JPH03115656A - Compaction method for concrete structure - Google Patents

Abstract

PURPOSE:To homogenize the unit strength of a concrete structure by vertically pressurizing the top end of the concrete structure in which concrete placing is completed up to the top end by a plate or the like to dehydrate the upper layer followed by compaction. CONSTITUTION:In compaction method using a jack, a plate 1 corresponding to the thickness or sectional width of a concrete structure S such as a pile prepared in field is placed on the top end of the concrete C of the concrete structure S. A frame 3 is laid between anchors 2, 2, buried on both sides of the structure S, and a jack 4 is placed between the plate 1 and the frame 3. Then, the rod 4a of the jack 4 is extended to closely press the upper layer part of the structure S with the plate 1. The magnitude of the pressurizing force is about 20-50 t/m<2>. Hence, the vertical heterogeneous state of the concrete structure S can be solved to homogenize the unit strength.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for compacting concrete structures, such as underground continuous walls and on-site piles, to homogenize them in the vertical direction.

(Problem to be solved by the invention) For example, in underground continuous walls and on-site constructed piles constructed using the muddy water displacement method, concrete is poured into an excavated hole through a tremie pipe, and then the concrete compacts naturally under its own weight. However, since the weight of concrete applied from above differs depending on the depth, the degree of compaction differs in the depth direction.

In other words, sufficient compaction and dewatering can be expected in the lower layer, where the overload is large, but this effect mainly remains in the lower layer, and the loading effect weakens as you move toward the upper layer, so the compressive strength of the completed concrete structure is It becomes heterogeneous in the direction.

This invention was made by paying attention to the problems faced by cast-in-place concrete structures, and aims to propose a method for eliminating vertical non-uniformity and improving quality.

(Means for Solving the Problems) In the present invention, a load is applied vertically downward from the top surface of the concrete structure, covering almost the entire surface of the top surface of the concrete structure for which concrete has been poured up to the top. Applying the same loading effect to the upper layer as the lower layer, forcibly consolidating the upper layer of the concrete structure before it hardens, and at the same time dewatering that area to homogenize the concrete structure vertically and compressing it. Increase strength.

(Example) The present invention will be explained below based on the drawings showing one embodiment.

As shown in Fig. 1, this invention applies vertically downward force from the top of the concrete c that has been completely placed in a concrete structure S such as an underground continuous wall or on-site pile to consolidate the concrete C in the vertical direction. At the same time, this method improves the quality of the concrete structure S by dewatering it.

Is the amount of applied force 20 to 50t/n? The degree is a guideline;
As shown in FIG. 1, this load is applied evenly over almost the entire surface of the concrete structure S immediately after the concrete C is placed and before the concrete C hardens.

Further, in order to encourage the discharge of water floating from the consolidated concrete C from around the loading surface and to improve the consolidation effect, it is preferable to make the loading area slightly smaller than the cross section of the concrete structure S, as shown in the figure.

A specific method of the present invention will be explained with reference to the following drawings in FIG. 2 showing a case where the concrete structure S is a continuous wall.

In the embodiment shown in Fig. 2-■, a plate 1 of an appropriate length having a width corresponding to the thickness or cross section of the concrete structure S is placed on the top of the concrete structure S. A frame 3 is erected between the anchors 2 and 2 buried in the ground, a jack 4 is installed between the frame 3 and the plate 1, and the rond 4a of the jack 4 is extended while taking the reaction force with the anchors 2, 2. In this method, the plate 1 is pushed down and loaded.

Figure 2-■ shows the case where the reinforcing bars placed in the concrete c are exposed from the top, but the jack 4 is the plate l.
The plate 1 is installed between the insertion holes 1a drilled in the plate 1 for insertion of reinforcing bars, and a force is applied to the plate 1 in the manner described above.

In this case, in addition to draining water from around the plate 1,
This has the advantage of promoting dehydration from a.

The embodiment of FIG. 3 is similar to the embodiment of FIG.
An airbag 6 is installed between the top and the restraining plate 5, which is fixed on the top of the concrete C according to 2 and has an area similar to that of the plate 1, and air is pumped into the top of the concrete C to inflate it. This is a loading method that applies a load to the end face.

Consolidation of the concrete C is performed by the loading method shown in FIG. 2 or FIG. 3 above.

In the embodiment shown in FIG. 4, holes 1b are drilled over the entire surface of the plate 1, and when force is applied from above by the method using the jack 4 or the air bag 6 shown in FIG. This is a method to improve the dehydration effect from water.

The embodiment shown in FIG. 5 is a method of promoting dehydration by attaching a water repellent material 7 such as a non-woven fabric to the back side of the plate 1 and allowing water that has floated to the top to escape to the periphery of the plate 1 and circulate around it.

The embodiment shown in FIG. 6 is a method in which a concrete c sea urchin pie break 8 is inserted during loading and vibration is applied to the concrete c, thereby increasing the effect of compaction and dewatering of the concrete c.

(Effects of the Invention) This invention is as described above, and after concrete is poured and before it hardens, a load is applied evenly over the entire surface from the top, and the upper layer, which cannot be consolidated by its own weight alone, is forcibly Since the concrete is consolidated and dehydrated, the strength of the concrete structure is made uniform in the depth direction, and its quality can be improved.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the gist of the present invention, Figure 2-1, ■
3 is a perspective view showing a method using a jack, FIG. 3 is a perspective view showing a method using an air bag, and FIGS. 4 to 6 are perspective views showing other embodiments. S...Concrete structure, C...Concrete, b...Reinforcement, ■...Plate, 1a...Through hole, 1b. ...hole,
2...Anchor 3...Frame, 4
・・・・・・Jyatsuki, 4a・・・mouth・do, 5
...Restraint plate, 6... Air bar ng, 7
...Water repellent material, 8...Pie break. Figure 3 Figure 3 Figure 3

Claims (1)

[Claims] (1) A load is applied vertically downward over almost the entire surface of the top surface of the concrete structure for which concrete has been poured up to the top, to consolidate the upper layer of the concrete structure before it hardens, and to A compaction method for concrete structures that dewaters.