JP2005264679A - Muddy water classifying technique - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To spray and mix coagulant into discharged muddy water during a time when pumped up and discharged to a ground surface to establish the condition that the muddy water, when discharged to the ground surface, is mixed with the coagulant in an approximately homogeneous manner in ground improving technique for a high pressure injection stirring system. <P>SOLUTION: In the ground improving technique, a pouring shaft 1 which injects liquid solidifying agent via a nozzle at high pressure for mixture and stirring while scraping surrounding sediment away, has a coagulant spray nozzle separately provided at a position somewhat upper than the nozzle. The coagulant having a volume corresponding to the amount of the discharged muddy water to be generated with the construction of improving work is sprayed and supplied via the nozzle to a muddy water stream being pumped up along the pouring shaft 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wastewater treatment technique in a so-called high-pressure jet stirring system ground improvement method.

  As a jet system and agitation system ground improvement method using cement milk, for example, it is confirmed that it has penetrated into the construction ground while rotating a driving shaft equipped with a radial stirring blade at the tip, and has reached a predetermined depth After that, air and ultra-high pressure solidified liquid are jetted by crossing from the nozzle provided at the tip of the blade, and after in-situ injection, pulling out is started while performing the injection, and at a predetermined depth Cross-jet type composite stirring method to stop the injection after confirming that

  A rotating shaft equipped with a horizontally opposed jet nozzle at the tip is inserted to a predetermined depth along a guide hole drilled in the construction ground, and is rotated while jetting air and ultra-high pressure slurry and starts to pull up the rotating shaft. The super jet method to stop the injection after confirming that the predetermined depth has been reached,

Or, a soil-cement type that builds a continuous wall in the ground by installing a chain saw type cutter on the construction ground and moving it laterally, excavating the groove, injecting solidified liquid, mixing with the original soil, and stirring. Medium continuous wall construction method is adopted, but in any case, the amount of mud drainage (including mud water, hereinafter referred to as “mud water”) equal to or greater than the amount of solidifying agent etc. injected into the ground during construction. Is lifted and discharged from the periphery of the penetrating shaft to the ground surface.
The mud water is discharged at the time of excavation and ground improvement, and its property is a mixture of soil, water and cement, has a high water content and high fluidity, and corresponds to industrial waste.

Conventionally, the discharged mud water is temporarily stored in a muddy water reservoir installed in the vicinity of the construction machine, transferred from this reservoir to a dump truck using a sand pump or a backhoe, and taken into a dehydration or reuse system, They are transported to a set disposal site or a designated industrial waste disposal site for disposal. The larger and deeper the soil improvement area is, the larger the amount of mud is, and the more waste it takes to dispose of it. Even if it is disposed of, there are inconveniences that the industrial waste disposal site becomes narrow and the disposal cost becomes high and affects the construction cost.
Even if reprocessing is performed, the range of use is limited in terms of time and location because the mud mixed with cement is the target.

In general, it has been attempted to use a part of the non-self-hardening sludge treatment system for the treatment of the above-mentioned sludge soil water. However, since the treatment capacity is lowered during use, there is no example of continuous use.
For self-hardening (including cement) waste mud treatment,
(A) The viscosity is high and the fluidity is lowered and adheres to the pipe, and the pipe is closed over time. (B) Mud accumulates and solidifies in the pipe portion having a low flow velocity.
(C) In a screw decanter, the viscosity of the mud increases with dehydration and adheres to the case and solidifies.
(D) In the filter, clogging and adhesion of the cloth starts with dehydration and solidifies.
This is because it cannot withstand continuous use unless it is solved.

Separately, a treatment method has been proposed to eliminate pollution problems by collecting and reusing activated cement in the discharged sludge water for cost reduction and effective use of resources. Need.
Japanese Patent Laid-Open No. 7-286320 JP 2001-193100 A

If it is impossible to change the volume of the mud water that is pumped up and discharged with the construction (according to experience, the amount of mud water discharged corresponds to the input capacity of the solidified liquid, etc.) If the mud and water can be separated and the substantial volume of mud water can be reduced, the substantial disposal capacity of industrial waste can be reduced, and the man-hours and costs required for mud water treatment can be reduced. is there. In this case, the separated water can be reused.
Therefore, the problem to be solved is to provide means for easily classifying discharged mud water into water and soil (mixed with cement) on the spot.

