JP4967105B2 - Seismic isolation method for buildings - Google Patents

Description

  The invention of the present application relates to a building, and particularly to a seismic isolation technique in a building.

Japan is a country with many earthquakes. Against the backdrop of lessons learned from the Great Hanshin Earthquake and other major earthquakes, development of building technologies that take earthquake countermeasures into account, such as seismic isolation technology, is underway. In addition, due to a series of earthquake-proof camouflage problems, interest in the structural parts of buildings has become very high.
Among these, as for the geological division structure of a building, for example, as disclosed in JP-A-9-275160, an artificial ground material made of foamed resin (foamed polystyrene) is laid, and a concrete material is provided thereon. The structure has been devised.
It can be said that such a geotechnical part structure embeds lightened artificial ground material, thereby reducing the load of the entire building on the ground below it. This is a technique for reducing ground contact pressure by replacing the ground (soil) directly under the building with a lightweight artificial ground material, thereby preventing subsidence such as uneven settlement. In this specification, the simple ground means not the artificial ground but the original ground of the site.
JP-A-9-275160

However, the foamed resin artificial ground material is drainable, and even when the underground water level rises, it does not have a structure in which water accumulates at that portion.
The invention of the present application is to solve the problem of obtaining a new seismic isolation effect by adopting a ground structure in which water continues to accumulate at a position directly below the foundation of the building.

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application reduces vibrations of a building when an earthquake occurs in a building including a base portion and a building portion constructed on the base portion. A seismic isolation method,
A waterproof layer is embedded in the ground immediately below the foundation, and the waterproof layer has a bottom portion and a side portion extending upward from the end of the bottom portion. It is a structure where water accumulates inside the side when rising, and a structure where water continues to accumulate inside the side even after the ground water level falls,
The water that continues to accumulate inside the side portion of the waterproof layer reduces the vibration of the building when an earthquake occurs.
In order to solve the above-mentioned problem, the invention according to claim 2 is characterized in that, in the configuration of claim 1, a phase difference is caused in the vibration of the earthquake due to the water continuously accumulated inside the side portion of the waterproof layer. It has a configuration for reducing vibration.
In order to solve the above-mentioned problem, the invention according to claim 3 is configured such that, in the configuration of claim 1 or 2, the center of gravity of the entire building is lowered by the water continuously accumulated inside the side portion of the waterproof layer. Have.
In order to solve the above-mentioned problem, the invention according to claim 4 is the structure according to any one of claims 1 to 3, wherein the ground is stored when an earthquake occurs due to water continuously accumulated inside the side portion of the waterproof layer. It has the structure of inhibiting the resonance between the building and the building.
In order to solve the above-mentioned problem, the invention according to claim 5 is the structure according to any one of claims 1 to 4, wherein a number of resin blocks that are lighter than ground soil are arranged below the foundation. A resin block layer that has been replaced by ground is provided, and the waterproof layer is provided below the resin block layer, and each resin block has a water-permeable opening. Have.

  As described below, according to the invention of each claim of the present application, the water that continues to accumulate at a position immediately below the foundation of the building reduces vibration during an earthquake and uses the accumulated water during drought. You can also have a two-bird effect with one stone.

Next, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described.
FIG. 1 is a schematic front view of a building of a reference example. The building shown in FIG. 1 is composed of an artificial ground 1 provided below the ground surface and a building part 2 constructed on the artificial ground 1. And the artificial ground 1 is provided with the resin block layer 3 provided so that the area | region of the predetermined depth below the ground surface may be occupied. A reference layer 4 is provided on the resin block layer 3, and the building part 2 is constructed on the reference layer 4. The artificial ground 1 occupies a region almost immediately below the building part 2. That is, the horizontal area occupied by the building part 2 and the horizontal area occupied by the artificial ground 1 are substantially the same.

A major feature of this building is that the resin block layer 3 is formed by arranging a large number of resin blocks 5 made of resin (excluding foamed resin), so that water can enter inside through the openings. is there.
FIG. 2 is a schematic view of the resin block 5 constituting the resin block layer 3 shown in FIG. 1, wherein (1) is a schematic plan view and (2) is a schematic front view. The resin block 5 includes a base portion 51 that is in a horizontal posture and leg portions 52 that are formed to extend vertically from the base portion 51. The base portion 51 has a square plate shape as a whole. A large number of openings 50 are formed in the base portion 51 for weight reduction and water flow.

