JP7333708B2 - Foundation structure and its construction method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foundation structure and its construction method, and more particularly to the structure of foundation beams.

Foundation beams are sometimes provided between the foundation piles of the building and the superstructure. Foundation beams are provided to transmit the weight of the superstructure and seismic loads to multiple foundation piles. In recent years, precast foundation beams (hereinafter referred to as PCa foundation beams) are sometimes used to shorten the construction period and improve quality (Patent Documents 1 and 2).

JP 2017-125322 A JP 2018-21445 A

Drainage pipes are installed inside the building in order to discharge the wastewater generated in the upper structure to the sewage system. Drainage piping extends from the superstructure to the underground space of the building and is connected to a sewage pipe buried outside the building. For this reason, drainage pipes sometimes penetrate foundation beams. Normally, the drainage pipe routing route is planned so as to ensure a favorable downward slope, and the position of the through-hole in the foundation beam is determined by the routing route. On the other hand, since PCa foundation beams are manufactured in a factory, it is necessary to complete the design, including the positions of through holes, several months before the installation work. However, the facility plan of the building may not be finalized until just before the start of construction, and since the foundation beams will be constructed early after the construction starts, there is a possibility that the positions of the through-holes will not be finalized at the time of designing the PCa foundation beams. To avoid such process mismatches, foundation beams have traditionally been constructed on site. That is, foundation beam reinforcement arrangement, through-hole sleeve setting, and concrete placement are performed on site. According to this method, the position and size of the through-holes in the foundation beams can be adjusted on site, so there is a low possibility of mismatches occurring in the process. As a result, however, there are cases where it is difficult to adopt precast structures, which are commonly used in superstructures, for foundation beams.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a precast basic structure capable of reducing the possibility of occurrence of process mismatch.

The basic structure of the flat collective housing of the present invention has a plurality of outer beams arranged along the outer periphery of the building and a plurality of inner beams provided inside the plurality of outer beams. The outer peripheral portion consists of one long side, the other long side, and a pair of short sides. Each of the plurality of inner beams is divided in the length direction of the inner beam into three parts, a precast part adjacent to one long side , a central precast part, and a cast-in-place part adjacent to the other long side. there is At least one first through- hole through which a drain pipe passes is provided only in the cast-in-place section , and a feed-through is provided only in the central precast section .

According to the present invention, the first through-hole through which the drainage pipe passes is provided only in the cast-in-place portion, so that the possibility of occurrence of mismatch in the process can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a front view of the plate-shaped housing complex to which this invention is applied. FIG. 2 is a plan view of the foundation beam viewed from line AA in FIG. 1; 1 is a perspective view of a foundation structure; FIG. FIG. 4 is an exploded perspective view of the foundation structure shown in FIG. 3; FIG. 3 is a cross-sectional view taken along line BB of FIG. 2; 3 is a cross-sectional view taken along line CC of FIG. 2; FIG. 3 is an enlarged view of part D in FIG. 2 showing a top view of the outer peripheral beam and the footing; FIG. 3 is a side view of the internal beam as seen from line EE of FIG. 2; FIG. It is a conceptual diagram explaining the process mismatch in a prior art. FIG. 6 is a view similar to FIG. 5 showing another embodiment of the invention;

