JPH11267696A - Treatment of mud water and wet soil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily solidify mud water and wet soil to have a prescribed strength in a short time by adding a hydraulic material such as quick lime, slaked lime, gypsum into the mud water or the wet soil such as construction surplus soil and after mixing, adding sodium acid silicate and mixing to solidify. SOLUTION: The wasted mud water is bentonite mud water-excavated soil.mixed mud water or dug out soil mud water-excavated soil.mixed mud water or the like and contains a large quantity water to form a slurry. The wet soil (dewatered cake) is one obtained by adding a high molecular flocculating into the wasted mud water an and dewatering by pressure to solid-liquid separate. The mud water or the wet soil is fed to a mixer and for example, a high-early-strength Portlant cement (solidifying agent) is added while stirring and mixed. Next, sodium acid silicate (solidifying assistant) is spraying and stirred and mixed. As a result, uniaxial compression strength is increased for a remarkably short aging time, that is in the early time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating muddy water and bottom mud (eg, dredged sludge), dehydrated cakes thereof, and soil containing water such as construction residual soil.

[0002]

2. Description of the Related Art Conventionally, many techniques have been proposed for treating muddy water and water-containing soil, the main ones being (a) a cement treatment method, (b) a quick lime treatment method,
(C) Cement-quick lime method, (d) Cement-gypsum method,
(E) There are the cement-quick lime-gypsum method and the like, but the above treatment method has the following fatal drawbacks.

(1) The method cannot be applied to muddy water or sludge having a very high water content. (2) The solidification time requires a long period (about 25 to 30 days) and is not economical. (3) The strength of the solidified material is low, so that it is difficult to convey and re-use it.

[0004]

SUMMARY OF THE INVENTION The present invention solves the drawbacks of the prior art, and can easily solidify muddy water or hydrated soil to a predetermined strength in an extremely short time. It can be softened, and can be made into fine particles with a predetermined particle size and strength, and can be reused as a wide-range resource such as backing material for primary lining in muddy water shield method The present invention proposes an optimal solidification method.

[0005]

Means for Solving the Problems The first invention is to add and mix a hydraulic substance such as cement, quicklime, slaked lime, gypsum and the like to water-containing soil such as muddy water, bottom mud (sludge, etc.) and construction residual soil.
A method for treating hydrous soil, characterized by adding and mixing an acidic sodium silicate and solidifying the mixture.

The second invention is directed to muddy water or bottom mud (eg, sludge),
Cement, quicklime, slaked lime, gypsum and other hydraulic materials are added to and mixed with hydrous soil such as construction residual soil, and then acidified sodium silicate is added and mixed, followed by solidification, and then the solidified hydrous soil is granulated. And a method for treating hydrous soil.

In the above invention, the acidic sodium silicate is
It is made by adding an inorganic acid such as sulfuric acid or an organic acid such as acetic acid to sodium silicate and mixing to make it highly acidic.Also, it is collected as artificial sand by adjusting the particle size of the granulated particles and making them finer. You can also.

[0008] Further, soft rock can also be formed by charging the above-mentioned solidified muddy water or water-containing soil into a mold immediately before solidifying and solidifying it as it is or by pressurizing (forming) as necessary.

The hydraulic substance (solidifying agent) used in the present invention is cement, quick lime, slaked lime, gypsum, etc., and sodium acid silicate (sodium) is used as a solidifying aid.

[0010] A concentrated aqueous solution of sodium silicate is called water glass. The molecular formula of this water glass is Na ₂ O ·
represented a nSiO ₂ · XH ₂ O. N and X in the molecular formula are molar ratios. Sodium silicate is generally referred to as sodium silicate in a liquid state, and the upper limit is considered to be 4 because the solubility of sodium silicate becomes very small as n increases. Therefore, the molar ratio n in the case of a liquid is 2 to 4.

The acidic sodium silicate is sodium silicate No. 1,
Sodium silicate No. 2, sodium silicate No. 3 and special sodium silicate (including sodium silicate No. 4, molar ratio = SiO ₂ / Na ₂ O
= 1 to 4) and the like are adjusted to be strongly acidic with, for example, sulfuric acid. This acidic sodium silicate solution can be represented by the following reaction formula. Na ₂ O · nSiO ₂ + H ₂ SO ₄ → Na ₂ SO ₄ + n
SiO ₂ + H ₂ O

[0012]

The present invention is constructed as described above and can easily solidify hydrated soil to a predetermined strength in a very short time, so that it can be ground or soft rock as required. Further, it can be made into fine particles having a predetermined particle size and strength.

