JPS61282519A - Horizontal joint placement work of underwater concrete - Google Patents

Abstract

PURPOSE:To strongly form horizontal joints of concrete by a method in which when placed concrete is unhardened, many joint binders are spread and buried, and after the concrete is hardened, the next concrete is driven. CONSTITUTION:Concrete 3 for the first layer is driven on the bottom ground under water. When the concrete 3 is unhardened, many joint binders 4 of a block form are spread unformly from water surface 6 in a cassson 1 and the lower half portions of the binders 4 are buried into the surface layer of the concrete 3. After the concrete 3 is hardened, concrete 5 for the second layer is placed on the concrete 3 and the joint binders 4. The shearing strength of the joint portions of the concretes 3 and 5 can thus be greatly increased by the keying effect of the joint binders 4.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a horizontal pour joint construction method that can firmly construct horizontal pour joints in underwater concrete.

[Prior art]

Conventionally, the horizontal pour joint construction method for underwater concrete is as follows:
(1) A diving worker or a hammering device is moved along the surface of the first layer of concrete poured on the underwater ground to roughen the surface of the concrete, that is, to form a rough surface. (2) burying the reinforcing bars assembled in advance in the first layer of concrete, and then placing the reinforcing bars on top of the first layer of concrete; protrude from the surface of the
A method for placing a second layer of concrete on top of the first layer of concrete. (3) Before the first layer of concrete hardens, a diver uses a high-pressure water jet device along the surface of the first layer of concrete. There is a known method in which a rough surface is formed by moving the concrete and spraying high-pressure water onto the surface of the concrete, and then pouring a second layer of concrete on top of the first layer of concrete. There is.

However, in the case of the above-mentioned method, there are problems with the safety of one worker and poor work efficiency as it requires diving work, and furthermore, the surface of the first layer of concrete is sloped and uneven. There is.

In the case of methods (1) and (3) above, there is no need to move the removal equipment or high-pressure water injection equipment, and in the case of method (2) above, it is difficult to move the surface of the first layer of concrete. The height of the reinforcing bars is set thick in consideration of the slope and slope, but it is uneconomical and complicated because it is necessary to partially change the height of the reinforcing bars.

In addition, in the case of method 11 mentioned above, slime accumulates on the surface of the first layer of concrete when roughening treatment is performed, so it is necessary to remove the slime, but the slime removal work is complicated, and When the water is deep, roughening and slime removal work is difficult.

In the case of method (2) above, it is uneconomical because it requires a large amount of reinforcing bars, and it also requires complicated reinforcing bar assembly work.Furthermore, when it is applied to connecting large areas in deep water, the construction efficiency decreases. The problem is that it is extremely bad.

In addition, in the case of method (3) above, if high aqua regia is injected onto the surface of concrete before hardening, there is a risk that the coarse aggregate will loosen and the pour joint surface will become weakened.

[Purpose and structure of the invention]

The purpose of this invention is to provide a method for constructing horizontal pour joints for underwater concrete that can advantageously solve the above-mentioned problems. 3 is poured, and when the first layer of concrete 6 is in an uncured state, a large number of pouring seam binding materials 4 are sprinkled, and the lower half of the pouring seam binding material 4 is poured into the first layer of concrete 6.
After the first layer of concrete 6 has hardened, a second layer of concrete 5 is placed on top of the first layer of concrete and the joint bonding material 4.
This is a method of horizontally pouring joints for underwater concrete→→→, which is characterized by pouring .

〔Example〕

Next, the present invention will be explained in detail using illustrated examples.

The drawing shows an example of pouring concrete for the underwater bottom of a large caisson in multiple layers; A large caisson 1 is sunk until the lower part of the caisson 1 reaches a predetermined depth in the water bottom ground 2, and the upper end of the caisson 1 is made to protrude from the water surface 6.

Then, the ground inside the caisson 1 is excavated to form a flat excavation surface 7.

Next, as shown in FIG. 3, a working scaffolding frame 8 is installed on the underwater ground 2 near the caisson 1, a concrete pump 9 is placed on the working scaffolding frame 8, and the discharge port of the concrete pump 9 is placed on the working scaffolding frame 8. The tremie pipe 11 connected via the hose 10 is placed inside the caisson 1 and moved to the crane 12.
The first layer of concrete 3 is placed on the excavated surface 7 in the caisson 1 under water.

After the first layer of concrete 3 has been poured, while the concrete 6 is still in an uncured state, a large number of lumps of coarse aggregate or relatively small concrete blocks, etc., are poured as shown in Figure 4. Spread the seam binding material 4 evenly from above the water surface B in the caisson 1, and embed the lower half (approximately half) of the seam binding material 4 into the surface side of the first layer of concrete 3. let Note that the seam binding material 4 may be sprayed from a predetermined height underwater.

Next, after the first layer of concrete 3 has hardened and the pour joint binding material 4 has been firmly fixed to the concrete 3,
As shown in FIG. 5, the tremie pipe 11 is placed inside the caisson 1 again, suspended and supported by the crane 12, and a second
Layer concrete 5 is poured.