A total of four leg portions 52 are provided at each corner position of the square base portion 51. The position of the leg 52 is a position slightly inside from the edge of the corner. Each leg part 52 is located on a diagonal line, and all the distances from the center of the base part 51 are the same.
Each leg 52 is a substantially prismatic part as a whole. However, the inside of each leg part 52 is hollow for weight reduction. Each leg portion 52 has the largest cross-sectional area at the portion connected to the base portion 51, and gradually becomes a smaller cross-sectional area as the distance from the base portion 51 increases. That is, it has a trapezoidal shape when viewed from the front.
The height of each leg 52 is the same. On the upper end surface of each leg 52, a fitting projection 53 (hereinafter referred to as a fitting projection) 53 is formed. The fitting protrusion 53 is a part for combination with another resin block 5 positioned on the upper side.

As shown in FIG. 2A, two fitting protrusions 53 are formed on the upper end surface of each leg portion 52. As shown in FIG. 2A, each fitting protrusion 53 is provided on a diagonal line in the direction from obliquely upper left to obliquely lower right in the substantially square upper end surface shape of each leg portion 52.
A fitting hole (hereinafter referred to as a fitting hole) 54 is formed on the upper end surface of each leg portion 52. The fitting hole 54 is a hole into which the fitting protrusion 53 is fitted. Two fitting holes 54 are also provided on each upper end surface. The fitting hole 54 is provided on a diagonal line in a direction from diagonally upper right to diagonally lower left when viewed in a plan view. In other words, each fitting hole 54 is arranged symmetrically with each fitting protrusion 53 on the upper end surface of each leg portion 52.

Since such resin blocks 5 are assumed to be carried and arranged by a person, the resin blocks 5 are of a size that can be carried by a person. For example, the base 51 has a side of about 500 to 600 mm, and the leg 52 has a length of about 200 to 500 mm.
As will be described later, the resin block 5 is used for ground replacement as a lightweight artificial ground material, and is made as light as possible within a range in which necessary strength is ensured. The resin block 5 is also lightweight in the sense that it can be carried by a person. Specifically, each resin block 5 has a weight of about 6 kg to 8 kg.

  Such a resin block 5 is entirely made of polypropylene and is manufactured by injection molding. As such a resin block 5, since the thing for civil engineering, such as road construction, is marketed as a can block (brand name) from Hayashi Bussan (Hitachi City, Ibaraki Prefecture), you may apply this. As a material of the resin block 5, a resin block 5 made of polyethylene, polyolefin, ABS resin or the like may be used in addition to polypropylene.

Next, the point which assembles the resin block 5 mentioned above and makes it the resin block layer 3 is demonstrated. As shown in FIG. 1, the resin blocks 5 are laid side by side in the horizontal direction and the vertical direction without any gaps. At this time, in the vertical direction, assembly is performed by fitting each fitting projection 53 into each fitting hole 54.
That is, as shown in FIG. 1, the lower resin block 5 is arranged with the legs 52 facing upward. Then, another resin block 5 is disposed thereon with the leg portion 52 facing downward. At this time, the legs 52 are brought into contact with each other so that the fitting protrusions 53 are fitted into the fitting holes 54.
In addition, another resin block 5 with the leg portion 52 facing upward is stacked on the resin block 5 arranged with the leg portion 52 facing downward. At this time, the resin block 5 is provided on the base portion 51. A protrusion (hereinafter referred to as a base protrusion) 55 prevents horizontal displacement.

As shown in FIG. 2A, four base protrusions 55 are provided, and are provided at intervals of 45 degrees concentrically with the center of the base portion 51. The base portion 51 is provided with a hole (hereinafter referred to as a base hole) 56 into which the counterpart base protrusion 55 is fitted. As shown in FIG. 2A, four base holes 56 are also provided on the circumference concentric with the base portion 51 at intervals of 45 degrees. The positional relationship between the base protrusion 55 and the base hole 56 is shifted so as to be exactly the same position when the base portion 51 is turned over.
Accordingly, when the two resin blocks 5 are overlapped with the base portions 51 being in contact with each other, one base projection 55 is fitted into the other base hole. For this reason, the horizontal position shift is prevented.

As for the assembly of the resin block 5, the horizontal resin block 5 is also connected. This point will be described with reference to FIG. FIG. 3 is a view showing a horizontal connecting structure of the resin block 5 shown in FIG. 2, wherein (1) is a schematic plan view and (2) is a schematic front sectional view.
A connector 6 is used to connect the resin blocks 5 in the horizontal direction. As shown in FIG. 3B, the connector 6 has a shape including a plate portion 61 and an insertion protrusion 62 provided so as to protrude from the plate portion 61 at a right angle. The plate part 61 is substantially rectangular, and the insertion protrusions 62 are provided on both upper and lower surfaces. Further, four insertion protrusions 62 are provided on both the upper and lower surfaces, and are provided on the respective diagonals of the plate portion 61 at positions equidistant from the center.