In the high-pressure jet agitation system ground improvement method, in the process that the mud water in the ground rises and flows out to the ground surface, a flocculant that makes it easy to separate water and soil is sprayed on the mud water and discharged. It is characterized in that the water from the discharged mud is easily classified by mixing almost uniformly.
If the above-mentioned flocculant is applied at least in the middle of the process in which mud water generated by construction is discharged to the ground surface, the turbulent flow and mud water movement (feeding) that occurs in the mud water before it flows to the ground surface. By mixing and mixing, the mud water and flocculant are naturally mixed naturally until the mud water discharged to the surface is stored in the storage tank.
Based on the above homogeneous mixing, the separation of water from mud water is performed naturally and effectively without any deviation.

The mud water and the flocculant are naturally mixed homogeneously by the turbulent flow generated in the mud water and the agitation and mixing that occurs when the mud water is transported (moved) before the mud water is lifted and moved to the surface. Therefore, it is not necessary to provide special means for uniformly stirring and mixing the two.
It is possible to effectively separate the water from the mud water using a simple device, reduce the substantial disposal amount of the mud water, reduce the disposal cost, and thereby reduce the construction cost.
Partial recycling of materials is also possible.
It is easy to implement and there is no risk of excessive equipment costs.

  To disperse (apply) and mix flocculants that make it easier to separate water from mud water, using at least the flow (turbulence) during the movement and discharge of mud water to the surface.

FIG. 1 a is a schematic view of an example of an apparatus for carrying out the method of the present invention, and illustrates a method of installing a driving shaft in a direction perpendicular to the surface (GL) of the improved (soft) ground.
The casting shaft 1 (diameter, about 20 cm) penetrating into the ground is provided with a mechanical stirring blade extending in the diametrical direction so as to face the tip portion as described above, and a cross jet nozzle Or equipped with a horizontally opposed jet nozzle,

While rotating and pulling up the driving shaft 1 built up to a desired depth, an ultra-high pressure, large volume slurry (liquid solidifying agent, ground improving agent) is sprayed to the ground at the required (improved) depth through the nozzle. A large pile of high quality is created in the ground at high speed and efficiency by filling the slurry, mixing and stirring while scraping the surrounding earth and sand.

Part of the soil that has been scraped off becomes mud water containing sprayed slurry, and flows and discharges along the circumferential surface of the placing shaft 1 along the axial direction toward the ground surface. At that time, mud water and water are discharged. If the flocculant spray for facilitating separation is provided by using a nozzle drilled in the peripheral surface of the placing shaft 1 in the middle of the flow of discharged mud water, the flocculant spray can be dispersed. Since the mud water is partially deflected by the rotational friction of the driving shaft 1, the mud water is discharged to the surface LG. The mud and the flocculant are mixed and stirred uniformly.

It is desirable that the nozzle position arranged on the peripheral surface of the placing shaft 1 is not exposed to the air even when the placing shaft 1 is pulled up from the ground during the improvement work. Therefore, it is provided at a position where the flocculant can be supplied to the mud water at a time slightly above the upper slurry spray nozzle position.
However, when the switching valve is connected and the nozzle is exposed to the air, the position is not necessarily fixed if the nozzle is closed.
In short, the time when it can be mixed in mud water is measured, and it is installed at a position where the flocculant can be supplied.
The timing (spreading) of the flocculant is preferably generated when mud water is generated, but generally starts after the mud water starts to be discharged to the surface LG.
Moreover, the spraying of the flocculant is stopped simultaneously with the stop of the injection of the ground improvement agent.