Therefore, when landfill is performed using the above-mentioned material, ground having a required strength can be formed.

Further, in the excavation work by the muddy water shield method, the muddy water discharged to the outside can be solidified in a very short time without being dewatered, so that it is extremely easy to handle during transportation and the like.

Further, since the solidification is performed in a very short time (however, it is not an instantaneous setting property) and the required strength is exhibited, it is discharged to the outside as a backing material for the backing method of the segment as the primary lining. Mud water can be used. Furthermore, by making the above-mentioned hydrated soil into granules, it can be made into fine particles having a predetermined particle size and strength.

As described above, since the above-mentioned material can be solidified in a very short time, it can be used in a very wide range, such as grounding, softening, agglomeration, fine-graining, and backing material for primary lining in the muddy water shield method. It can be reused as a resource. Hereinafter, embodiments of the present invention will be described with reference to examples and drawings.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Example 1 (solidification of mud water {bentonite mud water-excavated soil / mixed mud water)) 1) Composition of mud water Alternatively, drilling mud is supplied, and the generated soil is discharged to the outside together with bentonite mud or drilling mud (discharged mud). From this discharged mud,
Sand is often separated and reused. The remaining mud is discarded.

Therefore, the discarded mud is bentonite mud-excavated soil / mixed mud, or excavated mud-excavated soil / mixed mud, etc. Since it contains a large amount of water, it is slurry. In this case, the water content of the mixed mud is about 150 to 2
50%, the mud content is about 40-60%. At present, this muddy water is subjected to solid-liquid separation by dehydration under pressure to form a dehydrated cake (water-containing soil) for easy transportation and disposal as industrial waste.

The mud used in the test of this embodiment is mud which is separated from sand at an actual site and then discarded outside.
Bentonite mud-excavated soil / mixed mud (hereinafter simply referred to as "mud").

The muddy water was subjected to a particle size test. The results of the particle size test are shown in Table 1, and the particle size accumulation curve is shown in FIG. Table 2 and FIGS. 8 to 10 show the engineering classification of soil. In the engineering classification of soil, mud was "F". That is,
According to the classification based on the particle size of the mud, it was "fine-grained soil".

[0021]

[Table 1]

[0022]

[Table 2]

2) Solidification of muddy water 300 g of the above muddy water was put in a mixer with a hook-shaped hook stirring blade (hereinafter referred to as a mixer). p. m, while stirring, for example, early-strength Portland cement (solidifying agent) 60
g was added little by little and mixed until sufficiently uniform. Next, sulfuric acid-acidic sodium silicate was uniformly sprayed on the whole, and stirred and mixed for about 1 minute. The mud after stirring and mixing was in a plastic state. Immediately, plastic mold (diameter 5
(0 mm, height 10 mm) into three layers, and each layer was compacted 25 times with a bar.

FIG. 1 shows the relationship between the acidic sodium silicate (SiO ₂ ) and the unconfined compressive strength (σ) for the curing time (indoor natural curing = air curing, average 20 ° C.), 0.5 hr, 1 hr, 2 hr and 4 hr. It is a graph which shows a relationship. This relationship is
In the 100g of muddy water, C = 2
The relationship was defined as a constant x at 0 g and the amount of acidic sodium silicate (SiO ₂ ) as a variable x (C-SiO ₂ = 20-x. For 100 g of muddy water, 20 g of cement and 20 g of SiO ₂
xg. ).

According to this relationship graph, the curing time is 0.5
In the range from hr to 24 hr, SiO ₂ = 40 (C = 20
In each case, the highest value was obtained. At a curing time of 30 minutes, no early strength Portland cement alone shows any strength, but when SiO ₂ = 40,
As seen in FIG. 1, the uniaxial compressive strength is σ0.5 hr =
0.5 kgf / cm ² .

The compressive strength at which a standard human can walk quietly is said to be about σ = 0.2 kgf / cm ² .
If the muddy water discharged by the muddy water shield method is solidified by this solidification method, for example, a human can walk quietly after 30 minutes, so that the handling for transporting the solidified soil is extremely easy. Also, if this treatment method is applied to dredged sludge of bottom mud such as inland seas, lakes, marshes, rivers, waterways, moats, or digging, solidification can be immediately (approximately 80 minutes later). On the other hand, in the case of only early-strength Portland cement, it takes 4 to 6 hours to develop strength, and the compressive strength σ =
It is about 0.2 kgf / cm ² . However, Si
When O ₂ = 40 is added, the compressive strength σ = 3-3.5K
gf / cm ² and increased by a factor of 15 to 17 times.

