JP4803438B2 - Existing foundation renovation structure and method - Google Patents

Description

  The present invention relates to a repair structure and a repair method for an existing foundation when an existing foundation structure and an existing pile are separated by an external force such as an earthquake.

Currently, there are many structures including a foundation having a structure in which a footing is joined to an upper end portion of a pile.
As for the joint structure between the pile and the footing, a joint structure in which the upper end of the main reinforcing bar of the pile is fixed in the footing or a whisker muscle that protrudes upward on the outer peripheral surface of the pile head of the steel pipe pile is welded. A joining method for fixing the upper end portion in the footing is common.
In recent years, a steel pipe extending in the direction of the pile axis is made to protrude upward on the pile head, and a fixed reinforcing bar material is protruded upward in this steel pipe to place the bar and concrete is placed and placed. There has been proposed a joining method in which a fixing reinforcing bar projecting from the upper end surface of a joined concrete part is fixed in a footing (see, for example, Patent Document 1).
In recent years, there has been proposed a joining method in which a steel pipe extending in the direction of the pile axis is welded to the upper end surface of the PHC pile, and a column base portion of a steel column is inserted into the steel pipe and concrete is placed ( For example, see Patent Document 2.)

  By the way, in the general joining method described above, in which the main reinforcing bars and whiskers of the pile are fixed in the footing, when a large earthquake occurs, the joint between the pile and the footing of the structure breaks, and the pile and the footing separate. There is a case. Moreover, in the above-mentioned joining method as described in Patent Document 1, when a large earthquake occurs, the pile head is pulled out of the joint concrete part, and the pile and the joint concrete part are separated, or the joint concrete part and In some cases, the joint with the footing breaks, and the pile and the footing in a state in which the joint concrete part is covered on the pile head are separated. Moreover, in the above-described joining method described in Patent Document 2, when a large earthquake occurs, the welded portion between the PHC pile and the steel pipe is broken, and the joint portion and the PHC pile in which concrete is placed in the steel pipe. May leave. As described above, when the existing pile and the existing foundation structure such as footing are detached, the axial force of the existing structure cannot be transmitted to the existing pile, and it has a great influence on the seismic performance of the existing structure. It is necessary to renovate the existing pile and the existing foundation structure.

As a conventional method of renovating existing foundations, a method of forming a connection structure made of reinforced concrete that connects the existing pile and the existing foundation structure between the separated existing pile and the existing foundation structure is used. . This connecting structure is formed by arranging reinforcing bars between existing piles and existing foundation structures, and then building concrete and placing concrete.
JP 2004-162455 A JP 2004-162374 A

However, although the existing existing foundation repair method described above can join the existing pile separated and the existing foundation structure, the stress state changed greatly by the separation of the existing pile and the existing foundation structure. There is a problem that it cannot be restored to its original state.
In addition, in the above-described conventional methods for renovating existing foundations, the connection structure is reinforced concrete, so it is necessary to perform rebar reinforcement and formwork erection of the joint structure below the narrow existing foundation structure. There is a problem that productivity is poor and cost is high. In addition, under the existing unstable foundation structure that has separated from the foundation pile, the reinforcement structure of the joint structure and the formwork installation work will be carried out, so there is also a problem in safety, ensuring safety. It takes a considerable amount of cost to do.

  The present invention takes the above-mentioned conventional problems into consideration, and when repairing an existing foundation from which an existing pile and an existing foundation structure are detached, the original stress state is restored to ensure excellent structural performance. The purpose is to provide a repair structure and a repair method for existing foundations, and to improve productivity, safety and economy.

  The invention according to claim 1 is a repair structure of an existing foundation in which a connection structure for joining the existing pile and the existing foundation structure is formed between the existing pile and the existing foundation structure separated by an external force. Between the existing pile and the existing foundation structure, an expansion / contraction mechanism embedded in the connection structure and extending / contracting in the pile axis direction to press the existing pile is interposed.

  By such a feature, a predetermined axial force is introduced into the existing pile by pressing (preloading) the existing pile separated from the existing foundation structure with an extension mechanism.

  According to a second aspect of the present invention, in the repair structure of the existing foundation according to the first aspect, the connection structure extends in a pile axis direction and is a first cement system in an outer steel pipe that accommodates the expansion / contraction mechanism. It is characterized by comprising a structure filled with a solidifying material.

  Such a feature eliminates the need for reinforcing bar arrangement or formwork construction when forming the connection structure.

