JP2020165270A - Seashell pile and ground improvement method - Google Patents

Abstract

To provide a seashell pile capable of saving resources and reducing the cost by using shells that become waste, and a ground improvement method using seashell piles.SOLUTION: Disclosed a seashell pile is formed by supplying unbaked crushed shells and microorganisms into a pile hole formed in the ground. A ground improvement method includes the steps of forming a pile hole in the ground, and supplying unbaked crushed shells and microorganisms into the pile hole; thereby, a compacted sea shell pile is constructed. Scallop shells are crashed and used as the crushed shells.SELECTED DRAWING: Figure 2

Description

The present invention relates to a shell pile utilizing the metabolic action of a shell and a microorganism (microbial reaction), and a ground improvement method using the shell pile.

Conventionally, as a countermeasure against liquefaction, a pile hole is formed in the ground requiring liquefaction countermeasures, and the ground is improved by constructing a sand pile in which the sand put into the pile hole is compacted, which is called a sand compaction pile method. An improvement method is known (see Patent Document 1).

Japanese Patent No. 4332569

Since the sand pile and the ground improvement method described above use a large amount of sand as a resource, there is a problem that resource saving and cost reduction cannot be achieved.
The present invention provides a shell pile that can realize resource saving and cost reduction by utilizing a shell that becomes waste, and a ground improvement method using the shell pile.

The shell pile according to the present invention is characterized in that it is formed by supplying crushed shells obtained by crushing unburned shells and microorganisms into a pile hole formed in the ground, and is therefore effective as a countermeasure against liquefaction. In addition, it is possible to provide a shell pile that can realize resource saving and cost reduction by using shells that become waste.
The ground improvement method according to the present invention is characterized in that a pile hole is formed in the ground, and a crushed shell product obtained by crushing unburned shells and a microorganism are supplied to the pile hole to construct a compacted shell pile. Therefore, it is possible to provide a ground improvement method that is effective as a countermeasure against liquefaction and that can realize resource saving and cost reduction using shells that are waste.
Further, in the ground improvement method according to the present invention, after forming a pile hole in the ground, a supply step of supplying crushed shells obtained by crushing unburned shells into the pile hole and microorganisms together and supplying the pile hole. Since the shell pile is constructed by alternately repeating the compaction step of compacting the crushed shell, it is effective as a countermeasure against liquefaction and saves resources by using the shell as waste. It is possible to provide a ground improvement method that can realize low cost and low cost.
In addition, since crushed scallop shells are used as the crushed shells, it is effective as a countermeasure against liquefaction, and resource saving and cost reduction using scallop shells as waste can be achieved. It is possible to provide a feasible ground improvement method.

The cross-sectional view which shows the procedure of the ground improvement method (Embodiment 1). The cross-sectional view which shows the procedure of the ground improvement method (Embodiment 1). The figure which shows the component ratio of each test piece used in Experiment 1. Numerical table showing the experimental results of Experiment 1. The graph which shows the experimental result of Experiment 1. The figure which shows the component ratio of each test piece used in Experiment 2. The graph which shows the experimental result of Experiment 2. Numerical table and graph showing the experimental results of Experiment 2.

As shown in FIGS. 1 and 2, the shell pile 5X according to the first embodiment was formed by supplying a crushed shell product obtained by crushing an unfired shell and a microorganism into a pile hole formed in the ground 1. It is a thing.
Further, in the ground improvement method using the shell pile 5X according to the first embodiment, a pile hole is formed in the ground 1, and a crushed shell product obtained by crushing an unburned shell and a microorganism are supplied to the pile hole for tightening. A hardened shell pile 5X was constructed.
That is, instead of the sand pile, a shell pile 5X was constructed.

The crushed shells are fragments formed by crushing (splitting) shells to almost the same size, coarse particles formed by crushing shells into coarse particles with a large particle size, and crushing shells into powder. Refers to the powder formed in the above.

