JP3431905B2 - Improved soil structure of sandy soil layer and improvement method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the subsidence and deformation of the ground at the time of an earthquake by placing a reinforcing material such as a plate-like plastic material in the sandy soil layer around the foundation, and prevents the excessive clearance. The present invention relates to a ground improvement technique for promptly dissipating water pressure to prevent liquefaction.

[0002]

2. Description of the Related Art When a sandy soil layer is subjected to repeated shearing force due to earthquake motion, the pore water pressure rapidly increases, and as a result, the soil loses shearing force, causing a liquefaction phenomenon that behaves as if it were a liquid. It is known to express.

As conventional techniques for suppressing such a liquefaction phenomenon, those for compacting the ground (compacting method), those for discharging underground water (drain method), and those for solidifying the ground with a solidifying material (solidifying method) ), Those that lower the groundwater level (groundwater level lowering method), those that surround the ground with sheet piles or concrete walls exist. Of these, the compaction method causes severe vibration and noise during construction, and it tends to be avoided to apply the existing structure to the surrounding ground. Further, the solidification method is not the best means because the cost of the solidifying material used for it is high. The method of lowering the groundwater level is difficult to maintain and the cost is high, and the method of enclosing the ground with sheet piles has the drawback that the construction cost is high. From such a background, it can be said that the drainage method is a meaningful basic means for preventing liquefaction in both construction and effects.

[0004]

However, if the conventionally known draining methods are applied as they are, since these methods merely bury them in the sandy soil layer at appropriate intervals, the increase in excess pore water pressure is reduced. However, there was a problem that the shearing force of the ground could not be sufficiently strengthened against lateral flow and the like just by performing the above.

Further, since the drain material simply buried is driven with one end or both ends being in a free end state, the drain material itself is displaced in the ground following the repeated shear stress of seismic motion. The function of absorbing the lateral flow of the ground was not perfect. This means that an increase in excess pore water pressure cannot be prevented, and the liquefaction phenomenon was not fundamentally avoided.

The present invention has been made in view of the above-mentioned problems, and the object thereof is to follow the advantages of the construction method of the reinforcement material over the conventional drain construction method, but by improving this, the sand can be more surely obtained. It is an object of the present invention to provide a ground structure and an improved construction method capable of preventing the ground deformation of a soil layer and suppressing the liquefaction phenomenon.

[0007]

In order to achieve the above object, the present invention is an improved ground structure in which a plurality of reinforcing materials are cast in a sandy soil layer, and the reinforcing material has flexibility. It is a long plate, and a plurality of them are placed in the sandy soil layer at equal intervals until their lower ends reach the non-liquefied ground so that their wide surfaces are facing or orthogonal to each other , and their upper ends are other reinforcing materials. Continuous with top
After being tied, a means of burying with crushed stone or the like and placing in a softly restrained state was used. For example, the upper end of the reinforcement is
After binding tightly to a lid, etc., burying it with crushed stone etc. for soft restraint
To do. By this means, the upper end of the reinforcement is restrained more firmly.
can do. The lower end of the reinforcing material is fixed to the ground by reaching the non-liquefied ground, but the lower end may be fixed by another positive means such as an anchor (Claim 3) (Claim 3). 2). According to these means, the reinforcing material itself is not displaced by the repeated shear stress of the earthquake motion, and the excess pore water pressure can be surely dissipated. Therefore, it is possible to effectively prevent deformation such as subsidence and lateral flow of the ground.

Further, in claim 4, the reinforcing member is constituted by a long plate-shaped plastic board or a high-tensile-material-integrated plastic board. According to this means, since the reinforcing material is a material having rigidity and elasticity, it is possible to prevent the ground deformation due to the rigidity and to secure the lateral ground reaction force by the elasticity.

Further, in the fifth aspect, the means for forming the outer surface of the reinforcing material in a non-smooth form is used. According to this means, the frictional resistance between the reinforcing material and the surrounding sandy soil layer is increased,
The deformation of the ground can be restrained more effectively.

Further, in the sixth aspect, means for using a plastic drain in which the outer periphery of the water passage formed in the inner longitudinal direction is adhered or wound with a water-permeable coating is used. According to this means, the excess pore water pressure generated by the repeated shear stress of the earthquake motion can be promptly dissipated, and the rise of the excess pore water pressure can be prevented.

Further, according to the seventh aspect, by adopting the means of placing the reinforcing materials in a mixed manner between the foundations of the building, the foundation itself of the building can be provided with the improved ground structure.

Further, in the eighth aspect, since the reinforcing material also serves as the foundation of the building, there is an advantage that the conventional foundation such as a pile can be omitted in addition to the same effect as in the seventh aspect.

