JPH0784742B2 - Basic method for soft ground - Google Patents

Description

Description: TECHNICAL FIELD The present invention mainly relates to a foundation construction method for constructing a foundation of a house on ultra-soft ground.

2. Description of the Related Art Conventionally, a raft foundation method has been known as a method for preventing ground subsidence in such soft ground. For example, in Japanese Examined Patent Publication No. 48-22086, a steel pipe is buried in a raft shape at a position deeper than the groundwater level of soft ground, and the load of a structure is supported by utilizing the buoyancy force received by this steel pipe. Japanese Patent Publication No. 57-7254 discloses a method of burying a perforated concrete pipe below the water pipe which is a structure when the water pipe is buried. Further, Japanese Patent Laid-Open No. 56-67013 discloses a method for stabilizing the ground in which two or more layers of soil pipes and concrete pipes are embedded orthogonally to each other.

Problems to be Solved by the Invention As described above, in soft ground, settlement occurs due to the load of the building, etc., and at this time, uneven settlement occurs due to the load difference of each part of the building, and therefore the foundation cracks and the building It will result in the terrain.

The following means are effective as means for preventing such uneven settlement.

． It reduces the ground's own weight, which prevents the ground from sinking due to its own weight.

． Reinforce and strengthen the ground itself to withstand shear and tensile failure.

． Disperse the load acting on the ground as much as possible so that a large load is not applied locally.

Furthermore, since this kind of soft ground contains a large amount of water, it is also necessary to take a moisture-proof structure so that the humidity due to evaporation of this water does not rise under the floor.

However, in the conventional raft foundation method,
In the invention of Japanese Patent Laid-Open No. 48-22086, since the buoyancy of the pipe is used, even if the above points can be satisfied to some extent, it cannot be said that and are sufficient, and effective subsidence prevention cannot always be achieved. There are drawbacks.
Further, the invention of Japanese Examined Patent Publication No. 57-7254 is aimed at the drainage effect by the pipe, and neither of the above is sufficient. Furthermore, the same applies to Japanese Patent Laid-Open No. 56-67013, and in any case, it cannot be effective in preventing uneven settlement of a building. Furthermore, in any of the above cases, sufficient measures against moisture are not taken.

In view of such conventional drawbacks, the present invention provides
The purpose of the present invention is to provide a basic construction method for soft ground, which satisfies all of the above requirements and is also capable of obtaining a moistureproof effect under the floor.

Means for Solving the Problems In order to achieve the above object, in the present invention, first, synthetic resin pipes (2) and (3) whose both ends are closed are provided with a plurality of upper layer side pipes (3) and lower layer side pipes (3). Two or more layers are arranged so that the side pipe (2) forms a lattice shape. The upper layer pipe (3) and the lower layer pipe (2) are tightly connected to each other at their intersections. Between the pipes that are tightly bound and arranged in this way, an aggregate with a large particle size that creates a gap such as gravel or crushed stone with a diameter of 45 mm or more is filled,
From the bottom of the lower layer pipe (2) to the upper layer pipe (3)
The aggregate layer (7) is formed up to the upper surface of the
Build a foundation (4) spaced above.

Action In the above structure, the pipes (2) and (3) are closed at both ends, which prevents water from entering the pipes (2) and (3) and keeps the hollow state. Contributes to weight reduction. Also, since it is a synthetic resin,
It will be lighter. The pipes (2) and (3) arranged in two or more layers so as to form a lattice pattern with each other,
By tightly connecting each of these pipe layers, the load of the building and the structural foundation is distributed over the entire pipe layers, and a large load is prevented from acting locally. Furthermore, the aggregate between the pipes filled according to the invention has a diameter of 45 mm.
We use a large particle size that creates the above-mentioned gravel, crushed stone, etc. gaps, which prevents water from infiltrating upward from the lower layer due to the capillary phenomenon, and provides a moisture-proof effect under the floor, and this bone The material layer (7) itself is prevented from becoming heavy by containing water.

Examples Next, the construction method of the present invention will be described based on Examples.

In FIG. 1, first, the ground is excavated, and on the excavated ground surface (1), hollow synthetic resin pipes (2) (3) ... At this time, as shown in FIG. 2, one of the lower layer pipe (2) and the upper layer pipe (3) is the lower layer pipe (2).
(2) ... are arranged in the same direction as the cloth foundation (4) constructed above it, and the upper pipes (3) (3) ... are arranged in a direction transverse to this cloth foundation (4), and both are arranged. They are orthogonal to each other to form a grid. Furthermore, these upper pipes (3) (3)
... and the lower pipes (4) (4) ... are tightly connected to each other at the intersections by the numbered wires (5), etc., whereby the pipes (2) (3) ... Let the body form.

At this time, the depth D from the bottom surface of the footing (6) portion of the foundation (4) to the lower surface of the lower pipe (2), that is, the bottom surface of the pipe layer was drawn downward from both end corners of the lower surface of the footing (6). Depth 2B to the intersection point X of the shear fracture lines l and l
On the other hand, B / 2 <D <2B. This 2B is equal to twice the width B of the footing portion (6). As described above, it has been confirmed that by making the depth D to the bottom surface of the pipe layer deeper than 2B, the resistance to shear failure acting on the ground is increased. . Further, the upper layer side pipe (3) arranged in the transverse direction of the cloth foundation (4) has its end portion projected more outward than the footing portion (6), and the protruding length L is L> As a result, the load acting while expanding the ground from the foundation (4) is more firmly supported by these, and these pipes (2) (3) ... strengthen and strengthen the ground itself like Yasu concrete rebar. Then, it acts as a strong resistance against the destruction of the ground.

