JPH06257135A - Columnar ground improving body and building method thereof and sheathing wall - Google Patents

Abstract

PURPOSE:To improve the bending strength and the compression strength of a columnar ground improving body by mixing the metal reinforcing material, which consists of wire rods and plate materials having flexibility, in the soil cement for building a columnar improving body and a sheathing wall to be stood in the soft ground, and filling an excavation hole with this mixture, and solidifying it. CONSTITUTION:Solidification agent such as cement and an aggregate 3, which consists of steel wires and steel plates having swelled or bent hook parts, are mixed in the excavation soil S, and excavation holes 11 are filled with this mixture. In the case of improving the ground, these excavation holes 11 are excavated with a specific space, and in the case of forming a sheathing wall 2, the excavation holes 11 are excavated so that the diameter thereof are overlapped with each other slightly. The mixture of the cement and the aggregate 3 is agitated by a screw auger 10 or the like at the time of back filling, or kneaded on the ground separately. The soil cement is placed into the excavation holes 11 and solidified. A columnar body strong against bending and compression is thereby obtained at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a columnar improved body which is built upright in soft ground and a method of constructing the same, and further, by arranging the columnar improved body in a columnar structure, an underground portion of a structure is formed. The present invention relates to a retaining wall that is built to enclose a space for use.

[0002]

2. Description of the Related Art Conventionally, this type of columnar improvement body is formed by mixing a cement-based solidifying material into excavated soil, and is formed into a columnar shape (or a pile shape) by being solidified in an excavation hole. It is a thing. They are built in columns and are used as earth retaining walls (yamadome walls) as shown in FIGS. 15 and 16, and as shown in FIG. It is distributed and arranged in a shape, etc. and used for improving soft ground.

As a concrete construction method of the columnar improvement,
When used for small-scale or medium-scale soil retention, there is a so-called SMW method (soil mixing wall) method or DSP (dry soil pile) method. In addition,
In addition to the above, the main pile lateral sheet pile construction method, sheet pile construction method, underground continuous wall construction method, etc. are well known as soil retaining methods, but for small to medium-scale soil retaining methods, their workability, reliability, and cost. From the aspect, the column array method by the SMW method or the DSP method is becoming mainstream.

The SMW method uses a construction machine having a single or multiple screw auger and a stirring mechanism,
At the same time as excavating the ground with a screw auger, a slurry solidified material such as cement milk mixed with bentonite is injected into the excavation hole together with air, etc., and subsequently, the excavated soil and the solidified material are kneaded by a stirring mechanism, and soil cement This is a method of forming a columnar improved body in the soil.

[0005] The DSP method is a method of using a powder solidifying material without using water in contrast to the SMW method, and after excavating the ground with a screw auger, the discharged excavated soil and the ground of dry powder are used. This is a method in which a solidifying material is mixed, the hole is backfilled again, and the screw auger is inverted and compacted.

[0006]

The columnar improvement of soil cement has relatively high durability against compressive force, but as a property of cement, it is not very durable against bending force. Therefore, for example, When it is used as a retaining wall, as shown in FIG. 15, a columnar improvement 3 having one or several H-shaped steel materials 32 for reinforcement against earth pressure.
1 or embedded in all of the columnar improvement bodies 31.

As described above, the structure in which the reinforcing H-shaped steel material 32 is buried entails a high material cost and also requires labor for transportation, handling and burying work.

Particularly in small-scale or medium-scale soil retaining, the H-shaped steel material used therefor has a cross-sectional dimension of, for example, 3
Many of 50 × 175 × 4.5 × 9 are used, but this steel material has a weight per meter of 36.5 kg,
When using the retaining wall at intervals of 90 cm, the retaining wall is 1 m ²
The amount of steel per unit is 40 kg, which accounts for most of the cost.

In order to effectively utilize the strength of the soil cement, the present invention makes it possible to easily and inexpensively improve the strength of the pillar-shaped improvement body itself made of soil cement, and thereby to improve the soil retaining wall using the pillar-shaped improvement body. In the case of building, the purpose is to omit the H-shaped steel material for reinforcement altogether or to greatly reduce it, thereby reducing the building cost and improving the work efficiency.

