JP5769231B2 - Underground structure joint structure - Google Patents

Description

  The present invention, for example, when rebuilding a structure, an existing pile as a remaining underground structure and a new foundation as an underground structure of a new structure built on the existing pile are joined together. The present invention relates to a structure joint structure.

  When a building is demolished and rebuilt to a new building, the existing piles remaining in the ground can be reused as piles for new buildings along with new piles to be added to the designated location. This is economical from the viewpoint of saving a lot of time and is also economical, and can also prevent the generation of a large amount of waste, which is preferable from the viewpoint of reducing the burden on the environment.

  However, according to the current standards, the above piles are obligated to prevent damage against earthquakes (hereinafter referred to as assumed earthquakes) that are likely to be encountered once during the lifetime of the new building. Pile is generally designed according to the old standard at the time of construction, which was not established, so it has the desired vertical support capacity, but lacks the horizontal resistance capacity against the above-mentioned assumed earthquake. Results In many cases, the piles cannot be reused under the same load conditions as the new piles.

  In order to solve this problem, a method has been proposed in which a device is interposed between the existing pile and the new foundation, and the pile head joint is pin-joined or roller-jointed, but it requires manufacturing and installation of the device. There were problems with economy and workability.

  For this reason, for example, in the following Patent Document 1, an existing pile is used in combination with an existing pile, in which only the vertical load is borne and the new pile is loaded with both a vertical load and a horizontal load. The basic structure of a new building has been proposed.

  Moreover, in the following patent document 2, when constructing the upper structure, the upper structure is separated by vertically separating the bottom surface of the upper structure and the upper end of the existing pile, and a cushioning material is interposed between them. By providing a shear key consisting of a round bar or the like that can support the load of the structure only on the new pile and transmit the horizontal force between the upper end of the existing pile and the upper structure, A method of rebuilding a building that is sometimes used to bear the horizontal force of the superstructure has been proposed.

  However, in the conventional foundation structure described in Patent Document 1, it is a structure that does not bear a horizontal load at all on the existing pile. On the other hand, in the building rebuilding method described in Patent Document 2, the existing pile is vertically Since these structures do not bear a load, the pile diameter and number of new piles to be placed in the construction of a new building will increase, and there are various problems in terms of workability and economy. It was.

  In addition, in the rebuilding method described in Patent Document 2 in which a horizontal load is borne on the existing pile, the shear key is surrounded by the compressed cushioning material, so that the horizontal direction between the superstructure and the existing pile at the time of the earthquake is When relative displacement occurs, there is a problem that a large deformation performance cannot be obtained, and therefore the horizontal force cannot be borne by breaking before the desired shear strain is generated.

  Then, in the following patent document 3, the existing pile which formed the space | gap part around the shearing force transmission member by which one end part is fixed to the existing pile, and the other end part is fixed to a new foundation, and improved the deformation performance. And foundation structures using new piles have been proposed.

  According to the proposal shown in Patent Document 3, a vertical load from a new foundation can be borne on an existing pile, and when a horizontal force acts during an earthquake, the existing pile is leveled by the shear force transmission member. You can bear power. In addition, even when a horizontal relative displacement occurs between the new foundation and existing piles, the entire new structure constructed on the new foundation by yielding the shear force transmission member and absorbing its hysteresis energy The safety at the time of earthquake can be improved.

Japanese Patent Laid-Open No. 09-060007 JP 2002-256571 A JP 2009-91730 A

  However, in Patent Document 3, when the shear force transmission member is plasticized due to an assumed earthquake, the strength increases due to strain hardening, and thus there is a possibility that a horizontal force exceeding the horizontal resistance capability may act on the existing pile. In addition, there is a possibility that the shear force transmitting member may be fatigued.

  The present invention has been made in view of such circumstances, and in an underground structure joint structure that joins underground structures stacked up and down underground like existing piles and new foundations, It is an object of the present invention to provide an underground structure joint structure that can easily ensure the soundness of the assumed earthquake.

In order to solve the above-mentioned problem, the invention according to claim 1 is an underground structure joint structure that joins underground structures stacked one above the other in the underground, and the upper and lower underground structures contact each other. On the upper side of the surface, a recess is formed that forms a gap between the two, and on the lower surface of the recess, a plurality of lower holes extending downward from the lower surface of the recess are formed at lattice points forming a square . A cylindrical upper cylindrical member is provided in the upper structure at a position facing the lower hole on the upper surface, and an upper hole extending upward from the upper surface of the recess is formed by the upper cylindrical member. is, in the recess, steel shearing force transmitting member lower end portion is unfixed is inserted into the lower hole with the upper end portion is inserted into the upper hole is arranged interchangeably, The upper hole is closed with a detachable water stopcock. It is an butterfly.