  According to a third aspect of the present invention, in the repair structure of the existing foundation according to the first or second aspect, the upper end portion of the existing pile covers the upper end surface and the outer peripheral surface of the upper end portion of the existing pile, and the connection structure body. A reinforcing structure inserted into the structure is formed, and the existing pile is pressed by the expansion and contraction mechanism through the reinforcing structure.

  With such a feature, the upper end portion of the existing pile that receives the pressing force by the expansion and contraction mechanism is reinforced by the reinforcing structure.

  According to a fourth aspect of the present invention, in the repair structure of the existing foundation according to the third aspect, the reinforcing structure extends in the direction of the pile axis mounted with a gap between the outer peripheral surface of the upper end of the existing pile. The present invention is characterized in that the existing steel pipe is filled with a second cement-based solidifying material.

  Due to such a feature, when reinforcing structures are formed, it is not necessary to reinforce the reinforcing bars and to build the formwork.

  The invention according to claim 5 is a method for repairing an existing foundation in which the existing foundation structure and the existing pile are joined by forming a connection structure between the existing foundation structure and the existing pile separated by an external force. Inserting an expansion / contraction mechanism between the existing pile and the existing foundation structure to expand and contract in the axial direction of the pile and press the existing pile, and pressing the existing pile by the expansion / contraction mechanism And the step of forming the connection structure.

  With such a feature, the existing pile and the existing foundation structure are connected in a state where the existing pile is pressed and a predetermined axial force is introduced into the existing pile.

  According to the repair structure and the repair method of the existing foundation according to the present invention, a predetermined axial force is introduced into the existing pile by pressing the existing pile separated from the existing foundation structure with an extension mechanism. The existing foundation from which the existing foundation structure is detached can be returned to the original stress state, and excellent structural performance can be ensured.

  In addition, the connection structure that joins the existing foundation structure and the existing piles has a structure in which the outer steel pipe is filled with cement-based solidification material, which eliminates the need for reinforcing bar arrangement and formwork installation. Productivity, safety and economy can be improved.

  Moreover, the upper end part of the existing pile which receives the pressing force by an expansion-contraction mechanism is reinforced by setting it as the structure which formed the reinforcement structure which coat | covers the upper end surface and upper end part outer peripheral surface of an existing pile, respectively at the upper end part of the existing pile. Since it is reinforced by the structure, it is possible to prevent the upper end portion from being damaged by the pressing force of the expansion / contraction mechanism when pressing by the expansion / contraction mechanism, thereby introducing a large axial force to the existing pile. It becomes possible.

  In addition, the reinforcement structure formed at the upper end of the existing piles has a structure in which the internal steel pipe is filled with cement-based solidification material, which eliminates the need for reinforcing bar reinforcement and formwork erection. , Safety and economy can be improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an existing foundation repair structure and repair method according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a repair structure of an existing foundation, and FIG. 2 is a cross-sectional view taken along the line A-A shown in FIG. 1 and showing a repair structure of the existing foundation.

First, the repair structure of the existing foundation will be described.
The existing foundation in the present embodiment is the one in which the upper end surface of the existing pile 1 and the bottom surface of the existing foundation structure 2 such as a footing are originally joined. As shown in FIG. The existing pile 1 and the existing foundation structure 2 are separated from each other, and the pile upper end surface of the existing pile 1 and the bottom surface of the existing foundation structure 2 are separated from each other, so that the pile upper end surface of the existing pile 1 and the existing foundation structure 2 A gap is formed between the bottom surface.

  As shown in FIGS. 1 and 2, a reinforcing structure 3 that covers the upper end surface of the existing pile 1 and the outer peripheral surface of the upper end portion is formed at the upper end portion of the existing pile 1. The reinforcing structure 3 is provided in a state of being inserted into a lower part of a connection structure 11 described later, and is a non-shrink mortar as a cement-based solidified material in a cylindrical inner steel pipe 4 extending in the pile axis direction. 5 is filled. The inner steel pipe 4 is covered with the existing pile 1 with a gap between the inner end of the existing pile 1 and the upper end of the inner steel pipe 4 is higher than the upper end face of the existing pile 1. Is arranged. On the upper end surface of the inner steel pipe 4, a flat lid member 6 that is a plane perpendicular to the axis of the inner steel pipe 4 is placed. The lid member 6 is an octagonal steel plate that covers the upper end surface of the inner steel pipe 4 and covers the upper end surface of the inner steel tube 4, and is obtained by cutting four corners of a rectangular steel plate. The lid member 6 and the inner steel pipe 4 are welded along the outer periphery of the inner steel pipe 4. The non-shrink mortar 5 is formed between the outer peripheral surface of the upper end portion of the existing pile 1 and the inner peripheral surface of the inner steel pipe 4 or between the upper end surface of the existing pile 1 and the inner side surface (lower surface) of the lid member 6. The gaps are filled evenly.

