JP2001040984A - Method for processing earth and sand derived from muddy water type shield construction method, and modifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method capable of making effective use of excavated earth and sand produced from a muddy water type shield construction method and a modifier. SOLUTION: In this method for processing earth and sand derived from a muddy water type shield construction method, excavated earth and sand derived from the muddy water type shield construction method is classified into primary processed earth 11 and secondary processed earth 12 having a smaller average grain size than the primary processed earth 11, after which a modifier 13a containing gypsum and the secondary processed earth 12 are admixed to form a mixture (modified secondary processed earth 12a); the modified secondary processed earth 12a and the primary processed earth 11 or modified primary processed earth having the modifier 13a added thereto are admixed to obtain reformed earth and sand 20. The modifier 13a is added to the excavated earth and sand derived from the muddy water shield construction method and contains gypsum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for treating earth and sand generated in a muddy water shield method, and a modifier added to the earth and sand.

[0002]

2. Description of the Related Art The muddy water shield method is used for constructing tunnels and the like underground. The earth and sand (excavated earth and sand) generated in the muddy water shield method is generated in the form of muddy water. In the process of dehydrating the muddy water for the treatment, a primary treated soil and a secondary treated soil having a smaller particle size than the primary treated soil are used. Classified as treated soil. Since the primary treated soil is mostly sandy, it is used directly or after reforming for backfilling. On the other hand, the secondary treated soil is mostly used as fine particles, and thus is not generally used and is disposed of as industrial waste. In addition, for excavated soil, cement, lime, and the like are mixed, and the remaining soil that is transported after being modified may have a problem with strong alkalinity of water oozing from the remaining soil. Is adopted. However, when gypsum is used as a modifying material, there is a problem that the strength of the modified earth and sand decreases with time because the hydrate of gypsum itself is water-soluble.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and a method for effectively utilizing secondary treated soil generated from a muddy water shield method, which has been used in the prior art except for treating it as industrial waste. An object of the present invention is to provide a modifier that suppresses the strong alkalinity of water oozing out of the soil and suppresses a decrease in the strength of the modified soil with time.

[0004]

SUMMARY OF THE INVENTION The present invention provides a method for classifying earth and sand generated in a muddy water shield method into a first treated soil and a second treated soil having a smaller particle size than the first treated soil.
A method of treating a muddy shield construction method in which a modifier containing gypsum and the secondary treated soil are mixed to form a mixture, and the mixture is mixed with the primary treated soil or the primary treated soil in which the modifier is mixed. It is. Another aspect of the present invention is a modifier added to earth and sand generated in a muddy water shield method, comprising 100 parts by weight of gypsum and calcium oxide-containing materials 1-4.
And 0 parts by weight.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram for explaining an example of a method of treating earth and sand generated in a muddy water shield construction method and classifying the soil into a primary treated soil and a secondary treated soil. The muddy water shield construction method is known, and as an example of this construction method, as shown in FIG. 1, a sealed machine in which a chamber is formed by providing a partition behind a rotary cutter 10a driven by a driving motor. A mud pipe 10c for feeding mud water as a drilling liquid to a chamber 10b, and a mud pipe 10d for discharging mud are connected to the shield type machine 10.
The cutting face is stabilized by feeding and pressurizing muddy water corresponding to the underground water pressure to 0b.

The earth and sand (mixture of sand and silt clay) generated by excavating the soil with the cutter 10 a
0b, mixed with the muddy water fed from the mud pipe 10c by the stirrer blades driven by the driving motor, fluid-transported through the mud pipe 10d by the mud pump, and After being sent, it is sieved by a classifying facility such as a vibrating sifter 1 and coarse particles (hereinafter referred to as primary treated soil
), And the primary treated soil 11 is carried out using the belt conveyor 7 or the like. Primary treated soil 11
Contains about 20% by weight of water. Primary treated soil 11
Contains about 50% by weight or more of earth and sand having a particle size (particle size) of about 0.4 mm to 5 mm in the total amount of the solid content (dry soil).

