JPH0827768A - Strengtening of sand ground - Google Patents

Abstract

PURPOSE:To strengthen a sand ground by effectively using muddy water by injecting sludge and/or muddy water mixed with a thickener, etc., in fine fiber as required in the sand ground. CONSTITUTION:Sludge on a bottom 6 of the sea, etc., is drawn up by a dredger 5 and delivered to a high pressure pump 8 through a pipe 7. The sludge mixed with fine fibers and other components as required by uniformly dispersing them in the sludge through a pipe 10 from a tank 9 with a slurry containing the fine fibers and one or more of a thickener, an interfacial active agent, a coagulant and a water reducing agent as required while the sludge passes the pipe 7 at a stage before it reaches the high pressure pump 8 is injected into a pipe 3. This sludge is injected into a sand ground with pressure from an opening provided on the pipe 3 and permeates. A plural number of the pipes 3 are buried at a plural number of points as required, and injection with pressure is simultaneously or sequentially carried out from the pipes 3 respectively. Consequently, solid components and the fine fibers sequentially permeate the sand around through weak points with water, and they are distributed all over and strengthen the ground.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for strengthening sand ground. More specifically, the present invention relates to a method for effectively utilizing sand sludge excavated or pumped up in dredging work and / or mud discharged during construction to strengthen a sand ground.

[0002]

2. Description of the Related Art Conventionally, a lot of sand has been used for landfill work, and buildings and houses are built on the sand ground formed by the sand. In particular, in recent years, it has been widely practiced to construct high-rise buildings on the land of the coastal area, called the waterfront plan. Most of them consist of sand ground.

By the way, land subsidence frequently occurs in a landfill such as sand ground, and the sand ground is liable to be in a fluidized state due to a so-called liquefaction phenomenon due to an earthquake or water damage. Subsidence and liquefaction of such ground in the sand ground
Since the danger of sand ground has been pointed out from the fact that it causes large damage such as collapse, damage, and slope of houses, buildings, and other structures constructed on it, it has been pointed out that the danger of sand ground has been increased. Various measures have been conventionally proposed. However, strengthening the sand ground requires enormous effort and cost, and especially if structures such as houses and buildings have already been built on the sand ground, prevent damage to those structures. However, since it is necessary to strengthen the sand ground, it is the current situation that no effective strengthening measures can be found. In addition, it is known to press the water into the ground subsided by pumping up groundwater etc. to stop the subsidence of the ground, but even if this method is applied to the sand ground, the water injected into the sand ground is highly water-permeable. It is not possible to prevent the settlement of the sand ground because it is lost from the sand ground early without stopping.

On the other hand, the global warming is progressing more and more in recent years, and due to the melting of ice in the South Pole and North Pole, the water level of seawater has risen from tens of centimeters to 100 centimeters in the last few decades. Reports have also been made. In order to deal with flood damage that tends to occur as seawater level rises, it is necessary to construct levees and revetments such as storm surge dikes with a height higher than ever before on the shores such as coasts. At the same time, there is a strong demand for prevention of ground subsidence and strengthening of the ground on the shore, that is, in the waterfront area.

[0005] In addition, in the waters such as coasts, harbors, rivers, lakes and ponds, sediments, pebbles, sludge,
Organic substances and the like gradually accumulate on the bottom of the water to form a sludge layer,
The depth of those waters becomes shallow, the water level rises,
This creates the risk of water damage, and also hinders ships from sailing and navigation. Therefore, dredging works such as grabs and pumps are widely used to remove sediments and sludge accumulated at the bottom of water bodies such as the sea, rivers, lakes and ponds. The sediments and sludges are used for landfill work. However, there are cases where landfill work cannot always be performed in parallel with dredging work.In such a case, it is difficult to treat and handle sludge and earth and sand that have been dug up or pumped up by a dredging ship. There is a strong demand for use.

