JP5074152B2 - Foundation structure - Google Patents

Description

  It relates to the foundation structure of ground recesses such as seismic isolation pits.

  The seismic isolation pit includes a bottom plate that supports the structure and a peripheral wall formed around the bottom plate. A seismic isolation clearance is secured between the peripheral wall and the structure so that the structure does not come into contact with the peripheral wall when the seismic isolation device is activated and the structure moves horizontally during an earthquake.

  In such a method of building a seismic isolation pit, first, a mountain retaining wall was constructed to prevent the surrounding ground from collapsing so as to enclose the area where the seismic isolation pit was to be installed, and was then surrounded by the mountain retaining wall. The ground in the area will be excavated from the ground surface to the bottom of the root. After that, the above-mentioned seismic isolation pit (bottom and peripheral wall) is constructed in the ground recess surrounded by the mountain retaining wall. In addition, when a steel core is used for the mountain retaining wall, the core is not recovered after the construction.

  And the structure which simplifies the structure of a surrounding wall using the temporary mountain retaining wall used when constructing a base isolation pit as a main structure of the surrounding wall of a base isolation pit is proposed (for example, patent document 1). reference).

Moreover, in the retaining wall constructed by inserting the reinforcing core material into the drilling hole before the strength of the filler filled in the drilling hole is expressed, the part where the horizontal resistance is required among the plurality of parts in the vertical direction of the retaining wall A method for reinforcing a retaining wall has been proposed in which a high-strength filler is used for the general portion and a low-strength filler is used for the general portion to increase the rigidity of a portion where horizontal resistance is required (see, for example, Patent Document 2).
JP 2004-044203 A Japanese Patent Laid-Open No. 2005-282043

  Now, it is desired to improve the horizontal resistance force at the time of an earthquake in a foundation structure provided in a ground recess (pit) formed by excavating the ground such as a seismic isolation pit at low cost.

  The present invention has been made to solve the above problems, and an object thereof is to improve the horizontal resistance of the foundation structure of the ground recess.

Basic structure according to claim 1, provided at the bottom of the ground recess, a peripheral wall which also serves as the foundation bottom panel for supporting a structure, the mountain Tomekabe before Symbol ground recess co If surround the foundation bottom plate, but the structure a seismic isolation pit that is integral to, said peripheral wall of said seismic isolation pit is characterized by and a Kabekui formed by being extended to below the lower surface of the base bottom panel.

  In the foundation structure of Claim 1, since the wall pile extended below from the surrounding wall which also serves as the mountain retaining wall of a ground recessed part has horizontal resistance, the horizontal resistance of a foundation bottom is reinforced. That is, the horizontal resistance of the foundation structure is improved. Thereby, the inertia force at the time of earthquake of the structure provided on the foundation bottom is efficiently transmitted to the ground.

Moreover, since the foundation bottom and the peripheral wall are structurally integrated, the inertial force at the time of earthquake of the structure provided on the foundation bottom is more efficiently transmitted to the ground. Furthermore, in addition to reinforcing the horizontal resistance of the foundation bottom, the vertical resistance of the foundation bottom is also reinforced.

The foundation structure according to claim 2 is the structure according to claim 1 , wherein the wall piles are provided at intervals.

In the foundation structure according to claim 2 , for example, the peripheral wall having a sufficient horizontal resistance force is provided with wall piles at intervals, whereby the horizontal resistance force of the foundation bottom is reinforced at low cost.

According to a third aspect of the present invention , in the structure according to the first or second aspect, the peripheral wall is formed with a protruding wall protruding outward.

In the basic structure according to the third aspect, since the rigidity in the out-of-plane direction of the peripheral wall on which the protruding wall is formed is improved by the protruding wall, the horizontal resistance is improved. As a result, the horizontal resistance of the foundation bottom is reinforced.

The basic structure according to claim 4 is the structure according to any one of claims 1 to 3 , wherein the peripheral wall has a substantially rectangular shape in plan view, and the peripheral wall includes a corner portion of the peripheral wall. In this case, an extending wall that extends outward in both directions from the corner is formed so as to form a cross shape in plan view with the peripheral wall .

