JPH04269210A - Construction method for underground continuous wall - Google Patents

Abstract

PURPOSE:To prevent the collapse of a groove wall by providing an excavation groove in a columnar continuous wall, arranging reinforcing bars in the excavation groove, and filling concrete in the excavation groove. CONSTITUTION:Many mortar piles 6 are continuously provided in line to form a nearly circular column continuous wall 7. A guide wall 8 is formed at the upper section of the continuous wall 7. The continuous wall 7 is excavated with an underground continuous excavator 9 while it is guided by the guide wall 8, and an excavation groove 10 is formed with only a surface layer section 7a left. A reinforcing bar cage is arranged in the excavation groove 10, then concrete is placed and hardened to form an underground continuous wall 3.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for constructing an underground continuous wall,
In particular, the present invention relates to a method of constructing a continuous underground wall that is suitable for use when installing a continuous underground wall in the ground where the upper layer is a soft soil layer and the deeper layer is hard rock.

0002

[Prior Art] Since it is difficult for general-purpose underground continuous wall excavators that have been widely used in the past to excavate into hard rock, it is difficult to excavate into hard rock, so as mentioned above, it is difficult to excavate into hard rock. When creating a continuous wall, the hole is filled with a stabilizing liquid to protect the hole wall, and an all-casing excavator is used to excavate in a row of columns into hard rock, and a reinforcing bar cage is installed inside the excavation trench. It is common to directly form a continuous reinforced concrete wall by arranging walls and pouring concrete.

0003

[Problem to be solved by the invention] However, in that case,
When placing a reinforcing bar cage in an excavated trench, the trench wall is opened, so it is difficult to install the trench in a soft soil layer where the stability of the trench wall cannot be maintained with only the stabilizing liquid filled in the trench. Some kind of measure was needed to prevent the wall from collapsing, and it was desired to provide an effective means for that purpose.

0004

[Means for Solving the Problems] The present invention has been made in view of the above circumstances, and when installing an underground continuous wall,
First, an unreinforced columnar continuous wall with a wall thickness greater than that of the underground continuous wall is formed using a cast-in-place method using poor mix mortar, and the interior of the columnar continuous wall is excavated, leaving only the surface layer. This method is characterized by creating an excavated trench, placing reinforcing bars in the trench, and filling it with concrete to provide an underground continuous wall.

[0005]

[Operation] At the location where the underground continuous wall is to be formed, we first form a weak temporary column continuous wall made of poorly mixed mortar, and then excavate a trench formed inside the column leaving the surface layer of the column continuous wall. By finally forming a strong underground continuous wall made of reinforced concrete, the inner surface of the excavated trench is protected by the surface layer of the column continuous wall that was left unexcavated, which prevents the trench wall from collapsing. Such things are prevented.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The construction method of the example shown below is based on the construction of a shield shaft (starting shaft or arrival shaft) 2 on the ground 1 where the upper part is a soft soil layer and the deeper part is hard rock. The underground continuous wall 3 as a retaining wall is provided so as to have a substantially circular shape in plan view.

[0007] In this case, first, a temporary column continuous wall is installed at the location where the underground continuous wall 3 is to be formed by a cast-in-place method. That is, as shown in FIG. 1(a), a mortar pile 6 is provided by forming an excavation hole reaching hard rock using an all-casing excavator 5 and replacing the inside with mortar. By continuously forming a large number of piles 6 in a row, a substantially circular column continuous wall 7 as shown in FIG. 1(b) is provided. The column continuous wall 7
The wall thickness is made larger than the wall thickness of the underground continuous wall 3 to be formed. In addition, the column continuous wall 7 needs to be weak so that it can be easily excavated in the subsequent process, so no reinforcing bars are used at all, and the mortar filled in the excavation hole has a strength qu= 5~10Kgf/c
A poorly mixed mortar of about m2 will be used.