The unbaked shell is an inorganic-organic complex composed of about 95% by mass of an inorganic component and about 5% by mass of an organic component. The inorganic component is calcium carbonate, and the organic component is composed of a protein called conchiolin and chitin. Will be done.
The structure of the unfired shell is such that an organic sheet exists as a binder between the plate-shaped calcium carbonate layers, and the calcium carbonate layer and the organic sheet are bonded to each other.

Therefore, by supplying the unburned crushed shell and the microorganism to the pile hole formed in the ground 1, carbon dioxide (calcium ion) generated by the metabolic action of the microbial and the crushed shell in the unburned shell. Calcium carbonate is precipitated between the particles of the crushed shell by the mineralization reaction that reacts with calcium ions other than calcium carbonate, and the bond between the particles of the crushed shell (between the calcium carbonate layers) becomes stronger, and the crushed shell It is considered that the shell piles 5X are formed by being bonded to each other and solidified.
Furthermore, carbon dioxide produced by the metabolic action of microorganisms reacts with calcium ions present in the soil or supplied to the soil (mineralization reaction), and carbonates precipitated between soil particles. It is thought that the soil will solidify.

For example, when the shell pile 5X is formed by supplying unburned crushed shells and microorganisms to the pile holes formed in the consolidated land 1 that requires liquefaction countermeasures, the shear resistance of the consolidated ground 1 As the force is improved, the shell pile 5X becomes a porous body with many gaps between the crushed shells, and has excellent water permeability and water resistance. Therefore, the pore water pressure around the shell pile 5X decreases. It is considered that the effect of stabilizing the subsidence of the viscous ground 1 at an early stage and reducing the amount of consolidation settlement can be obtained.
Further, when the shell pile 5X is formed by supplying unburned crushed shell shells and microorganisms to the pile holes formed in the sandy ground 1 that requires liquefaction countermeasures, the sandy ground 1 It is considered that the relative density of the sandy land 1 is increased and the shear strength of the sandy land 1 is improved.

Specifically, the shell pile 5X may be formed through the steps shown in FIGS. 1 (a) to 1 (c) and 2 (a) and 2 (b).

For example, as shown in FIG. 1, a driving device 3 that rotates the casing pipe 2 and the casing pipe 2 around the central axis of the casing pipe 2 and raises and lowers the casing pipe 2 along the central axis of the casing pipe 2. Using a machine equipped with a scallop shell crushed product 5 and an input port 4 for charging the yeast liquid into the casing pipe 2, (1) drilling step, (2) scallop shell crushed product and yeast liquid described later. The shell pile 5X as shown in FIG. 2 is constructed through the loading step, (3) compaction step, and (4) shell pile construction step.

(1) Drilling Step As shown in FIG. 1A, the casing pipe 2 is rotated and lowered in the ground 1 to reach the tip of the casing pipe 2 to a predetermined depth to form a pile hole.
(2) Scallop shell crushed product and yeast solution charging step The scallop shell crushed product 5 obtained by crushing unbaked scallop shells is charged into the casing pipe 2 through the charging port 4, and then shown in FIG. 1 (b). As described above, the casing pipe 2 is pulled up to discharge the scallop shell crushed product 5 into the pile hole formed in the ground 1, and the scallop is scalloped from the tip of the casing pipe 2 via the supply pipe (not shown) attached to the casing pipe 2. The yeast solution is supplied to the crushed shell product 5.
The yeast solution may be prepared, for example, by dissolving yeast (microorganism) and glucose (nutrient source metabolized by the microorganism) in pure water.
(3) Compaction step The scallop shell crushed material 5 discharged into the pile hole is compacted in the pile hole by moving the casing pipe 2 up and down, thereby expanding the diameter of the pile as shown in FIG. 1 (c). Part 5A is formed.
(4) Seashell pile construction step (2) Seashell crushed and yeast solution injection step and (3) Compaction step are alternately repeated to extend from a predetermined depth of the ground 1 to the ground surface, FIG. 2 (a). As shown in FIG. 2B, a plurality of shell piles 5X are constructed, and a plurality of shell piles 5X are further constructed according to the ground improvement range of the ground 1.

