JPH04185820A - Foundation structure of building - Google Patents

Abstract

PURPOSE:To construct housing even on soft ground at low cost by a method in which an aerated cement mortar layer whose unit volumetric weight is smaller than the soil of excavated pit is provided and a foundation is constructed on the aerated cement mortar layer. CONSTITUTION:The ground where strip footing 12 is to be constructed is excavated to form a pit P, and an aerated cement mortar slurry 10 is placed into the pit P. After the cement mortar slurry 10 is cured for some period of time and leveling concrete 18 is placed on the mortar 10 layer. A formwork for strip footing 12 is set on the concrete 18 and concrete is placed, or a precast strip concrete footing 12 formed in factory is installed. Afterwards, the pit P is embedded with soil 19. The foundation can thus be constructed even on soft ground at low cost without improving the ground.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a foundation structure for a building suitable for constructing a foundation for a house or the like on poor ground such as soft ground.

[Conventional technology]

Generally, when constructing the foundation for a building, a hole is formed by cutting the root, and after laying chestnut stone at the bottom of the hole, pouring concrete, and then forming a cloth foundation using concrete, for example. do. However, if the ground is soft, the foundation is formed after improving the ground as described below.

Foundation construction methods when constructing a house on soft ground include the prefabricated pile method, in which prefabricated piles such as steel pipe piles, PC-RC-PHC piles, and lightweight friction piles are driven, and the cast-in-place method, in which concrete is poured into the ground on site. There are pile methods and ground improvement methods that improve the ground by mixing and stirring soil improvement materials into the ground.

[Problem to be solved by the invention]

However, all of these methods require large construction machines, resulting in large costs and long construction periods.

This invention was made in view of the above-mentioned conventional problems, and an object thereof is to provide a foundation structure for a building that shortens the construction period and is inexpensive to construct.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a layer of cellular mortar having a lighter unit weight Wt than soil in an excavated hole, and provides a foundation on this layer of cellular mortar.

[Effect]

According to this invention, the present land 1 before excavation includes a soft ground layer in the lower part! In the ground where the subsidence of the ground has converged and is stable with respect to the amount of It, the excavated hole is provided with a layer of foam mortar whose unit weight W is lighter than the soil, so the excavated soil Since this will be replaced with light foam mortar, even if the weight of the foundation or building is added to the ground, the total weight added to the ground will not increase significantly. Therefore, even if the ground is soft, consolidation settlement will not progress, so there is no need to perform ground improvement.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the invention.

In FIG. 2, a building 17 such as a house has a cloth foundation 1
It is supported by 2. As shown in the plan view of FIG. 3, the cloth foundation 12 is formed along the 6P which is made of cloth.

In FIG. 1, a hole P is formed by cutting a root from a ground level L to a depth H, which is deeper than the conventional hole. In this hole P, 100 layers of cellular mortar are placed by pouring cellular mortar lO whose unit volume weight is lighter than soil.

Here, the cellular mortar 10 basically refers to cement,
It is made by solidifying a mixture of water, a foaming agent, and an admixture.The solidified cement contains air bubbles, and may contain aggregates and other substances. This foam mortar 10 has a density of 0.3 g/Ci to 1.2 g/cm
Unit body 1 has a weight of degree, therefore, unit body! It is lighter than soil whose lI weight is about 1.4 g/Ci to 2.0 g/CM. The compressive strength of the foam mortar 10 is 5Kg/a! It can be set to any value above and is sometimes called aerated concrete, air milk, salt mortar, etc.

The foamed mortar 10 includes one made from foamed cement milk and one made from foamed mortar.

The former foam mortar 10 is obtained by foaming cement milk on-site, so it can be produced continuously. The latter, foamed mortar 1G, is made by adding a foaming agent to mortar mixed during transportation in a ready-mixed concrete truck and foaming it on site. The slurry-like foam mortar IO is poured after cement milk or mortar and foam are uniformly mixed with a blender at the site.

A sacrificial concrete 18 is placed on the layer of the cellular mortar IO, and the cloth curtain W112 is further formed thereon. A layer of backfilling soil 19 is provided in the upper part of the hole P, and the footing 20 of the cloth foundation 12 is buried therein.

Next, a method of constructing the above structure will be explained.

First, a portion where the cloth foundation 12 is to be installed is excavated to form a six piece. Next, the foamed mortar 10 in the form of a slurry is forced into the hole P using a pump or the like and placed. After this pouring, there is a slight curing period, and then sacrificial concrete 18 is poured. After this pouring, the cloth foundation 12 is placed on top of the concrete 18,
In other words, it is installed above the 100 layers of cellular mortar by constructing a formwork and pouring concrete on site, or by bringing in and installing the Brecon cloth foundation 12 manufactured at a factory. After that, backfill soil 19 is backfilled.

In the above configuration, 100 layers of foam mortar, which has a lighter unit volume weight than soil, are provided on the six pieces of cloth excavated, so the cloth curtain a! Since the soil under 12 has been replaced with light foam mortar 10, the curtain 1112 and building 17
Even if the weight of (Fig. 2) is added, the total weight applied to the root cut bottom 13 is the fumaku i! There is no significant increase compared to before the formation of No. 12.

Therefore, even if the ground is bad, consolidation settlement will not progress, so there is no need to perform ground improvement unlike in the past.In other words, there is no need to take measures against soft ground below the root cutting bottom 13, resulting in lower costs. .

In addition, there is no need to drive ready-made piles below the cloth foundation 12, or to implement soft ground countermeasure methods such as piles driven in place or soil improvement methods, so the construction period is shortened accordingly.