  Between the existing pile 1 and the existing foundation structure 2 in which the reinforcement structure 3 was formed in the upper end part, the expansion-contraction mechanism 7 which expands-contracts in a pile axial direction and presses the existing pile 1 is interposed. The expansion / contraction mechanism 7 is provided in a state of being embedded in a connection structure 11 to be described later, and a flat plate-like lower member 8 that comes into contact with the upper surface of the lid member 6 and the bottom surface of the existing foundation structure 2. From the plate-shaped upper member 9 to be abutted, and a plurality (four in FIG. 2) of support jacks 10 extending in the pile axis direction interposed between the lower member 8 and the upper member 9. It is configured. The lower member 8 is made of a rectangular steel plate placed on the lid member 6, and the upper member 9 is made of a rectangular steel plate installed on the bottom surface of the existing foundation structure 2. The lower member 8 and the upper member 9 are members of substantially the same shape, and are disposed at positions that face each other vertically. The support jack 10 is a manual support jack having a configuration in which a post 10b is inserted into a cylindrical body 10a and screwed together, and a large capacity jack for 100t, for example, is used. The support jack 10 has a lower end fixed to the lower member 8 and an upper end fixed to the upper member 9. Adjacent support jacks 10 are connected by a connecting member 15, and a plurality of support jacks 10 are integrated. Further, the support jacks 10 are respectively disposed at the four corners of the lower member 8 and the upper member 9, and are disposed at positions directly above the upper end surface of the inner steel pipe 4.

  Moreover, between the existing pile 1 and the existing foundation structure 2, the connection structure 11 which joins the detached existing pile 1 and the existing foundation structure 2 is formed. The connection structure 11 is a structure suspended from the bottom surface of the existing foundation structure 2, and a non-shrink mortar 13 is used as a cement-based solidified material in a cylindrical outer steel pipe 12 extending in the pile axis direction. It consists of a filled configuration. The outer steel pipe 12 is a cylindrical member having a larger diameter than the inner steel pipe 4, and the upper end thereof is in contact with the bottom surface of the existing foundation structure 2, and a gap is formed between the outer steel pipe 12 and the outer peripheral surface of the reinforcing structure 3. The reinforcing structure 3 is opened and covered. Moreover, the outer steel pipe 12 is arrange | positioned so that the lower end may be lower than the upper end surface of the reinforcement structure 3, and may be above the lower end surface of the reinforcement structure 3, From the lower end of the outer steel pipe 12 (connection structure 11) The reinforcing structure 3 is in a protruding state. Further, the outer steel pipe 12 is composed of half steel pipes 12a and 12b having a semicircular cross section formed by dividing a cylindrical steel pipe into a plurality (two in FIG. 2) in the axial direction, and two half steel pipes 12a. , 12b are combined so that the inner side surfaces thereof face each other, and the joint portion 14 is welded. The non-shrink mortar 13 is evenly filled between the outer peripheral surface of the reinforcing structure 3 and the inner peripheral surface of the outer steel pipe 12 and around the expansion / contraction mechanism 7.

Next, a method for renovating the existing foundation will be described.
First, the process which digs up the location from which the existing pile 1 and the existing foundation structure 2 separated is performed. Specifically, the bottom of the existing foundation structure 2 is excavated to expose the lower surface of the existing foundation structure 2, and the periphery of the existing pile 1 is excavated to expose the upper end of the existing pile 1.

  Next, the process of forming the reinforcement structure 3 in the upper end part of the existing pile 1 is performed. Specifically, the lid member 6 is welded and integrated with the end surface of the inner steel pipe 4 in advance. And the inner steel pipe 4 to which the cover material 6 was attached is put on the upper end part of the existing pile 1. FIG. And the inner steel pipe 4 of the inner steel pipe 4 is formed so that there are predetermined gaps between the inner peripheral face of the inner steel pipe 4 and the outer peripheral face of the existing pile 1 and between the bottom face of the cover member 6 and the upper end face of the existing pile 1. While positioning, the inner steel pipe 4 arrange | positioned in the predetermined position is temporarily fixed so that it may not move. Further, a not-shown formwork or the like that closes the lower end surface of the inner steel pipe 4 is installed along the outer periphery of the existing pile 1. Next, the non-shrinking mortar 5 is injected from an injection hole (not shown) formed in the lid 6 or the inner steel pipe 4 in advance, and the inner steel pipe 4 is filled with the non-shrinking mortar 5. The inner steel pipe 4 is covered with the upper end of the existing pile 1 without attaching the cover 6 to the end surface of the inner steel pipe 4, and the inner steel pipe 4 is filled with the non-shrink mortar 5. The lid member 6 may be placed on the end face and welded.