Further, in addition to dredging work, a large amount of mud water containing a large amount of clay minerals such as bentonite, kaolin and montmorillonite, and other minerals is discharged in construction work and civil engineering work. If such muddy water is allowed to flow directly into a river or the sea, there is a problem of causing pollution of the river or the sea, and if the muddy water is purified and then discharged into the river or the sea, etc. There is a problem that it takes time and money. Therefore, from these points, handling mud water discharged in construction work and civil engineering work has been difficult for many years, and various treatment methods have been tried.
I couldn't find an effective method.

[0007]

SUMMARY OF THE INVENTION Under the circumstances as described above, the present inventor has continued to find out an effective strengthening method for sand ground.
At the same time, various studies have been conducted to develop effective methods of using sludge and soil that have been dug up and pumped up in dredging work, as well as effective methods of handling mud water discharged during construction and civil engineering. It was As a result, such sludge or muddy water is mixed with fine fibers obtained from waste paper or the like, and if necessary, one or more of a thickener, a surfactant, a coagulant and a water reducing agent is further mixed. When the mixture is pressed into the sand ground, the solid components and fine fibers contained in the sludge and / or the muddy water will preferentially enter with the water in order from weak spots and void spots in the sand ground. By continuing press-fitting, it is finally distributed over the entire sand ground to be reinforced and stays in the sand ground to strengthen the ground and prevent liquefaction and ground subsidence of the sand ground. The idea was that sludge, muddy water, and waste paper, which had been difficult to use, could be utilized as useful resources. Furthermore, when the present inventor further press-fits and further imparts vibration, the fine fibers and, if necessary, one or more of the above-mentioned other components are mixed into the sludge and / or muddy water sand ground. It was also found that the press-fitting can be performed smoothly, and the present invention was completed based on these findings.

Therefore, the present invention is a method for strengthening a sand ground, characterized in that sludge and / or muddy water mixed with fine fibers are pressed into the sand ground. Further, the present invention, in the sand ground, together with the fine fibers, a thickener, a surfactant,
A method for strengthening a sand ground, comprising press-fitting sludge and / or mud mixed with one or more of a flocculant and a water reducing agent. Then, in the present invention, fine fibers and, if necessary, sludge and / or muddy water in which one or more of a thickener, a surfactant, a coagulant and a water reducing agent are mixed are pressed into the sand ground. At the same time, at the same time as the press-fitting work or alternately with the press-fitting work, further vibration is applied to the sand ground.

In the above, the sand ground formed by the landfill construction was mainly described, but the sand ground targeted by the strengthening method of the present invention is not limited to the sand ground by the landfill construction, and the landfill construction is performed using sand. It may be a sand ground formed by the above method or a sand ground formed naturally by depositing sand or the like without depending on the landfill work. The sand ground referred to in the present invention includes not only the ground formed only of sand but also the ground mainly composed of sand and containing other components such as minerals and soil. Further, as the sand ground in the present invention, any of the ground at least partially consisting of a layer of sand, which is at risk of causing ground subsidence or liquefaction, is the target, for example, the ground whose top layer is a sand layer, The upper layer consists of layers other than sand, and the ground with a sand layer beneath it is the target.

Further, the sand ground to which the present invention is applied is a sand ground on which structures such as houses, buildings, other structures, banks and other civil engineering structures have already been constructed; sand ground. Sand structure in which the basic structure of the building, basement, underpass, water supply, gas, electricity, telecommunication pipes, subway and sewer tunnels, etc. are already installed in the ground (underground); Includes any sandy ground in a vacant land where no etc. are provided.

In the present invention, either the sludge or the muddy water may be pressed into the sand ground alone, or both may be mixed or sequentially pressed into the sand ground. In that case, use sludge and muddy water that are discharged in large amounts during dredging work, construction work, civil engineering work, etc. that have been difficult to handle in the past. It is highly desirable from the viewpoint of effective use. However, the present invention is not limited thereto, and any of sludge and / or muddy water discharged except for dredging work, construction work, and civil works can be used in the method for strengthening sand ground according to the present invention.

