JP4445341B2 - Building foundation and its construction method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a building foundation structure, and relates to a building foundation structure having a structure in which a pile foundation portion and a solid foundation portion are integrated by forming a joint portion and a construction method thereof.

  In general, if the surface ground does not have sufficient bearing strength to support the load of the building, use a solid foundation such as a solid foundation or cloth foundation and use the load bearing capacity of the surface ground. Rather, it is necessary to support the load on a strong ground located below the surface ground. In such a case, a pile foundation having a pile head connected to the support pile body standing upright from the support layer and the upper part of the support pile body has been conventionally employed, with the solid ground as a support layer (for example, Non-patent document 1). According to the pile foundation, since the load of the building is mainly supported by the support pile body and the support layer, the load of the building can be supported regardless of the soft ground located on the surface layer. Are better.

  Since the conventional pile foundation employs a structure in which almost all the load of the building is supported by the support pile body and the support layer as described above, the load on the support pile body is very large. Therefore, there is a problem that when a vibration is generated due to an earthquake or the like and a force in the horizontal direction and the vertical direction is generated in the ground, the support pile body cannot support the load and the support pile body is easily damaged. However, as above-mentioned, when a pile foundation structure is employ | adopted, it is common that there is no support yield strength which supports this load on the surface layer ground with respect to the load of the building constructed. Therefore, the pile foundation and the direct foundation were used together, and the load bearing capacity of the building on the foundation and the surface ground in contact with the foundation could not be used together with the bearing capacity of the supporting pile body.

Moreover, there is another problem described below due to the concentrated load on the support pile.
Generally, the building load is biased with respect to the horizontal plane. For this reason, the load which each support pile body supports is not uniform, and a balance may be bad. If this is left unattended, the building will be stable if the load on the pile support increases due to the above load imbalance and the support pile breaks due to various subsequent factors such as changes in the ground environment and surrounding environment, or the occurrence of external forces such as earthquake vibration. It is very dangerous because it will not be supported by.

  Furthermore, the surface layer ground that is so soft that the bearing strength is not exhibited against the load of the building tends to cause deformation of the ground shape due to external force, and thus has the following another problem. That is, there is a problem that cavities and voids are likely to be formed in the ground around the pile foundation due to the occurrence of vibration due to an earthquake or the like or the liquefaction phenomenon of the ground. The formation of the cavities and voids impairs the stability of the support pile, and as a result, the stability of the building is impaired, which is very dangerous.

The Architectural Institute of Japan, “Basic Design Guidelines for Architectural Foundations”, 1st Edition, 8th Edition, The Architectural Institute of Japan, July 25, 1996, p. 197-214

This invention is made | formed in view of the problem of the said conventional pile foundation. That is, according to the present invention, by using a pile foundation and a solid foundation in combination, the support load of the support pile body is reduced, and the balance of the load load of each support pile body is well adjusted. An object of the present invention is to provide a foundation structure capable of stably supporting a building by preventing the formation of cavities and voids in the ground.

Another object of the present invention is to provide a construction method for constructing the foundation structure of the present invention, and more specifically, it is possible to adjust the load bias of the building applied to each supporting pile body as the building is constructed. In addition, to provide a foundation construction method that enables the combined use of pile foundations and solid foundations by appropriately compressing the surface ground around the foundations, thereby reducing the load bearing load of the supporting pile bodies. It is intended.

The present invention
(1) it has a pile foundation and a solid base portion and a bearing pile body and the pile head, in contact between the pile head and the solid foundation, a polystyrene resin foam, polyethylene resin foam, and A strained material selected from any of polypropylene resin foams and combinations thereof is installed , and includes a joint portion having the strained material, and excludes a surface in contact with the strained material in the ground wherein is embedded foam resin plate is in contact with the solid foundation, compressive creep ratio of the foamed resin board and the strain member is distorted material: foamed resin Release = 2: 1 to 200: 1 der Rukoto Characteristic building foundations,
(2) The strained material is a foamed resin block formed by in-mold foaming in which bead-like foam particles are filled and heated to fuse the foam particles together. Foundation structure for buildings,
Is a summary.

In the present invention, a strained material is provided between the pile head and the solid foundation, and as the building is constructed above the foundation structure, the strained material is distorted by the load of the building, and the surroundings are accordingly The effect of compressing the surface layer of is also demonstrated. The compressed surface layer ground has a high ground density, and load bearing strength is generated in the surface layer ground. As a result, a load supporting force is generated in the solid foundation part in contact with the surface ground, and as a result, the pile foundation part and the solid foundation part can be used in combination.
When a desired amount of strain is generated in the strained material, a pile foundation portion and a solid foundation portion are integrated by forming a rigid joint including the strained material, thereby completing the foundation structure of the present invention. Is done.
Therefore, even on the surface layer ground that does not have the load bearing strength to support the building, it is possible to stably support the building without applying excessive load to the support pile by constructing the foundation structure of the present invention. it can.

That is, in the foundation structure of the present invention, not only the load of the building constructed above is supported by the support pile body and the support layer, but also the load support force of the solid foundation part and the surface layer ground below it is supported together. can do. As a result, compared with the conventional pile foundation, the load support burden of the support pile body is remarkably reduced, and the building can be supported more stably.
Even if earthquake vibration or traffic vibration occurs and horizontal and vertical forces are applied to the support pile body, the foundation structure of the present invention is provided with a solid foundation and a pile foundation. As a result, the load received by the support pile is reduced. Therefore, according to the present invention, even if vibration occurs due to an earthquake or the like, the support pile body is prevented from being damaged, and the building can be favorably supported.

  As described above, since the strained material is used in the present invention, the bias of the load of the building with respect to the support pile body can be adjusted by the strained material. That is, the strain amount of one strained material and the surface layer ground located below the heavy load structural portion of the building is large, and the other strain material and the surface layer ground located below the relatively lightly loaded structural portion. The amount of distortion is reduced. On the other hand, the compressive strength of each strained material is appropriately determined in advance, and the balance of the load deviation of the building can be adjusted by adjusting the difference in the amount of strain, and as a result, located below the strained material. It is possible to eliminate the load caused by the load weight of the building against the support pile.

  Furthermore, as described above, as the strain material is distorted, the surrounding surface ground is compressed, resulting in a higher ground density than before construction, resulting in vibration due to earthquakes, etc., or liquefaction of the ground. In addition, it is possible to prevent or reduce the generation of voids in the surface ground around the foundation.

In particular, the present invention, since the allowed to place in contact the foamed resin board in a solid foundation, seismic vibration by foam resin plate, traffic vibration, vibration such as mechanical vibration is absorbed. As a result, the influence of vibration received by the foundation structure is reduced, and the magnitude of vibration transmitted directly to the building via the foundation is reduced, thereby preventing or reducing the shaking of the building.

And if it is the construction method of this invention, when constructing a building by installing a distortion material between a support pile body and a solid foundation part, a distortion material will be gradually distorted by the load of this building. It is possible to compress the surface ground located below the foundation as the strain material is distorted. Therefore, even when there is a bias in the load of the building, the bias is adjusted by the strain amount of each strained material, so the load on the support pile body can be reduced. Moreover, even if it does not perform special operations, such as consolidation, a surface layer ground can be compressed easily and moderately and support strength can be provided to this surface layer ground. As a result, even in the surface ground where the bearing strength of the building load is not sufficient, the foundation structure of the present invention including the pile foundation part and the solid foundation part can be constructed, and further, a rigid joint including a distortion material. By forming the pile foundation part and the solid foundation part can be easily integrated.

  The best mode for carrying out the present invention will be described below with reference to the drawings illustrating the present invention.

FIG. 1 is an explanatory view showing compression of a strained material in an embodiment of the present invention. In order to construct the foundation structure of the present invention, first, as shown in FIG. 1 (1A), a pile foundation portion including a supporting pile body 3 and a pile head 2 is constructed, and a strain of thickness P is formed on the upper surface of the pile head 2 The material 1a is installed, and then a solid foundation 4a which is a direct foundation is constructed. Next, a building 7 is constructed above them. During the construction of the building 7, the strained material 1a is gradually distorted to become a strained material 1b having a thickness Q as shown in FIG. 1 (1B). When the strained material 1b is compressed in the longitudinal direction, the compression creep limit is exceeded and the rigidity is exhibited. As a result, a joint made of the strained material 1b is formed, and the pile foundation portion composed of the pile head 2 and the support pile body 3 is formed. And the solid foundation 4a are joined and integrated through the joining portion to complete the foundation structure of the present invention.
In this specification, GL means the ground level.