[0010]

The invention according to claim 1 is
In the columnar improvement of the ground obtained by solidifying the excavated soil with a solidifying material, a large number of flexible elongated reinforcing materials are mixed in a dispersed state.

According to the second or third aspect of the present invention, in the columnar improved body according to the first aspect, a metal wire material or a metal plate material having a bulged or bent hook portion is used as a reinforcing material. Is a columnar improvement of the ground.

According to a fourth aspect of the present invention, which is a method for constructing the above-mentioned columnar improved body, which is applied to a so-called DSP construction method, the ground is excavated in a cylindrical shape and the excavated soil is discharged to the ground, and the discharge is performed. A method of constructing a columnar improvement body for ground, characterized by mixing a solidifying material and a large number of flexible elongated reinforcing materials in excavated soil, and filling the excavated hole again to compact the soil.

According to a fifth aspect of the present invention, which is a construction of the above-mentioned columnar improved body and is applied to a so-called SMW method, at the same time as excavating the ground, a slurry solidifying material,
A large number of elongated reinforcing materials having flexibility are injected into the excavation hole, and subsequently, the excavated soil, the slurry-like solidifying material and the large number of the reinforcing materials are kneaded in the excavation hole. It is a method of constructing a columnar improvement body of the ground.

According to a sixth aspect of the present invention, there is provided an earth retaining wall using the columnar improved body according to the first aspect, wherein the columnar improved bodies in which a reinforcing material is mixed in a dispersed state are arranged in a columnar arrangement. It is a characteristic retaining wall.

[0015]

In the columnar body, a number of elongated reinforcing members made of a flexible wire or plate, for example, metal having a hooked portion are mixed in a dispersed state. As a result, the reinforcing material made of metal, etc. resists pulling due to bending force from the outside, and serves as a tie. The restraint improves the strength of the columnar body itself.

Therefore, when building a retaining wall,
It is possible to significantly reduce the number of H-shaped steel materials or eliminate them.

Since the reinforcing member made of metal or the like has flexibility and has a catching portion, when these are mixed with soil cement or the like and stirred, the elasticity and the catching action make it uniform and disjointed. Are dispersed in different postures.

[0018]

1 and 2 show an earth retaining wall 2 using a columnar body 1 to which the present invention is applied. First, the structure of the columnar body 1 alone will be described. The columnar improved body 1 is
It is built upright in the ground 4, and cement-based solidifying material and a large number of elongated metal reinforcing materials 3 are mixed in the excavated soil in a dispersed state. The metal reinforcing material 3 is substantially uniformly dispersed in the columnar body 1, and the mixing ratio thereof is
About ³⁰ to 60 kg is mixed in 1 m ^{3 of} soil.

FIG. 7 shows an example of the metal reinforcing material 3, and a steel wire having a thickness of about 0.3 to 1.0 m and a length of 3 cm to 8 cm is used as the material. The metal reinforcing member 3 made of this steel wire is bendable, and both ends thereof are bent in a stepwise manner as the catching portions 6.

An example of the entire structure of the retaining wall will be described. Figure 1
In, the soil retaining wall 2 is constructed by arranging a large number of the columnar improved bodies 1 in the ground in a columnar shape, and adjacent columnar improved bodies 1 are formed so as to overlap each other little by little. .

FIG. 13 shows an overall plan view of an example of the construction of the retaining wall 2. The retaining wall 2 is constructed in a rectangular shape so as to surround the entire circumference of the space T for forming the underground portion of the structure. Has been done.

A method of constructing the columnar improved body 1 by the DSP method will be described with reference to FIGS. 3 to 5.

In FIG. 3, a screw auger 10 having an auger diameter of 30 cm to 80 cm is used as a construction machine,
By the normal rotation X1 of this screw auger 10, the ground 4
At the same time as forming the columnar excavation hole 11, the excavated soil S is taken out around the upper surface of the excavation hole 11 by utilizing the rotation of the screw auger 10.

In FIG. 4, excavated soil S is mixed with a powdery cement-based solidifying material A and a large number of metal reinforcing materials 3 are provided.
And knead. In this case, kneading may be performed on the ground surface, or a kneading device may be installed and kneading may be performed therein.

