JP3794020B2 - Dust concrete and its construction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to soil concrete for buildings such as factories, stores, warehouses, and houses constructed on soft ground and a method for constructing the same.
[0002]
[Prior art]
When building a building, the floor portion in contact with the ground is placed as soil concrete separately from the structure of the building. The soil concrete is provided directly on the ground in normal ground.
However, in soft ground where the earth strength is insufficient, as shown in FIG. 7, a support pile 20 that satisfies the support force to support the building is placed, and concrete is cast on the support pile 20 that reaches the support layer. A footing 21 is provided, a foundation beam 22 in which concrete is placed between the footings 21 is provided, a floor slab 23 in which concrete is placed on the foundation beam 22 is constructed, and this floor slab 23 is used as soil concrete. .
[0003]
However, in this construction method, not only does the construction period and cost increase due to the provision of the foundation beam 22, but also the foundation beam 22 has a structure that supports the floor slab 23. It takes time and effort to do. Thus, the floor slab structure for constructing the foundation beam 22 is troublesome to design.
Therefore, as shown in FIG. 8, a floor slab 24 is directly placed on the support pile 20 reaching the support layer to form soil concrete.
[0004]
[Problems to be solved by the invention]
However, as shown in FIG. 8, when the floor slab 24 is directly placed on the support pile 20 that reaches the support layer to form soil concrete, the support pile 20 is a foundation pile that supports the structure. Since the pile has a large bearing capacity, the pile interval is widely spaced. Thus, since the support pile (foundation pile) 20 that supports the floor slab 24 is widely spaced, the floor slab 24 is provided with double reinforcing bars 19 in order to cope with bending and cracking. It needs to be strong, such as streaking, resulting in a thicker one. For example, the thickness is 300 to 400 mm. If it is thick, the load due to its own weight of the floor slab 24 will increase, and the support pile 20 itself will need a pile capable of exhibiting a greater support force, resulting in an increase in cost.
[0005]
In view of these points, the present invention provides a soft soil with insufficient ground strength, without providing a foundation beam, and as a thin soil concrete that is provided directly on the ground in a normal ground. The present invention also provides a novel interstitial concrete that does not generate cracks and the like, and a construction method thereof.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the soil concrete of the present invention includes a small-sized soil cement column having an outer diameter of 150 to 500 mm having a thin pipe-shaped object having an outer diameter of 30 to 60 mm as a core material. The upper surface of the soil cement column group having the pipe-like material as a core material is the lower end surface of the concrete slab.
[0007]
Thus, the small-diameter soil cement column is a soil cement column having an outer diameter of 150 to 500 mm, preferably a 200 to 300 mm soil cement column , and a thin pipe-like object having an outer diameter of 30 to 60 mm is a core material at the center. Exists as. For example, a thin pipe-like material such as a steel pipe pipe having an outer diameter of 30 to 60 mm or a plastic pipe is present as a core material in the center of the soil cement column . In this way, a small-diameter soil cement column (columnar body) has a core material in the center thereof. A large number of soil cement columns in which the core material exists are formed, and concrete slabs are constructed on the soil cement column group to form soil concrete.
[0008]
As a result, in soft ground with insufficient ground strength, there is no uneven subsidence, bending, cracking, etc., even as thin interstitial concrete provided directly on the ground in normal ground.
In addition, when a thin pipe-like material such as a steel pipe pipe exists as a core material in this way, even if there is a layer (humus soil layer) in which a plant decays in the middle of a soil cement column formed on soft ground, Small pipes (such as steel pipe pipes) as a material can exist through this layer, and the presence of non-humus soil layers above and below the layer ensures that the soil cement column with the core material has sufficient support. Demonstrate power.
[0009]
Further, in the case of a soil cement column in which a solidified layer having a strength stronger than that of the soil cement, for example, a solidified layer of cement milk, exists between the core material of the pipe-like material and the soil cement layer, the core material and the cement milk The degree of integration with the solidified layer is stronger than that of the core material and the soil cement, and the degree of integration of the soil cement layer and the cement milk solidified layer is stronger than that of the core material and the soil cement. It is preferable because the strength of the soil cement in which the core material is present is increased and the supporting force is improved.
