JP2011157775A - Base isolating foundation structure for building - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base isolating foundation structure for buildings, which exerts an appropriate vibration damping action relative to lightweight buildings such as houses, prevents the oscillation of buildings in strong winds, avoids resonance of buildings in earthquakes, and prevents low frequency oscillation damages to residents. <P>SOLUTION: The base isolating foundation structure 1 for buildings includes a recess portion 4 formed in the foundation 2 by excavating the foundation from an existing ground level 3, a plurality of gravel bags 5 accommodating therein gravel-like materials 5y respectively and arranged in the recess portion 4, and a base 7 of a building 6 supported on the gravel bags 5. When the foundation 2 is vibrated, the gravel-like materials 5y in the gravel bags 5 move therein, causing a force pulling the surface of the gravel bags 5 to partially consume the vibration force to be transferred to the building 6. The vibration passing through the gravel bags 5 is converted into vibration shorter in cycle, avoiding the resonance of building 6 and the low frequency oscillation damage to the residents. The base 7 is supported on the gravel bags 5 over its broad areas, stably supporting the building 6 even in strong winds. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a seismic isolation base structure that weakens ground vibrations and transmits it to a building.

  As a seismic isolation structure of a building, one using a damping means such as a seismic isolation damper is known (see Patent Documents 1 and 2). This type of seismic isolation structure has, for example, a damping means such as a seismic isolation damper interposed between a part near the ground at the bottom of the building and a part above it. The vibration transmitted to the building is absorbed by the damping function of the damping means such as the seismic isolation damper.

  As another seismic isolation structure for another building, one using a sliding bearing such as a rocking ball (see Patent Documents 3 and 4) is known. In this type of seismic isolation structure, for example, a saucer whose upper part is recessed in a substantially hemispherical shape is installed on the ground side, and a support column extending downward from the foundation beam of the building is inserted into the support plate and provided at the lower end of the support column. Ball bearings support the building's load on the tray, and when the ground vibrates, the ball bearing rolls or slides in the tray and the struts move in the tray to reduce vibration transmitted to the building. .

Japanese Patent Laid-Open No. 11-270180 JP 2004-190424 A JP 2006-328655 A JP 2008-280818 A

  By the way, a seismic isolation structure using a damping means such as a seismic isolation damper requires a certain amount of weight in a building in order to obtain an appropriate vibration damping effect, and is effective for lightweight buildings such as houses. There is a problem that it is difficult to expect. On the other hand, the seismic isolation structure using a sliding bearing such as a rocking ball has a problem that the control of the shaking due to the wind damage is necessary because the building is shaken by the fluctuation of the wind force when the wind is strong.

  In addition, the seismic isolation structure using these damping means and sliding bearings is only to attenuate or weaken the vibration of the ground and transmit it to the building, and actively change the period and wavelength of the ground vibration to the building. It is not something to convey. For this reason, depending on the geological composition of the ground and the depth from the ground surface to the rock plate, the dominant period of the ground at the time of the earthquake may coincide with the natural period of the building, in which case resonance occurs and the building Great damage will occur.

  Furthermore, the seismic isolation structure using these damping means and sliding bearings can transmit to the building not only the vibration at the time of earthquake but also the vibration caused by surrounding traffic (traffic vibration) by attenuating or weakening the vibration. Although it can be done, it does not actively change the frequency and wavelength of the vibration as described above and transmit it to the building, so if the frequency of the vibration is long, it may cause a low-frequency vibration disturbance to the resident depending on the frequency. There is also.

  The purpose of the present invention, which was created in consideration of the above circumstances, is able to exert an appropriate vibration damping action even for lightweight buildings such as houses, so that the buildings do not shake during strong winds and avoid resonance of the buildings during earthquakes An object of the present invention is to provide a seismic isolation base structure for a building that can prevent a low-frequency vibration failure.

  In order to achieve the above object, the seismic isolation foundation for a building according to the present invention has a recess formed by digging into the ground from an existing ground level, and a plurality of such recesses are laid, each containing gravel-like substances. A gravel bag and a building foundation supported by the gravel bag.

  A sliding sheet may be interposed between the gravel bag and the lower end of the foundation to allow the foundation to move in a horizontal direction with respect to the gravel bag during ground vibration.

  As a suitable representative example of the gravel-like substance, a lightweight structural aggregate can be mentioned.

