in addition to the structure of the second aspect, the anchor insertion hole includes a vertical hole portion drilled to a desired depth from the ground surface of the ground improvement portion, and the vertical hole portion. A bent hole portion bent toward the rear, and an inclined hole portion that is inclined at a desired angle continuously with the bent hole portion and extends from the ground improvement portion at a desired depth to reach the stable ground. It is in.

  The feature of the invention described in claim 4 is that, in addition to the configuration of claim 2 or 3, a plurality of anchor insertion holes having different depths at the rear end face of the ground improvement portion of the inclined hole portion are arranged in parallel. is there.

  According to a fifth aspect of the present invention, in addition to the structure of any one of the first to fourth aspects, a fixing body is provided in which one end of the anchor material is fixed to the ground surface portion of the ground improvement portion. is there.

  According to a sixth aspect of the present invention, in the method for reinforcing an existing shore structure in which an existing wall is installed on the front side, a ground improvement portion is formed by improving the ground behind the existing wall, A hole drilling machine is installed on the ground surface, the hole drilling machine opens the ground surface of the ground improvement part, and drills an anchor insertion hole leading to the stable ground, and allows the anchor material to pass through the anchor insertion hole. The anchor material is fixed to the stable ground, the other end is fixed to the ground improvement portion, and the ground improvement portion is supported by the anchor material on the stable ground. .

  According to a seventh aspect of the present invention, in addition to the configuration of the sixth aspect, a drilling machine capable of straight excavation and bending excavation with a desired curvature radius is used, and a desired depth is obtained from the ground surface of the ground improvement portion. After the vertical hole portion is drilled in the vertical direction, a bent hole portion bent backward from the vertical hole portion is drilled, and after the ground improvement portion at a desired depth continuously with the bent hole portion. The anchor insertion hole extending from the ground surface portion of the ground improvement portion to the stable ground is formed by drilling a slant hole portion that passes through the end surface and is inclined at a desired angle from the rear end surface of the ground improvement portion. Then, the anchor material is inserted along the anchor insertion hole.

  As described above, the reinforcement structure for an existing shore structure according to the present invention is a ground improvement portion that improves the ground behind the existing wall in the reinforcement structure for an existing shore structure in which an existing wall is installed on the front side. , One end opened to the ground surface of the ground improvement part, the other end is inserted along the anchor insertion hole, and the other end is fixed to the stable ground, and the other end is fixed to the ground. With the anchor material fixed to the improved portion, and by allowing the ground improved portion to be supported by the stable ground via the anchor material, the ground improved range can be reduced and construction can be performed on the ground. It is excellent in workability and can reinforce existing shore structures such as revetments and quay walls. In addition, there is no need to dig up the ground surface, and there is no need to install an erection frame or work platform on the water. The occupation period can be shortened and efficient operation of the existing shore structure can be secured.

  In the present invention, the anchor insertion hole has a slanted hole portion extending from the ground improvement portion at a desired depth at a desired angle and extending to a stable ground, thereby reducing the working earth pressure. be able to.

  Further, in the present invention, the anchor insertion hole includes a vertical hole portion drilled to a desired depth from the ground surface of the ground improvement portion, a bent hole portion bent backward from the vertical hole portion, and the bent portion. The support point by the anchor material is located at a low position by providing an inclined hole portion that is inclined continuously at a desired angle with the hole portion and extends from the rear end surface of the ground improvement portion at a desired depth to reach the stable ground. The bending strength of the ground improvement part can be increased.

  Furthermore, in the present invention, by arranging in parallel a plurality of anchor insertion holes having different depths at the rear end surface of the ground improvement portion of the oblique hole portion, the fulcrum span in the depth direction can be further reduced, and the ground improvement The strength burden on the part can be reduced.

  Further, in the present invention, the fixing work can be easily performed by providing a fixing body to which one end of the anchor material is fixed on the ground surface portion of the ground improvement portion.