[0010]
In addition, when the upper surface of a soil cement column having a pipe-like material as a core material is bitten into the soil concrete, the soil concrete of a desired thickness must be formed on the upper surface of the soil cement column. If the soil concrete is constructed so that the upper surface of the soil cement column having the object as the core is the lower end surface of the concrete slab, the thickness of the soil concrete can be reduced.
[0011]
For this reason, the concrete in the concrete slab can be made of soil-concrete with a single-layer reinforcement structure, and can be made of thin soil-like concrete equivalent to soil-concrete provided directly on the ground in a normal ground that is not soft ground.
[0012]
In the soil concrete as described above, the distance between the centers of the soil cement columns in the soil cement column group is 0.5 m to 2 m. A particularly preferable distance between the centers of the soil cement columns is about 1 m. If soil cement columns are provided at such a small interval, the soft ground existing between the soil cement columns is limited in the amount of soil movement due to compaction due to the upward load, and it becomes close to the performance when the ground of the soft ground is improved. .
When soil concrete is constructed on a soil cement column group having a center interval of 0.5m to 2m in this way, it becomes difficult for bending and cracking due to the load applied to the soil concrete on the soil concrete column, and thin soil concrete is made. In addition, non-uniform settlement is less likely to occur.
[0013]
The length of the required soil cement column (the required depth at the bottom of the column) varies depending on the ground conditions and the diameter of the soil cement column, but the length of a general soil cement column is 2 m to 10 m. . If there is such a length, it is possible to prevent uneven settlement of the soil concrete by the peripheral friction force.
[0014]
Moreover, the construction method of soil concrete mentioned above stores the pipe-shaped thing of the outer diameter 30-60mm as a core material in the hollow rod of the small-diameter soil cement column formation apparatus of outer diameter 150-500mm. In this condition, the soil cement column is formed while the soil cement column is formed, and when a predetermined depth is reached, the small-diameter pipe-like material as the core material is left in the soil cement column. By pulling the hollow rod of the apparatus to the ground, a small- sized soil cement column having an outer diameter of 150 to 500 mm having a thin pipe-shaped object having an outer diameter of 30 to 60 mm as a core material is repeated to the center of the soil cement column. as soil cement column group interval to a large number at intervals of 0.5m~2m between single rebar on the top surface of the soil cement column group The one that set concrete by Haisuji, according to the construction method of the preferred method can be easily applying a dirt floor concrete having a desired performance.
[0015]
In addition, when lifting the hollow rod of the soil cement column forming device, it is lifted while discharging the cement milk from the hollow part of the hollow rod, and it is stronger than the soil cement between the core material of the pipe-like material and the soil cement layer When the solidified layer is formed, a soil cement column in which a solidified layer having a strength stronger than that of the soil cement is present between the core material of the pipe-like material and the soil cement layer can be obtained.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory sectional view schematically showing an embodiment of the present invention, FIG. 2 (a) is a longitudinal sectional view of a soil cement column, and FIG. 1 (b) is a transverse sectional view of the soil cement column.
[0017]
FIG. 1 schematically shows an interstitial concrete 4 in which a concrete slab 2 is constructed on a soft ground 3 on a group of small-diameter soil cement columns 1 as an example of interstitial concrete of the present invention. The small-diameter soil cement column 1 is a small-diameter soil cement column 1 having a small-diameter pipe-like object 5, for example, a steel pipe pipe, as shown in FIGS. 2 (a) and 2 (b). Between the steel pipe pipe 5 and the soil cement layer 6, which is a material, there is a cemented milk solidified layer 7 which is stronger than the soil cement.
The interstitial concrete 4 shown in FIG. 1 is a concrete slab 2 constructed so that the lower end surface of the concrete slab 2 comes to the upper surface of a soil cement column 1 having a pipe-like object 5 as a core material. As described above, the reinforcing bar 18 in the concrete slab 2 has a single-layer reinforcing bar structure. For example, the concrete slab 2 has a thickness of about 150 to 180 mm. Incidentally, in this example, the diameter of the soil cement column 1 is 250 mm, and the diameter of the steel pipe 5 is about 50 mm. The length of the soil cement column 1 is 6 m, and the distance H between the centers of the soil cement columns 1 in the soil cement column group is 1 m.
