JP2020165152A - Deep foundation structure - Google Patents

Abstract

To provide a deep foundation structure with a waterproof countermeasure without increasing construction cost, while making backfilling of lightweight materials, a ground improvement and the like unnecessary.SOLUTION: Provided is a deep foundation structure 100 in which an inside steel formwork 60 remains to form a waterproof layer inside an erection portion 10 forming a reinforced concrete deep foundation 30, and an indoor space US exists in the waterproof layer.SELECTED DRAWING: Figure 1

Description

The present invention relates to a deep foundation structure.

As the foundation of a building, there is a height difference between the left and right grounds of the foundation, and when the foundation also serves as a retaining wall, a deep foundation is generally applied. By the way, for example, when a deep foundation is constructed on a soft ground with a ground bearing capacity of about 30 kN / m ² or less, the height of the backfill soil to be backfilled inside the deep foundation (inside the building) is 600 mm because of the deep foundation. Can be more than a degree. However, when backfilling soil with a height of about 600 mm or more is applied to the soft ground with a bearing capacity of about 600 mm or more, it is difficult to design with a direct foundation. Therefore, a lightweight material such as foamed plastic is used for the backfilled soil. Measures such as application, ground improvement and construction of piles directly below the foundation will be taken, both of which will cause the construction cost to rise.

In addition, the basement may be constructed using the above-mentioned deep foundation, but if the deep foundation is made of reinforced concrete, cracks are unavoidable in the reinforced concrete, so waterproof construction is unavoidable and the construction cost increases. This will lead to a longer construction period. Therefore, it is conceivable to apply a box-shaped steel basement that does not require waterproofing, but unlike ordinary reinforced concrete basements, the box-shaped steel basement is forced to be constructed by a specialized contractor, and from this point of view, the construction cost It leads to the soaring price of.

Therefore, in order to eliminate the need for backfilling of lightweight materials and ground improvement, it is preferable to construct a deep foundation made of reinforced concrete in a manner having an underground space. However, waterproof measures should be taken to prevent water (groundwater, rainwater, etc.) that has infiltrated from the back ground through cracks in the rising part made of reinforced concrete, for example, from leaking to the inner surface of the rising part that forms the underground space. There is no change in the need to take. Therefore, it is desired to develop a deep foundation with waterproof measures without increasing the construction cost.

By the way, regarding the floor structure of a building that uses both a general foundation and a deep foundation, it depends on a bundle erected on the soil concrete provided between the general foundations or between the general foundations and a large beam supported by the bundle. A floor structure of a building has been proposed in which a floor structure and a floor structure with beams erected between deep foundations are used in combination (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-125086

Even in the floor structure of the building described in Patent Document 1, it is said that the deep foundation is not backfilled and can be used in the underground space. Therefore, when constructing a deep foundation, it is possible to eliminate the need for backfilling of lightweight materials and ground improvement. However, since it is a deep foundation made of reinforced concrete, there is no change in the structure in which some kind of waterproof construction is unavoidable as a measure against water leakage caused by cracks as described above.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a deep foundation structure in which waterproof measures are taken without increasing the construction cost while eliminating the need for backfilling of lightweight materials and ground improvement. It is said.

In order to achieve the above object, one aspect of the deep foundation structure according to the present invention is
The inner steel formwork is left behind to form a waterproof layer inside the rising portion forming the deep foundation made of reinforced concrete, and the interior space exists in the waterproof layer.

According to this aspect, the inner steel formwork is left inside the rising portion forming the deep foundation to form a waterproof layer, so that the deep has a waterproof structure without any special waterproof construction. The foundation structure can be formed. That is, at the same time as the fresh concrete is hardened, the waterproof layer is formed by the remaining inner steel formwork, so that it is possible to provide a deep foundation structure in which waterproof measures are taken without increasing the construction cost. Further, "the indoor space exists in the waterproof layer" means that the indoor space is formed by not backfilling the inside of the deep foundation. Therefore, the deep foundation Even if the underlying ground is relatively soft, it is possible to eliminate the need for backfilling of lightweight materials and ground improvement.

When constructing a deep foundation made of reinforced concrete, the outer steel formwork (steel formwork is also called metal foam) and the inner steel formwork are assembled, and fresh concrete is poured into these formwork to make it fresh. After the concrete has hardened, only the outer steel formwork is removed. That is, in general, all the formwork of the outer formwork and the inner formwork is demolded. Alternatively, if necessary, the entire formwork may be filled up, in which case all the formwork of the outer formwork and the inner formwork is left behind. However, in the latter case, complete burying is a prerequisite, and a structure in which a part of the formwork is left as a waterproof measure, such as the inner steel formwork forming the deep foundation structure of this embodiment, is used. This is a new technical idea that does not exist in the past.