  FIG. 2 is a schematic longitudinal sectional view showing an embodiment of the basic structure of the present invention. The foundation structure shown in FIG. 2 can be constructed in the same manner as the foundation structure shown in FIG. 1 except that the foamed resin board 8 is directly laid in contact with the solid foundation 4a that is the foundation portion.

Below, the construction method of the basic structure of this invention is demonstrated mainly using FIG.
First, the support pile body 3 is placed in a predetermined position so that the tip thereof is embedded in the support layer 6, and then a part of the surface layer ground 5 is discharged, and the pile including the exposed upper portion of the support pile body 3 is included. Head 2 is formed. The above-mentioned placement of the support pile body 3 and formation of the pile head 2 can be performed by a method similar to a conventionally known method for constructing a pile foundation.

Next, the strain material 1 a is installed on the upper surface of the pile head 2. The strained material 1a may be simply placed on the upper surface of the pile head 2, or the upper surface of the pile head 2 and the lower surface of the strained material 1a may be bonded using an adhesive or an adhesive material. Then, after the strained material 1a is installed, the periphery of the side surface of the strained material 1a is backfilled to the height of the upper surface of the strained material 1a, or the foamed resin board 8 is raised to the height of the upper surface of the strained material 1a as shown in FIG. Arrange the construction surface by laying.
In order to form a joint between the pile head 2 and the solid foundation 4a which is a direct foundation in a later process, in the step of installing the strained material 1, the strained material 1 and the pile head 2 are previously shown in FIG. A concrete filling space 10 can be provided around the side surface of the steel sheet. Further, as shown in FIG. 4 , reinforcing bars 14 may be provided on the pile head 2 and the solid foundation 4 in addition to the concrete filling space 10.

It is important that the strained material in the present invention is provided between the pile head and the solid foundation, and is distorted by the load of the building 7 constructed above the solid foundation.

In particular, the present invention further to provide a foamed resin board 8 in direct contact with the base portion 4 can be laid for example a foamed resin plate 8 as shown in FIG. 2 in a predetermined position. The foamed resin board 8 can be formed into a foamed resin board 8 by combining a plurality of foamed resin blocks having arbitrary dimensions and shapes. In order to form the foamed resin board 8 by the plurality of foamed resin blocks, the foamed resin board 8 is formed by simply combining or stacking the blocks in the hole formed for embedding the foamed resin board 8. Alternatively, the foamed resin board 8 is formed by bonding the foamed resin blocks with an arbitrary adhesive or adhesive tape, or joining the foamed resin blocks with a fastener such as a bolt or a fastening metal fitting. May be.
The arrangement of the foamed resin board 8 is not limited to the arrangement position disclosed in FIG. For example, the foamed resin board 8 may be laid so that a part or the whole of the solid foundation 4a and the surface layer ground 5 is isolated, and further, a part or all of the strained material 1 and the pile head 2 and the surface layer ground 5. May be laid so as to be isolated from each other. Furthermore, when the foundation structure of the present invention is adopted as the foundation of a building having a basement, it is preferable that the foamed resin board is also laid between the side surface of the basement and the ground.

  In the present invention, the solid foundation 4a can be constructed by using a solid foundation construction method known as a direct foundation. However, in the construction method of the present invention, after the solid foundation 4a is constructed, the strained material 1a is distorted as the building 7 is constructed, and the position of the solid foundation 4a located above the strained material 1a is also lowered by the amount of the strain. Therefore, it is necessary to provide the solid foundation 4a at a position higher than the height at which the solid foundation should be finally positioned by the amount of distortion (PQ) expected in the strained material 1a.

  At the time of constructing the support pile body 3, the pile head 2, the strained material 1a, and the solid foundation 4a, the strained material 1a is not distorted to the extent that a joint is formed. Then, the building 7 is constructed above the solid foundation 4a. As the building 7 is constructed, the distortion material 1a is subjected to the load of the building 7 and is distorted. At the same time, the surface ground 5 located below the solid foundation 4a where the strained material 1a is not disposed is also compressed.

