JP3752672B2 - Construction method of underground improvement body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for constructing an underground improvement body in which a cement-based solidifying agent is mixed while stirring the underground to construct an improvement body made of soil cement in the ground. The built underground improvement body can be formed into a columnar shape and used as a building foundation, or formed into a planar shape as an underground wall, or used as a ground improvement.
[0002]
[Prior art]
The ground improvement body made of soil cement cuts the ground toward the ground, injects the cement-based solidifying agent into the soil generated by the cutting, and stirs the soil and the cement-based solidifying agent in the hole created by the cutting. The soil cement made by mixing is solidified and constructed.
In this method of constructing an underground improvement body, the soil obtained by cutting the ground in the ground and the cement-based solidifying agent are mixed efficiently and uniformly, and the cement-based solidifying agent is homogeneous throughout the soil cement. It is preferred to construct improvements.
As a method of stirring and mixing the cement-based solidifying agent in the agitating soil, for example, injection mixing performed by jet injection or mechanical stirring mixing performed by rotating a stirring blade disposed on a hollow rod such as a steel pipe is known. Yes.
At this time, in the jet mixing, the cement-based solidifying agent is mixed in the jet jet, and the cement-based solidifying agent is mixed together with stirring of the cut soil. In the mechanical stirring and mixing, when the soil is stirred by the rotation of the stirring blade, mixing is performed by injecting a cement-based solidifying agent from the hollow rod.
In the agitation and mixing method of these cut soil and cement-based solidifying agent, for example, in the case of agitation by injection mixing, the injection pressure, the injection method, etc. are devised, or in the case of mechanical agitation mixing, for example, the shape and number of the agitation blades Efforts have been made to increase the stirring and mixing efficiency by devising the mounting angle, rotation speed, and the like.
In addition, as a means for protecting the head of the underground improvement body from damage due to load or the like, it is known to arrange a reinforcing cylinder made of resin or the like on the soil cement head.
Furthermore, in the construction method of the underground improvement body, a known pump is provided from within a plant equipped with an agitator or the like that can be stored so as not to solidify the cement-based solidifying agent for transferring the cement-based solidifying agent to the site where stirring and mixing are performed. , Using a known pipe line such as a hose and the like to the supply port located at the tip of the hollow rod or the jet injection device. In this case, particularly in summer, the viscosity of the slurry made of the cement-based solidifying agent may increase.
[0003]
[Problems to be solved by the invention]
The conventional method for constructing an underground improvement body has the following problems.
<A> In order to uniformly mix the cement-based solidifying agent into the ground by spray mixing, it is necessary to increase the size and functionality of the spray device in order to obtain a high spray pressure and a special spray method.
<B> In order to uniformly mix the cement-based solidifying agent into the ground by mechanical stirring and mixing, when adding a device to the shape and mounting angle of the stirring blade, the stirring blade can only withstand the resistance of soil stirring. It is necessary to adopt materials and structures that can provide rigidity.
Further, in order to uniformly mix the cement-based solidifying agent in the ground with the number of revolutions of the stirring blade, it is necessary to increase the size and performance of the stirring device if the rotation speed of the stirring blade is to be increased.
<C> In order to stir and mix the cement-based solidifying agent into the ground by these means, it is inevitable that the stirring work will be prolonged.
<D> In order to uniformly mix the cement-based solidifying agent into the soil, there is a limit to the above-described devices applied to spray mixing and mechanical stirring and mixing.
<E> Moreover, the resistance of the soil cement at the time of arrange | positioning a reinforcement cylinder body in the predetermined position to the head of the soil cement which is an underground improvement body is large only by stirring and mixing soil.
<F> Especially in the summer, when the viscosity of the slurry composed of a cement-based solidifying agent is improved, the cement-based solidifying agent is solidified in a pipe line such as a plant, a pump, a hose, a hollow rod, or a jet injection device. There is a risk of causing clogging during transfer. Further, when the supply of the cement-based solidifying agent is interrupted or terminated, it is necessary to quickly wash the inside of the pipeline to prevent clogging.
[0004]
OBJECT OF THE INVENTION
The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a method for constructing an underground improvement body which is performed by increasing the fluidity of the cut soil by stirring on site.
Moreover, an object of this invention is to provide the construction method of the underground improvement body which can mix a cement-type solidification agent uniformly in soil.
Moreover, an object of this invention is to provide the construction method of the underground improvement body which can make intensity | strength uniform.
Furthermore, an object of this invention is to provide the construction method of the underground improvement body which can be constructed as it is using the conventional stirring and mixing method.
