JPS62267387A - Mud adjustor - Google Patents

Abstract

PURPOSE:A mud adjustor which provides dug earth and sand with water impermeability and plastic fluidity and can improve stability of earth and mountain and sand release properties, containing gypsum and metallic hydroxide (forming metallic hydroxide) as active ingredients. CONSTITUTION:A mud adjustor useful for mud pressure shield method of construction, containing gypsum and a metallic hydroxide (preferable example; hydroxide of aluminum, iron or magnesium) or gypsum and a metallic hydroxide forming compound (preferable example; slaked lime and metallic sulfate) as active ingredients. EFFECT:Having a wide application concentration range of agent and improved handleability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a mud conditioner used in a mud pressure shield method.

[Conventional technology]

As a shield method for soils that are prone to collapse, such as sand and gravel layers, a mud pressure shield method has been proposed in place of the conventional mud water pressure shield method (for example, the
-54435). In the conventional mud water pressure shield construction method, a face or excavation room is filled with muddy water such as bentonite or clay, and excavation is carried out using the water pressure of this muddy water to prevent groundwater from gushing out from the face and collapse of the face. In contrast, the mud pressurized shield method injects a mud conditioner (viscosity imparting agent) into the excavated soil at the face or in the excavation chamber. This creates a highly viscous solid mud with impermeability and plastic fluidity, and this mud is allowed to stagnate so as to fill the face chamber, causing the face to collapse due to the mud shoal generated by the thrust of the shield propulsion jack. Excavating while preventing.

The method is to discharge mud in a fixed amount in a fluidized solid state.

As a mud conditioner in such a mud pressure shield construction method, bentonite slurry made of bentonite, clay, etc., or CMC or other viscosity imparting agent has conventionally been used.

[Problem that the invention seeks to solve]

Among these, bentonite slurry has low fluidity, so it is difficult to mix with the excavation, making it difficult to handle, and the amount used is difficult to control. In areas where the groundwater level is high, the sludge is washed away, resulting in poor water impermeability and soil drainage, and little effect can be expected on sandy or gravelly ground.

Furthermore, although CMC gives viscosity to mud, it is water-soluble and therefore has problems such as lack of water impermeability.

This invention is intended to solve the above-mentioned problems of the conventional products, and it can provide impermeability and plastic fluidity to excavated soil, improve rock stability and soil drainage, and also improve the application concentration of chemicals. The purpose is to provide a mud conditioner that has a wide range of uses and is easy to handle.

[Means for solving problems]

The present invention is a mud conditioner characterized by containing, as an active ingredient, gypsum and a metal hydroxide, or a compound that produces gypsum and a metal hydroxide.

The mud conditioning agent used in the mud pressure shield method is required to provide impermeability and plastic fluidity to the excavation. In other words, this method differs from the conventional mud water pressure shield construction method, which uses fluid mud water.

In the mud pressurization shield method, fluidized solid mud is used for pressurization, so the mud conditioner enters between the particles and fluidizes the entire soil while remaining solid. Despite this, it is necessary to prevent water from permeating. The fluidized state is such that the mud can be discharged smoothly; if the fluidized state becomes too high, it will protrude due to groundwater pressure and impair the soil drainage performance, so a certain degree of hardness is required.

In the present invention, as such a mud conditioner, a composition containing as active ingredients gypsum and a metal hydroxide, or a compound that produces gypsum and a metal hydroxide is used. In other words, since it is sufficient that gypsum and metal hydroxide are present as mud conditioners at the time of use, a composition containing gypsum and metal hydroxide may be used from the beginning, or a composition containing gypsum and metal hydroxide may be used. may be used to produce gypsum and metal hydroxides at the point of use.

Metal hydroxides include aluminum hydroxide, iron hydroxide,
Preferably, those that form a gel-like dehydrating precipitate, such as magnesium hydroxide. Compounds that produce gypsum and metal hydroxides include a combination of slaked lime and metal sulfates.

