Bottom cover for sealing through holes in floor slabs, and method for sealing through holes in floor slabs

Abstract

To provide a bottom cover for closing a through hole of a floor slab, which can close the lower opening of a through hole formed in a floor slab of an existing structure with a lower surface of the floor slab, when the through hole is closed even if a space below the floor slab is a narrow space where no one can enter, and to provide a method for closing the through hole of the floor slab.SOLUTION: A bottom cover 20 that closes a through hole H1 provided in a floor slab S1 forming an existing structure C comprises a fixing jig 23 including a plurality of divided plates 21 that are foldably connected, a fixed part 23a fixed to an upper surface of the divided plate 21, and a rotating part 23b that rotates with respect to the fixed part 23a, and a hanging member 33 attached to one end of an intermediate member 31 attached to one end of the rotating part 23b. The plane dimensions of the plurality of divided plates 21 are larger than the plane dimensions of the through hole H1. When the hanging member 33 is pulled upward, the upper surfaces of the plurality of divided plates 21 come into contact with the lower surface of the floor slab S1, thereby closing the lower opening of the through hole H1.SELECTED DRAWING: Figure 19B

Description

Technical Field

[0001] The present invention relates to a bottom cover for closing through holes in a floor slab and a method for closing through holes in a floor slab.

Background Art

[0002] There are cases where ground improvement is carried out below an existing structure existing in a river, sea area, ground below the groundwater level, etc. (in this specification, these regions are collectively referred to as "water areas"). For example, in a box culvert that forms a main line for taking in and circulating rainwater and sewage, when a new structure is constructed above the box culvert, it is necessary to enhance the ground strength under the box culvert. Therefore, ground improvement is constructed under the box culvert while supplying the main line for rainwater and sewage. When constructing ground improvement under an existing structure in a water area like this, when the width of the existing structure is long, there are limitations to the method of inserting improvement rods obliquely from the side of the existing structure, and there is a risk of areas that cannot be improved. Therefore, construction can be carried out by forming through holes in the upper floor slab and lower floor slab that make up the existing structure, and inserting improvement rods into the ground under the existing structure through each through hole to perform ground improvement.

[0003] In this construction method, since it is ground improvement under an existing structure in a water area, when through holes are formed in the upper floor slab and lower floor slab of the existing structure, it is important to take water-stop measures to prevent groundwater from infiltrating into the main line or, conversely, to prevent sewage, etc. from leaking into the ground. However, if there is a space for flowing sewage, rainwater, etc. in the existing structure, and this space is below the floor slab with through holes formed, and it is a narrow space where people cannot enter, when closing the through holes with a closing material such as mortar, a bottom cover for closing the lower opening of the through hole on the lower surface of the floor slab cannot be installed, and the through holes cannot be closed. Therefore, leakage of sewage, etc. can become a problem.

[0004] Here, Patent Document 1 proposes a method for installing a bottom door in which the shaft connection hole of a caisson is sealed by the ceiling slab of the workroom. Specifically, the caisson is provided with an insertion hole for an operating chain that connects the shaft connection hole and the workroom, a blind cover is detachably provided to seal and close the workroom side of the insertion hole, a chain block is suspended inside a special shaft or cascaded shaft connected to the shaft connection hole, the operating chain of the chain block is inserted through the insertion hole and the end is allowed to hang down into the workroom, the bottom door is lifted up by operating this operating chain until it is pressed against the ceiling slab of the workroom, the part of the operating chain hanging down into the workroom is placed inside the insertion hole, and the insertion hole on the workroom side is sealed with the blind cover. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2000-291017 [Overview of the project] [Problems that the invention aims to solve]

[0006] According to the method for installing the bottom door of a caisson described in Patent Document 1, the installation (sealing) of the bottom door can be performed by two workers, one inside the caisson work area and the other inside the shuttle connection hole, and the work can be performed more quickly and safely than in the conventional method. However, as described above, when closing through holes formed in the floor slab of an existing structure, there is no disclosure of means for closing the lower opening of the through hole on the underside of the floor slab when the space below the floor slab is a narrow space inaccessible to a person.

[0007] The present invention aims to provide a bottom cover for closing through holes formed in the floor slab of an existing structure, and a method for closing through holes in a floor slab, which can close the lower opening of the through hole on the underside of the floor slab even if the space below the floor slab is a narrow space inaccessible to a person. [Means for solving the problem]

[0008] To achieve the above objective, one embodiment of a bottom cover for closing through holes in a floor slab according to the present invention is: A bottom cover for closing through holes provided in the floor slab forming an existing concrete structure, Multiple divided plates that are connected to each other in a way that allows them to be folded, A fixing jig comprising a fixing part fixed to the upper surface of the dividing plate and a rotating part that rotates relative to the fixing part, It has a suspension member attached to one end of the rotating part, or to one end of an intermediate member attached to one end of the rotating part, The planar dimensions of the plurality of divided plates are larger than the planar dimensions of the through holes. The suspension member is characterized in that when it is pulled upward, the upper surfaces of the plurality of divided plates come into contact with the lower surface of the floor slab, thereby closing the lower opening of the through hole.