In the foundation structure according to the fourth aspect, the horizontal resistance force of the peripheral wall is improved by the extending wall, and as a result, the horizontal resistance force of the foundation bottom is reinforced.

  As described above, according to the present invention, there is an excellent effect that the horizontal resistance of the foundation structure of the ground recess can be improved.

  The basic structure of the first embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, a seismic isolation pit 100 is provided in a ground recess 50 formed by excavating the upper ground 28. In the present embodiment, the upper layer ground 28 includes a first layer 22, a second layer 24, and a third layer 26 from the top. Although FIG. 1 is a longitudinal sectional view, the diagonal lines representing the cross section are drawn only on the upper layer ground 28 and the lower layer ground 30 in order to avoid complication of the drawing.

  The seismic isolation pit 100 has a reinforced concrete foundation bottom plate 102 that is formed at the bottom of the ground recess 50 and supports the structure 16. The foundation bottom plate 102 is supported by the pile 40. Note that the lower end portion 40 </ b> A of the pile 40 is inserted into the hard lower layer ground 30 below the upper layer ground 28.

  A seismic isolation device 12 is provided on the foundation bottom plate 102. The seismic isolation measure 12 is provided immediately above the pile 40. On the seismic isolation device 12, a seismic isolation frame 14 (a foundation beam directly above the seismic isolation device 12) is provided, and a structure 16 is provided on the seismic isolation frame 14. In the present embodiment, the seismic isolation device 12 has a structure in which a lead pillar is inserted into a laminated rubber body in which rubber plates and steel plates are alternately laminated in the thickness direction, but is not limited thereto. Other seismic isolation devices may be used.

  As shown in FIGS. 1 and 2, the seismic isolation pit 100 is provided with a peripheral wall 104 surrounding the side surface 102 </ b> A of the foundation bottom base 102. The peripheral wall 104 also serves as a mountain wall for the ground recess 50. A wall pile 106 extends from the peripheral wall 104 below the lower surface 102B of the foundation bottom plate 102 (the bottom surface of the ground recess 50). The peripheral wall 104 and the side surface 102A of the foundation bottom plate 102 are joined, and the peripheral wall 104 and the foundation bottom plate 102 are structurally integrated.

  Further, as shown in FIG. 1, when the seismic isolation device 12 is activated and the structure 16 (base isolation rack 14) behaves horizontally during an earthquake, the structure 16 (base isolation rack 14) contacts the peripheral wall 104. In order to prevent this, a seismic isolation clearance L is secured between the structure 16 (base isolation rack 14) and the peripheral wall 104.

  In the present embodiment, as shown in FIG. 2, the seismic isolation pit 100 has a rectangular shape in plan view. The short side of the rectangle is referred to as a peripheral wall 104S, and the long side is referred to as a peripheral wall 104L. Further, a structure constituted by the seismic isolation pit 100 (configured by the peripheral wall 104 including the wall pile 106 and the foundation bottom plate 102) and the pile 40 is defined as the foundation structure 10.

  Next, the case where the foundation structure 10 of the present embodiment is applied to the existing structure 16 supported by the pile 40, that is, seismic isolation repair of the existing structure 16 will be described.

  A peripheral wall 104 that also serves as a mountain retaining wall for the purpose of preventing the surrounding upper layer ground 28 (the first layer 22 and the second layer 24) from collapsing is formed so as to surround an area where the seismic isolation pit 100 is to be provided. For example, the peripheral wall 104 is constructed by inserting a reinforcing core material into the drilling hole before the strength of the filler filled in the drilling hole is developed. At this time, the wall pile 106 extending downward from the lower surface 102 </ b> B of the foundation base 102 is formed on the peripheral wall 104.