Here, as the shearing force transmission member, a rod-shaped member using extremely low yield point steel is suitable, but depending on the depth of the concave portion or the like, a rod-shaped member made of steel such as ordinary steel or a large-diameter rebar Can also be used.
In addition, specifications such as the number, material, cross-section, length, etc. of the shear force transmitting members arranged in the recess may be selected so that the horizontal force borne by the existing piles will yield before reaching its proof strength. preferable.

Further, in the present invention, in the invention described in claim 1, wherein the recess is preferably formed on at least one of the central portion of the abutment surface of the subsurface structure between the upper and lower.

Furthermore, in the present invention, an internal pre-Symbol recess, and on the outside of the arrangement of the installation position four sides of the shear force transmitting member, together with the lower end portion is fixed to the subsurface structure of the lower, upper A stopper having an end protruding beyond the level of the contact surface in the recess is provided .

  By the way, the distance between the other end of the stopper and the other of the upper and lower underground structures that are displaced relative to the stopper causes an earthquake that is larger than the assumed earthquake according to the current standard described above. When a relative displacement occurs between the other underground structure, it is preferable to set the dimension so that the stopper abuts against the relatively displaced underground structure to prevent the horizontal displacement.

Further, in the present invention, in the invention described in claim 1, between the subsurface structure between said upper and lower, it is preferable that the friction reduction member to reduce friction between them is interposed.

In the present invention, in the invention according to claim 1, the lower underground structure is an existing pile or existing foundation left in the ground by removing the existing structure, and the upper underground structure The body is preferably a new foundation constructed on the existing pile or existing foundation.

In the present invention, in the invention according to claim 1, the lower underground structure is a new pile, and the upper underground structure is a new foundation constructed on the new pile. Is preferred .

According to the first aspect of the present invention, at least one of the contact surfaces of the upper and lower underground structures is formed with a recess that forms a gap between the two, and an upper hole penetrating the new foundation is formed on the upper part. A bottomed bottom hole is formed in the lower portion of the concave portion at a position facing this, and the upper end portion is inserted into the upper hole and the lower end portion is inserted into the lower hole in the concave portion to be unfixed. Since a plurality of shear force transmission members are arranged, the lower underground structure is caused to bear a vertical load from the upper underground structure via the contact surfaces of both of which the recess is not formed. be able to.

  Further, when a horizontal force acts during an earthquake, the shear force can be transmitted from the upper underground structure to the lower underground structure by the shear force transmitting member. At this time, since the shearing force transmitting member is disposed in the gap formed in the recess, a large deformation performance can be ensured. For this reason, it is possible to suppress shear strain and prevent early breakage, and by adjusting the strength of the shear force transmitting member, a large gap is formed between the upper underground structure and the lower underground structure. Even when a relative displacement occurs, the shear force transmission member is yielded, and the safety at the time of earthquake of the whole new structure constructed on the new foundation can be improved by absorbing the hysteresis energy.

  Furthermore, since the shear force transmission member is inserted into the upper hole and the lower hole and is not fixed, even if the strength of the shear force transmission member increases due to strain hardening accompanying plasticization after the earthquake, the shear force transmission member By removing a part of the horizontal force, it becomes easy to keep the horizontal force transmitted by the shearing force transmission member below a predetermined numerical value. In addition, when plastic deformation repeatedly occurs in the shear force transmission member and there is a risk of fatigue failure, it can be replaced with a new one. Therefore, the soundness of the lower underground structure at the time of the assumed earthquake can be ensured reliably and easily.

As a result, the lower underground structure can be loaded with corresponding vertical and horizontal loads, and the lower underground structure is prevented from being damaged by the above-mentioned earthquake, making full use of its performance. Can be reused. In addition, this makes it possible to reduce the vertical load and horizontal force to be borne by the newly built pile, so that the cross section and the amount of reinforcing bars can be reduced. Construction period or cost can be reduced.
Further, since the shearing force transmission member can be easily removed and replaced without generating noise, the maintenance work after the earthquake is rationalized.

Here, as described above , if the concave portion is formed in the central portion of at least one of the contact surfaces of the upper and lower underground structures, the vertical load from the upper underground structure can be reduced evenly over a wide area. It is preferable that it can be transmitted to the underground structure on the side.

In addition, as described above, when a stopper is provided inside the recess and on the outer peripheral side of the position where the shear force transmission member is disposed , when an earthquake larger than the assumed earthquake described above occurs In this case, since the stopper restrains the horizontal displacement of the upper or lower underground structure that is relatively displaced, the shear force transmission member can be prevented from being excessively deformed and broken.