Further, according to a ninth aspect, as a ground improvement method for a sandy soil layer, a plurality of reinforcing materials are cast into the sandy soil layer, the lower end of the reinforcing material is fixed to the non-liquefied ground, and then the upper end thereof is fixed. The other
After connecting with the upper end of the reinforcing material of the
The method of bundling was used. By this means, it is possible to obtain the improved ground structure of the sandy soil layer having the above-mentioned function.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an improved ground structure according to a first embodiment of the present invention, where 1 is a building, 2 is a building foundation, and 3 is a plastic reinforcing material. In addition, 4 shows a sandy soil layer, 5 shows a non-liquefied ground.

The reinforcing member 3 has a width of 10 m as shown in FIG.
As shown in FIG. 3, it has a long plate shape with a length of m and a length of 200 mm, and as shown in FIG.
Plural pieces are placed at equal intervals with a pitch of about 0 mm. Further, the reinforcing material 3 has its lower end fixed to the non-liquefied ground 5 by an anchor 6 or the like, and the upper end thereof is connected by a connecting tool 7 such as a geogrid or geotextile. By embedding with crushed stone 8, the upper end of the reinforcing material 3 is restrained.

More specifically, as shown in FIG. 4, the restraint structure at the upper end of the reinforcing member 3 is provided with a substantially inverted T-shaped width stopper 3a at the upper end and a wedge-shaped anchor 6 at the lower end. Reinforcement material 3 is cast, and lower geogrid 3b and rubble stone 3c are laid on width stop metal fitting 3a in this order (Fig. (A)).
The upper geogrid 3d and the geotextile 3e are laid in that order, the pressure support plate 3f is fixed to the width stop fitting 3a (FIG. 2B), and then the uppermost layer is covered with soil. According to this structure, the upper end of the reinforcing member 3 can be restrained and fixed in a state where the influence of the seismic motion is small.
Further, since the anchor 6 described here has a wedge shape, it has a strong pull-out resistance and can firmly restrain the lower end of the reinforcing material 3. That is, it is suitable as a structure capable of maximizing the function of the reinforcing member 3.

According to the improved ground structure of the present invention constructed as described above, since the reinforcing material 3 is placed with the upper end and the lower end constrained, the subsidence caused by liquefaction,
Ground deformation such as lateral flow can be suppressed. Moreover, since the reinforcing member 3 is made of a material having a certain degree of rigidity and elasticity such as plastic, it is possible to secure a lateral ground reaction force.

In the above-mentioned embodiment, an example suitable for the case where the improved ground is retroactively applied around the existing building 1 is shown. However, in the case of a newly built building, the site ground of the building 1 itself It is also possible to add the same improved ground structure to. That is, as shown in FIG. 5, by placing the reinforcing material 3 in a mixed manner between the foundations 2, an improved ground structure can be added to the ground itself where the building 1 is located. Further, as shown in FIG. 6, it is possible to provide the reinforcing member 3 with the function of the foundation directly. In this case, the conventional foundation can be omitted, and the workability is excellent.
Moreover, the cost is also advantageous.

Further, in the above-described embodiment, the structure in which the reinforcing members 3 are driven in the same direction over a plurality of rows has been described. However, as shown in FIG. 7, the wide surfaces of the reinforcing members 3 are arranged in a direction orthogonal to each other. Placing it is also effective. This is because the reinforcing material 3 can effectively work in all the action directions of the earthquake motion.

Depending on the structure of the building 1 and the properties of the sandy soil layer, an improved ground structure having only the parallel array group shown in FIG. 3 or an orthogonal array group having only the orthogonal array group as shown in FIG. It is also possible to adopt an improved ground structure or to combine a parallel array group and an orthogonal array group as shown in FIG.

FIGS. 10 and 11 show further other embodiments in which the improved ground structure of the present invention is applied to the rear side of the retaining wall 9 or the dam 10, respectively, and as shown in FIG. A first improved structure 11 is provided along the retaining wall 9 or the dam 10, and the first improved structure 1 is provided.
The second improved structures 12 and 13 are provided perpendicularly to 1. According to this embodiment, it is possible to reduce the ground horizontal force by suppressing the lateral flow.

In any of the above-mentioned embodiments, the reinforcing material 3 is used.
Although a long plate-shaped plastic board was used as the above, it is more preferable to use a reinforcing material having a drain function. That is, as shown in FIG. 13, it is preferable to use a plastic drain 16 in which a plurality of water passages 14 are formed in the inner longitudinal direction and the outer periphery thereof is adhered with a water-permeable coating 15. According to the plastic drain 16, in addition to suppressing the lateral flow and securing the lateral ground reaction force described above, the excess pore water pressure generated by the repeated shearing force of the seismic motion is promptly dissipated to increase the excess pore water pressure. It is possible to prevent and suppress the subsidence of the ground.

Further, it is preferable that the outer surface of the reinforcing material has a non-smooth shape. Specifically, the outer surface is provided with a satin-like deformation, or a synthetic fiber woven fabric or the like is used as the water-permeable coating 15. By making the outer surface of the stiffener non-smooth in this way, it is possible to more effectively restrain the deformation of the ground during an earthquake due to the frictional resistance between the stiffener and the surrounding sandy soil layer. The generation of water pressure can be kept small.