Next, the gaps between the pipes (2), (3) ... Installed as described above are filled with aggregates having a large particle diameter such as gravel and crushed stone having a diameter of more than 45 mm to form the pipe layer. An aggregate layer (7) of the same level is formed. The aggregate layer (7) is filled between the bottom surface of the lower pipe (2) and the upper surface of the upper pipe (3). Since the aggregate layer (7) made of gravel or crushed stone having a large grain size has a large gap between the aggregates, it prevents water from rising from the ground due to the capillary phenomenon, and the ground itself Not only becomes heavy by containing water, but also exhibits a moisture-proof effect that prevents moisture from rising under the floor. In addition, when an earthquake occurs, so-called liquefaction damage in which liquefied water and sand rise below the floor often occurs, but the aggregate layer (7) is
It also has a function of flowing the water and sand horizontally along the aggregate layer (7) without directly rising upward and discharging the water and sand outside the building.

Next, a moisture-proof sheet (8) such as a non-woven fabric is laid on the upper surfaces of the upper pipe (3) and the aggregate layer (7) laid as described above. The moisture-proof sheet (8) has a function of making the moisture-proof effect more complete and enhancing the effect of discharging water and sand to the outside of the building at the time of the earthquake. As described above, the upper layer pipe (3) and the lower layer pipe (2) are in close contact with each other and tightly bonded to each other. Therefore, due to the rising pressure of water and sand as described above, these pipes (2) )
(3) is prevented from moving, which further enhances the effect of discharging it outside the house.

Finally, a good quality soil is embedded in the upper part of the moisture-proof sheet (8) to construct the cloth foundation (4).

FIG. 3 shows an installation range of the pipes (2) and (3). For example, in a two-story house as shown in FIG. 6a) (6b), the cloth foundation (6a) (6b) is installed on the whole surface surrounded by a solid shape, while on the first floor only where the load is small, that cloth foundation (6c) It is placed only in the part. That is, the load is large, so
The pipes (2) and (3) should be installed over a wide area in the area where there is a high possibility of sinking, and the area where the pipe should be installed should be reduced for the area where the load is small and the possibility of sinking is low. By doing so, it is possible to prevent uneven settlement as much as possible, and the amount of pipes used is reduced to reduce the cost accordingly.

As described above, according to the present invention, since the pipe is made of synthetic resin, it is light, and since both ends of this pipe are closed to prevent water or earth and sand from entering therein, the pipe is always kept inside. Since it is held in a hollow state to reduce the weight of the ground, the effect of preventing settlement is great, and in addition to this, an aggregate with a diameter of 45 mm or more that creates a large gap between the pipes Since it is filled with, it is possible to make the ground more hollow, and it is possible to prevent the aggregate part etc. from becoming heavy due to water content due to the rise of water due to the capillary phenomenon, and the ground can be made lighter. .

Further, the upper-layer pipe and the lower-layer pipe, which are orthogonal to each other, are tightly connected to each other at their intersections and integrated, so that the load of the structure is distributed to the pipe without being locally applied. Therefore, it is possible to economically perform the construction without causing a local large load to cause uneven settlement, and without requiring the pipe to have a thick wall or a large diameter.

Furthermore, since the aggregate layer prevents the rise of water due to the capillary phenomenon, a moisture-proof effect under the floor can be obtained.

As described above, the present invention realizes as lightly as possible the most important point of the soft ground countermeasure method, strengthens and strengthens the ground itself, distributes the load acting on the ground, and prevents moisture under the floor. Since it also has an effect, it can exert an excellent effect as a measure against soft ground.

Further, since the pipe is made of synthetic resin, there is no fear of corrosion as compared with a steel pipe or the like.

Furthermore, since a gap is provided between the aggregate layer in which the pipe is arranged and the foundation, the load is not transmitted to this pipe,
Since it is dispersed and transmitted, there is no need to increase the diameter of the pipe itself or increase the strength by making it thick, and it can be economically implemented.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a base portion showing an embodiment of the present invention, FIG. 2 is a plan view of a main portion when a pipe portion is viewed from above, and FIG. 3 is supported by the foundation of the present invention. FIG. 3 is a schematic vertical sectional view showing the entire building. (2) (3) ... pipe, (4) ... cloth foundation, (6) ...
… Bottom of base (footing), (7) …… Aggregate layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-50-9214 (JP, A) JP-A-50-78104 (JP, A) JP-A-56-67013 (JP, A)

Claims (1)

[Claims] 1. A synthetic resin pipe whose both ends are closed is arranged in two or more layers such that a plurality of upper layer pipes and a plurality of lower layer pipes form a lattice, and these upper layer pipes and lower layer pipes are arranged. The bottom of the pipe on the lower layer side is filled with aggregates with a large grain size that tightly connect the pipes with each other at their intersections and create gaps such as gravel and crushed stone with a diameter of 45 mm or more between the pipes. A foundation method for soft ground, characterized in that an aggregate layer is formed from the top to the upper surface of the pipe on the upper layer side, and a foundation is constructed above the aggregate layer at intervals.