Furthermore, for existing piles where high axial force acts, such as existing piles directly under the pillar, the frictional force at the contact surface increases, resulting in shear force transmission by the shear force transmission member and its yield. There is a possibility that the history energy absorption is not smoothly performed. Such locations are, as described above, when interposed friction reducing member between the abutment surface of each other, thereby reducing the frictional force, exert the desired function shear force transmitting member be able to.

It is a longitudinal cross-sectional view which shows the arrangement | positioning of the existing pile and existing pile of the existing building which concern on one Embodiment of this invention. It is a pile pile figure of the building concerning the embodiment. It is a longitudinal cross-sectional view of the junction part of the existing pile and new foundation of the building which concerns on the said embodiment. It is a cross-sectional view of the junction part of the existing pile of the building which concerns on the said embodiment, and a new foundation. It is sectional drawing (the 1) for demonstrating the procedure which builds the junction part of the existing pile of the building which concerns on the said embodiment, and a new foundation. It is sectional drawing (the 2) for demonstrating the procedure which builds the junction part of the existing pile of the building which concerns on the said embodiment, and a new foundation. It is sectional drawing (the 3) for demonstrating the procedure which builds the junction part of the existing pile of the building which concerns on the said embodiment, and a new foundation. It is a longitudinal cross-sectional view which shows the behavior at the time of the earthquake occurrence of the building which concerns on the said embodiment. It is a longitudinal cross-sectional view of the junction part of the existing pile of the building which concerns on the 1st modification of this invention, and a new foundation. It is a longitudinal cross-sectional view of the junction part of the existing foundation and new foundation of the building which concerns on the 2nd modification of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Drawing 1 is a longitudinal section showing arrangement of an existing pile and new pile of building 2 concerning one embodiment of the present invention. FIG. 2 is a pile profile of the building 2.
For example, as shown in FIG. 1, the basic structure of the building 2 is applied when removing the existing building 1 as an existing structure having 6 stories above the ground and rebuilding it into a building 2 having 9 stories above the ground. The existing pile 3 as an underground structure below the existing building 1, the new pile 4 placed at a predetermined position away from the existing pile 3, and the existing pile 3 and the new pile 4 And a new foundation 5 as an upper underground structure constructed.

3 and 4 are a longitudinal sectional view and a transverse sectional view of a joint portion between the existing pile 3 and the new foundation 5.
As for the existing pile 3, the pile head part is beaten to the predetermined depth, and the main reinforcement and the strip are removed, and the new foundation 5 is constructed | assembled on the existing pile 3 from which this pile head part was removed.

A lower concave portion 10 having a predetermined depth dimension is formed in the central portion of the contact surface 3a that contacts the new foundation 5 of the existing pile 3. The lower concave portion 10 is filled with a grout material and closed, thereby forming a grout material filling portion 11. This grout material filling part 11 and the contact surface 3a of the existing pile 3 are flush with each other.
In addition, an upper concave portion 20 having a slightly larger planar dimension than the lower concave portion 10 is also formed on the contact surface 5 a that contacts the existing pile 3 of the new foundation 5.

The grout material filling portion 11 is formed with a lower hole 12 extending downward from the surface of the grout material filling portion 11, that is, the lower surface of the upper recess 20. The lower hole 12 extends to the vicinity of the bottom surface of the lower recess 10 of the existing pile 3.
An upper hole 21 extending upward from the upper surface of the upper recess 20 and penetrating through the new foundation 5 is formed at a position facing the lower hole 12 on the upper surface of the upper recess 20.

Between the new foundation 5 and the existing pile 3, a plurality of pieces (in this embodiment, 3 × 4 in which one end portion is inserted into the upper hole 21 and the other end portion is inserted into the lower hole 12 and are not fixed. = 12) dowel steel members 30 as shear force transmission members are arranged.
Here, each dowel steel material 30 is a bar-shaped member having a rectangular cross section made of extremely low yield point steel.
Further, the upper end portion of the upper hole 21 is closed with a detachable water stop cock 22.

Furthermore, a stopper 31 is disposed along the four sides of the grout material filling portion 11 which is a planar rectangular shape of the existing pile 3 and on the outer peripheral side of the dowel steel material 30.
These stoppers 31 are made of rectangular steel plates, reinforcing bars, concrete, or the like, and are located at a predetermined distance from the inner surface of the lower recess 10 with the side surfaces of the stopper 31 being parallel to the inner surface of the lower recess 10. Is arranged.
Each stopper 31 protrudes from the surface of the grout material filling portion 11 into the upper concave portion 20 of the new foundation 5. The lower part of the stopper 31 is fixed to the grout material filling part 11.