  The gravel bags are a plurality of lower gravel bags arranged below the existing ground level, and upper gravel bags stacked above the existing ground level by being stacked on top of the lower gravel bags. The foundation is formed in a disc shape so as to cover the foundation rising part supported by the lower gravel bag on which the upper gravel bag is not stacked, and the upper part of the upper gravel bag. A foundation pressure platen supported by an upper gravel bag and connected to the foundation rising part, and the sliding sheet is provided between the lower gravel bag and the lower end of the foundation rising part, and the lower gravel bag. It may be interposed between the upper gravel bags.

  In order to restrain a plurality of the lower gravel bags, a restraining bag for accommodating the plurality of lower gravel bags may be further provided.

  A heat input port that is provided through the upper and lower sides of the basic pressure-resistant panel part and that heats the air heated by solar heat downward from above the basic pressure-resistant plate part and stores the heat in the upper gravel bag, and the basic pressure resistance A heat output port for supplying air warmed by the heat stored in the upper gravel bag to the upper chamber, provided on the board portion so as to penetrate the upper and lower sides away from the heat input port; Also good.

  The upper gravel bag has air permeability, and further comprises a ventilation guide sheet comprising a lower surface sheet portion in contact with the lower surface of the upper gravel bag and a side sheet portion extending upward from an edge of the lower surface sheet portion, Between the ventilation guide sheet and the basic pressure-resistant portion, a ventilation passage serving as an air passage from the heat input port through the upper gravel bag to the heat output port may be formed.

  In order to transmit the heat stored in the upper gravel bag to the room through the basic pressure-resistant board part, an indoor floor may be laid directly on the basic pressure-resistant board part.

According to the base isolation structure of a building according to the present invention, the following effects can be exhibited.
(1) When the ground vibrates, the gravel-like substance in the gravel bag moves in the bag, and a force for pulling the surface of the gravel bag and a force for pressing adjacent gravel bags are generated. As a result, part of the vibration force of the ground is converted into a force that pulls the surface of the gravel bag and a force that presses adjacent gravel bags. Therefore, the vibration of the ground is weakened and transmitted to the building, and an appropriate vibration damping action can be exhibited even for a lightweight building such as a house.
(2) Since the foundation of the building is supported by the gravel bag, the foundation can be supported more stably than the conventional seismic isolation structure in which the foundation is supported using a sliding bearing such as a rocking ball. Therefore, the building does not sway in strong wind unlike the seismic isolation structure using sliding bearings such as rocking balls.
(3) When the vibration of the ground passes through the gravel bag and is transmitted to the building, the period of vibration is significantly reduced, that is, the wavelength is shortened and transmitted to the building. As a result, a vibration having a period significantly smaller than the natural period of the building is transmitted to the building. Therefore, the resonance of the building can be avoided at the time of the earthquake, and at the same time, the occupant's low frequency vibration disturbance can be prevented.
(4) Since the ground was dug down from the existing ground level to form recesses and gravel bags were laid there, the earth and sand removed when forming the recesses were replaced with gravel-like substances in the gravel bags, improving the ground Has been. Therefore, even if the ground is soft ground, ground subsidence can be suppressed.

It is explanatory drawing which shows the outline of the base isolation structure of the building which concerns on one Embodiment of this invention, and is a side sectional view of a ground, a gravel bag, a foundation, a sliding sheet, and a building. It is the elements on larger scale of FIG. It is explanatory drawing which represented typically the upper gravel bag of FIG. 2, a lower gravel bag, a sliding sheet | seat, etc. FIG. It is explanatory drawing which represented typically the seismic wave propagated from the ground to a building at the time of an earthquake. It is explanatory drawing which shows a mode that the force of the diagonal direction at the time of an earthquake was divided into the force of a horizontal direction, and the force of a perpendicular direction. It is explanatory drawing which shows a mode that the force of a horizontal direction and the force of a perpendicular direction act on a gravel bag. It is explanatory drawing which shows a mode that the gravel in a gravel bag moves in a bag and pulls the surface of a gravel bag when the force of a horizontal direction and the force of a perpendicular direction act on a gravel bag, (a) is gravel A state where the bag is compressed from the horizontal direction, (b) shows a state where the gravel bag is compressed from the vertical direction. It is explanatory drawing when what accommodated the several gravel bag in the restraint bag was compressed from the horizontal direction.

  Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, the building base isolation structure 1 according to this embodiment includes a recess 4 formed by digging in the ground 2 from an existing ground level 3, and a plurality of recesses 4 laid in the interior. The gravel bag 5 in which the gravel-like substance is accommodated, and the foundation 7 of the building 6 supported by the gravel bag 5 are provided. Further, between the gravel bag 5 and the lower end of the foundation 7, a sliding sheet 8 is interposed that allows the foundation 7 to move in the horizontal direction with respect to the gravel bag 5 at the lower end when the ground 2 vibrates. .

  The concave portion 4 is formed by rooting the ground 2 from the surface layer to a good ground surface by a predetermined depth (for example, about 20 to 50 cm). Since the gravel bags 5 are laid in the concave portion 4 in place of the earth and sand removed therefrom, the earth and sand removed when forming the concave portion 4 can also be considered as the earth and sand removed for ground improvement. Here, the thickness of the earth-and-sand replacement layer, that is, the depth of the recess 4 resonates when the period of vibration transmitted from the ground 2 to the building 6 through the gravel bag 5 matches the natural period of the building 6 as will be described later. In order to avoid this, the depth is set to a sufficiently small depth. Since this depth varies depending on the loading amount of the building 6 and the geology of the ground 2, it needs to be examined according to the loading amount and the geology, but it is sufficient if it is approximately 30 to 40 cm.

  In the case where the ground 2 is exposed with rocks on the ground surface, the dominant period representing the characteristics of the ground 2's shaking is approximately 0.1 seconds (about 10 Hz), and volcanic ash like the Kanto Loam Formation. In the case of the ground 2 of the sedimentary ground, the dominant period is approximately 0.4 seconds (about 2.5 Hz), and in the case of the ground 2 that reclaims the coast or the ground 2 that reclaims rice fields and swamps, the dominant period is approximately 1 0.0 second to 0.8 second (about 1 Hz to 1.25 Hz). On the other hand, for building 6, the natural period of Japanese wooden buildings is approximately 0.4 seconds (about 2.5 Hz) in the case of old Japanese style wooden houses, and is generally 0 in the case of wooden houses constructed in recent years. 3 seconds to 0.35 seconds (about 3.3 Hz to 2.9 Hz). In this way, the dominant period of the ground 2 and the natural period of the building 6 are within a range of 0.1 seconds to 1.0 seconds and are extremely close. Therefore, if the gravel bag 5 does not exist, the ground 2 The building 6 may resonate when vibrated.

  Therefore, in this embodiment, the gravel bag 5 is laid between the ground 2 and the foundation 7 by laying the gravel bag 5 in the recess 4 formed in the ground 2 and supporting the foundation 7 of the building 6 on the gravel bag 5. Is interposed. As will be described later, the gravel bag 5 exhibits a function of greatly shortening the period of vibration transmitted from the ground 2 to the building 6.

  As shown in FIG. 2, the gravel bag 5 includes a bag body 5x made of cloth, nonwoven fabric, fine nets, and the like, and a gravel-like substance 5y accommodated in the bag body 5x. The concept of the gravel-like substance 5y here includes gravel having a particle size of several tens of millimeters, sand having a particle size of millimeters, or a mixture of sand and gravel, and relatively light sand and gravel. preferable. Moreover, it is preferable to use a lightweight structural aggregate for the gravel-like substance 5y. As the lightweight structural aggregate, for example, an artificial lightweight aggregate called Mesalite (registered trademark, MESALITE: Mitsui Expanded Shale Light-Weight Aggregate) sold by Nippon Mesalite Industry Co., Ltd. is used.

  When the gravel-like substance 5y is sand, the natural period of the sand is extremely small 0.025 seconds (about 40 Hz), and even in the case of gravel with a particle size of about 35 mm, the natural period is 0.125 seconds to 0.077. Second (about 8 Hz to 13 Hz). By supporting the foundation 7 of the building 6 on the gravel bag 5 in which the gravel-like substance 5y such as sand, gravel, structural lightweight aggregate or the like is accommodated, the foundation that substantially supports the building 6 becomes the gravel bag 5. Since the natural period of the gravel-like substance 5y in the gravel bag 5 and the natural period of the building 6 are significantly different, resonance can be avoided.

