JPH05346018A - Improving material for poor sediment and its improving method - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To easily improve soft excavated soil to the level of general residual soil. [Composition] Fine fibrous material generated from papermaking sludge (hereinafter referred to as PMF) against soil and sand that are soft and easily flowable.
(Referred to as), and improving the slump value to about 10 or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved material for improving the softness of excavated soil showing a softness in the excavated soil generated during construction work and a method for improving the softness.

[0002]

2. Description of the Related Art A large amount of excavated earth and sand is generated when laying pipelines for communication, electricity, water and sewage, or when constructing tunnels by shield work.

[0003] In the soft cohesive soil below the groundwater level, the underwater excavation method, the earth pressure system shield method in which bentonite / clay additives are added, and the mud pressure type shield method in which bentonite mud is used, the water content of excavated soil is In addition to being highly fluid, the soil containing bentonite cannot easily remove water.

If the water content of such earth and sand is high,
Due to the property that it easily flows due to vibration, it is difficult to pile up a large amount and it may be restricted in transportation and handling. Especially when carrying out by a dump truck, due to repeated sudden starts and stops during transportation due to traffic conditions, the loaded sand may fluidize and may spill from the loading platform. Must be: In addition, sludge with high water content such as bentonite muddy water cannot be transported by a dump truck, so it is necessary to use a special vehicle such as a tank truck.

Therefore, as a method for improving such a soft and easily fluidized property, a natural dehydration (drying) method is temporarily set and sun-dried. Mechanical dewatering method The water content of the excavated soil is reduced by mechanically dewatering with a water breaker. Chemical dehydration method The water content is reduced by quicklime, cement-based solidifying agents, polymeric water-absorbing agents, etc. A method of removing water contained in the excavated soil and improving it has been considered.

However, in the case of handling a large amount of soft soil, the natural drying method requires not only a vast site but also a long time. Further, in the mechanical dehydration method, the mechanical equipment becomes large in size, which is economically problematic.

Further, in the improvement method using quick lime or cement-based solidifying agent, since the improved earth and sand exhibits strong alkalinity, there may be a problem in the subsequent handling.

As described above, according to the conventional technique, it is difficult to improve the soft soil having a large water content and easily fluidized, and most of them are handled and treated as industrial waste. When treating as industrial waste, it is necessary to entrust the treatment to a specialist, which not only increases the treatment cost, but also enhances recyclability such as reuse as a backfill material from the viewpoint of environmental conservation. Was wanted.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to improve the above-mentioned drawbacks, and its purpose is to remove soft excavated soil generated at a construction site from paper mills and recycled paper mills. By adding fine fiber material (hereinafter referred to as PMF) generated from the discharged papermaking sludge,
When mixed with soft excavated soil, it imparts appropriate cohesive strength and water stopping ability to the mixed soil, and easily improves the soft excavated residual soil, which has been difficult to improve conventionally, to the level of general residual soil.

That is, even after adding the PMF of the present invention to the soft soil to be improved, the soil quality is not changed to high alkalinity, and after the PMF is mixed, a cement-based solidifying agent is added. As in the case of the above, the soil properties of the soft excavated residual soil are immediately improved without requiring a standing time for the hardening reaction to proceed. This makes it easy to handle and transport large amounts of earth and sand, and is economically superior.In addition, it is an improved material that can make the soft excavated residual soil that was conventionally treated as industrial waste into a water content ratio similar to that of general residual soil. It provides a method.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is to provide an improving material for soft earth and sand containing fine fibrous material produced from papermaking sludge as a main component. Further, the present invention is a method for improving soft soil by improving the soft nature of the earth and sand by mixing fine fiber with slump value of about 10 or less to the earth and sand which is soft and easily flows. Is the gist of the invention.

[0012]

[Function] The addition of this PMF has the effect of absorbing the water contained in the soft soil and entangled with the fine-grained soil contained in the soil, increasing the bond strength of the soil and eliminating the fluidity (connector effect). ..