When the particle size of the solid component contained in the sludge and / or the muddy water is almost the same as or smaller than that of the particles such as sand forming the sand ground, the solid component contained in the sludge or the muddy water. It is desirable that it can be pressed deep into the sand ground together with water. In this respect, mud water discharged during construction and civil engineering works contains a large amount of clay minerals such as bentonite, kaolin, and montmorillonite, which have a particle size smaller than that of sand, and other minerals. Since it is pressed into and penetrates deep inside, it works effectively to strengthen the sand ground. However, the particle size of the solid component contained in the sludge and / or the muddy water is not particularly limited, and the sludge and / or the muddy water discharged in the above-mentioned dredging work, construction work, civil engineering work, etc. can be used as it is. .

Further, in the present invention, it is necessary to mix the fine fibers in the sludge and / or the muddy water which is press-fitted into the sand ground. Sludge and / or containing fine fibers
Alternatively, by pressing mud into the sand ground, fine fibers permeate deep into the sand ground together with sludge and mud, forming a so-called mesh structure there to reinforce the sand ground and favor sedimentation and liquefaction of the sand ground. Can be prevented. As the fine fibers in this case, pulp fibers, cotton, natural fibers such as hemp; and polyester fibers, nylon fibers, vinylon, viscose fibers, synthetic fibers such as polyolefin fibers or semi-synthetic fibers can be used. Natural fibers such as pulp fibers, cotton and hemp are preferred.

Particularly, as the fine fibers, if pulp fibers contained in waste liquid discharged in the paper industry, pulp fibers contained in used paper such as used newspapers, used magazines, used office paper, etc. are used, It is more preferable that effective use of fibers and waste paper in pulp waste liquid, which has been difficult to handle in the past, can be achieved at the same time. When using fine paper obtained from used paper as fine fibers, cut the used paper into small pieces, and then add an appropriate amount of water, sludge, mud water, etc., and mix them while adding a shearing action. It is advisable to refine the pulp fibers to form a paste-like material or fluid material containing the fine pulp fibers, and mix this with sludge and / or muddy water to be pressed into the sand ground.

The size of the fine fibers mixed in the sludge and / or the muddy water is such that the fine fibers together with the sludge and / or the muddy water can be pressed into the deep depth of the sand ground and penetrate. It is preferable that the size is about the same as or smaller than that of the particles such as sand to be formed, or slightly larger than the particles such as sand. Specifically, the fiber length of the fine fibers is preferably about 2 mm or less. ,
More preferably, it is about 1 mm or less.

The amount of fine fibers mixed into the sludge and / or the muddy water depends on the solid content concentration in the sludge and / or the muddy water, the type and content of the components contained in the sludge and / or the muddy water, the sludge and / or the muddy water. It can be appropriately adjusted according to the condition and content of the sand ground to be press-fitted, and is not particularly limited. The fine fibers can be mixed within a range in which the viscosity of the sludge and / or the muddy water after the fine fibers are mixed is kept within a range such that they can be pressed into the sand ground. Although not limited thereto, the amount of fine fibers to be mixed may be generally about 0.01 wt% to about 50 wt% based on the weight of sludge and / or muddy water.

Further, in the present invention, one or more of a thickener, a surfactant, a coagulant and a water reducing agent are mixed with sludge and / or mud together with the above-mentioned fine fibers, if necessary. can do. In this case, examples of the thickener include carboxymethyl cellulose (CMC), gums such as guar gum, tragacanth gum, gum arabic, and gamte gum. When the thickener is used, the viscosity of the sludge and / or the mud water is increased, so that the fine fibers are uniformly dispersed in the sludge and / or the mud water without settling with the sludge and / or the mud water.
Or settling of solid components contained in mud water is also prevented,
The fine fibers and the solid components contained in the sludge and / or the muddy water can be pressed and penetrated into the depth of the sand ground together with water, and the reinforcement of the sand ground can be further promoted.

As the surfactant, any of conventionally known nonionic surfactants, cationic surfactants, and anionic surfactants can be used. By using the surfactant, The fine fibers and the solid components contained in the sludge and / or the muddy water are uniformly dispersed in the sludge and / or the muddy water without settling, and the fine fibers and the solid components are mixed with the water to the depth of the sand ground. It can be pressed in and penetrated, and it is also effective by strengthening the sand ground.