The amounts of gypsum and metal hydroxide used are approximately 10 to 700 g of gypsum and 5 to 300 g of metal hydroxide per excavated earthwork Q. Gypsum and metal hydroxide can be used alone or in a mixed state by injecting them into the face or excavation chamber and mixing them with the excavated surface.

Commercially available gypsum has a fast hardening rate, so slaked lime and metal sulfates are reacted to form gypsum and metal hydroxide,
It is recommended to use this. In this case, if slaked lime and metal sulfate are injected into the face or excavation chamber and mixed with the excavation surface to precipitate gypsum and metal hydroxide, the generated gypsum and metal hydroxide can be uniformly finely deposited. Can be dispersed.

When using slaked lime and aluminum sulfate, slaked lime slurry (concentration 200 to 700 g)
/+2) was added at 0.05 to 0.5 Q per excavated soil IQ, and then aluminum sulfate (concentration 300 to 750 g/Q as AQ2 (SO4)3) was added at 0.05 Q per excavated soil IQ.
05~IQ injection, mix and react. Here, it is desirable to specify both injection groups so that ρ]1 after mixing both is in the range of 6 to 9.

When a slurry of slaked lime is mixed with excavated soil and a solution of aluminum sulfate is injected into the slurry, the reaction shown in the linear equation occurs, producing aluminum hydroxide and gypsum.

3Ca (011), + AQ, (SO,)x =
2AQ(OH), + 3CaSO4 The aluminum hydroxide produced here is extremely dehydrating, as it is known that, for example, coagulated sedimentation sludge discharged from water treatment plants contains aluminum hydroxide and is highly dehydrating. It has poor water resistance and is highly impermeable. This fills the gaps in the excavated soil, creating a water-impermeable effect. At the same time, aluminum hydroxide has a lubricant effect and also has a plastic flow effect that reduces the frictional resistance between excavated soil particles. Furthermore, the gypsum produced in the above reaction has a low solubility and precipitates as fine particles, and has a lubricant effect, so it has the effect of increasing the plastic fluidity of excavated soil.

The method of injecting slaked lime and aluminum sulfate is not limited to the above method; it is also possible to inject a slurry made by reacting the two in advance, or add aluminum sulfate first and then inject the slurry. A method of injecting slaked lime from the water may be used, and a combination of magnesium sulfate and slaked lime, or a combination of ferrous sulfate and slaked lime is also effective.

When the mud conditioner of the present invention is mixed with excavated soil, impermeability and plastic fluidity are imparted, preventing the permeation of spring water from the face, and smooth drainage of the mud.
Excavation using the shield method can be carried out efficiently.

〔Example〕

Examples of the present invention will be described below. In the examples, %
is weight % unless otherwise stated.

The drawing is a configuration diagram showing a model plant of the shield machine used in the test. In the figure, reference numeral 1 denotes a sample soil container, which is filled with samples ± 2. An excavation chamber 4 is provided on the side of the container so as to surround a rotating cutter head 3 from three sides, and a screw conveyor 5 is provided at the bottom of the container. is provided and connected to the discharged soil receiver 6. There is a pressure gauge 7 on the top of the container 1.
, a water supply pipe 8 and a drain pipe 9 are connected, and the upper part of the sample ±2 is filled with water 10. Ml and M2 are motors.

The drug was tested using the above model plant. The test conditions and test method are as follows.

Test conditions ■) Sample soil: Mountain sand, water content 5.5% 2) Bentonite slurry (comparative example) Bentonite 10%, clay 36%, water 54% 3) Pharmaceutical agent of the present invention, aluminum sulfate (liquid) 8 %(as Al□O
□) Magnesium sulfate/7820 650g/R ferrous sulfate/7820 300g/Q slaked lime
Gypsum and metal hydroxide were produced by adding 400 g/Q and 700 g/fl of the above chemicals as follows.