On the other hand, the separated slurry separated in the vibrating screen 1 and the like is supplied to the adjusting tank 2 and separated into muddy water (circulating muddy water) and slurry by the sedimentation separation operation in the adjusting tank 2. The mud for circulation is supplied to the mud tank 3 and a required amount of water or the like is injected, and a required additive (for example, bentonite, a cellulose-based thickener, etc.) is added to the mud for required viscosity, concentration and specific gravity. After being adjusted to
It is supplied to the muddy water shield machine 10 through the mud pipe 10c and reused.

On the other hand, the slurry separated in the adjusting tank 2 is supplied to a slurry tank 4 and supplied from a flocculant tank 5 (for example, a polyanionic water-soluble polymer such as CMC, polycarboxylic acid, etc.). And agglomerated by a filtration device such as a filter press 6 and the like, and this cake-dewatered cake-like fine particle (hereinafter referred to as secondary treated soil 12). ), And the secondary treated soil 12 is carried out using the belt conveyor 9a or the like. This secondary treated soil 12 contains about 50% by weight of water. The soil contained in the secondary treated soil 12 has a smaller average grain size than the soil contained in the primary treated soil 11. The secondary treated soil 12 has a particle size of about 0.4 m in the total amount of the solid content.
m and less than about 50% by weight.

FIG. 2 is a process chart showing an example of a method for treating muddy water shield method earth and sand according to the present invention. As an example of the method of treating the muddy shield construction method of the present invention, as shown in FIG. 1, the first treated soil 11 containing a large amount of sand and the first treated soil 11 containing a large amount of clay are produced by the muddy shield method.
After sieving the secondary treated soil 12 having a smaller average particle size using a sieve or the like, as shown in FIG. Next, the mixture is referred to as a next mixer 15 and uniformly mixed.
The modified secondary treated soil 12a and the primary treated soil 11 are supplied to a mixer (hereinafter, referred to as a tertiary mixer 16) and mixed therewith to obtain a desired soil ( Hereinafter, it is referred to as a modified soil 20).

FIG. 3 is a process chart showing another example of the processing method of the present invention. The processing method is different from the processing method shown in FIG. 2 in that a mixture of a modifier 13a containing gypsum and a secondary treated soil 12 (hereinafter referred to as a modified secondary treated soil 12a) and a gypsum A mixture obtained by mixing the modified modifier 13b and the primary treated soil 11 (hereinafter referred to as a modified primary treated soil 11a).
Are mixed to obtain the modified soil 20.

As the modifiers 13a and 13b, those containing at least gypsum are used. As the modifiers 13a and 13b, fine powder having an average particle diameter in the range of 1 μm to 20 μm is preferable. Gypsum includes anhydrous gypsum, hemihydrate gypsum and gypsum. Among these gypsums, when hemihydrate gypsum or anhydrous gypsum is used, the solidification performance of the modified earth and sand 20 is excellent due to the contribution of the hydraulic property of the gypsum itself. Α-type and β-type gypsum can be used as the hemihydrate gypsum (plaster of Paris). As the gypsum, natural gypsum of natural products or chemical gypsum of artificial products can be used. By-product gypsum is mentioned as chemical gypsum. Further, it is preferable that the gypsum has a specific surface area of 6000 g / cm ² or more by a Blaine air permeation apparatus performed according to JIS R5201 cement physical test method. Further, it is preferable that the modifiers 13a and 13b contain at least one selected from the group consisting of anhydrous gypsum, hemihydrate gypsum and gypsum in a total amount of the modifiers 13a and 13b in an amount of 70% by weight or more. A mixture 12a obtained by previously mixing a modifier 13a containing gypsum and the secondary treated soil 12 is mixed with the primary treated soil 11 as shown in FIG. 2 or the modifier 13b as shown in FIG. Is mixed with the modified primary treated soil 11a, and the modified soil 20 excellent in solidification strength can be obtained with a small amount of the modifiers 13a and 13b used.