  That is, as shown in FIG. 4, when the vibration of the ground 2 passes through the gravel bag 5 and is transmitted to the building 6, the period of vibration is significantly reduced, that is, the wavelength is shortened and transmitted to the building 6. During an actual earthquake, not only the seismic wave A that propagates horizontally from the epicenter direction and reaches the building 6, but also the seismic wave B that propagates diagonally from the bottom to the building 6 and the bedrock G directly below the building 6 The seismic wave C propagating to 6 or the seismic wave D propagating to the building 6 after being reflected by the rock G once propagates to the building 6 while interfering with each other. The seismic waves in each direction pass through the gravel bag 5. As a result, the cycle is significantly smaller than the natural cycle of the building 6 and is transmitted to the building 6. Thereby, not only when the building 6 is a wooden house, but also when the building 6 is a concrete house, resonance can be avoided. Moreover, since the vibration transmitted to the building 6 becomes a high frequency, it is possible to prevent a resident's low frequency vibration disturbance.

  As shown in FIGS. 1 and 2, the gravel bag 5 laid in the recess 4 includes a plurality of lower gravel bags 5 a arranged below the existing ground level 3 and a part of these lower gravel bags 5 a. There are two types: an upper gravel bag 5b that is stacked on top of the removed ground level 3 and placed above the ground level 3. Specifically, the lower gravel bags 5a are laid out flat on the entire bottom surface of the recess 4 and stacked in two upper and lower stages. On the other hand, the upper gravel bag 5b is supported on the lower gravel bag 5a excluding the lower gravel bag 5a at the edge of the plurality of lower gravel bags 5a laid out in a plane, and is divided into two upper and lower steps. Are stacked. Note that at least one of the lower gravel bag 5a and the upper gravel bag 5b may be one or three or more.

  The lower gravel bag 5a is accommodated in the restraining bag 9, as shown in FIGS. FIG. 3 is a schematic diagram, and differs from FIG. 2 in the number of lower gravel bags 5a accommodated in the restraining bag 9.

  A procedure for accommodating the lower gravel bag 5a in the restraining bag 9 will be described.

  First, a bottom side sheet 9a that constitutes the bottom and sides of the restraint bag 9 is laid in the recess 4, and a lower gravel bag 5a is laid on the top, and the gap between adjacent bags is from the one in the bag 5a. Fill with small gravel-like particles (pebbles, sand and structural lightweight aggregates) and press to compact. In the same manner, the second lower gravel bags 5a are laid out on top of each other, and small gravel-like particles are filled in the gaps between adjacent bags, and are pressed and compacted.

  Here, the size of the bag body 5x of the lower gravel bag 5a and the amount of the gravel-like substance 5y filled therein are adjusted so that the upper surface of the second lower gravel bag 5a matches the height of the existing ground level 3. deep. The upper sheet 9b constituting the upper part of the restraining bag 9 is hung on the upper surface of the second lower gravel bag 5a, and the upper sheet 9b is tied to or tied to the bottom side sheet 9a. Thereby, the upper sheet 9b and the bottom side sheet 9a become the restraining bag 9.

  The restraining bag 9 preferably has water permeability (for example, cloth, nonwoven fabric, mesh, etc.). Otherwise, when rainwater enters the inside of the restraint bag 9, the water is accumulated in the restraint bag 9, and a water pool that is a source of moisture exists below the foundation 7. In addition, the restraint bag 9 is not limited to the one in which all the lower gravel bags 5a are accommodated in the single restraint bag 9 as shown in FIG. 2, and several lower gravel bags 5a are separated by the same procedure. You may make it accommodate in the accommodation bag 9 (refer FIG. 3).

  As shown in FIGS. 2 and 3, the sliding sheet 8 is placed on the upper sheet 9 b of the restraining bag 9 according to the existing ground level 3. The sliding sheet 8 exhibits a function of absorbing vibrations when the foundation 7 slides in the horizontal direction when the roll of the earthquake is large. The sliding sheet 8 is made of a material that is easy to slide on the base 7 and is not easily damaged even if the base 7 slides, such as a hard plastic sheet. The size of the sliding sheet 8 is set larger than that of the recess 4, and the edge portion of the sliding sheet 8 protrudes from the recess 4 and is placed on the existing ground level 3. Thereby, the foundation 7 which slides on the sliding sheet 8 at the time of an earthquake is combined with the upper surface of the second-stage lower gravel bag 5a corresponding to the height of the existing ground level 3, and only the inside of the recess 4 In addition, it can slide out of the recess 4. Therefore, large rolls during a large earthquake can be reliably absorbed.