On the other hand, as shown in FIG. 2 (1), insertion holes 57 are formed at each corner of the resin block 5. The insertion hole 57 has a shape and size suitable for the shape and size of the cross section of the insertion protrusion 62.
When the resin blocks 5 are connected in the horizontal direction, as shown in FIG. 3A, the resin blocks 5 are packed and arranged so that the corners are adjacent to each other. And each corner | angular part is connected with the connector 6. FIG. That is, the insertion protrusion 62 is inserted into each insertion hole 57 of the four adjacent resin blocks 5.
As shown in FIG. 3B, the insertion protrusion 62 protruding upward is used for connecting the resin blocks 5 arranged on the upper side. By arranging the resin blocks 5 so that the insertion protrusions 62 are inserted into the insertion holes 57, the resin blocks 5 in the horizontal direction are connected.

The resin block layer 3 formed by assembling such a resin block 5 has a sufficient strength as a component of the artificial ground 1 of the building despite being lightweight. As an example, in the case of the resin block 5 having a configuration as shown in FIG. 2, for example, in the case of the resin block 5 shown in FIG. 2, one resin block 5 can withstand a load of 0.53 t to 3.2 t. Such resin blocks 5 are overlapped with the leg portions 52 so that they can withstand loads up to 16 t / m ² .

Such a resin block layer 3 is applied to a recess formed by digging a ground surface of a site where a building is built to a predetermined depth. Moreover, the assembled resin block layer 3 is covered with a water-permeable sheet on the left and right side surfaces and the bottom surface, and is covered with a waterproof sheet.
As shown in FIG. 1, a retaining wall layer 7 is provided around the resin block layer 3. The retaining wall layer 7 is formed by stacking a large number of perforated foam resin blocks (perforated foam resin blocks) 71.

FIG. 4 is a schematic perspective view of the perforated foamed resin block 71. As shown in FIG. 4, the perforated foamed resin block 71 has a rectangular parallelepiped shape as a whole. And the elongate groove | channel 72 which intersects at right angle is formed in the upper surface and the lower surface. A through hole 73 that penetrates the perforated foamed resin block 71 in the thickness direction is formed. The through holes 73 are provided at a plurality of locations including the intersections of the grooves 72.
A reference layer 4 is provided on the resin block layer 3. The reference layer 4 is for obtaining a horizontal plane that serves as a reference when the building part 2 is constructed. The reference layer 4 includes a cover layer 41 covering the resin block layer 3 and a discarded concrete layer 42 provided on the cover layer 41.

The cover layer 41 is formed by spreading a foamed resin plate 43. The foamed resin plate 43 is a square having a size of about 1820 mm × 910 mm, and the thickness may be about 30 to 50 mm. The foamed resin plate 43 here does not need to be perforated.
The discarded concrete layer 42 is solid. The thickness of the discarded concrete layer 42 may be about 50 mm to 100 mm. The upper surface of the reference layer 4 (here, the upper surface of the discarded concrete layer 42) is constructed to be a horizontal flat surface.
Although it is possible to construct the concrete layer 42 directly without the cover layer 41, it is difficult to construct the concrete concrete as it is because the resin block 5 has many openings. In some cases, a waterproof sheet is used in place of the foamed resin plate 43, and the upper surface of the resin block layer 3 is covered with the waterproof sheet and then a discarded concrete layer is provided.

Such a reference layer 4 also constitutes the artificial ground 1. That is, the artificial ground 1 is mainly composed of the resin block layer 3 and the reference layer 4.
A base portion 21 is provided on the reference layer 4, and the building portion 2 is constructed thereon. The foundation part 21 is a foundation made of concrete containing reinforcing bars. The foundation part 21 may be a solid foundation or a cloth foundation (independent foundation).

Next, the action of the artificial ground 1 and the digging depth of the site for forming the artificial ground 1 will be described.
FIG. 5 is a diagram showing the action of the artificial ground 1 in the building of the reference example and the digging depth of the site for forming the artificial ground 1.
As shown in FIG. 5 (1), in the site where the building was built, the entire load (hereinafter referred to as total load) W including the building part and the foundation part is applied to the ground. Gravity (pressure) per unit area applied to the ground by the total load W is called ground pressure. The ground pressure (indicated by P in FIG. 5) is a pressure at the lowermost surface of the building because it is a force that the entire building presses against the ground.