Gypsum 100 is used as the modifiers 13a and 13b.
It is preferable that the calcium oxide-containing material is contained in a proportion of 1 part by weight or more and 40 parts by weight or less (1 part by weight to 40 parts by weight) with respect to part by weight. 1 to 4 calcium oxide-containing materials
By containing 0 parts by weight, a water-insoluble hydrate is formed, the decrease in strength of the modified soil over time is suppressed, and the increased pH immediately after the addition of the modifier is short (about one day).
By adjusting the period up to the discharge disposal, the alkaline waste disposal reference value of pH 9.0 or less, which is an index of the pH control value, can be satisfied. When the calcium oxide-containing material exceeds 40 parts by weight,
The increased pH immediately after the addition of the modifier does not decrease for a long time, which is not preferable. In order to reduce the pH to 9.0 or less within a short period of time after the solidification treatment, it is more preferable to include 1 to 30 parts by weight of the calcium oxide-containing material.

When the modifiers 13a and 13b contain a calcium oxide-containing material, the modified earth and sand 20 having a strength maintaining action and being excellent in preventing the solidification strength from lowering is easily obtained. Preferred calcium oxide-containing materials to be used are those that undergo a hydration reaction, examples of which include cements (examples of which are various portland cements, mixed cements, jet cements, special cements such as alumina cements), quicklime, slaked lime, For example, it is formic lime or slag powder. At least one of these calcium oxide-containing materials is used. Further, when the water content of the treated soil is high, powder materials such as fly ash, calcium carbonate, clay powder and the like can be used in combination to lower the water solids ratio and physically increase the solidification strength.

Modifier 13 containing calcium oxide-containing material
Examples of a and 13b are that the α-type hemihydrate gypsum is 0 to 30% by weight of the total amount of 100% by weight of α-type hemihydrate gypsum, β-type hemihydrate gypsum, ultra-high strength cement and calcium carbonate. The β-type hemihydrate gypsum is 50-99% by weight, and the ultra-high strength cement is 0-99%.
10% by weight and calcium carbonate in a ratio of 0 to 30% by weight. As described above, when the hemihydrate gypsum content is high and the cement content is low as the modifiers 13a and 13b, the modified sediment 20 is maintained in a neutral region and has excellent early strength. The ultra-high strength cement has the highest early strength idea among Portland cements. Therefore, the required strength can be achieved with a small amount of addition.

The modifier 13a is per 1 m ³ of the secondary treated soil 12, modifier 13b is per 1 m ³ of primary treated soil 11,
Gypsum is added so that the amount of gypsum is 20 kg to 200 kg. Solid content of secondary treated soil 12 (dry soil)
The amount of addition per solid or the solid content (dry soil) of the primary treated soil 11 depends on the water content of the secondary treated soil 12, the primary treated soil 11, the specific gravity of the excavated soil, and the like. The modifiers 13a and 13b are added so that the amount of gypsum is 10 kg to 150 kg per 1000 kg of the solid content of the treated soil 11.

The ratio of the amount of the primary treated soil to the amount of the secondary treated soil varies depending on the size of the sieves of the vibrating screen 1. Therefore, it cannot be specified unconditionally.
So that the solid content of the primary treated soil 11 is about 0.2 to 5 parts by weight with respect to 1 part by weight of the solid content of
2 and the primary treated soil 11 are mixed to form the modified soil 20. When producing the modified soil 20, the secondary treated soil 12
Alternatively, a cellulose-based polymer (for example, hydroxyethylcellulose), a water-absorbing resin (a polymer having a hydroxyl group, a carboxyl group, a base of a carboxylic acid, etc.)
For example, a starch-acrylic acid-based polymer), an emulsion (an emulsion containing an organic polymer, for example, an ethylene-vinyl acetate copolymer emulsion) and the like may be added.

