JP2001059217A - Method and material for ground improvement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attenuate influence to an existing structure or the like to enable ground improvement by filling a ground improvement material composed of hard-baked unslaked lime powder and granules, calcium sulfate-based hardened powder and granules, and silicificated metamorphic alunite-based powder and granules in drill holes of the ground. SOLUTION: A ground G is drilled and a ground improvement material is filled to construct a pile 1. The ground improvement material is composed by mixing three components of 10-60 wt.%, of hard-baked unslaked lime powder and granules, 3-30 wt.% of calcium sulfate-based hardened powder and granules, and 6-60 wt.% of silicificated metamorphic alunite-based powder and granules or an additional appropriate quantity of inorganic material such as blast-furnace granulated slag, coal ash, etc. The hydration expansion is delayed by unslated lime burned in a high temperature and the ground improvement material is granulated to increase the reactivity, and ettringite is generated to increase the strength and form a hardened body 2 expanded in the ground G. In this way, influence to an existing structure or the like due to an abrupt hydration expansion action is prevented to compact the ground G and form the hardened body 2 and enhance the ground strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement material and a ground improvement method used for ground improvement for improving soft ground and preventing liquefaction.

[0002]

2. Description of the Related Art Generally, a viscous ground, a peat ground, or the like having a high water content, or a loosely deposited sand ground having a problem of liquefaction is called a soft ground. When constructing a structure, there are problems such as the ground's bearing capacity for the structure, subsidence of the ground, and the like. For this reason, when constructing a structure on soft ground, the ground is improved before the construction. Such ground improvement methods include the quick lime pile method, which is a method for expanding the material in the ground to increase the strength of the surrounding ground, and is mainly used as a measure to prevent liquefaction, and compacts sand piles in the ground. There is a sand compaction pile construction method, which is a method of building while building.

[0003]

However, the quicklime pile method is a method of forming a composite ground by consolidating the surrounding ground by expansion action due to the reaction of digestion and absorption of quicklime, but the existing structure by expansion of quicklime is used. Inevitably impact on. That is, since the reaction of quicklime occurs instantaneously, the expansion force is strong and it is difficult to avoid adverse effects such as displacement of existing structures and increase in earth pressure. Therefore, the workability is not sufficiently satisfactory.

[0004] In addition, pile material made of quicklime is treated as a temporary material because it has no strength by itself.
The strength of the material itself put into the ground cannot be expected, and the durability of the material over a long period of time is poor.
Therefore, an increase in liquefaction resistance and strength of the entire ground cannot be expected. Furthermore, the soil improvement method using cement or lime as a main raw material increases the pH in the ground, and in some cases, adversely affects the quality of groundwater.

[0005] On the other hand, in the sand compaction pile method in which a sand pile is formed in the ground instead of the method based on the expansion of the material, vibration and noise for compacting the sand pile may adversely affect existing structures and the surrounding environment. There is. Also,
The pitch of the ground improvement body is smaller than that of the construction method based on the expansion of the material, which may be uneconomical.

[0006] Therefore, the present invention provides a method for increasing the liquefaction resistance and strength of the ground as a whole without affecting the existing structure and the surrounding environment.
It is an object to provide a ground improvement material and a ground improvement method excellent in workability.

[0007]

SUMMARY OF THE INVENTION In order to solve these problems, the present invention relates to a ground improvement material which expands and hardens by reacting with moisture in the ground to improve the ground. An object of the present invention is to provide a ground improvement material comprising calcined lime powder, calcium sulfate-based hardened powder, and silicified modified alumite-based powder.

The mixing ratio of the hard-burned quick lime powder, the calcium sulfate-based hardened powder, and the silicified modified alunite-based powder is such that the hard-burned quick lime powder has a mixing ratio of 10 % To 60%, the calcium sulfate-based hardened powder 3% to 30%, and the silicified modified alumite-based powder 6% to 6%.
0%, and the total is preferably 100%.

The ground improvement material preferably contains an inorganic material, and more preferably, the inorganic material is granulated blast furnace slag or coal ash. further,
The total of the mixing ratio of the hard-burned quick lime powder, the calcium sulfate-based hardened powder, the silicified modified alumite-based powder, and the inorganic material is 100% by weight, and The mixing ratio of the quicklime powder, the calcium sulfate-based hardened powder, and the silicified modified alumite-based powder is 10% to 60% for the hard-burnt quicklime powder, and the calcium sulfate-based hardened powder. It is preferable that the content of the granules is 3% to 30% and the content of the silicified modified alumite-based powder is 6% to 60%, and the shortage is the mixing ratio of the inorganic material.

[0010] That is, the present invention provides an expansion effect of hard-burned quicklime powder by digestion and water absorption, and hard-burned quicklime powder, calcium sulfate-based hardened powder, silicified modified alunite-based powder, and It is a ground improvement material that has self-hardening properties due to the hardening action caused by the reaction of the components of the inorganic material and also develops strength.