When the total load W is applied to the ground, the ground itself receives the building with a force according to the gravity balance, and if the ground pressure P does not exceed a certain limit, a subsidence accident such as non-uniform subsidence does not occur. The pressure at which the ground receives the building is called natural ground strength (hereinafter simply referred to as ground strength) and is represented by qa. The ground strength qa varies depending on the type of ground, and is weaker in soft ground containing more water. In addition, there are long-term proof strength and short-term proof strength (power that can withstand a rapid vibration in a short period due to an earthquake, etc.), but the following explanation assumes long-term proof strength.
For example, when building a wooden house up to about three stories, the earth strength qa is required to be about 30 to 50 kN / m ² . However, it becomes less than 30 kN / m ² in soft ground. The earth bearing strength qa is required to have a ground pressure greater than P. If P> qa, a settlement accident may occur.

As shown in FIG. 5 (1), it is assumed that there is a building with a total load W, and the ground pressure is P. At this time, an area of the ground (underground) from the ground surface in an amount corresponding to the weight of W is defined as S. At the lowermost surface of this region S, the contact pressure is generated by the load of 2W, but at the same depth level in the surrounding ground, the contact pressures P ′ and P ″ due to the load of W are generated. This is a state where the ground strength qa is receiving.
Here, as shown in FIG. 5 (2), the ground below the building is dug down to create a space (concave portion) corresponding to the area S. It is assumed that a support structure (that is, artificial ground) in which the load can be regarded as substantially zero is constructed in this space. If it carries out like this, since the load of the artificial ground is zero, the ground pressure in the bottom face of the recessed part formed by digging down remains the ground pressure P by the load W of the building. For this reason, it becomes substantially equal to the ground contact pressure P ′, P ″ in the surrounding ground at that depth, so that no subsidence accident due to the total load W of the building occurs.
This is a technology that prevents the subsidence by making the ground pressure equal to the ground pressure in the surrounding ground by creating a zero-load space by removing the ground under the building by the load of the building. I can say that. In other words, it can be said to be a technology that floats buildings like ships.

However, in practice, it is not necessary to remove the load of the building, and it is only necessary to remove the amount corresponding to the ground pressure P due to the building exceeding the ground strength qa. Therefore, when the ground replacement by such a lightweight artificial ground material is expressed by a general formula, it is as follows.
d = (P−qa) / γ
In this equation, d is the depth of digging the ground (m), P is the contact pressure (kN / m ² ) due to the total load (including the artificial ground) W, qa is the ground strength (kN / m ² ) of the ground, γ is gravity (kN / m ³ ) per unit volume of the soil of the ground. In other words, it is only necessary to dig up the portion of the contact pressure exceeding the earth bearing strength divided by the gravity per unit volume of soil and replace it with lightweight artificial ground material.
In the above formula, d is a minimum value, and if it is dug deeper (d is increased), the effect of preventing settlement is further increased. In other words, the above formula is
d ≧ (P−qa) / γ
Is correct.

  In each of the above formulas, dγ is obtained by multiplying the weight per unit volume of the soil of the ground by the digging depth. This is the gravitational force (pressure) per unit area that the entire amount of soil that has been dug and taken out in the recessed space that has been dug down was originally acting in that space. Such gravity is called pre-loading pressure. The ground replacement by the lightweight artificial ground material as described above is nothing but a method for removing the preceding top-loading pressure by the amount that the ground pressure exceeds the ground strength, thereby preventing the settlement.

  In the actual foundation design, the ground strength of the ground of the construction site and the weight per unit volume of the soil are examined in advance. Then, the total weight W is obtained by adding the total weight of the building portion 2 and the total weight of the artificial ground 1 including the resin block layer 3, and the contact pressure P is calculated. The contact pressure P is a value obtained by dividing the total weight W by the area where the total load W is applied to the ground (in this example, the area at the bottom of the artificial ground 1). Each value obtained in this way is substituted into the above formula to obtain the minimum value of d, and a certain amount of value is adopted as the actual d with a margin from that value.

Next, the foundation construction method having the above structure will be described with reference to FIG. FIG. 6 is a schematic view showing a construction method of the artificial ground 1 of the building shown in FIG. From the following description, a more specific structure of the artificial ground 1 will be clarified.
First, the site where the building is built is dug down to form the recess 8 (FIG. 6 (1)). The horizontal area to be dug is the same as or slightly wider than the construction area of the building 2. The depth to dig is appropriately determined according to the above formula.

Next, the bottom surface and side surfaces of the concave portion 8 formed by digging down are leveled, and ground with crushed stone or the like. The bottom and side surfaces of the recess 8 are covered with the water permeable sheet 81. Next, crushed stone 82 is spread on the bottom surface 8, and crushed stone 82 is spread on the side surface.
Next, the retaining wall layer 7 is constructed inside the crushed stone 82. As described above, the perforated foamed resin block 71 having water passage grooves and holes is stacked to form the retaining wall layer 7. After the retaining wall layer 7 is formed in a circumferential shape along the side surface, the resin block layer 3 is applied to the inside thereof. In advance, a water-permeable sheet is laid on the bottom surface and side surfaces, and the resin blocks 5 are arranged on the inside. That is, as described above, after the resin blocks 5 are arranged horizontally and connected to each other, the resin blocks 5 are further stacked and assembled to form the resin block layer 3 (FIG. 6 (3)). And the upper surface of the resin block layer 3 is covered with the waterproof sheet 30.

