JP2004285715A - Earth work executing method in soft ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide earth works executing method available in soft ground, which improves the trafficability of an excavator on the soft ground. <P>SOLUTION: According to the method, soil improvement is carried out by excavating the ground G by an excavating shaft 1, adding a hardener 2 and air bubbles 3 to excavated soil S1 in an excavated hole H, followed by mixing them, to thereby obtain improved soil S2. Then earth works are executed by excavating the improved ground G. The excavating shaft may be formed of a drill rod having a screw, a drill rod having a high-pressure jet ejecting hole formed at the tip thereof, or the like. The hardener may be cement milk, for instance, that can improve the strength of the earth when added to the soil. Preferably the hardener 2 and the bubbles 3 are added directly into the excavated earth S1 in the excavated hole H, and then they are mixed in the same. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of earthworks on soft ground for improving the trafficability of an excavating machine on soft ground.
[0002]
[Prior art]
In earthworks on a site where the soft ground is thickly piled up, the excavator may not be able to secure the trafficability due to insufficient strength of the ground relative to the weight of the excavator. Therefore, it is necessary to treat the ground before excavating the ground.
[0003]
FIG. 4 shows an example of a conventional soft ground surface layer treatment method. Examples of this type of construction method include surface drainage, sand mat, laying material construction method, surface soil stabilization treatment method and the like (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-10-140552 [0005]
[Problems to be solved by the invention]
However, since these stabilize the soil quality of the shallow portion G1 (up to about 3 m from the ground surface) of the soft ground G as shown in FIG. 4, the ground is excavated to a depth greater than this (about 5 m or more). In case of excavation, the traffic of the excavator could not be secured.
[0006]
In particular, in the case of excavation work that is performed near the existing structure in urban urban areas, or when the construction scale is large, the ground around the site will not be affected by settlement, etc. In some cases, it is necessary to improve the ground over a wide area including the area around the site, and there has been a problem that construction costs have risen.
[0007]
An object of the present invention is to provide a method for earthworks on soft ground, which can improve the trafficability of an excavating machine on soft ground.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the method of earthworks on soft ground according to the invention of claim 1 is, for example, as shown in FIGS.
The ground G is excavated by the excavation shaft 1, and the solidified material (cement milk) 2 and the air bubbles 3 are added to the excavated soil S1 in the excavation hole H and mixed to form the improved soil S2.
Next, the improved ground G is excavated to perform earthwork.
Here, the drilling shaft may be a drilling rod having a screw, a drilling rod having a high-pressure jet discharge hole at the distal end of the drilling rod, or the like.
In addition, the solidifying material refers to, for example, a chemical liquid such as cement milk or water glass that is used to increase the strength of the soil by being added to the soil.
[0009]
According to the first aspect of the present invention, since the improved soil is formed by adding air bubbles to the excavated soil in addition to the solidifying material, the specific gravity of the improved soil is reduced, and a heavy machine for filling the improved soil into the excavation hole is provided. Burden is reduced. Further, by adding air bubbles in addition to the solidified material to form the improved soil, the fluidity of the improved soil is increased, the improved soil is easily pumped, and the improved soil is more easily filled into the excavation hole.
In addition, in the method of reducing the specific gravity of the improved soil by adding foam beads or the like to the excavated soil, the improved soil may become an industrial waste, but since air bubbles are added instead of this, the impact on the environment is small. Do it.
[0010]
Since the soft ground is excavated after its strength is improved, the stability of the ground to be excavated is secured, and the trafficability of the excavating machine can be enhanced.
Accordingly, deformation of the surrounding ground and deformation of the existing underground structure can be suppressed. Therefore, even in the case of close construction under the condition close to the existing structure, it is not necessary to perform large-scale ground improvement including the surrounding ground.
Further, the strength of the ground after the improvement can be adjusted by increasing or decreasing the amount of the solidifying material so as to secure the trafficability of the excavating machine and not to impair the workability of the excavation. Therefore, the strength of the construction machine can be reduced by setting the strength appropriately so that the ground after the improvement is not too hard or too soft.
In addition, by drilling the excavation hole in the vertical direction with the excavation axis, the strength of the soft ground can be improved whether the layer thickness is thick or thin.
In addition, without improving the entire soft ground, it is possible to drill holes only in necessary places in the plane or in the depth direction with an excavation axis to partially improve the ground, thereby reducing the cost of ground improvement. be able to.
[0011]
The method of earthwork on soft ground according to the invention of claim 2 is, for example, as shown in FIGS.