An example of the secondary mixer 15 for mixing the secondary treated soil 12 and the modifier 13a is a mortar mixer, which is used for mixing the modified secondary treated soil 12 and the primary treated soil 11. Alternatively, the modified secondary treated soil 12a and the modified primary treated soil 1
An example of a tertiary mixer 16 for mixing 1a is an agitator. By these mixers, the secondary treated soil 12
And the modifier 13a are uniformly mixed.

[0018]

EXAMPLES In the following test examples, "parts" means "parts by weight" and "%" means "% by weight". The excavated earth and sand obtained by excavating the soil by the muddy water shield method shown in FIG. 1 is muddy, and the muddy water containing the excavated earth and sand is classified by the vibrating sieve 1.
Primary treated soil 11 was obtained as soil that did not pass through the sieve (the sieve mesh was 20 mesh). In addition, secondary treated soil 12 was obtained as soil that passed through the vibrating sieve 1 and was filtered and dewatered by the filter press 6. The primary treated soil 11 contains sand and has a water content of about 24.3% in the total amount.
The secondary treated soil 12 comprises clay, and in the total amount thereof,
It contained about 54.8% water. The primary treated soil 11 and the secondary treated soil 12 were used in the following test examples.

As shown in Table 1, the method of adding the modifier to the primary treated soil and the secondary treated soil is shown in Table 1 as four patterns of A, B, C and D. I got Then, the strength of the modified sediment was evaluated by obtaining a cone index for each elapsed time. Table 2 shows the measurement results. In the patterns shown in Table 1, as a modifier, a mixture of ordinary porto cement in a ratio of 11 parts with respect to 100 parts of β-hemihydrate gypsum was used, and the total amount of the modifier used was a primary treatment. The total amount of soil and secondary soil was 100 kg per 1 m ³ .

In Table 1, the primary treated soil (70) is
Of the total weight of primary and secondary soils, 70
%. Addition of a modifier (70)
The expression means that 70% of the total amount of the modifier used is added in the process.

As shown in Table 1, the pattern C or D is composed of a secondary treated soil (mixture) to which a modifier is added and mixed,
In the treatment method of the present invention, the primary treated soil or the primary treated soil to which the modifier is added and mixed is mixed to form a mixed soil, and the modifier is further added to the mixed soil, mixed and discharged as modified soil. is there.

[0022]

[Table 1]

[0023]

[Table 2]

The cone index is based on the standards of the Japan Society of Geological Sciences (JSF).
T 716-1990) Determine the penetration resistance when the cone penetrates into the soil with a cone penetrometer, using the value measured by the cone index test method for compacted soil, and divide this by the sectional area of the cone. Is required. It is well known that measurements made in this manner correspond to uniaxial compressive strength values from the test piece.

From Table 2, it can be seen that the C and D patterns (treatment patterns in which a modifier is added to the secondary treated soil and mixed therewith) according to the examples of the present invention are both more than the patterns A and B of the comparative example. , The Cone Index has increased, supporting the effectiveness of the present invention.

The following Test Examples 1 to 18 are examples in which the modified soil was produced by the processing steps shown in FIG. 2 using the secondary treated soil 12 and the primary treated soil 11, and the characteristics thereof were measured. is there. That is, in the following Test Examples 1 to 18, as shown in FIG. 2, the secondary treated soil 12 and various modifiers were mixed at room temperature (2
5 ° C.) to form a mixture. The mixture and the primary treated soil 11 are mixed at room temperature, and a hydration reaction of the modifier is performed to obtain a modified soil. change over time,
This is an example of examining a cone index and the like. In addition, the following Test Examples 1 to
In 18, 1 m ^{3 of the} secondary treated soil (including moisture) 12
On the other hand, the additive amount of the modifier was 100 kg.
In addition, the secondary treated soil (containing moisture) 12 and the primary treated soil (containing moisture) 11 have a ratio of 2 m ³ of the primary treated soil 11 to 1 m ^{3 of the} secondary treated soil 12. Was mixed.