[0011] In addition, hard burned lime powder, calcium sulfate-based hardened powder, silicified modified alumite-based powder, and a ground improvement material containing an inorganic material in these components can be used in the ground. A ground improvement method for improving the ground by forming a hardened body that has expanded to a certain extent can also be used.

That is, the present invention provides a hard-burnt quick-lime powder that produces a delayed-action swelling action, a calcium sulfate-based hardened powder, a silicified modified alumite-based powder, a granulated blast furnace slag, and By using a ground improvement material that expresses self-hardening and strength because it contains inorganic materials such as coal ash,
This is a ground improvement method that can effectively improve the ground without affecting existing structures and the like due to a sudden increase in earth pressure.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of the ground improvement material according to the present invention will be described below. The ground improvement material according to the present invention is not limited to those described in the present embodiment.

[Soil Improvement Material] The soil improvement material according to the present invention comprises hard-burned quicklime powder, calcium sulfate-based hardened powder, and silicified modified alumite-based powder. It contains an inorganic material in addition to the components.

[0015] The hard-burnt quick-lime powder granules which can be used in the present invention are those obtained by subjecting the calcining treatment to a temperature in the range of 1100 to 1500 ° C, more preferably 1100 to 1300 ° C. Quicklime is produced by calcining and decomposing limestone, and the hydration rate of the produced quicklime varies depending on the conditions of this calcination.For example, when calcination is performed at a high temperature, the hydration rate, that is, digestion / water absorption The swelling effect of the reaction slows down. For this reason, the firing process is performed at 1100
By performing the treatment in a high temperature range of 1500 ° C., it is possible to make the expansion effect of the ground improvement material of the present invention slow. The calcined calcined lime obtained by calcining in this temperature range has a consumption of 4N hydrochloric acid of 150 ml or less as a 3-minute value after the start of titration by the rapid lime coarse lime titration method of the Japan Lime Association. Here, if the calcination temperature is lower than 1100 ° C., the activity of quicklime is too high, the hydration rate is increased, and a rapid expansion action occurs. On the other hand, if the firing temperature is higher than 1500 ° C., the activity of quicklime decreases too much, and the swelling action becomes small, which is not suitable.

It is preferable to use a powder fluid obtained by pulverizing hard calcined lime powder granulated in such a temperature range to a particle size of 15 mm or less. By making the powdery material as described above, the reactivity of the hard-burnt quick lime whose activity has been reduced by the treatment at a high temperature can be increased, and a hydration rate suitable for construction can be obtained. In this way, by making the inflation action a slow-acting type, it is possible to suppress the effect on existing structures and the like caused by the instantaneous inflation action.

The calcium sulfate-based hardened powder of the present invention can be used without any particular limitation as long as it is derived from calcium sulfate or a mixture containing calcium sulfate. For example, natural gypsum, chemical gypsum, flue gas desulfurization gypsum, gypsum phosphate, gypsum hydrofluoric acid, gypsum such as waste gypsum board, natural gypsum, dihydric gypsum, anhydrous gypsum, etc.
Examples of the chemical gypsum include dihydrate gypsum, anhydrous gypsum, and hemihydrate gypsum. These calcium sulfate-based hardened particles can be used alone or in combination of two or more.

The silicified modified alunite-based powder of the present invention is not particularly limited as long as it contains a silica component. Thus, by containing the silica component, more pozzolanic reactions are caused,
Since it contributes to the production of ettringite together with the hard-burned quicklime powder and the calcium sulfate-based hardened powder, the self-hardening property of the ground improvement material of the present invention can be enhanced. Therefore, the ground improvement material of the present invention is hardened by the pozzolanic reaction and the generation of ettringite to develop strength, and thus can achieve long-term durability.

Here, the silicified modified alunite-based powder usually uses alumite. Particularly, when the silica component contains 50 wt% or more, sufficient strength due to self-hardening can be obtained. Therefore, it is preferable to use this. Further, it is preferable that the silicified modified alumite-based powder has a particle diameter of 15 mm or less. 15 silicified modified alunite
mm or less, the reactivity is improved,
The strength of the ground improvement material itself of the present invention can be increased.
In addition, as a pulverizer for obtaining such a granular material,
A general pulverizer such as a jaw crusher, an impeller breaker, a roller mill, and a cage mill can be used.

As described above, the ground improvement material of the present invention is obtained by mixing the three components of the hard-burned quicklime powder, the calcium sulfate-based hardened powder, and the silicified modified alunite-based powder.
Therefore, firstly, the ground is compacted by the expansion effect of the hard-burned quick lime powder granules due to the digestion and water absorption reactions, and secondly, the three components cause a pozzolanic reaction, and further, ettringite is formed to increase the strength of the material itself. be able to. As described above, the material itself is effective in increasing the strength of the liquefaction resistance and the ground in order to develop the strength by hardening, and the ground improvement material of the present invention having the strength can obtain long-term durability. it can. In addition, by the generation of ettringite, the pH can be suppressed as compared with the conventional quick lime pile construction method or a material to which cement is added or used, and the adverse effect on the surrounding environment can be prevented.