Thereafter, a foamed resin plate 43 is laid on the resin block layer 3 to form a cover layer 41, and a discarded concrete layer 42 is applied thereon. Then, when filling back with crushed stone or soil to fill the gap remaining in the crushed stone 82 or the like, the artificial ground 1 is finally completed (FIG. 6 (4)). The discarded concrete layer 42 is positioned lower than the ground surface, but the upper surface of the discarded concrete 42 may be the same height as the ground surface or may be positioned higher than the ground surface. In some cases, the concrete layer 42 is disposed from the ground surface to a predetermined height.
In addition, about the building part 2, it is not specifically limited, It can design and construct freely like a conventional thing.

As described above, the building of the reference example is provided with the resin block layer 3 in which the lightweight resin blocks 5 are arranged and assembled in the portion from which the pre-loading pressure is removed, so that the ground is replaced. Accidents are suppressed.
Further, the retaining wall layer 7 prevents the side surface of the recess from collapsing, and prevents earth and sand from entering the resin block layer 3. As described above, the side surfaces of the resin blocks 5 stacked one above the other are openings, and the action to protect the side surfaces of the recesses is weak as it is. Therefore, the retaining wall layer 7 is provided to protect the side surface. Also in this case, the perforated foamed resin block 71 is used so that water permeability is not hindered.

  Moreover, since the perforated foamed resin block 71 is lightweight, it can also be used as a part of a lightweight artificial ground. That is, in the structure shown in FIG. 1, the load of the building part 2 is not directly applied to the retaining wall layer 7, but the retaining wall layer 7 is positioned immediately below the building part 2 so that the A load may be applied. In this case, the retaining wall layer 7 made of the perforated foamed resin block 71 is a part of the lightweight artificial ground and contributes to the ground replacement as described above.

Further, the point that water can freely enter the resin block layer 3 has a particularly advantageous structure in terms of construction on soft ground. This point will be described with reference to FIG. FIG. 7 is a schematic view showing the effect of the artificial ground 1 shown in FIG. In FIG. 7, (1) shows the artificial ground 1 formed by laying and stacking many foamed resin blocks 9 as in the prior art, and (2) shows the artificial ground 1 of the reference example.
As shown in FIG. 7 (1), in the artificial ground 1 formed by laying and stacking a large number of foamed resin blocks 9, water can slightly enter the gap between the foamed resin blocks 9, but the foamed resin block 9 itself passes through. There is no water, and the artificial ground 1 as a whole is drainable (meaning that it does not allow water to enter the interior). For this reason, when a large amount of water 100 invades into the ground due to heavy rain and the ground water level rises, the water 100 tends to reach the ground surface (submerge).

  On the other hand, as shown in FIG. 7 (2), according to the artificial ground 1 formed by the resin block layer 3, since water freely enters the resin block layer 3, the rise in the water level in the ground is alleviated, and the flooded water The possibility of reaching up to is reduced. In other words, the resin block layer 3 is used as a water storage layer (pool) at the time of water increase together with ground replacement by a lightweight artificial ground material. For this reason, it becomes a very preferable thing as what is constructed to a soft ground. For example, a place that was previously a rice field or swamp often has a high underground water level and is likely to be flooded due to heavy rain, but even in such a place, the artificial ground 1 should be constructed. In case of heavy rain, you can prevent flooding.

Moreover, in the artificial ground 1 which consists of the conventional foamed resin block 5, since the foamed resin block 9 does not have water permeability, if heavy rain falls during construction, it will be easy to raise | lift an accident. That is, in the stage before building the building part 2 after the foamed resin blocks 9 are laid side by side, if heavy rain falls and water accumulates in the recesses formed by digging, the foamed resin block 9 will rise. Will occur. In order to prevent this, during the construction of the foamed resin block 9 or at the stage before the construction of the building 2 is started after completion of construction, it is necessary to pump out water by a pump when heavy rain falls.
On the other hand, in the structure of the reference example, each resin block 5 itself has an opening and is rich in water permeability. Therefore, even if there is heavy rain during construction or after construction has been completed, the resin block 5 Accidents where the block 5 is lifted can be prevented. Therefore, there is no need for the trouble of pumping out water with a pump.