Furthermore, an object of the present invention is to provide a construction method for an underground improvement body in which a reinforcing cylinder disposed on the head of the underground improvement body can be easily disposed at a predetermined position.
Another object of the present invention is to provide a method for constructing an underground improvement body that prevents solidification of a cement-based solidifying agent during transfer and prevents clogging.
Moreover, an object of this invention is to provide the construction method of the underground improvement body from which the rust prevention effect of the internal peripheral surface of the pipe line which transfers a cement-type solidification agent is acquired.
The present invention achieves at least one of these objects.
[0005]
[Means for Solving the Problems]
In order to solve the problems as described above, the construction method of the underground improvement body of the present invention is a construction method of the underground improvement body that is constructed by mixing the cement-based solidifying agent while stirring the ground with a stirring blade. , Spraying a fluidizing agent into the ground to be stirred, then stirring the earth and sand while cutting the ground with a stirring blade, increasing the fluidity in the ground with the fluidizing agent, and into the stirred ground A cement-based solidifying agent is sprayed, and then the cement-based solidifying agent is stirred and mixed with the stirring blade, thereby constructing an improved body made of soil cement in the ground.
Here, the “cement-based solidifying agent” refers to a known solidifying agent for cement paste such as cement milk or mortar.
[0006]
Further, the construction method of the underground improvement body of the present invention is the construction method of the underground improvement body which is constructed by mixing the cement-based solidifying agent while stirring the ground with a stirring blade. prior to stirring and mixing of the solidifying agent injecting fluidizing agent, a cement solidifying agent was injected into the ground which injects the fluidized agent, followed by sediment while cutting the ground by stirring blade stirring the flow The fluidity in the ground is increased by an agent, and the cement-based solidifying agent is stirred and mixed to construct an improved body made of soil cement in the ground.
[0007]
Also, how to build underground improvement of the present invention is the method for constructing underground improved body to build a mixture of cement solidifying agent while stirring the ground at a stirring blade, in the ground to the agitation, flow Cement in which soil is agitated while spraying the agent, and then the ground is being cut with a stirring blade, the fluidity in the ground is increased by the fluidizing agent, and the fluidizing agent is added in advance to the stirred ground The solidifying agent is sprayed , and then the cement-type solidifying agent is stirred and mixed with the stirring blade, thereby constructing an improved body made of soil cement in the ground .
[0008]
Furthermore, the construction method of the underground improvement body of the present invention is constructed by constructing the underground improvement body by the above-described construction method of the underground improvement body and disposing the reinforcing cylinder on the head of the underground improvement body. It is characterized by doing.
Here, the “reinforcing cylinder” is a cylindrical cylinder formed by combining, for example, a group of resin-made wire rods processed into a wavy shape in order to increase the outer surface area (contact area with the soil cement). The member exhibits a configuration in which soil cement can enter the interior thereof. Moreover, the other similar cylinder body which exhibits the structure which enables the increase of the said surface area and soil cement penetration | invasion is pointed out.
[0009]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
In an embodiment of the present invention, for example, in a building foundation such as a house, a method for constructing a columnar underground improvement body made of soil cement used for a lower part of a foundation that supports a structure will be described as an example.
[0010]
<I> Construction means of the underground improvement body The underground improvement body is constructed by jet mixing using jet injection or mechanical stirring mixing using a stirring blade.
Here, mechanical stirring and mixing will be described as an example.
Construction of the underground improvement body by mechanical stirring and mixing is, for example, provided with a supply port 30 capable of supplying a fluidizing agent 1 and a cement-based solidifying agent 2 described later at the tip, and a stirring blade 31 for cutting the ground on the outer periphery. A hollow rod 3 made of a steel pipe or the like is used. In FIG. 1, the stirring blades 31 other than the stirring blade 31 disposed near the tip of the hollow rod 3 are omitted.
The hollow rod 3 provided with the stirring blade 31 is given a rotational force necessary for stirring and a pressure input to the ground by a known pile driving machine 4.
The fluidizing agent 1 and the cement-based solidifying agent 2 are supplied to the hollow rod 3 by supplying the fluidizing agent 1 and the cement-based solidifying agent 2 in the plant 7 via a hose 71 with a known pump 70. 3 to pump.
[0011]
<B> The fluidizing agent fluidizing agent 1 is added to increase the fluidity of the cut soil 50 and the cement-based solidifying agent 2.