  As shown in FIG. 2, the foundation 7 includes a foundation rising portion 7a supported by a lower gravel bag 5a (lower gravel bag 5a disposed along the edge of the recess 4) on which the upper gravel bags 5b are not stacked. And a basic pressure-resistant board portion 7b that is formed in a disk shape so as to cover the upper part of the upper gravel bag 5b and is supported by the upper gravel bag 5b. The foundation pressure-resistant board part 7b and the foundation raising part 7a are connected, and comprise what is called a solid foundation. The foundation rising portion 7a is formed in a frame shape in plan view, and the upper gravel bag 5b is accommodated in the inside thereof with substantially no gap. The sliding sheet 8 is interposed between the lower end of the foundation rising portion 7a and the lower gravel bag 5a, and between the upper gravel bag 5b and the lower gravel bag 5a. Therefore, when the foundation 7 slides on the sliding sheet 8, the upper gravel bag 5b slides on the sliding sheet 8 integrally with the foundation 7, and the upper gravel bag 5b moves in the horizontal direction with respect to the lower gravel bag 5a. To do.

  As shown in FIG. 1, the basic pressure-resistant board portion 7 b has upper and lower heat input ports 10 for guiding the air heated by solar heat from the upper side to the lower side of the basic pressure-resistant board portion 7 b to store heat in the upper gravel bag 5 b. Is provided. As shown in FIGS. 1 and 2, the basic pressure-resistant panel 7b has a heat output port 11 for supplying air heated by heat stored in the upper gravel bag 5b into the upper chamber. It is provided so as to penetrate the top and bottom away from the hot mouth 10. In FIG. 1, one heat input port 10 is disposed in the approximate center (middle) of the basic pressure-resistant panel portion 7 b, and the heat output port 11 is located at the end of the basic pressure-resistant plate portion 7 b (side the foundation rising portion 7 a). However, the present invention is not limited to this, and two or more heat inlets 10 may be provided, and heat outlets 11 may be provided for each room on the first floor. May be.

  A system for guiding air heated by solar heat to the heat input 10 will be described.

  As shown in FIG. 1, the attic of the building 6 includes not only solar heat (which is obtained from direct sunlight, but also heat obtained from sunlight after direct sunlight has passed through solar cells or the like. The warm air storage chamber 12 for storing the warmed air is formed. The warm air storage chamber 12 and the heat input port 10 are connected by a duct 13 formed vertically from the first floor to the second floor through the second floor. A fan 14 for sending the air in the warm air storage chamber 12 to the heat input port 10 is provided in the duct 13. The fan 14 may be capable of reversing the blowing direction. Further, an opening 15 for taking indoor air into the warm air storage chamber 12 is formed in the ceiling on the second floor.

  As shown in FIGS. 1 and 2, a wall 16 of the building 6 is formed with an in-wall air passage 17 along the vertical direction. The wall 16 includes an inner wall 16a supported by a base (foundation beam) 18 installed on the foundation rising portion 7a, a heat insulating material 16b disposed on the outer side thereof, and an in-wall air passage 17 on the outer side thereof. And an outer wall 16c disposed with a gap to be formed. That is, the in-wall air passage 17 is formed between the outer wall 16c and the heat insulating material 16b. The lower end of the in-wall air passage 17 is opened to the outside at the side of the foundation rising portion 7a, and the upper end of the in-wall air passage 17 is connected to an intermediate warm air storage chamber 19 formed on the back of the eave. Further, an opening 20 for taking outside air into the intermediate warm air storage chamber 19 is formed in the eaves ceiling. The intermediate warm air storage chamber 19 at the back of the eaves and the warm air storage chamber 12 at the attic are connected by an air passage 22 in the roof formed inside the roof 21.

  According to the above configuration, when the fan 14 is driven, external air is sucked from the opening at the lower end of the in-wall air passage 17 and rises in the in-wall air passage 17 so that the outer wall 16c heated by sunlight is heated. Heated by heat, the specific gravity becomes smaller than before being warmed, and the ascending force becomes stronger, reaching the intermediate warm air storage chamber 19 on the back of the eaves. The air rises through the in-roof air passage 22 together with the air guided from the opening 20 formed in the eaves, and is heated by receiving heat from the roof 22 heated by sunlight. To the warm air storage chamber 12. The air is sucked into the duct 13 together with the air guided from the opening 15 formed in the ceiling on the second floor, pushed downward by the fan 14, and reaches the lower side of the basic pressure-resistant panel part 7 b through the heat input port 10. The upper gravel bag 5b is warmed by this air (warm air), and heat is stored in the gravel-like substance 5y.