[0013]

EXAMPLES Next, examples of the present invention will be described. Figure 1
Shows the effect of adding PMF. In FIG. 1, 1 is PMF, 2 is water, 3 is soil particles, and 4 is a clod. (A) "Step 1" When the moisture 2 released by the absorbing action of PMF1 is absorbed and the soil particles 3 are also absorbed by the improving material, the apparent water content ratio becomes low, and the fluidity of soft soil is suppressed. (B) “Step 2” Next, these are 3 to 5 mm due to the entanglement effect of the fibers.
A lump-like material 4 is formed, and the fluidity further disappears. (C) "Step 3" The soft earth and sand having fluidity only comes into contact with air only on its outer surface, but when it grows into an earth mass 4 of about 3 to 5 mm,
By increasing the surface area in contact with the air surface, the adsorbed water evaporates, the drying is accelerated, and the water content ratio can be lowered.

In order to further improve the soft soil,
Since it is necessary to devise a method of mixing the PMF with the improved soft excavation residual soil, the present inventor proposes a method of easily improving the PMF with the following method. The soft soil and sand improving material of the present invention is relatively easy to mix because it is refined into a granular form. Therefore, it is possible to mix the soil with human power at the site where the soft soil is generated, but in order to improve the soft soil that is generated in a large amount, it is necessary to mix and improve it by using a construction mechanism such as a backhoe or a clam cell.

FIG. 2 shows an apparatus for improving soft soil used in the method of the present invention. In the figure, 5 is a hopper, 6 is a regulating valve, 7 is a rotary drum, 8 is a blade plate,
9 is an angle adjusting device, 10 is a drive transmission device, 11 is a drive motor, and 12 is a mount. This soft soil improvement device
Rotating drum 7 for mixing soil and improved material (PMF)
It is composed of a hopper 5 for storing the. Drive motor 1
When 1 is driven, the rotary drum 7 is rotated via the drive transmission device 10. The improving material PMF is provided with a regulating valve 6 so that the mixing amount can be adjusted, and the rotary drum 7 is provided with a blade plate 8 for facilitating the mixing of the soft soil and the improving material PMF. Further, the angle of the rotary drum 7 can be adjusted by the angle adjusting device 9. A method of using this soft soil improving apparatus will be described. While the rotary drum 7 is being rotated, the soft sand is put into the rotary drum 7 and an appropriate amount of the improving material PMF is added to the blade plate 8.
And the improved soil is discharged from the rotary drum 7. When the mixing degree of the soft soil and the improvement material PMF is not good, the rotation speed of the drive motor 11 or the angle of the rotary drum 7 is adjusted, or both of them are adjusted to obtain good soil removal. You can That is, by using this apparatus, the soft soil and the improving material can be easily mixed.

FIG. 3 is an example of an improvement system using a soft soil improvement apparatus. The soft soil discharged from the construction work is temporarily placed in the sediment hopper 13. When the transportation dump truck 16 reaches the construction site, the soft earth and sand is transferred to the soft earth and sand improving device by the earth and sand transfer screw conveyor 14 attached to the earth and sand hopper 13. The soft earth and sand transferred to the soft earth and sand improvement device is improved by the improvement mechanism described above, and the soft earth and sand is discharged onto the belt conveyor 15 and loaded on the transport dump truck 16. By installing this mixing device between the earth and sand hopper and the dump truck for transportation, it is possible to improve the soft earth and sand without greatly changing the conventional work form.

Next, the addition amount of the improving material for soft soil according to the present invention will be described. This addition amount cannot be uniquely determined because it varies depending on the water content of the soft soil. Generally, the degree of moisture contained in sediment is
It is indicated by the water content. This is the weight ratio of the amount of water contained in the earth and sand. The larger the amount of water, the softer the soil becomes, but its softness may vary greatly depending on the particle size distribution. Generally, the larger the particle size of soil, the weaker the water content becomes.