  In particular, when the building 7 is constructed by providing the foamed resin board 8 in the present invention, when the foamed resin board 8 is compressed as the strained material 1a is distorted, both the foamed resin board 8 and the surface layer ground 5 located below the foamed resin board 8 are provided. In some cases, only the surface ground 5 is compressed. Whether one or both of the foamed resin board 8 and the surface layer ground 5 due to the load applied from above is compressed depends on the relationship between the compressive strength of the foamed resin board 8 and the support strength of the surface layer ground 5. However, in any case, the soft layer around the foundation structure is compressed, and load bearing strength is generated there.

Next, during the construction of the building 7, the strain amount of the strained material 1 b is measured. The strain amount of the strained material used in the present specification means a difference in height between the strained material before and after the load from above is applied.
As a measuring method of the strain amount of the strained material, the thickness Q of the strained material 1b is directly measured, and the strain amount (PQ) can be calculated from the dimension P when the strained material 1a is installed and the above Q. . As another measuring method, the amount of settlement of the building 7 or the solid foundation 4a can be measured based on the ground level and converted into the amount of distortion.

  As described above, the strain amount (PQ) of the strained material 1b is measured, and after confirming that the strain amount is distorted by a desired amount, preferably 1 cm or more and 20 cm or less, a joint portion is formed. At this time, the strain amount may be different depending on each strain material, or may be the same. However, if the difference in the amount of strain of each strained material is too large, the horizontality of the building may be hindered. Therefore, if the load on the building 7 is largely biased with respect to the horizontal plane, etc. It is desirable to appropriately determine the compressive strength in accordance with each supporting load and adjust the strain amount of each strained material. Thus, by adjusting the bias of the load of the building with the strained material, the load due to the unbalanced load of the building can be reduced with respect to the support pile positioned below the strained material. Further, the strain amount of the strained material may be adjusted to a desired amount by installing a hydraulic jack at the time of installing the strained material and operating the hydraulic jack.

The joint part in this invention can use as a joint part the distortion material which was compressed by the load of the building and produced rigidity. For example, it is known that a foamed resin body is distorted in the compression direction when compressed, and becomes very hard when the compression creep limit is exceeded. By using this property, if a foamed resin body is used for the strain material, it is possible to distort the strain material made of the foamed resin body to a hardness equivalent to concrete by applying a building load from above. This hard and distorted strain material can be used as a joint.
As another method for forming the joint, there is a method in which the strained material 1 is distorted by the load of the building, and then the concrete filling space 10 is filled with concrete, and the strained material is solidified from the surroundings to form the joint (see FIG. 3 ). Furthermore, if reinforcing bars 14 are provided on the pile head 2 and the direct foundation 4 in advance, when the concrete filling space 10 is filled with concrete, the reinforcing bars 14 form a framework in the concrete and form a more robust joint. (See FIG. 4 ).

If it is the construction method of the foundation structure of the present invention described above, it is only necessary to construct the building by installing the distortion material at an arbitrary position between the pile head and the solid foundation portion, and the distortion material by the load of the building. Can be gradually distorted, and the surrounding surface ground (or foamed resin board) can be compressed by the amount of strain of the strain material. Then, after obtaining an appropriate amount of strain, a joint having rigidity including a strained material can be formed, and the pile foundation and the solid foundation can be easily integrated. This completes the foundation structure of the present invention that can favorably support the load of the building between the pile foundation and the solid foundation without requiring a particularly complicated construction work.

After completing the basic structure of the present invention, the rest of the building 7 can be constructed. At this time, since the strained material 1b constituting the joint exceeds the compression creep limit, the strained material 1 is not further distorted. Further, the joint portion including the strained material shown in FIG. 3 or FIG. 4 is solidified with concrete, and further, the strained material is not distorted.

  The foundation structure constructed by the construction method of the present invention described above can also be adopted for the foundation of a building having a basement part. In this case, the foundation structure is constructed under the basement space. That's fine. In particular, as shown in FIG. 2, when the foamed resin board 8 is provided in direct contact with the base portion 4 in the present invention, the foamed resin board 8 can be further disposed in contact with the outer surface of the basement. According to this, since not only the foundation structure but also the part of the building buried in the ground is isolated from the ground by the foamed resin board 8, earthquake vibration, traffic vibration, mechanical vibration, etc. are transmitted to the building 7. This is preferable because it becomes difficult and the shaking of the building 7 can be reduced.

