JP2008174936A - Foundation structure for measure against expandable ground and method of constructing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foundation structure for a measure against an expandable ground capable of constructing a foundation (base structure) for supporting a structure constructed on the expandable ground in a short period and a method of constructing the foundation structure. <P>SOLUTION: This foundation structure A for a measure against an expandable ground for supporting a structure constructed on the expandable ground G comprises: a pile part 1 having a top end part 1a projecting from the ground surface G3 of the expandable ground G and disposed in the expandable ground G; and a concrete foundation part 3 joined to the top end part 1a and supported on the pile part 1 and so disposed as to form a space S between itself and the ground surface G3 of the expandable ground G. A support member 4 for supporting the concrete foundation part 3 in an uncured state in which the strength of a deposited concrete does not reach predetermined strength is interposed in the space S. The support member 4 receives an expansion force from the ground surface G3 and is deformed when the expandable ground G expands and so swells as to fill the space S. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inflatable ground countermeasure foundation structure for supporting a structure to be built on an inflatable ground and a method for constructing the foundation structure.

  Conventionally, when constructing a structure on the ground (expandable ground) where a material having potential expansibility such as steelmaking slag is reclaimed, the foundation supporting the structure (concrete foundation part) is directly constructed on the ground. There is a possibility that the foundation is pushed up by the uplift (expansion) of the ground and deformed or displaced. For this reason, when constructing a structure on such expansive ground, a foundation is constructed by forming a space according to the predicted amount of ground expansion between the ground (ground surface). By absorbing the amount of expansion in this space, the foundation and thus the deformation and displacement of the structure are prevented.

Moreover, in this kind of foundation construction method, for example, a frozen ice layer having a thickness corresponding to the predicted amount of ground expansion as disclosed in Patent Document 1 is formed on the ground, and this frozen ice layer There is one that has been constructed by placing concrete on top. In this construction method, after placing a pile, a dam (form for frozen ice layer) is assembled on the ground so as to surround the foundation construction position, and a refrigeration pipe is installed in the dam. Next, water is stored in the weir, and the frozen ice layer is formed by freezing the water using a pipe and a refrigerator connected to the pipe. And, concrete is placed on a mold (foundation mold) formed on the frozen ice layer with the frozen ice layer as the bottom mold, until the concrete reaches a predetermined strength and the foundation is supported by the pile, This uncured foundation is supported by a frozen ice layer. When the cast concrete is hardened and the foundation is supported by the pile, the foundation formwork and the weir are disassembled and the frozen ice layer is thawed. And the space according to the expansion | swelling amount of the ground estimated between the foundation supported by the pile and the ground is formed by draining the melted water at any time and removing the piping.
Japanese Patent Laid-Open No. 10-280379

  However, in the foundation construction method described above, there are many facilities such as weirs, pipes, and refrigerators, and it is necessary to maintain the frozen ice layer so as not to melt until the foundation concrete exhibits a predetermined strength. For this reason, it becomes necessary to form a large frozen ice layer and maintain it for a long time, especially as the foundation construction area is vast, resulting in higher costs. In addition, since a lot of time is required for water freezing, thawing, drainage treatment, installation and removal of these facilities, there is a problem that the construction period is prolonged.

  On the other hand, sand is laid on the ground to form a sand layer with a thickness corresponding to the amount of expansion, and a foundation is constructed using this sand layer as a bottom mold. After the foundation concrete has hardened, the sand is removed with, for example, a water jet. However, in this case as well, it is necessary to remove the sand layer, so that it takes a lot of time to form the space.

  In view of the above circumstances, the present invention provides a foundation structure for inflatable ground countermeasures and a method for constructing the foundation structure capable of constructing a foundation (foundation structure) for supporting a structure to be built on the inflatable ground in a short period of time. For the purpose.

  In order to achieve the above object, the present invention provides the following means.

  The inflatable ground countermeasure foundation structure of the present invention is an inflatable ground countermeasure foundation structure for supporting a structure to be built on the inflatable ground, with an upper end protruding from the ground surface of the inflatable ground. Concrete that is disposed so as to form a space between the pile portion disposed in the expandable ground and the pile portion connected to the upper end portion and supported by the ground surface of the expandable ground. A support member is provided in the space, the support member supporting the uncured concrete foundation portion in which the placed concrete does not reach a predetermined strength, and is provided between the concrete foundation portion and the expansive ground. The support member is interposed, and is deformed by receiving an expansion force from the ground surface when the expandable ground expands and bulges to fill the space.