The amount of flocculant sprayed is the amount of mud water that is generally equivalent to the amount of ground improvement agent (liquid solidifying agent, etc.) that is injected (although it is understood that it is a little larger than that). Then, set the amount of addition commensurate with the amount of ground improvement agent and spray continuously.
The discharged mud water up to the surface LG is once transferred to the treatment facility using a suction or pressure pump or backhoe. At this time, the mud water containing the flocculant is further stirred and mixed more uniformly. And make subsequent classification more efficient.

FIG. 2 shows a cross-sectional view of an intermediate treatment facility for mud water containing a flocculant in the present construction method. This intermediate treatment tank is surrounded by a strong impermeable wall 2 and a bottom surface 3 is made of a porous material. The inner surface of the tank provided with the constructed casing is stuck without any gaps using a mesh having a mesh of 1 to 2 mm.
The material of the mesh 4 is desirably a material such as stainless steel, synthetic resin, etc. that is excellent in water permeability, resistant, durable, durable, resistant to washing and use, and hard to adhere to a solidifying agent.
Discharged mud water 5 transferred from a mud water reservoir provided near the placement shaft 1 by using a suction or pressure pump or a backhoe is accommodated inside the intermediate treatment tank provided with the net 4 stretched.

The bottom surface 3 of the treatment tank is provided with water-permeable holes throughout, and the contained mud water 5 containing the flocculant is naturally squeezed out by its own weight and separated through the net 4, and the treatment tank with time. The substantial capacity of the mud water 5 is reduced.
For example, the volume can be reduced by about 30 to 50% in volume ratio.
Here, since the bottom surface 3 fully supports the weight of the stored waste mud soil, it is desirable that the bottom surface 3 has a strong structure and a support member is provided as necessary. The size of the water permeable holes provided on the bottom surface 3 may be as long as the net 4 is not bent by the weight of the stored mud soil water.
Alternatively, a shape like a crosspiece is also possible.
The separated water collects under the bottom surface 3 and is reused as necessary.

In FIG. 2, the bottom surface 3 of the intermediate treatment tank is shown so as to be separated from the ground surface. However, as long as the separated water can be taken out to the outside without any problem, the illustrated restriction is not imposed.
Moreover, although the bottom face 3 of the intermediate treatment tank is provided horizontally, it may be an inclined face.
The stored waste mud soil water is mixed with the agglomerating agent that has been swollen in the middle of the transfer so far, and it is easy to classify the water naturally, but it was provided on the bottom 3 materials to further promote the separation. You may employ | adopt the means which blows in compressed air intermittently to the accommodation mud water bottom via a nozzle.
The separated water is effectively squeezed out along the air passage.

Thus, the mud soil after natural dehydration is completed and reduced in volume is transported from the intermediate treatment tank to the final disposal site. As described above, since the volume ratio is reduced by nearly 30 to 50%, the processing cost is reduced accordingly.
The water separated from the mud soil will be collected and reused for improvement work.
The present construction method is simple in equipment and procedure, can be carried out anywhere at low cost, and is easy to maintain.
As described above, it is possible to reduce the amount of discharged mud water using a simple device and reduce the treatment cost.

  FIG. 1 b is a schematic view of another example of an apparatus for carrying out the method of the present invention, and a placement shaft 1 penetrating into the ground is provided with a mechanical stirring blade extending in a diametric direction so as to face the tip portion. In addition, a cross jet nozzle is provided, or a horizontally opposed jet nozzle is provided, and the placement shaft 1 built up to a desired depth is rotated and pulled up while the ground is placed on the ground at the required (improved) depth via the nozzle. By spraying ultra-high pressure, large-capacity slurry, scraping the surrounding earth and sand, filling the slurry, mixing and stirring, it creates a high-quality large pile in the ground at high speed and high efficiency. As far as the construction method is concerned, there is no difference from that of the first embodiment of the present invention.