In FIG. 5, the mixed excavated soil S formed by mixing the solidifying material A and the large number of reinforcing materials 3 as described above is backfilled in the excavated hole 11 by utilizing the reverse X2 of the screw auger 10. It is compacted and the columnar improvement 1 is built in place.

When constructing the earth retaining wall 2 as shown in FIG. 13, first, the columnar improvement bodies 1 are successively constructed in the ground at intervals of every other one, and then the above construction is carried out. The columnar improved bodies 1 are newly built so as to overlap the existing columnar improved bodies 1 on both sides little by little between the formed columnar improved bodies 1.

By adopting such a building sequence, when the excavation hole 11 for the columnar body 1 is formed by the screw auger 10, the screw auger 10 is set on the existing columnar body 1 adjacent thereto. No worries about tilting.

When all of the columnar improvement bodies 1 of FIG. 13 have been built and hardening has been completed for a certain period of time or for a certain number of days, the inside of the earth retaining wall 2 is excavated as shown in FIG. A space T is secured.

A method of forming the columnar improved body 1 by the SMW method will be described with reference to FIG. As a construction machine, a machine equipped with three rotary shafts 12 having excavation and stirring functions is used. Each rotating shaft 12 is provided with a cement milk injection port 13 and an air injection port 14 at the tip end thereof, and is provided with a screw auger 10, and an intermediate portion thereof is provided with a rotary stirring mechanism 15 including a large number of stirring blades 17. And a single drive source 19 causes the transmission mechanism 18 to
The two rotary shafts 12 can be rotated simultaneously.

The cement milk injection port 13 has a rotary shaft 12
The air injection port 14 is connected to an appropriate air supply source via an air passage in each rotating shaft 12 by being connected to the inside of the mixing device 21 via a passage in the inside and a connection hose 20.

The mixing device 21 stores cement milk M in which cement having bentonite is dissolved in water and a large number of metal reinforcing materials 3 mixed therein.

Each rotating shaft 12 is rotated to rotate the screw auger 1.
In the process of excavating by 0, each tip injection port 13, 1
Cement milk M containing the metal reinforcing material 3 and air are jetted from the No. 4 to the tip portion of the excavation hole, and the excavated soil S and the cement milk M are slurried and mixed by the stirring blade 17.

After kneading, the construction machine is pulled out and dried.

[0034]

[Another embodiment]

(1) FIG. 8 shows one mode before the use of the metal reinforcing member 3 made of the steel wire of FIG. 7 by using a water-soluble adhesive.
A large number of them are adhered, and for example, the mixing device 2 of FIG.
1 can be put in the same shape as that shown in FIG. 8, and after the addition, the adhesive is dissolved and naturally decomposed into individual substances and dispersed.

(2) FIG. 9 shows a modified example of the metallic reinforcing member 3, in which bulging portions are formed as the catch portions 6 at both ends of the steel wire. As a method of manufacturing the metal reinforcing member 3 in FIG. 9, for example, a wire rope after use is unwound and reused, and the wire is manufactured by gas fusing to a certain size as indicated by an arrow. To be done. When the gas is melted, the bulging portion is automatically formed.

(3) The metal reinforcing member 3 shown in FIG. 10 has a structure in which a steel wire is formed in a ring shape, and the curved portion serves as the catch portion 6.

(4) The metallic reinforcing member 3 shown in FIG. 11 has a structure in which a steel wire is formed in a teardrop shape, and the curved portion serves as the catching portion 6.

(5) The metal reinforcing member 3 shown in FIG. 12 is a thin iron plate having a width of 0.8 cm to 2 cm, a length of 5 cm to 10 cm, and a thickness of 0.3 mm to 1.0 mm. And is formed in a corrugated shape in order to include the catch portion 6.

(3) As an application of the columnar improvement body 1, in addition to using it for the earth retaining wall, it can be used for improving the ground on the foundation construction surface of the building as shown in FIG. That is, a large number of columnar improvement bodies 1 are built on a ground of a predetermined size so as to be spaced at appropriate intervals and distributed over the entire foundation surface, and the compaction is performed thereon.

