JPH0458527B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method and apparatus for sealing a casing pipe of a caisson foundation with a steel pipe connection for constructing an underwater structure such as an underwater bridge pier.

[Conventional technology] Conventional caisson foundations include a method in which the caisson is installed after excavating the water bottom to a specified foundation surface, or a method in which a pile is driven into the main inside part of the caisson after it has been sunk to the water bottom, and the pile and caisson are integrated. There is a method to do this. These caissons were made to float by making them double-walled, or by temporarily covering the bottoms of the piles placed inside the caissons with steel plates to ensure a watertight chamber and obtain buoyancy. Moreover, according to these caissons, the necessary ground reaction force was obtained without forming an underground continuous wall.

By the way, the steel pipe jointed caisson foundation is a construction method for constructing the foundation of a large structure in deep water, and the outline of the construction process is as shown below.

(1) A caisson with multiple casing pipes arranged on the outer circumferential surface of the caisson with the axes oriented vertically is manufactured using a dock, etc., and transported to the construction site of the structure's foundation.
It is moored either by sinking to a predetermined water bottom position or floating at a predetermined water surface position.

(2) Insert a steel pipe pile inside each casing pipe, and bury the lower part of the steel pipe pile underground. Next, the gap between the inside of the casing pipe and the outside of the steel pipe pile is filled with mortar to fix the casing pipe and the steel pipe pile.

(3) Excavate the underwater ground in the area surrounded by steel pipe piles, and place underwater concrete in the excavated underground area and inside the caissons to serve as the foundation for a large structure.

However, when carrying out the above construction work, there were problems as shown below.

(1) The caisson is large in size and heavy, and it is necessary to utilize the buoyancy of the caisson to pull it out of the dock. For this reason, it is necessary to make the caisson a double-walled structure to obtain a buoyancy chamber, and to increase the buoyancy by temporarily capping the lower end of the casing tube provided on the outer wall of the caisson. However, it is not easy to easily and reliably remove this temporary cover after the caisson has been sunk.

(2) The mortar filled in the gap between the inside of the casing pipe and the outside of the steel pipe pile will be sealed to prevent it from leaking from the bottom end of the casing pipe and contaminating the water area, and to prevent the strength of the hardened mortar from decreasing. There must be. However, the seal portion is underwater, such as near the bottom of the water, and if the seal portion is deep in water, underwater work by divers becomes extremely difficult. For this reason, a sealing method that does not require diver work has been desired.

(3) A joint gap of several tens of centimeters is created between the steel pipe piles buried underground. When excavating the underwater ground in the area surrounded by steel pipe piles, the earth and sand outside the joint gap collapses into the excavated area, and the earth and sand outside the part where the steel pipe piles are embedded is scoured by water currents. As a result, the underground steel pipe piles were exposed in the water, and there was a risk that they would not be able to provide sufficient support to support the caissons on the piles. Therefore, it was necessary to create an underground continuous wall by sealing the vertical joints between the steel pipe piles.

Therefore, in order to put into practical use offshore caisson foundations with additional steel pipes, it is necessary to establish a method for sealing each part of the caisson as described above.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, particularly the problems of temporary capping and leakage of filled mortar in the casing pipe of a caisson foundation with a steel pipe addition. The purpose is to provide a rational sealing method and sealing device structure for practical use, and specifically aims to achieve the following points.

(1) Temporarily cap the lower end of the casing pipe to make the inside of the casing pipe watertight, and this temporary cap can be easily removed by operation from above the water.

(2) At the lower end of the casing pipe, the gap between the inner wall of the casing pipe and the outer wall of the steel pipe pile inserted into the casing pipe is sealed without diving, and the bonding mortar injected into the gap is prevented from leaking.

