JPH0765324B2 - Excavator and sand reformer - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for mechanically and electrically efficiently modifying excavated sediment having a high water content.

[Conventional technology and problems]

As is well known, a large amount of excavated earth and sand with a high water content is discharged by the shield construction method and underground continuous wall construction method that use a slurry or stabilizer. Such excavated soil with high water content is regulated as industrial waste and cannot be used as it is for landfilling. For this reason, various attempts have been made to modify the excavated soil,
The efficiency of the treatment process is being improved.

Conventional methods for modifying excavated soil are roughly classified into mechanical methods such as compression drying, and chemical methods that use solidifying materials. Mechanical methods are advantageous in that they can be reformed without the use of a solidifying material, but on the other hand, there is a limit to reforming, and dehydration cannot be sufficiently achieved only by compression. The chemical method can surely improve the solidification material to some extent, but it has a problem that the cost increases due to the increase of pH and the cost of the solidification material and the amount of sediment treatment.

[Object of the Invention]

The present invention is to solve the above-mentioned problem of excavated sediment modification, and more specifically, it can be easily installed at the site of shield construction, wall construction, etc., and the moisture content of the discharged sediment can be adjusted. ， In terms of cost to the extent that it is not treated as industrial waste,
It is intended to develop an apparatus that can effectively dehydrate and reform while satisfying functionality, continuous operability, and labor saving.

[Structure of Invention]

The object of the present invention to achieve the above-mentioned object is to provide a pallet conveyor device for transporting earth and sand, which comprises pallets connected in an endless belt shape and stretched between wheels.
Each pallet is composed of a water-permeable perforated plate, and at the pallet track position from the sediment loading position to the sediment discharging position, a sediment pressing zone is provided to apply pressure from the top to the sediment inside the pallet, and the pressing plate in this sand pressing zone is the anode. It is characterized in that it is a plate and the bottom of the pallet located in this earth and sand squeezing zone is connected to the cathode, and that the earth and sand squeezing and energization are performed simultaneously in the earth and sand squeezing zone. That is, when excavating the excavated earth and sand with a pallet type conveyor device in which a large number of pallets are connected in an endless belt, electricity is applied while pressing the earth and sand in the pallet during the excavation, thereby dewatering by squeezing and squeezing the cathode by the electroosmosis principle. It is designed to perform a high degree of dewatering that cannot be achieved only by mechanical dewatering due to the effect of collecting water on the water, and the degree of dewatering can also be easily performed by adjusting the amount of electricity depending on the soil. . At that time, the pallet is preferably composed of a perforated plate made of an insulating material, and the bottom surface of the pallet is supported by a conductive material in the earth and sand squeezing zone so that the small holes of the pallet serve as a conductive path. In addition, the pallet conveyor device is configured to have a step drive mechanism that repeats stopping and moving, so that the anode pressing plate in the earth and sand squeezing zone operates to compress and energize the earth and sand in the pallet while the conveyor device stops its movement. Good to do.

Examples of the drawings will be described below.

〔Example〕

FIG. 1 shows the entire apparatus of the embodiment of the present invention. As shown in the figure, a large number of endless pallets 1 are connected and stretched over the wheels 2 and 3. When one or both of the wheels 2 and 3 are used as driving wheels to rotate in the direction of the arrow shown in the figure, the hopper 4 for loading sand is installed at the upstream side position of the upper stage (position near the wheel 2). The excavated earth and sand supplied into the hopper 4 is loaded into the pallet 1 from the charging port 6 while being stirred by the stirring blade 5, and is conveyed in the direction of the other wheel 3. The end point of conveyance is the position where the pallet is turned over by the wheel 3, and the earth and sand fall from inside the pallet due to the turning.

In the pallet type conveyor device configured as described above, according to the present invention, each pallet 1 is composed of a water-permeable perforated plate, and at the pallet track position from the sediment loading position A to the sediment discharging position B A structure is provided in which a earth and sand pressing zone C for applying pressure is provided, a pressing plate (pressing plate) 8 of the earth and sand pressing zone C is used as an anode plate, and the bottom of the pallet located in the earth and sand pressing zone C is conducted to the cathode 9. Is. That is, as shown in FIG.
The pallet 1 has side plates 11a, 11 on both sides of a bottom plate composed of a perforated plate 10.
b is raised (the side plates are not raised in the front and back), and the perforated plate 10 of this pallet 1 is used as a sand pressing zone C
The roll 11 supported in the area of is an energizing roll. on the other hand,
The anode pressing plate 8 is positioned vertically above the zone C where the energizing roll 11 exists. This anode pressing plate 8 is connected to a piston 15 which is reciprocated by a cylinder 14 supported by a reaction force receiving steel material 13.
The sand in the pallet 1 is squeezed by the descending motion of. At that time, a direct current is applied between the energizing roll 11 and the anode pressing plate 8 as a cathode. The movement of the pallet is stopped during the pressing by the anode pressing plate 8 and the energization. This behavior is
For example, a clutch is interposed between the drive motor and the drive wheel of the conveyor, and the clutch is released by the detection signal of the limit switch that detects the pressing downward movement of the piston 15 to stop the movement of the conveyor and the piston 15 When the limit switch detects the ascending movement, the clutch is engaged, whereby the anode pressing plate 8 is squeezed and energized while the conveyer movement of the conveyor is stopped.