The ground G is excavated by the excavation shaft 1, and the solidified material (cement milk) 2 is added to the excavated soil S1 in the excavation hole H and mixed to form the improved soil S2.
Next, the improved ground G is excavated to perform earthwork.
[0012]
According to the second aspect of the present invention, since the excavation is performed after the soft ground is improved in strength, the stability of the ground to be excavated is secured, and the trafficability of the excavating machine can be enhanced.
Accordingly, deformation of the surrounding ground and deformation of the existing underground structure can be suppressed. Therefore, even in the case of close construction under the condition close to the existing structure, it is not necessary to perform large-scale ground improvement including the surrounding ground.
Further, the strength of the ground after the improvement can be adjusted by increasing or decreasing the amount of the solidifying material so as to secure the trafficability of the excavating machine and not to impair the workability of the excavation. Therefore, the strength of the construction machine can be reduced by setting the strength appropriately so that the ground after the improvement is not too hard or too soft.
In addition, by drilling the excavation hole in the vertical direction with the excavation axis, the strength of the soft ground can be improved whether the layer thickness is thick or thin.
In addition, without improving the entire soft ground, it is possible to drill holes only in necessary places in the plane or in the depth direction with an excavation axis to partially improve the ground, thereby reducing the cost of ground improvement. be able to.
[0013]
The invention according to claim 3 is, for example, as shown in FIG.
The solidified material 2 and the bubbles 3 are added to the excavated soil S1 and mixed in the excavated hole H.
Here, in order to add and mix the solidified material and bubbles to the excavated soil in the excavation hole, for example, when excavating the ground with a drilling rod having a high pressure jet emission hole at the tip, cement is removed from the high pressure jet emission hole. A method in which air bubbles are turbidized in a solidified material such as milk is injected at a high pressure and mixed with excavated soil by rotating a screw or a bit of a drilling rod. The mixing can also be performed by a horizontal stirring blade, a vertical rotation stirring blade, a chain-saw endless track stirring blade, or the like.
[0014]
According to the third aspect of the present invention, the same effect as that of the first aspect of the invention can be obtained, and at the same time when the ground is excavated with the excavation axis, the solidified material and the air bubbles are added to the excavated soil in the excavation hole. Is added and mixed, construction can be performed in a short time and in a small space.
[0015]
The invention described in claim 4 is, for example, as shown in FIG.
The solidified material is added to and mixed with the excavated soil S1 in the excavation hole H.
Here, in order to add and mix the solidified material to the excavated soil in the excavation hole, for example, when excavating the ground with a drilling rod having a high-pressure jet discharge hole at the tip, cement milk or the like is discharged from the high-pressure jet discharge hole. A method of injecting the solidified material at high pressure and mixing it with excavated soil by rotating the screw or bit of the drilling rod is used. The mixing can also be performed by a horizontal stirring blade, a vertical rotation stirring blade, a chain-saw endless track stirring blade, or the like.
[0016]
According to the fourth aspect of the invention, the same effect as the second aspect of the invention can be obtained, and at the same time when the ground is excavated with the excavation axis, the solidified material is added to the excavated soil in the excavation hole. The mixing can be performed in a short time and in a small space.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, with reference to the drawings, an embodiment of a method of earthworks on soft ground according to the present invention will be specifically described.
The method of earth work on soft ground in each embodiment is performed under the condition that the excavation work is performed in the vicinity of an existing structure in an urban area or when the scale of the work is large. The purpose of this project is to improve the trafficability of construction machinery in earthworks and to prevent the ground around the site from subsidence, etc., when the target ground is soft.
[0018]
[First Embodiment]
The method of earthwork on soft ground according to the present embodiment will be described with reference to FIG.
First, the ground G is excavated by the excavating shaft 1 provided with the screw while performing high-pressure jet water discharge from the tip of the excavating shaft 1 to the side.
[0019]
When the target excavation depth is reached by the screw and the high-pressure jet water, the excavation shaft 1 is pulled out. At the same time, the excavated soil S1 is sucked from the excavation hole H to the mixing plant 4 above the ground through the pipe of the excavation shaft core.
[0020]
In the mixing plant 4, the improved excavated soil S2 is obtained by adding the cement milk (solidified material) 2 and the air bubbles 3 to the excavated excavated soil S1 and mixing and stirring.