Next, the building where the seismic isolation method of the embodiment of the present invention is implemented will be described.
FIG. 8 is a schematic front view of a building in which the seismic isolation method according to the embodiment of the present invention is implemented. In the building shown in FIG. 8, the artificial ground 1 is used as a water reservoir so that it can be used during drought.
That is, in the building shown in FIG. 8, the waterproof layer 10 is provided on the bottom surface and the side surface of the recess formed by digging down. The waterproof layer 10 can be formed, for example, by laying a waterproof sheet or arranging a large number of waterproof plates and bonding them with a waterproof adhesive. As shown in FIG. 8, the waterproof layer 10 has a bottom portion and side portions extending upward from the end portion of the bottom portion.
In addition, the height of the side part of the waterproof layer 10 is in the middle of the depth of a recessed part as needed, and has not reached the ground surface. In this embodiment, it is about 1/3 of the height of the resin block layer 3. Moreover, the intake pipe 11 is provided so that the inner side of the side part of the waterproof layer 10 and the ground surface may be connected, and the unillustrated pump is provided in the intake pipe 11.

In this building, when heavy rain falls and the underground water level rises, water enters the inside of the side portion of the waterproof layer 10. The infiltrated water continues to accumulate inside the side portion of the waterproof layer 10 even after the water is pulled and the ground water level is lowered. The accumulated water can be pumped through the water intake pipe 11 during drought and used for watering the garden. In addition, the effect of ground replacement by a lightweight artificial ground material is the same as that of the reference example mentioned above.
According to this building, a subsidence accident can be prevented by the artificial ground 1 replaced with the ground, and the artificial ground 1 can be used as a water reservoir at the time of water increase, and the water in the waterproof layer 10 can be used at the time of drought, Has the effect of three birds with one stone.

Next, the building which concerns on another structure is demonstrated.
FIG. 9 is a schematic front view of a building according to another configuration. In the artificial ground 1 of this building, the concave portion has a deep shape immediately below the central portion in the horizontal direction of the building portion 2 and a shallow shape immediately below the peripheral portion in the horizontal direction, and the resin block layer 3 is also horizontally aligned with the horizontal portion of the building portion 2. The shape is thick just below the center in the direction and thin just below the periphery in the horizontal direction.
Although details of the resin block layer 3 are omitted in FIG. 9, as can be understood from the above description, the resin block layer 3 having such a shape can be obtained by appropriately changing the arrangement of the resin blocks 5. it can.

The technical significance of the artificial ground 1 will be described with reference to FIG. FIG. 10 is a schematic front view showing the technical significance of the artificial ground 1 of the building shown in FIG. As described above, the ground pressure is applied to the ground according to the total weight of the building, and the ground strength acts against this. At this time, stress (ground stress) corresponding to the total weight of the building is generated in the ground.
Since the underground stress is generated by the ground pressure, as shown in FIG. 10, the underground stresses S1 to S4 are distributed so as to spread from the lowest points of the building. In the ground, the distribution of the stress S seen in a plane parallel to the ground surface is a combination of the stresses S1 to S4 from the lowermost points of the building. Therefore, as shown in FIG. 10, the composite stress S has a large distribution in the portion immediately below the central portion of the building and a small distribution in the peripheral portion.

  When the stress of such distribution occurs as a whole, as shown in FIG. 1, it is sufficient as described above even if the concave portion having a uniform depth is formed and the thickness of the resin block layer 3 is uniform. In this way, the effect of preventing a sinking accident can be obtained. However, if the thickness distribution of the resin block layer 3 is made to correspond to the stress distribution, it is possible to obtain the effect of preventing a settlement accident while efficiently using a limited amount of the resin block 5. The building of this reference example has technical significance in this respect.

That is, as shown in FIG. 9, the ground is deeply dug directly under the central portion in the horizontal direction of the building 2 to largely remove the preceding upper loading pressure, and shallowly dug just under the horizontal peripheral portion to remove the preceding upper loading pressure less. Then, the resin block layer 3 is thickened immediately below the central portion in the horizontal direction of the building part 2 (the number of stacked stages of the resin blocks 5 is increased), and the resin block layer 3 is thinned immediately below the peripheral part in the horizontal direction (of the resin block 5 Reduce the number of stacks). This is the result of adapting the distribution of ground replacement by the lightweight artificial ground material (distribution of ground pressure relaxation) to the stress distribution. That is, as shown in FIG. 10, the ground replacement is performed with the distribution R that protrudes downward in accordance with the distribution of the stress S that protrudes upward. In this way, the contact pressure is efficiently relieved in the central portion where the stress is large, and a more uniform underground stress distribution S ′ is obtained.
If it does in this way, since the use efficiency of the resin block 5 improves, the usage-amount of the whole resin block 5 can be reduced while preventing a settlement accident effectively, and construction cost can be held down cheaply.