[Summary of the Invention] The seal construction method of the present invention is a method for attaching an axis to the outer circumferential surface of a caisson in steel pipe joint caisson foundation construction in which a plurality of steel pipe piles are buried underground along the outer surface of the caisson to construct an underground continuous wall. The process involves arranging multiple casing pipes in a vertical direction, and inserting an air bladder made of an elastic material into the lower end of the casing pipe, in which a supply/exhaust hose and a pull-out rope are stretched to the upper end of the casing pipe. The injection pipe is stretched to the upper end of the caisson, and a double-pipe sealing material mainly made of an elastic material is provided on the inner circumferential surface of the casing tube at the bottom of the air bladder, and the inside of the air bladder is filled with air. The process involves bringing the air sac into close contact with the inner peripheral surface of the casing pipe, and after the caisson is submerged or in a floating state, the air in the air sac is removed and the air sac is pulled out from the casing pipe, and the steel pipe is inserted into the casing pipe. A process of inserting a pile and burying the lower part of the steel pipe pile in the ground, a process of filling the inside of the double pipe sealing material with fluid and expanding the double pipe sealing material to close the gap, The method includes the step of filling the gap between the casing pipe and the steel pipe pile above the heavy pipe sealing material with mortar to join the casing pipe and the steel pipe pile.

Further, in the sealing device structure of the present invention, an air bladder mainly made of an elastic material is fitted into the lower ends of a plurality of casing pipes arranged on the outer peripheral surface of the caisson with their axes in the vertical direction. A hose for air supply and exhaust and a rope for pulling out the air bladder from the casing tube are extended from the air bladder to the upper end of the casing tube, and are attached to the inner peripheral surface of the casing tube below the air bladder.
A double pipe sealing material of an annular bag mainly made of an elastic material is fixed to penetrate a steel pipe pile inserted into a casing pipe, and an injection pipe for filling the double pipe sealing material with fluid is fixed to the double pipe sealing material. The structure extends from the top to the top of the caisson.

[Embodiment of the Invention] FIG. 1 is a perspective view showing a floating state of a caisson in an embodiment of the invention. 1 is a water surface, and 2 is a caisson floating on the water surface 1. 3 is the caisson body, which is a rectangular parallelepiped steel formwork with double side walls. On the outer circumferential surface of the caisson body 3, a large number of casing tubes indicated by 4 are arranged closely in parallel with each other with their axes in the vertical direction. Reference numeral 5 denotes a cylindrical air bladder, which is fitted into the lower end of each casing pipe 4. The air bladder 5 is mainly made of a rubber elastic material, has a reinforcing layer such as cloth or fiber cord, and is filled with air so that the outer circumferential surface of the air bladder 5 is brought into close contact with the inner circumferential surface of the casing pipe 4. ing. Further, numeral 6 denotes an inflatable double-tube sealing material having a donut-shaped bag mainly made of a rubber elastic material, and is fixed to the inner circumferential surface of the casing tube 4 at the lower part of the air sac 5.

Figure 2 is a sectional view taken along line A-A in Figure 1.
and shows the configuration of the double pipe sealing material 6. 3a is a caisson bottom plate, and the lower ends of the double side walls of the caisson body 3 are connected by the caisson bottom plate 3a, making the inside of the double side walls watertight to obtain a buoyancy chamber. 3b is concrete filled in the lower part of this buoyancy chamber, which lowers the center of gravity of the caisson 2 and stabilizes the caisson 2 as a floating body when floating. Reference numeral 5a denotes a hanging fixture, which is provided on the upper part of the air bladder 5. A rope 5b hanging down from the upper end of the casing pipe 4 above the water surface and a hose 5c for supplying and discharging air inside the air bladder 5 are connected to the hanging fitting 5a.
A stopper 5d is a steel plate divided into one or more parts having a predetermined thickness and fixed along the inner peripheral surface of the casing pipe 4, and its lower end surface is in contact with the upper surface of the air bladder 5. 6a is a spacer, and the structural dimensions of the spacer 6a are the same as those of the stopper 5d. The spacers 6a are provided at two locations, at the top and bottom of the double tube sealing material 6, and have a thickness that is at least greater than the thickness of the double tube sealing material 6 when it is collapsed before being activated. Furthermore, the inner diameter of the portion where the stopper 5d and the spacer 6a are fixed to the inner surface of the casing pipe 4 is made larger than the outer diameter of the steel pipe pile described in FIGS. 3 and after, so that when the steel pipe pile is inserted into the casing pipe 4, Steel pipe pile is stopper 5d and spacer 6a
Try not to get caught.