The pH of the modified soil was measured (at 25 ° C.) on a supernatant obtained by shaking a mixture of 10% of modified soil and 90% of water crushed to 10 mm or less for 1 minute.

Test Examples 1 to 7 As shown in FIG. 2, the secondary treated soil 12 and various modifiers were mixed to form a mixture, and this mixture and the primary treated soil 11 were mixed together for reforming. Make sandy soil and adjust the pH of the modified sand
Was examined over time. The results are shown in Table 3 together with the type of the modifier.

The types of the modifiers used in Test Examples 1 to 7 shown in Table 3 mean the following. A100 is a modifier consisting only of gypsum. A90-H10 is 100 parts of plaster,
It is a modifier obtained by mixing with 11 parts of cement.
A80-H20 is a modifier obtained by mixing 100 parts of gypsum and 25 parts of cement. A70-H30
Is a modifier obtained by mixing 100 parts of gypsum and 43 parts of cement. A60-H40 is plaster 10
It is a modifier obtained by mixing 0 parts and 67 parts of cement. A50-H50 is a modifier obtained by mixing 100 parts of gypsum and 100 parts of cement. A0
-H100 is a modifier consisting only of cement.
The gypsum used was β-type hemihydrate gypsum, and the cement was ordinary Portland cement.

[0030]

[Table 3]

From Test Examples 1 to 3 shown in Table 3, the modifier 13a consisting of gypsum alone or the modifier 13a containing cement in a ratio of 11 to 25 parts to 100 parts of gypsum, and the secondary treated soil 12 and a mixture (modified secondary treated soil) 12
It can be seen that by mixing the mixture 12a and the primary treated soil 11, the modified soil 20 having a pH of 7.0 to 8.6 can be obtained. Test Examples 4 to 7 show that when the cement content in the modifier is 43 parts or more, the pH of the modified soil becomes 11.2 or more. The cone index of the modified earth and sand in Test Examples 1 to 3 was 10 kgf / cm ² after 28 days.
It turns out that sufficient strength is obtained.

Test Examples 8 to 14 Modified earth and sand were prepared in the same manner as in Test Examples 1 to 7 except that fine lime was used instead of cement in Test Examples 1 to 7, and the pH of the soil was changed over time. Was examined. The result is
Table 4 shows the types of modifiers. In addition, A in Table 4 means gypsum, L means quicklime, and the types of modifiers in Table 4
"A80-L20" and the like used a modifier obtained by mixing quick lime at a ratio of 25 parts or the like to 100 parts of gypsum, that is, a modifier composed of 80% gypsum and 20% quick lime was used. Means

[0033]

[Table 4]

From Test Examples 8 to 10 shown in Table 4, if the proportion of quicklime was 0 to 25 parts per 100 parts of gypsum and the modifier 13a was used, the pH of 7.0 to 9.0 was obtained. It can be seen that the modified soil 20 is obtained. The cone index of the modified earth and sand in Test Examples 8 to 10 was 10 kgf / cm ² after 28 days.
It turns out that sufficient strength is obtained.

Test Examples 15 to 18 Contains 70% or more of β-type hemihydrate gypsum, and the remainder contains α-type hemihydrate gypsum, ultra-high-strength cement (ultra-high-strength C), calcium carbonate (charcoal), etc. A modified earth and sand 20 was prepared using the above-mentioned type as a modifier 13a, and the time-dependent change of the pH and the like were examined. Table 5 shows the composition of the modifier 13a used, and Table 6 shows the results of measurement of the change in pH over time.