[0009] According to this embodiment, by providing a plurality of segmented plates that are foldable and connected to each other, the planar dimensions of the bottom cover when passing through the through hole can be adjusted to a size that allows it to pass through the through hole. Therefore, when closing the through hole, the bottom cover, which has a planar dimension larger than the through hole, can be folded and suspended below through the through hole. Furthermore, when the plurality of segmented plates protrude from the through hole, the whole spreads out laterally, making the planar dimensions of the bottom cover larger than the planar dimensions of the through hole. This allows the bottom cover to be lifted up and the peripheral area of ​​the bottom cover to be in close contact with the underside of the floor slab, thereby closing the lower opening of the through hole. In other words, by applying the bottom cover of this embodiment, even if the space below the floor slab is a narrow space inaccessible to people, it becomes possible to close the lower opening of the through-hole formed in the floor slab with the bottom cover and close the through-hole with a sealing material.

[0010] Here, the "intermediate member" is, for example, a steel rod approximately the length of the through-hole. One end of the steel rod is fixed to the rotating part, and one end of the suspension member is fixed to the other end of the steel rod via a nut, including a tall nut. As the sealing material hardens, the intermediate member inside the through-hole is embedded in the sealing material, and the sealing of the through-hole can be completed by removing one end of the suspension member from the tall nut, etc., located above the intermediate member.

[0011] Although it is possible to omit the intermediate member and fix one end of the suspension member to the rotating part, in this case, the suspension member cannot be removed from the rotating part due to the hardening of the sealing material, and part or all of the suspension member will be left protruding above the floor slab. Therefore, it is preferable to apply an intermediate member having a length approximately equal to the thickness of the through hole. Here, steel bars, chains, and the like can be used as suspension members.

[0012] Furthermore, another embodiment of the bottom cover for closing through holes in the floor slab according to the present invention is: A sealing material is provided on the upper surface of the plurality of divided plates, which closes or surrounds the lower opening of the through hole and adheres tightly to the lower surface of the floor slab.

[0013] According to this embodiment, by providing a sealing material on the upper surface of multiple divided plates that closes or surrounds the lower opening of the through hole and adheres tightly to the lower surface of the floor slab, it is possible to ensure watertightness between the area around the lower opening of the through hole in the floor slab and the bottom cover.

[0014] Furthermore, another embodiment of the bottom cover for closing through holes in the floor slab according to the present invention is: The above-mentioned multiple divided plates are characterized in that multiple alignment pins protruding upward are provided at multiple locations on the upper surface of the multiple divided plates corresponding to the downward opening of the through-hole, and these multiple alignment pins are fitted into the through-hole.

[0015] According to this aspect, among the upper surfaces of the plurality of dividing plates, a plurality of alignment pins protruding upward are provided at a plurality of locations corresponding to the lower openings of the through holes. When the plurality of dividing plates are lifted by the suspension members, the plurality of alignment pins protruding upward fit into the lower openings of the through holes, enabling the plurality of dividing plates to be efficiently arranged at predetermined positions on the lower surface of the floor slab.

[0016] Further, another aspect of the bottom cover for closing the through hole of the floor slab according to the present invention is characterized in that a counterweight is attached at a position offset from the center of gravity position of the plurality of dividing plates.

[0017] [[ID= 10]]According to this aspect, since a counterweight is attached at a position offset from the center of gravity position of the plurality of dividing plates, the posture of the plurality of dividing plates when passing through the through hole can be set to an inclined posture, and the planar dimension when the dividing plates pass through can be made even smaller.

[0018] Further, one aspect of the method for closing the through hole of the floor slab according to the present invention is a method for closing the through hole of the floor slab for repairing by closing the through hole provided in the floor slab forming an existing concrete structure, a plurality of dividing plates that are foldably connected to each other, a fixing jig including a fixing portion fixed to the upper surface of the plurality of dividing plates and a rotating portion that rotates with respect to the fixing portion, having a suspension member attached to one end of the rotating portion or one end of an intermediate member attached to one end of the rotating portion, a preparation step of preparing a bottom cover in which the planar dimensions of the plurality of dividing plates are larger than the planar dimensions of the through hole, an opening closing step of inserting the plurality of dividing plates in a folded state through the through hole from above the through hole, pulling up the suspension member upward, bringing the upper surface of the plurality of dividing plates into contact with the lower surface of the floor slab, and closing the lower opening of the through hole, characterized by having a through hole closing step of filling the through hole with a closing material to close the through hole.

[0019] According to this aspect, by applying a bottom cover provided with a plurality of divided plates that are foldably connected to each other, when closing the through hole, the bottom cover having a planar dimension larger than the through hole can be suspended below through the through hole in a folded state, and when the plurality of divided plates protrude from the through hole, the whole can expand sideways, so that the planar dimension of the bottom cover can be made larger than the planar dimension of the through hole to close the lower opening of the through hole. Therefore, even if the space below the floor slab is a narrow space where people cannot enter, the lower opening of the through hole formed in the floor slab can be closed with the bottom cover, and the through hole can be closed with a closing material.

Effect of the Invention

[0020] According to the bottom cover for closing the through hole of the floor slab of the present invention and the method for closing the through hole of the floor slab, when closing the through hole formed in the floor slab of an existing structure, even if the space below the floor slab is a narrow space where people cannot enter, the lower opening of the through hole can be closed on the lower surface of the floor slab.

