JP3196470U - Seismic isolation structure - Google Patents

Abstract

An object of the present invention is to provide a seismic isolation structure for a structure that absorbs seismic vibration with a simple structure while using an inexpensive sand layer. A seismic isolation structure 10 is provided with a box-shaped partition wall 30 having a bottom wall portion and a side wall portion and opened upward in a recess 20 formed by bending a ground G. Then, the sand layer 40 is disposed in the partition wall 30, and the structure foundation 60 is placed on the sand layer 40. A part of the sheet layer 50 is formed by disposing a sheet layer 50 formed with a drain hole 31a in the bottom wall portion and formed of a waterproof synthetic resin so as to cover the upper surface of the sand layer 40. Is disposed between the base 60 of the structure. [Selection] Figure 1

Description

  The present invention relates to a seismic isolation structure for a structure that can handle earthquake vibration.

  There exists a thing described in patent document 1 as an uneven settlement countermeasure basic structure of a structure using a layer of sand. According to this, a concrete base plate with a U-shaped cross section is provided in a foundation embedded recess excavated in the ground, a sand layer is provided in the bottom plate, and a foundation such as a cloth foundation is partially embedded in the sand layer. It was provided.

  When uneven settlement occurred, sand around the foundation part with less settlement was fluidized by stirring it with a vibrator to artificially sink the foundation part to return the foundation level of the entire building to a uniform level.

  In addition, in the seismic isolation structure of a wooden building described in Patent Document 2, a concrete portion is disposed on a crushed stone and a crushed crushed stone laid on the excavation ground of a construction site, and through a peripheral dog-running soil concrete portion. Tightly tied to the ground. Between the solid foundation of the reinforced concrete structure that is formed on the discarded concrete section and is fitted and supported in a frame form by the dog-running soil concrete section, horizontal sliding fine movement of the solid foundation is performed on the discarded concrete section. At least one or more slide intermediate laminated parts in which a moisture-proof poly film and a sliding member (sand, pulverized talc, etc.) are laminated, and one or a plurality of outer wall material layer parts are provided on the uppermost part. Was configured.

Japanese Patent Laid-Open No. 08-209720 JP 09-242383 A

  However, the structure for countermeasures against uneven settlement of the structure of Patent Document 1 does not disclose anything about the seismic isolation for the vibration of the earthquake caused by the sand layer. If it is going to be applied as a seismic isolation structure, the fabric foundation is formed in a frame shape in a plan view, connecting the outer periphery of the structural body and the part where gravity is applied, and the bottom of the U-shaped cross section concrete is It is arranged only in the periphery. Since the foundation is partially embedded in the sand layer, there is a risk that when the foundation sinks due to the vibration of the earthquake, it touches the bottom of the bottom plate and directly transmits the vibration of the earthquake to the structure.

  Moreover, the seismic isolation structure of the wooden building of patent document 2 must provide a discarded concrete part, a slide intermediate | middle laminated part, and an outer wall material layer part between an excavation ground and a solid foundation, and makes it a simpler structure. It was hoped that.

  The present invention provides a seismic isolation structure for a structure that absorbs seismic vibrations with a simple configuration while using an inexpensive sand layer.

  In the present invention, a box-shaped partition with an open top is disposed in a recess formed by bending the ground, and a layer of sand is disposed in the partition so that the foundation of the structure is sand. The portion facing the sand layer of the foundation of the structure is formed in a flat plate shape so as to be placed on the layer and not to contact the partition wall.

  As a result, the vibration caused by the earthquake causes the sand friction to disengage and the sand grains slip off, filling the gaps between the sand grains and the air in the gaps to escape, thereby absorbing the seismic force. It is possible to provide a seismic isolation structure that absorbs earthquake vibration with a simple configuration while using a layer of sand.

  In addition, a clearance is provided so that the foundation of the structure does not contact the partition wall, and in particular, the portion of the foundation of the structure that faces the sand layer is formed in a flat plate shape and placed on the sand layer, so that the structure is affected by earthquake vibration. Even when the foundation of the sunk sinks, it can be prevented from coming into contact with the bulkhead, and can be prevented from receiving earthquake vibrations from the bulkhead.

  Furthermore, since a layer of sand is disposed in the box-shaped partition wall, the movement of the sand is restricted within the partition wall, and the amount of sand is prevented from being partially reduced due to the outflow of sand, etc. It can suppress that the foundation of an object inclines.