Next, construction of the caisson foundation will be explained. For example, in a shipyard dock, caisson 2
When constructing a dock and pulling out the caisson 2, if the inside of the casing pipe 4 is made airtight by filling the lower end of each casing pipe 4 with an air bladder 5 before injecting water into the dock, the inside of the casing pipe 4 will also become a buoyancy chamber. functions as For this reason, water was injected into the dog and caisson 2 was installed.
can be floated on the water surface and pulled out of the dock. In particular, when the caisson 2 is large in size and heavy, the weight exceeds the lifting capacity of the crane, and it is necessary to utilize the buoyancy of the caisson 2. Furthermore, since the water depth inside the dock is shallow compared to the height of the caisson 2, it is necessary to secure a buoyancy chamber at the bottom of the caisson 2 when using buoyancy. To meet this requirement, after fitting the machine body 5 to the lower end of the casing pipe 4,
It is advantageous to supply air to the fuselage body 5 and bring it into close contact with the inner peripheral surface of the casing pipe 4.

The caisson 2 pulled out from the dock is floated and towed to the construction site by a tug boat, water is poured into the buoyancy chamber of the caisson 2, and the caisson 2 is sunk to the bottom of the water. Then, the air is discharged from the inside of the air sac 5, the air sac 5 is crushed by the action of water pressure, and the rope 5b is wound up to pull out the air sac 5 from the casing pipe 4. Next, steel pipe piles are sequentially built into the casing pipe 4 and pile driving is performed to form an underground continuous wall.
In this case, the air bladder 5 inside the casing pipe 4 is removed and the steel pipe piles are driven one after another, not necessarily after the caisson 2 has been sunk to the bottom of the water as described above, but while it is still floating. There are ways to go about it.

Even if a rubber membrane or a steel lid is provided at the lower end of the casing pipe 4 instead of the air bladder 5 and the lid is temporarily tightened, it is possible to secure the same buoyancy chamber as the air bladder 5. However, removing the caisson 2 after it has been towed is not easy as it requires diving, and there is no guarantee that it can be done reliably. On the other hand, if the air bladder 5 configured as in this embodiment is used, the upper ends of the supply/exhaust hose 5c and the pulling rope 5b are guided above the water surface, so all removal work is done on the water surface. This can be done above.

At this time, a hanging fitting and a rope similar to those provided at the upper end are provided at the lower end of the air bladder 5, and the lower rope is pulled out of the casing pipe 4, and then
It is rolled up along the outer surface of the casing pipe 4 and fixed to the caisson 2 above the water surface. By doing this, it is possible to eliminate the risk that the air sac 5 that has been deflated by expelling the air will rapidly float up inside the casing pipe 4, thereby increasing the safety and certainty of the recovery work of the air sac 5. can be increased.

Fig. 3 is a longitudinal section showing a state in which a steel pipe pile indicated by 8 is inserted into the casing pipe 4 from which the caisson 2 has been sunk and the air bladder 5 has been removed, and the steel pipe pile is buried underground at the bottom of the water, indicated by 7. It is a diagram. In addition, the casing pipe 4
When inserting and dropping the steel pipe pile 8 into the interior, the stopper 5d and spacer 6a reduce eccentricity between the casing pipe 4 and the steel pipe pile 8, and the double pipe sealing material 6 installed between the spacers 6a before fluid injection This prevents the steel pipe pile 8 from coming into contact with the double pipe sealing material 6 and damaging the double pipe sealing material 6.

FIG. 4 is an enlarged sectional view of section B in FIG. 3, showing the operating state of the double pipe sealing material 6. In Figure 4, 6
c is air injected into the inside of the double pipe sealing material 6;
The double pipe sealing material 6 is expanded with fluids such as water and mortar, and the gap between the inner surface of the casing pipe 4 and the outer surface of the steel pipe pile 8 is sealed. 6b is a pipe such as a steel pipe or a rubber hose,
The lower end is connected to a double pipe sealing material 6, and the upper end is piped to the upper end of the caisson 2 above the water surface. 6d is mortar injected into the gap between the inner surface of the casing pipe 4 and the outer surface of the steel pipe pile 8.

Here, the steps after sinking the caisson 2 will be explained in detail. After the lower part of the steel pipe pile 8 is buried in the ground, fluid is injected into the double pipe sealing material 6 and expanded to close the gap. This sealing work can be done by using the double pipe sealing material 6 configured as in this embodiment.
It is sufficient to simply inject mortar from the injection pipe 6b placed above the water surface, eliminating the need for underwater work.