An embodiment of the present invention will be described with reference to the drawings. Although the present invention can be applied to any building having foundation beams, a plate-like housing complex will be described here as an example. In the following description and drawings, the X direction is the girder direction of the plate-like apartment building, the Y direction is the direction between the beams of the plate-like apartment building, the Z direction is the vertical direction or the vertical direction, and the X, Y, and Z directions are orthogonal to each other. are doing. FIG. 1 shows a front view of a flat collective housing 1 . A foundation pile 3 is installed on the ground 27 , a foundation beam 4 is installed on the pile head 3A of the foundation pile 3 , and the superstructure 5 of the building is supported by the foundation beam 4 . The foundation piles 3 and the foundation beams 4 are collectively referred to as a foundation structure 2 . 2 is a plan view of the foundation beam 4 viewed from line AA in FIG. 1, FIG. 3 is a perspective view of the foundation structure 2, FIG. 4 is an exploded perspective view of the foundation structure 2, and FIG. Fig. 6 is a cross-sectional view along the line -B, Fig. 6 is a cross-sectional view along the CC line in Fig. 2, and Fig. 7 is a top view of the outer peripheral beam 6 and the footing 9 (enlarged view of part D in Fig. 2). showing. In addition, the hatched portion in FIG. 2 indicates the cast-in-place beam 6B or the cast-in-place portion 7B.

The plate-like collective housing 1 is a plate-like building having a plurality of spans in the girder direction X and one span in the beam-to-beam direction Y. As shown in FIG. The foundation beams 4 have a plurality of outer beams 6 arranged along the outer periphery of the building and at least one inner beam 7 provided inside the outer peripheral beams 6 . The outer beams 6 and the inner beams 7 form an underground space 8 together with the floor slab 24 of the ground floor, and the underground space 8 is divided by the inner beams 7 into a plurality of compartments 8A.

The outer peripheral beam 6 is basically precast, but as will be described later, at least one outer peripheral beam 6, in this embodiment only one outer peripheral beam 6, is a cast-in-place beam 6B, and the rest are precast. ing. The outer peripheral beam 6 in the girder direction X is a precast beam (PCa beam) 6A divided by span, and the outer peripheral beam 6 in the inter-beam direction Y is equally divided into three PCa portions 6C. The outer peripheral beams 6 in the beam-to-beam direction Y are structurally one beam, and the PCa portions 6C are joined with mortar.

The internal beams 7 are provided for each span and connect the peripheral beams 6 facing each other in the Y direction. Each internal beam 7 is equally divided into three parts: two precast parts (PCa parts) 7A and one cast-in-place part 7B. The internal beam 7 is structurally one beam, and the PCa portions 7A are joined together by mortar. The PCa portion 7A and the cast-in-place portion 7B are joined with cast-in-place concrete. In this embodiment, the cast-in-place part 7B is provided at the end of the internal beam 7 in the Y direction, but the cast-in-place part 7B may be provided at the central part of the internal beam 7 in the Y direction. The on-site placement portion 7B may be provided anywhere on the internal beam 7, and its Y-direction position and Y-direction length are not limited. The number of divisions of the outer beams 6 and the internal beams 7 in the inter-beam direction Y is not limited to three, and may be two or four or more. Since the PCa beam 6A and the PCa portions 6C and 7A are installed by a lifting machine, it is preferable to determine the number of divisions in consideration of the performance of the lifting machine. In order to secure the range of the PCa portion 7A as much as possible, it is preferable that the length of the cast-in-place portion 7B in the Y direction is approximately 1/3 or less of the length of the internal beam 7 in the Y direction.

A footing 9 is provided at the intersection of the outer beam 6 and the internal beam 7 . The footing 9 is a roughly rectangular parallelepiped reinforced concrete structure that is constructed on site. The footing 9 has a shape in which the upper part is cut on the outer wall side of the building. A foundation pile 3 is provided under the footing 9, and a column 10 is provided above the footing 9. - 特許庁The foundation pile 3 is a steel pipe pile, and the pile head 3A is provided with a plurality of pile head reinforcing bars 11 . The pile head reinforcement 11 is provided in the circumferential direction by welding or the like on the side surface of the foundation pile 3 near the pile head 3A, and extends upward in the vertical direction Z. As shown in FIG. The pile head 3A of the foundation pile 3 and the pile head reinforcement 11 are covered with a footing 9. Considering the workability of the foundation structure 2, the lower end levels of the outer peripheral beam 6 and the inner beam 7 are the same. The lower end of footing 9 is below the lower ends of outer beam 6 and inner beam 7 . That is, during construction, the ground 27 is excavated deeper than the surroundings only in the range of the footing 9 .