Brief Description of the Drawings

[0021] [Figure 1] It is a view showing an example of an existing structure in a water area to which the ground improvement method under an existing structure is applied. [Figure 2] It is a process diagram of an example of the ground improvement method under an existing structure. [Figure 3] Following Figure 2, it is a process diagram of an example of the ground improvement method under an existing structure. [Figure 4] Following Figure 3, it is a process diagram of an example of the ground improvement method under an existing structure. [Figure 5] Following Figure 4, it is a process diagram of an example of the ground improvement method under an existing structure. [Figure 6] It is a view for explaining an example of a fall prevention jig, showing both the state where the fall prevention jig passes through the through hole and the state where it protrudes from the through hole. [Figure 7] Following Figure 5, it is a process diagram of an example of the ground improvement method under an existing structure. [Figure 8]Following Figure 7, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 9] Following Figure 8, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 10] Following Figure 9, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 11] Following Figure 10, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 12] Following Figure 11, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 13] Following Figure 12, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 14] Following Figure 13, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 15] Following Figure 14, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 16] Following Figure 15, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 17] Following Figure 16, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 18] Following Figure 17, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 19A] This is a perspective view of an example of a bottom cover for closing through holes in a floor slab according to an embodiment. [Figure 19B] This figure illustrates an example of a method for closing through holes in a floor slab according to an embodiment, and shows both the state in which the bottom cover passes through the through hole and the state in which it is in close contact with the lower surface of the floor slab. [Figure 20] Following Figure 18, this is a process diagram illustrating an example of a ground improvement method for existing structures. [Figure 21A] This is a process diagram explaining the test construction. [Figure 21B] Following Figure 21A, this is a process diagram explaining the test construction. [Figure 21C] Following Figure 21B, this is a process diagram explaining the test construction. [Figure 21D]Following Figure 21C, this is a process diagram explaining the test construction. [Figure 21E] Following Figure 21D, this is a process diagram explaining the test construction. [Figure 21F] Following Figure 21E, this is a process diagram explaining the test construction. [Figure 21G] Following Figure 21F, this is a process diagram explaining the test construction. [Figure 21H] Following Figure 21G, this is a process diagram explaining the test construction. [Modes for carrying out the invention]

[0022] The following describes a bottom cover for closing through holes in a floor slab and a method for closing through holes in a floor slab according to an embodiment, with reference to the attached drawings. In this specification and drawings, substantially identical components are denoted by the same reference numerals to avoid redundant explanations.

[0023] [Method for improving the ground beneath an existing structure, a bottom cover for closing through holes in a deck slab according to the embodiment, and a method for closing through holes in a deck slab] Referring to Figures 1 to 20, an example of a ground improvement method beneath an existing structure will be described, and within this, referring to Figures 19A and 19B, an example of a bottom cover for closing through holes in a deck slab according to the embodiment, and an example of a method for closing through holes in a deck slab will be described. Here, Figure 1 is a diagram showing an example of an existing structure located in a body of water to which a ground improvement method for existing structures is applied, and Figures 2 to 5, 7 to 18, and 20 are, in order, process diagrams of an example of a ground improvement method for existing structures. Figure 6 is a diagram illustrating an example of a fall prevention jig, showing both the state in which the fall prevention jig passes through the through hole and the state in which it protrudes from the through hole. Furthermore, Figure 19A is a perspective view of an example of a bottom cover for closing a through hole in a deck slab according to the embodiment, and Figure 19B is a diagram illustrating an example of a method for closing a through hole in a deck slab according to the embodiment, showing both the state in which the bottom cover passes through the through hole and the state in which it is in close contact with the underside of the deck slab.

[0024] The existing structure C, which is the target of the ground improvement work shown in Figure 1, is a linear, reinforced concrete box culvert embedded in the ground G beneath the riverbed. This box culvert C has an upper slab S1 (an example of a slab), a lower slab S3, and left and right side walls W1, and has a partition wall W2 inside, with an intermediate slab S2 further located in the area to the right of the partition wall W2.

[0025] The space (hollow) between the upper slab S1 and the middle slab S2 is the sewer main space C1, the space between the middle slab S2 and the lower slab S3 is the management space C2, and the space in the left region of the partition wall W2 is the rainwater main space C3.

[0026] Furthermore, the sewer main space C1 is a narrow space inaccessible to people, and sewer water flows through it at all times. On the other hand, the management space C2 is accessible to administrators and is used for managing the sewer and rainwater main lines. The method for performing ground improvement on the ground G1 below this box culvert C will be explained below.

[0027] In detail, the ground G1 below the rainwater main space C3 and the ground below the management space C2 will be improved separately, but the following explanation will focus on the method of improving the ground G1 below the management space C2. The ground improvement of the ground G1 below the rainwater main space C3 will be carried out using substantially the same method. Note that the existing structure whose ground below is subject to improvement is not limited to the box culvert shown in the illustration, but can include various concrete structures. In addition, the body of water where the ground to be constructed is located may be a river as shown in the illustration, or it may be a sea area. Furthermore, the existing structure may be an underwater structure that protrudes into the water, and the ground below it may be subject to improvement.

[0028] In Figures 2 and beyond, only the right-hand region of the bulkhead W2 under construction is shown. Furthermore, to facilitate understanding of the drawings, the sewer lines in the sewer main space C1 are omitted from the illustration. Additionally, a work platform exists above the river in the box culvert C. Drilling equipment such as boring machines are installed on this work platform to perform rotary press-in of the first penetration rod R1, and similarly, ground improvement is carried out using ground improvement equipment installed on the work platform. However, the illustrations of this work platform, drilling equipment, and ground improvement equipment are omitted.

[0029] As shown in Figure 2, the first penetration rod R1 is driven in the X2 direction while rotating in the X1 direction from above the upper slab S1 to a point midway through the thickness of the upper slab S1. As an example, a φ406 mm casing can be applied to the first penetration rod R1.