As an index showing this softness, there is a slump value test (JIS A1101). That is, the degree of softness can be shown by performing a slump value test for measuring the consistency showing the softness, which is one of the properties of concrete that is not yet hardened. It is said that the extent to which sedimentation is not self-supporting and does not show fluidity and construction machinery such as a bulltozer does not become muddy during backfilling is about 5 to 10 cm in a slump value test for measuring the consistency of concrete.

This slump value test was conducted with a bottom diameter of 20 cm,
Concrete that does not solidify yet, divided into three layers of cylindrical slump cones with a top diameter of 10 cm and a height of 30 cm (sample)
The slump cone is pulled out, and the degree of falling of the sample is measured.

In the indoor laboratory, the improvement material was increased by 2.5% with respect to the weight of the sample soil for three soft soils (sandy soil) having different water contents, and the slump value was measured. 4 results were obtained. (A) is the particle size distribution of the sample soil, and the test of this particle size distribution was according to JIS A1204. (B) shows the relationship between the amount of PMF added and the slump value.

The fluidity can be lost by adding 5 to 20% of the improving material of the present invention to the weight of soft earth and sand. It is necessary to add a large amount of about 10 to 20% in order to make the soil having a high water content ratio and showing softness into a so-called dry state (slump value of 5 cm or less).

However, as described above, it is not necessary to make the slump value 5 cm or less in order to air-dry with the passage of time, and it is necessary to have a certain degree of fluidity for loading on a dump truck or the like. The target slump value may be about 10 cm, and it can be said that about 5 to 10% may be added although it depends on the water content and particle size distribution of the soft soil.

In other words, it can be said that about 50 to 100 kg of the soft soil-improving material of the present invention should be added to about 1 m ³ of sediment. Further, since the soft soil-improving material of the present invention contains 40 to 60% by weight of an organic substance such as cellulose, when the addition amount is large, it becomes a soil containing a large amount of organic matter. Therefore, except for the purpose of improving to organic soil, it is desirable to use the soft soil improvement agent of the present invention in an amount of about 200 kg per 1 m ³ of soil.

According to the present invention, in the improvement of soft excavation residual soil, simplification of the improvement treatment work and the transportation cost of the excavation residual soil after the improvement treatment can be reduced and the improvement treatment cost can be reduced. Further, after the soft soil is improved, it can be reused for backfilling as in the case of general excavated soil. Further, by effectively utilizing the papermaking sludge and the fly ash which is the combustion ash, which has been conventionally discarded by incineration or the like, there is an effect of improving the recyclability of industrial waste.

Next, examples of use of the soft earth and sand improving material of the present invention will be described. This use example is only an example, and may be changed depending on materials and the like without departing from the spirit of the present invention.
It is possible that improvements can be made. At the tunnel construction site for communication in Sapporo city, the soft soil generated during the shield excavation was used, and PMF, which is the soft soil improvement material of the present invention, was used in a weight ratio of the excavated residual soil to 10 kg of this excavated residual soil. The slump value evaluation after the improvement treatment was carried out by adding 0.5%, 5%, 10%, 15% and 20% and thoroughly stirring for 1 minute.

Excavation soil (soft soil) used in this experiment
FIG. 5 shows the particle size distribution of the above, and FIG. 6 shows the slump value after the improvement. In addition, 10 kg of excavated soil, 500 cc of water, 7
The same experiment was performed by adding 50 cc and 1000 cc and further making the soil exhibit softness. These results are also shown in FIG.

From these results, it was revealed that the excavated soil (slump value 10 cm) showing the generated softness is improved by adding the improvement material in an amount of about 2.5% of the weight of the earth and sand. Further, the water content ratio (27.2
%), It can be said that 7.5% of the weight of earth and sand should be added.

