JP2571742B2 - Construction method of underwater concrete using concrete block - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to underwater concrete, which is one of the construction methods for breakwaters, quays, dykes, seawalls, etc., in a shallow place where waves and currents act violently and where the water bottom is rock or cobblestone. It is related to the construction method.

[0002]

2. Description of the Related Art In a shallow sea area with a shallow reef with severe unevenness, it is dangerous to construct a breakwater using a large work boat or a caisson. Therefore, the underwater concrete method, which is one of the land-based methods, is often used. Since the bottom surface of a conventional underwater concrete form is horizontal, a gap of several tens of cm to about 1 m is formed between the form and the bedrock due to unevenness. The conventional method of closing this gap so that concrete does not leak is to excavate the bedrock horizontally. B Adhesive strength between the bedrock and concrete is sacrificed, but rubble is poured onto the bedrock, the top surface is leveled, and sponges or canvas for preventing concrete from leaking are stretched inside and outside the bottom of the formwork. C hitting a sheet pile at the bottom of the formwork,
Although there is a method to fill the gap by bagging concrete and sand bags, and there is a slight waves in the shallow location of the water depth, these work by the diver is impossible almost. D) A lightweight formwork was made at a stretch to a height above the high tide surface in a box shape on land, and was installed underwater. However, even if a small wave with a wave height of about 1 m came before the concrete was poured, a strong flow could occur in this gap. Occurs, the toro leaking device on the formwork foundation may come off, or the formwork may move, and as time comes, the formwork assembled in a box and placed underwater may have a large pressure receiving area. , The whole may be washed away. Oh, the method of installing the concrete block's bottom surface exactly on the unevenness of the bedrock is a very difficult task for surveying and manufacturing of the block's bottom formwork.
When the cobblestones move into the recesses due to the waves after surveying, they are accurately shaped, which induces a seesaw phenomenon, and the blocks become unstable.

[0003]

[PROBLEMS TO BE SOLVED BY THE INVENTION] An underwater concrete form is prevented from being broken by a wave or a flow. Avoid large gaps between the ground and the bottom of the formwork.
Most work should be done on land or from land without a diver. A method of suppressing a flow through a gap (hereinafter simply referred to as a “gap”) between the ground and a lower portion of the form block caused by a tide level difference between the inside and outside of the form due to a wave is adopted. Make it easy to inject mortar, etc. from land. Integrate the foundation with the embankment. The weight of the formwork block is reduced so that it can be freely suspended by the hoist.
Reduce the amount of water in the formwork block. The shape of the bottom of the formwork block is simplified to facilitate construction. (10) In the formwork block type II, the foundation ground shall be constructed so that the facility with a horizontal bottom installed on it may be installed on rock with large unevenness, and the foundation ground and each facility shall be integrated. I do.

[0004]

Means and Action for Solving the Problems A gantry for shallow surveying is temporarily provided, and the height of the ground contacting the underside of the form block from the land is set at an interval of 10 cm to 20 cm at four corners with an accuracy of cm unit. Measure the water depth. Similarly, the water depth of the bottom surface of the form block other than the four corners, the position of about 50 cm on the left and right thereof, and the water depth of the lower part of the partition wall are similarly measured at intervals of about 50 cm.

[0005] In order to suppress the flow through the gap, the top height of the form block is basically set below the water surface as shown in FIG. By setting the water level below the water surface, the weight can be reduced, and the difference in water level between the inside and outside of the form due to the waves can be reduced, so that a strong flow through the gap can be reduced.
Further, since the wave pressure decreases as the water depth at the top surface of the form block increases, the energy for breaking the form can also be reduced.

[0006] The formwork block is a heavy-weight unreinforced or reinforced concrete useless formwork instead of a light-weight steel or wooden formwork. Only the bottom of the four corners of the side wall is subjected to precise water depth survey. Based on the result, a protrusion is provided and installed on the ground, and the other side wall is made not to hit a convex portion of the ground, and is manufactured so as to substantially fit the ground. In other words, the bottom of the formwork block is straight, and the construction is easy by adjusting it to the rough slope of the ground.
A method in which mortar is injected into a mesh sheet that is loose and stretchable and is large enough to allow cement milk to penetrate into the ground, and then the cement milk of the mortar exudes from the mesh sheet and adheres to the bedrock to fill the gap. Take. By reducing the thickness of the gap, the compressive force on the sponge etc. attached to the lower surface of the wall increases, and the water flow acting on the gap material also decreases, so the sponge etc. holding effect that could not be achieved with the existing gap material mounting method is the first I was born. With the conventional method, it was extremely difficult to manufacture and install to fit small irregularities, but the projections at the four corners and the action of the mesh sheet made it easier to manufacture the block bottom.

After the form block is installed, the weight of the form block is increased by the filling of the filling stone into the hollow portion, the stability against waves is increased, and the amount of seawater flowing into and out of the gap at the lower side wall is reduced. The flow rate of the water stream is reduced by the frictional resistance of the filling stone. In addition, when a cellular block was installed on the upper part, it became possible to integrate the embankment from the foundation ground to the upper part by filling the mortar with the filling stone through the form block and the cellular block.