In addition, the foundation structure for a building of the present invention can be constructed as a foundation structure of a new building by the above construction method, and can also be applied to an existing building where a pile foundation is adopted. . When using the foundation structure of the present invention for an existing building, the structural portion such as the floor and slab at a predetermined position of the building is removed to expose the upper end of the pile, the pile head in the present invention, the distortion material, And the top of the pile is cut to secure the installation space for the solid foundation. Then, the pile head, the strained material, and the solid foundation are sequentially formed, and at the same time, a hydraulic jack is installed at the position where the strained material is installed, and the jack is removed by gradually distorting the strained material by operating the jack. Next, a strained material distorted to a desired amount is used as a joint, as in the above-described joint formation method, or a joint is formed by filling concrete around the strained material, and an existing support pile body and The basic structure of the present invention can be completed by integrating the newly provided direct foundation.

Next, the basic structure of the present invention will be described in detail for each configuration.
The support pile body in the present invention may be of any type as long as it stands vertically from the support layer and can transmit the load of the building to the support layer. Specifically, there are driven piles that are driven into the ground using existing pile bodies, embedded piles that are provided with holes in the ground and embedded in existing pile bodies, or cast-in-place concrete piles such as all-casing piles or earth drill method piles, etc. However, it is not limited to the above.

  And the pile head is provided in the upper part of the said support pile body. If the pile head in this invention can receive the load of a building from upper direction and can transmit this to a support pile body, it will not receive a restriction | limiting in particular in the magnitude | size and a raw material. That is, the support pile body and the pile head can be appropriately selected and used as long as they constitute a conventionally known pile foundation.

The strained material used in the present invention needs to be formed of a material or a shape that exhibits a certain amount of strain due to a load transmitted from above. Specifically, it can be formed using a foamed resin body. The shape of the strained material formed by the foamed resin body is not particularly limited, but since the strained material is installed between the pile head and the solid foundation, it is desirable that the installation stability is good between the two. From this point, for example, a rectangular parallelepiped shape or a cylindrical shape is preferable.

As the foamed resin body used for the strained material, a polystyrene resin foam, a polyethylene resin foam, a polypropylene resin foam, and a combination thereof are preferable in terms of weight and strength. Polyurethane resin foams may deteriorate in durability when hydrolysis occurs in the ground. Polyvinyl chloride resin foams generate hydrochloric acid gas when burned, causing pollution problems. .

  The strained material formed from the foamed resin body has a desired shape by so-called in-mold foaming in which a bead-like foam particle is filled in a container formed in a desired shape and heated to fuse the foam particles together. It can be formed as a foamed resin block. Alternatively, a desired shape can be obtained by filling spherical foamed particles in a suitably shaped container and heating them to fuse the foamed particles together to form a suitably shaped foamed resin block and then processing it into the desired shape. It can be formed as a foamed resin block of the shape.

  The compression creep of the foamed resin body constituting the strained material is preferably 5% or more, more preferably 10% or more, and further preferably 15% or more. It is preferable that the compression creep is 5% or more because the compression creep can be gradually distorted by being compressed by the load of the building constructed above the foundation on which the strain material is installed. On the other hand, the upper limit of the compression creep is not particularly limited, but from the viewpoint of preventing the strained material from reaching the creep limit due to the weight of the foundation directly before building the building, the compression creep is 90%. % Or less, more preferably 80% or less, and even more preferably 70% or less.

The compression creep of the strained material can be measured according to JIS K 6767. Specifically, a test piece having a vertical dimension of about 50 mm, a horizontal dimension of about 50 mm, and a thickness of about 25 mm is prepared using a foamed resin body constituting a strained material, and the temperature is 20 ± 2 ° C. and the relative humidity is 65 ± 5%. When the thickness of the test piece when a load of ² g / cm ² is applied to the test piece in the standard state is T _0, and the thickness after 24 hours is Td when the load is left under the above load. Calculated by (T ₀ −T _d ) ÷ T ₀ × 100.