As the coagulant, any of the organic coagulant and / or the inorganic coagulant generally used in wastewater treatment can be used. The pressed fine fibers and the solid components in the sludge and / or the muddy water can be aggregated at the place where they are pressed and stably held in the sand ground. As the water reducing agent, tannin, lignin, etc. can be used. When the water reducing agent is used, the water content in the sludge and / or mud that is pressed into the sand ground is reduced, and / Or muddy water can be used.

Thickeners for sludge and / or mud,
The mixing amount of the surfactant, the coagulant and / or the water reducing agent is not particularly limited, and the mixing amount of the fine fiber, the concentration of the solid component in the sludge and / or the muddy water, and the sand ground where the sludge and / or the muddy water are to be pressed It can be adjusted appropriately according to the condition and content.

Of the fine fibers and, if necessary, thickeners, surfactants, coagulants and water-reducing agents (these components other than the fine fibers may be collectively referred to as "other components described above") A method of press-fitting sludge and / or mud mixed with one kind or two or more kinds into sand ground, a press-fitting device therefor are not particularly limited, and fine fibers and, if necessary, thickener, surfactant, coagulant Also, any method and device can be adopted as long as they can smoothly press the sludge and / or mud mixed with one or more of the water reducing agents into the sand ground. For example, but not limited to, a sludge in which a pipe is inserted into a sand ground to a predetermined depth and fine fibers and, if necessary, one or more of the above-mentioned other components are mixed. And / or muddy water is introduced using a high-pressure pump or the like, and the sludge and / or muddy water in which fine fibers and one or more of the above-mentioned other components are mixed are discharged from the tip or midway of the pipe into the sand ground. The outer tube with holes or openings that allow sludge and / or muddy water to pass through is inserted into the sand ground, and a small gap is formed inside the outer tube with the inner wall of the outer tube. In this way, an inner tube having a smaller diameter than that is inserted, and fine fibers and, if necessary, one or more of the above-mentioned other components are mixed to produce sludge and / or muddy water such as a high-pressure pump. Introduced using , The sludge and / or muddy water in which fine fibers and one or more of the above-mentioned other components are mixed from the tip of the inner pipe or in the middle thereof are once discharged into the gap between the inner pipe and the outer pipe, and then the outer pipe It can be done by press-fitting into the sand ground through the holes and openings.

The fine fibers and, if necessary, one or more of the above-mentioned other components are mixed to press the sludge and / or the muddy water into the sand ground. Depending on the state of buildings and other structures installed in the ground, you can go vertically, horizontally, diagonally, or some of them in combination. Good. Further, fine fibers and, if necessary, press-fitting of sludge and / or muddy water in which one or more of the above-mentioned other components are mixed may be carried out only from one place, or may be carried out from a plurality of places,
When press-fitting from a plurality of locations, they may be press-fitted one by one or at the same time from a plurality of locations.

Further, sludge and / or muddy water in which fine fibers and, if necessary, one or more of the above-mentioned other components are mixed, are pressed into the sand ground in a predetermined area.
When it is desired to infiltrate, the area is surrounded in the sand ground to form a wall using a suitable material in advance, and the area is surrounded by the fine fibers in the area and the above-mentioned other components as necessary. It is advisable to press the sludge and / or mud mixed with one or more of the above and press it into the area. In particular, a building on or in the sand ground where the sludge and / or muddy water in which one or more kinds of the above-mentioned other components are mixed are injected into the sand, in order to press-fit the fine fibers.
If underground structures are present, it is necessary to select a press-fitting location that does not damage them and perform press-fitting work.

