JPH0473489B2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention involves excavating a continuous trench-like hole in the ground,
A continuous reinforced concrete wall was built inside this,
Concerning underground continuous wall construction methods for constructing earth retaining walls, water-stop walls, underground structure walls, etc.

《Prior art》 For underground continuous walls, there are the interlocking pipe method and the cutting joint method as methods for connecting the following panel to the preceding panel.

The former interlocking pipe method involves inserting locking pipes at both ends of the preceding panel section.
Excavating the section partitioned by the rocking pipe,
This construction method involves pouring concrete and constructing the preceding panels, then pulling out the locking pipe, excavating the trailing section, and constructing the trailing panels.

In the latter cutting joint construction method, the preceding work section is excavated in the shape of a rectangular parallelepiped, concrete is poured, and the preceding panel is constructed, and then the subsequent work section is excavated, and the exposed end of the preceding panel is cut using a hydro cutter. This is a construction method in which the concrete is cut to remove weak parts such as defective concrete at the joint, and then concrete is poured to join the succeeding panels.

Other methods include wrapping the horizontal reinforcing bars using special joints, or using PC jointers, I-type steel jointers, etc. All of these have been established as different construction methods in that the joining methods between the leading panel and the trailing panel, that is, the elements, are different. In addition, various efforts have been made to facilitate the implementation and construction of the joining means and to improve the bonding strength between the leading panel and the trailing panel.

<<Problems to be solved by the invention>> However, in any construction method, water may leak from the joints between elements, and there are also difficulties such as slime getting around during construction. Various efforts have been made.

The present invention has been made in view of the above circumstances, and its purpose is to provide a simple underground wall construction method that can strengthen the bond between elements and obtain a water-stopping effect.

《Means for solving the problem》 The process of erecting reinforcing bars in a trench drilled underground and then pouring concrete to form a wall is repeated, and the walls thus formed are successively laid horizontally. In the underground continuous wall construction method, which connects and connects the wall in the same direction, the wall expands in volume during the curing process and hardens as it is in order to press and connect the wall to the joint of the adjacent wall. It is characterized by being formed using expanded concrete.

<<Operation>> The expansion element is obtained using an expansion cement mixed with an expansion agent. This expansive cement is made by mixing calcium sulfoaluminate (3CaO・Al ₂ O ₃・CaSO ₄ ) with Portland cement, or by firing and pulverizing Portland clinker containing calcium sulfoaluminate, and when mixed with water. The hydration reaction produces ettringite or calcium hydroxide, which acts as an expansion source and causes the concrete to expand after setting.

The walls themselves, which are constructed with reinforcing bars and serve as structural members, are made of expanded concrete, and the expansion action of the walls made of expanded concrete causes compression in adjacent elements, and the expanded concrete A prestress is also applied to the element itself, which ensures a degree of adhesion that sufficiently absorbs free contraction after initial expansion. This free expansion strain is approximately 500×10 ⁻⁶ (m).

Therefore, if the panel width is 5 (m), the amount of elongation Δ is Δ = 5 × 500 × 10 ^-6 = 2.5 (mm). The joints are tightly pressed together with sufficient pressing force by the expanded concrete forming the panel itself, and it is possible to prevent gaps from forming between them in the first place.

<<Example>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIGS. 1a and 1b are plan views of an underground wall formed by the method of the present application, in which each element 1 is continuously connected and joined in the longitudinal direction, and constitutes an underground continuous wall 2. . Each element 1 may be constructed by alternately connecting elements 1 made of ordinary concrete and elements 1' made of expanded concrete, or may be composed only of elements 1'.

This will be explained in more detail below in FIG.

In this example, concrete is placed in vertical holes that are intermittently excavated, leaving an intermediate ground, thereby intermittently constructing leading walls, and excavating the intermediate ground between the constructed leading walls. At this time, the end face of the leading wall is cut and excavated to expose the roughened joint surface, and concrete is poured into this intermediate hole to connect the trailing wall to the leading wall. This is a method of construction.

First, in Fig. 2, the leading wall 3 constituting one element of the underground continuous wall is made of ordinary concrete reinforced with steel bars in a deep vertical hole 5 that is intermittently excavated, leaving an intermediate ground 4. It was constructed intermittently by pouring concrete into the concrete.

A groove 6 is set in the center of the end joining portion of the leading wall 3 that contacts the trailing wall along the vertical direction.

Next, an excavated vertical hole is formed in the intermediate ground 4, as shown in FIG. During this excavation, in the stabilizing liquid 7 filled in the vertical hole, the end face of the joint part of the leading wall 1 and the part of the groove 6 are roughened by a cutting means such as a drum-type cutter. Cut. As a result, an uneven surface 8 is formed at the joining portion of the leading wall 3, and a mortise hole 9 having an uneven surface 8 is formed in the longitudinal direction at the position of the groove 6.

Next, as shown in Figure 4, inside the middle vertical hole,
By pouring expanded concrete reinforced with reinforcing bars, the joint between the ordinary concrete leading wall 3 and the expanding concrete trailing wall 10 is formed by an uneven surface 8 and a mortise 9 with the entire joint surface roughened. A joint structure will be formed and jointed together.

<<Effects>> As explained in detail above, according to the construction method of the present invention, the wall itself, in which reinforcing bars are erected and is formed as a structural member, is formed using expanded concrete. Just by expanding the volume of the panels, the joining parts of the panels are brought into strong pressure contact, making it possible to connect the walls to each other without using shear connectors or reinforcing steel materials at the joining parts, and also to reduce gaps in the joining parts. It is also possible to prevent the occurrence of In addition, prestress can be applied between the panels by the press-fitting action at the joints between the panels. Therefore, the gap between the panel joints is extremely small, and it is possible to obtain an underground continuous wall with a significantly improved water-stopping effect without having to fill it with a special sealant or the like.

[Brief explanation of the drawing]

Fig. 1 is a plan view for explaining the embodiment, Fig. 2 is a plan view for explaining the embodiment;
Figures 4 through 4 are plan views illustrating the construction order of the construction method of the present invention. 1... Ordinary concrete element, 1'...
Expandable concrete element, 2... Underground continuous wall, 3... Leading wall, 4... Intermediate ground, 5... Vertical hole, 6... Groove, 7... Stabilizing liquid, 8... Uneven surface, 9
...Mortise, 10... Trailing wall.

Claims (1)

[Claims] 1 The process of placing reinforcing bars in a trench dug underground and then pouring concrete to form a wall is repeated, and these formed walls are sequentially poured laterally to form a connection. In the underground continuous wall construction method, the wall is formed using expansive concrete that expands in volume during the curing process and hardens as it is, in order to press and connect the wall to the joint of the adjacent wall. An underground continuous wall construction method that is characterized by the following.