  The foundation structure construction method of the present invention is a foundation structure construction method for supporting a structure to be built on an inflatable ground, the upper end projecting from the ground surface of the inflatable ground, and After disposing the pile portion in the expansible ground, a support member is disposed on the ground surface, a bottom plate serving as a bottom mold is disposed on the support member to form a mold, and the mold is Concrete is placed, and the concrete foundation part supporting the structure together with the pile part is constructed in a state where a space is formed between the ground surface, and the support member is formed by expanding the inflatable ground. When the bulge expands to fill the space, it is deformed by receiving an expansion force from the ground surface.

  In the above invention, the uncured concrete foundation can be supported by the support member to form a space, and the inflatable ground expands after the concrete foundation is cured and supported by the pile. Since the expansion force acts and the support member is deformed, even if the support member is interposed in the space, that is, when the support member is left in the space, the expansion force is applied to the concrete foundation. It is possible to prevent deformation and displacement from occurring in the concrete foundation and thus the structure without acting. Thereby, it is not necessary to remove the support member for forming a space.

  In the inflatable ground countermeasure foundation structure of the present invention, the support member is preferably formed in a cylindrical shape or a box shape that buckles and deforms upon receiving the expansion force.

  In this invention, when the expansion force is applied, the expansion force can be reliably absorbed by the buckling deformation of the support member, and the deformation and displacement of the concrete foundation and the structure can be reliably prevented.

  Furthermore, in the foundation structure for expansive ground measures of this invention, it is more desirable for the said pile part to provide a frictional force reduction part in the part located in the expansible layer of the said expansible ground.

  In this invention, since it can suppress that a friction force arises in a pile part when an expansible ground expand | swells, a deformation | transformation and displacement of a concrete foundation part can be prevented more reliably with a support member.

  According to the inflatable ground countermeasure foundation structure and the foundation structure construction method of the present invention, it is not necessary to remove the support member for forming the space, so that the foundation structure can be constructed in a short time.

  Hereinafter, with reference to FIGS. 1 to 4, an inflatable ground countermeasure foundation structure and a construction method of the foundation structure according to an embodiment of the present invention will be described. The present embodiment relates to a foundation structure for supporting a structure to be built on an expansive ground in which a material having latent expansibility such as steelmaking slag is buried, and a method for constructing the foundation structure.

  As shown in FIG. 1, the foundation structure (foundation structure) A for inflatable ground according to this embodiment is provided by penetrating the inflatable layer G1 of the inflatable ground (ground) G and supporting it on a deep support layer G2. The pile 1 and the bottom plate 2 through which the upper end 1a of the pile 1 projecting upward from the ground surface G3 of the ground G penetrates, and is formed on the bottom plate 2 and is integrally connected to the upper end of the pile 1 and supported. Placed in the space S formed between the concrete foundation part 3 and the concrete foundation part 3 and the ground G (ground surface G3), the upper end is the lower surface of the concrete foundation part 3 (bottom plate 2), and the lower end is the ground G The side ground G is supported so that the side ground G does not enter the space S with respect to the support member 4 interposed in the space S in contact with the ground surface G3 and the concrete foundation 3. The earth retaining block 5 is provided.

  The pile portion 1 of the present embodiment is a steel pipe pile, and for example, grease is applied to the surface (outer peripheral surface) of the portion located in the expansible layer G1, and the resin sheet is formed using this grease as an adhesive. A friction force reducing portion (SL portion: slip layer portion) 1b formed by winding or applying a bitumen material is provided. That is, the pile portion 1 of the present embodiment is a friction force countermeasure pile (SL pile) capable of suppressing the frictional force that can be generated in the pile portion 1 with the expansion of the expandable layer G1 by the viscoelastic characteristics of the SL portion 1b. ing.

  The support member 4 of the present embodiment is formed in, for example, a tubular or box shape made of steel, that is, a hollow structure, and applies the load of the uncured concrete foundation portion 3 until the placed concrete reaches a predetermined strength. It is formed with such strength that it can be supported, that is, the thickness (height dimension) d1 of the space S can be maintained by preventing downward movement of the concrete foundation 3 during foundation construction. Further, the support member 4 is formed after the concrete exhibits a predetermined strength and the concrete foundation portion 3 is cured, that is, after the concrete foundation portion 3 is completely supported by the pile portion 1 by being integrated with the upper end portion 1a. When the ground G expands and bulges (swells) so as to fill the space S, it is formed with the strength to buckle and deform so that the concrete foundation portion 3 is not pushed up by this expansion force. Specifically, a one-hole can is used as the support member 4.