As the fluidizing agent 1, a known ionic surfactant such as an anion, a cation or an amphoteric surfactant or a known nonionic surfactant is used. In addition, high-performance AE water reducing agents, non-separating agents, siliceous materials, high fine powders such as limestone and slag, and agents such as fluidizing agents can also be used. By mixing the fluidizing agent 1 into the ground, the internal friction angle and the adhesive force of the soil 50 can be reduced and the fluidity of the soil 50 can be increased. Moreover, by mixing with the cement-type solidifying agent 2, the fluidity can be improved by preventing the viscosity of the slurry of the cement-type solidifying agent 2 from being increased, and the mixing efficiency of the cement-type solidifying agent 2 in the ground can be increased.
The fluidizing agent 1 includes those obtained by combining a known retarder with the aforementioned agent.
[0012]
<C> Construction of underground improvement body First, the hollow rod 3 provided with the stirring blade 31 is set in the pile driving machine 4, and the pile rod 4 gives a rotational force and pressure input to the underground to the hollow rod 3. At the same time as the cutting of the ground 5 is started, the fluidizing agent 1 and the cement-based solidifying agent 2 accommodated in the plant 7 are pumped by the pump 70 to the hollow rod 3 via the hose 71, and the supply port at the tip of the hollow rod 3 is supplied. It injects from 30 toward the ground 5.
Subsequently, while the ground 5 is being cut by the stirring blade 31 of the hollow rod 3, the generated soil 50 is stirred, and the fluidizing agent 1 and the cement-based solidifying agent 2 to be injected are mixed. Thereby, the fluidity | liquidity of the cut soil 50 and the cement-type solidification agent 2 to inject can be improved.
At this time, for example, the surfactant which is the fluidizing agent 1 is adsorbed to the cut soil 50, and the internal friction angle and the adhesive force of the soil 50 are reduced, thereby improving the fluidity. Alternatively, the surfactant is adsorbed to the cement molecules of the soil 50 and the cement-based solidifying agent 2 by appropriately adjusting the amount of the surfactant of the fluidizing agent 1 mixed with the soil 50 and the cement-based solidifying agent 2. The soil cement 6 having high fluidity as a whole can also be obtained.
As described above, when the fluidity of the cut soil 50 is increased, the mixing efficiency of the cement-based solidifying agent 2 to the stirring soil 50 can be increased, and the soil cement 6 in which the cement-based solidifying agent 2 is uniformly mixed is formed. Can do.
Thus, the ground improvement body which consists of columnar soil cement 6 in the ground by press-fitting the hollow rod 3 downward by the pile driving machine 4 while stirring and mixing the fluidizing agent 1 and the cut soil 50. Build up.
[0013]
Further, in the above-described method for constructing the underground improvement body, at least one of the fluidizing agent 1 or the cement-based solidifying agent 2 is first jetted and stirred and mixed into the stirring soil 50, and then the other is jetted and stirred and mixed. You may do it.
Furthermore, the fluidizing agent 1 can be added to the cement-based solidifying agent 2 in advance at the construction site or factory, and mixed into the agitated soil 50.
[0014]
<D> Action In the present invention, the fluidity of the soil 50 is improved by injecting the fluidizing agent 1 together with the cement-based solidifying agent 2 to the cut soil 50, and the cement-based solidifying agent 2 is put into the soil cement 6. Uniform mixing is possible.
Thereby, in mechanical stirring and mixing, even when the shape and the mounting angle of the stirring blade 31 are devised, the resistance of the soil 50 acting on the stirring blade 31 by the fluidizing agent 1 is reduced, so that high rigidity is obtained. Adoption of material and structure becomes unnecessary. Thereby, the cost of the stirring blade 31 can be suppressed.
Further, in order to uniformly mix the cement-based solidifying agent 2 with the soil 50, it is necessary to increase the size and function of the stirring device in order to increase the rotation speed of the stirring blade 31. It becomes unnecessary by jetting . Thereby, the cost concerning mechanical stirring and mixing can be suppressed.
Furthermore, by using the fluidizing agent 1, the stirring time by the stirring blade 31 can be shortened. Thereby, shortening of the construction period concerning construction of an underground improvement body can be aimed at.
Although not described in the present embodiment, high injection pressure is also obtained in injection mixing because high fluidity of the soil 50 can be ensured by injecting the fluidizing agent 1 onto the soil 50 as in the case of mechanical stirring and mixing. In addition, it is not necessary to increase the size and functionality of the injection device for obtaining a devised injection method.
Moreover, the stirring time by jet injection can be shortened. Thereby, the effect similar to the mechanical stirring mixing mentioned above is acquired.
[0015]
Further, by mixing the fluidizing agent 1 with the cement-based solidifying agent 2, the fluidizing agent 1 is combined with the cement particles of the cement-based solidifying agent 2, and the viscosity improvement of the slurry made of the cement-based solidifying agent 2 can be suppressed. . That is, the fluidity of the cement-based solidifying agent 2 can be improved.