Next, a building having another configuration will be described with reference to FIG. FIG. 11 is a schematic front view showing the configuration of the resin block layer 3 in yet another building.
First, when the resin block 5 shown in FIG. 2 is used, the leg portions 52 may not be abutted and stacked as described above, but may be sequentially stacked with the leg portions 52 facing upward. In this case, a cover resin block provided to cover the top resin block 5 is prepared separately. The resin block for a cover is a shape without the leg part 52 of the resin block 5 shown in FIG.
Further, the shape of the resin block 5 may be as shown in FIG. FIG. 11 (2) is a schematic front sectional view, but the one shown here is a rectangular parallelepiped box shape having an opening at the top, and a shape in which a reinforcing leg 52 is formed at the center. Is. Similarly, a large number of openings 50 are provided on the side and bottom surfaces of the box to ensure water flow and light weight.

Next, the relationship between the area occupied by the artificial ground 1 and the area occupied by the building part 2 in the horizontal direction will be described with reference to FIG. FIG. 12 is a diagram showing the relationship between the area occupied by the artificial ground 1 and the area occupied by the building part 2 in the horizontal direction.
In the said building, the area | region which the artificial ground 1 occupies in the horizontal direction and the area | region which the lowest part of the building part 2 occupy were the same. That is, for example, when the lowermost part of the building part 2 is a rectangle, the artificial ground 1 is also a rectangle of the same size and occupies a region immediately below the building part 2. However, when implementing the present invention, the two regions do not have to be the same. That is, the area of the artificial ground 1 may be narrower than the building part 2 as shown in FIG. 12 (1), and the area of the artificial ground 1 may be larger than the building part 2 as shown in FIG. 12 (2). .

However, in the case shown in FIG. 12 (1), the preceding top loading pressure is not removed in the portion directly under the building part 2 not occupied by the artificial ground 1. The gravity of the soil in this part must also be included in the total load in the calculation. Therefore, when the load on the building is large or the earth bearing strength is low, the effect of preventing settlement accidents cannot be obtained sufficiently. There may be cases.
In the case of FIG. 12 (2), the resin block layer 3 at the protruding portion is not greatly involved in the reduction of the ground pressure. When the horizontal resin block 5 is sufficiently connected, there is an effect of dispersing the ground pressure acting at a position immediately below the horizontal peripheral part of the building part 2, but the peripheral part is grounded as described above. Since the medium stress is small, the distribution of ground pressure is not so necessary. Therefore, it can be said that the resin block 5 is used after being dug more than necessary.
Compared to these cases, the above-mentioned building uses a necessary and sufficient amount of resin blocks 5 by digging up a necessary and sufficient area, and can be said to be optimal in terms of effect and cost.

  In the building of each structure described above, the structure in which water enters and accumulates in the resin block layer 3 when the underground water level rises during rainfall is also good in terms of earthquake resistance. One of the mechanisms by which the seismic resistance is improved when water enters and accumulates in the resin block layer 3 corresponds to an action called dynamic interaction. The dynamic interaction is an action in which a soft ground exists on a highly rigid ground, and when vibration (earthquake) is transmitted there, a phase difference is generated in the vibration and the vibration is reduced. There is a similar effect in the building of each structure, and when water accumulates in the resin block layer 3, the way of vibration transmission is slowed down there, resulting in a seismic isolation effect.

  Another mechanism for improving earthquake resistance is the ballast effect caused by water accumulation. When a liquefaction phenomenon occurs due to an earthquake, water (excess pore water due to the earthquake) enters the resin block layer 3 and has an effect of lowering the center of gravity of the entire building. As a result, the building is stabilized and vibration is reduced. This effect is similar to that of large ship ballast tanks and anti-rolling tanks.

Yet another mechanism for improving earthquake resistance is the effect of inhibiting the resonance between the site ground and the building. As is well known, when an earthquake occurs, the site ground shakes predominately with a period specific to the site, and this period is called the predominate period. And the building itself sways with its own period. When the prevailing cycle of the site ground and the natural cycle of the building become closer, the building will sway in resonance with the shaking of the site ground, causing significant damage to the building.
Here, as is well known, the P wave (pitch) is transmitted in water and air, but the S wave (roll) is not transmitted in water and air. Therefore, when the artificial ground 1 having many cavities is provided under the building portion 2 as in the building of each configuration, or when the water is accumulated in the artificial ground 1, the S wave is not transmitted there. As a result, assuming that the prevailing period of the site ground and the natural period of the building are close to each other, the artificial ground 1 acts so as to inhibit (invert) resonance, and the shaking of the building part 2 is reduced.