The outer peripheral beam 6 has projecting portions 12 projecting on both sides in the width direction (Y direction) at its lower portion. Since the pile head reinforcing bars 11, the reinforcing bars 14 of the outer beam 6, the reinforcing bars 15 of the inner beams 7, and the like concentrate on the footing 9, it may be difficult to fit the reinforcing bars. In particular, the reinforcing bars 14 and 15 provided in the X and Y directions and the pile head reinforcing bar 11 provided on the circumference are likely to interfere with each other. As shown in FIGS. 4 to 7, at least part of the bottom reinforcements 14A of the outer beam 6, in this embodiment, the bottom reinforcements 14A on both sides in the Y direction are provided on the protruding portion 12, and the lower ends provided on the protruding portion 12 The reinforcement 14A passes through the outside of the pile head reinforcement 11 in the width direction (Y direction). As a result, a space for arranging the reinforcing bars is increased, and the fitting of the reinforcing bars is improved.

FIG. 8 is a side view of the inner beam 7 seen from line EE in FIG. Various through holes are provided in the internal beam 7 . Although the through holes are circular, they may be rectangular or other shapes. Four first through holes 16 through which drain pipes 23 pass are provided in the field placing portion 7B (one drain pipe 23 is shown as an example in FIG. 2). Three of the first through holes 16 are for the passage of drainage pipes for discharging waste water generated in bathrooms, toilets, kitchens, washrooms, and the like. The drain pipe 23 is normally connected to a public sewage pipe that is buried underground outside the plate-like housing complex 1 . For this reason, the wastewater generated in each dwelling unit is concentrated in one or several drainage pipes 23 in the housing complex, and is routed to the underground space 8 partitioned by the outer beam 6 and the internal beam 7, and is routed from the underground space 8 to the underground space 8. It is discharged to the outside of the flat collective housing 1 through the outer peripheral beams 6 . Another first through-hole 16 is for passing a drainage pipe for draining rainwater (hereinafter referred to as a drain pipe to distinguish it from the above-described drain pipe). In this embodiment, the drain line is also connected to the public sewer like other drain lines. A ventilation port 17 and a communication pipe 18 are further provided in the field placing portion 7B. The vents 17 are provided so as to allow air to communicate with each section 8A of the underground space 8 partitioned by the internal beams 7 in order to ensure the safety of people who enter the underground space 8 . A communication pipe 18 is provided at the bottom of the internal beam 7 to disperse water when a flood occurs in one section 8A of the underground space 8. As shown in FIG. The central PCa portion 7A is provided with a passage port 19 for allowing a person to move between the compartments 8A, and a common through hole 20 for water supply pipes and gas pipes. The PCa portion 7A at the end is provided with a vent 17, a communicating pipe 18, a through hole 21 for a strong electric system cable, and a through hole 22 for a weak electric system cable.