In addition, when years have passed since the sand ground was formed, when a heavy structure is provided on the sand ground, the place where the sludge and / or muddy water is to be injected is the sand ground. When it is deep, the sand ground has already hardened or is under high pressure,
The voids between the sand particles in the sand ground are reduced, and it is difficult to inject sludge and / or muddy water in which fine fibers and, if necessary, one or two of the above-mentioned other components are mixed. There is a case. In that case, if vibration is applied simultaneously with the press-fitting operation of sludge and / or muddy water in which one or two kinds of the above-mentioned other components are mixed, or alternately with the press-fitting operation, the fine fibers are added. And, if necessary, one or two of the above-mentioned other components.
It is desirable because the sludge and / or mud mixed with the seeds can be smoothly injected into the sand ground. When pressurizing the sludge and / or muddy water into the sand by applying vibration, even if the sludge and / or muddy water to be press-fitted are subjected to the press-fitting operation while applying vibration, the sludge and / or muddy water Even if vibration is applied to the part of the sand ground that has already been press-fitted, even if the sludge and / or mud is pressed into the part of the sand ground to be press-fitted while vibrating, or Press-fitting may be performed by using two or more vibration applying methods in combination.

In this case, vibration may be imparted by using fine fibers and, if necessary, one or two of the above-mentioned other components.
Any method may be used so long as sludge and / or muddy water mixed with seeds can be smoothly pressed into the sand ground. Specific examples include a method using a sound wave, a method using compressed air, and a method using them in combination. be able to. In the case of using sound waves, both high-frequency sound waves and low-frequency sound waves can be employed, but it is preferable to use ultrasonic waves because good vibration can be given. Further, in the case of using compressed air, preferable vibration can be imparted by supplying high-pressure compressed air intermittently in a short cycle. In the case of using compressed air, it is desirable to provide in the sand ground an air passage opened to the ground for allowing the compressed air supplied into the sand ground to escape.

When vibration is applied by pressurizing sludge and / or muddy water in which fine fibers and, if necessary, one or two of the above-mentioned other components are mixed, vibration is applied between the sand particles in the sand ground. Void formation is promoted, and further, formation of voids between the sludge and / or muddy water, fine fibers, and other components which are to be or have been press-fitted into the sand ground, close packing are promoted, and press-fitting is promoted. It is presumed that it will be carried out smoothly.

By performing the above-described press-fitting operation, one or more of the solid components contained in the sludge and / or the muddy water, the fine fibers and, if necessary, the above-mentioned other components are water. With this, the weak and vacant places in the sand ground are preferentially invaded in order, and the solid components, fine fibers, and other components are finally distributed throughout the sand ground by continuing the press fitting for a predetermined period. As a result, the solid content of sludge and / or muddy water is filled into the sand ground, and the reinforcing effect by forming a mesh of fine fibers strengthens the sand ground, preventing ground subsidence and liquefaction. . In that case, the water contained in the sludge and / or the muddy water may be partially or wholly stopped in the sand ground together with the fine fibers and solid components depending on the state of the sand ground after the press-fitting. May gradually be lost from the sand ground as groundwater, etc., but in any case, a strengthened sand ground is formed compared with the sand ground mixed with fine fibers and / or mud water before being injected. To be done.

In addition, after sludge and / or muddy water in which fine fibers and, if necessary, one or more of the above-mentioned other components are mixed are pressed into the sand ground, sand is used for the purpose of preventing moisture and other purposes. If you want to remove water from the ground, before, during or after the press-fitting work, install a drainage means such as a paper drain or drain pipe in the sand ground so that one end is exposed to the outside of the sand ground, You may make it drain water positively.

Hereinafter, the present invention will be specifically described with reference to the drawings for understanding the content of the present invention, but the present invention is not limited thereto. FIG. 1 and FIG. 2 are diagrams respectively showing an example of a case in which sludge is press-fitted into a sand ground 1 formed by performing landfill construction on the shore of a sea or a river to strengthen the sand ground, as seen from the vertical direction and from above. Since a high-rise building 2 such as a building has already been constructed on the sand ground 1, a pipe 3 for selecting a position that does not obstruct the high-rise building 2 and pressurizing sludge vertically into the sand ground 1 To bury. The lower part of the tube 3 is formed with an opening 4 through which sludge can pass.

