JPH0567733B2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention is directed to the so-called reverse (circulation)
Regarding the method of erecting hollow piles (construction method), in particular, by returning the excavated sand (mud and sand) generated by excavation to the pile driving hole and solidifying it, it is easy to remove the excavated sand that was treated as industrial waste and a nuisance. and can be processed effectively.

Prior Art Japanese Patent Publication No. 1988-88720 is known as a method for erecting hollow piles.

This method involves drilling a vertical hole in the ground at the tip of a hollow pile, injecting cement milk into the vertical hole, mixing it with excavated soil, and producing soil cement in the vertical hole. Apply some of it almost smoothly to the wall of the vertical hole, intermittent it,
Then, the hollow pile is pushed into the vertical hole whose wall surface is coated with soil cement.

After pushing the hollow pile to a predetermined depth, the drilling rod is removed from inside the hollow pile, a tremie pipe is inserted in its place, and concrete for root protection is poured into the hollow pile from the tremie pipe, The bottom of the hollow pile is fixed with the concrete used for root protection.

Problems to be Solved by the Invention By the way, in the conventional method of erecting piles, concrete for root protection is injected into the soil cement inside the hollow pile, and the concrete for root protection is injected into the soil cement inside the hollow pile. The concrete used for the foundation was fixed at the bottom of the hollow pile by allowing the concrete to collect at the bottom of the vertical hole, and this caused the following problems.

(1) The specific gravity of concrete for root protection must be greater than the specific gravity of mail cement.

(2) Even if the specific gravity of the concrete for root protection is increased, it takes a long time for the concrete for root protection to accumulate at the bottom of the vertical hole by pushing up the mail cement, or to settle.

The present invention solves the above conventional problems and eliminates the need to consider the specific gravity of soil cement and concrete for root protection, and also eliminates the need to wait for concrete for root protection to settle. It was made with the purpose of providing.

Means for Solving the Problems The present invention provides a method for erecting hollow piles, in which a drill pit is attached to the tip of a drill pipe, the drill pit is lowered into a site to be excavated filled with muddy water, and the drill pit is rotated to excavate earth and sand. At the same time, there is a first step of discharging the excavated earth and sand to form a pile driving hole, and pouring concrete for foundation hardening at the bottom of the pile driving hole, and forming a hollow hole that will become a pile inserted into the pile driving hole. The second step is to bury the lower end of the pile (steel pipe) in the concrete for root reinforcement, and the second step is to mix cement with the earth and sand taken out when excavating the pile driving hole and return it to the hollow pile. It consisted of three steps and.

Function The supporting capacity of the lower end of the hollow pile inserted into the pile driving hole is increased by the concrete for root reinforcement, and it is maintained in a firm and upright state.

Furthermore, the excavated sand injected into the hollow pile is hardened with cement and becomes integrated with the hollow pile, reinforcing the hollow pile from the inside.

EXAMPLE Next, a method for erecting a hollow pile (concrete filling solidification pile construction method with steel pipe foundation hardening) of the present invention will be explained with reference to FIGS. 1 to 10.

First, as shown in FIG.
Build in. Rooting length l of stand pipe 12
be below the groundwater level, and ensure that the height h from the groundwater level to the mud water level in the standpipe 12 is 2 m or more.

A rotary table 13 is attached to the bevel 11 so as to be movable in the horizontal and vertical directions, and a hollow drill pipe 14 is attached to the rotary table 13. When the rotary table 13 is rotated, the drill pipe 1
4 is designed to rise and fall while rotating. The upper end of the drill pipe 14 is connected to the Kelly bar 1.
5, and on the lower end side there is a stabilizer 16 and a triangular wing drill bit 1 with weight.
7 is attached, and when the rotary table 13 is rotated in the forward direction, the drill pipe 14, the stabilizer 16 and the drill bit 17 attached to the tip thereof rotate and descend, excavating the earth and sand to a predetermined depth. A piling hole 18 is formed.
In this case, the drill pipe 14 is connected according to the depth of the piling hole 18. Further, the diameter of the pile driving hole 18 is set to be approximately 100 mm larger than the diameter of the steel pipe 19 that will become the hollow pile. The excavated sand generated during excavation is sucked up together with water by a pump (not shown) and discharged into a water tank (not shown).
8 and excavation is performed while circulating water, and when the excavation is completed, the drill pipe 14 and the like are removed.

After the drill pipe 14 and the like are removed from the piling hole 18, a steel pipe 19 that will become a stake is inserted into the piling hole 18 as shown in FIG. As described above, this steel pipe 19 is formed to have a diameter smaller than the diameter of the piling hole 18 by about 100 mm, and is also formed to be slightly shorter than the depth of the piling hole 18. At its upper end, there is a so-called steel pipe rod 20 having the same diameter as the steel pipe 19.
are removably attached by bolts 21...21 (see Figures 7 and 8), and by supporting the steel pipe 20 with a support member 22 provided on the bevel 11, the steel pipe 19 has its lower end. It is suspended in the pile driving hole 18 with its axis being kept in the opposite direction while being lifted up from the bottom surface of the pile driving hole 18 by a predetermined height.

