JP2000008376A - Underwater placing method for soil or coal ash, or mixture of soil and coal ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form the firm ground in the water of the filled ground using soil or coal ash nondeterminable in the liquid limit and plastic limit by mixing a specified quantity or more of clay in the soil or coal ash. SOLUTION: In the case of soil nondeterminable in the liquid limit and plastic limit by a soil test, clay or clay contained soil is mixed so that the clay content is not less than 10 wt.% of the whole. A solidifying agent is added, and if necessary a void forming agent such as a foaming agent is added. Water is further added to knead the soil which is placed in water by a tremie pipe. The soil is therefore solidified without being separated in water to form the ground of the filled ground. In using coal ash or a mixture of soil and coal ash instead of soil, the clay content is to be not less than 10 wt.% of the whole in the same way. The firm ground can therefore be formed in the water of the filled ground using soil or coal ash nondeterminable in the liquid limit and plastic limit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mainly used for forming a ground having a certain strength by mixing a solidifying material such as cement into soil or the like and pouring it into solidified treated soil in the water of a landfill. The present invention relates to a method of casting soil or coal ash or a mixture of soil and coal ash underwater.

[0002]

2. Description of the Related Art Conventionally, a solidified material such as soil and cement and, if necessary, water are mixed to form a solidified treated soil. Mix solidifying material such as cement, voiding agent such as foaming agent or foaming agent, and water as necessary, and cast it as a lightweight material of lightweight solidified soil using tremy pipes on the backside of seawall, etc. Has been done.

[0003] However, depending on the properties of the soil, there is a problem in that the soil is separated in water, and a solidified or light-weight solidified soil of a predetermined quality cannot be obtained. There was no index to date if it should be placed underwater in response to the problem.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a solidified soil which is not separated in water when a solidified material is mixed with soil and water as required and poured into a landfill. Soil or coal ash, for which a clear index can be obtained as lightweight solidified soil,
Alternatively, a method for placing a mixture of soil and coal ash underwater is provided.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the clay content of soil or coal ash or a mixture of soil and coal ash, for which the liquid limit and the plastic limit are not determined, is about 10% by weight or more of the whole. Add clay and soil containing such amount of clay and solidifying material, add water if necessary, knead it, and pour the soil or coal ash, or a mixture of soil and coal ash, into the water with a tremy tube. The present invention relates to a method of casting underwater, and to a method in which the liquid content limit and the plasticity limit are not determined.
Wt% clay or clay containing clay, a solidifying material and a voiding agent such as a foaming agent or a foaming agent are added. If necessary, water is added and kneaded. It comprises a method of placing soil or coal ash to be cast or a mixture of soil and coal ash underwater.

Further, the present invention performs a liquid limit / plastic limit test of soil on soil or coal ash or a mixture of soil and coal ash which has not been subjected to the liquid limit test and the plastic limit test.
When the liquidity limit and the plasticity limit are not determined, add clay or clay-containing soil and a solidifying material in an amount such that the clay content becomes approximately 10% or more of the total weight, and add water as necessary. Soil or coal ash that is kneaded and cast underwater with a tremy tube, or a mixture of soil and coal ash, and that has not been tested for liquid and plastic limits. The liquid limit and plastic limit tests of soil are performed on ash or a mixture of soil and coal ash, and when the liquid limit and plastic limit are not determined, the clay content becomes approximately 10% or more of the total weight. Amount of clay or clay containing clay, a solidifying material, and a void forming agent such as a foaming agent or a foaming agent, and, if necessary, water and kneading, and soil or coal cast into water with a tremy tube. Underwater casting method of ash or mixture of soil and coal ash Ranaru.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, in an embodiment of the present invention, tests on the liquid limit and the plastic limit of soil or the like to be poured into water in a landfill site using a tremee pipe are generally known. The test was performed based on the established soil test method.