In each of the above effects, the seismic isolation action of water is obtained particularly when the underground water level rises and water enters the resin block layer 3 during precipitation or when a liquefaction phenomenon occurs. Of course, it is also obtained in the building shown in FIG. In the case of the building shown in FIG. 8, even if the underground water level drops below the lowest part of the artificial ground 1, water is accumulated, so that even if an earthquake occurs in this state, the seismic isolation effect can be obtained. .
The above-mentioned seismic isolation effect is basically the same not only for vibration caused by earthquakes but also for vibrations caused by traffic or construction of trucks or trains.

The basic structure of each building is a structure in which a resin block layer 3 is formed by arranging resin blocks 5 in a recess formed by digging, and includes a reference layer 4 and a retaining wall layer 7 as shown in FIG. That is not a requirement.
If the uppermost surface of the resin block layer 3 is a horizontal flat surface, the reference layer 4 is unnecessary. Moreover, if the resin block 5 which has a side part as shown in FIG.11 (2) is used, a retaining wall may be made in the side part, and a retaining wall block becomes unnecessary. However, in this case as well, a fine water-permeable sheet or the like may be interposed so that earth and sand do not enter from the opening.
Moreover, the resin block 5 may be implemented even if it is arranged in the horizontal direction only (one-stage resin block 5). Moreover, when the horizontal region of the building part 2 is small, there is no need to arrange the resin blocks 5 in the horizontal direction (only one resin block 5 in the horizontal direction), and the resin block layer 3 is simply arranged in the vertical direction. In some cases, it can be formed.

It is the front schematic of the building of a reference example. It is the schematic of the resin block 5 which comprises the resin block layer 3 shown in FIG. 1, (1) is a plane schematic diagram, (2) is a front schematic diagram. It is the figure shown about the connection structure of the horizontal direction of the resin block 5 shown in FIG. 2, (1) is a plane schematic diagram, (2) is a front cross-sectional schematic diagram. 3 is a schematic perspective view of a perforated foamed resin block 71. FIG. It is the figure shown about the operation of the artificial ground 1 in the building of a reference example, and the digging depth of the site | site for forming the artificial ground 1. FIG. It is the schematic shown about the construction method of the artificial ground 1 of the building shown in FIG. It is the schematic shown about the effect of the artificial ground 1 shown in FIG. 1, (1) shows the artificial ground 1 formed by laying and stacking many foamed resin blocks 9 like the past, (2) is a reference example The artificial ground 1 is shown. It is a front schematic diagram of the building where the seismic isolation method of the embodiment of the present invention is implemented. It is a front schematic diagram of the building concerning another composition. It is the front schematic which showed about the technical significance of the artificial ground 1 of the building shown in FIG. It is the front schematic shown about the composition of resin block layer 3 in still another building. It is the figure shown about the relationship between the area | region which the artificial ground 1 occupies in the horizontal direction, and the area | region which the building part 2 occupies.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Artificial ground 2 Building part 21 Base part 3 Resin block layer 4 Reference layer 41 Cover layer 42 Discarded concrete layer 5 Resin block 6 Connector 7 Retaining wall layer 71 Perforated foamed resin block 81 Permeable sheet 82 Crushed stone 10 Waterproof layer 11 Intake pipe

Claims (5)

In a building composed of a foundation part and a building part built on the foundation part, it is a seismic isolation method that reduces the vibration of the building when an earthquake occurs,
A waterproof layer is embedded in the ground immediately below the foundation, and the waterproof layer has a bottom portion and a side portion extending upward from the end of the bottom portion. It is a structure where water accumulates inside the side when rising, and a structure where water continues to accumulate inside the side even after the ground water level falls,
A method of seismic isolation in a building, characterized by reducing the vibration of the building when an earthquake occurs with water that continues to accumulate inside the side of the waterproof layer. The seismic isolation method for buildings according to claim 1, wherein a phase difference is caused in the vibration of the earthquake by the water continuously accumulated inside the side portion of the waterproof layer, thereby reducing the vibration. The seismic isolation method for a building according to claim 1 or 2, wherein the center of gravity of the entire building is lowered by water that continues to accumulate inside the side portion of the waterproof layer. 4. The seismic isolation method for a building according to claim 1, 2 or 3, wherein the water that continues to accumulate inside the side portion of the waterproof layer inhibits resonance between the ground and the building when an earthquake occurs. . Under the base portion, a resin block layer that has been subjected to ground replacement by providing a number of resin blocks that are lighter than the ground soil is provided side by side, and the waterproof layer is disposed under the resin block layer. The seismic isolation method for buildings according to claim 1, wherein each resin block has a water-permeable opening.

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