Here, the cross-sectional dimension of the dowel steel material 30 and the depth dimension of the upper concave portion 20 yield before the horizontal force borne by the existing pile 3 reaches the proof stress of the existing pile 3 when the above-mentioned assumed earthquake occurs. Is set to
The cross-sectional shape of the dowel steel material 30 and the planar shape of the upper concave portion 20 are not limited to a rectangular shape, and may be other shapes such as a circular shape.

  In addition, the distance between the upper portion of the stopper 31 and the inner side surface of the upper concave portion 20 of the new foundation 5 is such that the stopper 31 and the inner side surface of the upper concave portion 20 do not contact each other even in the case of the assumed earthquake, and the assumed earthquake. When a larger earthquake occurs and a large horizontal displacement occurs between the existing pile 3 and the new foundation 5, the stopper 31 comes into contact with the inner surface of the upper recess 20 of the newly installed foundation 5 that is horizontally displaced. The dimensions are set so as to prevent the horizontal displacement.

The basic structure of the building 2 having the above configuration is constructed by the following procedure.
That is, as shown in FIG. 5, first, after dismantling the existing building 1, the pile head of the existing pile 3 is rolled to a predetermined depth, the main bar is cut and the band is removed, and the center of the upper surface of the existing pile 3 is removed. The lower concave portion 10 provided in is formed.
Next, the stopper 31 is installed at a predetermined position and level in the lower recess 10, and the cylindrical lower cylindrical member 13 having an inner diameter larger than the dowel steel material 30 is installed at a predetermined position.

  Next, as shown in FIG. 6, the grout is filled up to the level of the contact surface 3 a of the existing pile 3 and solidified to form the grout material filling portion 11. Note that concrete or mortar may be filled instead of grout. Thereby, the inside of the lower cylindrical member 13 becomes the lower hole 12.

Next, the spacer 14 is put on the upper surface of the grout material filling part 11. The spacer 14 is for forming the upper concave portion 20 and has a box shape. At this time, instead of the spacer 14, a foam material such as styrene or styrofoam can be used.
Further, a cylindrical upper cylindrical member 15 having an inner diameter larger than that of the dowel steel material 30 is placed on the spacer 14 and installed at a position facing the lower cylindrical member 13. 14 communicate with the inside. The height of the upper cylindrical member 15 is set to a height that penetrates the new foundation 5.

  Next, as shown in FIG. 7, after arranging the new foundation 5, concrete is cast and the new foundation 5 is constructed. As a result, an upper concave portion 20 serving as a gap defined by the spacer 14 is formed on the lower surface of the new foundation 5, and the inside of the upper cylindrical member 15 becomes the upper hole 21.

  Next, the dowel steel material 30 is inserted into the lower hole 12 made of the lower cylindrical member 13 through the upper hole 21 made of the upper cylindrical member 15, and then the water stop cock 22 is fitted into the upper end portion of the upper hole 21.

According to this embodiment, there are the following effects.
Of the contact surfaces 3a, 5a of the existing pile 3 and the new foundation 5, an upper concave portion 20 is formed on the new foundation 5 side of the contact surface 5a. The upper end portion is fixed to the newly-founded foundation 5 and the lower end portion is disposed in the grout material filling portion 11 that closes the lower concave portion 10 of the existing pile 3. The vertical load from the newly installed foundation 5 can be borne by the existing pile 3 through the contact surfaces 3a and 5a of the portion where no is formed.

  In addition, as shown in FIG. 8, when a horizontal force acts during an earthquake, a shear force can be transmitted from the new foundation 5 to the existing pile 3 via the dowel steel material 30. At this time, since the dowel steel material 30 is disposed in the upper concave portion 20 serving as a gap, a large deformation performance can be ensured. For this reason, it is possible to suppress shear strain and prevent early breakage, and even when a large relative displacement occurs between the new foundation 5 and the existing pile 3, the dowel steel 30 is yielded. And the safety at the time of earthquake of the whole building 2 constructed | assembled on the new foundation 5 can also be improved by the hysteresis energy absorption.

  Furthermore, since the dowel steel material 30 is inserted into the upper hole 21 and the lower hole 12 and is not fixed, even when the strength of the dowel steel material 30 increases due to strain hardening accompanying plasticization after the earthquake, the dowel steel material 30 By removing a part, it becomes easy to keep the horizontal force transmitted by the dowel steel material 30 below a predetermined numerical value. Further, when plastic deformation is repeatedly generated in the dowel steel material 30 and there is a risk of fatigue failure, it can be replaced with a new one. Therefore, the soundness of the existing pile 3 at the time of the assumed earthquake can be reliably and easily ensured.