In short, it is clear that the addition of acidic sodium silicate (solidifying aid) to the early-strength Portland cement (solidifying agent) significantly increases the uniaxial compressive strength in a very short curing period, that is, early. Was.

Further, in the graph of FIG.
Looking at the relationship between the curing time and the compressive strength in the case of ₂ = 20-40, that is, the change with time, the graph shows a slightly convex parabolic curve, but the curing time directly and largely affects the compressive strength. Was admitted. For example,
The compressive strength after 24 hours (see FIG. 2) was C-SiO ₂ =
In the case of 20-40, σ ₂₄ = 9.8 Kgf / cm ² , and in the case of only early-strength Portland cement, σ ₂₄ = 4.3 K
gf / cm ² . That is, the strength is not more than 1/2.
As can be seen from these relationships, the addition of an appropriate amount of sodium acid silicate not only increases the strength at an early stage, but also increases the uniaxial compressive strength by a factor of two or more, as compared to the case of using only early-strength Portland cement. It was recognized that.

Example 2 (solidification of water-containing soil) 1) Composition of water-containing soil (dewatered cake) As described in the composition of muddy water in 1) above, the dewatered cake is discarded muddy water, that is, discharged muddy water. Is a hydrous soil obtained by adding a polymer flocculant to muddy water that separates sand from sand and discharging it to the outside, that is, bentonite mud-excavated soil / mixed muddy water, and performs pressure-dehydration to perform solid-liquid separation. Therefore, its composition is the same as the composition of the mud. Table 3 shows the properties of the hydrous soil (dehydrated cake). It should be noted that the composition of hydrous soil such as bottom mud and construction residual soil is almost the same.

[0030]

[Table 3]

2) Solidification of water-containing soil (dehydrated cake) The dehydrated cake subjected to pressure dehydration is sufficiently stirred and mixed with a mixer (5).
-10 min). The dehydrated cake became a paste. To 300 g of the hydrated soil, 60 g of early-strength Portland cement was sprayed little by little on the whole and kneaded for about 5 minutes, and then sodium sulfate acid silicate was evenly sprayed and stirred and mixed for about 1 minute. Immediately after stirring and mixing, three layers of the plastic mold were compacted 25 times to produce test specimens. Table 4 and FIG. 3 to FIG.
It shows the relationship between the acid sodium silicate and the uniaxial compressive strength in the cases of hr, 2 hr, 4 hr, 6 hr, 24 hr (1 day) and 168 hr (7 days).

[0032]

[Table 4]

This relationship is based on the relation between the water-containing soil (dehydrated cake) 10
0 g, the early-strength Portland cement C was fixed at 20 g, and the acid sodium silicate (SiO ₂ ) was changed to a variable x (C−
SiO ₂ = 20−x). From these relations, the maximum uniaxial compressive strength of the hydrous soil is longer than that of the muddy water (FIG. 1, the addition amount of SiO ₂ is constant at 30 g). 10
0 g). For example, the 0.5 hr _SiO 2: 50 g, in 1hr _SiO 2: 40g, 2
For hr and 4 hr, SiO ₂ : 30 g, and further for 24 hr
(1 day) and 168 hr (7 days) SiO ₂ : 20
g, etc.

FIG. 5 shows the addition amount of the acidic sodium silicate at which the maximum uniaxial compressive strength was obtained at each curing time. From FIG. 3, FIG. 4 and FIG. 5 and the like, it can be seen that, in a short curing time (0.5 hr to 1.0 hr), 40 to 50 g of acid sodium silicate (based on 100 g of hydrated soil) is 0. A strength of about 5 to 1.0 kgf / cm ² can be expected. It was considered that, after prolonged curing (1 day to 7 days), the strength of 10 to 20 kgf / cm ² can be expected with 20 g of sodium acid silicate.