[0030] By rotating and pressing the first penetration rod R1 into the upper slab S1 to an intermediate position without water and then curing it, a watertight structure (primary watertight structure) is formed between the first penetration rod R1 and the upper slab S1. For example, if the thickness of the upper slab S1 is about 500 mm, the first penetration rod R1 is driven in about 50 mm.

[0031] Next, as shown in Figure 3, non-shrink mortar M1 (an example of a waterproofing material) is filled into the interior of the first penetration rod R1. After filling with non-shrink mortar M1, the first penetration rod R1 is slightly pulled up, causing the non-shrink mortar M1 to spread outward through the penetration groove formed by the first penetration rod R1. Subsequently, by lowering the first penetration rod R1 and returning its tip to the penetration groove, a waterproofing structure (secondary waterproofing structure) is formed, as shown in Figure 3, in which the areas inside and outside the first penetration rod R1 are waterproofed with non-shrink mortar M1.

[0032] In this way, by forming a watertight structure (secondary watertight structure) using non-shrink mortar M1, the intrusion of groundwater into the interior of the first penetration rod R1 can be suppressed in combination with the primary watertight structure described above (the above describes the upper deck penetration process).

[0033] Next, as shown in Figure 4, a relatively small-diameter single pipe P is inserted into the first penetration rod R1 in the X3 direction, and a pilot hole Ha is formed by drilling through the upper deck slab S1.

[0034] As shown in Figure 5, a fall prevention jig 10 is inserted into the pre-hole Ha in the X4 direction, and its lower part is extended out through the pre-hole Ha into the sewer main space C1.

[0035] Here, with reference to Figure 6, the configuration and operation of the fall prevention jig 10 will be explained. The fall prevention jig 10 is a jig that prevents the concrete core CO generated when forming a through hole H1 (the first through hole H1 shown in Figure 7) in the upper floor slab S1 from falling onto the upper surface of the middle floor slab S2.

[0036] The fall prevention jig 10 includes, for example, a metal rod 11 and a plurality of metal diameter-expanding members 15 that are rotatably attached to the rod 11.

[0037] The rod 11 is formed from a hollow pipe, and three storage grooves 11a are provided at the left and right positions along its longitudinal direction. The lower ends of two diameter-expanding members 15 are rotatably mounted on a pivot shaft 13 located inside the rod 11, and each diameter-expanding member 15 is constantly biased to expand relative to the rod 11 via an elastic material 16 such as a coil spring.

[0038] In the illustrated example of the fall prevention jig 10, a pair of diameter-expanding members 15 are rotatably attached to three locations along the longitudinal direction of the rod 11.

[0039] When the fall prevention jig 10 passes through the pre-hole Ha made of the single pipe P, as shown in Figure 6, at least a portion of each enlarged diameter member 15 is housed in the housing groove 11a of the rod member 11, becoming the fall prevention jig 10A in a reduced diameter position, and is inserted through the inside of the single pipe P in the downward direction X4.

[0040] On the other hand, when the lower part of the fall prevention jig 10 extends below the single pipe P (below the upper floor slab S1), the diameter-expanding member 15, which is constantly biased to expand by the elastic material 16, rotates in the X5 direction via the pivot axis 13 and expands outward, and the pair of diameter-expanding members 15 expand to a larger diameter than the preceding guide hole Ha, resulting in the fall prevention jig 10B in an expanded diameter position.

[0041] Thus, when the fall prevention jig 10 is inserted into the preceding guide hole Ha, it is in a reduced diameter position as the fall prevention jig 10A, and when it extends below the upper floor slab S1, it changes its position to an expanded diameter position as the fall prevention jig 10B.

[0042] Here, a pair of diameter-expanding members 15 are rotatably provided at multiple different positions (three in the illustrated example) along the longitudinal direction (height direction) of the rod 11. For example, if the pair of diameter-expanding members 15 at the top malfunction and fail to expand, the pair of diameter-expanding members 15 in the center can expand and support the falling concrete core CO. Also, if the pair of diameter-expanding members 15 in the center are damaged or otherwise fail to expand during use, the pair of diameter-expanding members 15 at the bottom can expand and support the falling concrete core CO.

[0043] In this way, by providing multiple sets of diameter-expanding members 15 rotatably at different height positions on the rod member 11, even if some of the diameter-expanding members 15 malfunction or break, the concrete core CO can be reliably supported by the other sets of diameter-expanding members 15.

[0044] Furthermore, the process of preparing this fall prevention jig 10 is a preparation process (fall prevention jig preparation process), and the process of forming the pre-hole Ha in the upper floor slab S1 is a pre-hole formation process.

[0045] Figure 5 shows the state in which the lower part of the fall prevention jig 10 protrudes into the sewer main space C1, resulting in the fall prevention jig 10B in an expanded diameter position.

[0046] Next, as shown in Figure 7, the first drilling rod R2 is positioned inside the first penetration rod R1 in the upper slab S1, and the first drilling rod R2 is rotated in the X6 direction while drilling through in the X7 direction. As an example, a φ355 mm casing can be applied to the first drilling rod R2.

