JPH0674595B2 - Steel plate concrete ship foundation method for soft ground - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a method for constructing a foundation of a railway bridge or various plants and other structures in the field of civil engineering, and a foundation of a high-rise building, nuclear power-related or tower in the field of construction It is about.

[Conventional technology]

When constructing such a foundation on soft ground, it is necessary to excavate to the support layer and make a concrete structure at that level.

Further, in the conventional method, a retaining pile for stopping water is required for excavation, and the ground at the bottom of the structure is often improved to secure bearing capacity and water stopping.

Further, as a method for making a concrete structure at a depth below the water table after excavation, there are a method of placing concrete in a state of draining water by a pump method and a method of placing underwater concrete.

There is also a pneumatic caisson method as a method of manufacturing a structure at the same time as excavating a structure without retaining a mountain.

[Problems to be Solved by the Invention]

In the mountain retaining method for constructing the retaining mountain for water stopping, it is necessary to construct the mountain retaining wall to a depth that reaches the impermeable layer, and if this impermeable layer is deep and the wall does not reach the impermeable layer, substitute it. Although it will improve the water resistance of the bottom ground, such ground improvement work is a large-scale incidental work, and the cost and construction period are enormous.

In addition, as a construction method of a mountain retaining wall for the purpose of stopping water, there is a construction method that uses a multi-axis auger to continuously wrap pillar wall walls such as Mortayu or soil concrete while successively wrapping them. Is relatively simple, but there is a problem in vertical excavation accuracy of the auger when the depth is large, and there is a risk that the mutual alignment of the column walls may be incomplete, and it is difficult to secure water shutoff at the boundary.

In the pneumatic caisson method, excavation work inside the caisson must be performed mainly by manpower, and the construction efficiency is poor.

The object of the present invention is to eliminate the disadvantages of the conventional example, no need for mountain retaining walls, etc. until reaching the impermeable layer, no need for improvement of the bottom ground, and a soft ground with sufficient water stopping effect. To provide a steel plate concrete ship foundation method in Japan.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention places steel pipe piles at appropriate intervals at the construction point of a structure, excavates the ground using a temporary gantry installed at the top of the steel pipe pile, and removes this temporary gantry. After that, the steel plate part of the steel plate concrete ship foundation is assembled at that position, and it is suspended and supported by the descending device provided at the tip of the steel pipe pile, and then the steel plate part of the steel plate concrete ship foundation is suspended by the descending device to be launched. , Concrete is placed in the steel plate part of the ship foundation that is floated in water to complete the ship foundation, and the steel plate concrete ship foundation is reinforced and the concrete is placed and the steel plate concrete ship foundation is sunk by its own weight. The purpose is to construct concrete by placing concrete in the lower area and surrounding area of the sunk ship foundation and backfilling the surrounding area.

[Action]

According to the present invention, the steel plate portion of the steel plate concrete ship foundation is assembled and launched, and the steel plate concrete ship base is completed and then laid down to form the structure foundation, thus reaching the impermeable layer. There is no need for a retaining wall to stop the water.

Further, since the steel plate concrete structure that forms the ship foundation and the concrete itself in the lower region are replaced by the supporting ground, it is not necessary to improve the bottom ground, and the water blocking effect is high due to the surrounding iron plates that form the steel plate concrete structure.

Moreover, the excavation can be performed using a large machine from the ground.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 to 13 are longitudinal side views of respective steps showing one embodiment of a steel plate concrete ship foundation method for soft ground according to the present invention.

First, as shown in FIG. 1, steel pipe piles (φ≈1.0 m) 1 should be appropriately spaced (about 10.0 m × 10.0 m) at the construction point of the structure, and the pile length should be longer than the excavation depth. To set.

Next, as shown in FIG. 2, a temporary gantry 2 is installed on the top of the steel pipe pile 1, and as shown in FIG. 3, the gantry 2 is used and the ground is excavated from the surrounding ground using a large machine. I do. At this time, since the ground to be excavated has a high normal water level, the excavation will be underwater.

In addition, a temporary mountain stopper 3 is provided around the periphery as needed prior to excavation, but this may be a simple one and the water-stop effect need not be expected.

After excavation, as shown in FIG. 4, underwater concrete is cast on the slope and bottom to a thickness of about 200 mm to form a protective layer 4, and the temporary gantry 2 is removed.

Then, as shown in FIG. 5, only the steel plate portion 5a of the steel plate concrete (SC) ship foundation 5 is assembled at the position where the temporary gantry 2 was.

As shown in FIGS. 14 and 15, in the steel plate concrete ship foundation 5, the outer pipe 6 is raised from the bottom surface so that the tip of the steel pipe pile 1 projects through the inside. By locking the tip of the outer pipe 6 with the descending device 7 provided in the above, the entire steel plate portion 5a of the steel plate concrete ship foundation 5 is suspended and supported by the steel pipe pile 1.

