JP2011074675A - Method for constructing soil cement structure, and the soil cement structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a soil cement structure connected with a soil cement column, on a narrow site. <P>SOLUTION: This method includes: a first step of constructing one of the adjacent soil cement columns; and a second step of excavating a section corresponding to the other soil cement column, by rotating a drilling bit 80 via a rod 70 by means of a rotating device 60 of excavation equipment 10, and of constructing the other soil cement column by agitating sediment and cement milk jetted from a cement milk supply means 90. The excavation equipment 10 is equipped with a vibration exciter 50 for vertically applying an exciting force to the drilling bit 80 via the rod 70. In the second step, the drilling bit 80 is rotated; the exciting force is vertically applied to the drilling bit 80 by the vibration exciter 50; and a section corresponding to the other soil cement column is excavated while a lateral portion of the one soil cement column is cut. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for constructing a soil cement structure in which a plurality of soil cement columns are connected.

  Conventionally, a soil cement wall, in particular, a soil cement column wall formed by connecting cylindrical soil cement columns, is widely used as a retaining wall (see, for example, Patent Document 1). Such a soil cement pillar row wall is constructed integrally by constructing adjacent soil cement pillars so as to partially overlap each other.

JP 2009-57682 A

  However, in order to construct the soil cement columns so as to partially overlap each other as described above, after one soil cement column is hardened, when excavating a portion corresponding to the other soil cement column adjacent thereto. In addition, the side of one of the hardened soil cement columns must be cut. For this reason, it is necessary to use a large apparatus capable of excavating a hard soil cement column as an excavating apparatus, and construction on a narrow site becomes difficult.

  This invention is made | formed in view of said problem, The objective is to enable it to construct | assemble the soil cement structure by which a soil cement pillar is connected in a narrow site.

The method for constructing a soil cement structure according to the present invention is a method for constructing a soil cement structure in which a plurality of soil cement columns are connected, and includes a first step of constructing one of adjacent soil cement columns; By rotating the excavating bit while vibrating, the side portion of the one soil cement column is cut, and the hole is stirred while jetting cement milk to the portion corresponding to the other soil cement column, And a second step of constructing the other soil cement pillar.
The above-mentioned “stirring while drilling cement milk into the portion corresponding to the other soil cement column” means that the cement milk is injected into the portion corresponding to the other soil cement column and the ground is drilled. It includes the case of stirring, and the case of stirring the excavated soil and the cement milk while spraying the cement milk after the portion corresponding to the other soil cement column is shaved and stirred.

  In the method for constructing a soil cement structure, the soil cement structure is formed by connecting three or more soil cement pillars, and in the first step, the soil cement pillars are constructed every other soil cement pillar, In the second step, the remaining soil cement pillars may be constructed.

Further, the plurality of soil cement columns may be constructed in an annular shape.
The soil cement structure of the present invention is constructed by the above method.

  According to the present invention, excavation is performed by rotating the excavation bit while applying an exciter force up and down by the exciter, so even if it is a small excavator, the side portion of the soil cement column constructed in advance The ground can be excavated while cutting. Thereby, even in a narrow site, adjacent soil cement columns can be constructed so as to partially overlap each other, and a soil cement structure in which the soil cement columns are connected can be constructed.

It is a figure which shows a ground improvement apparatus. The detailed structure of a drill bit is shown, (A) is a front view, (B) is a side view, (C) is a top view. It is a figure (the 1) for demonstrating the construction method of the cast-in-place pile of this embodiment. It is FIG. (2) for demonstrating the construction method of the cast-in-place pile of this embodiment. It is a figure (the 3) for demonstrating the construction method of the cast-in-place pile of this embodiment. It is FIG. (4) for demonstrating the construction method of the cast-in-place pile of this embodiment. It is a figure for demonstrating the method to construct | assemble a soil cement wall. It is a vertical sectional view which shows a mode that a soil cement pillar is constructed | assembled.