  Subsequently, the upper ground 28 in the region surrounded by the peripheral wall 104 (mountain wall) is excavated from the ground, and a temporary mount is installed to support the structure 16. The existing pile 40 is cut, and the foundation bottom board 102 is formed on the cut pile 40. Further, the foundation bottom plate 102 and the peripheral wall 104 are joined. As a result, a base-isolated pit 100 in which the foundation pile foundation bottom 102 and the peripheral wall 104 are structurally integrated is provided in the ground recess 50. Then, the base isolation frame 14 is provided, and the base isolation device 12 is installed between the base isolation base 14 and the foundation bottom base 102.

  Next, the operation of this embodiment will be described.

  Since the wall pile 106 that extends downward from the peripheral wall 102 that also serves as the mountain wall has horizontal resistance, the horizontal resistance of the foundation bottom plate 102 that supports the structure 16 is reinforced. That is, the horizontal resistance of the foundation structure 10 is improved. Thereby, the inertia force at the time of earthquake of the structure 16 provided on the foundation bottom 102 is efficiently transmitted to the upper ground 28.

  Further, in the present embodiment, the peripheral wall 104 and the side surface 102A of the foundation bottom plate 102 are joined, and the peripheral wall 104 and the foundation bottom plate 102 are structurally integrated. Therefore, not only when the base bottom plate 102 moves so as to push the peripheral wall 104 outward, but also when the base bottom plate 102 moves in the opposite direction (in the direction away from the peripheral wall 104), the inertia force during the earthquake of the structure 16 is increased. It is transmitted to the upper ground 28. That is, the earthquake inertia force of the structure 16 is transmitted to the upper ground 28 more efficiently. Furthermore, in addition to reinforcing the horizontal resistance force of the foundation bottom plate 102, the vertical resistance force of the foundation bottom plate 102 is also reinforced.

  Now, when the seismic isolation repair is performed, the weight of the seismic isolation rack 14, the seismic isolation pit 100, and the seismic isolation device 12 increases from before the seismic isolation repair. That is, the weight supported by the existing pile 40 increases.

  Therefore, the foundation structure 11 using the seismic isolation pit 800 (the seismic isolation pit 800 on which the wall pile 106 (see FIGS. 1 and 2A) is not formed) to which the present invention shown in FIG. In such a case, the horizontal resistance force at the time of an earthquake may be insufficient with only the pile 106.

  In such a case, as shown in FIG. 4, a method of driving a new pile 46 such as a press-fitted high pipe pile joined with the short pile 44 directly under the existing structure 16 (foundation base plate 102) can be considered. . However, the method of providing the new pile 46 directly under the existing structure 16 is difficult to construct. Even if construction is possible, the construction cost is high.

  Alternatively, as shown in FIG. 5, a method of adding a new pile 48 outside the existing structure 16 (the peripheral wall 804 of the seismic isolation pit 800) and joining it to the peripheral wall 104 can be considered. However, since the horizontal rigidity of the new pile 48 is not so high, a large number is required and the construction cost is high.

  On the other hand, the seismic isolation pit 100 of this embodiment shown in FIGS. 1 and 2 is constructed by extending the wall pile 106 downward from the peripheral wall 104 that also serves as a mountain retaining wall, as described above. The horizontal resistance of the foundation bottom board 102 is improved easily and at low cost.

  Next, the basic structure of the second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment, and the overlapping description is abbreviate | omitted. Further, since the configuration other than the seismic isolation pit is the same as that of the first embodiment, only the configuration of the seismic isolation pit will be described.

  As shown in FIG. 6, the base structure seismic isolation pit 200 of the second embodiment is provided with wall piles 206 at intervals. That is, the wall pile 206 is composed of a plate-like wall pile 206B provided on the long side, and an L-shaped wall pile 206A in plan view at the corners of the four corners. In other words, the discontinuous portion 202 is formed in the wall pile 206 of the peripheral wall 104. The discontinuous portion 202 is formed at one place on the peripheral wall 104S (short change) and at two places on the peripheral wall 104L (long side).

  Next, the operation of this embodiment will be described.