The drainage pipe 23 extends in a substantially vertical direction at a portion penetrating between the floors, and has a predetermined downward slope so that the drainage flows within the floor by gravity. The descending slope is set to a relatively gentle slope of, for example, about 1/100 to 3/100 so that dirt and the like can easily flow along with the water. In the underground space 8 as well, the routing route of the drainage pipe 23 is planned with this downslope as a guideline. However, if all the internal beams 7 are made of PCa, there is a possibility that a process mismatch will occur. FIG. 9 shows the main design process and construction process of collective housing when all the internal beams 7 are made of PCa. When the design starts, first the rough layout of each dwelling unit is decided, and then the structural design and equipment planning are carried out. The route of the drain pipe 23 is determined by the facility plan, but for that purpose, the layout of the toilet, kitchen, etc. must be determined. Therefore, the route of the drainage pipe 23 may not be determined until the latter half or the final stage of the facility planning. On the other hand, construction can be started as soon as the design is completed and procedures such as building confirmation are completed. After the start of construction, the foundation piles 3 are constructed first, and then the foundation beams 4 are constructed. PCa foundation beams are designed and manufactured in advance according to the timing of installation. The design of PCa foundation beams requires through-hole planning, ie information about the location, shape and size of the through-holes. However, since the design of the PCa foundation beams is carried out considerably earlier than the start of construction, there is a possibility that the plans for the through holes have not been finalized at that time. That is, there is a possibility that a mismatch in the process will occur. If a mismatch occurs, there is a possibility that the construction schedule will be seriously affected, such as delays in the construction of PCa foundation beams. In order to avoid this, it is necessary to plan the routing of the drainage pipe 23 in accordance with the predetermined position of the through hole. However, as described above, the drainage pipe 23 is severely restricted in terms of downward slope, which may have a significant impact on the facility planning, such as the impossibility of realizing a rational routing route. The above problems are peculiar to PCa foundation beams, and such problems basically do not occur in field-cast foundation beams, as long as the through-hole plan is fixed by the time of construction.

In this embodiment, at least the first through hole 16 through which the drainage pipe 23 passes is provided only in the field placing portion 7B. As described above, the on-site casting section 7B does not need to determine the plan for the through holes at an early stage, so mismatches in the process are less likely to occur. On the other hand, since the through-holes through which pipes other than the drainage pipe 23, cables, etc. pass through have a high degree of freedom in routing, even if the positions of the through-holes are determined in advance, there is no major limitation in routing. For example, since water supply pipes for tap water, fire water, etc. are usually pressurized, there are no major restrictions on the slope, and even if there is a mixture of downward slopes and upward slopes, it will not be a big problem. Cables have no gradient restrictions, so they have little impact on routing routes. Furthermore, such a problem does not occur in the first place with respect to the through holes (ventilation port 17, communication pipe 18, and access port 19) through which pipes and cables do not pass.

At least one first through-hole 16 through which the drain pipe 23 penetrates should be provided, and the number is not limited. However, in this embodiment, a plurality of first through holes 16 are provided in order to ensure flexibility in equipment planning, and at least some of the first through holes 16 have different diameters, and provided at different heights. Moreover, it is preferable that the through-holes provided in the PCa portion 7A be concentrated as much as possible. For example, in this embodiment, the through hole 20 is shared by the water supply pipe, the fire extinguishing pipe, and the gas pipe. As a result, the number of through-holes in the PCa portion 7A can be reduced, simplifying the design of the PCa portion 7A.

As described above, the outer peripheral beam 6 in the girder direction X consists of a plurality of precast beams 6A and one cast-in-place beam 6B. The cast-in-place beam 6B is provided only at a portion through which the drain pipe 23 penetrates. In this embodiment, a through-hole (hereinafter referred to as a second through-hole 25) for drawing out the drain pipe 23 to the outside is provided only in one of the on-site placement beams 6B. Therefore, among the outer peripheral beams 6 in the girder direction X, only one is the cast-in-place beam 6B, and the rest are all PCa beams 6A. Depending on how the drainage pipe 23 is routed, it is possible to provide a plurality of cast-in-place beams 6B.

Thus, in this embodiment, only the portion of the internal beam 7 where the first through-hole 16 through which the drain pipe 23 passes is provided is the on-site placement portion 7B, and the rest is the PCa portion 7A. In addition, only the portion of the external beam 6 where the second through hole 25 through which the drain pipe 23 penetrates is provided is the cast-in-place beam 6B, and the rest is the PCa beam 6A or the PCa portion 6C. For example, in a plate-like collective housing 1 with 6 spans in the girder direction X and 1 span in the beam direction Y, if the beams in the beam direction Y are divided into 3, the outer beam 6 consists of 17 PCa blocks and 1 cast-in-place. The internal beam 7 consists of 10 PCa blocks and 5 cast-in-place blocks. Therefore, there are a total of 27 PCa blocks and a total of 6 cast-in-place blocks. In other words, about 80% of the entire building can be made of PCa, so it is possible to shorten the construction period and ensure the quality of the foundation structure.