Hereinafter, an embodiment of a method for constructing a soil cement structure according to the present invention will be described with reference to the drawings. In addition, in the following description, the case where the earth retaining wall for constructing a cast-in-place pile as a soil cement structure is constructed is described as an example.
First, a ground improvement device used for constructing a soil cement structure in the present embodiment will be described. FIG. 1 is a diagram showing a ground improvement device 10. As shown in the figure, the ground improvement device 10 includes a moving mechanism 20 composed of a caterpillar, a pedestal portion 30 installed on the moving mechanism 20, and a guide portion 40 supported by the pedestal portion 30 so as to extend vertically. Exciter 50 attached to guide 40, rod 70 connected to exciter 50, rotating device 60 for rotating rod 70, excavation bit 80 attached to the tip of rod 70, rod 70 And a cement milk supply device 90 for discharging cement milk from the tip of the excavation bit 80 through the inside of the drill bit.

The vibration generating device 50 is a device that transmits a vibration generating force generated by rotating an eccentric weight to the rod 70, for example. The vibration force transmitted to the rod 70 only needs to include at least one component in the vertical direction or the horizontal direction, but when the vibration generator 50 is used, both components are included. The vibration generating device 50 is movable along the guide portion 40 together with the rod 70 and the rotating device 60.
The rotating device 60 is a device that applies a rotational force about the axis to the rod 70.

  2A and 2B show a detailed configuration of the excavation bit 80, where FIG. 2A is a front view, FIG. 2B is a side view, and FIG. 2C is a bottom view. As shown in the drawing, the excavation bit 80 includes a shaft portion 81 connected to the rod 70, a drill blade main body 83 attached to the tip of the shaft portion 81 so as to extend laterally, and a drill blade main body 83. A bit 84 attached, a plurality of stirring blades 82 connected to the shaft portion 81 so as to extend toward the outer periphery, and a bit 85 attached to the tip of the shaft portion 81 are provided. The cement milk supplied through the rod 70 by the cement milk supply device 90 is discharged from the tip of the shaft portion 81.

  The ground improvement device 10 can excavate the ground by the bit 84 attached to the excavation blade main body 83 by rotating the excavation bit 80 through the rod 70 by the rotation device 60. Further, the cement milk is sprayed into the excavation hole by the cement milk supply device 90, and the excavation bit 80 rotates so that the agitating blade 82 mixes and agitates the cement milk and the excavated soil to form a soil cement. Can do.

  Drawing 3A-Drawing 3D are figures for explaining a construction method of a cast-in-place pile of this embodiment. 3A (A) and FIGS. 3B to 3D are vertical cross-sectional views, and FIG. 3A (B) is a cross-sectional view taken along the line II in FIG. 3 (A).

Hereinafter, a method for constructing a cast-in-place pile using the ground improvement device 10 will be described.
First, as shown in FIG. 3A, a cylindrical soil cement wall 100 is constructed at a position corresponding to the periphery of the construction position of the cast-in-place pile. The soil cement wall 100 is formed by connecting a plurality of cylindrical soil cement columns 110 in an annular shape. These soil cement pillars 110 are such that the distance between the centers of adjacent soil cement pillars 110 is smaller than the diameter of the soil cement pillars 110 so that both sides of each soil cement pillar 110 partially overlap the adjacent soil cement pillars 110. Has been built. In addition, the soil cement wall 100 has a lower end reaching a depth lower than the groundwater level.

  As the soil cement pillar 110, for example, when a cast-in-place pile having a diameter of about 2500 mm is constructed, the diameter may be about 600 mm. Further, as will be described later, when a compressive load is applied to the soil cement wall 100 from the surrounding ground, the adjacent soil cement columns 110 can be transmitted between the soil cement columns 110. The width of the overlapping portions (D in FIG. 4B described later) may be, for example, about 150 mm. However, the diameter of the soil cement pillar 110 and the width of the overlapping portion are not limited to these.