[0036]

[Table 5]

[0037]

[Table 6]

From Test Examples 15 to 18 shown in Tables 5 and 6, β
If 70% or more of gypsum hemihydrate gypsum is used and the remainder is α-type hemihydrate gypsum, ultra-high strength cement, or calcium carbonate as the modifier 13a, the pH becomes 6.8 to
It can be seen that an approximately neutral modified soil 20 of 8.4 is obtained. The cone index of the modified soil in Test Examples 15 to 18 was 1
After 10 days, it exceeds 10 kgf / cm ² , indicating that sufficient strength can be obtained.

[0039]

As described above, the main effects of the muddy water shield method and the modifier of the present invention are as follows. (1) After the sediment generated in the muddy water shield method is branched into a primary treated soil and a secondary treated soil having a smaller particle size than the primary treated soil, the modifying agent containing gypsum and the secondary treated soil are mixed. By mixing this mixture with the primary treated soil, all the soil can be effectively used without treating the secondary treated soil as industrial waste. (2) The earth and sand generated by the muddy water shield method can be modified into neutral or slightly alkaline earth and sand. (3) A decrease in the strength of the modified earth and sand over time can be suppressed. (4) Since the modified soil is neutral or slightly alkaline, it can be effectively used as soil for plant growth.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an example of a method for treating earth and sand generated in a muddy water shield method.

FIG. 2 is a process chart showing an example of a method for treating muddy water shield method earth and sand of the present invention.

FIG. 3 is a process diagram showing another example of the muddy water shielding method for treating earth and sand of the present invention.

[Explanation of symbols]

1..vibration sieve, 2..adjustment tank, 3..mud tank,
4 ・ ・ Slurry tank 、 5 ・ ・ Coagulant tank 、 6 ・ Filter press 、 7 ・ Belt conveyor 、 8 ・ Filter water tank 、 9 ・
・ Belt conveyor, 10 ・ ・ Muddy water shield machine 10a ・
・ Cutter, 10b ・ ・ Chamber, 10c ・ ・ Slut pipe,
10d ··· Sewage pipe, 11 ··· Primary treated soil, 11a · · · Modified primary treated soil (mixture), 12 · · · Secondary treated soil, 12a
..Modified secondary treated soil (mixture), 13a, 13b..Modifier, 14..Primary mixer, 15..Secondary mixer, 16
..Tertiary mixer, 20.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tetsuya Wakiyama 1-8 Kandanishikicho, Chiyoda-ku, Tokyo Sumitomo Osaka Cement Co., Ltd. (72) Inventor Kaname Aoyama 1-8 Kandanishikicho, Chiyoda-ku, Tokyo Sumitomo Osaka Cement Tokyo Branch Co., Ltd. (72) Inventor Shigeki Abe 2-226, Taisei-cho, Omiya-shi, Saitama F-term in Kumagaya Gumi Kita Kanto Branch (Reference) 2D054 AC05 DA12 DA32 4D059 AA09 BG00 BK30 DA04 DA05 DA06 DA66

Claims (4)

[Claims] 1. Classifying earth and sand generated in a muddy water shield method into a first treated soil and a second treated soil having a smaller particle size than the first treated soil, and then modifying the gypsum-containing modifier and the second treated soil. Mixing the soil with the primary treated soil or the primary treated soil in which the modifying agent is mixed, wherein the mixture is mixed with the primary treated soil or the primary treated soil mixed with the modifying agent. 2. A modifier added to earth and sand generated in a muddy water shield method, comprising at least two components of gypsum and a calcium oxide-containing material, wherein the calcium oxide-containing material is added to 100 parts by weight of the gypsum. A modifier containing from 40 parts by weight to 40 parts by weight. 3. The method according to claim 2, wherein the calcium oxide-containing material is quicklime,
The modifier according to claim 2, wherein the modifier is at least one selected from slaked lime and cement. 4. The method for treating muddy shield method soil and sand according to claim 1, wherein the modifier according to claim 2 or 3 is used as the modifier.