The ground improvement material according to the present invention can be mixed with inorganic materials such as granulated blast furnace slag, coal ash (fly ash), locally generated soil, stone powder, and screenings to these three components. . Granulated blast furnace slag is a mixture of lime, silica, and alumina,
It reacts directly with water and hardens due to the presence of calcium hydroxide and sulfate as alkaline components. Therefore, self-hardening can be further improved by mixing granulated blast furnace slag having such properties. In addition, this granulated blast furnace slag is, for the same reason as above,
It is preferably a fine powder having a particle size of 15 mm or less.

Coal ash is a spherical powder containing a large amount of silica. Thus, the granulated blast furnace slag and the coal ash contribute to the pozzolan reaction and the generation of ettringite since they contain silica and alumina components, and can improve the material strength. In addition, locally generated soil, stone powder,
Screening plays a role as a so-called fine bone material in the expanded and hardened ground improvement material. These inorganic materials can be used alone or in combination of two or more.

The mixing ratio of the three components of the hard-burned calcined lime powder, the calcium sulfate-based hardened powder, and the silicified modified alumite-based powder described above was determined on a weight basis as a result of the test. Quick lime powder 10% to 60%, calcium sulfate hardened powder 3% to 30%, silicified modified alunite powder 6%
６０60%, and the total was preferably 100%. Further, in the case of four components including an inorganic material, the total of the mixing ratio of the four components is 100% on a weight basis, and the mixing ratio of the three components is in the same range as described above, that is, the hard-burnt lime powder. 10% granules
６０60%, and the calcium sulfate-based hardened powder is 3% 〜3
0%, the silicified modified alumite-based powder was determined in the range of 6% to 60%, and the result was that it is preferable to make the shortage the mixing ratio of the inorganic material. Therefore, the mixing ratio of the inorganic material is a value obtained by subtracting the total of the mixing ratios of the three components from 100. It has been confirmed that the desired effect is hardly exhibited when the ratio deviates from this range.

By changing the mixing ratio as described above, the effect can be adjusted depending on the conditions of the soft ground to be treated, and the workability is improved. For example, when it is desired to increase the expansion action, the amount of the hard-burned lime powder should be increased with respect to the total amount of the ground improvement material, and when the strength of the material itself is to be increased, the desired strength is not increased. The amount of silicified modified alumite-based granules, granulated blast furnace slag, etc. may be adjusted so that it can be obtained.

[Soil Improvement Method] An embodiment of a ground improvement method according to the present invention will be described below with reference to FIG. The ground G to be treated is drilled, and the pile 1 is constructed by filling the hole with the ground improvement material to form the cured body 2 expanded in the ground G. Thereby, each component of the ground improvement material is reacted with the moisture in the ground G,
The ground G is improved by causing the above-described action. The method for constructing the ground improvement material in the ground G does not require any special means, and a commonly used method can be used. For example, it is preferable to use a method that does not involve vibration, such as a casing auger method.

The ground improvement material filled in the pile G in the ground G by such a method, for example, the casing auger method has the following two effects. Primarily,
Second, the hard-burned quicklime powder expands due to a hydration reaction, and secondly, the ground improvement material itself hardens due to the pozzolanic reaction and the formation of ettringite, and develops strength. Due to this first effect, the expansion effect, the soil improvement material increases the density of the surrounding ground when processing sand, and consolidates the surrounding ground when processing clay. Promote. Here, the hard-burnt quick-lime powder in the ground improvement material produces a slow-acting expansion effect with a low hydration rate, so that the existing structure is not affected by an increase in earth pressure due to expansion. In addition, the pile 1, which has exhibited strength as the cured product 2 by the second effect, the pozzolanic reaction and the generation of ettringite, has long-term durability. The pile effect of the pile 1 formed in the ground G as described above can also have ground improvement effects such as an increase in strength and a decrease in settlement.

When the pile 1 is constructed in the ground G, it is not necessary to tighten the ground improvement material, so that a method that does not involve vibration, such as a casing auger method, can be used. It is possible to avoid adverse effects such as vibration and noise as much as possible.

[0028]

EXAMPLES Hereinafter, the ground improvement material according to the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. In this example, dihydrate gypsum was used as the calcium sulfate-based hardened powder, alunite was used as the silicified modified alumite-based powder, and coal ash was used as the inorganic material.