Although various structures are conceivable as the lowering device 7, the hanging wire 7b and the jack 7a for adjusting the hanging wire 7b are mainly used.
As shown in FIG. 14, a pulley 8 for a guide roller may be provided at the tip of the steel pipe pile 1 as shown in FIG.

It is also possible to use a center-hole type jack as the jack 7a and detachably lock the hanging wire 7b with a fixing tool that engages with and disengages from the jack.

As shown in FIG. 6, the steel plate portion 5a of the steel plate concrete ship foundation 5 already assembled by the descending device 7 is hung and launched, and as shown in FIG. 7, the steel plate of the ship base 5 floated on this water. Concrete 10 is placed in the part 5a and the ship foundation 5
To complete.

Before the descent of the steel plate concrete ship foundation 5, the outer pipe 6 is added to the upper part so that the tip of the outer pipe 6 is always above the normal water level.

As shown in FIG. 8, the bar arrangement 9 is performed inside the ship foundation 5 in order to manufacture the foundation of the structure, and at the same time, the ruler control 17 which determines the sinking level of the steel plate concrete ship foundation 5 is placed.

Further, the portion of the tip of the steel pipe pile 1 that is above the normal water level is cut and removed.

As shown in FIG. 9, when the concrete concrete 12 is placed inside the steel plate concrete ship foundation 5 with the tremie pipe 11 or the like, the steel plate concrete ship foundation 5 is sunk to the position supported by the ruler con 17 under its own weight.

Then, as shown in FIGS. 10, 16 and 17, the steel pipe pile 1
Underwater is cut near the bottom to check the strength of the bottom support ground.

Further, concrete 13 is cast around the ship foundation 5 to seal the lower area of the ship foundation 5 against the outside air, and air is injected while draining the water of the lower area of the ship foundation 5 from the outside pipe 6. Create a working space.

As shown in FIG. 11, concrete 13 'is placed in the lower region of the ship foundation 5, and as shown in FIG.
The mortar 14 is grouted in the gap between the 3'and the ship foundation 5 or in the outer pipe 6, and the backfill 15 is applied on the concrete 13 in the periphery.

After that, as shown in FIG. 13, the portion of the outer pipe 6 projecting from the basic concrete 12 is cut and removed, and the water blocking lid 16 is welded to the end to complete the basic work.

Although illustration is omitted, an upper structure is constructed on this foundation by performing a cylindrical wall construction or the like.

〔The invention's effect〕

As described above, the steel plate concrete ship foundation method for soft ground according to the present invention requires a retaining wall or the like to reach the impermeable layer in order to excavate the soft ground and construct the structure foundation at the support layer level. There is also no need to improve the bottom ground,
It is easy and quick to construct, has a high water blocking effect, and provides a highly reliable foundation.

[Brief description of drawings]

1 to 13 are vertical sectional side views of each step showing one embodiment of the steel plate concrete ship foundation method for soft ground of the present invention, and FIG. 14 is a main part showing details of the descending state of the steel plate concrete ship foundation. Fig. 15 is a vertical side view of Fig. 15, Fig. 15 is a plan view of the same as above, Fig. 16 is a vertical side view of a main part showing the submerged state of a steel plate concrete ship foundation, and Fig. 17 is a plan view of the main part. 1 …… Steel pipe pile, 2 …… Temporary gantry 3 …… Temporary mountain stopper, 4 …… Protective layer 5 …… Steel plate concrete ship foundation 5a …… Steel plate part, 6 …… Outside pipe 7 …… Descent device, 7a …… Jack 7b …… Suspending wire 8 …… Pulley, 9 …… Rebar arrangement 10 …… Concrete, 11 …… Tremy pipe 12 …… Basic concrete, 13,13 ′ …… Concrete 14 …… Mortar, 15 …… Backfilling 16: Water stop lid, 17: Ruler control

Claims (1)

[Claims] 1. A steel pipe pile is driven at appropriate intervals at a construction point of a structure, the ground is excavated by using a temporary gantry installed at the top of the steel pipe pile, and a steel plate is removed at that position after the temporary gantry is removed. The steel plate part of the concrete ship foundation was assembled, and it was suspended and supported by the descending device provided at the tip of the steel pipe pile, and then the steel plate part of the steel plate concrete ship foundation was suspended by the descending device to be launched and floated in water. The concrete is placed in the steel plate portion of the ship foundation to complete the ship foundation, the steel plate concrete is placed inside the ship foundation, and the concrete is placed so that the steel plate concrete ship foundation is sunk by its own weight. A steel plate concrete ship foundation construction method for soft ground, characterized by constructing a concrete foundation by placing concrete in the lower area of the foundation and its surroundings and then backfilling the surrounding area.