In particular, in summer when the viscosity of the slurry of the cement-based solidifying agent 2 is improved, in order to prevent clogging of pipes and the like due to the solidification of the cement-based solidifying agent 2, stirring mixing including the injection work of the cement-based solidifying agent 2 It was necessary to work quickly, and it was necessary to wash the inside of the pipeline immediately after injection .
As a countermeasure against this, mixing of the fluidizing agent 1 can suppress an increase in the viscosity of the slurry of the cement-based solidifying agent 2 and reduce the clogging phenomenon in the pipe line of the cement-based solidifying agent 2. This eliminates the need for rigorous construction based on the clogging phenomenon caused by the solidification of the cement-based solidifying agent 2, and enables reliable construction with a margin for each process. Increases nature.
[0016]
Further, by using, for example, a known surfactant as the fluidizing agent 1, a plant 7 that supplies the cement-based solidifying agent 2 when the cutting soil 50 is stirred by utilizing the property that this surfactant is adsorbed on a metal. By supplying the fluidizing agent 1 to the pipes such as the pump 70, the hose 71, the hollow rod 3, and the supply port 30 thereof, the fluidizing agent 1 is adsorbed on the metal portion of the inner peripheral surface of these pipes and becomes oily. A film is formed, and the effect of preventing rust of the inner peripheral surface metal part such as a pipe line is obtained.
[0017]
By using the fluidizing agent 1, the unit water amount of the soil cement can be reduced. If the unit water volume of the stirred soil cement can be reduced, it is possible to reduce drying shrinkage and bleeding of the ground improvement body to be constructed, improve water tightness and durability, and reduce cracks due to heat of hydration. That is, the quality of the underground improvement body can be improved.
[0018]
In the embodiment of the present invention, the above-described actions are obtained by taking, as an example, a method of cutting the ground 5 and injecting the fluidizing agent 1 and the cement solidifying agent 2 at the same time. However, the present invention is not limited to this. The fluidizing agent 1 is mixed with the cutting soil 50 prior to the injection of the cement-based solidifying agent 2, so that the fluidizing agent 1 forms a coating on the metal portion of the inner peripheral surface of the pipe and obtains a rust prevention effect. At the same time, it is combined with the soil particles of the cutting soil 50 to reduce the internal friction angle and the adhesive force, that is, the fluidity of the cutting soil 50 can be increased.
Thereafter, by injecting the fluidizing agent 1 together with the cement-based solidifying agent 2, the fluidizing agent 1 can be bonded to the cement particles to suppress an increase in the viscosity of the slurry of the cement-based solidifying agent 2, thereby improving the fluidity. This can be performed in the same manner as described above.
[0019]
Second Embodiment of the Invention
By arranging the reinforcing cylinder 8 as shown in FIG. 2 on the head of the underground improvement body described in the first embodiment of the invention described above, the strength of the underground improvement body head can be increased.
The reinforcing cylinder 8 is a cylindrical member, for example, a net-like body is produced by knitting a wire made of resin or the like processed into a wavy shape, and this is processed into a plurality of layers so as to form a plurality of layers. Constitute. The reinforcing cylinder 8 is formed by overlapping mesh bodies, and has a space in which the soil cement 6 can enter between the inside and the mesh bodies.
The reason why the wavy wire is used for the mesh body constituting the reinforcing cylinder 8 is to increase the contact area with the soil cement 6 and to improve the adhesion. Further, the reason why the soil cement 6 is configured to be able to enter the inside of the reinforcing cylinder 8 is to enhance the integrity with the soil cement 6 which is solidified and becomes an underground improvement body.
Further, as described in the first embodiment of the present invention, the soil cement 6 has high fluidity due to the fluidizing agent 1, so that the resistance force when the reinforcing cylinder 8 is arranged is small, and the arrangement of the reinforcing cylinder 8 is small. Positioning (for example, the center of the soil cement 6 in FIG. 2) is easy.
[0020]
As shown in FIG. 2, the underground improvement body in which the reinforcing cylinder 8 is disposed on the head supports the load received from the foundation 9 of the building by the soil cement 6 and the reinforcing cylinder 8 when used as a building foundation. To do.
The load received by the reinforcing cylinder 8 can be supported by the supporting force at the bottom 80 which is the contact position in the supporting direction with the soil cement 6 and the frictional force between the outer peripheral surface 81 and the soil cement 6. Thereby, the underground improvement body can exhibit high supporting force by the supporting force of the soil cement 6 and the reinforcing cylinder 8 without the head being destroyed by the load of the building.
[0021]
Embodiment 3 of the Invention
In Embodiment 1 of the invention described above, an example in which the underground improvement body is constructed in a columnar shape having a uniform diameter has been described.