  The dimension of the strained material may be determined so as to obtain a desired strain amount, preferably a strain amount of 1 cm or more and 20 cm or less, during the construction of the building in consideration of the compression creep of the strain material and the building load. it can.

The compressive strength of the foamed resin body used for the strained material of the present invention is not particularly limited, and can be determined in consideration of the supporting force of the pile foundation and the load of the building. Compressive strength of the foamed resin is preferably 30 N / cm ² or more 100 N / cm ² or less.
In addition, the compressive strength of the said foamed resin body can be measured according to the measuring method of the short-term compressive strength shown by JISK7220. Specifically, a test piece having a vertical dimension of about 50 mm, a horizontal dimension of about 50 mm, and a thickness of about 50 mm is prepared, the test piece is compressed at a loading speed of 10 mm / min, and the compressive stress at 5% compression strain is measured. Thus, the compression strength in the present invention can be obtained.

  In the present invention, the foamed resin board used in direct contact with the foundation can be formed by combining a plurality of foamed resin blocks having arbitrary shapes and dimensions as described above. The foamed resin block can be molded by the same molding method using the same resin as the foamed resin body block that can be used for the strain material.

  The foamed resin board exhibits an effect of attenuating vibrations such as earthquake vibrations, traffic vibrations or mechanical vibrations transmitted from the ground, and prevents or reduces the transmission of these vibrations to the foundation structure or the building. Can do. Therefore, it is preferable to use the above-mentioned foamed resin board in the present invention because it can prevent the foundation structure from being damaged due to the occurrence of vibration and can reduce the body seismic intensity in the building.

  In laying the foamed resin board in the present invention, it is necessary that the compression creep value of the strained material is larger than the compression creep value of the foamed resin board. The preferable compression creep ratio of the two differs depending on the area ratio in which the strained material and the foamed resin board are in direct contact with the foundation, but the strained material: foamed resin board is required to be in the range of 2: 1 to 200: 1. . By securing the compression creep ratio within the above range, the strained material can be preferentially distorted when a load is applied to the strained material and the foamed resin board. On the other hand, whether or not the foamed resin board is compressed and distorted together with the strained material at this time depends on the relationship between the compression creep value of the foamed resin board and the load bearing strength of the surface layer ground located below the foamed resin board. That is, in the foamed resin board and the surface ground, the layer with weaker load resistance is compressed, which increases the density of the compressed layer, improves the load resistance compared to before compression, The load can be supported.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing explaining the embodiment of this invention, (1A) is the longitudinal cross-sectional schematic of the foundation structure before building construction, (1B) is a building constructed above the foundation structure shown by (1A). It is the longitudinal cross-sectional schematic of the basic structure of this invention by which distortion generate | occur | produced in the distortion material and the junction part was formed with this distortion material. It is a longitudinal section schematic diagram showing one embodiment of the basic structure of the present invention. It is a partial longitudinal section schematic diagram of the present invention. It is a partial longitudinal section schematic diagram of the present invention.

Explanation of symbols

1 Distorted material
DESCRIPTION OF SYMBOLS 1a Strained material before building construction 1b Strained material composing the joint 2 Pile head 3 Support pile body 4 Direct foundation 4a Solid foundation 5 Surface ground 6 Support layer 7 Building 8 Foamed resin board 10 Concrete filling space 14 Reinforcement 16 Concrete slab 17 Concrete plate P Thickness of strained material 1a Q Thickness of strained material 1b

Claims (2)

It has a pile foundation and a solid base portion and a bearing pile body and the pile head, in contact between the pile head and the solid foundation, a polystyrene resin foam, polyethylene resin foam, and a polypropylene resin The solid foundation provided with a strained material selected from any one of a foam and a combination thereof, including a joint having the strained material, and excluding a surface in contact with the strained material in the ground parts in contact with and foamed resin board is embedded, compression creep ratio of the foamed resin board and the strain member is distorted material: foamed resin Release = 2: 1 to 200: wherein the 1 der Rukoto Foundation structure for buildings. The building material according to claim 1, wherein the strain material is a foamed resin block formed by in-mold foaming in which bead-like foam particles are filled and heated to fuse the foam particles together. Foundation structure.

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