  The heat stored in the gravel-like substance 5y of the upper gravel bag 5b warms the air below the basic pressure-resistant board part 7b. The warmed air is pushed away toward the heat output port 11 by the air flow (inertia force) generated by the fan 14, and is supplied to the room above the basic pressure-resistant panel 7b through the heat output port 11. The This achieves indoor heating. Here, as shown in FIG. 1, if the floor 23 in the first floor room is laid directly on the basic pressure-resistant panel 7 b, the heat stored in the upper gravel bag 5 b can be transferred only from the heat outlet 11. Instead, it can be transmitted to the room through the basic pressure-resistant panel 7b and the floor 23.

  In order to efficiently use the heat stored in the gravel-like material 5y of the upper gravel bag 5b, the bag body 5x of the upper gravel bag 5b has a breathable material or structure (for example, cloth, nonwoven fabric, fine net, etc.) It is preferable that As shown in FIGS. 2 and 3, a ventilation guide sheet 24 is laid under the upper gravel bag 5b, and the upper gravel bag is provided between the ventilation guide sheet 24 and the basic pressure-resistant portion 7b from the heat input port 10. You may form the ventilation path 25 (refer FIG. 1) used as the path | route of the air which passes 5b and goes to the heat output port 11. FIG. With this ventilation passage 25, the air introduced from the heat input port 10 can be accurately passed through the upper gravel bag 5b and guided to the heat output port 11, and the heat stored in the upper gravel bag 5b can be efficiently transferred to the room. Can be used for heating.

  As shown in FIGS. 2 and 3, the ventilation guide sheet 24 is extended upward along the foundation rising portion 7a from the lower surface sheet portion 24a in contact with the lower surface of the upper gravel bag 5b and the edge of the lower surface sheet portion 24a. The side sheet portion 24b is formed of a material such as vinyl or glass fiber that does not allow air to pass therethrough. As a result, the air that flows in the horizontal direction along the lower surface sheet portion 24a of the ventilation guide sheet 24 is turned upward by the side surface sheet portion 24b and rises along the foundation rising portion 7a. It is guided to the heat output port 11 arranged on the side.

  The ventilation guide sheet 24 constitutes a part of the ventilation passage 25 as described above, and also serves as a moisture-proof sheet and an ant-proof sheet. In order to enhance the ant-proofing performance, a glass fiber sheet impregnated with boric acid is used as the ventilation guide sheet 24. The ventilation guide sheet 24 also functions to restrain the plurality of upper gravel bags 5b by fixing the side sheet portions 24b to the side portions of the upper gravel bags 5b.

  As shown in FIG. 2, the ventilation guide sheet (one in which the lower surface sheet portion 24 a and the side surface sheet portion 24 b are integrated) 24 is placed on the above-described sliding sheet 8. On the guide sheet 24, the upper gravel bags 5b are laid out in one row, and gaps between adjacent bags are filled with gravel-like particles smaller than those in the bags 5b (gravels, sand, and structural lightweight aggregates), Tighten and compact. In the same manner, second-stage upper gravel bags 5b are laid out side by side, and small gravel-like particles are filled in the gaps between adjacent bags, and are compacted by pressure. And the side sheet | seat part 24b of the ventilation guide sheet 24 is turned up, and it fixes to the side part of the upper gravel bag 5b.

  Thereafter, a concrete dam plate (not shown) is disposed on the sliding sheet 8 in a frame shape in plan view so as to surround the upper gravel bag. A reinforcing bar for foundation (not shown) is placed inside the weir plate. Reinforcing bars are arranged in a portion that becomes the foundation rising portion 7a and a portion that becomes the basic pressure-resistant board portion 7b, respectively. After the bar arrangement, concrete is placed inside the dam plate, and the foundation 7 composed of the foundation rising part 7a and the foundation pressure board part 7b is constructed. In the foundation 7 constructed in this way, the upper gravel bag 5b is accommodated inside the foundation rising part 7a without any gap, the foundation pressure board 7b and the upper gravel bag 5b are in close contact, and the load of the foundation pressure board part 7b is higher. Supported by the gravel bag 5b, the load of the foundation rising portion 7a is supported by the lower gravel bag 5a.