(4) As the reinforcing material, glass fiber or carbon fiber having a relatively high rigidity can be used instead of the metal wire.

[0041]

As described above, according to the present invention, (1) in a columnar improvement body of the ground in which excavated soil is solidified by a solidifying material, an elongated reinforcing material made of a flexible steel wire or an iron plate Since a large number of 3 are mixed in a dispersed state, the strength of the columnar improved body 1 against bending and compression is significantly improved.

That is, since the reinforcing member 3 made of metal or the like resists the tensile stress due to the bending force applied to the columnar body 1, the allowable bending stress degree is increased from double to several times. Even with respect to the compressive stress applied to the body 1, the reinforcing material 3 made of metal or the like serves as a tie and restrains the movement of the soil, so that the allowable compressive stress level is also increased from double to several times.

(2) When the soil retaining wall 2 is constructed by improving the strength of the columnar body 1 itself as described above, the number of reinforcing steel frames such as H-shaped steel material is greatly reduced, Alternatively, it can be eliminated, and a reduction in construction cost and an improvement in work efficiency can be achieved.

(3) Further, since the reinforcing member 3 made of a slender metal or the like, which is made of a steel wire or an iron plate, which is flexible and has the bulging or bent catching portion 6, is used. The mixing work of 3 is easy, and
It is easy to disperse, and it can be mixed into excavated soil or the like without forming voids between the excavated soil and solid matter, and the quality of the columnar improved body 1 can be sufficiently ensured.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view of an earth retaining wall to which the present invention is applied.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a vertical cross-sectional view showing an excavation and discharge stroke in the method according to claim 4 of the present application.

FIG. 4 is a vertical sectional view showing a mixing step in the method according to claim 4 of the present application.

FIG. 5 is a vertical sectional view showing a backfill compaction step in the method according to claim 4 of the present application.

FIG. 6 is a vertical sectional view showing a method according to claim 5 of the present application.

FIG. 7 is a side view of a single metallic reinforcing member.

FIG. 8 is a plan view showing one form before using the metal reinforcing material.

FIG. 9 is a side view showing a modified example of the metal reinforcing member.

FIG. 10 is a side view showing a modified example of the metal reinforcing member.

FIG. 11 is a side view showing a modified example of the metal reinforcing member.

FIG. 12 is a side view showing a modified example of the metal reinforcing member.

FIG. 13 is a plan view showing an example of the entire structure of the retaining wall.

FIG. 14 is a plan view showing an arrangement example when a columnar improvement body is applied to ground improvement.

FIG. 15 is a horizontal sectional view showing a conventional columnar improved body and a retaining wall.

16 is a sectional view taken along line XVI-XVI of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Columnar improvement body 2 Soil retaining wall 3 Metal reinforcing material 6 Catch portion A Solidifying material S Excavated soil M Cement milk (slurry solidifying material)

Claims (6)

[Claims] 1. A columnar improvement of the ground obtained by solidifying excavated soil with a solidifying material, wherein an elongated reinforcing material having flexibility is used.
A columnar improvement of the ground characterized by being mixed in a large number of dispersed states. 2. The columnar improvement body for ground according to claim 1, wherein a metal wire rod having a bulging or bent hooking portion is used as the reinforcing material. 3. A columnar improvement body for a ground according to claim 1, wherein a metal plate material having a bulging or bent catching portion is used as the reinforcing material. 4. The ground is excavated into a cylindrical shape, and the excavated soil is discharged to the ground, and the discharged excavated soil is mixed with a solidifying material and a large number of flexible elongated reinforcing materials, and the excavated hole is re-exposed to the excavation hole. A method for constructing a columnar improved body of the ground, characterized by backfilling and compacting. 5. Simultaneously with excavation of the ground, a slurry-like solidifying material and a large number of flexible elongated reinforcing materials are injected into an excavation hole, and subsequently, excavated soil, a slurry-like solidifying material and a large number of A method of constructing a columnar improved body for ground, comprising kneading the reinforcing material in an excavation hole. 6. An earth retaining wall, characterized in that the columnar improvement according to claim 1 is arranged in columns.