According to the shell pile 5X and the ground improvement method using the shell pile 5X according to the first embodiment, it is effective for liquefaction countermeasures, and resource saving and cost reduction using shells as waste are achieved. It is possible to provide a feasible shell pile 5X and a ground improvement method using the shell pile 5X.

In the above, the scallop shell crushed product 5 and the yeast liquid are supplied to the pile hole together, but the scallop shell crushed product 5 and the yeast liquid may be supplied to the pile hole separately. For example, the scallop shell crushed product 5 is supplied to the scallop hole, and the scallop shell crushed product 5 is compacted to supply the yeast solution to the scallop shell crushed product 5, or after the yeast solution is supplied to the scallop hole, the scallop The crushed scallop shell 5 may be supplied to the pile hole to compact the crushed scallop shell 5.

Further, a mixture prepared by mixing scallop shell crushed product, yeast solution and earth and sand may be supplied to the pile hole.
In this case, as the earth and sand, for example, mountain sand, red earth, or the like as used in the experiment described later may be used.

Moreover, although yeast was exemplified as a microorganism, other microorganisms may be used.
Moreover, although glucose was exemplified as a nutrient source metabolized by microorganisms, other nutrient sources may be used.

Further, as long as the scallop shell crushed product contains water, it is not necessary to supply water.
Further, when the soil of the ground 1 contains water, nutrients and the like, only unfired scallop shell crushed products and microorganisms may be supplied to the pile holes.

Further, as described above, it is preferable to supply unbaked scallop shell crushed products, microorganisms, and nutrient sources such as glucose metabolized by the microorganisms to the pile holes, but it is not always necessary to supply the nutrient sources. I do not care. For example, it may be sufficient to simply supply the cultured and activated microorganisms and the unbaked crushed shells.

Further, if calcium nitrate or calcium chloride containing calcium ions is supplied to the pile hole, the mineralization reaction is promoted, so that a more preferable shell pile and a ground improvement effect can be obtained.

Further, if a pH adjuster is supplied to the pile hole, a mineralization reaction in which carbonate ions and calcium ions generated by a microbial reaction react can be promoted, and a more preferable shell pile and a ground improvement effect can be obtained. it can.
That is, it is said that the pH environment of the soil for accelerating the mineralization reaction in which carbonate ions and calcium ions generated by the microbial reaction react with each other is preferably pH 8 to 9, and the above-mentioned minecal or caucal Alternatively, by maintaining the pH environment of the soil at pH 8 to 9 by using a mixed fertilizer in which minekal and caucal are mixed, the mineralization reaction can be promoted, and a more preferable shell pile and ground improvement effect can be obtained. be able to.

Further, in the above, an example in which a scallop shell crushed product is used as the uncooked shell crushed product has been shown. You may use it.

In the present invention, "supplying crushed shells and microorganisms obtained by crushing unburned shells to the pile holes formed in the ground" means that the pile holes are a mixture of crushed shells and microorganisms. Supplying, or supplying crushed shells and microorganisms to the pile holes at the same time or separately.

Experiment 1
An experiment was conducted to confirm the difference in the supporting strength of the solidified shell crushed material formed by the difference in the size of the crushed shell material.
As the crushed shell, an unfired crushed scallop (scallop) shell was used.