[0018]
Next, a method for constructing the soil cement column 1 will be described with reference to FIGS.
FIG. 3 is a partial cross-sectional front view showing an example of an auger as a soil cement column forming apparatus used for forming the soil cement column 1. This auger 10 is provided with a drilling blade 12, a stirring blade 13 and a co-rotation preventing blade 14 at the tip of a hollow rod (excavation rod) 11. As shown in the drawing, A small-diameter steel pipe 5 as a core material is inserted from the tip opening side, and a cement milk passage 16 is formed between the hollow rod 11 and the steel pipe 5, and the cement milk is discharged from the discharge port 15 through the passage 16. The As shown in FIG. 3, the steel pipe 5 as a core material shown in this example is provided with a plate-like body 8 at the lower end, and when inserted into the hollow rod 11, the plate-like body 8 closes the tip opening of the hollow rod 11. The cement milk supplied from the passage 16 can be reliably discharged from the discharge port 15.
[0019]
FIG. 4 is an explanatory diagram showing the steps (a), (b), (c), (d), and (e) of the soil cement column 1 using the auger 10.
First, as shown in FIG. 4A, the steel pipe pipe 5 as the core material is inserted and set in the hollow rod (excavation rod) 11 of the auger 10. This set state is as shown in FIG.
Next, as shown in FIG. 4 (b), cement milk is supplied to the passage 16 of the hollow rod 11, and the auger 10 is rotated while discharging the cement milk from the discharge port 15 and digging. Then, the ground soil excavated by the excavating blade 12 and the discharged cement milk are mixed and stirred by the action of the stirring blade 13 and the co-rotation preventing blade 14, and excavation is performed while the soil cement layer 6 is formed around the hollow rod 11. Is done. FIG. 4C shows a state where excavation is performed to a predetermined depth.
[0020]
When the soil cement layer 6 has been formed to a predetermined depth, as shown in FIG. 4 (d), cement milk is supplied from the discharge port 15 while leaving the small-diameter steel pipe 5 as the core material. When the auger 10 is reversely rotated while being discharged and gradually pulled up, a solidified layer 7 of cement milk is formed on the outer peripheral side surface of the steel pipe 5, a desired soil cement column 1 is formed, and the auger 10 is collected on the ground. . FIG. 4 (e) shows a state where the creation is completed.
[0021]
Further, when it is desired to fill the hollow portion of the steel pipe pipe 5 as a core material with cement milk, the hollow of the auger 10 coming above the upper end opening of the steel pipe pipe 5 as shown in FIG. By supplying cement milk from the passage 16 of the rod 11, the hollow portion of the steel pipe 5 is filled with cement milk.
[0022]
As described above, in the auger 10, a desired number of soil cement columns 1 are formed at predetermined intervals to form a soil cement column group, and a single-layer reinforcing bar is formed on the soil cement column group as shown in FIG. After arranging 18 bars, concrete is placed so that the lower end surface of the concrete slab 2 comes to the upper surface of the soil cement column 1 to construct a concrete slab 2 as shown in FIG.
[0023]
The following experimental example shows that the soil cement column 1 constructed as described above has an excellent supporting force.
A hollow rod (excavation rod) 11 having an outer diameter of 127 mm and a wall thickness of 15 mm is provided at the lower end of an excavation blade 12 having an outer diameter of 250 mm, and above that, the stirring blade 13 having an outer diameter of 250 mm, the excavation blade 12 and the stirring blade 13 are slightly larger. Using the auger 10 provided with the diameter co-rotation prevention wing 14, a steel pipe pipe 5 having a length of 6 m, an outer diameter of 48.6 mm and a wall thickness of 2.4 mm is inserted into the hollow rod 11, A soil cement column 1 was constructed.
This constructed soil cement column 1 has a solidified layer 7 of cement milk on the outer peripheral surface of a steel pipe pipe 5 as a core, and has an outer diameter of 250 mm and a length of 6 m in which a soil cement layer 6 exists on the outer periphery. This is a soil cement column 1.