The form block II type shown in FIG. 2 is a construction method used when the inclination of the ground is large, or when there is a significant concave portion partially. It is also used to reduce the weight of a cellular block or the like installed on top. When the inclination of the foundation ground is severe or the ground cracks are large, the bottom width of the form block II is made somewhat wider. As means for reducing the flow through the gap under the side wall of the mold block II type, by providing a ceiling wall on the top surface of the block,
Since the wave pressure from the hollow portion of the block is not transmitted, the flow velocity is reduced.

When pouring mortar or concrete into the mold block II, a hose is inserted directly into the casting hole of the mold block II from the water to the ground and driven. At this time, the mortar is driven in at the beginning, and the cement block in the mortar that seeps out of the mesh sheet allows the form block II and the bedrock to adhere to each other, and then the concrete is poured to create a strong horizontal foundation. it can.

【Example】

FIG. 1 shows a breakwater with a width of 7.5 m and a height of 2.5 m at the top (+) of a breakwater installed on a seabed rock at a depth of 1.5 to 3.0 m, on which a cellular block is placed on a form block. This is a method according to the present invention. Since the rock at this location has severe irregularities, no gap material 1 was used, and the outer waterproof cloth 10 and the mesh sheet 2 attached to the bottom of the formwork block on the land were installed on the breakwater normal. Was installed and immediately filled with filling stones to approximately 80% of the height of the top of the cellular block to stabilize it.
At this time, the work had to be interrupted after the lid block was temporarily installed because it was timely. Several days later, water was discharged from the inspection hole and mortar injection hole 7, and concrete was poured to the top to complete the construction.
At the time of installation of the formwork block, the top surface of the formwork block was underwater, so a pole serving as a mark for positioning at the center of the front face was set up on a pipe embedded in the side wall in advance, and installed at an accurate position. .

[0011] In manufacturing the formwork block, the side wall heights at the four corners are determined based on the ground height measured in advance, and the thickness of the gap at the lower part of the side wall other than the four corners is determined at the convex part of the rock so as not to hinder the flow of mortar. 5 to 8 cm, 30 concaves
The bottom surface of the side wall was formed in a straight line so as to roughly conform to the inclination of the ground so as to be about cm or less. The mesh sheet is loosely attached to the bottom of the side wall so as to reach the bottom of the recess, and a waterproof cloth (10) is applied to the open sea side on the land so as to protect the mesh sheet from waves. A sand bag (not shown) was placed between the sand bag shown and the outer wall and pressed against the ground to prevent mortar in the mesh sheet from flowing out by waves.

When the width of the breakwater body becomes large and the weight of the form block exceeds the lifting capacity of the hoist, two form blocks are arranged in the transverse direction.

[0013] Immediately after the installation of the formwork block, the filling stone is put into the room of the formwork block about 1 m thick,
Inject a high-quality mortar into the mesh sheet attached to the bottom of the side wall from the lower injection hole (5) of the ground by inserting an injection hose to the bottom. When the injection of this part is completed, the hose is gradually lifted and the outlet 6 shown in FIG.
Inject mortar into the space of the filling stone from the lower side. After pouring the mortar into the voids of the filling stone that has been put into the formwork block, install the upper cellular block, etc., select a concrete construction method that will be an integral structure with the formwork block, and construct the embankment. Finalize. When calm can be expected all day, a cellular block or the like may be installed first, and an iron pipe or the like connected to the injection pipe of the formwork block may be installed in the hollow portion of this block, and a hose may be inserted into this for injection. .

The formwork block type II is partially used at the tip of FIG. 7 having a large inclination of the ground, or used as a horizontal form on the left and right of the breakwater. Used as a basis. In the case of FIG. 7, walls having a thickness of 20 cm were provided on both end surfaces of the mold block II.
When the form block II was continuously used as the left and right breakwater bases, a wall with a navel was provided on the tip side to facilitate the installation of the next form block II. The bottom thickness of the ground is set so that the gap thickness between the formwork block II type and the ground is precisely aligned with the ground at the four corners, and about 5 cm at the convex part of the ground at the other side walls, and 20 cm or less at the concave part except for special cases. It was molded in a straight line to roughly match the slope. In this embodiment, a formwork block II is installed on the left and right sides and the front of the breakwater, and a cellular block is mounted thereon. After that, the space from the ground surrounded by the formwork block II to the hollow portion of the cellular block is filled. Stone was injected and mortar was injected, so the embankment body was able to have a strong breakwater structure integrated from the foundation ground to the cellular block and upper concrete works.

[0015]

Since the present invention is configured as described above, the following effects are exhibited.

Conventionally, in the calculation of stability of a workpiece on rock in water, the weight of the embankment was multiplied by the coefficient of friction without considering the adhesion to the rock to determine the resistance to sliding out. There was a great difference between the technicians in terms of technology, and the degree of adhesion between the rock and concrete did not have a certain degree of reliability. However, it is known that, in practice, when an appropriate underwater concrete is constructed, its adhesion strength is extremely large. In the case of the construction according to the present invention, since the construction method is a simple construction method and almost from the land, the calculation can be performed based on the adhesive force of the concrete when the ground is strong rock. In addition, the caisson was installed on a flat surface or a rubble-leveled surface because the resistance to the slippage of the embankment due to the wave pressure was a form that meshed with the unevenness of the ground even if the adhesion to the ground was ignored. The coefficient of friction is considerably higher than in the case.

The use of concrete formwork blocks instead of wooden or steel formwork requires the use of land-based formwork, but the production of expensive underwater formwork, the framework,
Installation and removal by divers are not required.

When the form block is installed, there is almost no gap with the ground, so that the gap can be easily closed even with urethane foam or cloth having low strength.

Since the formwork block is a precast product having a large weight and a low top end, the work is fast, and the breakage and slippage of the formwork block due to waves are almost eliminated.

[0020] The material of the hollow portion to be the embankment is freely selected such as medium stone, gravel, low-concrete concrete, and the like, and the filling work is performed from the land.

Since the attached device of the form block is mounted on land, it is sufficient that the form block is settled even at the time of installation, and mortar or the like can be injected as long as the sea is not timed. Therefore, there is almost no work period delay due to aging.

Dangerous and time-consuming diving operations are rarely required.

The construction can be performed almost entirely on land or from land, so that the construction is accurate and of high quality, and the construction accuracy is improved.

According to the construction method of the invention, there is no need for a work boat or a high-class seafarer whose restraint period is long.

As a result of the above effects, cost reduction is achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a relationship with an upper embankment body when a form block is used.

FIG. 2 is a cross-sectional view showing a relationship with an upper embankment body when a mold block type II is used.

FIG. 3 is a perspective view showing an example of cloth installation, a situation before (left) and after (right) installation of a form block of a gap material, and a state of the cloth before (left) and after (right) mortar injection. It is.

FIG. 4 is a cross-sectional view showing a state before (left) and after (right) mortar injection of cloth by a method used when a gap height at a lower portion of a side wall of a mold block is large.

FIG. 5 is a schematic diagram of a cross section showing one of the embodiments using a reinforcing bar.

FIG. 6 is a sectional view of an embodiment of a seawall with a relatively small section using a formwork block.

FIG. 7 is a perspective view of an embodiment using both a mold block and a mold block II.

[Explanation of symbols]

 AI Formwork block AII Formwork block II type B Upper cellular block C Ground D Cover concrete M Mortar or concrete 1 Gap material 2 Mesh sheet 3 Cloth holding plate 4 Tightening bolt or concrete nail 5 Mortar injection hole 6 Mortar discharge port 7 Inspection hole and injection hole 8 Filling stone 9 Tack (fold) 10 Outer waterproof cloth 11 Reinforcement 12 Slide rebar 13 Slide ring 14 Outer waterproof cloth molded plate 15 Sand bag

Claims (2)

(57) [Claims] An underwater concrete structure characterized by constructing an underwater structure on a predetermined ground on which an underwater work such as a breakwater is to be installed by a combination of a series of construction methods mainly for land work described below. Construction method. According to the water depth of the predetermined ground that has been measured in advance, the bottom surfaces of the four corners are adjusted to the respective ground heights, and except for the four corners, the thickness of the gap between the side wall and the ground does not hinder the flow of mortar, and it is substantially uneven fit the side wall height of bottomless hollow reinforced or concrete formwork instead become block (hereinafter referred to as "mold blocks".) keep manufactured on land. At the bottom of the side wall of the formwork block, a formwork block attached to the ground in a bag-like shape with a slack so that a mesh sheet that is permeable to cement milk of mortar can be tightly attached to the uneven ground surface. Install in place. The filling stone is packed into the form block to the vicinity of the top. The mortar is injected into the bag-shaped mesh sheet and into the voids of the filling stone using the pipes embedded in the side walls and the like. 2. A part of the embankment which forms a horizontal top surface necessary for setting a submerged concrete formwork or a bottomless caisson on an uneven rock mass by a series of the following construction methods. Underwater concrete construction method characterized by doing. Based on the water depth of the predetermined ground measured in advance, the bottom surface at both ends in the longitudinal direction is set to the ground height so that the top surface serving as the base is horizontal, and the other side walls substantially match the unevenness of the ground A rectangular inverted U-shaped reinforced concrete or concrete block (hereinafter, referred to as "form block II type") having such a wall height is manufactured on land.
In the center of the top surface of the mold block II, there are provided several holes for inserting a hose for injecting concrete and holes for discharging residual water due to the injection. Furthermore, a form block having a stretchy mesh sheet with a looseness so as to be in close contact with the unevenness of the ground between the right and left side wall bottom surfaces of the form block type II and a cement-medium-permeable mesh sheet attached on land. Install the Type II in place. A concrete hose is inserted into the injection hole of the mold block II, and mortar is poured at first so that the mesh sheet is hidden, and then concrete is poured until the inside of the mold block II is filled.