  Further, in the present invention, in the method for reinforcing an existing shore structure in which an existing wall is installed on the front side, a ground improvement portion is formed by improving the ground behind the existing wall, and a hole is drilled in the ground surface of the existing revetment. A drilling machine, drilling an anchor insertion hole reaching the ground surface of the ground improvement portion by the drilling machine and reaching the stable ground, inserting an anchor material into the anchor insertion hole, and By fixing one end to the stable ground, fixing the other end to the ground improvement portion, and supporting the ground improvement portion to the stable ground by the anchor material, the ground improvement range can be reduced and temporarily installed on the sea. The ground construction is possible without the need for a pedestal, etc., and it is not necessary to dig up the surface part, so the occupation range during construction can be reduced, and the occupation period of existing shore structures can be shortened due to construction. shore It is possible to ensure efficient operation of the existing coast structures etc., it is possible to improve the workability and economy.

  Further, in the present invention, using a drilling machine capable of straight excavation and bending excavation with a desired radius of curvature, after drilling the vertical hole portion in the vertical direction from the ground surface of the ground improvement portion to a desired depth, A bent hole portion bent toward the rear from the vertical hole portion is drilled, and passes through the rear end surface of the ground improvement portion at a desired depth continuously with the bent hole portion, and is desired from the rear end surface of the ground improvement portion. The anchor insertion hole extending from the ground surface portion of the ground improvement portion to the stable ground is formed by drilling a slant hole portion inclined at an angle of, and then the anchor material is disposed along the anchor insertion hole. By inserting the anchor member, the anchor member can be installed on the ground, and the support force acting position of the anchor member with respect to the ground improvement portion can be freely designed.

It is a longitudinal cross-sectional view which shows an example of the reinforcement structure of the existing bank structure concerning this invention. It is a top view same as the above. (A) (b) is a schematic diagram for demonstrating the action state of the earth pressure in the reinforcement structure of the existing shore structure same as the above. It is a longitudinal cross-sectional view which shows the structure of the existing revetment. It is a longitudinal cross-sectional view which shows the state of the ground improvement process in the reinforcement method of the existing bank structure concerning this invention. It is a longitudinal cross-sectional view which shows the state of an anchor penetration hole drilling process same as the above. It is a longitudinal cross-sectional view which shows another example of the reinforcement structure of the existing bank structure concerning this invention. It is a longitudinal cross-sectional view which shows another example of the reinforcement structure of the existing shore structure concerning this invention. It is a longitudinal cross-sectional view which shows another example of the reinforcement structure of the existing shore structure concerning this invention. It is a longitudinal cross-sectional view which shows the state of the anchor penetration hole drilling process in the reinforcement method of the conventional existing bank structure.

  Next, the embodiment of the reinforcement structure of the existing shore structure according to the present invention will be described based on the embodiment shown in FIGS. In the figure, reference numeral 1 denotes an existing shore structure such as a revetment or quay, reference numeral 2 denotes a water surface, and reference numeral 3 denotes a stable ground. In the present invention, the sea side of the shore is described as the front, and the direction intersecting the front-rear direction in the plane is described as the horizontal direction.

  An existing pier structure 1 such as a revetment or a quay is provided with an existing wall 4 made of sheet piles installed on the front surface, and an existing set-up work 5 made of piles buried behind the existing wall 4 at intervals. The upper work 4a of the wall 4 and the upper work of the existing paddle work 5 are connected by a support member 6 such as a tie rod.

  As shown in FIGS. 1 and 2, the reinforcing structure of the existing shore structure 1 has a ground improvement portion 10 obtained by improving the ground 1 a behind the existing wall 4, an opening in the ground surface of the ground improvement portion 10, and The anchor insertion hole 11 having a slant hole portion 11c that is inclined at a desired angle from the rear end surface 10a of the ground improvement portion 10 at a desired depth and reaches the stable ground 3 is inserted along the anchor insertion hole 11, and one end Is anchored to the stable ground 3 and the other end is anchored to the ground improvement portion 10, and the ground improvement portion 10 is supported on the stable ground 3 via the anchor material 12.

  The ground improvement part 10 is formed by improving the rear side ground of the existing wall 4 over a desired range by chemical solution injection or the like, and has a stable strength that can withstand anchor anchoring.

  The ground improvement range in the front-rear direction is smaller than the distance between the existing wall 4 and the existing preparatory work 5 and the ground improvement range of the existing revetment reinforcement method by the conventional ground improvement.

