JPS63125722A - Construction of underground continuous wall - Google Patents

Abstract

PURPOSE:To avoid the occurrence of escaping phenomenon or avoidance of hard concrete by excavator by a method in which a wide aperture is formed between preceding elements, and excavation is made under the guidance of the wide aperture for the excavator. CONSTITUTION:A spacer box 5 is set on at least upper end of an excavated ground in the direction of joining an excavated pit 1 for forming preceding element and concrete 4 is placed to form the preceding element. After the concrete hardens, the spacer box 5 is removed away to form a wide interval with a great end spacing between the preceding elements. Under the guidance of the wide interval for excavator, excavation is made between the two preceding elements.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of constructing an underground continuous wall constructed by forming elements (walls) underground and connecting these elements.

``Prior art'' Underground continuous walls constitute earth retaining walls, water-stopping walls, foundations of structures, underground structures, etc., and the following are the commonly used construction methods: I have something to say.

First, two preceding elements (wall bodies) constituting a part of the continuous wall are formed in the ground, separated from each other by approximately the length of one element. These preceding elements are
After constructing an excavated hole to form the preceding element, a reinforcing steel cage is erected in the excavated hole, and concrete is poured therein to construct the structure. Once the preceding elements have been constructed, an excavation hole for the succeeding element is constructed by excavating between the two preceding elements. However, at the same time as this excavation, the end face of the preceding element facing the drilling hole for the following element is cut to a predetermined size (usually 10 cm).
Before and after) Cut and remove. This is to remove slime adhering to this end face and to roughen the so-called joint surface. After that, a reinforcing cage is erected in the excavated hole for the trailing element and concrete is poured to form the trailing element, and by connecting the preceding element and the trailing element, a continuous wall is created underground. It is about forming.

"Problems to be Solved by the Invention" By the way, in the conventional construction method described above, when constructing an excavation hole for the following element between the two preceding elements, the excavator is placed exactly in the middle between the two preceding elements. By positioning the element and digging downward, the end face of the preceding element in the pouring direction is also attempted to be cut to a predetermined dimension at the same time. However, since the preceding element is made of concrete, it is difficult to cut the end face of the preceding element in the pouring direction, especially at the initial stage of excavation. , that is, the drilling drill of the excavator is hooked on the upper end of the two preceding elements,
When attempting to start excavating and cutting the end face of the element, the excavator does not engage the hard concrete smoothly, resulting in so-called escape. For this reason, there is a risk that not only the positional shift may occur and a correct cutting line cannot be ensured, but also that the stability of the excavator may be compromised, resulting in unbalanced loads.

The present invention has been made in view of the above circumstances, and when forming an excavated hole for the trailing element between two leading elements while cutting the end face of the leading element,
The object of the present invention is to provide a method for constructing an underground continuous wall that allows smooth positioning of an excavator and thereby realizes stable excavation.

"Means for solving the problem" The present invention divides the underground continuous wall to be constructed into a plurality of elements in the direction of the construction force, and drills holes for forming the preceding elements at regular intervals in advance. After forming a leading element by pouring concrete into the excavated hole, use an excavator to excavate between these leading elements, and at the same time cut the end face of the leading element in the pouring direction to a dimension of ρ for use as a trailing element. In a method for constructing a continuous underground wall, the continuous wall is constructed by excavating a hole and pouring concrete into the excavated hole to form a succeeding element that is continuous with the preceding element. A step of pouring concrete with a spacer box having a thickness of ρ interposed at least at the upper end of the excavation end face in the pouring direction of the excavated hole to form a preceding element, and removing the spacer box after the concrete has hardened. The present invention is characterized by comprising a step of forming a wide gap between the elements with a large distance between their end faces, and a step of excavating between two preceding elements using the wide gap as a guide for the excavator.

"Operation" At the initial stage of drilling between the preceding elements, the positioning and stabilization of the excavator is ensured, thereby ensuring an accurate excavation line.

"Embodiments" Examples of the present invention will be described below with reference to FIGS. 1 to 7.

First, as shown in Figure 1, the drilling hole l for the preceding element.
excavate. The depth and width (wall thickness) of this excavated hole 1 are the same as the dimensions of the intended continuous wall, and the length (width in the pouring direction) is several meters.