  Next, the construction method of the foundation structure A having the above configuration will be described, and the operation and effect of the foundation structure A of the present embodiment and the construction method of the foundation structure A will be described.

  When constructing the foundation structure A of the present embodiment, as shown in FIG. 2, the pile portion 1 that penetrates the expansible layer G1 and reaches the support layer G2 is formed in the ground region in which the concrete foundation portion 3 is constructed. To do. Next, the ground G is excavated to form the recess 6 so that a space S according to the expected amount of expansion of the ground G can be formed. At this time, the upper end portion 1a of the pile portion 1 is exposed in the recess 6 and protrudes upward from the bottom surface of the recess 6 (the ground surface G3 of the ground G).

  Next, as shown in FIG. 3, a plurality of support members 4 are installed on the ground G (ground surface G3) in an arrangement that can reliably support the load of the concrete foundation 3. Then, the bottom plate 2 as a bottom mold for placing the concrete of the concrete foundation portion 3 is placed on these support members 4 and supported by these support members 4. At this time, the bottom plate 2 is disposed so that the upper end portion 1a of the pile portion 1 penetrates the bottom plate 2 and protrudes upward with a predetermined dimension. Next, reinforcing bars are appropriately arranged, and as shown in FIG. 4, the side plate 7 that forms the side surface of the concrete base portion 3 is connected to the bottom plate 2, and a mold 8 composed of the bottom plate 2 and the side plate 7 is provided. Form. Concrete is placed when the mold 8 is formed in this manner.

  In the present embodiment, when the concrete is placed in the mold 8, the support member 4 is formed with a strength that can support the load of the uncured concrete foundation portion 3. Until the concrete foundation part 3 of the concrete exhibits a predetermined strength (until the concrete foundation part 3 is supported by the pile part 1), the uncured concrete foundation part 3 is reliably supported by the support member 4. . Then, when the concrete is hardened to a predetermined strength and the concrete foundation portion 3 is formed, the side plate 7 of the mold 8 is removed.

  Finally, as shown in FIG. 1, the earth retaining block 5 is installed on the side of the recess 6, and the space between the side surface of the recess 6 and the earth retaining block 5 is backfilled. Thereby, the construction of the foundation structure A is completed in a state where a space S corresponding to the expected expansion amount of the ground G is formed between the lower end of the foundation 3 and the ground surface G3 of the ground G. That is, in the present embodiment, the construction of the foundation structure A is completed in a state where the support member 4 for forming the space S is left in the space G without removing the support member 4.

  And when a structure is constructed | assembled on the concrete foundation part 3 of the foundation structure A constructed | assembled in this way, the space S according to the anticipated expansion | swelling amount is formed between the concrete foundation part 3 and the ground G. Therefore, even if the ground G having the potential expansion expands over a long period and the ground G (ground surface G3) rises (swells), the expansion amount of the ground G is absorbed by the space S, that is, the space gradually Only by being buried in the ground G where S is raised, deformation or displacement is not caused in the foundation structure A (concrete foundation portion 3) or the structure supported by the foundation structure A.

  On the other hand, in the foundation structure A of the present embodiment, the support member 4 is left in the space S in a state of being connected to the concrete foundation portion 3 and the ground G. For this reason, when the ground G expand | swells and rises, there exists a possibility that expansion force may act on the concrete base part 3 or a structure through the support member 4, and these may be pushed up. However, since the support member 4 of the present embodiment receives the expansion force from the ground surface G3 as the ground G rises and buckles and deforms, the deformation can reliably absorb the expansion force, and the concrete base portion. 3 and the deformation and displacement of the structure can be prevented. At this time, since the support member 4 is formed in a cylindrical or box-like hollow structure, an expansion force is applied from the ground G, and the buckling deformation can be surely performed.

  Moreover, in this embodiment, since the pile part 1 which supports a concrete foundation part 3 and a structure is equipped with the frictional force reduction part 1b, by the frictional force which generate | occur | produces in the pile part 1 with expansion | swelling of the ground G, It can prevent reliably that the pile part 1 moves so that it may be extracted from the ground G, and it can prevent reliably that a deformation | transformation and displacement arise in the concrete foundation part 3 and a structure.