  The anchor insertion hole 11 includes a vertical hole portion 11a that is vertically drilled from the ground surface of the ground improvement portion 10 to a desired depth, a bent hole portion 11b that is bent backward from the vertical hole portion 11a, and a bent hole. An inclined hole portion 11c that is inclined at a desired angle from the portion 11b and reaches the stable ground 3 through the rear end surface 10a of the ground improvement portion 10 at a desired depth position.

  As shown in FIG. 2, the anchor insertion holes 11 are arranged in parallel, and adjacent anchor insertion holes 11 have different depths h1 and h2 in the rear end surface 10a of the ground improvement portion 10 of the oblique hole portion 11c. The points where the support force by the anchor material 12 is formed are different from each other in the depth direction.

  The anchor material 12 is composed of a PC steel material or the like, one end of which is fixed to the stable ground 3 by pressurizing and solidifying a solidified material such as a grout 13 at the tip of the anchor insertion hole 11, and the other end is ground. It is fixed in a tensioned state on the fixing body 14 installed on the surface of the improvement section 10.

  Reference numeral 16 in the figure denotes a packer for closing the anchor insertion hole 11, and the solidification material such as the grout 13 is pressurized to the packer 16 in a state where the end of the anchor insertion hole 11 is blocked by expanding the packer 16. Injected.

  The fixing body 14 is composed of a plate-like precast concrete block or the like, and is installed in the vicinity of the upper work 4 a of the existing wall 4 on the ground surface portion of the ground improvement portion 10.

  Reference numeral 15 in the drawing denotes fixing means for fixing the anchor material 12 to the fixing body 14. The fixing means 15 is not particularly limited. For example, a screw portion may be provided at the end portion of the anchor member 12, and a nut may be screwed into the screw portion to be tightened. A fixing unit may be used.

  The reinforcement structure of the existing shore structure thus configured includes the ground improvement portion 10 on the rear surface side of the existing wall 4, and the ground improvement portion 10 is supported on the stable ground 3 by the anchor material 12. 4 working earth pressure is reduced.

  Moreover, since the ground improvement part 10 itself is supported by the stable ground 3 by the anchor material 12, the high stability of the ground improvement part 10 is securable in the ground improvement range narrower than a conventional construction method.

  Furthermore, the ground improvement part 10 can be considered as a beam model, and the anchor insertion hole 11 is formed so that the extension line to the front of the oblique hole part 11c intersects the existing wall 4 at a desired height below the water surface. Accordingly, as shown in FIG. 3A, the position of the fulcrum 15a by the anchor material 12 can be lowered to a desired depth position, and the fulcrum span in the depth direction can be reduced.

  Furthermore, by arranging a plurality of anchor insertion holes 11 having different depths h1 and h2 in the ground improvement portion 10 rear end surface 10a of the oblique hole portion 11c in parallel, as shown in FIG. By supporting the ground improvement part 10 with the plurality of fulcrums 15b, 15b, the fulcrum span in the depth direction can be further reduced, and the strength burden on the ground improvement part 10 can be reduced.

  Next, the reinforcement method of the existing shore structure based on this invention is demonstrated based on FIG.1 and FIGS. In addition, the same code | symbol is attached | subjected and demonstrated to the structure similar to the above-mentioned Example. Moreover, FIG. 4 shows the state of the existing shore structures, such as a revetment and a quay before reinforcement, and the code | symbol 4 is an existing wall and 5 is an existing construction.

  In the method of the present invention, first, as shown in FIG. 5, the rear surface side ground 1 a of the existing wall 4 is improved over a desired range by chemical injection or the like, and the ground improvement portion 10 is formed.

  The ground improvement range may be smaller than the distance between the existing wall 4 and the existing preparatory work 5 and the ground improvement range of the existing revetment reinforcement method by the conventional ground improvement.

  Next, as shown in FIG. 6, a drilling machine 20 is installed on the ground of the existing shore structure 1 such as a seawall or a quay, and the drilling machine 20 opens the ground surface of the ground improvement unit 10, and the desired The anchor insertion hole 11 that is inclined at a desired angle from the rear end surface 10a of the ground improvement portion 10 to the stable ground 3 at a depth of is drilled.

  The drilling machine 20 is a drilling machine that is used for inclined drilling and bending drilling, and is capable of straight drilling and curved drilling with a desired radius of curvature. A casing 22 is embedded.