On the other hand, even if the underground improvement body to be constructed is a columnar shape, it is possible to construct an improvement body of a free shape by changing the diameter and dimensions thereof.
In addition to the method for constructing an underground improvement body having a columnar shape, the present invention can be applied to a method for constructing a structure using soil cement, such as a soil cement column wall construction method. Furthermore, it is also possible to improve the ground within a predetermined range of the ground by constructing a plurality of ground improvement bodies close to each other.
[0022]
【The invention's effect】
Since the underground improvement body construction method of the present invention is as described above, the following effects can be obtained.
<I> The fluidity of the cutting soil in which the cement-based solidifying agent is stirred and mixed can be enhanced at the construction site of the underground improvement body.
Thereby, the mixing efficiency of the cement-type solidification agent mixed in soil can be improved.
<B> By increasing the mixing efficiency of the cement-based solidifying agent into the soil, the cement-based solidifying agent can be uniformly mixed throughout the soil cement, and the strength of the completed underground improvement body can be made uniform.
<C> If a fluidizing agent is mixed in the cut soil, a ground improvement body that exhibits the above-described effects can be constructed by a conventional stirring method such as spray mixing or mechanical stirring and mixing.
<D> By increasing the fluidity of the cutting soil, the positioning of the reinforcing cylinder disposed on the head of the soil cement, which is an underground improvement body, becomes easy.
<E> By mixing a fluidizing agent, the fluidizing agent can reduce the internal friction angle and the adhesive strength of the soil, and increase the fluidity of the soil.
Further, by mixing the fluidizing agent, it is possible to suppress an increase in the viscosity of the slurry in which the fluidizing agent is a cement-based solidifying agent, and to prevent the cement-based solidifying agent from prematurely solidifying. Thereby, the clogging phenomenon by the solidification of the cement-type solidification agent in a pipe line etc. can be prevented. Furthermore, since the fluidizing agent is adsorbed on the metal portion on the inner peripheral surface of the pipe and the like to form a film, the rust prevention effect of the pipe and the like is exhibited.
<F> Soil cement It can be applied to the construction of various structures constructed with soil cement such as column walls.
[Brief description of the drawings]
FIG. 1 is an explanatory view of a construction method of an underground improvement body according to the present invention. FIG. 2 is an explanatory view of an underground improvement body provided with a reinforcing cylinder according to a second embodiment of the invention.
DESCRIPTION OF SYMBOLS 1 ... Fluidizer 2 ... Cement type solidifying agent 3 ... Hollow rod 30 ... Supply port 31 ... Stirring blade 4 ... Pile driver 5 ... Ground 50 ... Soil 6 ・ ・ ・ Soil cement

Claims (4)

In the construction method of the underground improvement body that is constructed by mixing the cement-based solidifying agent while stirring the ground with a stirring blade,
Injecting a fluidizing agent into the ground to be stirred,
Next, stirring the earth and sand while cutting the ground with a stirring blade,
Increase fluidity in the ground with the fluidizing agent ,
A cement-based solidifying agent is sprayed into the stirred ground,
Subsequently, stirring and mixing is performed by the stirring blade ,
Building an improved body made of soil cement in the ground,
Construction method of underground improvement body. In the construction method of the underground improvement body that is constructed by mixing the cement-based solidifying agent while stirring the ground with a stirring blade,
In the ground to be stirred, a fluidizing agent is sprayed prior to the stirring and mixing of the cement-based solidifying agent,
Injecting cement-based solidifying agent into the ground where the fluidizing agent is injected,
Next, stirring the earth and sand while cutting the ground with a stirring blade,
Stir and mix the cement-based solidifying agent by increasing the fluidity in the ground with the fluidizing agent,
Building an improved body made of soil cement in the ground,
Construction method of underground improvement body. In the construction method of the underground improvement body that is constructed by mixing the cement-based solidifying agent while stirring the ground with a stirring blade,
Injecting a fluidizing agent into the ground to be stirred ,
Next, stirring the earth and sand while cutting the ground with a stirring blade,
Increase fluidity in the ground with the fluidizing agent,
A cement-based solidifying agent to which a fluidizing agent has been added in advance is jetted into the stirred ground,
Subsequently, the cement-based solidifying agent is stirred and mixed with the stirring blade,
Building an improved body made of soil cement in the ground ,
Construction method of underground improvement body. By constructing the underground improvement body by the construction method of the underground improvement body according to any one of claims 1 to 3,
It is characterized by arranging and constructing a reinforcing cylinder in the head of the underground improvement body,
Construction method of underground improvement body.

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