In this aspect, a steel formwork having excellent waterproofness is adopted because the formwork is left as a waterproof measure. Here, since the inner steel formwork is left behind and the outer steel formwork is demolded and diverted, the inner steel formwork may be formed from a steel formwork having relatively low specifications. ..

As for the bottom of the deep foundation, all of them may be made of reinforced concrete, or if the span between the opposing rising portions of the deep foundation is long, the bottom of the deep foundation is made of reinforced concrete in the range from the rising portion to a predetermined length. The structure may be such that the footing exists and the bottom plate (footing) made of reinforced concrete does not exist in the central region of the deep foundation. In the latter structure, soil concrete that extends over all the rising parts is constructed above the footing, but when constructing soil concrete, for example, a steel formwork is placed on the footing to make a steel mold. It is advisable to take measures to stop water from the bottom, such as constructing soil concrete above the frame.

The indoor space can be applied to an indoor warehouse, a basement, a deep bottom part of the first floor, which is continuous with the general part of the first floor, and which is lowered by about 30 cm to 200 cm from the general part of the first floor.

Further, in another aspect of the deep foundation structure according to the present invention, a beam is laid between the facing inner steel formwork inside the facing rising portion, and the first floor is supported by the beam. It is characterized by being.

According to this aspect, a plurality of beams are laid between the opposing inner steel formwork, a plurality of joists are fixed to the plurality of beams, and the first floor is supported by the plurality of joists. It is not necessary to support the first floor with a plurality of long bundles fixed to the bottom of the deep foundation, and the space under the beam can be provided to the basement or the like. For example, a plurality of short bundles can be fixed to the upper surface of the beam, and the first floor can be supported by the plurality of short bundles. Here, the beam may be a steel beam, an RC beam, or a wooden beam.

As an example of fixing the beam to the rising part, anchor bolts are joined by welding at the position corresponding to the beam on the side of the inner steel formwork of the rising part of the deep foundation to be embedded in the concrete, and inside the concrete. Be buried in the concrete. On the other hand, on the beam side of the inner steel formwork, a contact plate in which fixing bolts fixed to the beam are screwed is joined by welding, and the fixing bolts are projected toward the beam side. For example, the contact plate and the end plate are brought into contact with each other by inserting the tip of a fixing bolt into a bolt hole formed in the end plate of the end of a beam formed of H-shaped steel and tightening the nut. In the state of contact, the rising portion and the beam can be fixed via the fixing bolt and the anchor bolt.

Further, in another aspect of the deep foundation structure according to the present invention, the joint portion between the inner steel formwork is formed by tightening a bolt with a nut, and the bolt between the end faces of the inner steel formwork. It is characterized in that a waterproof material is arranged around it.

According to this aspect, the joints between the inner steel formwork are formed by bolts and nuts, and the water blocking material is arranged around the bolts between the end faces of the inner steel formwork. Prevents water flowing through cracks generated in the rising portion of the back surface of the inner steel formwork from leaking to the inside of the inner steel formwork through the joints between the inner steel formwork. be able to.

Further, in another aspect of the deep foundation structure according to the present invention, the inner steel formwork applied when the rising portion is formed and the outer steel formwork that is demolded after the rising portion is formed. The width stopper is embedded in the rising portion in a state where the width stopper to be connected is engaged with the engaged piece attached to the outer surface of the inner steel formwork.

According to this aspect, the engaging piece in which the width stopper metal fitting connecting the outer steel formwork and the inner steel formwork, which is removed after the rising portion is formed, is attached to the outer surface of the inner steel formwork. Since the width stopper does not penetrate the inner steel formwork by being engaged with the width stopper, it is possible to prevent water leakage to the inside of the inner steel formwork through the penetration portion of the width stopper.

In addition, another aspect of the deep foundation structure according to the present invention is characterized in that a plurality of hollow vertical ribs are attached to the inner surface of the inner steel formwork.

According to this aspect, a plurality of hollow vertical ribs provided on the inner surface of the inner steel formwork impart pressure resistance to the concrete pressure of fresh concrete to the inner steel formwork, and the hollow vertical ribs are provided. It can be applied as an attached member such as an inner decorative panel. Since the hollow vertical ribs are joined to the inner surface of the inner steel formwork by welding or the like, the inner steel formwork is not provided with a penetrating portion when the hollow vertical ribs are attached. There is no risk of water leakage through the part.