[0008] The liquid limit is the water content at the boundary where the soil transitions from the liquid state to the plastic state. Generally, the water content of a soil containing a large amount of water is the minimum shear strength as a plastic body. The plastic limit is the water content at the boundary where the water content of the soil becomes lower and the material becomes brittle and cracks or the like tend to occur, and it becomes difficult to deform freely.

In order to conduct the above-mentioned liquid limit test, a specified soil sample is carried out by changing the water content of the sample based on a specified dropping device and a specified liquid limit test method such as grooving. For example, when a predetermined groove is not cut even when a test is performed with changing the water content ratio, or when data of a predetermined number of drops is not obtained, NP (not found) is set.

In the plastic limit test, a lump of a kneaded sample is formed into a string while rolling between a palm and a ground glass plate. When the diameter of the string becomes 3 mm, the string is broken. At that time, the soil of the cut part is collected and the water content is calculated.However, if the piece is broken before forming a 3 mm diameter string, the water content of the sample is lower than the plastic limit. Add water, start over.
If this operation is not repeated and the specified string is not obtained, NP
(Not determined).

As a result of performing the above-described liquid limit test and plastic limit test on the soil of this embodiment, both the liquid limit and the plastic limit of the soil were NP (not determined). The particle size distribution of this soil was as shown in the particle size accumulation curve A in FIG. In the particle diameter of FIG. 2, clay is 5 microns or less, silt is 5 microns or more and 75 microns or less, and fine sand is 75 microns or more. According to FIG. 2, this soil is characterized by a very low clay content. Cement 1 m ³ per each as the solidifying material in soil not obtained in the above as liquid limit and plastic limit both 100 kg, 15
When 0 kg and 200 kg were added and kneaded, and the same test was performed as in the case where the mixture was poured into water with a tremy tube, the test pieces were separated and the strength was low.

FIG. 1 shows a test apparatus used for the above test. A sample 1 kneaded with a solidifying material is put into a cylinder 2, a piston 4 which is moved up and down by an electric motor 3 is lowered, and the sample 1 is In the receiving container 5 which is a casting water tank having W, a discharge pipe 6 corresponding to a tremie pipe discharges water into the water W. After being cured for 7 days in the cast state, it was taken out, formed into a test specimen for a uniaxial compression test, and tested.

Therefore, clay-containing bentonite was added to the above-mentioned soil. FIG. 2 shows the particle size accumulation curve at that time. Curve B is 90% soil, 10% bentonite,
Curve C is 85% soil, 15% bentonite, and curve D
Shows the case where bentonite was added to the soil so that each weight% of the soil was 80% and the bentonite was 20%. About half of the bentonite used here is clay and the rest is silt, and the soil to be added is not limited to bentonite, and any clay containing clay can be used. Those containing are preferred.

Subsequently, 10% by weight of bentonite, 15% by weight
And 20% by weight of cement mixed with 1
m ³ per each 100 kg, 150 kg and was 200kg added, if necessary kneaded by adding water, was subjected to similar tests to the case of Da設in water using tremie pipe.
The results were as shown in the following table of the relationship between the unconfined compressive strength of clays having different clay contents and the clay content.

[0015]

The above relationship is based on the assumption that the cement amount is 100 kg / m ³ ,
The chart of FIG. 3 shows that each of 50 kg / m ³ and 200 kg / m ³ shows that even if the amount of cement added is different, the unconfined compressive strength can be obtained at a clay content of approximately 10%. It was confirmed that a difference was seen.

In other words, clay having a particle size distribution for which the liquid limit and the plastic limit cannot be determined by NP contains approximately 10% of the clay.
It has been found that, if it is contained so as to be not less than the weight, it does not separate even if it is kneaded with the solidified material and poured into water with a tremy tube.