The dredger 5 such as a grab boat or a pump boat excavates or pumps up sludge on the bottom 6 of the sea or river,
This is sent to the high pressure pump 8 through the pipe 7. In the sludge passing through the pipe 7, before the high pressure pump 8, fine fibers and, if necessary, one or more of a thickener, a surfactant, a coagulant and a water reducing agent are added. Pipe 1 from tank 9 containing the contained slurry
0 to supply fine fibers and, if necessary, one or more slurries of the above-mentioned other components and, if necessary, use a suitable mixing device (not shown) to obtain fine fibers and Accordingly, the above-mentioned other components are evenly dispersed in the sludge, and fine fibers and, if necessary, one or more of the above-mentioned other components are mixed and slid into the pipe 3 by the high-pressure pump 8. To do. The fine fibers pressed into the pipe 3 and, if necessary, one or more of the above-mentioned other components are mixed, and the sludge is pressed into the sand ground through the opening 4 provided in the pipe 3 and permeates. .

In the above case, the press-fitting work may be carried out with the pipe 3 left stationary, or the press-fitting may be carried out while the pipe 3 is gradually pulled up as the press-fitting progresses. After the press-fitting work is completed, the pipe 3 may be pulled out from the sand ground 1 or may be buried in the sand ground 1 as it is depending on the situation. The material and dimensions of the tube 3 are not particularly limited,
It has sufficient strength to withstand burying and press-fitting in the sand ground 1 and facilitates press-fitting of fine fibers and sludge containing one or more of the above-mentioned other components as necessary. The pipe 3 can be made of, for example, steel or other metal, concrete, reinforced plastic, or the like.

The pressure at the time of press-fitting the fine fibers and the sludge in which one or more of the above-mentioned other components are mixed, if necessary, is appropriately selected according to the condition of the sand ground and the condition of the sludge. Also, the press-fitting time may be appropriately determined according to each situation. Press-fitting may be performed from only one place, but if it is difficult to strengthen the entire sand ground 1 on which the high-rise building 2 is constructed by only one place, as shown in FIG. It is advisable to embed the pipes 3 in the pipes and press-fit from the respective pipes 3 simultaneously or sequentially. Although FIG. 1 and FIG. 2 illustrate the case where a sludge containing fine fibers and, if necessary, one or more of the above-mentioned other components is mixed only from a place near the sea or river in the sand ground, However, the present invention is not limited to this, and even if the sludge and / or muddy water mixed with fine fibers is injected into the high-rise building 2 by surrounding the high-rise building 2 at several places (4 sides), You may make it from several places of 2 sides or 3 sides of the thing 2.

Further, when it is desired to press the sludge and / or muddy water in which the fine fibers and, if necessary, one or more of the above-mentioned other components are mixed into only a limited area of the sand ground 1, As shown in the plan view of FIG. 3, a suitable blocking wall 11 is embedded in the sand ground in advance, and the fine fibers pressed into the sand ground 1 and, if necessary, one or two of the above-mentioned other components. It is preferable that sludge and / or muddy water containing at least seeds be stopped at the barrier wall 11 in the sand ground 1 so that the sludge and the muddy water are pressed and permeated only into a portion surrounded by the barrier wall 11.

Further, depending on the topography and condition of the sand ground 1, as shown in FIG. 4, the pipe 3 is inserted and buried in the sand ground 1 from the horizontal direction, and fine fibers and, if necessary, from the horizontal direction. Even if the sludge and / or mud mixed with one or more of the above-mentioned other components is pressed in, the pipe 3 is inserted obliquely into the sand ground though not shown.
The buried press-fitting work may be performed.

As an example of the structure of the pipe 3 used for press-fitting sludge and / or muddy water in which fine fibers and, if necessary, one or more of the above-mentioned other components are mixed, FIG.
A single tube having an opening 4 as shown in FIG. 5A, a single tube having no opening 4 as shown in FIG. 5B, and an outer tube 3a having an opening 4 as shown in FIG. 5C. It can be formed from a double pipe or the like which is composed of an inner pipe 3b having no opening 4.