Note that the smaller the unit volume weight of the cellular mortar 10, the lower its compressive strength, so choose one that has strength according to the conditions of use.

FIG. 4 shows a second embodiment.

In this figure, a layer of chestnut stone 14 is laid on the excavated 6P to improve penetration between the foamed mortar 10 and the ground, and the foamed mortar l is placed on top of this layer of chestnutstone 14.
A layer of O is provided. In this case, after digging the 6P, a chestnut stone 14 is laid and compacted, and then a foam mortar 10 is placed. The other configurations are the same as those in the first embodiment, and the same or equivalent parts are denoted by the same reference numerals.
The explanation and illustration thereof will be omitted.

FIG. 5 shows a third embodiment.

In this figure, a reinforcing cloth 16 is laid on the root cut bottom 13 and side surface 15 of the six P cut out.

This reinforcing cloth 16 is, for example, a nonwoven fabric made of water-permeable synthetic polymer fibers called geotextile.

In this case, after digging the 6P, a reinforcing cloth 16 is laid down, and then the foam mortar 10 is placed. The other configurations are the same as those in the first embodiment, and the same or corresponding parts are denoted by the same reference numerals, and detailed explanations and illustrations thereof will be omitted.

In this embodiment, reinforcing cloth I6 is laid on the root cut bottom 13,
By covering the soft root cut bottom 13, the footing of the worker becomes firm and work efficiency is improved. Moreover, since the reinforcing cloth I6 has a certain degree of tensile strength, it is possible to prevent uneven settlement.

Figure jlrB shows the fourth embodiment.

In this figure, a layer of cellular mortar 10 is provided in a hole P that has been dug, and a layer of backfilling soil 19A is provided between this layer of cellular mortar 10 and the sacrificial concrete 18. In this case, after digging hole P with cloth,
Place foam mortar lO, then backfill ±19A
and pour concrete 18. After that, the cloth foundation 12 is discarded and installed on the concrete 18.

The other configurations are the same as those in the first embodiment, and the same or corresponding parts are denoted by the same reference numerals, and detailed explanations and illustrations thereof will be omitted.

In this embodiment, since backfilling ±19A is inserted between the cloth foundation 12 and the layer of cellular mortar 10, it is possible to prevent the cellular mortar IO from buckling due to compression, and
Effective for pressing against lifting.

FIG. 7 shows five embodiments in tl.

Figure 2 of 1 Tomoe L・de! I can't cut it in size,
Two types of foam mortar 10. Two bubble mortar by IOA10. A layer of IOA is provided. Two types of foam mortar 10. The IOAs differ from each other in their compressive strength and unit volume weight, for example, the strength of the upper layer cellular mortar 10A and the unit body Iff! The amount is
It is set larger than that of the foam mortar lO in the lower layer.

In this case, after the hole P is dug, one of the cellular mortar 10 is placed, and then the other cellular mortar 10A is placed, and after this casting, the cellular foundation 12 is formed.

Two
Compression under the OA layer? Since the layer of cellular mortar 10 having a small jIL degree is provided, it is possible to prevent the cellular mortar 1o below from buckling under the load of the cloth foundation 12 or the like. Therefore, since the unit volume weight of the lower cellular mortar 10 can be reduced, the load applied to the ground can be reduced.
Because the compressive strength of the upper cellular mortar IOA is large, the name is omitted for the use of concrete. , 1 zo 1 is still foam mortar 10. IOA can easily change the quality for each layer. The other configurations are the same as those in the first embodiment, and the same or equivalent parts are given the same reference numerals, and their explanation and illustration will be omitted.

In addition, in each of the above examples, the foundation is Fumaku i! 12, but the foundation may be an independent foundation or a solid foundation other than the cloth foundation 12. It is also possible to omit the sacrificial concrete 18 provided in the embodiments of FIGS. 1, 2, 4, 5 and 6.

[Intense HMFB attack] As explained above, according to the present invention, a layer of foam mortar whose unit weight is lighter than soil is provided in the excavated hole, and the foundation is built on top of this layer of foam mortar. Because it is formed, the weight of the foundation and building is added to the ground in a ground that contains a soft ground layer at the bottom, and that the subsidence of the ground has converged and is stable compared to the current ground weight before excavation. However, the total weight applied to the ground does not increase significantly compared to before the building was constructed. Therefore, even if the ground is soft, there is no need to perform ground improvement, so the foundation can be constructed at low cost and the construction period is shortened.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the first embodiment of the invention, Fig. 2 is a schematic sectional view showing the house together, Fig. 3 is a plan view of the hole, and Fig. 4 is a sectional view showing the second embodiment of the invention. 5 is a sectional view showing a third embodiment of the invention, FIG. 6 is a sectional view showing a fourth embodiment of the invention, and FIG. 7 is a sectional view showing a fifth embodiment of the invention. be. P...hole, L...ground level, H...excavation depth, 10, IOA...bubble mortar, 12...building foundation, 13...root cutting bottom, 14. ...Kuriishi, 15
... Root cutting side, 16... Reinforcement cloth (geotextile), 17... Building, 18... Discarded concrete, 19.19A... Backfill soil, 20... Footing. Figure 1 P Square Figure 2 r ------- Huff 17 3rd U! J

Claims (1)

[Claims] A basic structure for buildings in which a layer of cellular mortar, which has a lighter unit weight than soil, is placed in the excavated hole, and the foundation is placed on top of this layer of cellular mortar.