The amount of unit cement in the improved soil S2 is adjusted in accordance with the water content in the excavated soil S1 and the amount of the air bubbles 3 added, and the improved soil S2 is necessary for ensuring the trafficability of the construction machine used in the ground G. Make sure it is strong enough.
The bubbles added to the improved soil S2 are for facilitating pumping when the improved soil S2 is returned to the excavation hole H thereafter. The unit volume weight of the improved soil S2 is about 1.1 to 1.2 t / m3, which is lighter than general soil including cohesive soil.
[0021]
As shown in FIG. 1, the improved soil S2 is pumped into the excavation hole H and driven.
By repeating this operation, the excavated soil S1 from the ground G is processed into improved soil S2, which is poured.
When the ground G is viewed from above, the ground G is in a state as shown in FIG. The ground G improved in this way is excavated by an excavator, and earthwork is performed on the ground G.
[0022]
[Second embodiment]
The method for earthworks on soft ground according to the present embodiment is a modification of the first embodiment, which simplifies the process. The description of the points common to the first embodiment will be omitted, and the description will focus on the differences.
[0023]
The method of earthwork on soft ground according to the present embodiment will be described with reference to FIG.
First, the ground G is excavated while the cement milk (solidified material) 2 in which the bubbles 3 are turbid is discharged from the high-pressure jet hole to the side from the tip of the excavation shaft 1 by the excavation shaft 1 having the screw. To go.
[0024]
In the process of excavating the ground G, the screw and the bit of the excavation shaft 1 are rotated, so that the excavated soil S1 in the excavation hole H and the cement milk 2 in which the bubbles 3 are turbid are mixed and stirred.
[0025]
When reaching the target excavation depth, the excavation axis 1 is pulled out. Thereby, as shown in FIG. 3, the improved soil S2 is poured into the excavation hole H of the ground G.
By repeating this operation, the excavated soil S1 from the ground G is processed into improved soil S2, which is poured.
When the ground G is viewed from above, the ground G is in a state as shown in FIG. The ground G improved in this way is excavated by an excavator, and earthwork is performed on the ground G.
[0026]
According to the method of earthwork on soft ground in each of the above embodiments, the excavated soil S1 is added with the foam 3 in addition to the cement milk 2 to form the improved soil S2, so that the specific gravity of the improved soil S2 is reduced, The burden on the heavy equipment when filling the improved soil S2 into the excavation hole H is reduced. In addition, by adding the air bubbles 3 in addition to the cement milk 2 to form the improved soil S2, the fluidity of the improved soil S2 is increased, and the improved soil S2 is easily pumped and pumped into the excavation hole H of the improved soil S2. Is improved.
In addition, in the method of reducing the specific gravity of the improved soil by adding foam beads or the like to the excavated soil, the improved soil may become an industrial waste, but since the air bubbles 3 are added instead, the influence on the environment is reduced. Small enough.
[0027]
Since the soft ground G is excavated after its strength is improved, the stability of the ground G to be excavated is secured, and the trafficability of the excavating machine can be enhanced.
Accordingly, deformation of the surrounding ground and deformation of the existing underground structure can be suppressed. Therefore, even in the case of close construction under the condition close to the existing structure, it is not necessary to perform large-scale ground improvement including the surrounding ground.
In addition, the strength of the ground after the improvement can be adjusted by increasing or decreasing the amount of unit cement in the improved soil S2 so as to secure the trafficability of the excavating machine and not to impair the workability of the excavation. Accordingly, the ground G after the improvement is appropriately strengthened so as not to be too hard or too soft, and the load on the construction machine can be reduced.
In addition, by drilling the excavation hole H in the vertical direction with the excavation shaft 1, the strength of the soft ground G can be improved whether the layer thickness is thick or thin.
Further, only the necessary portions can be drilled with the excavating shaft 1 to partially improve the ground without improving the entire soft ground G, so that the cost of the ground improvement can be reduced.
[0028]
In addition, according to the method of earthwork on soft ground according to the second embodiment, at the same time when the ground G is excavated with the excavation shaft 1, the cement milk 2 and the air bubbles 3 are formed in the excavated soil S1 in the excavation hole H. Is added and mixed, construction can be performed in a short time and in a small space.
[0029]
In addition, the method of earthwork on soft ground of the present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention. good.
For example, if a surfactant or the like is added to the excavated soil S1, bubbles in the improved soil S2 can be effectively generated.
In addition, it is needless to say that specific detailed structures and the like can be appropriately changed.