As shown in FIG. 3, the following test specimens were used.
-The test body 1 was a test body in which 8 g of calcium nitrate + 150 ml of yeast solution was supplied to 350 g of crushed scallop shells having coarse particles. 350 g of the coarse-grained scallop crushed product is 80 to 90% of the scallop shell crushed product having a particle size of 10 mm to 2 mm + 10 to 20% of the scallop shell crushed product having a particle size of 0.85 mm to 0.1 mm. As the crushed scallop shell, the trade name "scallop chip" and the product of Aomori Eco Cycle Industry Cooperative Company were used.
-The test body 2 was a test body in which 8 g of calcium nitrate + 150 ml of yeast solution was supplied to 350 g of crushed scallop shells having medium particles. 350 g of the medium-particle crushed scallop shell is 55 to 60% of the crushed scallop shell having a particle size of 2 mm to 0.85 mm + 40 to 45% of the crushed scallop shell having a particle size of 0.85 mm to 0.005 mm. As the crushed scallop shells of the medium particles, the trade name "Scallops and Genki" and the product of Aomori Eco Cycle Industry Cooperative Company were used.
-The test body 3 was a test body in which 8 g of calcium nitrate + 150 ml of yeast solution was supplied to 400 g of powdered scallop shell crushed product. The powdered scallop crushed product (400 g) is 100% scallop shell crushed product having a particle size of 0.106 mm to 0.005 mm. Made by Eco Cycle Industry Cooperative Company.
The yeast solution 150 ml was prepared by dissolving 8 g of yeast and 8 g of glucose in pure water.
Further, each of the test bodies 1, 2 and 3 was prepared by spreading scallop shell crushed material on the bottom of a predetermined container to a depth of 20 mm and then pouring 150 ml of yeast solution.
Then, each test body 1, 2, 3 is left in a room temperature environment (temperature 30 ° C., humidity 60%) for several days, and every day, the support strength of each test body 1, 2, 3 is increased. The situation was measured.
The support strength was measured by a Yamanaka hardness tester.

-Experimental results As can be seen from Fig. 4; Fig. 5, each of the test bodies 1, 2 and 3 was solidified, and in particular, the test body 2 in which the yeast was supplied to the medium-sized scallop shell crushed product was supported after 3 days. A solidified shell crushed product having a strength of 117.1 N / mm ² and a high supporting strength could be obtained.

From the experiment, it can be proved that the crushed scallop shell can be solidified by supplying 150 ml of the yeast solution prepared by dissolving 8 g of yeast and 8 g of glucose in pure water to the crushed scallop shell. It was.

As in the experiment, the reason why the crushed scallop shells could be solidified was firstly that they were produced by the metabolic action of the microorganisms by supplying the crushed shells of unbaked shells with microorganisms. Calcium carbonate is precipitated between the particles of the crushed shell by the mineralization reaction in which the carbon dioxide (carbonate ion) reacts with calcium ions other than calcium carbonate in the crushed shell, and the particles of the crushed shell It is considered that the bond between (calcium carbonate layers) became stronger, and the crushed shells were bonded to each other to form a solidified crushed shell.
Second, in the experiment, the crushed shells of unbaked shells were supplied with microorganisms and calcium nitrate, so that calcium ions in the calcium nitrate and carbon dioxide produced by the metabolic action of the microorganisms were supplied. By promoting the mineralization reaction that reacts with and depositing calcium carbonate between the particles of the crushed shell, the bond between the particles of the crushed shell (calcium carbonate layer) becomes stronger, and the crushed shells become stronger. It is considered that a solidified body of crushed shell was formed by combining and solidifying.

In particular, like Test Body 2, the scallop crushed product has medium particles (for example, the scallop shell crushed product having a particle size of 2 mm to 0.85 mm is 55 to 60% + the scallop shell crushed product having a particle size of 0.85 mm to 0.005 mm). When it is 40 to 45%), the gaps between the medium particles of the scallop shell crushed product become dense, the bond between the calcium carbonate layers becomes stronger, and a solidified body of the scallop shell crushed product having high supporting strength is formed. Conceivable.
Further, like the test body 1, the scallop crushed product has coarse particles (for example, scallop shell crushed product having a particle size of 10 mm to 2 mm 80 to 90% + scallop shell crushed product having a particle size of 0.85 mm to 0.1 mm 10 to 20). %), It is considered that the gap between the coarse particles of the scallop crushed scallop was large, so that the bond between the calcium carbonate layers was weakened and the supporting strength of the formed scallop crushed solidified body was not increased.
Further, when the scallop shell crushed product is powder particles (for example, the scallop shell crushed product having a particle size of 0.106 mm to 0.005 mm is 100%) as in the test body 3, the scallop shell crushed product itself is powdery particles. It is probable that the supporting strength of the formed crushed shell material did not increase because the supporting strength of the scallop was weak.

Experiment 2
An experiment was conducted to confirm the difference in soil improvement effect based on the difference in soil and the difference in the size of crushed shells to be supplied.