■Aluminum sulfate - slaked lime Aluminum sulfate (8%) and slaked lime (400 g/Ω) were mixed at a ratio of 1.4:1.0 in 8 liters. The mixing order is to add aluminum sulfate to the sample soil and knead it.

Subsequently, slaked lime was added and kneaded again. If both chemicals were to be reacted in advance, aluminum sulfate was gradually added to the slaked lime suspension to form a reactant, which was then added in a predetermined amount to the sample soil and kneaded. In the case of other drugs, the mixing order and procedure are similar to this.

■Magnesium sulfate - slaked lime Magnesium sulfate 7+1□O (650 g/Q) and slaked lime (700 g/Q) were mixed at a volume ratio of 10:3.

■ Ferrous sulfate - slaked lime Ferrous sulfate 7H20 (300g/Q) and slaked lime (70
0g/Q) were mixed at a volume ratio of 10:3.

4) Operating conditions Rotation speed of cutter head 3: 2.5 rpm Rotation speed of screw conveyor 5: 5 rpa + water pressure
0.5kg/am” Test method Sample soil 10012 is prepared, and the amount of chemical used is 30%.
In the case of v/v% (30Q added per 100Q sample soil),
17.5 Q of the above aluminum sulfate solution was kneaded with the sample soil, and then 12.5 G of the slaked lime suspension was added and kneaded.

In addition, when the chemicals were reacted in advance, the two were mixed at the above ratio, and the reactant was added to the sample soil and kneaded.

The sample ±2 prepared in this way was placed in the sample soil container 1 shown in the drawing.
was filled. The sample soil container 1 was covered, and the water supply pipe 8 above the sample soil 2 was directly connected to a water faucet to fill it with tap water. After confirming that water came out from the air vent valve, it was sealed, and the water pressure was further set to 0.5 kg/Cm2.

After this, cutter head 3 and screw conveyor 5
The sample soil was extruded by rotating it, and the impermeability at that time was observed w4, and at the same time, the amount of soil removed, the slump value of the soil, the moisture content, etc. were measured.

The same procedure was carried out for other drugs and for the comparative bentonite slurry. If the dissolved concentration of the drug changes, change the blending ratio based on the above mixing ratio and always
H was adjusted to be 6 to 8.

The test results are shown in Table 1. In Table 1, all the chemicals were mixed in advance and made into a slurry, but the results were almost the same even when they were added separately.

The criteria in Table 1 are as follows.

impermeable Good: No water comes out at all.

Good: There is a little amount of water.

No impermeability: A large amount of water comes out.

Good soil removal performance: Water pressure of 0.5 kg/car is maintained, and the mixed soil comes out at the same rate as the screw conveyor rotates.

Protrusion: Although the water pressure of 0.5 kg/d is maintained, the mixed earth and sand protrudes regardless of the rotation of the screw conveyor.

Liquidity Good: Mud-like and self-supporting.

Too soft: muddy and not self-supporting.

From the results in Table 1, it can be seen that the samples of Examples have excellent water impermeability, soil drainage properties, and fluidity, and have a wide applicable concentration range.

〔Effect of the invention〕

According to the present invention, since gypsum and metal hydroxide are used as active ingredients, it is possible to impart water impermeability and plastic fluidity to the excavated soil, improve the stability of the ground and soil drainage, and the applicable concentration range. It has the advantage of being wide and easy to handle.

[Brief explanation of drawings]

The drawing is a configuration diagram showing a model plant of the shield machine used in the examples. 1: Sample soil container, 3: Cutter head, 4: Excavation chamber, 5
Niscrew conveyor

Claims (3)

[Claims] (1) A mud conditioner characterized by containing as an active ingredient gypsum and metal hydroxide, or a compound that produces gypsum and metal hydroxide. (2) The mud conditioner according to claim 1, wherein the metal hydroxide is a hydroxide of aluminum, iron, or magnesium. (3) The mud conditioner according to claim 1 or 2, wherein the compound that generates gypsum and metal hydroxide is slaked lime and metal sulfate.