[0024]

As described above, according to the present invention, since a plurality of reinforcing members are placed around the foundation with the upper and lower ends restrained, ground subsidence caused by liquefaction and lateral Ground deformation such as flow can be suppressed. Further, by adopting a plastic drain as the reinforcing material, the excess pore water pressure generated by liquefaction can be promptly dissipated, the excess pore water pressure can be prevented from rising, and the subsidence and deformation of the ground can be suppressed to a small extent.

[Brief description of drawings]

FIG. 1 is a sectional view conceptually showing an improved ground structure according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a reinforcing material.

FIG. 3 is a plan view of the improved ground structure.

FIG. 4 is an explanatory view showing a procedure for placing a reinforcement

FIG. 5 is a sectional view conceptually showing an improved ground structure according to another embodiment.

FIG. 6 is a sectional view conceptually showing an improved ground structure according to still another embodiment.

FIG. 7 is a plan view showing another example of placing reinforcement members

FIG. 8 is a plan view showing an improved ground structure according to another embodiment.

FIG. 9 is a plan view showing an improved ground structure according to still another embodiment.

FIG. 10 is a sectional view conceptually showing an improved ground structure according to still another embodiment.

FIG. 11 is a sectional view conceptually showing an improved ground structure according to still another embodiment.

FIG. 12 is a plan view of an improved ground structure applied to another embodiment.

FIG. 13 is a plan view showing a plastic drain having another structure.

[Explanation of symbols]

1 building 2 foundation 3 Reinforcement material 4 Sandy soil layer 5 Non-liquefied ground 6 anchor 7 connector 8 crushed stone 9 retaining wall 10 dam 11.12.13 Improved structure 14 waterways 15 Water-permeable coating 16 plastic drain

Front Page Continuation (72) Inventor Takao Hongo 3-28-65 Kamokogahara, Higashinada-ku, Kobe-shi, Hyogo Prefecture (72) Inventor Shogo Kuboshima 2-4-25-2 Uenohigashi, Toyonaka City, Osaka Prefecture (72) Invention Person Tadaaki Nomura 52-3 Terada Imabori 52-3 Terada, Joyo-shi, Kyoto Prefecture (72) Inventor Takeshi Asada 4-chome 32-32 Kamitsutsui-dori, Chuo-ku, Kobe City, Hyogo Prefecture (72) Shoichi Yamazaki Chidori, Tarumi-ku, Kobe City, Hyogo Prefecture Kugaoka 3-chome 22-40 (72) Inventor Yoshihiro Mizoguchi 507-6 Rano, Noguchi-cho, Kakogawa-shi, Hyogo Prefecture (72) Inventor Masashi Odera 366-13 Takahata-cho, Nara-shi (56) References Special Kaihei 7-207652 (JP, A) JP 3-81410 (JP, A) JP 10-131209 (JP, A) JP 10-325136 (JP, A) JP 63-89731 ( (58) Fields surveyed (Int.Cl. ⁷ , DB name) E02D 3/10 103 E02D 27/34

Claims (9)

(57) [Claims] 1. An improved ground structure in which a plurality of reinforcing materials are cast in a sandy soil layer, wherein the reinforcing material has a flexible long plate shape, and its wide surfaces face each other or are orthogonal to each other. As shown in the figure, a plurality of piles are placed in the sandy soil layer at equal intervals until their lower ends reach the non-liquefied ground, and their upper ends are connected to the upper ends of other reinforcements.
An improved ground structure for a sandy soil layer, which is characterized by being buried and softly constrained by crushed stone . 2. The improved ground structure for a sandy soil layer according to claim 1, wherein the lower end of the reinforcing material is fixed to the non-liquefied ground. 3. The improved ground structure for a sandy soil layer according to claim 2, wherein the lower end of the reinforcing material is fixed to the non-liquefied ground by an anchor. 4. The improved ground structure for a sandy soil layer according to claim 1, 2 or 3, wherein the reinforcing material is made of plastic or high tension material integrated plastic. 5. An outer surface of the reinforcing material has a non-smooth shape.
The improved ground structure of the sandy soil layer according to any one of 1 to 4 . 6. The sand according to claim 1, wherein the reinforcing material has a drainage function by adhering or winding a water-permeable filter on the outer periphery of the water passage formed in the inner longitudinal direction. Improved soil structure of soil layer. 7. The improved ground structure for a sandy soil layer according to any one of claims 1 to 6 , wherein reinforcements are mixed and placed between foundations of a building. 8. claims 1 also serves as a basis for reinforcement buildings
The improved ground structure of the sandy soil layer according to any one of 6 to 6 . 9. A plurality of reinforcing materials are cast on a sandy soil layer so as to form a group wall, the lower ends of the reinforcing materials are fixed to the non-liquefied ground, and the upper ends thereof are used as the upper ends of other reinforcing materials. After connecting, crush
A ground improvement method for sandy soil layers, which is characterized by being buried by stones and softly restrained .