Next, mortar 6d is injected into the gap above the double pipe sealing material 6, and the casing pipe 4 and steel pipe pile 8 are
combine. At this time, since the double pipe sealing material 6 prevents the mortar 6d injected into the gap from leaking, sufficient bonding strength of the mortar 6d can be obtained, and water pollution due to the mortar 6d being washed away can be prevented.

After the above work, the vertical joints of the steel pipe piles 8 are sealed using the steel pipe joint sealing material 9 to construct an underground continuous wall.

[Effects of the Invention] As explained above, the present invention aims to put into practical use a caisson foundation with a steel pipe extension, which has not been used offshore, and provides the following effects.

(1) According to the construction method of the present invention, it is possible to fill the air sac with air to make the inside of the casing pipe watertight, and to float the caisson using buoyancy.
A heavy caisson can be easily pulled out from the dock. Furthermore, air sacs can be easily and reliably removed by operating the caisson on the water's surface after the caisson has been sunk into place.

(2) According to the construction method of the present invention, the gap between the inner surface of the casing pipe and the outer surface of the steel pipe pile at the lower end of the casing pipe is
It seals when operated above the water surface to prevent mortar from leaking. In addition, sealing work at great depths can be easily performed as there is no need for divers to perform the work.

(3) According to the construction method of the present invention, air bladder supply and exhaust,
The equipment for removing air capsules and injecting mortar into the double pipe sealing material can all be placed on the upper side of the caisson, and the preparation, operation, and removal of these equipment can be carried out during offshore steel pipe joining. To make the caisson foundation construction system efficient and economical.

(4) According to the device structure of the present invention, it is possible to remove the air sac temporarily closed from the casing pipe, and seal the gap between the inner surface of the casing pipe and the outer surface of the steel pipe pile at the lower end of the casing pipe (double pipe seal). (injection of fluid into the material) can be performed by operating above the water surface.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the caisson in a floating state showing an embodiment of the present invention, Fig. 2 is a sectional view taken along the line A-A in Fig. 1, Fig. 3 is a longitudinal sectional view of the caisson in a submerged state, and Fig. 4 is a caisson in a suspended state. It is an enlarged cross-sectional view of part B in the figure. 2...Caisson, 4...Casing pipe, 5...
Air bladder, 6...double pipe sealing material, 8...steel pipe pile.

Claims (1)

[Scope of Claims] 1. In a steel pipe caisson foundation construction in which a plurality of steel pipe piles are buried in the ground along the outer surface of the caisson to construct an underground continuous wall, a plurality of steel pipe piles whose axes are perpendicular to the outer circumferential surface of the caisson are constructed. A process of arranging the casing pipes of a step of providing a double-pipe sealing material mainly made of an elastic material stretched at the upper end on the inner circumferential surface of the casing tube at the bottom of the air bladder; and filling the inside of the air bladder with air to close the air bladder. After the caisson is submerged or in a floating state, the air in the air sac is removed and the air sac is pulled out from the casing, and a steel pipe pile is inserted into the casing. burying the lower part of the steel pipe pile underground; a step of filling the inside of the double pipe sealing material with a fluid to expand the double pipe sealing material and closing the gap; A casing pipe seal for a caisson foundation with a steel pipe addition, comprising the step of filling the gap between the casing pipe and the steel pipe pile above the heavy pipe sealing material and joining the casing pipe and the steel pipe pile. Construction method. 2 An air bladder mainly made of an elastic material is fitted into the lower end of a plurality of casing pipes arranged on the outer peripheral surface of the caisson with their axes in the vertical direction, and a hose for supplying and exhausting air to the air bladder and a A rope for pulling out the air bladder from the casing tube is extended from the air bladder to the upper end of the casing tube, and a rope is attached to the inner circumferential surface of the casing tube below the air bladder.
A double pipe sealing material of an annular bag body mainly made of an elastic material is fixed to penetrate a steel pipe pile inserted into a casing pipe, and an injection pipe for injecting fluid into the double pipe sealing material is fixed to the double pipe sealing material. A casing pipe sealing device structure of a caisson foundation with a steel pipe connection, characterized by extending from the caisson to the upper end of the caisson.