  Finally, the earth is filled outside the foundation rising portion 7 a so as to cover the sliding sheet 8, and a new ground level (new ground level) 26 is obtained. On the seismic isolation foundation 1 thus constructed, the above-described building 6 is constructed.

  The operation of the base isolation structure 1 according to this embodiment will be described.

  When the ground 2 vibrates, the gravel-like substance 5y in the gravel bags (lower gravel bag 5a, upper gravel bag 5b) 5 moves in each bag 5x and pulls the surface of the bag 5x or adjacent gravel bags. The force which presses 5 mutually arises. As a result, part of the vibration force of the ground 2 is converted into a force that pulls the surface (fiber) of the bag body 5x of the gravel bag 5 or a force that presses the adjacent gravel bags 5 together, and the vibration of the ground 2 is weakened and the building It is transmitted to 6. Therefore, this base isolation structure 1 always exhibits an accurate vibration damping action regardless of the weight of the building 6, and also exhibits an appropriate vibration damping action even for a light building such as a house.

  For example, as shown in FIG. 5, the seismic force F propagating obliquely upward in the ground 2 to the gravel bag 5 is considered as being decomposed into a horizontal X-direction component x and a vertical Y-direction component y. be able to. FIG. 6 shows a state in which an X-direction component x is added to the gravel bag 5 from the left and right, and a Y-direction component y added to the gravel bag 5 from below acts to balance the load W of the building 6.

  As shown in FIG. 7A, when the X-direction component x is added to the gravel bag 5 from the left and right, and the gravel bag 5 is compressed from the horizontal direction, the gravel-like substance 5y in the bag body 5x is contained in the bag body 5x. To move the surface of the bag 5x. Further, as shown in FIG. 7B, even if the Y-direction component y is applied to the gravel bag 5 from below and the load W of the building 6 is applied from above, the gravel bag 5 is compressed from the vertical direction. The gravel-like substance 5y inside moves in the bag 5x, and the surface of the bag 5x is pulled. Thus, the vibration force transmitted to the building 6 is reduced because the vibration force of the ground 2 is consumed by the force that moves the gravel-like substance 5y of the gravel bag 5 and the force that pulls the surface of the bag body 5x.

  FIG. 8 shows the operation of the restraining bag 9 that accommodates the plurality of gravel bags 5. When the bags 5x of the individual gravel bags 5 are deformed as described with reference to FIGS. 7 (a) and 7 (b), the surface of the restraining bag 9 (fibers) is accommodated by the deformation of each bag 5x. ) Is pulled. Therefore, the vibration force of the ground 2 is consumed not only by the force pulling the surface of the bag body 5x of each gravel bag 5, but also by the force pulling the surface of the restraining bag 9 that accommodates these gravel bags 5. As a result, the force transmitted to the building 6 is further weakened.

  As shown in FIG. 8, when the X direction component x of the seismic wave is applied to the restraint bag 9 from the left and right, the X direction component x pulls the force pulling the surface of the bag body 5 x of the gravel bag 5 and the surface of the restraint bag 9. A force y1 above the Y direction and a force y2 below the Y direction are generated. The force y1 above the Y direction is offset with the resultant force Y1 of the load of the building 6 and the intrusion force during the earthquake, and the force y2 below the Y direction is offset with the thrust force of the seismic wave and the resultant force Y2 of the Y direction component. As a result, the balance in the Y direction is maintained.

  In addition, as shown in FIGS. 1 and 2, the seismic isolation base structure 1 has the lower end of the foundation rising portion 7a placed on the sliding seat 8, so that when the earthquake roll is large, The base 7 slides on the sliding sheet 8 in the horizontal direction, and it is difficult for the roll to be transmitted to the building 6. That is, the roll of the ground 2 at the time of a huge earthquake is absorbed when the foundation 7 slides on the sliding sheet 8 in the horizontal direction, and is extremely weakened and transmitted to the building 6. As a result, the building 6 can be prevented from collapsing during a huge earthquake.

  In addition, in the base isolation structure 1, the foundation 7 of the building 6 is supported by the gravel bag 5 over a wide area. Specifically, the lower end surface of the foundation rising portion 7a is supported by the lower gravel bag 5a, and the lower surface of the foundation pressure resistant board portion 7b is entirely supported by the upper gravel bag 5b. Therefore, the base 7 can be supported more stably than a conventional seismic isolation structure using a sliding bearing such as a rocking ball, and the building sways in a strong wind like a seismic isolation structure using a sliding bearing such as a rocking ball. There is nothing.