  The drilling machine 20 is provided with a bit position measuring means for measuring the position of the excavation bit 23 composed of various sensors. Based on information from the bit position measuring means, a propulsion distance, a bending radius at the time of bending drilling, etc. Can be controlled.

  In the drilling operation of the anchor insertion hole 11, first, the vertical hole portion 11 a reaching a desired depth is drilled by propelling straightly in the vertical direction from the ground surface side of the ground improvement portion 10.

  Next, when the vertical hole portion 11a reaches a desired depth, the drilling bit 23 is bent while bending the drilling direction rearward with a desired radius of curvature, and the bent portion is bent rearward continuously with the vertical hole portion 11a. The hole 11b is drilled.

  Then, when the bent hole portion 11b reaches a desired position, that is, a position where the drilling direction of the excavation bit 23 coincides with the inclination direction of the oblique hole portion 11c, the drilling hole 11b is drilled straight from the position in an oblique direction. To the rear end surface 10a of the ground improvement portion 10 at a desired depth, and further, the inclined hole portion 11c which is inclined at a desired angle from the rear end surface 10a of the ground improvement portion 10 and reaches the stable ground 3 is drilled. .

  As a result, the anchor is inserted into the ground improvement portion 10 having an inclined hole portion 11c that opens to the ground surface and is inclined at a desired angle from the rear end surface 10a of the ground improvement portion 10 to the stable ground 3 at a desired angle. A hole 11 is formed.

  When the anchor insertion hole 11 is formed, as shown in FIG. 1, the anchor material 12 is inserted into the anchor insertion hole 11, and it is confirmed that the tip of the anchor material 12 reaches the stable ground 3, and the grout is injected. While pulling out the casing 22, a solidified material such as grout is pressurized and injected into the tip of the anchor insertion hole 11, and the grout at the tip is solidified to fix one end of the anchor material 12 to the stable ground 3.

  On the other hand, after the anchor insertion hole 11 is formed, the fixing member 14 to which the upper end of the anchor material 12 is fixed is disposed on the ground surface portion of the ground improvement portion 10.

  Then, one end of the anchor material 12 is tensioned in a state of being fixed to the stable ground 3, and the other end is fixed to the fixing body 14 by a fixing means 15 such as a nut tightening in that state, and the ground improvement portion 10 is It is supported on the stable ground 3.

  Then, a series of operations from the formation of the anchor insertion hole 11, the insertion of the anchor material 12 and the anchoring of the anchor material 12 is repeated while moving the hole drilling machine 20 in the lateral direction (vertical direction in FIG. 2). The insertion holes 11 are arranged in parallel.

  A plurality of anchor insertion holes 11 having different depths in the rear end surface 10a of the ground improvement portion 10 of the oblique hole portion 11c are arranged in parallel by changing the arrival depth of the vertical hole portion 11a between the anchor insertion holes 11 adjacent to each other. To do.

  The existing shore structure reinforcement method constructed in this way does not require the installation of temporary mounts or work table boats, and does not require significant excavation of the ground surface, so the occupation area during construction is small and berthing during construction is possible. Therefore, the occupation period accompanying the construction of existing shore structures such as revetments or quay walls can be greatly shortened, and efficient operation of the existing structures can be ensured.

  Further, in the reinforcing structure of the existing shore structure according to the present invention, the fixing member 14 is not used, and the grout 30 is injected under pressure into the bent hole portion 11b of the anchor insertion hole 11, as shown in FIG. The anchor material 12 may be fixed in the ground improvement portion 10. In the present embodiment, the same components as those in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  The anchor material 12 is fixed to the ground improvement portion 10 in a state where the sealing members such as the packers 31 and 31 are contracted at predetermined positions of the anchor material 12, and the anchor material 12 is inserted into the anchor insertion hole 11. After fixing the tip to the stable ground 3, grout or the like is injected into both packers 31, 31 to expand them, and both ends of the bent hole portion 11 b are closed, and then between the packers 31, 31 through an injection pipe (not shown). Is performed by injecting grout under pressure.