[0030]
【The invention's effect】
According to the first aspect of the present invention, since the improved soil is formed by adding air bubbles to the excavated soil in addition to the solidifying material, the specific gravity of the improved soil is reduced, and a heavy machine for filling the improved soil into the excavation hole is provided. Burden is reduced. Further, by adding air bubbles in addition to the solidified material to form the improved soil, the fluidity of the improved soil is increased, the improved soil is easily pumped, and the improved soil is more easily filled into the excavation hole.
In addition, in the method of reducing the specific gravity of the improved soil by adding foam beads or the like to the excavated soil, the improved soil may become an industrial waste, but since air bubbles are added instead of this, the impact on the environment is small. Do it.
[0031]
Since the soft ground is excavated after its strength is improved, the stability of the ground to be excavated is secured, and the trafficability of the excavating machine can be enhanced.
Accordingly, deformation of the surrounding ground and deformation of the existing underground structure can be suppressed. Therefore, even in the case of close construction under the condition close to the existing structure, it is not necessary to perform large-scale ground improvement including the surrounding ground.
Further, the strength of the ground after the improvement can be adjusted by increasing or decreasing the amount of the solidifying material so as to secure the trafficability of the excavating machine and not to impair the workability of the excavation. Therefore, the strength of the construction machine can be reduced by setting the strength appropriately so that the ground after the improvement is not too hard or too soft.
In addition, by drilling the excavation hole in the vertical direction with the excavation axis, the strength of the soft ground can be improved whether the layer thickness is thick or thin.
In addition, without improving the entire soft ground, it is possible to drill holes only in necessary places in the plane or in the depth direction with an excavation axis to partially improve the ground, thereby reducing the cost of ground improvement. be able to.
[0032]
According to the second aspect of the present invention, since the excavation is performed after the soft ground is improved in strength, the stability of the ground to be excavated is secured, and the trafficability of the excavating machine can be enhanced.
Accordingly, deformation of the surrounding ground and deformation of the existing underground structure can be suppressed. Therefore, even in the case of close construction under the condition close to the existing structure, it is not necessary to perform large-scale ground improvement including the surrounding ground.
Further, the strength of the ground after the improvement can be adjusted by increasing or decreasing the amount of the solidifying material so as to secure the trafficability of the excavating machine and not to impair the workability of the excavation. Therefore, the strength of the construction machine can be reduced by setting the strength appropriately so that the ground after the improvement is not too hard or too soft.
In addition, by drilling the excavation hole in the vertical direction with the excavation axis, the strength of the soft ground can be improved whether the layer thickness is thick or thin.
In addition, without improving the entire soft ground, it is possible to drill holes only in necessary places in the plane or in the depth direction with an excavation axis to partially improve the ground, thereby reducing the cost of ground improvement. be able to.
[0033]
According to the third aspect of the present invention, the same effect as that of the first aspect of the invention can be obtained, and at the same time when the ground is excavated with the excavation axis, the solidified material and the air bubbles are added to the excavated soil in the excavation hole. Is added and mixed, construction can be performed in a short time and in a small space.
[0034]
According to the fourth aspect of the invention, the same effect as the second aspect of the invention can be obtained, and at the same time when the ground is excavated with the excavation axis, the solidified material is added to the excavated soil in the excavation hole. The mixing can be performed in a short time and in a small space.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a method of earthworks on soft ground according to the present invention.
FIG. 2 is a top view showing a state of ground improvement by an example of a method of earthworks on soft ground according to the present invention.
FIG. 3 is a schematic view showing another example of the method of earthworks on soft ground according to the present invention.
FIG. 4 is a schematic view showing an example of a conventional soft ground surface treatment method.
[Explanation of symbols]
Reference Signs List 1 excavation axis 2 solidified material 3 bubble G ground H excavation hole S1 excavated soil S2 improved soil

Claims (4)

While excavating the ground with a drilling axis, solidification material and air bubbles are added to the excavated soil in this excavation hole and mixed to form an improved soil, and the soil is improved,
Next, a method of earthworks on soft ground characterized by excavating the improved ground to perform earthworks. The ground is excavated by the excavation axis, and the solidified material is added to the excavated soil in this excavation hole and mixed to form an improved soil, thereby improving the ground.
Next, a method of earthworks on soft ground characterized by excavating the improved ground to perform earthworks. The method according to claim 1, wherein the solidified material and the air bubbles are added to the excavated soil and mixed in the excavation hole. The method according to claim 2, wherein the solidified material is added to and mixed with the excavated soil in the excavation hole.

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