In applying the method of the present invention, if it is known in advance that the liquid limit and the plastic limit of the applied soil are not determined, the soil containing clay may be used. Clay or clay-containing soil and a solidifying material are added in such an amount that the amount becomes approximately 10% by weight or more of the whole, and water is added and kneaded as necessary, and then the casting is performed underwater. If it is not clear that the liquid and plastic limits of the soil are not determined, after conducting each test of the liquid and plastic limits of the soil, when the liquid and plastic limits are not determined, Add clay containing clay with the same clay content and add solidifying material.

Further, in the test of the embodiment of the present invention described above, only the test of soil alone was performed, but coal ash generally has the same particle size as silt in many cases, and the same particle size as clay has the same particle size. If the liquid limit and the plastic limit are not determined for coal ash, it will be separated like soil when kneaded with the solidified material and poured into water. is necessary. The same applies to a mixture of soil and coal ash.

Further, the present invention relates to a method for preparing a soil or coal ash or a mixture of soil and coal ash in which the liquid limit and the plastic limit are not determined in the same manner as described above, so that the clay content is 10% by weight or more of the whole. Amount of clay or clay containing clay, a solidifying material, and a void-forming agent such as a foaming agent or a foaming agent are added, and water is added and kneaded as necessary. Doing so is also effective.

The foaming agent in this case is also called a gas generating agent, for example, aluminum, magnesium,
Powders such as zinc can be used, and as the foaming agent, admixtures that are usually used when a large amount of foam is generated in concrete, such as protein, savonin, and a resin-based surfactant, can be used. Can be used.

[0022]

According to the above-described underwater casting method of soil or coal ash or a mixture of soil and coal ash according to the present invention, the soil is solidified with a solidifying material and, if necessary, mixed with water for landfill. It is possible to clearly obtain an index for reliably providing solidified or lightweight solidified soil that does not separate in water when the steel is poured into ground water by a tremy pipe.

Therefore, by applying the underwater casting method of the present invention, the underwater ground in the landfill can be made into a strong ground, and the construction cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a sample test apparatus used in an embodiment of an underwater casting method according to the present invention.

FIG. 2 is a diagram showing a grain size accumulation curve of soil tested by the test apparatus of FIG. 1; It is a figure which shows the change of a uniform particle diameter.

FIG. 3 is a table showing clay content and unconfined compressive strength.

Claims (4)

[Claims] 1. An amount of clay or clay in which soil or coal ash or a mixture of soil and coal ash for which a liquid limit and a plastic limit are not determined is such that the clay content is approximately 10% by weight or more of the whole. A method of pouring soil or coal ash, or a mixture of soil and coal ash, into which soil and a solidifying material are added, and if necessary, water is added and kneaded, and the mixture is poured into water by a tremy tube. 2. A soil or coal ash or a mixture of soil and coal ash, for which no liquid or plastic limit is determined, contains an amount of clay or clay such that the clay content is approximately 10% by weight of the total. Soil or coal ash, or soil and coal ash, which is added to the soil, solidifying material, and a void-forming agent such as a foaming agent or a foaming agent, and if necessary, kneaded by adding water, and poured into water using a tremy tube. Method of placing a mixture with water. 3. A liquid limit / plastic limit test of soil is performed on soil or coal ash or a mixture of soil and coal ash, and when the liquid limit and plastic limit are not determined, the total clay content is reduced. Add clay or clay containing clay in an amount of about 10% or more by weight and a solidifying material, add water if necessary, knead the mixture, and pour the soil or coal ash or soil into the water with a tremy tube. Underwater casting method of mixture of coal and coal ash. 4. A soil or coal ash or a mixture of soil and coal ash is subjected to a liquid limit / plastic limit test of the soil, and when the liquid limit and the plastic limit are not determined, the total clay content is reduced. Add clay or clay containing clay in an amount of at least about 10% by weight, a solidifying material, and a void-forming agent such as a foaming agent or a foaming agent. If necessary, add water and knead the mixture. An underwater casting method for soil or coal ash or a mixture of soil and coal ash to be poured into water.