FIG. 10 is a view similar to FIG. 5 showing another embodiment of the invention. In this embodiment, the lower end levels of the outer peripheral beam 6 and the inner beam 7 are shifted in the vertical direction Z so that the respective lower muscle installation regions 61 and 71 do not overlap. More specifically, the lower end level of the internal beam 7 and the upper end level of the projecting portion 12 of the outer peripheral beam 6 are aligned. As a result, there is more room in the space for arranging the reinforcing bars, and the fitting of the reinforcing bars is further improved.

1 Plate-like housing complex 2 Foundation structure 3 Foundation pile 6 Peripheral beam 6A Precast beam (PCa beam)
6B Field cast beam 6C Precast part (PCa part)
7 Internal beam 7A Precast part (PCa part)
7B Field placing part 9 Footing 11 Pile head reinforcing bar 12 Overhang part 16 First through hole 25 Second through hole

Claims (10)

A plurality of perimeter beams arranged along the perimeter of the building and a plurality of interior beams provided inside the plurality of perimeter beams, the perimeter having one long side and the other long side and a pair of short sides,
Each of the plurality of internal beams has , along the length of the internal beam, a precast portion adjacent to the one long side , a central precast portion, and a cast-in-place portion adjacent to the other long side. divided into three
A basic structure of a plate-like housing complex, wherein at least one first through- hole through which a drainage pipe passes is provided only in said cast-in-place portion, and a access port is provided only in said central precast portion . 2. Foundation structure according to claim 1, wherein the cast-in-place portion is less than or equal to 1/3 the length of the internal beam. 3. The at least one first through-hole is a plurality of first through-holes, and the plurality of first through-holes are provided at different heights of the cast-in-place portion. Substructure as described in . 4. The substructure according to claim 3, wherein diameters of said plurality of first through holes are different from each other. 5. The precast portion according to any one of claims 1 to 4, wherein at least one of a through hole for electric wiring, a through hole for gas piping, a through hole for water supply piping, a vent, and a communicating pipe is provided in the precast portion. foundation structure. The plurality of peripheral beams have precast beams, cast-in-place beams, and at least one second through hole through which the drainage pipe passes, and the at least one second through hole is formed in the plurality of 6. Foundation structure according to any one of claims 1 to 5, provided only on the cast-in-place beams of the perimeter beams . A foundation pile provided under the intersection of the outer peripheral beam and the internal beam, and a pile head reinforcing bar provided at the pile head of the foundation pile and extending upward from the foundation pile,
The outer peripheral beam has an overhang portion projecting on both sides in the width direction at its lower portion, and at least a part of the lower end reinforcement of the outer peripheral beam is attached to the overhang portion so as to pass through the outside of the pile head reinforcement in the width direction. 7. A substructure according to any one of claims 1 to 6, provided. 8. The foundation structure according to any one of claims 1 to 7, wherein lower end levels of said peripheral beams and said internal beams are coincident. 8. The foundation structure according to any one of claims 1 to 7, wherein the lower end levels of said peripheral beams and said inner beams are vertically offset so that their respective lower reinforcement installation areas do not overlap. constructing a plurality of outer beams forming an outer circumference, and constructing a plurality of inner beams inside the plurality of outer beams;
The outer peripheral portion consists of one long side, the other long side and a pair of short sides,
Each of the plurality of internal beams has , along the length of the internal beam, a precast portion adjacent to the one long side , a central precast portion, and a cast-in-place portion adjacent to the other long side. divided into three
A method of constructing a foundation structure for a plate-like housing complex, wherein at least one first through- hole through which a drainage pipe penetrates is provided only in the cast-in-place portion, and a access port is provided only in the central precast portion .

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