JP2000178966A - Structure of diaphragm wall - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of a diaphragm wall, in which construction cost is reduced and the term of works is shortened. SOLUTION: In the diaphragm 1 used as the earth retaining of an underground structure, an approximately truncated-shaped bottom expanding section 2 is formed to the lower section of the diaphragm 1 at a specified space. A ditch for the diaphragm is excavated and the bottom expanding section 2 is excavated to the lower section of the excavated ditch by using an excavator, in which a bottom expander is installed at a front end, or a vertical pit containing the bottom expanding section 2 is excavated previously and the ditch is excavated so that the bottom expanding section 2 is formed as a lower section. Slime in the ditch, to which the bottom expanding section 2 is formed, is removed while a cage is disposed and the diaphragm wall is formed by placing concrete. Since floating resistance force to ground water is increased by the bottom expanding section at that time, the wall thickness of the diaphragm can be formed thinly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a structure of an underground continuous wall.

[0002]

2. Description of the Related Art An underground continuous wall is used as a kind of retaining wall of an underground structure. Generally, a portion corresponding to the underground wall of the surrounding soil is formed by using a stabilizing liquid in accordance with the wall thickness. It is formed by digging into a mold, arranging a reinforced cage therein, and casting concrete to form a reinforced concrete wall continuously. This underground continuous wall is frequently used because recent urban facilities such as underground structures, underground shopping malls, and underground parking lots often use the underground.
The scale can be as large as 40 m. Also, LN
G (liquefied natural gas) is also used as a water stop wall for underground tanks, and construction examples with a depth of about 100 m underground have already appeared.

[0003]

FIG. 5 shows an underground continuous wall A
Shows an example constructed as a water blocking wall of the underground tank B. In this case, the underground continuous wall A formed in a cylindrical shape is used as a retaining wall when the underground tank B is constructed. Further, the weight of the underground continuous wall A prevents the underground tank B from being lifted by the groundwater when the underground tank B is completed. However, the wall thickness D of the underground continuous wall A is greater than the thickness required for strength in order to prevent lifting. It is extremely uneconomical to increase the wall thickness D of the underground continuous wall A more than necessary, not only increasing the construction cost but also prolonging the construction period. The present invention has been made to solve such a conventional problem,
It is an object of the present invention to provide an underground continuous wall structure capable of reducing the construction cost and shortening the construction period.

[0004]

As a means for achieving this object, the present invention relates to an underground continuous wall used as a mountain retaining structure for an underground structure, wherein a predetermined interval is provided below the underground continuous wall. The gist is a structure in which an expanded bottom is provided. Thereby, for example, the resistance of the water stop wall to the rising of the underground tank is increased, and the thickness of the wall can be reduced, so that the construction cost can be reduced and the construction period can be shortened.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a water blocking wall of an underground tank will be described below in detail with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes an underground continuous wall, which is formed in the ground in a cylindrical shape by a known construction method. In this case, the wall thickness d is formed to be smaller than the wall thickness D of the conventional underground continuous wall A shown in FIG. 5 (d <D), and a substantially conical shape is formed at a lower portion of the wall at predetermined intervals as shown in FIG. A trapezoidal expanded bottom 2 is provided. This expanded bottom 2 is preferably provided at the lower end of the underground continuous wall 1 as much as possible.

For example, as shown in FIG. 3 (a), after excavating an excavation groove 3 for an underground continuous wall, the excavation section 2 is excavated using an excavator 5 equipped with an excavation machine 4 at the tip. Is formed. The bottom expanding machine 4 has cutting blades 4a and 4b which can be opened and closed as shown in FIG.
As shown in FIG. 4A, it is inserted from above into the excavation groove 3 in a closed state, and as shown in FIG. 4B, the cutting blades 4a and 4b are opened to perform excavation by rotating the shaft. Cutting blade 4
a, 4b are closed and pulled up.

[0007] As for the construction order, as described above, the excavation groove 3 is excavated first, and then the expanded portion 2 is excavated, or the excavator 5 excavates the vertical hole including the expanded portion 2 first. Thereafter, the excavation trench 3 may be excavated, and it is possible to arbitrarily select a suitable one for the site. Thereafter, the slime in the excavation trench 3 is removed, and the underground continuous wall 1 is formed by laying a reinforcing cage 6 and casting concrete 7 as shown in FIG.

The underground continuous wall 1 thus formed
Is provided with a plurality of the widened bottom portions 2 at regular intervals along a lower circumferential direction. Since the earth and sand 9 above the expanded bottom portion 2 can contribute to the lifting resistance, the wall thickness d may be set so as to satisfy the strength required as a waterproof wall. It can be thinner than D. In the above embodiment, the water blocking wall for the underground tank has been described, but the present invention can be widely applied as an underground continuous wall of an underground structure. Further, the shape of the expanded bottom is not limited to a substantially truncated cone.

[0009]

As described above, according to the present invention, the rising resistance is increased by providing the expanded bottom portion under the underground continuous wall, and the thickness of the wall can be reduced, so that the material cost is reduced. In addition, since a small excavator or the like can be used, the cost can be reduced, and the construction cost can be reduced. Further, although the excavation work of the expanded bottom portion is added, the total excavation amount is reduced and the slime is easily removed, so that an excellent effect such as shortening of the construction period is achieved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an underground continuous wall according to the present invention.

FIG. 2 is a schematic sectional view taken along line XX in FIG.

FIG. 3 is an explanatory view showing an example of forming a widened bottom portion, in which (a) shows a state at the time of excavation of the widened portion, and (b) shows a state at the time of placing concrete.

FIG. 4 is an explanatory view showing an example of a bottom expanding machine, in which (a) shows a state when the cutting blade is closed, and (b) shows a state when the cutting blade is opened.

FIG. 5 is a schematic sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Underground continuous wall 2 ... Expansion part 3 ... Excavation groove 4 ... Excavation machine 5 ... Excavator 6 ... Reinforcing basket 7 ... Concrete 8 ... Underground tank 9 ... Sand

Claims (1)

[Claims] 1. An underground continuous wall structure comprising: an underground continuous wall used as a mountain retaining of an underground structure, wherein an expanded bottom portion is provided at a predetermined interval below the underground continuous wall.