[0047] By drilling a first drilling rod R2 through the upper slab S1, a first through-hole H1 is formed in the upper slab S1, and a concrete core CO is generated during the formation of the first through-hole H1. By supporting the generated concrete core CO with an expanded-diameter fall prevention jig 10B, it is possible to prevent the concrete core CO from falling onto the upper surface of the middle slab S2. Thus, the process of forming the first through-hole H1 and supporting and recovering the concrete core CO with the expanded-diameter fall prevention jig 10B constitutes the through-hole formation process.

[0048] As previously mentioned, the sewer main space C1 is a narrow space inaccessible to people, making it impossible to recover the concrete core CO if it falls onto the upper surface of the intermediate slab S2. Thus, the fall prevention jig 10 is effective when forming a through hole in the slab (upper slab S1) above a narrow space inaccessible to people.

[0049] Furthermore, by forming the preliminary guide hole Ha with the smallest possible diameter, the first drilling rod R2 can be positioned between the pipe P forming the preliminary guide hole Ha and the first penetration rod R1 to form the first through hole H1. Even when a pipe P forming a small-diameter preliminary guide hole Ha is used, the fall prevention jig 10 can pass through the inside of the small-diameter pipe P by changing its orientation to a reduced-diameter fall prevention jig 10A (the above describes the upper slab penetration process).

[0050] Next, as shown in Figure 8, the first drilling rod R2 is used as the second penetration rod, and the second penetration rod R2 is driven in the X9 direction while rotating it in the X8 direction from above the subfloor slab S2 to a position midway through the thickness of the subfloor slab S2. Here, as shown in the illustrated example, instead of using the first drilling rod R2 as the second penetration rod, a second penetration rod different from the first drilling rod R2 may be used.

[0051] By rotating and pressing the second penetration rod R2 into the intermediate slab S2 in a waterless state up to an intermediate position and then curing it, a watertight structure (primary watertight structure) is formed between the second penetration rod R2 and the intermediate slab S2. For example, if the thickness of the intermediate slab S2 is about 500 mm, the second penetration rod R2 is driven in about 50 mm.

[0052] Next, as shown in Figure 9, non-shrink mortar M2 (an example of a waterproofing material) is filled into the interior of the second penetration rod R2. After filling with non-shrink mortar M2, the second penetration rod R2 is slightly lifted, causing the non-shrink mortar M2 to spread outward through the penetration groove formed by the second penetration rod R2. Subsequently, by lowering the second penetration rod R2 and returning its tip to the penetration groove, a waterproofing structure (secondary waterproofing structure) is formed, as shown in Figure 9, where the areas inside and outside the second penetration rod R2 are waterproofed with non-shrink mortar M2. Note that since sewage is present in the sewer main space C1, if it is not possible to slightly lift the second penetration rod R2 in this manner, it is not necessary to lift the second penetration rod R2.

[0053] In this way, by forming a watertight structure (secondary watertight structure) using non-shrink mortar M2, the intrusion of sewage into the interior of the second penetration rod R2 can be suppressed in combination with the primary watertight structure described above (the above describes the intermediate floor slab penetration process).

[0054] Next, as shown in Figure 10, a second drilling rod R3 is placed inside the second penetration rod R2 in the subfloor slab S2, and the second drilling rod R3 is rotated in the X10 direction while drilling through in the X11 direction. As an example, a φ318 mm casing can be applied to the second drilling rod R3.

[0055] By drilling through the intermediate slab S2 with the second drilling rod R3, a second through-hole H2 is formed in the intermediate slab S2, and concrete core CO is generated during the formation of the second through-hole H2. The generated concrete core CO falls onto the upper surface of the lower slab S3. However, since the management space C2 is large enough for a person to enter, the fallen concrete core CO can be collected by a worker.

[0056] If it is desired to prevent the concrete core CO from falling, a preliminary guide hole can be formed in the sub-slab S2 before the second drilling rod R3 is drilled through, using the same method as in Figures 4 and 5, and the fall prevention jig 10 can be applied (this completes the sub-slab penetration process).

[0057] Next, as shown in Figure 11, the second drilling rod R3 is used as the third penetration rod and is driven in the X13 direction from above the lower slab S3 to a point midway through the thickness of the lower slab S3 while rotating the third penetration rod R3 in the X12 direction. Here, as shown in the illustrated example, instead of using the second drilling rod R3 as the third penetration rod, a third penetration rod different from the second drilling rod R3 may be used.

[0058] By rotating and pressing the third penetration rod R3 into the lower slab S3 in a waterless state up to an intermediate position and then curing it, a watertight structure (primary watertight structure) is formed between the third penetration rod R3 and the lower slab S3. For example, the third penetration rod R3 is driven in about 50 mm.

[0059] Next, as shown in Figure 12, non-shrink mortar M3 (an example of a waterproofing material) is filled into the interior of the third penetration rod R3. After filling with non-shrink mortar M3, the third penetration rod R3 is slightly pulled up, causing the non-shrink mortar M3 to spread outward through the penetration groove formed by the third penetration rod R3. Subsequently, by lowering the third penetration rod R3 and returning its tip to the penetration groove, a waterproofing structure (secondary waterproofing structure) is formed, as shown in Figure 12, in which the areas inside and outside the third penetration rod R3 are waterproofed with non-shrink mortar M3.

[0060] In this way, by forming a watertight structure (secondary watertight structure) using non-shrink mortar M3, in combination with the primary watertight structure described above, it is possible to prevent groundwater that has seeped in from below the lower slab S3 from entering the management space C2 when a through hole (third through hole) is formed in the lower slab S3 (this concludes the lower slab penetration process).