After hanging the steel pipe 19 into the piling hole 18, the rotary table 1 is placed as shown in Fig. 3.
A tremie pipe 23 is attached to the tremie pipe 23, a three-wing expanded wing 24 is attached to the lower end of the tremie pipe 23, and the expanded wing 24 is lowered through the steel pipe 19 to the bottom of the piling hole 18.

The expanded wing 24 is attached to a fixed pipe 25 at the lower end of the tremie pipe 23, as shown in FIGS.
At the same time, a slide pipe 26 that extends and contracts in the length direction of the tremie pipe 23 is slidably fitted into the fixed pipe 25 (spline connection).
has been done.

A lower wing piece 27 is attached to the lower end of the slide pipe 26.
One end is supported by a pivot 28, and the lower wing piece 2
An upper wing piece 30 is pivotally supported at the other end of 7 by a pivot 29,
It is formed by pivoting the other end of the upper wing piece 30 to the fixed pipe 25 with a pivot 31.

When the expanded wing 24 is suspended, the slide pipe 26 descends under its own weight with respect to the fixed pipe 25, as shown in FIG. It is designed so that it can be stretched out and passed through the steel pipe 19.
Then, when the tremie pipe 23 to the fixed pipe 25 are further lowered with the lower wing piece 27 in contact with the bottom surface of the piling hole 18, the slide pipe 26 is more fitted into the fixed pipe 25, as shown in FIG. As shown in FIG. 2, the lower wing piece 27 is bent at a predetermined inclination angle α with respect to a horizontal plane at a pivot 28. Therefore, in this state, the tremie pipe 23
And by rotating the expansion wing 24, the pile driving hole 1
The bottom surface of No. 8 will be leveled into a bowl shape with a predetermined angle of inclination.

Then, after rotating the expanded wing 24 and disposing of the slime on the bottom of the piling hole 18, the fourth
As shown in the figure, a part of the upper part of the tremie pipe 23 is removed, a so-called funnel 32 is attached to the upper end of the tremie pipe 23, and concrete 33 for foundation hardening is passed through the funnel 32 to the bottom of the piling hole 18. Then, the expansion wing 24 is slightly lifted, the steel pipe 19 is lowered, and the lower end of the steel pipe 19 is buried in concrete 33 for foundation consolidation.

Then, once the concrete 33 for foundation hardening has hardened to some extent, the tremie pipe 23 and the pressure feeding pipe 3 connected to the upper end of the tremie pipe 23 are moved.
Cement (soil-based improved mortar) is poured into the steel pipe 19 through the steel pipe 4, and excavated earth and sand are directly poured into the steel pipe 19 through the delivery hose 35 from the top of the steel pipe 19.
Inject into 9. The injected sand gradually settles,
These cement and excavated sand are removed from the expansion wing 24.
Stirred with Cement and waste sand are injected to the upper end of the steel pipe 19, and the inside of the steel pipe 19 is filled with a mixture of cement and waste sand. Once the inside of the steel pipe is filled, the outer circumference of the steel pipe 19 and the inner circumference of the piling hole 18 are connected. Fill the gap with a mixture of cement and excavated sand.

After that, the tremie pipe 23 is removed, the turret 11 and the stand pipe 12 are removed, and the steel pipe holder 20 is removed from the upper end of the steel pipe 19. As shown in FIG. 33, and the inner and outer peripheries of the steel pipe 19 are firmly hardened with cement and excavated sand, resulting in a steel pipe pile.

Effects of the Invention The hollow pile erecting method of the present invention has the following effects.

(1) Since the excavated sand is returned to the hollow pile (steel pipe), it becomes easier to dispose of the excavated sand, and the overall cost of the cast-in-place method can be reduced accordingly.

(2) Social problems such as the construction of sludge treatment plants can be reduced.

(3) Since the excavated sand solidifies inside the hollow pile, the hollow pile becomes reinforced from within, increasing the mechanical strength of the pile.

(4) Since the excavated earth and sand are discharged from the piling hole along with water, the presence of the water makes it easy to separate the earth and sand into dirt, sand, pebbles, etc., and the effective use of the soil, sand, pebbles, etc. It becomes possible.

[Brief explanation of the drawing]

Figures 1 to 6 are explanatory diagrams showing the work steps of the construction method of the present invention, Figure 7 is a plan view of the joint of the steel pipes, Figure 8 is a side view of the same, and Figure 9 is the reduced diameter of the expanded wing. A side view of the state, FIG. 10 is a side view of the diameter expanded state. 13... Rotary table, 14... Drill pipe, 17... Drill bit, 18... Piling hole, 19... Steel pipe (hollow pile), 33... Concrete for root protection.

Claims (1)

[Claims] 1. A drill pit is attached to the tip of a drill pipe, and the drill pit is lowered into an excavated trench filled with muddy water. The drill pit is rotated to excavate earth and sand, and the excavated earth and sand are discharged to form a pile. The first step is to form a driving hole, and at the same time, pour concrete for foundation protection at the bottom of the pile driving hole, and place the lower end of the steel pipe that will become a hollow pile inserted into the pile driving hole into the concrete for foundation protection. A method for erecting hollow piles comprising: a second step of burying the pile in the steel pipe; and a third step of mixing cement with the earth and sand taken out when excavating the pile driving hole and returning the mixture to the steel pipe.