[0024]
FIG. 5 shows performance test results of the soil cement column 1 together with a comparative example.
As shown in FIG. 5 as Example 1, the supporting force of the soil cement column 1 after 110 days from the construction was 110 KN. In addition, as shown in Comparative Example 1 in FIG. 5, the supporting force of the ground itself in which this test was performed was less than 20 KN and was a soft ground.
[0025]
The supporting force of the soil cement column 1 constructed so as to satisfy the same conditions as the soil cement column shown in the above embodiment except that the length of the steel pipe 5 is 4 m and the length of the soil cement column 1 is 4 m. As shown in Example 2 in FIG.
[0026]
For comparison, the supporting force was measured by driving only the steel pipe pipe used, but as shown as Comparative Example 2 in FIG. In addition, when a soil cement column having an outer diameter of 250 mm was formed without the presence of a steel pipe pipe as a core material, as shown as Comparative Example 3 in FIG.
[0027]
As shown above, even a small-diameter soil cement column having a small-diameter pipe-like material as a core material has a high supporting force per one, and a large number of small-diameter soil cement columns are provided at intervals. When the concrete slab 2 is constructed on the soil cement column group, even if the reinforcing bar 18 in the concrete slab 2 is a single-layer thin concrete slab 2 as shown in FIG. It can be soil concrete that does not cause uneven settlement, bending, or cracking in the weak soft ground.
[0028]
【The invention's effect】
As described above in detail, the present invention has the following effects.
(1) A small pipe-shaped object having an outer diameter of 30 to 60 mm , for example, a small- sized soil cement column having an outer diameter of 150 to 500 mm having a thin steel pipe as a core, is present at a number of intervals below, Soil concrete, in which concrete slabs are constructed on soil cement columns, is a thin soil between soft soils with insufficient ground strength, such as those provided directly on the ground in a normal ground without a foundation beam. Even with concrete, uneven settlement, bending and cracking are less likely to occur.
[0029]
(2) If the above-mentioned soil cement column is a soil cement column in which a solidified layer stronger than the soil cement exists between the core material of the pipe-like material and the soil cement layer, the support of the soil cement column The force becomes even higher, and even with the above-mentioned thin concrete concrete, uneven settlement, bending and cracking are less likely to occur, and the distance between the soil cement columns should be slightly increased compared to the case of the soil cement columns described above. It is also possible to reduce the column length and the column diameter.
[0030]
(3) The upper surface of a soil cement column having an outer diameter of 150 to 500 mm having a thin pipe-like object having an outer diameter of 30 to 60 mm as a core is made the lower end surface of the concrete slab, thereby reducing the thickness of the soil concrete. be able to.
In particular, the reinforcing bars in the concrete slab can have a single-layer reinforcement structure, and the thickness of the soil concrete can be reduced.
[0031]
(4) When the distance between the centers of the soil cement columns in the small-sized soil cement column group having an outer diameter of 150 to 500 mm having a thin pipe-like object having an outer diameter of 30 to 60 mm as a core is 0.5 m to 2 m. In addition, the thickness of the soil concrete can be reduced, and no uneven settlement, bending or cracking occurs.
In addition, when the above soil cement columns are provided at such a small interval, the soft ground existing between the soil cement columns is restricted in the amount of soil movement due to consolidation due to upward load, and the entire soft ground is improved. Close to performance. Therefore, as shown in the drawing, when soil concrete is constructed on a soil cement column group having a center interval of 0.5 m to 2 m without providing a ground improvement layer, bending due to the load applied on the soil concrete or the like Cracks are less likely to occur, and it can be made into a thin interstitial concrete, and uneven settlement is less likely to occur.
[0032]
(5) When the length of the soil cement column is 2m to 10m, the supporting force by the peripheral frictional force is increased, the thickness of the soil concrete can be reduced, and no uneven settlement, bending or cracking occurs. .