As can be understood from the above description, according to the deep foundation structure of the present invention, by having an indoor space, it is possible to eliminate the need for backfilling of lightweight materials, ground improvement, etc., and further, without increasing the construction cost. It is possible to provide a deep foundation structure with waterproof measures.

It is a vertical cross-sectional view of an example of the deep foundation structure which concerns on embodiment. It is an enlarged vertical sectional view of the joint part between the inner steel formwork. It is an enlarged vertical sectional view of the joint portion of a rising portion and a beam. It is a vertical cross-sectional view which shows the state before the rising part of a deep foundation structure is constructed. A vertical cross-sectional view showing a state in which the width stopper is embedded in the rising portion while being engaged with the back surface of the inner steel formwork, and also showing the removal of the fastener and the removal of the outer steel formwork. Is. It is a perspective view which shows the vertical rib attached to the inner surface of the inner steel formwork.

Hereinafter, the deep foundation structure according to the embodiment will be described with reference to the attached drawings. In the present specification and the drawings, substantially the same components may be designated by the same reference numerals to omit duplicate explanations.

[Deep foundation structure according to the embodiment]
An example of the deep foundation structure according to the embodiment will be described with reference to FIGS. 1 to 3. Here, FIG. 1 is a vertical cross-sectional view of an example of the deep foundation structure according to the embodiment, showing a part of the deep foundation. Further, FIG. 2 is an enlarged vertical cross-sectional view of the joint portion between the inner steel formwork, and FIG. 3 is an enlarged vertical cross-sectional view of the joint portion between the rising portion and the beam.

In the deep foundation structure 100, the inner steel formwork 60 is left inside the deep foundation 30 constructed for the terrain where the ground G on the left and right sides of the foundation has a height difference and the rising portion 10 forming the deep foundation 30. The inner steel formwork 60 forms an inner waterproof layer, and an indoor space US is formed in the waterproof layer 60.

Both the rising portion 10 and the footing 20 are made of reinforced concrete, and the deep foundation 30 resists earth pressure or earth water pressure. The footing 20 of the illustrated example forms a continuous bottom plate up to the rising portion 10 shown and the rising portion (not shown) facing the rising portion 10. The footing may be in the range from the rising portion 10 to a predetermined length, and may be footing that is not continuous to the facing rising portion (not shown).

A waste concrete layer 42 is formed on the crushed stone 41 laid on the root cutting surface at a predetermined depth of the ground G, and a footing 20 is formed on the waste concrete layer 42.

At an intermediate position of the rising portion 10, an inner steel formwork 60 applied when the rising portion 10 is formed and an outer steel formwork 65 (see FIG. 4) that is demolded after the rising portion 10 is formed. The width stopper 50 is embedded in the rising portion 10 in a state of being engaged with the engaged piece 62 attached to the outer surface of the inner steel formwork 60. Further, at the lowermost position of the rising portion 10, an inner steel formwork 60 applied when the rising portion 10 is formed and an outer steel formwork 65 that is demolded after the rising portion 10 is formed (FIG. The bottom connecting metal fitting 68 (see 4) is embedded in the rising portion 10 in a state of being engaged with the engaged piece 67 attached to the outer surface of the inner steel formwork 60.

As shown in FIG. 2, the joints between the inner steel formwork 60s are formed by fixing the bolts 91 with the tightening nuts 92, and are formed around the bolts 91 between the end faces of the inner steel formwork 60s. Is provided with, for example, a rubber water blocking material 93.

Further, as shown in FIG. 3, a plurality of anchor bolts 95a with heads are embedded at the installation position of the beam 70 above the rising portion 10, and the tip of each anchor bolt 95a is an inner steel formwork. It is fixed to the back surface of 60 via a welded portion 96.

The plurality of fixing bolts 95b are screwed into the bolt holes 94a of the contact plate 94 fixed to the inner surface of the inner steel formwork 60 via the welded portion 96, and further protrude inward.

The beam 70 is made of H-shaped steel, and an end plate 71 is joined to the end by welding. The tip of the fixing bolt 95b is inserted into the bolt hole 71a provided in the end plate 71, and the nut 95c The beam 70 is fixed to the rising portion 10 via the fixing bolt 95b and the anchor bolt 95a. The load loaded on the beam 70 from the first floor is transmitted to the inside of the rising portion 10 via the anchor bolt 95a.