As shown in FIG. 6, the following test specimens were used.
1. 1. The test piece name "Yamasago" was a test piece obtained by supplying 8 g of calcium nitrate + 150 ml of yeast solution + a pH adjuster (0.5 g of Keikal + 19.5 g of Minekal) to 400 g of mountain sand.
2. The test piece name "red clay" was a test piece obtained by supplying 350 g of red clay with 8 g of calcium nitrate + 150 ml of yeast solution + pH adjuster (0.5 g of caical + 12.0 g of minecal).

3. 3. The test piece name "Yamasago + Hochu" was a test piece in which 400 g of mountain sand was supplied with 40 g of crushed medium-grain scallop shells + 8 g of calcium nitrate + 150 ml of yeast solution + pH adjuster (0.5 g of Keikal + 19.5 g of Minekal). ..
4. The test piece name "mountain sand + sail powder" was a test body in which powdered scallop shell crushed product 40 g + calcium nitrate 8 g + yeast solution 150 ml + pH adjuster (Keikaru 0.5 g + Minekal 1.5 g) was supplied to 400 g of mountain sand. ..
5. The test piece name "mountain sand + sail rough" supplied 380 g of mountain sand with 80 g of crushed scallop shells in the form of coarse grains (fragment) + 8 g of calcium nitrate + 150 ml of yeast solution + pH adjuster (0.5 g of Keikal + 5.5 g of Minekal). It was used as a test body.

6. The test piece name "red clay + sail powder" was prepared by supplying 200 g of red clay with 100 g of powdered scallop shell crushed product + 8 g of calcium nitrate + 150 ml of yeast solution + pH adjuster (0.5 g of caical + 12.0 g of minecal).
7. The test piece name "red clay + sailing" was a test piece in which 200 g of red clay was supplied with 100 g of crushed medium-grain scallop shells + 8 g of calcium nitrate + 150 ml of yeast solution + pH adjuster (0.5 g of caical + 12.0 g of minecal).
8. The test piece name "red clay + sail rough" is a test body in which coarse grain (fragment) scallop shell crushed product 100 g + calcium nitrate 8 g + yeast solution 150 ml + pH adjuster (Keikaru 0.5 g + Minekal 12.0 g) is supplied to 200 g of red clay. And said.

The mountain sand had a particle size of about 5 mm to 0.125 mm, and the trade name "mountain sand", manufactured by Nakajima Gravel, was used.
The red soil (clay soil) had a particle size of about 0.074 mm to 0.005 mm, and was used under the trade name "Yamasago" and manufactured by Nakajima Gravel.
As the crushed scallop shell, a crushed scallop shell obtained by crushing an unbaked scallop shell was used.
The medium-grain crushed scallop shells are 55-60% crushed scallops with a particle size of 2 mm to 0.85 mm + 40-45% crushed scallop shells with a particle size of 0.85 mm to 0.005 mm. The name "Scallops are fine", made by Aomori Eco Cycle Industry Cooperative Company.
The powdered scallop crushed product was 100% scallop shell crushed product having a particle size of 0.106 mm to 0.005 mm, and the trade name "scallop marker", manufactured by Aomori Eco Cycle Industry Cooperative Company was used.
The coarse-grained (fragment-like) scallop crushed product is 80 to 90% of the scallop shell crushed product having a particle size of 10 mm to 2 mm + 10 to 20% of the scallop shell crushed product having a particle size of 0.85 mm to 0.1 mm. , The product name "scallop chip", made by Aomori Eco Cycle Industry Cooperative Company was used.
As the above-mentioned Minekal, which is a converter lime fertilizer as a pH adjuster, the trade name "Kumiai Minekal", manufactured by Sangyo Shinko Co., Ltd. was used.
The above-mentioned silicic acid fertilizer as a pH adjuster used the trade name "Kumiai Silicic" and manufactured by Murakashi Lime Industry Co., Ltd.
Further, 150 ml of yeast solution was prepared by dissolving 8 g of yeast and 8 g of glucose in pure water.
A test piece using mountain sand is prepared by spreading mountain sand or mountain sand and crushed scallop shells on the bottom of a predetermined container to a depth of 40 mm, and then pouring 150 ml of yeast solution. did.
A test piece using red clay (clay) is prepared by spreading red clay or red clay and crushed scallop shells on the bottom of a predetermined container to a depth of 10 mm, and then pouring 150 ml of yeast solution. did.
Then, each test piece was left in a room temperature environment (temperature 30 ° C., humidity 60%) for 7 days, and the supporting strength of each test piece was measured every day.
The support strength was measured by a Yamanaka hardness tester.