Once the excavated hole l for the preceding element has been constructed, the reinforcing bar cage 2 is erected in this excavated hole l, and then concrete 4 is poured using the tremie pipe 3. A spacer box 5 is attached to the upper part of the excavated wall surface 1a in the direction of joining. The spacer box 5 is the fourth
As shown in the figure, it is in the form of a plate, and in the example, the width is approximately equal to the excavation wall surface la, and the thickness is the cutting dimension Q ( In the example, the length is approximately equal to approximately 10 cm), and the length is approximately 5 cm.
It belongs to m. Also, this spacer box 5
is provided with a fixing head 5a at its upper end so that it is attached to the excavated hole l and does not come off.

When the poured concrete 4 hardens and the leading element 6 is formed as shown in FIG. 2, the spacer box 5 is pulled out and removed. As a result, a space 7 equal to the thickness of the spacer box 5 is formed in the upper part of the preceding element 6 at both ends thereof in the middle direction, as shown in FIG.

Once the preceding element 6 as described above is formed, as shown in FIG. 5(a), a similar preceding element 6 is formed.
It is formed at a predetermined interval from the preceding element 6 using the same procedure as described above. The spacing provided between the two preceding elements at this time is as follows. This is related to the subsequent element described later. That is, a trailing element is formed between the two leading elements 6, and for this purpose, an excavated hole 8 for the trailing element is constructed between the leading elements 6, as shown in FIG. 5(b).

At the same time as this excavation, the end faces 6a of the leading elements 6 on both sides in the joining direction are cut and removed by the required size.
If this cutting dimension is ρ, the two preceding elements 6
The distance A is 2Q shorter than the width B excavated by an excavator (described later). Since the two formed leading elements 6 each form the space 7 above, the concrete portion forming the leading element 6 is a wide-spaced part in which the distance between the mutual end faces is large in the upper part. 9.

Next, as shown in FIG. 6, in order to form a trailing element, an excavator 10 is installed at the center between these leading elements and excavation is started from the upper part thereof. At this time, cutting of the splicing end surfaces 6a of these preceding elements 6 is not performed in the initial stage of this excavation. This is because the interval between the wide interval portions 9 is approximately equal to the width of the excavator IO. As a result, positioning can be performed smoothly without causing so-called escape of the cutting edge, where the excavator does not bite into hard concrete. Moreover, the wide spaced part 9, which is approximately halfway between the excavator IO and the excavator 1,
This serves as a guide when the excavator 1 excavates downward.
0 can not only maintain a vertical posture and perform stable excavation (but also the end face 6a of the preceding element in the pouring direction).
It is possible to ensure an accurate cutting line even when removing the material by cutting, that is, it is possible to reliably cut the required Q dimension evenly.

Once the excavation hole 8 for the trailing element is formed by the excavator 10, a reinforcing bar cage is installed in the excavation hole 8 by conventional means, and then concrete is poured to form the trailing element to connect to the leading element. ) 11 may be formed. Thereafter, the following elements 11 may be formed between the preceding elements 6, which are formed intermittently, in the same manner as described above, to complete the underground continuous wall W.

FIG. 8 shows another embodiment of the present invention, and this embodiment also includes:
A case is shown in which a cylindrical structure 12 is constructed using an underground continuous wall W. In order to make the cylindrical structure 12 as close to a perfect cylinder as possible, when it is constructed using so-called rectangular bodies such as elements, it is necessary to make the number of polygons as large as possible. It is desirable to provide an angle between each element. That is, when forming the trailing element 11 on the leading element 6, an angle is also formed between them.