Here, the beam 70 shown in the figure is formed of H-shaped steel or the like, but the beam 70 may be a steel beam such as a shaped steel material or a square steel pipe, or a reinforced concrete beam or a wooden beam. In addition to the mounting structure shown in FIG. 3, a gusset plate is joined to the contact plate 94 by welding, and an H-shaped steel web forming a beam having no end plate is bolted to the gusset plate. It may be in the form of being welded.

Returning to FIG. 1, a separate anchor bolt 83 extending in the vertical direction is embedded in the rising portion 10, and a part of the anchor bolt 83 projects upward from the top end surface of the rising portion 10. A bolt hole (not shown) provided in the base plate 82 is inserted into the anchor bolt 83 and fixed by tightening with a nut 88. Columns 81 made of H-shaped steel, square steel pipes, etc. that form the structural frame of the building are joined to the base plate 82 by welding. Therefore, the columns 81 are fixed to the top surface of the rising portion 10 via the base plate 82. Will be done.

As shown in FIG. 1, a plurality of joists 84 are fixed above the beam 70, and the first floor 85 is fixed and supported by the plurality of joists 84. As described above, the deep foundation structure 100 has an indoor space US below the beam 70 that supports the first floor 85, and the indoor space US is a basement for various purposes such as an underground living room and an underground storage room. Applies as. The deep foundation structure 100 does not include a beam 70 that supports the first floor 85. For example, the deep foundation structure 100 is continuous with the first floor general portion and is lowered by about 30 cm to 200 cm from the first floor general portion. It may be applied to the deep bottom of the floor. In this form, since the ceiling height is high at the deep bottom of the first floor, the deep bottom of the first floor can be used as a living room or the like with a feeling of openness.

Since the deep foundation structure 100 has an indoor space US inside, backfilling is not performed inside the deep foundation 30, so that the above-mentioned indoor space US can be effectively used, and backfill soil exists. Therefore, even if the ground G below the deep foundation 30 is relatively soft, it is possible to eliminate the need for backfilling of lightweight materials, ground improvement, and the like.

Next, a method of constructing the deep foundation structure 100 will be described with reference to FIGS. 4 and 5. Here, FIG. 4 is a vertical cross-sectional view showing a state before the rising portion of the deep foundation structure is constructed. Further, FIG. 5 shows a state in which the width stopper is embedded in the rising portion in a state of being engaged with the back surface of the inner steel formwork, and the fastening metal fitting is removed and the outer steel formwork is removed from the mold. It is a vertical cross-sectional view which shows both.

As shown in FIG. 4, in the construction of the deep foundation 30, first excavation to the root cutting surface of the ground G, the root cutting surface is leveled by rolling compaction or the like, crushed stone 41 is laid, and the discarded concrete layer 42 is constructed. .. Next, the formwork 66 for footing is assembled, the outer steel formwork 65 and the inner steel formwork 60 for the lower rising portion are assembled, and the bottom is connected to the engaged piece 67 on the back surface of the inner steel formwork 60. After engaging one end of the metal fitting 68 and engaging the other end of the bottom connecting metal fitting 68 with the outer steel formwork 65, concrete for footing is cast and the footing 20 is constructed in advance. The bottom connecting metal fitting 68 is not continuous in the depth direction of the paper surface, and has a space for filling concrete or inserting a vibrator.

Next, the outer steel formwork 65 and the inner steel formwork 60 extending to the top end of the rising portion 10 are assembled on the lower outer steel formwork 65 and the inner steel formwork 60 that have already been assembled. At the same time, at the intermediate positions of the outer steel formwork 65 and the inner steel formwork 60, both are width-fixed by the width stopper 50 to form a space SP for the rising portion.

Here, as shown in FIG. 5, the width stopper 50 is provided with an engaging piece 51 at one end thereof, and the hollow of the engaged piece 62 joined to the back surface of the inner steel formwork 60 by welding. By engaging the engaging piece 51 with, the width stopper 50 is locked to the back surface of the inner steel formwork 60. That is, the width stopper 50 is locked to the back surface of the inner steel formwork 60 without penetrating the inner steel formwork 60.

Returning to FIG. 4, the other end of the width stopper 50 has an engaging piece 52, the width stopper 50 is sandwiched between the upper and lower outer steel formwork 65, and the engaging piece 52 is the upper and lower outer steel formwork. By engaging with the outer surface of 65, the outer steel formwork 65 and the inner steel formwork 60 for the rising portion are assembled. Further, at the top ends of the outer steel formwork 65 and the inner steel formwork 60, a head connecting metal fitting 69 that engages with both is installed. The head connecting metal fitting 69 is not continuous in the depth direction of the paper surface, and has a space for filling concrete or inserting a vibrator. Then, the space SP for the rising portion is filled with fresh concrete, and the fresh concrete is hardened, so that the footing 20 and the rising portion 10 that have already been constructed are integrated to construct the deep foundation 30.