-Experimental results Fig. 7 shows the results of changes in the supporting strength of the test specimens that did not supply the crushed shells, that is, the specimen names "mountain sand" and "red clay" in Fig. 6 over time. Shown.
As can be seen from the graph shown in FIG. 7, sufficient support strength was not obtained with the test specimens "mountain sand" and "red soil", which were only supplied with yeast solution without supplying crushed shells, and were expected. No soil improvement effect was obtained.

Specimen "mountain sand + sail (medium)", test body "mountain sand + sail (powder)", test body "mountain sand + sail (rough)" in which crushed shells of different sizes were supplied to mountain sand. , And the test body "red soil + sail (powder)", the test body "red soil + sail (medium)", and the test body "red soil + sail (rough)", in which crushed shells of different sizes were supplied to the red soil. Figures 8 (a) show the numerical values showing the results of the transition of the support strength obtained with time, and FIGS. 8 (b) and 8 (c) show the graphs showing the results of the transition of the support strength.

As can be seen from FIGS. 8 (a) and 8 (b), the test body "mountain sand + sail (middle)", the test body "mountain sand + sail (powder)", and the test body "mountain sand + sail (rough)" On the 5th day, an excellent soil improvement effect was obtained in which the supporting strength reached 117.1 N / mm ² .

Further, as can be seen from FIGS. 8 (a) and 8 (c), the test body "red soil + sail (powder)" is remarkably excellent in that the supporting strength reaches 480.6 N / mm ² on the third day. It was found that the soil improvement effect was obtained.

The first reason why the above-mentioned soil improvement effect was obtained is that carbon dioxide (calcium ion) produced by the metabolic action of microorganisms by supplying unburned crushed shells and microorganisms to the soil. Calcium carbonate is precipitated between the particles of the crushed shell by the mineralization reaction that reacts with calcium ions other than calcium carbonate in the crushed shell, and the bonds between the particles of the crushed shell (calcium carbonate layers) are formed. It is considered that the crushed shells became stronger and the crushed shells were bonded to each other to form a solidified crushed shell.
Secondly, in the experiment, since calcium nitrate was supplied, the mineralization reaction in which calcium ions in calcium nitrate react with carbon dioxide produced by the metabolic action of microorganisms was promoted, and calcium carbonate was promoted between the particles of the crushed shell. It is presumed that the precipitation of calcium nitrate strengthened the bonds between the particles of the crushed shells, and the crushed shells were bonded to each other to form a solidified crushed shell.
Thirdly, carbon dioxide produced by the metabolic action of microorganisms reacts with calcium ions existing in the soil or calcium ions in calcium nitrate supplied to the soil (mineralization reaction) to produce soil particles. It is considered that the soil was solidified by the carbonates precipitated between them.
That is, when unburned crushed shells and microorganisms are supplied to the soil, it is considered that the soil improvement effect is improved by the synergistic effect of the solidification of the crushed shells and the solidification of the soil.

Further, the mountain sand has a particle size of 5 mm to 0.125 mm, whereas the powdered scallop shell crushed product has a particle size of 0.106 mm to 0.005 mm, and the medium grain scallop shell crushed product has a particle size. The crushed scallop shells having a size of 2 mm to 0.005 mm and coarse grains (fragments) have a particle size of 10 mm to 0.1 mm.
That is, in the experiment, since the scallop shell crushed product having a particle size smaller than that of the mountain sand is supplied, the scallop shell crushed product enters between the mountain sand particles, and the bond between the mountain sand particles becomes stronger. It is presumed that the soil became stronger and had a high supporting strength.