Now, FIG. 8 shows that two leading elements 6 are formed at a predetermined interval and at a predetermined angle. Between these leading elements 6, a drilled hole 8 for the trailing element is formed on the end face 6a of the leading element in the splicing direction.
Excavation is performed while cutting, but at that time, because the end faces 6a of the two preceding elements 6 in the pouring direction are not parallel, the dimensions of the cut and removed portion 13 differ between the inside and outside of the continuous wall W. Become something. In other words, the cross section is cut and removed in a substantially trapezoidal shape. Therefore, in such a case, when forming the preceding element 6, a spacer box 5 having substantially the same cross-sectional shape as the cut-out portion 13 is used as the spacer box 5 shown in the first embodiment. By doing so, when the two preceding elements 6 are formed and the spacer box 5 is removed, the joining surfaces 6b forming the wide-spaced portion 9 can be parallel. Therefore, similarly to the first embodiment, the excavator 1
0 (not shown in FIG. 8) does not start cutting the cutting and removing portion 13 from the initial stage of excavation, and stable excavation can be performed using the wide-spaced portion 9 as a guide.

In the example, the length of the spacer box is approximately 5 m, but the length of the spacer box is not limited to this, and may be long enough to sufficiently stabilize the excavator IO. ) may be used as long as it has a length that forms the wide-spaced portion 9.

"Effects of the Invention" As explained above, the present invention divides the underground continuous wall to be constructed into a plurality of elements in the construction direction, and forms excavated holes for forming the preceding elements at regular intervals in advance. After pouring concrete into the excavated hole to form a leading element, an excavator is used to excavate between these leading elements, and at the same time, the end face of the leading element in the pouring direction is cut to a dimension σ to form a hole for the trailing element. In a method for constructing a continuous underground wall, in which a continuous wall is constructed by excavating a hole and pouring concrete into the excavated hole to form a subsequent element that is continuous with the preceding element, A step of pouring concrete with a spacer box having a thickness of ρ interposed at at least the upper end of the excavated end face in the pouring direction of the excavated hole to form a preceding element, and removing the spacer box after the concrete hardens to form the preceding element. The method includes a step of forming a wide spaced part having a large end face distance between them, and a step of excavating between the two preceding elements using the wide spaced part as a guide for the excavator. When starting excavation between the preceding elements to construct an excavation hole for the succeeding element, positioning is performed smoothly in the initial stage without causing the so-called escape phenomenon in which the excavator avoids hard concrete. Moreover, by using the wide-spaced part as a guide for the excavator, it is not only possible to hold the excavator in a vertical position and perform stable excavation, but also to ensure accurate cutting and removal of the end face of the preceding element in the pouring direction. It has excellent effects such as making it possible to secure the cutting line.

[Brief explanation of the drawing]

Figures 1 to 7 illustrate one embodiment of the present invention, and Figures 1 to 3, Figure 5 (a), Figure 6, and Figure 7 illustrate construction of underground walls, respectively. A side sectional view explaining the procedure, Fig. 4(a) is a side view of the spacer box, Fig. 4(b)
is a front view of the spacer box, and FIG. 5(b) is a front view of the spacer box.
FIG. FIG. 8 explains another embodiment of the present invention, and is a top view showing a part of the construction pattern of the cylindrical structure I2. 1...Drilling hole for the preceding element, 4...
...Concrete, 5...Spacer box, 6...Preceding element, 6a...
...End face in the direction of pouring, 7...Space, 8...
...Drilling hole for trailing element, 9...Wide interval section, lO...Drilling machine, 11...
... Trailing element, 13 ... Cutting and removal section, W ... Underground continuous wall.

Claims (1)

[Claims] Divide the underground continuous wall to be constructed into a plurality of elements in the construction direction, drill holes for forming the preceding elements at regular intervals in advance, and pour concrete into the excavated holes to form the preceding elements. After forming, the space between these preceding elements is excavated with an excavator, and at the same time, the end face of the preceding element in the pouring direction is cut to a dimension l to excavate a hole for the succeeding element, and concrete is poured into this excavated hole. In the method for constructing a continuous wall by forming a trailing element that is continuous with the leading element, at least the upper end of the cutting end face in the splicing direction of the excavated hole for forming the leading element. A process of pouring concrete with a spacer box having a thickness of l dimension intervening to form a preceding element, and removing the spacer box after the concrete hardens to form a wide spaced part between the preceding elements with a large distance between their end faces. process and 2
A method for constructing an underground continuous wall, comprising the step of excavating between the preceding elements of the body using the widely spaced portion as a guide for the excavator.