[0061] Next, as shown in Figure 13, the third drilling rod R4 is positioned inside the third penetration rod R3 in the lower slab S3, and the third drilling rod R4 is rotated in the X14 direction while drilling through in the X15 direction. As an example, a φ267mm casing can be applied to the third drilling rod R4.

[0062] By drilling through the lower slab S3 with the third drilling rod R4, a third through-hole H3 is formed in the lower slab S3. If it is desired to recover the concrete core generated during the formation of the third through-hole H3, a preliminary guide hole can be formed in the lower slab S3 before drilling through with the third drilling rod R4, using the same method as in Figures 4 and 5, and the fall prevention jig 10 can be inserted into the ground G1 below (this concludes the lower slab penetration process).

[0063] By sequentially executing the above steps, the first through-hole H1, the second through-hole H2, and the third through-hole H3 are formed at vertically corresponding positions in the upper slab S1, the middle slab S2, and the lower slab S3.

[0064] Next, a wing bit of, for example, φ250 mm is inserted into the ground G1 below the box culvert C through the first through-hole H1, the second through-hole H2, and the third through-hole H3 from above, and by excavating to the ground improvement depth, an installation hole Hg for installing the improvement rod Ra is created, as shown in Figure 14.

[0065] Next, as shown in Figure 14, while lifting and removing the third drilling rod R4, the improvement rod Ra is inserted in the X16 direction to the installation hole Hg, and the improvement rod Ra is installed at the ground improvement depth. Then, while rotating the improvement rod Ra, a slurry of (ultra) high pressure and (large) flow rate is injected laterally in the X17 direction from its tip, performing a (ultra) large-diameter high-pressure injection mixing method (an example of ground improvement).

[0066] This high-pressure injection mixing method creates, for example, a large-diameter pile ground improvement body GI in the ground G1 below the lower slab S3 in the right-hand region of the bulkhead W2 of the box culvert C, as shown in Figure 15.

[0067] Here, in addition to the illustrated example, other ground improvement methods such as chemical grouting methods that can be used to perform ground improvement by applying the improvement rod Ra may also be applied (ground improvement process).

[0068] After constructing the ground improvement body GI, a φ250mm wing bit or similar is reinserted into the third through-hole H3, and the ground improvement body that has entered the third through-hole H3 is re-drilled to clean the inside of the hole.

[0069] Next, a fiberscope is inserted into the third through-hole H1 to check the construction status of the ground improvement body GI. Then, as shown in Figure 16, the second drilling rod R3 is withdrawn and removed, and non-shrink mortar M4 (an example of a sealing material) is filled into the third through-hole H3 of the lower slab S3. The top cover L1 is then placed on the upper surface of the lower slab S3 to seal the non-shrink mortar M4, and the top cover L1 is fixed to the lower slab S3 with anchor bolts A. Here, although not shown in the illustration, it is desirable to ensure watertightness by interposing a packing between the upper surface of the lower slab S3 and the top cover L1.

[0070] Next, the second through-hole H2 on the underside of the intermediate floor slab S2 is closed with the lower cover L2, and the lower cover L2 is fixed to the intermediate floor slab S2 with anchor bolts A. The lower cover L2 can be attached to the underside of the intermediate floor slab S2 by a worker from inside the management space C2. Here, although not shown in the diagram, it is desirable to ensure watertightness by interposing a packing between the underside of the intermediate floor slab S3 and the lower cover L2.

[0071] Next, as shown in Figure 17, while the first drilling rod R2 is withdrawn and removed, non-shrink mortar M5 (an example of a sealing material) is filled into the second through-hole H2 through the filling hole provided in the lower cover L2, thereby sealing the second through-hole H2.

[0072] Next, when closing the first through-hole H1 of the upper slab S1, workers cannot enter the sewer main space C1 and attach the bottom cover to the underside of the upper slab S1. Therefore, by applying the bottom cover 20 shown in Figures 19A and 19B, the area below the first through-hole H1 of the upper slab S1 is closed, as shown in Figure 18.

[0073] As shown in Figure 19A, the bottom cover 20 has a plurality (three in the illustrated example) of dividing plates 21A, 21B that are connected to each other in a foldable manner, a fixing jig 23 fixed to the upper surface of the central dividing plate 21A, and a suspension member 33 attached to the fixing jig 23 via an intermediate member 31. Here, the number of dividing plates may be two or four or more.

[0074] The fixing jig 23 comprises a fixing part 23a fixed to the central dividing plate 21A and a rotating part 23b that rotates relative to the fixing part 23a, with one end of the intermediate member 31 fixed to one end of the rotating part 23b. The fixing part 23a and the rotating part 23b can be formed by a knuckle joint.

[0075] For example, the upper end of the rotating part 23b has a screw groove, and one end of an intermediate member 31 of a predetermined length (for example, the length of the first through hole H1), made of, for example, a steel bar, is screwed into this screw groove. The other end of the intermediate member 31 is screwed into one end of a high nut 32, and one end of a suspension member 33, made of, for example, a steel bar, is screwed into the other end of the high nut 32. This suspension member 33 is suspended from a work platform or the like above the box culvert C.

[0076] The divided plates 21A and 21B are connected to each other by multiple hinges 22 (two in the illustrated example), and the left and right divided plates 21B rotate upward in the Y1 direction relative to the central divided plate 21A.