The red clay has a particle size of 0.074 mm to 0.005 mm, whereas the powdered scallop shell crushed product has a particle size of 0.106 mm to 0.005 mm, and the medium grain scallop shell crushed product has a grain size. The crushed scallop shells having a diameter of 2 mm to 0.005 mm and coarse grains (fragments) have a particle size of 10 mm to 0.1 mm.

That is, the test body "red clay + sail (powder)" has a size corresponding to the particle size of the soil particles of red clay and the particle size of the powder particles of the powdered scallop shell crushed product. In other words, since the particle size of the soil particles of red soil and the particle size of the powder particles of the powdered scallop shell crushed product are almost the same (high), the fine spacing between the particles can be equalized. It is considered that the carbonates formed by the mineralization reaction were precipitated and hardened at the minute intervals between the equalized particles, so that the entire red soil was solidified as one and the soil had a remarkably high supporting strength.
That is, from the experiment, it was found that the supporting strength of the soil can be improved by supplying the soil with crushed scallop shells and microorganisms having a size corresponding to the size of the soil particles in the soil.

The powdery scallop shell crushed product used in the experiment has a particle size of 0.106 mm to 0.005 mm, which is compared with the medium-grain scallop shell crushed product and the coarse-grained (fragment-like) scallop shell crushed product. Since it is presumed that a large amount of powder having a particle size smaller than the upper limit of 0.074 mm of the particle size of red soil is contained, powdery scallop shell crushed matter easily enters between the particles of red soil, and between the particles of red soil. It is presumed that as the bond became stronger, the entire red soil became one and solidified, resulting in a soil with extremely high supporting strength.

In particular, by adopting a method of supplying unfired crushed shells and microorganisms having a size corresponding to the size of soil particles of the soil to the soil, a remarkably excellent soil improvement effect capable of significantly improving the supporting strength can be obtained. It turned out to be obtained.
For example, supplying powdered scallop shell crushed material having a particle size of 0.106 mm to 0.005 mm to red soil which is clay having a particle size of about 0.074 mm to 0.005 mm, that is, grains of soil particles in the soil. By supplying crushed scallop shells with a size smaller than the diameter and microorganisms to red soil (soil), powdered scallop crushed products can easily enter between the particles of red soil, and the bond between the particles of red soil becomes stronger. Therefore, it was found that a remarkably excellent soil improvement effect capable of significantly improving the supporting strength can be obtained.

On the other hand, in the test body "red clay + sail (medium)" and the test body "red clay + sail (rough)", the particle size of the soil particles of red clay and the diameter of the scallop shell crushed material are significantly different.
That is, the distance between the red clay and the crushed scallop shell is large and the arrangement is disjointed. For this reason, it is probable that the bond between the red clay and the crushed scallop shell was weakened, and the supporting strength could not be obtained.

Therefore, from the experiment, it was found that the supporting strength of the soil can be improved by supplying the soil with crushed scallop shells having a size smaller than the particle size of the soil particles of the soil and microorganisms.

In other words, when the soil is clayey soil, the supporting strength of the clayey soil can be improved by supplying powdered scallop shell crushed material and microorganisms to the clayey soil, and the soil improvement effect can be achieved. Was found to be obtained.

1 Ground, 5 crushed shells, 5X shell piles.

Claims (4)

A shell pile characterized in that it is formed by supplying crushed shells obtained by crushing unfired shells and microorganisms into a pile hole formed in the ground. A method for improving the ground, characterized in that a pile hole is formed in the ground, and a shell pile obtained by supplying crushed shells obtained by crushing unburned shells and microorganisms to the pile hole and compacting the pile hole. After forming a pile hole in the ground, a supply step of supplying the crushed shell crushed unburned shell and microorganisms together to the pile hole and compaction of the crushed shell material supplied to the pile hole. A ground improvement method characterized in that shell piles are constructed by alternately repeating steps. The ground improvement method according to claim 2 or 3, wherein a crushed scallop shell is used as the crushed shell.

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