  FIG. 4 is a view for explaining a method of constructing such a soil cement wall 100. First, as shown in FIG. 4A, every other soil cement pillar 110A constituting the soil cement wall 100 is constructed.

  FIG. 5 is a vertical sectional view showing how the soil cement pillar 110 is constructed. As shown in the figure, the ground until the lower end reaches the upper part of the support layer 3 while rotating the excavation bit 80 at a speed of 20 to 60 revolutions per minute by the rotation device 60 of the ground improvement device 10 through the rod 70 1 is excavated to form an excavation hole 4. At this time, for example, a vibration force of about 20 to 50 Hz is applied to the excavation bit 80 through the rod 70 by the vibration generator 50. Thereby, since the excavation bit 80 also vibrates up and down, cutting efficiency improves. Moreover, since the excavation bit 80 vibrates up and down and this vibration is transmitted to the ground 1, excavation can be easily performed because large gravel and rock in the ground 1 move by vibration.

  In parallel with the excavation work, cement milk is injected into the excavation hole 4 through the inside of the rod 70 by the cement milk supply device 90. Cement milk is sprayed from the tip of the rod 70 to the ground 1 below the excavation bit 80 and an exciter force is transmitted from the excavation bit 80, so that the ground 1 vibrates in a state containing cement milk. Since it is liquefied and softened, it can be easily cut by the excavation bit 80. As described above, according to the ground improvement device 10, excavation efficiency by the excavation bit 80 is improved by applying an excitation force by the vibration generation device 50.

  Then, the soil cement cut from the excavation bit 80 and the cement milk sprayed from the tip of the rod 70 are agitated by the agitating blade, so that a soil cement is formed in the excavation hole 4.

  Next, as shown in FIG. 4B, a soil cement pillar 110B is newly constructed by the ground improvement device 10 between the soil cement pillars 110A constructed with a space therebetween. When excavating the ground to newly construct the soil cement pillar 110B, the side portion of the adjacent soil cement pillar 110A that has already been constructed is cut. And the adjacent soil cement pillars 110 are integrally connected by mixing and stirring cement milk with excavated soil in the excavation hole.

  At this time, as in the case of excavating the soil cement pillar 110A, the excavating bit 80 is rotated through the rod 70 by the rotating device 60 of the ground improvement device 10 and the excavating device 50 is excavated through the rod 70. An exciting force is applied to the bit 80. Thereby, since the excavation efficiency by the excavation bit 80 is improved, it is possible to excavate the ground while cutting the side portion of the soil cement pillar 110A that has been easily hardened.

  After the annular soil cement wall 100 is constructed in this way, as shown in FIG. 3B, the ground 1 is excavated to a predetermined depth inside the soil cement wall 100 by the excavator 200 to form the excavation hole 130. As the excavator 200, for example, an excavator that can be excavated even in a narrow site, for example, used in the TBH method is suitable. At this time, the inside of the excavation hole 130 is filled with the stabilizing liquid. However, since the soil cement wall 100 surrounds the excavation hole 130 and the soil cement wall 100 has a water-stopping property, To prevent leakage. That is, when there is an underground structure around the site where the cast-in-place pile 300 is to be constructed, if the stable liquid leaks from the excavation hole 130, the stable liquid may enter the underground structure. However, this embodiment can prevent this. Moreover, since the soil cement wall 100 has a water-stopping property, it is possible to prevent the groundwater from seeping out.

  When excavating the ground 1, soil water pressure acts on the soil cement wall 100 from the surrounding ground 1, but since the soil cement wall 100 is formed in an annular shape, it resists this soil water pressure by the ring compression effect. Can do. Moreover, since the soil cement wall 100 has a water-stopping property, it can prevent that groundwater oozes out inside.

  Next, as shown in FIG. 3C, the rebar cage 140 is installed in the excavation hole 130. In addition, it is good to connect the reinforcement | strengthening cage | basket | car 140 previously, what was divided | segmented into the length direction is built.