  Next, after the non-shrink mortar 5 in the inner steel pipe 4 is solidified, the lower member 8, the upper member 9, and the plurality of members are disposed between the existing pile 1 and the existing foundation structure 2 on which the reinforcing structure 3 is formed. The expansion and contraction mechanism 7 including the support jacks 10 is installed, and the process of pressing the existing pile 1 by expanding and contracting the expansion and contraction mechanism 7 is performed. Specifically, the plurality of support jacks 10 are respectively contracted, the lower member 8 is set on the lower side, the expansion / contraction mechanism 7 is placed on the lid member 6, and the upper member 9 is mounted on the existing foundation. The expansion / contraction mechanism 7 is disposed between the upper surface of the lid member 6 and the bottom surface of the existing foundation structure 2 so as to face the bottom surface of the structure 2. Next, by extending each of the plurality of support jacks 10..., The upper member 9 is brought into contact with the bottom surface of the existing foundation structure 2 and pressed against the existing pile 1 via the lower member 8 and the reinforcing structure 3. Is transmitted and the existing pile 1 is pressed. When a predetermined axial force is introduced into the existing pile 1, the support jacks 10 are fixed in an expanded / contracted state at that time by a locking pin (not shown). The lower member 8 may be fixed to the lid member 6 by bolts or welding not shown, and the upper member 9 is post-illustrated not shown to the bottom surface of the existing foundation structure 2. You may fix with an anchor, an adhesive agent, etc.

  Next, the process of forming the connection structure 11 by embedding the upper end part of the existing pile 1 to which the reinforcing structure 3 is attached and the expansion / contraction mechanism 7 inside the existing foundation structure 2 is performed. Specifically, the two half steel pipes 12a and 12b are combined so that the upper end of the existing pile 1 to which the reinforcing structure 3 is attached and the expansion and contraction mechanism 7 are sandwiched from both sides. The joining portion 14 is welded to form a cylindrical outer steel pipe 12. The upper end of the outer steel pipe 12 is brought into contact with the bottom surface of the existing foundation structure 2 and a predetermined gap is formed between the inner peripheral surface of the outer steel pipe 12, the outer peripheral surface of the inner steel pipe 4, and the expansion / contraction mechanism 7. In addition, the outer steel pipe 12 is positioned, and the outer steel pipe 12 disposed at a predetermined position is temporarily fixed so as not to move. Further, a not-shown mold or the like that closes the lower end surface of the outer steel pipe 12 is installed along the outer periphery of the inner steel pipe 4. A non-shrink mortar 13 is injected from an injection hole (not shown) formed in advance in the outer steel pipe 12, and the non-shrink mortar 13 is filled into the outer steel pipe 12.

  Finally, soil is put into the excavated portion, and the upper end portion of the existing pile 1 and the reinforcing structure 3, the connecting structure 11, and the existing foundation structure 2 are backfilled to complete the repair work of the existing foundation. .

  According to the repair structure and repair method for an existing foundation having the above-described configuration, the existing pile 1 and the existing foundation structure 2 separated by an external force are embedded in the connection structure 11 and expanded and contracted in the pile axis direction. Since the expansion / contraction mechanism 7 that presses the existing pile 1 is interposed, the predetermined pile force is applied to the existing pile 1 by pressing the existing pile 1 separated from the existing foundation structure 2 by the expansion / contraction mechanism 7. be introduced. As a result, the existing foundation from which the existing pile 1 and the existing foundation structure 2 are separated can be returned to the original stress state, and excellent structural performance can be ensured.

  Moreover, the connection structure 11 which joins the existing pile 1 and the existing foundation structure 2 is made into the structure by which the non-shrink mortar 13 was filled in the outer steel pipe 12, and the operation | work of reinforcement reinforcement and formwork erection Can be eliminated, and productivity, safety and economy can be improved.