In FIG. 1 b, the steel pipe 6 is surrounded by the casting shaft 1 around the casting shaft 1 by selecting an appropriate place around the casting shaft 1 penetrating into the guide hole, and is substantially parallel to the coaxial pipe 1. The flocculant is sprayed toward the placing shaft 1 (muddy water flow) through the nozzle provided.
The distance between the casting shaft 1 and the steel pipe 6, that is, the distance between the shafts, is efficient for the mud water flow that the flocculant sprayed from the nozzle of the steel pipe 6 is lifted and discharged along the circumferential surface of the casting shaft 1 Short enough to mix.

The depth position in the ground of the nozzle provided in the steel pipe 6 is such that it corresponds to the depth of the upper layer of the improved ground layer, and mud water generated in the construction is lifted and discharged to the ground surface along the placement shaft 1 side. In the meantime, it is assumed that there is enough distance and time to allow the dispersed flocculant to agitate and mix with the mud water.
It is effective that the flocculant spray direction is directed to or along the discharge flow of the generated mud water.

At the stage where the position and depth of the improved ground layer have been determined, a required number of steel pipes 6 are inserted in advance surrounding the placement shaft 1, and the flocculant is sprayed as mud water is lifted and discharged by construction. .
The preparation of the flocculant spraying must be completed before the mud water is lifted and discharged along the casting shaft 1 at the corner.
In this embodiment, since the nozzle for spraying the flocculant is fixed in the ground, the flocculant can be effectively sprayed on the discharged mud water flow. Further, the position of the steel pipe 5 (nozzle) can be corrected according to the purpose.

Also in the case of this example, the amount of the flocculant sprayed in the mud is set to an extent commensurate with the amount of the ground improvement agent to be injected and sprayed continuously.
The timing for spraying and stopping the flocculant is the same as that described in Example 1 of the present invention.
Thus, the discharged mud water forms mud water in which the flocculant is homogeneously mixed without any special treatment until it is raised to the ground surface GL and flows out.
Subsequent discharge, treatment steps and effects based on the discharged mud water accumulated around the driving shaft 1 are the same as those described in the first embodiment.

  In this embodiment method, since the ground improvement casting shaft 1 and the steel pipe 6 for dispersing the flocculant are not the same, each time the position of the casting shaft 1 on the ground surface is moved (changed), The penetration position must also be corrected.

In the examples described above, there was no exemplification of the method for treating the discharged mud water in the underground continuous wall construction method, but also in the construction method, the mud water is discharged and treated during construction. There is no substantial difference from Examples 1 and 2 in that the flocculant is sprinkled and agitated in the mud water and drained to facilitate the reduction of the mud water.

This is a high-pressure jet agitation ground improvement method that enables high-speed and high-quality construction even in narrow construction conditions. Of the large amount of discharged mud water that is generated during construction, the ground improvement method itself With a slight modification, it is possible to achieve a substantial reduction in the amount of discharged mud water without going through special and complicated equipment and processes.
The separated water can be reused.
It can be easily implemented at any construction site, has good equipment (man-hours) versus economic effects, and reliably exhibits a predetermined effect.

It is a schematic diagram of the apparatus which implements this invention construction method. (Examples 1 and 2) It is sectional drawing of the intermediate treatment facility of the mud water containing a flocculant in this invention construction method.

Explanation of symbols

1 Driving shaft 1
2 Impervious Wall 3 Bottom 4 Mesh 5 Mud Water 6 Steel Pipe

Claims (2)

In the ground improvement method of the high-pressure jet agitation system, a part of the mud water generated by mixing and agitating both the sand and sand while removing the surrounding earth and sand by jetting an ultra-high pressure and large-capacity liquid solidifying agent along the placement axis A mud moisture class method, characterized in that the liquid flocculant is supplied to the route for lifting and discharging, and the mixture is naturally mixed before the mud water is discharged to the surface. In the ground improvement method of high-pressure jet agitation system, the liquid coagulant is sprinkled into the mud water generated by mixing and agitating while mixing and agitating both the high-pressure and large-capacity liquid solidifying agent while shaving off the surrounding soil. A mud moisture class method characterized by mixing and mixing substantially uniformly until a part of the muddy water is lifted along the driving shaft and discharged to the ground surface.

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