  Next, as shown in FIG. 3D, the treme tube 210 is inserted into the excavation hole 130, and the concrete 150 is placed in the excavation hole 130 through the treme tube 210. Construction of the cast-in-place pile 300 is completed when the cast concrete 150 is hardened.

  According to the present embodiment, the excavation force is improved by applying an excitation force to the excavation bit 80 by the vibration generation device 50 of the ground improvement device 10. Accordingly, the ground 1 can be excavated while cutting the side portion of the hardened soil cement column 110A. Therefore, the soil cement wall 110 can be constructed by connecting the soil cement columns 110 together.

  Conventionally, a large apparatus has been used to improve the excavation efficiency of the ground improvement device 10. However, in this embodiment, the excavation efficiency is increased by applying an excitation force to the excavation bit 80 of the ground improvement device 10. Since it is improved, it is possible to excavate the ground with high strength even with a small device. For this reason, construction is possible even in a narrow site with high ground strength.

  In addition, in the conventional method, if a ground fault was found during the press-fitting of the steel pipe pile, the construction could not be removed without interrupting the construction and removing the steel pipe pile. According to the present embodiment, the excavation hole is formed in advance, and in this case, since the underground obstacle can be removed, the construction can be performed without interruption.

  In the present embodiment, the excavation bit 80 described with reference to FIG. 2 is used. However, the present invention is not limited to this, and an excavation bit having another shape may be used.

  In this embodiment, every other soil cement column 110 arranged in an annular shape is constructed, and then the remaining soil cement columns 110 are constructed. However, the present invention is not limited to this, and the soil cement columns 110 are arranged in the circumferential direction. The soil cement pillar 110 may be constructed in any order.

  Further, in the present embodiment, the case where the soil cement wall 100 is constructed as a retaining wall when constructing a cast-in-place pile has been described. However, the construction method of the soil cement structure of the present invention can be applied.

Moreover, although this embodiment demonstrated the case where the soil cement structure formed by connecting the soil cement pillar 110 in a ring shape was constructed, it is not limited to this, and the soil cement formed by connecting the soil cement pillars 110 in a row. A structure may be constructed, or in short, the present invention can be applied to constructing a soil cement structure in which soil cement columns are connected.
Further, in this embodiment, when the soil cement pillar 110B is constructed, the ground is drilled and stirred while cement milk is sprayed by the ground improvement device 10, but the present invention is not limited to this, and water is jetted. However, after agitating the hole to a predetermined depth, the excavating soil and cement milk may be agitated by the excavating bit 80 while the cement milk is jetted into the excavating soil when the excavating bit 80 is pulled up.

DESCRIPTION OF SYMBOLS 1 Ground 3 Support layer 4 Excavation hole 10 Ground improvement apparatus 20 Movement mechanism 30 Base part 40 Guide part 50 Exciting apparatus 60 Rotating apparatus 70 Rod 80 Excavation bit 90 Cement milk supply apparatus 100 Soil cement wall 110 Soil cement pillar 130 Excavation hole 150 Concrete 200 Excavator 210 Tremy pipe 300 Cast-in-place pile

Claims (4)

A method for constructing a soil cement structure in which a plurality of soil cement pillars are connected,
A first step of constructing one of the adjacent soil cement columns;
By rotating the excavating bit while vibrating, the side portion of the one soil cement column is cut, and the other side is obtained by stirring the hole while jetting cement milk to the portion corresponding to the other soil cement column. And a second step of constructing the soil cement pillar of the present invention. A method for constructing a soil cement structure according to claim 1,
The soil cement structure is formed by connecting three or more soil cement pillars,
In the first step, every other soil cement pillar is constructed,
In the second step, the remaining soil cement pillar is constructed, and a method for constructing a soil cement structure is provided. A method for constructing a soil cement structure according to claim 1 or 2,
A method for constructing a soil cement structure, wherein the plurality of soil cement columns are constructed in an annular shape.   A soil cement structure constructed by the method according to any one of claims 1 to 3.

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