The corn index of the soil thus improved was measured after one day and was found to be about 6 to 8 kg / cm ² . This cone index is an important index when selecting a machine that can be used in embankment work.
According to the obtained cone index, it can be said that the bulldozer and the cariole (towed type) can be used sufficiently. In addition, according to the Ministry of Health and Welfare "appropriate treatment of waste generated from construction work", construction sludge has a corn index of 2
The scale is below or below the uniaxial compressive strength of 0.5 Kg / cm ^{2 so} that it cannot be piled up on a vehicle or people cannot walk on it. From this scale as well, it can be said that the application of the present invention improves the state of being treated as general construction waste soil.

[0029]

As described above, according to the present invention as described above, it is possible to reduce the easiness and economical efficiency of the improvement treatment work of soft soil and the transportation cost after the improvement treatment. The effect can be obtained. In addition, effective use of industrial waste and easy reuse of soft soil, which has been difficult in the past, are facilitated, and excellent effects can be obtained from the viewpoint of environmental protection.

Conventionally, since papermaking sludge generated during the production of household paper such as tissue paper and toilet paper from waste paper contains 60 to 70% of water, it is preliminarily dried by a rotary dryer or the like. It is used for incineration or direct incineration, and the ash content is used for landfill or other purposes. As the soft soil and sand improving material of the present invention, a material obtained by drying the papermaking sludge in a dryer and making it into powder granules is used. Therefore, the cost required for the incineration process can be reduced, which can contribute to energy saving measures.

[Brief description of drawings]

1A, 1B, and 1C are schematic views of the mechanism of an improved material.

FIG. 2 shows a soft soil improvement device.

FIG. 3 shows a soft soil improvement system.

FIG. 4 (a) shows the particle size distribution of the sample soil, and FIG. 4 (b) shows the relationship between the addition amount of the improving agent and the slump value (sandy soil) to the soft soil.

FIG. 5 shows a particle size distribution of earth and sand in a use example.

FIG. 6 shows the relationship between the slump value and the addition amount of the improving material to the soft soil in the use example.

[Explanation of symbols]

 1 PMF 2 Moisture 3 Soil Particles 4 Clods 5 Hopper 6 Adjusting Valve 7 Rotary Drum 8 Blade Plate 9 Angle Adjusting Device 10 Drive Transmission Device 11 Drive Motor 12 Frame 13 Sediment Hopper 14 Screw Conveyor 15 Belt Conveyor 16 Transport Dump Truck

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[Procedure amendment]

[Submission date] June 16, 1993

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Brief explanation of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

1A, 1B, and 1C are schematic views of the mechanism of an improved material.

FIG. 2 shows a soft soil improvement device.

FIG. 3 shows a soft soil improvement system.

FIG. 4 (a) shows the particle size distribution of the sample soil, and FIG. 4 (b) shows the relationship between the addition amount of the improving agent and the slump value (sandy soil) to the soft soil.

FIG. 5 shows a particle size distribution of earth and sand in a use example.

FIG. 6 shows the relationship between the slump value and the addition amount of the improving material to the soft soil in the use example.

[Explanation of Codes] 1 PMF 2 Moisture 3 Soil Particles 4 Clumps 5 Hopper 6 Adjusting Valve 7 Rotary Drum 8 Blade Plate 9 Angle Adjusting Device 10 Drive Transmission Device 11 Drive Motor 12 Mounting Base 13 Sand Sand Hopper 14 Screw Conveyor 15 Belt Conveyor 16 Transport dump truck

[Procedure 3]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuo Toyokawa 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Hiroshi Moriya 5-8, Akihabara, Taito-ku, Tokyo Airec Giken Co., Ltd.

Claims (2)

[Claims] 1. A material for improving soft earth and sand containing fine fibers produced from papermaking sludge as a main component. 2. A method for improving soft soil by improving the soft nature of the soil by mixing fine fibers with the soil exhibiting a soft and easy-to-flow property and adjusting the slump value to about 10 or less. ..