  Therefore, according to the foundation structure A for inflatable ground countermeasures and the construction method of the foundation structure A of the present embodiment, the support member 4 can support the load of the uncured concrete foundation portion 3, and from the ground G By being formed with the strength to buckle and deform by the acting expansion force, it is possible to reliably form the space S for absorbing the bulge of the ground G and to eliminate the removal from the space S. Moreover, such a support member 4 can be installed by a simple method of arranging on the ground G when the foundation structure A is constructed. Thereby, it becomes possible to construct | assemble the basic structure A of this embodiment for supporting the structure constructed | assembled on the expansible ground G in a short period of time and low cost.

  As mentioned above, although embodiment of the foundation structure for inflatable ground measures and the construction method of this foundation structure concerning the present invention was described, the present invention is not limited to the above-mentioned one embodiment, and the range which does not deviate from the meaning It can be changed as appropriate. For example, in the present embodiment, the support member 4 is formed in a tubular or box shape of a steel hollow structure, and is formed so as to absorb the expansion force of the ground G by buckling deformation. The support member 4 according to the present invention is only required to be able to support the load of the uncured concrete base portion 3 and to be deformable so as to absorb the expansion force of the ground G. There is no need to limit the shape. In addition, for example, a support member is provided with a plurality of latching hinge mechanisms, and when supporting the uncured concrete foundation 3, the rotation of each hinge mechanism is locked, The hinges are unlocked at the stage where the concrete foundation part 3 is supported by the pile part 1 after being hardened, and each hinge is received so as to receive the expansion force when the ground G bulges and absorb the expansion force. You may comprise so that a mechanism may rotate and a support member may be changed. Therefore, the support member according to the present invention may be configured to absorb the expansion force by deformation other than buckling.

  Moreover, in this embodiment, the foundation structure A for expansive ground measures is comprised including the pile part 1, the baseplate 2, the concrete foundation part 3, the support member 4, and the earth retaining block 5. However, if the foundation structure A for inflatable ground measures of this invention is provided with the pile part 1, the concrete foundation part 3, and the support member 4, it can acquire the effect similar to this embodiment. .

It is a figure showing the foundation structure for inflatable ground measures concerning one embodiment of the present invention. It is a figure used in order to explain the construction method of the foundation structure for inflatable ground measures concerning one embodiment of the present invention, and is a figure showing the state where the pile part was arranged. It is a figure used in order to explain the construction method of the foundation structure for inflatable ground measures concerning one embodiment of the present invention, and is a figure showing the state where a support member was installed. It is a figure used in order to explain the construction method of the foundation structure for inflatable ground measures concerning one embodiment of the present invention, and is a figure showing the state where the bottom board was installed on the support member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pile part 1a Upper end part 1b Friction force reduction part 2 Bottom plate 3 Concrete foundation part 4 Supporting member 5 Earth retaining block 6 Recessed part 7 Side plate 8 Formwork A Foundation structure (Fundamental structure for expansive ground measures)
G Ground G1 Expandable layer G2 Support layer G3 Ground surface S Space

Claims (4)

A foundation structure for expansive ground measures for supporting a structure to be built on the expansive ground,
A pile portion disposed in the expansible ground by projecting an upper end portion from the ground surface of the expansible ground, connected to the upper end portion and supported by the pile portion, and a ground surface of the expansible ground With a concrete foundation arranged to form a space between,
A support member for supporting the uncured concrete foundation portion in which the placed concrete has not reached a predetermined strength is disposed in the space and interposed between the concrete foundation portion and the expansive ground. The inflatable ground countermeasure foundation structure, wherein the support member is deformed by receiving an expansion force from the ground surface when the expandable ground expands and fills the space. In the foundation structure for inflatable ground measures according to claim 1,
An inflatable ground countermeasure foundation structure, wherein the support member is formed in a cylindrical shape or a box shape that undergoes buckling deformation upon receiving the expansion force. In the foundation structure for inflatable ground measures according to claim 1 or claim 2,
The foundation structure for inflatable ground measures, wherein the pile part includes a frictional force reducing part in a portion located in the inflatable layer of the inflatable ground. A method for constructing a foundation structure for supporting a structure to be built on an expandable ground,
After a top end is protruded from the ground surface of the expandable ground and a pile portion is disposed in the expandable ground, a support member is disposed on the ground surface, and a bottom plate serving as a bottom mold frame on the support member In a state where a space is formed between the concrete foundation portion supporting the structure together with the pile portion and the ground surface. The construction method of a foundation structure, wherein the support member is deformed by receiving an expansion force from the ground surface when the expandable ground expands and fills the space.

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