  Further, a waterproof sheet layer may be disposed between the sand layer and the foundation of the structure, and a drain hole may be formed in the bottom wall portion of the partition wall. The sheet layer prevents rainwater from entering the sand layer, and even if rainwater enters the sand layer, the rainwater etc. escapes from the drain holes, preventing liquefaction during an earthquake. be able to.

  According to the present invention, it is possible to absorb earthquake vibration with a simple configuration while using an inexpensive sand layer.

It is sectional drawing of the seismic isolation structure of one Embodiment in this invention. It is a schematic plan view of the seismic isolation structure of one embodiment in the present invention.

  An embodiment of the seismic isolation structure according to the present invention will be described with reference to the drawings. In the following description, the top and bottom in FIG.

  In general, the seismic isolation structure 10 is provided with a box-shaped partition wall 30 opened upward in a recess 20 formed by bending the ground G, and a sand layer is formed in the partition wall 30. 40 is provided, and the foundation 60 of the structure is placed on the sand layer 40.

  The recess 20 is formed by bending the ground G larger than the outer shape of the foundation 60 of the structure in plan view. In this embodiment, 420 mm is dug down from the reference plane GL.

  The partition wall 30 is made of concrete in which reinforcing bars formed of tensile steel are embedded, and has a bottom wall portion 31 and a side wall portion 32 extending upward from the outer peripheral edge of the bottom wall portion 31, and has a box shape with the top opened. Is formed. A drain hole 31 a is formed in the bottom wall portion 31.

  In this embodiment, the water drain hole 31a is provided at a location of 50 mm in diameter per 3 square meters. The thickness of the bottom wall part 31 and the side wall part 32 is set to 120 mm. The distance from the upper end of the side wall part 32 to the upper surface 31b of the bottom wall part 31 is set to 300 mm.

  A lid member 33 is disposed so as to cover the drain hole 31a from above. The lid member 33 is made of a non-woven fabric having water permeability and having a strength capable of preventing the sand from flowing out from the drain hole 31a.

  River sand is used for the sand layer 40, and in this embodiment, the sand layer 40 is filled up to a position of 150 mm from the upper surface 31 b of the bottom wall portion 31.

  In this embodiment, river sand is very coarse sand having a particle diameter of 2 to 1 mm, coarse sand having a particle diameter of 1/2 mm, medium sand having a particle diameter of 1/2 mm to 1/4 mm, a particle diameter of 4 The mixture is a mixture of 1/8 mm to 1/8 mm fine sand and 1/8 mm to 1/16 mm extra fine sand.

  The sheet layer 50 is made of waterproof synthetic resin, and is disposed so as to cover the upper surface of the sand layer 40, and a part thereof is disposed between the foundation 60 of the structure. Yes. In the present embodiment, a vinyl chloride sheet is used.

  The foundation 60 of the structure is made of concrete in which reinforcing bars formed of tensile steel are embedded. In this embodiment, a solid foundation is used, and the lower wall portion 60a (the portion facing the sand layer in the claims) is used. It is formed in a flat plate shape. The lower wall portion 60 a of the foundation 60 of the structure is placed on the upper surface of the sand layer 40 through the sheet layer 50 and is disposed so as not to contact the partition wall 30.

  The crushed stone layer 70 is formed by laying stones having a particle diameter larger than that of sand in a portion surrounded by the foundation 60 of the structure, the partition walls 30 and the sheet layer 50 in a longitudinal sectional view. In this embodiment, crushed stone having a diameter of about 25 mm is used.

  The construction method of the seismic isolation structure 10 is demonstrated. First, the concave portion 20 is formed by bending the ground G larger than the outer shape of the structure in plan view. A partition wall 30 made of concrete in which a reinforcing bar formed of tensile steel is embedded in the recess 20 is laid in a box shape having a bottom wall portion 31 and a side wall portion 32 and open upward. One drainage hole 31a is provided in the bottom wall portion 31 of the partition wall 30 per 3 square meters. The lid member 33 is disposed so as to cover the drain hole 31a from above. River sand is thrown into the partition wall 30 to form a sand layer 40. The sheet layer 50 is formed by disposing a waterproof synthetic resin on the upper side of the sand layer 40. The base 60 of the structure is placed on the lower wall portion 60a on the upper side of the sheet layer 50 and arranged so as not to contact the partition wall 30, and the base 60 of the structure, the partition 30, and the sheet layer 50 are viewed in a longitudinal sectional view. The crushed stone layer 70 is formed by laying stones having a particle diameter larger than that of sand in the enclosed portion, and the seismic isolation structure 10 is completed.