[0033]
(6) In a state where a small pipe-like material as a core material is stored in a hollow rod (excavation rod) of a soil cement column forming device, the soil cement column is formed while digging to a predetermined depth. If it has reached, the hollow pipe of the soil cement column forming device is lifted to the ground with the small pipe as the core material left in the soil cement column, so that the thin pipe is obtained. By forming a large number of small-diameter soil cement columns as the core material and placing concrete with reinforcing bars arranged in a single layer on the upper surface of the many soil cement column groups, the soil concrete having the above-mentioned performance can be easily obtained. Can be formed.
[0034]
(7) And when lifting the hollow rod of the soil cement column forming device, it is lifted while discharging the cement milk from the hollow part of the hollow rod, and the soil cement between the core material of the pipe and the soil cement layer It is possible to form a solid cement layer with stronger strength, making it a soil cement column with stronger bearing capacity, and even with thin interstitial concrete, it is easy to form interstitial concrete that is less prone to uneven settlement, bending and cracking. Can be formed. This makes it possible to slightly increase the mutual spacing between the soil cement columns, shorten the column length, reduce the column diameter, and the like as compared with the above-described soil cement column.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view schematically showing an embodiment of the present invention.
2A is a longitudinal sectional view of a soil cement column, and FIG. 2B is a transverse sectional view of the soil cement column.
FIG. 3 is a partial sectional front view showing an example of an auger as a soil cement column forming apparatus.
FIG. 4 is an explanatory diagram showing a method for forming a soil cement column using an auger in order of steps (a), (b), (c), (d), and (e).
FIG. 5 is a graph showing the performance of a soil cement column according to the present invention.
FIG. 6 is a cross-sectional explanatory view showing the main part of the soil concrete of the present invention.
FIG. 7 is an explanatory sectional view showing a conventional example.
FIG. 8 is a cross-sectional explanatory view showing another conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Soil cement column 2 Concrete slab 3 Soft ground 4 Soil concrete 5 Small-diameter pipe-like material (steel pipe)
6 Soil cement layer 7 Cement milk solidified layer 8 Plate body 10 Auger 11 as soil cement column forming device Hollow rod (hollow drilling rod)
12 Stirring blade 13 Stirring blade 14 Co-rotation preventing blade

Claims (7)

There are many small- sized soil cement columns having an outer diameter of 30 to 60 mm as a core material and having an outer diameter of 150 to 500 mm with a distance between the centers of the soil cement columns of 0.5 to 2 m. A soil-concrete characterized in that the upper surface of a soil cement column group existing below and having this pipe-like material as a core is the lower end surface of a concrete slab .   The soil concrete column according to claim 1, wherein the soil cement column has a solidified layer having a strength stronger than that of the soil cement between the core material of the pipe-like material and the soil cement layer. The interstitial concrete according to claim 1 or 2 , wherein the reinforcing bars in the concrete slab have a single-layer reinforcement structure. The soil concrete column according to any one of claims 1 to 3 , wherein the length of the soil cement column is 2m to 10m. The soil concrete according to any one of claims 1 to 4 , wherein the core material of the pipe-like material is a steel pipe pipe or a plastic pipe. Drilling while forming a soil cement column in a state where a hollow pipe of an outer diameter of 30 to 60 mm as a core material is stored in a hollow rod of a small diameter soil cement column forming apparatus having an outer diameter of 150 to 500 mm When the predetermined depth is reached, by pulling the hollow rod of the soil cement column forming device to the ground with the small diameter pipe-like material as the core material left in the soil cement column, A large number of small- sized soil cement columns having an outer diameter of 150 to 500 mm having a thin pipe-shaped object having an outer diameter of 30 to 60 mm as a core material are formed at intervals of 0.5 to 2 m between the centers of the soil cement columns. The soil cement column is a soil cement column group, in which concrete is placed by placing reinforcing bars in a single layer on the top surface of the soil cement column group. The method of construction. When lifting the hollow rod of the soil cement column forming device, it is lifted while discharging the cement milk from the hollow part of the hollow rod, and solidified with stronger strength than the soil cement between the core material of the pipe and the soil cement layer The method for constructing soil concrete according to claim 6 , wherein a layer is formed.

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