  In this way, the grout 30 is pressure-injected into the bent hole portion 11b, and the anchor material 12 is fixed to the ground improvement portion 10, whereby the anchor material 12 can be reliably fixed to the ground improvement portion 10, and the anchor in the bent hole portion 11b is fixed. The influence which the tension | tensile_strength which acts on the material 12 has on the ground improvement part 10 can be excluded, and disorder of the ground improvement part 10 can be prevented.

  Further, in the above-described embodiment, the case where the fixing body 14 is provided and the case where the fixing body 14 is provided separately from the existing wall 4 has been described. However, the fixing body 14 is integrated with the upper work 4a of the existing wall 4 so You may make it act also on the existing wall 4. FIG.

  The anchor insertion hole 11 only needs to be open to the ground surface of the ground improvement portion 10 and reach the stable ground 3. For example, as shown in FIG. Further, it may have a shape extending obliquely rearward from the rear end surface 10a of the ground improvement portion 10 at a desired depth, and as shown in FIG. 9, the anchor insertion hole 11 is formed in the vertical direction. Also good. In addition, the same code | symbol is attached | subjected to the structure similar to the above-mentioned Example, and description is abbreviate | omitted.

DESCRIPTION OF SYMBOLS 1 Existing revetment 1a Ground 2 Water surface 3 Stable ground 4 Existing wall 5 Existing preparatory work 10 Ground improvement part 10a Rear end surface 11 Anchor insertion hole 11a Vertical hole part 11b Bending hole part 11c Oblique hole part 12 Anchor material 13 Grout 14 Fixing body 16 Packer 15 Fixing means 20 Drilling machine 22 Casing 23 Drilling bit 30 Grout 31 Packer

Claims (7)

In the reinforcement structure of the existing shore structure where the existing wall is installed on the front side,
The ground improvement part which improved the ground behind the existing wall, one end opened to the ground surface of the ground improvement part, the other end is inserted along the anchor insertion hole, the anchor insertion hole reaching the stable ground, An anchor material fixed at one end to the stable ground and the other end fixed at the ground improvement portion, and the ground improvement portion is supported by the stable ground via the anchor material. Reinforcing structure for existing shore structures.   The reinforcing structure for an existing shore structure according to claim 1, wherein the anchor insertion hole has a slant hole portion extending at a desired depth from the ground improvement portion at a desired angle and extending to a stable ground.   The anchor insertion hole includes a vertical hole portion drilled to a desired depth from the ground surface of the ground improvement portion, a bent hole portion bent backward from the vertical hole portion, and the bent hole portion. The reinforcement structure of the existing shore structure of Claim 2 provided with the slant hole part which inclines at a desired angle and extends from a ground improvement part by the desired depth and reaches the said stable ground.   The reinforcement structure of the existing shore structure of Claim 2 or 3 which has arrange | positioned the several anchor penetration hole from which the depth in the rear-end surface of the said ground improvement part of the said oblique hole part differs in parallel.   The reinforcement structure of the existing shore structure of any one of Claims 1-4 provided with the fixing body by which the end of the said anchor material is fixed to the ground surface part of the said ground improvement part. In the reinforcement method of the existing shore structure where the existing wall is installed on the front side,
Improving the ground behind the existing wall to form a ground improvement part, installing a drilling machine on the ground surface of the existing revetment, opening to the ground surface of the ground improvement part by the drilling machine, and stabilizing The anchor insertion hole reaching the ground is drilled, the anchor material is inserted into the anchor insertion hole, one end of the anchor material is fixed to the stable ground, and the other end is fixed to the ground improvement portion, and the ground improvement is performed. A portion is supported on the stable ground by the anchor material, and a method for reinforcing an existing shore structure is provided. Using a drilling machine capable of straight excavation and bending excavation with a desired radius of curvature,
After the vertical hole portion is drilled in the vertical direction from the ground surface of the ground improvement portion to a desired depth, a bent hole portion bent backward from the vertical hole portion is drilled, and continuous with the bent hole portion. Pass through the rear end surface of the ground improvement portion at a desired depth and drill a slant hole portion inclined at a desired angle from the rear end surface of the ground improvement portion to reach the stable ground from the ground surface portion of the ground improvement portion. Forming the anchor insertion hole,
Then, the reinforcing method of the existing shore structure according to claim 6, wherein the anchor material is inserted along the anchor insertion hole.

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