  Furthermore, as described with reference to FIG. 4, when the vibration of the ground 2 passes through the gravel bag 5 and is transmitted to the building 6, the period of vibration is significantly reduced, that is, the wavelength is shortened and transmitted to the building 6. . As a result, regardless of the dominant period of the ground 2, vibration having a period significantly smaller than the natural period of the building 6 is transmitted to the building 6. Therefore, resonance of the building 6 can be avoided at the time of an earthquake, and at the same time, a resident's low frequency vibration disturbance can be prevented.

  Further, since the recess 2 was formed by digging from the existing ground level 3 in the ground 2 and the gravel bags 5 (the lower gravel bag 5a and the upper gravel bag 5b) were arranged there, they were removed when the recess 4 was formed. The earth and sand are replaced with gravel-like substances 5y in the gravel bag 5 to improve the ground. And the foundation pressure | voltage resistant board part 7b of the foundation 7 is supported on it. Therefore, even if the ground 2 is soft ground, it is possible to suppress the settlement of the foundation 7 (ground settlement).

  The present invention is not limited to the above embodiment. For example, the restraining bag 9, the ventilation guide sheet 24, the heat input port 10, the heat output port 11, and the sliding sheet 8 can be omitted as appropriate for any one or a plurality of them.

DESCRIPTION OF SYMBOLS 1 Seismic isolation foundation 2 Ground 3 Existing ground level 4 Recess 5 Gravel bag 5a Lower gravel bag 5b Upper gravel bag 5x Bag body 5y Gravel material 6 Building 7 Foundation 7a Foundation rising part 7b Foundation pressure board part 8 Sliding sheet 9 Restraint Bag 10 Heat input port 11 Heat output port 23 Floor 24 Ventilation guide sheet 24a Lower surface sheet portion 24b Side sheet portion 25 Ventilation passage

Claims (8)

A recess formed by digging into the ground from the existing ground level;
A plurality of gravel bags laid in the recesses, each containing a gravel-like substance,
The foundation of the building supported by the gravel bag;
A base-isolated base structure of a building characterized by comprising Between the gravel bag and the lower end of the foundation, interposed a sliding sheet that allows the foundation to move in the horizontal direction with respect to the gravel bag during vibration of the ground,
The base isolation structure for a building according to claim 1. For the gravel-like substance, a structural lightweight aggregate was used,
The base isolation structure of a building according to claim 1 or 2. The gravel bags are a plurality of lower gravel bags arranged below the existing ground level, and upper gravel bags stacked above the existing ground level by being stacked on top of the lower gravel bags. It consists of two kinds of
The foundation is supported by the upper gravel bag formed in a disk shape so as to cover the upper part of the upper gravel bag, and a foundation rising portion supported by the lower gravel bag on which the upper gravel bag is not stacked. A foundation pressure-resistant panel connected to the foundation start-up part;
The sliding sheet is interposed between the lower gravel bag and the lower end of the foundation rising part, and between the lower gravel bag and the upper gravel bag,
The base isolation structure of a building according to claim 2 or 3. In order to restrain a plurality of the lower gravel bags, further comprising a restraining bag that accommodates the plurality of lower gravel bags,
The base isolation structure for buildings according to claim 4. A heat input port that is provided through the top and bottom pressure platen portions so as to store heat in the upper gravel bag by guiding the air heated by solar heat downward from above the basic pressure platen portion,
A heat output port for supplying air warmed by the heat stored in the upper gravel bag to the upper chamber, and provided in the basic pressure-resistant panel portion so as to penetrate the upper and lower sides away from the heat input port; Prepared,
The base isolation structure for a building according to claim 4 or 5. The upper gravel bag is breathable,
Further comprising a ventilation guide sheet comprising a lower sheet portion in contact with the lower surface of the upper gravel bag and a side sheet portion extending upward from the edge of the lower sheet portion,
Between the ventilation guide sheet and the basic pressure-resistant portion, a ventilation passage serving as a passage of air passing from the heat input port to the heat output port through the upper gravel bag was formed.
The base isolation structure for a building according to claim 6. In order to transmit the heat stored in the upper gravel bag to the room through the basic pressure-resistant panel part, an indoor floor was laid directly on the basic pressure-resistant panel part.
The base isolation structure for a building according to claim 6 or 7.

Images