By this squeezing energization, water flows downward through each hole of the perforated plate 10 which is the bottom plate of the pallet as shown in FIG. 3, but this water is collected in the water receiving gutter 17 and collected in the dehydration tank 18. . In the illustrated example, the perforated plate 10 is made of an insulating material such as a hard resin, and the perforated plate 10 is supported by a current-carrying material (current-carrying roll) so that the water-containing earth and sand existing in the numerous holes thereof serve as a current-carrying path. However, the bottom plate of the pallet 1 may be composed of a laminated body of a material and a metal mesh, and the metal mesh may be used as a cathode for energization. In this case, it is preferable that the connecting portion between the pallets has an insulating structure.

[Action effect]

According to the experiments conducted by the present inventors, when the sand + silt water content of 25% was pressed, the water content was 17% only by compression. However, under the same compression condition, the voltage was 100v and the current density was 0.3. ~
When a voltage of 0.5 A / dcm ² was applied for 6 to 12 minutes (layer thickness: 100 mm), a dehydrated cake having a water content reduced to 7 to 8% was obtained. Experiments were also performed when the voltage was increased to 200v, but there was no great difference from the case when the voltage was 100v. In addition, the latter had a dehydrating effect more than double when applied without applying pressure and when applied with applying pressure. Further, when the conductive powder (iron powder) was mixed in the earth and sand and compressed, the dehydration effect was further improved.

According to the apparatus of the present invention, the functions of compressing, applying and dewatering sediment are simultaneously achieved in the process of delivering sediment by the pallet conveyor. Since it is easy to adjust the degree of compaction of soil and the degree of application, it is possible to improve the dehydration cake to the intended state according to the properties of the target soil, and to perform mechanical dewatering (addition). It is possible to dehydrate excavated sediment exceeding the pressure dehydration limit. In addition, since the device of the present invention can be installed at a construction site to improve the source of excavated sediment and can perform continuous (batch type) processing, the device of the present invention can be used in the process of transporting excavated sediment. By incorporating them, the work can be rationalized and modified at the same time, and the obtained modified soil can be easily handled and reused.

Recently, a water-absorbent resin is sometimes used as a soil stabilizer, but the water-absorbent resin used for this has the property of expelling water when a direct current is applied. The device of the present invention can be advantageously applied to the above-mentioned soil.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the device of the present invention, FIG. 2 is a perspective view of the pallet portion of FIG. 1, and FIG. 3 is III- of FIG.
FIG. 3 is a schematic sectional view taken along the line III-III. 1 …… Pallet, 2,3 …… Wheel, 4 …… Hopper, 6 ……
Sediment inlet, 8 …… Anode pressing plate, 9 …… Current carrying member, 10 …… Perforated pallet bottom plate, 17 …… Water receiving trough, A …… Serial charging position,
B: Sediment discharge position, C: Sediment pressing zone.

Claims (3)

[Claims] 1. A pallet conveyor device for transporting earth and sand, comprising pallets connected in an endless belt form and stretched between wheels, wherein each pallet is composed of a water-permeable perforated plate and extends from a sand loading position to a sand discharging position. At the pallet track position, the earth and sand squeezing zone that applies pressure from the top to the earth and sand in the pallet is provided, and the pressing plate of this earth and sand squeezing zone is used as an anode plate, and the bottom of the pallet located in this earth and sand squeezing zone is connected to the cathode. An excavated earth and sand reforming device adapted to simultaneously perform earth and sand compression and energization in the earth and sand pressing zone. 2. The excavating earth and sand reforming device according to claim 1, wherein the pallet is formed of a perforated plate made of an insulating material, and the member supporting the pallet in the earth and sand pressing zone constitutes a conductive material for a cathode. 3. A pallet conveyor device has a step drive mechanism that repeats stopping and moving, and while the conveyor device is stopping its movement, the anode pressing plate in the earth and sand pressing zone compresses the earth and sand in the pallet. The excavated soil reforming device according to claim 1 or 2.