  Even if a ground subsidence of 1 to 3 centimeters occurs due to the vibration of the earthquake, the subsidence is corrected by removing the sand in the partition wall 30 on the side where the foundation 60 of the structure is tilted and becomes high with a vacuum pump. Can do.

  If ground subsidence of 3 centimeters or more occurs due to earthquake vibration, it is possible to correct the subsidence by removing the sand in the partition wall 30 that has been tilted and lowered and jacking up with an air jack. It becomes.

  The applicant conducted a collapse experiment in which a structure using the seismic isolation structure 10 at a scale of 1/10 was given a vibration force of seismic intensity 7,800 gal. Even if a vibration force was applied for 18 seconds, it did not collapse. As a comparative example, an ordinary structure having a scale of 1/10 was not able to withstand vibration force in 8 seconds and collapsed.

  In the seismic isolation structure 10, a box-shaped partition wall 30 opened upward is disposed in a recess 20 formed by bending the ground G, and a sand layer 40 is disposed in the partition wall 30. The base 60 of the structure is placed on the sand layer 40 and arranged so as not to contact the partition wall 30, and the lower wall portion 60a of the base 60 of the structure is formed in a flat plate shape.

  As a result, the vibration caused by the earthquake causes the sand friction to disengage and the sand grains slip off, filling the gaps between the sand grains and the air in the gaps to escape, thereby absorbing the seismic force. It is possible to provide the seismic isolation structure 10 that absorbs the vibration of the earthquake with a simple configuration while using the sand layer 40.

  Further, a clearance is provided so that the structure foundation 60 does not contact the partition wall 30, and in particular, a portion of the structure foundation 60 that faces the sand layer 40 is formed in a flat plate shape and placed on the sand layer 40. Even when the foundation 60 of the structure sinks due to vibration, it can be prevented from coming into contact with the partition wall 30 and can be prevented from receiving earthquake vibration from the partition wall 30.

  Further, since the sand layer 40 is disposed in the box-shaped partition wall 30, the movement of the sand is limited in the partition wall 30, and the amount of sand is prevented from being partially reduced due to the outflow of sand or the like. Therefore, it can suppress that the foundation 60 of a structure inclines.

  Further, by providing a waterproof sheet layer 50 between the sand layer 40 and the foundation 60 of the structure, and forming a drain hole 31 a in the bottom wall portion 31 of the partition wall 30. The sheet layer 50 prevents rainwater and the like from entering the sand layer 40, and even if rainwater or the like enters the sand layer 40, the rainwater etc. escapes from the drain hole 31a and is liquid when an earthquake occurs. Can be prevented.

  Further, in the seismic isolation method for a structure, a box-shaped partition wall 30 opened upward is disposed in a recess 20 formed by bending the ground G, and a sand layer 40 is disposed in the partition wall 30. The base 60 of the structure in which the lower wall portion 60a is formed in a flat plate shape is placed on the sand layer 40 and arranged so as not to contact the partition wall 30.

  The shape of the partition wall 30 can be formed in a box shape corresponding to the shape of the structure in plan view.

  The sand layer 40 may be sea sand or mountain sand.

DESCRIPTION OF SYMBOLS 10 Seismic isolation structure 20 Recessed part 30 Partition 31 Bottom wall part 31a Drain hole 31b Upper surface 32 Side wall part 33 Cover member 40 Sand layer 50 Sheet layer 60 Foundation 60a Lower wall part 70 Crushed stone layer G Ground GL Reference surface

Claims (2)

In the recess formed by bending the ground, a box-shaped partition with an open top is arranged,
In the partition, a layer of sand is disposed,
The foundation of the structure is placed on the sand layer and arranged so as not to contact the partition,
A base isolation structure for a structure, wherein a portion of the foundation of the structure facing the sand layer is formed in a flat plate shape. Between the sand layer and the foundation of the structure, a waterproof sheet layer is disposed,
2. The seismic isolation structure for a structure according to claim 1, wherein a drain hole is formed in a bottom wall portion of the partition wall.