When the second layer of concrete 5 is poured on top of the first layer of concrete 6 in this way, those concrete IJ-)
Sufficient shear strength is ensured at the joint by the key effect of the large number of joint binding materials 4 interposed between the joints 3 and 5.

Next, an example of a method of dispersing the seam binding material 4 and a method of determining the time of dispersion when carrying out the present invention will be described.

First, the amount of seam bonding material per unit area of the seam joint is determined in advance, a certain amount of seam bonding material is transported to a predetermined position above the water surface using a clam socket, and then a certain amount of head is Spray the joint binder onto the uncured concrete in the water. In this way, the joint binders, which have a uniform weight of 1 and a specific gravity of 9, fall through the water at a constant speed and penetrate into the uncured concrete to a substantially constant depth.

Furthermore, since the timing of spraying the joint binding material varies depending on the composition of the concrete to be poured, it is necessary to determine the timing of spraying the joint binding material in advance. Next, an example of the determination method will be explained.

First, concrete of the same mix as the concrete that will be poured on the underwater ground is poured into the bottoms of two containers containing water.
Perform the following measurements at each elapsed time.

(1) Spread the seam binding material into the water in one container and measure the penetration depth at that time. At this time, either the head is made equal to that during actual construction, or the speed at which the concrete sinks to the bottom is made equal to the speed at which the joint bonding material sinks to the bottom calculated during construction.

(2) For the concrete in the other container, conduct a known broctor penetration test.

From the measured values in (1) and (2) above, it is possible to know the amount of penetration of the seam bonding material relative to the Zolofter penetration resistance value.

Therefore, during construction, the concrete to be poured is collected in a container, the Zolofter penetration resistance value is measured at appropriate times, and the timing of spraying the joint bonding material to obtain a predetermined penetration depth is determined.

Incidentally, of the measurement methods (1) and (2) above, only one of - may be performed to determine the timing of spraying the seam binding material.

The above embodiments demonstrate that the present invention can be applied to the first layer of concrete 6 and the second layer of concrete.
Although this is an example in which the present invention is applied to a joint between concrete layers 5 and 5, the present invention can be similarly applied to a joint between three or more layers of concrete. Furthermore, the present invention can also be applied to pouring underwater concrete for seawalls.

When spraying seam bonding material inside a caisson, the entire circumference of the area to be sprayed is surrounded by the side walls of the caisson, so
It is possible to uniformly spread the seam binding material without being affected by water currents in the sea, but when spraying seam binding material in areas with fast water currents, use a hollow chisel that extends from above the water to a depth where it is less affected by water currents. Using a guide pipe such as a steel pipe with a steel pipe, the joint binding material may be introduced into the hollow chisel and dispersed through the guide pipe.

〔Effect of the invention〕

According to this invention, when the first layer of concrete 6 is poured on the underwater ground and the first layer of concrete 6 is still unhardened, a large number of pouring joint binders 4 are sprinkled on the concrete 6, The lower half of the joint binding material 4 is penetrated and buried in the first layer of concrete B, and after the first layer of concrete 3 has hardened,
Since the second layer of concrete 5 is placed on top of the first layer of concrete 3 and the pour joint bonding material 4, the concrete 5 of the first layer is penetrated and buried over both the first layer of concrete 3 and the second layer of concrete 5. Due to the key effect of the large number of joints 4, the first layer of conc IJ.

It is possible to significantly strengthen the shear strength at the joint between the concrete 5 of the first layer and the concrete 5 of the first layer. You only need to spray it on the top surface, so it can be used for construction of joints in deep water.

It is efficient and economical in construction, is safe as it does not require diving work, and can be easily constructed even when the surface of the first layer of concrete 3 is uneven or sloped. In addition, the construction efficiency is high, so the construction period can be shortened, which is especially advantageous when the splicing surface is wide or there are many spliced layers.Furthermore, special equipment is not required for processing horizontal splicing joints. This reduces construction costs. Effects such as being able to do this can be obtained.

[Brief explanation of drawings]

The drawings show one embodiment of the invention. Figure 1 is a vertical cross-sectional side view showing the caisson sunk into the underwater ground, Figure 2 is a plan view of the caisson, and Figure 3 is the state in which the first layer of concrete is placed on the excavated surface of the caisson. FIG. 4 is a vertical side view showing a state in which the lower half of the joint bonding material has been penetrated and buried in the surface of the first layer of concrete. FIG. 5 is a longitudinal sectional side view showing a state in which a second layer of concrete is placed on the first layer of concrete and pour joint binding material. In the figure, 1 is the caisson, 2 is the underwater ground, 6 is the first layer of concrete, 4 is the joint bonding material, 5 is the second layer of concrete, 8 is the work scaffolding frame, 9 is the concrete pump, 10 is the hose, 11 is a tremie tube, and 12 is a crane. Figure 1 Figure 2

Claims (1)

[Claims] When the first layer of concrete 3 is cast on the underwater ground and the first layer of concrete 3 is in an uncured state, a large number of pour joint binders 4 are sprinkled on the lower half of the pour seam binders 4. After the first layer of concrete 3 has hardened, a second layer of concrete 5 is poured on top of the first layer of concrete 3 and pour joint binding material 4. A horizontal pour joint construction method for underwater concrete.