FIG. 4 shows the relationship between each air curing time and the amount of sodium acid silicate added. This relationship is the addition amount (g) of the sodium acid silicate at which the maximum uniaxial compressive strength is obtained at each curing time. Therefore, if the whole (FIGS. 3 to 5) is comprehensively considered, the curing time (0 0.5 to 1 hr), 40 to 50 g of acidic sodium silicate (based on 100 g of hydrous soil)
In this case, a strength of about 0.5 to 1.0 kgf / cm ² can be expected. In addition, it can be considered that with a long curing time (1 day to 7 days), the strength of 10 to 20 kgf / cm ² can be expected with 20 g of acidic sodium silicate (see FIG. 6).

Example 3 (Granulation method) 1) From muddy water From the graph of FIG. 1, the solidification of muddy water is C-SiO ₂ =
At 20-40, with a curing time of 4 hours, the specimen removed from the plastic mold (φ50 mm, H100 mm) is crushed to an appropriate size (about 5 mm), and the soil particles are rolled by shaking for about 10 minutes. In addition, the angular particles are rounded to become soil particles having an appropriate particle size. This method was referred to as granulation or a granulation method.

When crushing and rolling the soil particles by shaking, an appropriate amount of quicklime (C-SiO ₂ -CaO = 20) is used.
-30-20) It was found that granulation became easier when sprayed. At this time, the granulation was sufficiently possible even with the air curing time of about 2 hours. 2) From wet soil (dehydrated cake)

According to the graph of FIG. 3, the composition that maximizes the unconfined compressive strength is C-SiO _{2 at} an air curing time of 1 hour.
= 20-40, 2-30 hrs for 6 hrs, 6 hrs
In the above, it was 20-20. The composition of the granulation experiment of the dehydrated cake is as follows: C-SiO ₂ = 20-30, and the curing time is 4
hr. In the granulation in this case, extremely good soil particles could be produced. In addition, the same composition (2
In 0-30), when the specimen was crushed and the soil particles were rolled by shaking, an appropriate amount of quick lime was sprayed, and the air-curing time was 2 hours, and good granulated particles could be produced. Blending at this time _was C-SiO 2 -CaO = 20-30-20.

Example 4 (Artificial Sand Method) 1) In case of muddy water The application of the muddy water granulation method is, for example, as described in Example 3, C-SiO ₂ = 20-40, curing time 4hr, or _C-SiO 2 -CaO = 20-30-
20, it was shown that granulated particles can be formed in each of about two hours of the curing time. Thus, artificial sand could be produced by appropriately adjusting the particle size of these soil particles.

2) In the case of hydrated soil (dehydrated cake) The application of the granulation method for hydrated soil is, for example, as in Example 3
-SiO ₂ = 20-30, the gas between the curing time 4hr or _{C-SiO 2 -CaO = 20-30-20,} , in the gas between the curing time 2 hr, indicating that each can very good soil particles. And artificial sand could be immediately made from these soil particles.

Example 5 (Regarding Soft Rock Method) Soft rock means a method in which the solidification treatment method of the present invention is used to fill a mold and solidify, or immediately after the mold is filled, a load is applied to apply pressure. This is a so-called pressure solidification method.

Thus, for example, immediately before solidification, the applied load is 50, 100, 200 and 500 kgf, and the pressurizing pressure of the specimen is 10.2, 20.4, 40.7 and 10 kg.
1.8 kgf / cm ² (Cross-sectional area A = 4.91 cm)
² ). Loading time was 1 minute.

Water was added to the clay to make artificial muddy water. This mud was designated as M mud. Table 5 shows the composition of the clay. The water content was 71.2%.

[0044]

[Table 5]

With respect to the M mud, a solidification test was performed in the same manner as in the solidification of the mud in Example 1. Figures 11 and 12
Is a graph showing the relationship between the air curing time and the uniaxial compressive strength. FIG. 13 shows C-SiO ₂ = 20-20 (g).
/ M muddy water / 100 g) is a graph showing the relationship between the change over time and the uniaxial compressive strength.

Considering FIGS. 11, 12 and 13, etc., C-
Assuming that SiO ₂ = 20-20 (g / M muddy water / 100 g), a load test was performed by a soft rock formation method. FIG. 14 is a graph showing the relationship between the applied load and the uniaxial compressive strength when the applied load is applied for 1 minute after 0.5 hour of curing.
Loading load 0 to 200 kgf (0 to 40.7 kgf / cm
^In the range of ² ), it was recognized that the uniaxial compressive strength increased almost linearly from 15 Kgf / cm ² to 57 Kgf / cm ² and reached 3.8 times that of no loading. At a load of 500 kgf (101.8 kgf / cm ² ), 6
It reaches 6 kgf / cm ² , which is 4.4 times.