  In addition, since the stopper 31 is provided on the outer peripheral side in the lower concave portion 10 and on the outer peripheral side with respect to the position where the dowel steel material 30 is disposed, in the case where an earthquake larger than the above-described assumed earthquake occurs In addition, the dowel steel material 30 can be prevented from being excessively deformed and broken by abutting the inner surface of the upper recess 20 of the new foundation 5 to which the stopper 31 is relatively displaced and restraining the horizontal displacement thereof.

  Moreover, since the upper side recessed part 20 was formed in the center part of the contact surface 3a of the existing pile 3 and the new foundation 5, it is possible to transmit the vertical load from the new foundation 5 to the existing pile 3 evenly over a wide area. it can.

As a result, it is possible to bear the corresponding vertical load and horizontal load on the existing pile 3 as well as to prevent the existing pile 3 from being damaged due to the above-mentioned assumed earthquake and to reuse the performance sufficiently. it can. Thereby, since the vertical load and horizontal force which should be borne by the new pile 4 can be reduced, the cross section and the amount of reinforcing bars can be reduced, thereby reducing the resources, construction period or cost required for construction. be able to.
Further, since the dowel steel 30 can be easily removed and replaced without generating noise, the maintenance work after the earthquake is rationalized.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

  For example, in this embodiment, although all demonstrated only the case where the existing pile 3 is a solid pile, as shown in FIG. 9, the existing pile 7 is a pile of a hollow cross section. In some cases, the pile head can be filled with concrete in advance, and the lower recess 10 can be formed on the top surface of the filled concrete to place the dowel steel 30 and the stopper 31.

  Furthermore, not only the case where the new foundation 5 is constructed directly on the upper surface of the existing pile 3 and the above underground structure joint structure is applied between the two, the existing building 1 is placed on the existing pile 3 as shown in FIG. When the existing foundation 6 is provided, the existing foundation 6 can be left and the new foundation 5 can be constructed on the upper surface. In this case, the dowel steel material 30 and the stopper 31 may be disposed on the upper surface of the existing foundation 6 in the same manner by forming the lower concave portion 10.

  Further, the upper concave portion 20 is not necessarily limited to the case where it is provided on the new foundation 5 side, and may be formed on the upper surface of the existing pile 3 or the existing foundation 6 or the existing pile 3 (or the existing foundation 6). ) And the new foundation 5 can be formed with recesses communicating with each other. Moreover, in the underground structure joining structure which concerns on this invention, although the dowel steel material 30 which transmits a horizontal force is provided between the existing pile 3 or the existing foundation 6 mentioned above, and the newly established foundation 5, it is further a new pile. It is also possible to provide the dowel steel material 30 similarly between 4 and the new foundation.

  Moreover, the said structure of this invention can be diverted as a structure between a new pile and a new foundation which wants to prevent the damage at the time of an earthquake especially in an underground structure joining structure comprised only by a new pile. .

1 ... Existing building (existing structure)
2… Buildings 3, 7… Existing piles (underground structure)
3a ... Contact surface 4 ... New pile 5 ... New foundation (upper underground structure)
5a ... abutting surface 6 ... existing foundation 10 ... lower recess 11 ... grout material filling part 12 ... lower hole 13 ... lower cylindrical member 14 ... spacer 15 ... upper cylindrical member 20 ... upper recess 21 ... upper hole 22 ... stop Faucet 30 ... Dowel steel (shearing force transmission member)
31 ... Stopper

Claims (1)

An underground structure joint structure that joins underground structures stacked one above the other in the basement,
On the upper side of the contact surface between the upper and lower underground structures, a recess is formed that forms a gap between them,
On the lower surface of the concave portion, a plurality of lower holes extending downward from the lower surface of the concave portion are formed at lattice points forming a square ,
A cylindrical upper cylindrical member is provided in the upper structure at a position facing the lower hole on the upper surface of the concave portion, and the upper portion extends upward from the upper surface of the concave portion by the upper cylindrical member. Holes are formed,
The said recess, steel shearing force transmitting member lower end portion is unfixed is inserted into the lower hole with the upper end portion is inserted into the upper hole is arranged interchangeably,
The upper hole is closed with a detachable water stop cock,
A lower end is fixed to the lower underground structure inside the recess and outside the four sides of the position where the shear force transmission member is disposed, and an upper end is fixed to the contact in the recess. An underground structure joint structure characterized by being provided with a stopper protruding beyond the level of the contact surface .

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