  When the horizontal resistance force can be sufficiently obtained without providing the wall pile 106 (see FIGS. 1 and 2) over the entire circumference like the seismic isolation pit 100 of the first embodiment, By providing the wall piles 206 at intervals, that is, by forming the discontinuous portions 202, the required horizontal resistance force can be obtained at low cost. The in-plane rigidity of the peripheral wall 104 is very high, but the out-of-plane rigidity is low. Therefore, when the aspect ratio in plan view of the seismic isolation pit is large, the horizontal resistance in the long side direction is large and the horizontal resistance in the short side direction is small. Therefore, the horizontal resistance force required at low cost can be obtained by forming a discontinuous part largely in the direction with a surplus power.

  Next, the basic structure of the third embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment, and the overlapping description is abbreviate | omitted. Further, since the configuration other than the seismic isolation pit is the same as that of the first embodiment, only the configuration of the seismic isolation pit will be described.

  As shown in FIG. 7, the base-isolated pit 300 of the third embodiment is formed with a protruding wall 302 that protrudes outward from the peripheral wall 104L having a long side. The protruding wall 302 has a plate shape whose longitudinal direction is the vertical direction, and is orthogonal to the peripheral wall 104 (T-shaped).

  In this embodiment, the protruding wall 302 protrudes from the entire region extending from the upper end of the peripheral wall 104 including the wall pile 106 to the lower end (of the wall pile 106) (the upper end of the protruding wall 302 is the upper end of the peripheral wall 104). The lower end of the protruding wall 302 is the same position as the lower end of the wall pile 106).

  Next, the operation of this embodiment will be described.

  The rigidity in the in-plane direction of the peripheral wall 104 is very high, but the rigidity in the out-of-plane direction is low. Therefore, when the aspect ratio in plan view of the seismic isolation pit is large, the horizontal resistance in the long side direction is large and the horizontal resistance in the short side direction is small. When the horizontal resistance in the short side direction is insufficient, that is, when it is necessary to increase the out-of-plane rigidity of the long peripheral wall 104L including the wall pile 106L, by forming the protruding wall 302, the protruding wall The out-of-plane rigidity of the peripheral wall 104L including the wall pile 106L is increased by the frictional resistance between 302 and the upper ground 28 (see FIG. 1), thereby improving the horizontal resistance in the short side direction (Y direction).

  In addition, in this embodiment, although the protrusion wall 302 protrudes from the whole over the lower end of the wall pile 106 from the upper end of the surrounding wall 104, it is not limited to this. For example, as in the first modification shown in FIG. 8A, the protruding wall 303 may protrude only from the wall pile 106 (the upper end of the protruding wall 303 is at the same position as the upper end of the wall pile 106). May be).

  Further, as in the second modification shown in FIG. 8B, two protruding walls 302 may be formed, or three or more may be formed as necessary.

  Next, the basic structure of the fourth embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected to the member same as 1st embodiment, and the overlapping description is abbreviate | omitted. Further, since the configuration other than the seismic isolation pit is the same as that of the first embodiment, only the configuration of the seismic isolation pit will be described.

  As shown in FIG. 9, the base-isolated pit 400 of the fourth embodiment of the present invention is formed with extending walls 402 that extend outward from the corners of the peripheral wall 104 in both directions. In other words, the extending wall 402 extends in the surface direction from the corner. Therefore, in the corner portion, the peripheral wall 104 and the extending wall 402 form a cross shape in plan view.

  In this embodiment, the extension wall 402 protrudes from the entire region extending from the upper end of the peripheral wall 104 including the wall pile 106 to the lower end (of the wall pile 106) (the upper end of the extension wall 402 is the upper end of the peripheral wall 104). The lower end of the extended wall 402 is the same position as the lower end of the wall pile 106).

  Next, the operation of this embodiment will be described.

  When it is necessary to increase the out-of-plane rigidity of the peripheral wall 104L and the peripheral wall 104S, by forming the extension wall 402, the peripheral wall including the wall pile 106 due to the frictional resistance between the extension wall 402 and the upper layer ground 28 (see FIG. 1). The out-of-plane rigidity of 104 increases, thereby improving the horizontal resistance.

