JPS59109615A - Construction work of continuous underground sheathing wall - Google Patents

Abstract

PURPOSE:To reduce the cost of the construction work of a continuous underground sheathing wall as well as shorten the period of the construction work by a method in which an iron bar cage attached with a twisted PC wire-inserted sheath is inserted into a trench, concrete is placed, and then a prestress is introduced into the twisted PC wire. CONSTITUTION:An iron bar cage 1 attached with a twisted PC wire-inserted sheath 3 is hung down into a wall strench, and concrete 5 is placed. After the strength of the concrete develops, primary excavation 10 is made and the first step strut 6 is laid. A tension is applied to the twisted PC wire 2 by a jack 7 attached to the upper end of the twisted PC wire 2, and a cement-based grout is injected into the sheath 3. After the strength of the grout develops, the twisted PC wire 2 is fixed and a prestress is introduced against a moment by the side pressures entailed at the time of excavation into the on-site reinforced concrete wall 8 for a continuos underground wall.

Description

[Detailed Description of the Invention] This invention is a new continuous underground wall that increases the contralateral pressure bending strength, reduces deformation due to lateral pressure, and reduces the number of required struts to reduce costs and shorten the construction period. Involved in providing construction methods for mountain clay walls.

Conventionally, continuous underground walls and earthen walls are bent toward the root cutting side (ventral side) due to the lateral pressure of the ground layer (back side) when root cutting is performed, so this is done by using struts over a predetermined number of steps. Support is being provided.

However, as the number of struts increases, the cost and construction period increase, and the length of the working space formed between the struts also becomes narrower, which is inconvenient.

The present invention was made in view of the above circumstances, and its gist is that P
The lower end of the sheath into which the C steel wire has been inserted is fixed to the dorsal reinforcing bars with fixing hardware, and the dorsal part is meandered between the dorsal and ventral reinforcing bars, bypassing the joint part of the cut beam, and finally The upper end of the sheath is fixed to the dorsal reinforcing bars, this reinforcing cage is inserted into the excavation groove, concrete is poured, and after waiting for strength to develop, tension is applied to the POm wire to prestress it. By introducing this system, it is possible to give the reinforced concrete walls of continuous underground walls and earthen walls the bending strength to resist the lateral pressure during root cutting, thereby reducing the number of required beam steps, reducing costs and shortening the construction period. This is the point I was aiming for.

This will be explained in detail below based on the drawings.

That is, FIG. 1 is a detailed vertical sectional view of a reinforcing bar cage 1 in an underground continuous wall according to the present invention, and as shown in the figure, the PO strands 2
The sheath 3 into which the PG strands have been inserted is installed in a meandering manner to the reinforcing bar cage 1, and the lower end of the PG stranded wire 2 is fitted with a fixing metal fitting 4 that acts as a reaction force when prestress is introduced, and the underground continuity near the virtual fulcrum during root cutting is installed. It is fixed to the reinforcing bar 1a on the back side of the wall, and the back and ventral reinforcing bars are meandered so as to bypass the sill joint part, and the upper end of the other side is inserted into the sheath during concrete pouring. After applying a seal to prevent concrete slag from entering, it is made longer than the top of the concrete pouring and fixed to the reinforcing bar 1a on the back side of the underground continuous wall.

The example shown in Fig. 1 shows the case of only the first stage strut,
This is a case where there is no detour on the way.

The middle part 3a of the sheath 3 is fixed to the ventral reinforcing bar 1b of the underground continuous wall while maintaining a smooth curve.

Figure 2 shows how to construct a continuous underground wall using the reinforcing bar cage 1 manufactured according to the above procedure.

However, this figure shows the case of two-stage strut construction with one detour in the middle.

That is, the reinforcing bar cage 1 is suspended into a wall groove, and concrete 5 is poured.

Waiting for concrete 50 strength to develop, primary excavation lO is carried out, and the first stage strut 6 is erected.

The first stage strut 6 may be constructed in advance and used together with the first floor floor.

Next, the oil jack 7 attached to the upper end of the PC stranded wire 2
This applies tension to the PO stranded wire 2, and in this state, cement-based grout is injected into the tube of the sheath 3.

Waiting for the strength of the cement grout material to develop, the fixing work of the PO strands 2 is carried out, and a prestress is introduced into the cast-in-place reinforced concrete wall 8 of the continuous underground wall to counteract the moment due to the lateral pressure at the time of root cutting.

Prestressing shall be done using the boss tension method.

After that, secondary excavation, erection of two-stage strut 9, final excavation 10'
Do this.

As described above, according to the present invention, the continuous underground wall cast-in-place reinforced concrete wall 8 can increase the opposite side compression bending strength between the supporting points such as the struts 6.9 and the joint parts, so that the required The number of struts can be reduced, reducing costs and shortening the construction period. Furthermore, the length between the upper and lower struts can be increased, which is suitable for work.

[Brief explanation of the drawing]

FIG. 1 is a detailed diagram of a reinforcing bar cage in an underground continuous wall in the case of only a first-stage strut, and FIG. 2 is a detailed explanatory diagram of the present invention in the case of a two-stage strut. 1... Rebar cage 2... PO stranded wire 3-sheath
7...Inventor of oil jatsugi 1)
Jun Ro Applicant: Takenaka Corporation N? z layer

Claims (1)

[Claims] The lower end of the sheath into which prestressed steel wire was inserted during the fabrication of a reinforcing bar cage for a continuous underground wall was fixed to the back reinforcing bar with a fixing hardware, and the back and ventral reinforcing bars bypassed the joint part of the strut midway. Finally, the upper end of the sheath is fixed to the dorsal reinforcing bars, and this reinforcing cage is inserted into the excavated groove and concrete is poured to develop strength.
By applying tension to the C steel wire and introducing prestress, the reinforced concrete wall of the continuous basement wall and earthen wall is given bending strength to resist the lateral pressure at the time of root cutting, thereby reducing the required number of struts. A method for constructing continuous underground walls and earthen walls, which is characterized by being able to reduce.