Summarizing the above, the softening method for M mud has a considerable effect, although it is only for 24 hours, so that it is necessary to apply the softening method to hydrous soil including mud. Therefore, it was considered that it suggested that it could be used for the production of lightweight aggregate.

[0048]

According to the present invention, as described above, muddy water or water-containing soil can be easily solidified to a predetermined strength in a very short time, and can be formed into ground or soft rock as required.

Further, it can be finely divided into particles having a predetermined particle size and strength, and can be reused as a resource for a wide range of materials such as backing materials in the primary lining in the muddy water shield method. Utilization of unused resources has epoch-making effects.

In the above embodiment, the solidification treatment of bentonite mud-excavated soil / mixed mud as the mud and the solidification treatment of the dewatered cake obtained by pressurized dehydration of the mud as the wet soil are described. Bottom mud such as sludge or hydrous soil such as construction residual soil can be solidified by the same method.

[Brief description of the drawings]

FIG. 1 C-SiO ₂ = 20-x for 100 g of muddy water
It is a graph which shows the relationship between an acidic sodium silicate and the uniaxial compressive strength in the case of setting it as.

FIG. 2 C-SiO ₂ = 20-4 for 100 g of muddy water
It is a graph which shows the relationship between the curing period and the uniaxial compressive strength when it is set to 0 and constant.

FIG. 3 C-SiO ₂ = 20 for 100 g of hydrous soil
It is a graph which shows the relationship between acidic sodium silicate and the uniaxial compressive strength when -x is set.

FIG. 4: C-SiO ₂ = 20 for 100 g of hydrous soil
1-day and 7-day curing period (20 ° C) when -x
It is a graph which shows the relationship between acidic sodium silicate and the uniaxial compressive strength in a day.

FIG. 5 is a graph showing the relationship between the air curing time (Hr) and the amount (g) of sodium acid silicate added to 100 g of hydrous soil.

FIG. 6 is a graph showing the relationship between the curing period and the uniaxial compressive strength when C-SiO ₂ = 20-30 is fixed.

FIG. 7 is a graph showing a particle size accumulation curve in a muddy water particle size test.

FIG. 8 is a plastic diagram in “engineering classification of soil” of muddy water.

FIG. 9 is a diagram illustrating triangular coordinates in “engineering classification of soil” of muddy water.

FIG. 10 is a diagram showing triangular coordinates in “engineering classification of soil” of muddy water.

FIG. 11: C-SiO ₂ = 20-x (g / M muddy water / 10
0g) is a graph showing the relationship between the sodium acid silicate and the uniaxial compressive strength in the case of 0 g).

FIG. 12: C-SiO ₂ = 20-x (g / M muddy water / 10
0g) is a graph showing the relationship between the sodium acid silicate and the uniaxial compressive strength in the case of 0 g).

FIG. 13: C-SiO ₂ = 20-40 (g / M muddy water / 1)
12 is a graph showing the relationship between the air curing time and the uniaxial compressive strength when the pressure is constant at 00 g).

FIG. 14: C-SiO ₂ = 20-20 (g / M muddy water / 1)
10 is a graph showing the relationship between the applied load and the uniaxial compressive strength when the load is set to 00 g).

Claims (5)

[Claims] 1. A method comprising adding and mixing a cement, quicklime, slaked lime, gypsum and other hydraulic materials to water-containing soil such as muddy water, bottom mud, construction surplus soil and the like, and adding and mixing an acid sodium silicate for solidification. For treating muddy water and wet soil. 2. A hydrous substance such as cement, quick lime, slaked lime or gypsum is added to and mixed with water-containing soil such as muddy water, bottom mud, construction surplus soil and the like, and then solidified by adding and mixing acid sodium silicate. A method for treating muddy water or hydrated soil, comprising subjecting the treated muddy water or hydrated soil to a granulation treatment. 3. The method for treating muddy water and water-containing soil according to claim 1, wherein the acidic sodium silicate is adjusted to be acidic by adding and mixing an inorganic acid or an organic acid such as sulfuric acid to sodium silicate. 4. The method for treating muddy water and hydrous soil according to claim 2, wherein the granulated particles are adjusted in particle size, refined and collected as artificial sand. 5. The muddy water and hydrous soil according to claim 1, wherein the hydrous soil to be solidified is loaded into a mold immediately before the solidification, and is softened as it is or when necessary by pressurizing to solidify. Processing method.