Further, although not shown in FIGS. 1 to 5,
It has been mentioned above that vibration can be applied simultaneously or alternately with the press-fitting operation to accelerate the press-fitting of the fine fibers and, if necessary, the sludge and / or the muddy water in which one or more of the above-mentioned other components are mixed. In that case, depending on the difficulty of press-fitting the sludge and / or muddy water, the vibration may be appropriately applied consistently from the beginning to the end of the press-fitting work, but only during the press-fitting work. It may be done at the end of the press-fitting work.

[0037]

According to the method of the present invention, the sand ground is strengthened by effectively utilizing the sludge excavated or pumped up in the dredging work and / or the muddy water discharged in the construction work or the civil works. Therefore, it is possible to prevent or reduce the settlement and liquefaction of the sand ground, which has been a problem in the past, and to effectively use sludge and / or muddy water which has been difficult to handle. it can.

Further, in the present invention, since the fine fibers are mixed in the sludge and / or the muddy water which is press-fitted into the sand ground, the fine fibers are carried into the water together with the solid components in the sludge and / or the muddy water to cause the sand. Since it penetrates preferentially from weak spots and voids in the ground, and is finally distributed over the entire sand ground to be reinforced, it is strengthened by the mesh of fine fibers formed over the entire sand ground. Will be carried out more smoothly. In particular, when the pulp fibers contained in the waste liquid of the paper industry or pulp fibers obtained from waste paper are used as the fine fibers in the present invention, the waste pulp or waste paper, which has been a problem in its handling, is a useful resource. Can be reused.

Further, in the present invention, when sludge and / or muddy water in which one or more of a thickener, a surfactant, a coagulant and a water reducing agent are mixed together with fine fibers is used, The fibers are uniformly dispersed in the sludge and / or muddy water without settling, and the solid components contained in the sludge and / or muddy water are prevented from settling, and the solid components in the sludge and / or muddy water are pressed and penetrated. Aggregation at the location where the sand is formed is promoted, and the strengthening of the sand ground can be further promoted.

When it is difficult to press fit fine fibers and, if necessary, one or more kinds of the above-mentioned other components into sludge and / or muddy water into the sand ground, simultaneously with the press-fitting operation or press-fitting. If vibration is applied alternately to the work, the press-fitting can be smoothly performed.

[Brief description of drawings]

FIG. 1 is a vertical view showing an example of a case where a sludge is press-fitted into a sand ground 1 formed by a landfill on a shore such as a sea or a river for reinforcement.

FIG. 2 is a view from above showing an example of a case where sludge is press-fitted into the sand ground 1 formed by landfilling on the shore of a sea or a river for reinforcement.

FIG. 3 is a diagram showing an example of a case where a barrier wall is embedded in the sand ground and sludge and / or muddy water mixed with fine fibers are press-fitted into a region surrounded by the barrier wall.

[Fig. 4] Inserting and burying a pipe in the sand ground from the horizontal direction,
It is a figure which shows the example at the time of performing the press fit of the sludge and / or muddy water which mixed the fine fiber etc. from a horizontal direction.

FIG. 5 is a diagram showing an example of a structure of a pipe used for press-fitting sludge and / or muddy water in which fine fibers and the like are mixed.

[Explanation of symbols]

 1 Sand Ground 2 High-rise Building 3 Pipe 3 3a Outer Pipe 3b Inner Pipe 4 Opening 5 Dredger 6 Bottom of Sea or River 7 Pipe 8 High Pressure Pump 9 Tank 9 10 Pipe 11 Blocking Wall

Claims (4)

[Claims] 1. A method for strengthening a sand ground, which comprises pressurizing sludge and / or muddy water mixed with fine fibers into the sand ground. 2. Sludge and / or muddy water in which one or more of a thickener, a surfactant, a coagulant and a water reducing agent are mixed together with fine fibers are pressed into the sand ground. How to strengthen the sand ground. 3. When press-fitting fine fibers and optionally sludge and / or muddy water containing one or more of a thickener, a surfactant, a coagulant and a water-reducing agent into the sand ground. The method for strengthening a sand ground according to claim 1 or 2, wherein further vibration is applied simultaneously with the press-fitting work or alternately with the press-fitting work. 4. The method for reinforcing a sand ground according to claim 3, wherein vibration is applied by sound waves and / or compressed air.