In this construction, the beam 70 can be made to function as a temporary cutting beam by bridging the beam 70 between the opposing rising portions 10 before filling the rising portion space SP with fresh concrete.

After the rising portion 10 is formed, as shown in FIG. 5, the outer steel formwork 65 is demolded in the X direction, and the outer circumference of the rising portion 10 is backfilled with earth and sand to form the pillar 81 and the pillar 81 shown in FIG. The deep foundation structure 100 is formed in the state before the first floor 85 is installed.

According to the deep foundation structure 100, after the rising portion 10 is constructed, a waterproof layer is automatically formed by leaving the inner steel formwork 60, so that special waterproof measures are taken over the construction cost and construction period. There is no need to take. The demolded outer steel formwork 65 is diverted as a separate formwork for concrete construction.

Further, since there is no water supply that communicates with the side surface of the rising portion 10 and penetrates the inner steel formwork 60, including the width stopper 50, it penetrates through, for example, a crack generated in the rising portion 10. Groundwater and rainwater are prevented from leaking from the inner steel formwork 60 to the indoor side. Further, as already described with reference to FIG. 2, since the water blocking material 93 is arranged around the bolt 91 at the joint portion between the inner steel formwork 60s, the inner steel formwork 60s are formed with each other. Water leakage to the indoor side through the joint of the steel is suppressed.

FIG. 6 is a perspective view showing a form in which vertical ribs are attached to the inner surface of the inner steel formwork. As shown in the illustrated example, on the inner surface of the inner steel formwork 60, vertical ribs 98 having a plurality of hollow 98a are attached via a plurality of welded portions 99 at intervals in the vertical direction, whereby fresh concrete. The pressure resistance to the concrete pressure can be imparted to the inner steel formwork 60. Further, the vertical rib 98 can be applied as a member to be attached to an inner decorative panel or the like (not shown). Further, by joining the hollow vertical ribs 98 to the inner surface of the inner steel formwork 60 via the plurality of welded portions 99, the through portion penetrates the inner steel formwork 60 when the hollow vertical ribs 98 are attached. Is not provided, and there is no risk of water leakage through the penetration part.

It should be noted that the configuration or the like described in the above embodiment may be another embodiment in which other components are combined, and the present invention is not limited to the configuration shown here. This point can be changed without departing from the spirit of the present invention, and can be appropriately determined according to the application form thereof.

10: Rising part, 20: Footing (bottom board), 30: Deep foundation, 50: Width stopper, 51, 52: Engagement piece, 60: Inner steel formwork (waterproof layer), 61: Folded piece, 62: Engagement piece, 65: Outer steel formwork, 66: Formwork, 67: Engagement piece, 68: Bottom bolt, 69: Head bolt, 70: Beam, 71: End plate, 81: Pillar, 84: Neta, 85: First floor, 88: Nut, 91: Bolt, 92: Tightening nut, 93: Water stop material, 94: Contact plate, 95a: Anchor bolt, 95b: Fixing bolt, 95c: Nut, 96 : Welded part, 98: Vertical rib, 98a: Hollow, 99: Welded part, 100: Deep foundation structure, G: Ground, US: Indoor space (underground room), SP: Space for rising part

Claims (5)

A deep foundation structure characterized in that an inner steel formwork is left behind to form a waterproof layer inside a rising portion forming a deep foundation made of reinforced concrete, and an indoor space exists in the waterproof layer. The first aspect of the present invention, wherein a beam is laid between the facing inner steel formwork inside the rising portion, and the first floor is supported by the beam. Deep foundation structure. The joint between the inner steel formwork is formed by tightening a bolt with a nut, and a water blocking material is arranged around the bolt between the end faces of the inner steel formwork. The deep foundation structure according to claim 1 or 2. The width stopper that connects the inner steel formwork applied when forming the rising portion and the outer steel formwork that is removed after the rising portion is formed is the outer surface of the inner steel formwork. The depth according to any one of claims 1 to 3, wherein the width stopper is embedded in the rising portion in a state of being engaged with the engaged piece attached to the above. Basic structure. The deep foundation structure according to any one of claims 1 to 4, wherein a plurality of hollow vertical ribs are attached to the inner surface of the inner steel formwork.

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