[0077] Furthermore, the three divided plates 21A and 21B have a circular shape in plan view, and the fixing part 23a is fixed to the centroid position T of the three divided plates 21A and 21B. Because the shape in plan view is circular, in the illustrated example, the fixing part 23a is fixed to the center of the circle.

[0078] On the other hand, in the illustrated example of the bottom cover 20, a counterweight 27 is attached to one side of the back surface of the divided plate 21A at an offset position. As shown in Figure 19B, when the bottom cover 20 is inserted through the first through hole H1, the left and right divided plates 21B come into contact with the wall surface of the first through hole H1 and rotate, rising towards the central divided plate 21A, and furthermore, the counterweight 27 rotates the entire three divided plates 21A and 21B around the rotating part 23b in the Y2 direction, resulting in an oblique position.

[0079] These measures make it possible to minimize the planar area of ​​the three divided plates 21A and 21B as they pass through the first through-hole H1, thereby facilitating their passage through the first through-hole H1.

[0080] Furthermore, as shown in Figure 19A, a sealing material 25 is provided on the upper surfaces of the three divided plates 21A and 21B to close or surround the lower opening of the first through hole H1 and to adhere tightly to the lower surface of the upper floor slab S1. Here, the sealing material 25 is made of a waterproof rubber sheet or the like.

[0081] Furthermore, on the upper surfaces of the three divided plates 21A and 21B, four alignment pins 26 are provided that protrude upward at multiple locations corresponding to the downward opening of the first through hole H1 (four locations on a virtual circle VC that simulates the downward opening of the first through hole H1).

[0082] As shown in Figure 19B, when the first through-hole H1 is inserted downward in the Y5 direction and the three divided plates 21A and 21B protrude below the lower surface of the upper floor slab S1, two of the divided plates 21B spread out to the sides. Subsequently, when the three divided plates 21A and 21B are lifted by the suspension member 33, the four alignment pins 26 that protrude upward fit into the downward opening of the first through-hole H1, thereby positioning the three divided plates 21A and 21B at predetermined positions on the lower surface of the upper floor slab S1.

[0083] This allows the sealant 25 to adhere tightly to the underside of the upper deck slab S1 while the lower opening of the first through hole H1 is closed by the three divided plates 21A and 21B. The tight adhesion of the sealant 25 to the underside of the upper deck slab S1 ensures watertightness.

[0084] Furthermore, the process of preparing this bottom cover 20 is a preparation process (bottom cover preparation process), and the process of closing the lower opening of the first through hole H1 with the three divided plates 21A and 21B is an opening closing process.

[0085] Following the opening closing process, the first through-hole H1 is filled from above with non-shrink mortar M6 (an example of a sealing material) via the first penetration rod to close it. Figure 20 shows the state after the first through-hole H1 has been closed with non-shrink mortar M6 and the first penetration rod R1 has been pulled up and removed.

[0086] Until the non-shrink mortar M6 achieves its predetermined strength, the three divided plates 21A and 21B are suspended from the work floor by the suspension member 33. As shown in Figure 20, an overcut portion M6a is provided above the non-shrink mortar M6, and as the overcut portion M6a hardens, it locks into the upper surface of the upper deck slab S1. The intermediate member 31 and the high nut 32 are embedded in the non-shrink mortar M6, and the frictional force of these and the locking structure of the overcut portion M6a maintain the close contact position of the three divided plates 21A and 21B with the lower surface of the upper deck slab S1, preventing the bottom cover 20 from falling off.

[0087] The tall nut 32 is located at the upper end of the non-shrink mortar M6, and after the non-shrink mortar M6 has developed its strength, the suspension member 33 can be rotated to remove it from the tall nut 32 and retrieve it. Alternatively, the tall nut 32 may be positioned on the outside of the non-shrink mortar M6, and the suspension member 33 and tall nut 32 may be rotated together to remove them from the intermediate member 31 and retrieve them (this completes the through-hole closing process).

[0088] Thus, in this method of performing ground improvement on the ground G1 below the box culvert while forming through holes in each of the multiple slabs constituting the box culvert C, it becomes possible to perform ground improvement while preventing both the leakage of sewage and other contents into the ground G within the box culvert C and the infiltration of groundwater into the box culvert C.

[0089] [Test construction] Next, the test construction carried out by the inventors will be described with reference to Figures 21A to 21H. Here, Figures 21A to 21H are, in order, process diagrams of the test construction.

[0090] First, as shown in Figure 21A, a concrete slab was fabricated. The fabricated concrete slab was supported by two H-shaped steel beams and raised by 0.3 m. A test pressure box was installed on the top surface of the concrete slab via a packing and secured with anchor bolts.

[0091] Next, as shown in Figure 21B, a work platform was set up around the concrete slab, and a boring machine was installed on it. This work platform simulates an actual work platform.

[0092] Next, as shown in Figure 21C, a φ400 mm casing was attached to the φ90 mm boring rod of the boring machine, and a hole was drilled in the concrete slab.

[0093] Next, as shown in Figure 21D, a φ400 mm casing was inserted into the upper 10 to 15 mm area of ​​a 500 mm thick concrete slab without water and fired, and non-shrink mortar was filled inside the casing.

[0094] Next, as shown in Figure 21E, the test pressure box and lid, and the lid and a φ400mm casing were fixed in place to seal the connection, and pressurized water at 0.2 MPa was supplied from the ball valve section. This simulates the water pressure based on the actual groundwater level in the construction plan area.