  Moreover, the existing pile 1 which receives the pressing force by the expansion-contraction mechanism 7 is set as the structure by which the reinforcement structure 3 which coat | covers the upper end surface of the existing pile 1 and an upper end outer peripheral surface is formed in the upper end part of the existing pile 1, respectively. Since the upper end of the reinforced structure 3 is reinforced by the reinforcing structure 3, it is possible to prevent the upper end from being damaged by the pressing force of the expansion / contraction mechanism 7 when pressing by the expansion / contraction mechanism 7. It is possible to introduce a large axial force into the.

  Furthermore, the reinforcement structure 3 formed at the upper end of the existing pile 1 is configured such that the inner steel pipe 4 is filled with the non-shrink mortar 5 so that rebar reinforcement and formwork work are not required. , Productivity, safety and economy can be improved.

  The embodiment of the existing foundation repair structure and repair method according to the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the scope of the present invention. is there. For example, in the above-described embodiment, the telescopic mechanism 7 provided with the manual support jacks 10 having a configuration in which the post 10b is inserted into the cylindrical body 10a and screwed is used. The invention may be a jack having another mechanical configuration such as a scissor jack or a journal jack, may be a hydraulic jack, or the like, and may be the telescopic mechanism 7 having any configuration.

  In the above-described embodiment, the non-shrink mortars 5 and 13 are used as the cement-based solidifying material. However, the present invention uses a solidifying material made of concrete or other cement-based material as the cement-based solidifying material. May be.

In the above-described embodiment, the connection structure 11 extends in the pile axis direction and has a configuration in which the non-shrink mortar 13 is filled in the outer steel pipe 12 that accommodates the expansion and contraction mechanism 7. The inventions described in claims 1 to 3 may be a reinforced concrete connection structure.
Moreover, in above-mentioned embodiment, although the reinforcement structure 3 is formed in the upper end part of the existing pile 1, the invention described in Claim 1, 2, 5 of this application is reinforced in the upper end part of the existing pile. The structure may not be formed, and a configuration in which the expansion / contraction mechanism is directly placed on the upper end surface of the existing pile may be used.
Moreover, in above-mentioned embodiment, the non-shrink mortar is in the inner steel pipe 4 extended in the axial direction of the pile in which the reinforcing structure 3 is mounted with a gap between the upper end outer peripheral surface of the existing pile 1. However, the invention described in claim 3 of the present application may be a reinforced concrete structure.

It is a longitudinal cross-sectional view of the existing foundation for demonstrating embodiment of this invention. It is sectional drawing between AA shown in FIG.

Explanation of symbols

1 Existing pile 2 Existing foundation 3 Reinforced structure 4 Inner steel pipe 5 Non-shrink mortar (second cement-based solidified material)
7 Stretching mechanism 11 Connection structure 12 Outer steel pipe 13 Non-shrink mortar (first cement-based solidified material)

Claims (5)

In the repair structure of the existing foundation in which a connection structure that joins the existing pile and the existing foundation structure is formed between the existing pile separated by the external force and the existing foundation structure,
Rehabilitation of an existing foundation characterized in that an expansion / contraction mechanism is interposed between the existing pile and the existing foundation structure, which is embedded in the connection structure and extends and contracts in the direction of the pile axis to press the existing pile. Construction. In the repair structure of the existing foundation according to claim 1,
The said connection structure consists of the structure filled with the 1st cement-type solidification material in the outer steel pipe extended in a pile axial direction and accommodating the said expansion-contraction mechanism, The repair structure of the existing foundation characterized by the above-mentioned. In the modified structure of the existing foundation according to claim 1 or 2,
The upper end of the existing pile is formed with a reinforcing structure that covers the upper end surface and the outer peripheral surface of the upper end of the existing pile and is inserted into the connection structure, and the existing pile passes through the reinforcing structure. Renovation structure of an existing foundation, which is pressed by an expansion / contraction mechanism. In the repair structure of the existing foundation according to claim 3,
The reinforcing structure has a structure in which a second cement-based solidified material is filled in an inner steel pipe extending in the pile axial direction that is mounted with a gap between the upper end outer peripheral surface of an existing pile. Renovation structure of existing foundation, characterized by In the repair method of the existing foundation in which the existing pile and the existing foundation structure are joined by forming a connection structure between the existing pile and the existing foundation structure separated by external force,
Between the existing pile and the existing foundation structure, interposing an expansion / contraction mechanism that expands and contracts in the pile axis direction and presses the existing pile, and pressing the existing pile by the expansion / contraction mechanism;
And a step of forming the connection structure by embedding an expansion / contraction mechanism therein.

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