Next, as shown in FIG. 2, a guide wall 8 is formed on the upper part of the columnar continuous wall 7 formed above, and then, while being guided by the guide wall 8, as shown in FIG. The column continuous wall 7 is excavated using the underground continuous wall excavator 9, and the surface layer parts 7a, 7a of the column continuous wall 7 are excavated.
Excavation grooves 10 are formed inside, leaving only the holes. At this time, as mentioned above, since the columnar continuous wall 7 is unreinforced and made of poorly mixed mortar, a general purpose machine such as a bucket type can be used as the underground continuous wall excavator 9. , the excavation trench 10 can be easily formed using such an underground continuous wall excavator 9.

After forming the excavated groove 10 to a predetermined depth inside the column continuous wall 7 as described above, the excavated groove 1
A reinforcing cage (not shown) is placed inside the container, and then concrete is poured. When the poured concrete hardens, a strong underground continuous wall 3 made of reinforced concrete is completed as shown in FIG. 4, and the inside of the wall 3 is excavated to complete the shaft 2. Note that the surface layer 7a of the columnar continuous wall 7 remaining on the inner surface side of the formed underground continuous wall 3 can be easily removed when excavating the shaft 2, so that the inner surface of the underground continuous wall 3 can be made flat. It can be done.

According to the above method, the inner surface of the excavated trench 10 is protected by the surface layer 7a of the column continuous wall 7 that remains unexcavated, so even if the ground is a soft soil layer, the trench wall will not collapse. It is possible to reliably prevent this. In addition, it is possible to excavate the columnar continuous wall 7 made of deep hard rock and poorly mixed mortar only by using the general-purpose all-casing excavator 5 or the underground continuous wall excavator 9. Therefore, special excavation is possible. It does not require any machinery and is advantageous in terms of labor costs.

[0011] The present invention can be widely adopted not only when constructing an underground continuous wall as a retaining wall for a shaft as described above, but also when constructing a general underground continuous wall. Needless to say.

0012

[Effects of the Invention] As explained above, the present invention provides the following advantages: After forming a weak columnar continuous wall made of poorly mixed mortar,
We excavated the inside of the column continuous wall, leaving the surface layer intact, and formed a strong underground continuous wall made of reinforced concrete within the excavation groove. The inner surface of the excavated trench is protected by the surface layer, making it possible to reliably prevent the trench wall from collapsing.In addition, it is possible to reliably prevent the collapse of the trench wall. It is possible to excavate it, and therefore, it is suitable for use when providing an underground continuous wall in the ground where the upper layer is a soft soil layer and the deeper layer is hard rock.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the procedure of an embodiment of the method of the present invention, of which (a) is an elevation view showing a column continuous wall being constructed; FIG. 3 is a plan view of a column continuous wall.

FIG. 2 is a diagram for explaining the procedure of an embodiment of the method of the present invention, of which (a) is an elevation view showing a state in which a guide wall has been constructed, and (b) is a plan view thereof. .

FIG. 3 is a diagram for explaining the procedure of an embodiment of the method of the present invention, and is an elevational view showing a state in which excavated grooves are formed in a column continuous wall.

FIG. 4 is a diagram for explaining the procedure of an embodiment of the method of the present invention, of which (a) is an elevation view showing a state in which an underground continuous wall is formed inside a columnar continuous wall; (b) is a plan view thereof.

FIG. 5 is an elevational view of a shield shaft whose retaining wall is an underground continuous wall constructed by the method of the present invention.

FIG. 6 is a plan view of a shield shaft whose retaining wall is an underground continuous wall constructed by the method of the present invention.

[Explanation of symbols]

1. Ground 3 Underground continuous wall 5 All casing excavator 6 Mortar pile 7 Column continuous wall 7a Surface layer of column continuous wall 8 Guide wall 9 Underground continuous wall excavator 10. Excavation trench.

Claims (1)

[Claims] Claim 1: When installing an underground continuous wall, first, an unreinforced column-row continuous wall with a wall thickness greater than that of the underground continuous wall is formed using a cast-in-place method using poor mix mortar, and the column row continuous wall is An underground continuous wall characterized by creating an excavated trench by excavating the inside of the wall leaving only the surface layer, and placing reinforcing bars in the excavated trench and filling it with concrete to provide an underground continuous wall. Construction method.