JP2607966B2 - Expanded connecting wall construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention particularly relates to a method for constructing a continuous wall in which only one wall surface of a continuous wall is expanded.

[Conventional technology] In general, there is a method of using a continuous wall as a foundation pile that also serves as a mountain retaining when constructing a building. In this method, a portion corresponding to the wall thickness is dug into a groove, and a reinforced concrete wall is formed therein. It is a method of making it continuously.

[Problems to be Solved by the Invention] In the above-described continuous wall method, when the building is high-rise and the weight increases, or when the supporting layer of the land is weak, the wall thickness of the continuous wall is increased. You have to increase your support. In order to increase the wall thickness of the connecting wall, a cross section in which the bottom of the wall is extended on both sides usually forms an inverted T-shaped connecting wall,
It is not permissible for the overhanging overhang to penetrate into the adjacent land, so it is difficult to provide it at a location just below the boundary with the adjacent land. Therefore, in such a case, it is necessary to form an L-shaped expanded connecting wall in which the section protruding only on one side of the bottom portion, but the conventional RCD (reverse circulation drill) method and the like meet the demand. There was a problem that could not be achieved.

The present invention has been made to solve such a conventional problem, and has an object to propose a method of constructing an expanded bottom wall in which an L-shaped cross section can be easily formed. is there.

[Means for Solving the Problem] As means for technically solving this problem, a preceding boring process and a bottom excavation process are included. In the preceding boring process, a groove for a continuous wall is formed to a wall thickness by an excavator. Correspondingly, a predetermined width is excavated to a predetermined depth, and the bottom enlarging excavation step is performed in such a manner that the axis of the drill rod of the enlarging bottom excavator is eccentric to one of the side wall surfaces without being aligned with the center line of the groove. A guide member for holding the position attached to the protection pipe is brought into contact with the other side wall surface to lower the bottom-excavating machine to the bottom of the groove, and the drill rod is rotated by a rotary table installed on the ground, thereby causing the vertical-bottoming machine to move vertically. The gist of the invention is a construction method in which only the one side wall surface is excavated and the bottom is expanded while maintaining the property.

[Operation] With the above-described method, an expanded bottom continuous wall having an L-shaped cross section can be easily formed, and if the side of the wall that does not expand is the boundary side with the adjacent land, the overhanging portion has a supporting force that does not enter the adjacent ground. A large continuous wall can be provided just before the boundary line.

Examples Hereinafter, examples of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a preceding boring process, in which a groove 1 for a continuous wall is used.
Is excavated to a predetermined depth H with a constant width d corresponding to the wall thickness. For this excavation, a rotary excavator and a bucket-type excavator, which are the same as the conventional excavators for connecting walls, can be used.

FIG. 2 shows a bottom excavation process, in which the bottom excavation is performed by a reverse circulation drill method. In this case, the lower excavator 2 is not lowered and the one side wall surface 1a of the groove 1 is lowered.
And lower it. That is, the axis of the drill rod 2a of the bottom excavator 2 is eccentric to the one side wall surface 1a side without being aligned with the center line C of the groove. Reference numeral 3 denotes a guide member for holding the offset of the bottom-bottom excavator 2, which is attached to the protection pipe 4 of the drill rod and abuts on the other side wall surface 1b of the groove 1. The bottom excavator 2 can be easily lowered to the groove bottom via the. The bottom excavation is performed while rotating the drill rod 2a on the rotary table 5, but since the axis of the drill rod 2a is eccentric as described above, the groove 1
Is expanded only toward the side wall surface 1a. When the width d of the groove 1 is 1200 mm, the drill shaft diameter of the deep-bottomed excavator 2 is 800 m.
m, the diameter of the expanded bottom by the expanded bottom excavator 2 is theoretically 1486 mm, so that the expanded width d 'of the side wall surface 1a is obtained.
Is [(1486−800) / 2] = 343 mm, so that the total width D (d + d ′) of the enlarged diameter portion is 1543 mm. Reference numeral 6 denotes a discharge device, which discharges excavated soil and slime which has been made into muddy water by injecting water.

FIG. 3 shows a concrete casting step, in which a reinforcing bar 7 is inserted into the groove 1, and concrete is poured by a tremy tube 8 to form a continuous wall 9. If the side wall surface 1b of the groove 1 that does not expand is directed to the adjacent land side of the land boundary line, the continuous wall 9 formed just above the boundary line without the protrusion due to the expanded floor penetrating into the adjacent land side. The continuous wall 9 having a large supporting force can be formed.

[Effects of the Invention] As described above, according to the present invention, an L-shaped continuous wall whose section is expanded on one side only can be easily formed, so that the bottom can be expanded at a location just near the boundary line of the land. It is possible to form a continuous wall having a large supporting force without the part invading the adjacent land side, and the effect is extremely remarkable.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a groove formed by the preceding connecting wall step of the present invention, FIG. 2 is a cross-sectional view showing a bottom excavation step, and FIG. 3 is a broken cross-sectional view showing a concrete placing step. DESCRIPTION OF SYMBOLS 1 ... Groove, 1a, 1b ... Side wall surface 2 ... Bottom excavator, 2a ... Drill rod 3 ... Guide member 4, ... Protection pipe 5 ... Rotary table 6 ... Ejector, 7 ... Rebar 8 ... Tremy tube, 9 ... wall

Claims (1)

(57) [Claims] The present invention includes a preceding boring step and a bottom excavation step. In the preceding boring step, a groove for a continuous wall is excavated by an excavator to a predetermined width and a predetermined depth corresponding to the wall thickness. The eccentricity of the axis of the drill rod of the bottom-bottom excavator is not aligned with the center line of the groove, but is eccentric to one of the side wall surfaces, and the position holding guide member attached to the protection pipe of the drill rod is attached to the other side wall surface. The drilling machine is brought into contact with the drilling machine, and the drilling machine is lowered to the bottom of the groove. At the same time, the drill rod is rotated by a rotary table installed on the ground, and only one of the side wall surfaces is drilled while the verticality of the drilling machine is maintained. A method of constructing a wide-walled continuous wall, characterized in that: