JPS59134088A - Method of building caisson and service ship for building caisson - Google Patents

Abstract

PURPOSE:To build a caisson smoothly by sinking downward a floatable multiple body system service ship formed in the central portion with an empty space against its buoyancy and building the caisson on a bottom bed interlocked with the empty space through a cable while adjusting the buoyancy of the service ship and the bottom bed. CONSTITUTION:A multiple body system service ship body H which floats on water with its buoyancy and is formed in the central portion with an empty space is sunk downward against its buoyancy by a tension leg unit 6 consisting of weights 64, mooring cables 62, etc. A bottom bed 4 having buoyancy is disposed in said space through an elevator 5. While the buoyancy of said bottom bed 4, weight or buoyancy of a caisson C and buoyancy of the service ship body H are ajusted, tension is maintained at a predetermined value to sink downward the service ship body H to prevent sway caused by waves and build smoothly the caisson C under the stable condition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for constructing a caisson, particularly a bottomed floating caisson constructed on water, and a work boat used in the method.

This type of caisson, the so-called box caisson, is mainly used in port construction, but conventional construction methods include: - building the caisson on land and launching it into the water using a slipway; ■ A method of building a caisson in a dry dock and, after completion of construction, injecting water into the dock to float and pull out the caisson, ■ A method of building a caisson on a floating dock, sinking the floating dock after construction, and raising the caisson to the surface; ■ A method of floating the caisson at sea. A method of constructing a work bridge for construction work, towing a semi-finished caisson that can be floated and transported on land or at a dock to the bridge, and completing the superstructure of the caisson by splicing while it is moored to the bridge. There are various methods such as However, when the water depth of a port is deep, the caisson used for port facilities becomes large, and the caisson construction equipment used in the conventional construction method described above requires large-sized equipment, which poses difficulties in actual construction.

In order to solve this problem, we prepared a work boat arranged in parallel and a bottom platform that moves up and down in conjunction with the work boat and has buoyancy.
A method was developed in which the caisson was built on the bottom platform and the bottom platform and caisson were gradually lowered.
4 and Japanese Patent Application Laid-Open No. 53-34316 (hereinafter referred to as prior art). However, in these prior art techniques, the equipment can be made smaller if construction is carried out on a flat water surface without waves, but in conditions with waves, the work boat, and the bottom platform and caisson that are linked to it, are subject to external forces in the vertical direction. This has the disadvantage of making the caisson construction work unstable.

In order to prevent this oscillation, the work boat is stabilized, but for this reason, in the prior art, no special measures have been taken other than increasing the size of the work boat itself.

The present invention has been made in order to eliminate the drawbacks of the above-mentioned prior art, and provides a caisson that can be smoothly constructed by preventing vertical movement caused by waves without increasing the size of the work vessel itself. The technical problem is to provide a construction method and a work boat for the same.

The caisson construction method of the first invention adopts the following configuration (technical means) in order to achieve this technical problem. In other words, a tension force is applied from below to the work boat body, which floats on the water with buoyancy and has a hollow space formed in the center, and sinks downward against the buoyancy. A method of constructing a caisson with a bottom on a bottom platform that has buoyancy and is interlocked with the main body of the multi-hulled work vessel by a tension member, which is arranged in a hollow space, the buoyancy of the bottom platform and the weight or buoyancy of the caisson. In addition, while adjusting the buoyancy of the work boat body, the tension that causes the work boat body to sink downward is maintained at a predetermined value.

This method is described as follows for pigments used in caisson construction. ■While the buoyancy of the multi-hulled work boat is minimized, tension means such as a tension reflex device is anchored to the work boat, and tension is applied to the tension means by restoring the buoyancy of the work boat. be done. ■Float the bottom platform on the water surface in the hollow space in the center of the work vessel, and begin construction of the caisson on the bottom platform.

■Build the caisson base on the base platform. As a result of this work, the bottom platform sinks due to the load, but even when the weight W1 of the caisson bottom is loaded, the bottom platform makes the buoyancy E a sufficiently large value relative to the weight W1, so that the caisson bottom is placed on the main body of the work vessel. No weight is loaded. 0th order: Build the caisson superstructure.

In this case, the weight W2 of the upper structure is added to the weight W1 of the bottom plate.
This puts a load on the bottom plate and causes the bottom plate to sink. When the weight of the caisson (W++W2) becomes larger than the buoyant force Fl of the bottom platform, a load L1 is applied to the main body of the workboat via the tension member. The size of this beam is (W, + W2R). By lowering the work boat into the water using a tension means with a force T1 that is sufficiently larger than the resultant force (difference) between the maximum fluctuation value L2 of the buoyancy force due to the waves that the work boat and the caisson are subjected to, and the above-mentioned load, the work boat is lowered vertically by the waves. It is able to maintain stability without swaying even when subjected to external force in any direction. ■°The load on the work vessel due to the weight of the caisson increases as the construction progresses. For this reason, the tension T1 of the tensioning means is always maintained within a predetermined range by discharging the ballast inside the workboat body to increase the buoyancy of the workboat. ■
As the caisson construction progresses, the height of the caisson gradually increases, and the overturning moment due to wind force increases. In order to prevent this, the bottom platform will be lowered into the water as construction progresses, and the height of the caisson above the water surface will be kept below a certain value to prevent an increase in the overturning moment. ■The superstructure of the caisson is built in a layered manner, but as the caisson construction progresses (!:,:!:) and the caisson is gradually lowered into the water, the load on the base plate gradually decreases due to the increase in the buoyancy of the caisson itself. The weight decreases.If the construction continues, the caisson will become floating and cannot maintain its stability.For this reason, ballast is supplied to the inner cavity of the caisson to maintain a constant weight and stabilize it.Working on the completed caisson In order to pull it out from the ship, ballast is supplied to the bottom platform to make the bottom platform sink, and the ballast inside the caisson is discharged to make the caisson floating.Furthermore, the ballast in the main body of the workboat is discharged to make the workboat float. Levitate and assist in pulling out the caisson.

It can be seen that the technical means of the method of the present invention are commonly adopted in the caisson construction steps (1) to (3) above.

Further, a caisson construction work boat according to a second aspect of the invention is for achieving the above method, and has the following configuration. In other words, ■ In the main body of a multi-hull work boat, which is formed by connecting a plurality of floating bodies constituting the hull arranged in parallel together by connecting beams at the bow and stern of each body, and forming a hollow space in the center. , ■ In the central space, a bottom platform having a buoyancy adjustment function and which can be raised and lowered by a lifting device is suspended in conjunction with the work boat body; It is characterized by the installation of a tension leg device that pushes the ship body downwards.

With this configuration, during the installation work of the workboat in a designated water area and the construction work of the caisson, the tension of the tension leg device is always maintained at a predetermined value by appropriately adjusting the buoyancy of the workboat main body, the base platform, and even the caisson itself. can be granted.

According to the present invention, the following unique effects are achieved.

■ The work vessel itself avoids vertical fluctuations of waves and does not sway, so caisson construction is stable.

■ Even if the caisson becomes larger and taller, the caisson can be constructed by making the workboat itself as small as possible by utilizing the buoyancy of the bottom platform, the workboat itself, and the caisson itself.

The present invention adopts the following embodiments.

■ The main body of the work boat must be a twin-hull type consisting of two floating bodies.

■ A buoyancy reducing part such as a recess or an opening is formed at the stanchion position of the floating body. According to this aspect, since the waves fluctuate within the buoyancy reduction section, fluctuations in the buoyancy exerted on the floating body are reduced as much as possible, and together with the action of the tension leg device, this contributes to the stability of the work boat body.

Therefore, the buoyancy reduction section includes any aspect for reducing buoyancy.

Embodiments of the present invention will be described below based on the drawings.

FIGS. 1 and 2 show a plan view and a side view of a caisson construction work boat which is an embodiment of the present invention.

Here, H is a work boat main body, which is made up of two parallel floating bodies 1 and the bow and stern parts of each floating body, which are integrally connected by connecting beams 2 and 3. (2) is a space formed in the center of the main body H of the work vessel.

The floating body 1 constitutes the body of a work boat, and has ballast (
Ballast tanks containing water (usually water) are located at the bow, amidships, and stern. Reference numeral 11 denotes a recess formed on the outer surface of the floating body 1 at the swamping position. Instead of the recess 11, an opening passing through the side surface of the floating body 1 may be used.

The bow connecting beam 2 and the stern connecting beam 3 rigidly connect the upper parts of the two floating bodies 1, and a space for drawing out the caisson C is formed below each of them.

Reference numeral 4 denotes a bottom platform serving as a workbench on which the caisson frame is constructed, and is suspended in the central space (2) of the main body of the work vessel H with a bottom platform lifting device 5. Further, the inner space of the bottom platform 4 forms a ballast storage space, and the buoyancy can be adjusted by itself.

The bottom platform lifting device 5 is a suspension device (such as a chino or wire).
It consists of a tension member 51 and a winding device 52 that winds up the suspension member 51.

Reference numeral 6 denotes a tension leg device consisting of an upper pulley 61, a lower pulley 62, a tension member 63 made of a chino or wire, and a sinker 64. The upper pulley 61 is disposed within the floating body 1, and the lower pulley 62 is fixed to the sinker 64. The tension member 63 is wound around the upper pulley 61 and the lower pulley 62 in multiple layers to facilitate winding up of the sinker 64.

7 is a mooring device, which includes a tension member 71 such as a wire.
An anchor (not shown) is attached to one end of the winding device 7, and two sets of winding devices 7 are provided at each of the four corners of the work boat body H at the other end.
2 to secure the work boat in the horizontal direction.

Reference numerals 81 and 82 denote a bow breakwater gate and a stern breakwater gate, respectively, which close the openings at the bow and stern of the work boat body H, and prevent waves from hitting from outside. These games 1-81, 82 are pivotally connected to the upper portions of the sides of the bow connecting beam 2 and the stern connecting beam 3 by pin connections, and the pin connecting portions 81A.

The opening can be opened by rotating upward and outward about 82A.

Hereinafter, a method for constructing a caisson using the caisson construction work boat of this embodiment will be described based on the drawings from FIG. 3 onwards.

(5) Mooring work (see Figure 3) ■ Bottom platform 4, tension leg device 6 and breakwater 1
-81.82 is towed and the ballast tank of the work boat is filled with ballast (usually water) at a predetermined sea level, and the ship is lowered to a predetermined level while adjusting the hull level.

■ The sinker 64 of the tension leg device 6 installed at the four corners of the hull is lowered and the sinker hanging device 63 is lowered.
The tension is sufficiently tightened to a predetermined value, and the hull is secured against external forces in the vertical direction of the hull.

- Eight sets of mooring devices 7 installed at each of the four corners of the hull are used to set anchors at eight points to secure the hull sufficiently against external forces in the horizontal direction.

- With the bottom plate 4 fully rolled up, ballast (usually water) is injected into the bottom plate 4 to maintain a constant level of water.

At this time, the water level of the bottom plate 4 is also adjusted by adjusting the ballast.

■ Close the breakwater gates 81 and 82 at the bow and stern to prevent waves from hitting the water surface in the center of the ship and maintain a flat water surface.

(B) Construction of caisson bottom (see Figure 4) ■ Bottom base 4
A concrete formwork is installed on top, reinforcement is placed, concrete is poured, and the bottom part CI of caisson C is constructed.

(2) At this time, as the construction progresses, the load on the base base 4 increases and the water on the base base 4 gradually becomes deeper, so the base base lifting device 5 is brought out and the load is balanced by the buoyancy of the base base.

■ When the load increases further and reaches a state where the load exceeds the predetermined swamp of the bottom platform 4 (so that the bottom platform is not submerged in water), the bottom platform lifting device 5 stops being extended and the excess load is transferred to the work boat via the lifting device. Make it a burden.

Since the work boat is loaded in advance by the tension leg device 6, the average hiccup does not change even if a load corresponding to the tension of the tension leg is applied. However, since the tension in the tension leg decreases, in order to maintain the tension, the ballast of the work boat is discharged to increase buoyancy and the tension is increased to a predetermined value to maintain the oscillation deterrent force.

(q Construction of the caisson superstructure (see Figure 5) ■ The upper part C2 of the caisson is constructed in a layered manner using the slide form construction method on top of the completed caisson base C1.

■ As the construction progresses, the load on the base platform 4 will increase.

In order to balance this load, the ballast of the work boat is drained and the tension of the tension leg 6 is maintained.

■ As the construction progresses, the height of the caisson C increases and the exposed part above the water receives the overturning moment due to the wind force, making it unstable. Therefore, the bottom platform lifting device 5 is extended and the completed part of the caisson superstructure C2 is placed in the water. Precipitation reduces the effects of wind power.

■ As the height of the caisson increases and it sinks into the water, the buoyancy of the caisson itself gradually increases, and the load on the base platform gradually decreases from its maximum value. Therefore, the specifications of the work boat are planned based on this maximum load.

(D) Completion of caisson construction work (see Figure 6) ■ No. 5
By repeating the layered construction method shown in the figure, the caisson C gradually becomes higher, and as the underwater part increases, the buoyant force becomes greater than the weight of the caisson, and it floats off the base and becomes unstable. In order to ensure that the caisson is seated on the bottom platform, ballast is placed inside the caisson to prevent it from floating.

■ By repeating the above work, the caisson will be built in a stable condition and the caisson construction method will be completed.

(5) Caisson drawer (see Figure 7) ■ Caisson C
In order to pull out the work boat from the work boat, first, ballast is injected into the bottom platform 4 and the bottom platform is sunk.

■ Discharge the ballast in caisson C and make the caisson buoyant.

■ Open the breakwater gate 81 (82).

■ Create a gap between the bottom of the workboat's connecting beam and the top of the floating caisson so that the caisson can be pulled out from the workboat. For this reason, the ballast of the work boat will be discharged to reduce stagnant water.

■ Pull out caisson C using a tugboat (not shown).

The present invention is not limited to the embodiments described above, and various design changes can be made within the scope of the basic technical idea of the present invention. That is, the following aspects are included in the technical scope of the present invention.

■ The breakwater gate can be omitted as appropriate.

■ In addition, instead of the breakwater gate, breakwater blocks made of floating bodies can be installed at the bow and stern of the work boat.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a plan view of an embodiment of the caisson construction work boat of the present invention, FIG. 2 is a side view of the workboat as seen from the bow side, and FIG. Figure 7 is a construction drawing showing method 11N of the caisson construction method. 1... Floating body 2, 3... Connecting beam 4.
...Bottom board stand 5...Bottom board lift device 6.
...Tension reflex device H...Main body of work vessel I...Central space C...Caisson patent applicant Co., Ltd. Metxus Kazushige Okusako, patent attorney Pond 1) Jinshi Figure 7 81

Claims (1)

[Claims] 1. A tension force that causes the main body of a multi-hulled work boat (■), which floats on the water with buoyancy and has a cavity (I) formed in the center, to sink downward against the buoyancy is applied to the work. While being applied from below on the ship body side, a bottomed base is placed on the bottom platform (4) which is arranged in the central cavity (I) and has buoyancy and is linked to the multi-hulled work vessel body (■) with a tension member. A method of constructing a caisson (q), which involves adjusting the buoyancy of the bottom platform (4), the weight or buoyancy of the caisson (q), and the buoyancy of the main body of the work vessel.
A method for constructing a caisson, characterized in that the tension that causes the work boat body side to sink downward is maintained at a predetermined value. 2. Connecting beams (2, 3) at the bow and stern of a plurality of floating bodies (1) that constitute the body arranged in parallel
In the multi-hull work boat main body H, which is integrally connected to form a cavity (I) in the center thereof, the central cavity (I) has a buoyancy adjustment function and a lifting device ( 5), a bottom platform (4) that can be raised and lowered is suspended in conjunction with the work boat main body side, and a tension leg device is provided at the lower part of each of the floating bodies (1) to push down the work boat main body side. A work boat for caisson construction, characterized in that (6) is installed. 3. The caisson construction work boat according to claim 2, wherein the work boat main body (2) comprises two floating bodies (1). 4. The caisson construction work boat according to claim 2 or 3, wherein a buoyancy reducing portion is formed at the stanchion position of the floating body (1). 5. The caisson construction work boat according to claim 4, wherein the buoyancy reducing portion is a recess formed on the outer surface of the floating body (1). 6. The caisson construction work boat according to claim M4, wherein the buoyancy reducing portion is an opening penetrating from the outer surface to the inner surface of the floating body (1).