  In the present embodiment, the extending wall 402 protrudes from the entire region extending from the upper end of the peripheral wall 104 to the lower end of the wall pile 106, but is not limited thereto. For example, as in the first modification shown in FIG. 10A, the extension wall 403 may protrude only from the wall pile 106 (the upper end of the extension wall 403 may be the same position as the upper end of the wall pile 106). Good). Moreover, it is good also as a structure which provided the protrusion wall 302 like the 2nd modification shown in FIG.10 (B) (It is good also as a structure which provided both the extension wall 402 and the protrusion wall 402).

  In addition, this invention is not limited to the said embodiment.

  For example, in the above-described embodiment, the peripheral wall 104 and the side surface 102A of the foundation bottom plate 102 are joined, and the peripheral wall 104 and the foundation bottom plate 102 are structurally integrated. However, the present invention is not limited to this. The peripheral wall 104 and the side surface 102A of the foundation bottom 102 need not be joined.

  Moreover, although the reinforcement of the foundation bottom board 102 at the time of performing seismic isolation repair of the existing structure 16 was demonstrated, it is not limited to this. The present invention can also be applied to a new construction.

  Moreover, in the said embodiment, although the seismic isolation pit was made into planar view substantially rectangular shape, it is not limited to this. For example, the shape according to the external shape of the structure may be sufficient.

  Moreover, in the said embodiment, although the ground recessed part 50 was formed by excavating the upper-layer ground 28, it is not limited to this. For example, the ground recess 50 may be formed by forming (filling) the first layer 22 and the second layer 24 on the third layer 26.

It is a longitudinal section showing the basic structure of a first embodiment of the present invention typically. (A) which shows the seismic isolation pit of the basic structure of 1st embodiment is a perspective view, (B) is a top view. It is a longitudinal cross-sectional view which shows typically the foundation structure using the seismic isolation pit to which this invention is not applied. FIG. 4 is a longitudinal sectional view showing a configuration in which a new pile is driven directly under a structure in the foundation structure of FIG. 3. FIG. 4 is a longitudinal sectional view showing a configuration in which a new pile is added outside the structure in the foundation structure of FIG. 3. (A) which shows the seismic isolation pit of the foundation structure of 2nd embodiment is a perspective view, (B) is a top view. (A) which shows the seismic isolation pit of the foundation structure of 3rd embodiment is a perspective view, (B) is a top view. (A) is a perspective view which shows the 1st modification of the base-isolation pit of 3rd embodiment, (B) is a perspective view which shows the 2nd modification of the base-isolation pit of 3rd embodiment. FIG. (A) which shows the seismic isolation pit of the foundation structure of 4th embodiment is a perspective view, (B) is a top view. (A) is a perspective view which shows the 1st modification of the seismic isolation pit of the foundation structure of 4th embodiment, (B) is the perspective view which shows the 2nd modification of the seismic isolation pit of the foundation structure of 4th embodiment. FIG.

Explanation of symbols

10 Foundation structure 16 Structure 28 Upper ground (ground)
50 ground recess 100 base isolation pit 102 foundation bottom 104 peripheral wall 106 wall pile 200 base isolation pit 202 discontinuity 206 wall pile 300 base isolation pit 302 projecting wall 303 projecting wall 400 base isolation pit 402 extension wall 403 extension wall

Claims (4)

Provided in the bottom of ground recesses, and foundation bottom panel for supporting a structure, a peripheral wall serving as a mountain Tomekabe before Symbol ground recess co If surround the foundation bottom plate, a seismic isolation pit but which is structurally integrated ,
And Kabekui formed by the peripheral wall of the seismic isolation pits are extending below the lower surface of the base bottom panel,
Basic structure characterized by comprising. The foundation structure according to claim 1, wherein the wall piles are provided at intervals . The foundation structure according to claim 1 or 2, wherein a projecting wall projecting outward is formed on the peripheral wall . The peripheral wall has a substantially rectangular shape in plan view,
The extending wall that extends outward in both directions from the corner is formed on the peripheral wall so that the corner of the peripheral wall has a cross shape in plan view with the peripheral wall. The foundation structure according to any one of claims 1 to 3.

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