[0095] Next, as shown in Figure 21F, a φ350mm casing was inserted into a φ400mm casing, and a hole was drilled through the concrete slab. The water leakage situation at that time was then observed. The observation revealed that no water leakage was detected under the condition of pressurized water at 0.2 MPa.

[0096] As shown in Figure 21G, a retrieval hinge for concrete core retrieval (to prevent it from falling) is attached to the lower inner end of the φ350mm casing, and the concrete core was retrieved simultaneously when the casing was lifted. This retrieval hinge simulates a fall prevention jig.

[0097] Next, as shown in Figure 21H, a steel plate was attached to the underside of the concrete slab to seal the through-hole, non-shrink mortar was filled into the φ400mm casing, and the φ400mm casing was removed to seal the through-hole.

[0098] This series of test constructions verified that, under conditions where a predetermined water pressure is applied, it is possible to achieve a series of construction methods that completely seal through-holes in concrete slabs with non-shrink mortar while preventing water leakage.

[0099] Furthermore, other embodiments may be used in which other components are combined with the configurations listed in the above embodiments, and the present invention is not limited in any way to the configurations shown herein. In this regard, modifications can be made without departing from the spirit of the present invention, and can be appropriately determined according to the application form. [Explanation of symbols]

[0100] 10: Fall prevention jig 10A: Drop prevention jig in reduced diameter position 10B: Fall prevention jig in expanded diameter position 11: Bar material 11a: Storage groove 13: Rotary shaft 15: Diameter-enlarged material 16: Elastic material 20: Bottom lid 21,21A,21B:Dividing plate 22: Hinge 23: Fixing jig 23a: Fixed part 23b: Rotating part 25: Sealant 26: Alignment pin 31: Intermediate member (steel bar) 32: High nut 33: Lifting member (steel bar) C: Existing structure (box culvert) C1: Main sewer space C2: Management space C3: Stormwater main space S1: Upper floor slab (floor slab) S2: Middle floor version S3: Lower floor version W1: Exterior wall W2: Bulkhead G: Ground G1: Lower ground (ground beneath existing structures) R1: First penetration rod R2: First drilling rod (second penetration rod) R3: Second drilling rod (third penetration rod) R4: Third drilling rod Ra: Improved rod P: Single tube M1, M2, M3: Water-stopping material (non-shrink mortar) M4, M5, M6: Sealing material (non-shrink mortar) M6a: Overcut section H1: 1st through hole (through hole) H2: 2nd through hole H3: 3rd through hole Ha: Leading hole Hg: Installation hole CO: Concrete Core GI: Ground improvement body L1: Upper lid L2: Lower lid A: Anchor bolt T: Center of gravity position VC: Virtual Yen

Claims

1. A bottom cover for closing through holes provided in the floor slab forming an existing concrete structure, Multiple divided plates that are connected to each other in a way that allows them to be folded, A fixing jig comprising a fixing part fixed to the upper surface of the dividing plate and a rotating part that rotates relative to the fixing part, A suspension member is attached to one end of the rotating part, or to one end of an intermediate member attached to one end of the rotating part, It has a counterweight attached at a position offset from the center of gravity of the plurality of divided plates, The planar dimensions of the plurality of divided plates are larger than the planar dimensions of the through holes. When the multiple divided plates are inserted through the through hole, the counterweight causes the multiple divided plates to rotate around the pivot point, resulting in an oblique position, and the planar area of ​​the multiple divided plates when they are inserted through the through hole is reduced compared to the state before rotation. A bottom cover for closing through holes in a floor slab, characterized in that when the suspension member is pulled upward, the upper surfaces of the plurality of divided plates come into contact with the lower surface of the floor slab, thereby closing the lower opening of the through hole.

2. The bottom cover for closing through holes in a floor slab according to claim 1, characterized in that a sealing material is provided on the upper surface of the plurality of divided plates, which closes or surrounds the lower opening of the through hole and adheres tightly to the lower surface of the floor slab.

3. A bottom cover for closing a through-hole in a floor slab, as described in claim 1 or 2, characterized in that multiple alignment pins protruding upward are provided at multiple locations on the upper surface of the multiple divided plates corresponding to the downward opening of the through-hole, and the multiple alignment pins are fitted into the through-hole.

4. A method for closing through holes in a concrete slab, which is used to repair existing concrete structures by closing the through holes in the slab, Multiple divided plates that are connected to each other in a way that allows them to be folded, A fixing jig comprising a fixing part fixed to the upper surface of the plurality of divided plates, and a rotating part that rotates relative to the fixing part, A suspension member is attached to one end of the rotating part, or to one end of an intermediate member attached to one end of the rotating part, It has a counterweight attached at a position offset from the center of gravity of the plurality of divided plates, A preparation step involves preparing a bottom cover in which the planar dimensions of the multiple divided plates are larger than the planar dimensions of the through-holes, With the plurality of divided plates folded, the through-hole is inserted from above, the suspension member is pulled upward, the upper surfaces of the plurality of divided plates are brought into contact with the lower surface of the floor slab, and the lower opening of the through-hole is closed in an opening closing step, The process includes a through-hole closing step of filling the through-hole with a sealing material to close the through-hole, In the aforementioned opening closing process, A method for closing a through-hole in a floor slab, characterized in that when inserting the plurality of divided plates into the through-hole, the plurality of divided plates are rotated around the pivot part by the counterweight to be in an oblique position, thereby reducing the planar area of ​​the plurality of divided plates when they are inserted into the through-hole compared to the state before rotation.

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