Example 1 A ground improving material 1 was prepared by mixing hard-burned quick lime powder, dihydrate gypsum and alunite in the amounts shown in Table 1. Example 2 Ground calcined lime powder, dihydrate gypsum, alunite, and coal ash were mixed in the amounts shown in Table 1, and ground improvement material 2 was used.
It was created.

[0030]

[Table 1]

After a pile is formed with respect to each of the soil improvement materials 1 and 2, the pile is put into a viscous soil having a high water content, and the volume expansion rate at the short term age and the long term age, and the long term The unconfined compressive strength at the material age was measured. The results are shown in FIGS.

As shown in FIG. 2A, the ground improvement material 1
In addition, both the ground improvement material 2 and the ground improvement material 2 are expanded for 10 days, and are of a late effect type. The difference in the volume expansion coefficient between the ground improvement material 1 and the ground improvement material 2 is due to the difference in the amount of the hard-burned lime powder granules.

As shown in FIG. 2B, the ground improvement material 1
The expansion of both the ground improvement material 2 and the ground improvement material 2 has been completed after 10 days. The difference in the volume expansion coefficient between the ground improvement material 1 and the ground improvement material 2 is due to the difference in the amount of the hard-burned lime powder granules.

As shown in FIG. 2C, the ground improvement material 1
The unconfined compressive strength of the soil improvement material 2 and the ground improvement material 2 has been developed with the passage of the material age. The ground improvement material 2 to which coal ash has been added has a higher uniaxial compressive strength than the ground improvement material 1 after a certain period of time.

[0035]

The ground improvement material according to the present invention described above contains hard burned lime powder, calcium sulfate-based hardened powder, and silicified modified alumite-based powder. Shows a slow-acting swelling action and does not adversely affect existing structures or the surrounding environment. In addition, the calcium sulfate-based hardened granule material, and the silicified modified alumite-based granules, the hardened body develops strength, so it is effective for increasing liquefaction resistance and ground strength. . Further, by adding an inorganic material such as granulated blast furnace slag, it is possible to improve the self-hardening property and strength. In addition, by changing the mixing ratio of the components, the action such as expansion can be adjusted depending on the conditions of the target ground, so that the workability is improved. Furthermore, when constructing a pile or the like, it is not necessary to compact the pile by vibration, so that the influence of vibration and noise on existing structures and the surrounding environment can be suppressed.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating an embodiment of a ground improvement method according to the present invention.

FIGS. 2A and 2B are diagrams showing characteristics of a ground improvement material 1 and a ground improvement material 2 of the present embodiment, wherein FIG. 2A shows a volume expansion coefficient at a short-term age, and FIG. And (c) shows the uniaxial compressive strength at a long term age.

[Explanation of symbols]

 1 ... pile 2 ... hardened body G ... ground

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Katsuhiro Nakura 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei Construction Co., Ltd. (72) Kenichi Horikoshi 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei Corporation (72) Inventor Yasushi Fujiwara 1-25-1, Nishishinjuku, Shinjuku-ku, Tokyo Taisei Corporation (72) Inventor Toshiji Kojima 107 Kurihara Nitta, Mizuho-cho, Nishitama-gun, Tokyo Inside the Industrial Co., Ltd. (72) Inventor Hiroki Goto 5-32-7 Sendagaya, Shibuya-ku, Tokyo Shinjuku Bldg. 5F Okutama Industry Co., Ltd. F-term (reference) CA01 EA04 EA05 EA10 EB06

Claims (5)

[Claims] 1. A ground improvement material that expands and hardens to improve the ground by reacting with moisture in the ground, and comprises a hard-burned quicklime powder, a calcium sulfate-based hardened powder, and a silicified powder. Characterized by containing a modified alumite-based powder,
Ground improvement material. 2. The mixing ratio of the hard-burned quick lime powder, the calcium sulfate-based hardened powder, and the silicified modified alunite-based powder is such that the hard-burned quick lime powder is 1 in weight basis.
0% to 60%, the calcium sulfate-based hardened powder is 3%
-30%, the silicified modified alunite-based powder is 6% -60%
Wherein the total is 100%.
The ground improvement material according to claim 1. 3. The ground improvement material according to claim 1, comprising an inorganic material. 4. The total of the mixing ratio of the hard-burned quick lime powder, the calcium sulfate-based hardened powder, the silicified modified alumite-based powder, and the inorganic material is 10 by weight.
0%, and the mixing ratio of the hard-burned quick lime powder, the calcium sulfate-based hardened powder, and the silicified modified alunite-based powder is 10% to 60%.
%, The calcium sulfate-based hardened powder is 3% to 30%,
The ground improvement material according to claim 3, wherein the silicified modified alunite-based powder is determined in a range of 6% to 60%, and a deficiency is a mixing ratio of the inorganic material. 5. A method for improving the ground by forming a cured body expanded in the ground using the ground improvement material according to any one of claim 1 and claim 4, Ground improvement method.