JPH09177071A - Circulation construction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the adhesion of mad cake to a hole wall by inserting a sludge recovering pipe into the vicinity of a hole bottom while injecting a stabilizing liquid from the tip of a drilling rod, and recovering the stabilizing liquid having bedrock component included therein from the bottom part of a pile pit. SOLUTION: A hole is drilled while rotating a rod bit 12, a stabilizing liquid 5 is injected from its tip, and the lower end of a sludge recovering pipe 21 is lowered from the upper surface of the rod bit 12 to a prescribed height H, the stabilizing liquid 5 having a bedrock component or slime included therein is recovered, and the drilling of a pile pit 2 is terminated. The rod bit 12 is rotated according to the lifting of a drilling rod 11, the mad cake adhered to the pile pit 2 is scraped and included into the stabilizing liquid 5. Then, the sludge recovering pipe 21 is inserted to the bottom part of the pile pit 2, the stabilizing liquid having the bedrock component included therein is sucked by a sludge recovering device 20, and fresh stabilizing liquid is supplied from a fresh stabilizing liquid tank to replace the stabilizing liquid 5 with the fresh stabilizing liquid, whereby the specific gravity and viscosity of the stabilizing liquid 5 is reduced, so that reduction in the peripheral frictional force can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a circulation construction method for constructing cast-in-place piles.

[0002]

2. Description of the Related Art (1) Normal circulation method (circulation method) (2) Reverse circulation method (reverse circulation method) is known as a conventional in-situ casting method.

The circulation method is that the stabilizing liquid is ejected from the tip of the rod bit to produce a stable ground (slime).
Is a method of pushing up to the mouth of the hole and discharging from inside the hole.

The reverse circulation method is a method of sucking slime from the tip of the bit at the same time as the stabilizing solution and discharging it from the hole while replenishing the stabilizing solution from the hole mouth.

[0005]

In the conventional circulation method, since the slime is pushed up to the hole mouth, the specific gravity / viscosity of the stabilizing solution becomes large, and the slime constantly adheres to the wall surface when passing through the wall surface of the hole. However, the water content of the mud water mixed with the ground content has decreased and the fluidity has disappeared), and the removal is troublesome.

Further, the reverse circulation method is suitable for relatively large-scale construction, the stable liquid circulation plant becomes large, and the liquid level of the stable liquid can be lowered to 5 to 6 m from the construction base surface. It cannot be constructed in a submerged stratum.

An object of the present invention is to provide an improvement of a circulation construction method which can reduce the amount of mud cake adhering to the pore wall and which does not have the drawbacks of both the above construction methods.

[0008]

According to the circulation method of the present invention, a rotary boring machine is used to drill holes with a rod bit to eject a stable liquid from the tip of the bit, and a mud recovery pipe is used to provide a predetermined height from the bottom of the hole. After that, collect the stable liquid mixed with the rock mass and pull out while rotating the rod bit after completion of drilling.After collecting the rod bit, insert the suction port of the muddy water collection pipe to near the bottom of the hole to collect muddy water / slime. It is characterized by sucking up and replenishing the stable solution new solution from the hole mouth to completely replace the mud water in the hole with new solution, and then constructing a cast-in-place pile by installing a rebar cage and placing concrete.

The predetermined height is preferably 2 to 3 m. That is, if it is 3 m or more, the effect of reducing the amount of mud cake attached to the pore wall is small, and if it is 2 m or less, it is not sucked into the suction port of the muddy water recovery pipe and cannot be effectively sucked out.

Therefore, since the slime is only floated for 2 to 3 m, compared to the conventional circulation method,
It is possible to reduce the specific gravity and viscosity of the stabilizing solution, eliminate slime that passes through the wall surface of the hole, and reduce the amount of mud cake attached to the hole wall.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (1) Preparation Step (FIG. 1) The mouthpiece 1 is set, and the hole boring machine, that is, the rotary boring machine 10 is installed so that the hole boring rod 11 having the rod bid 12 attached to the tip thereof is located at the center of the mouthpiece tube 1. Installation and muddy water recovery device 20 with muddy water recovery pipe 21
Is installed. (2) Drilling process (FIGS. 2 and 3) The rod bit 12 is rotated and lowered to drill a hole, and the stabilizing solution 5 is ejected from the tip of the bit 12 and the lower end of the muddy water recovery pipe 21 is drilled to the bottom. That is, from the upper surface of the rod bit 12 to a predetermined height H (preferably 2 to 3 m),
The stabilizing solution 5 in which the ground portion, that is, the slime is mixed is collected (FIG. 2), and the drilling of the pile hole 2 having a predetermined depth is completed (FIG. 3).

(3) Hole wall cleaning step (FIG. 4) The drilling rod 11 is pulled up, the rod bit 12 is rotated in accordance with the pulling up, and the mud cake 4 adhering to the wall surface of the pile hole 2 is scraped off to obtain the stabilizing solution 5. Mix in. Reference numeral 3 in the figure is a gravel puddle. (4) Good liquid replacement step (FIGS. 5 and 6) The muddy water recovery pipe 21 is inserted to the bottom of the pile hole 2, and the muddy water recovery device 20 sucks in the stable liquid 5 mixed with the rock mass.
The stable liquid good liquid 6 is replenished by the replenishment pipe 22 (not shown) inserted from the stable liquid good liquid tank to the bottom of the mouth pipe 1 (FIG. 5), and the stable liquid 5 and the stable liquid good liquid 6 are replaced (FIG. 6). ).

(5) Reinforcing bar installation process (FIGS. 7 and 8) The reinforcing bar cage 7 is inserted into the pile hole 2 filled with the stable liquid good liquid 6 (FIG. 7), and the installation is completed (FIG. 8). ). (6) Placing process of tremy tube with ready-mixed concrete (Figs. 9 and 1)
0) Insert the tremie pipe 8 to the center bottom of the rebar cage 7 and pour the concrete 9 from the bottom through the tremie pipe 8 into the pile hole 2 filled with the stable liquid good liquid 6 to make the stable liquid good liquid 6 (Fig. 9), the ready-mixed concrete 9 is placed up to the mouth pipe 1 to complete the construction (Fig. 10).

Next, the operation will be described.

Therefore, since the slime only floats for 2 to 3 m, the specific gravity and viscosity of the stabilizing solution 5 can be lowered and the reduction of the peripheral frictional force can be greatly suppressed as compared with the conventional circulation method.

Furthermore, slime that passes through the wall surface of the pile hole 2 can be eliminated, and the amount of mud cake attached to the hole wall can be reduced.

The mud cake 4 in FIG. 4 keeps the wall surface in a state in which the ground level of the wall surface of the stabilizing solution 5 is crushed, and prevents the wall surface from collapsing due to flooding or water leakage until the completion of drilling. Is fulfilling.

Further, according to the present method, the height difference from the installation position of the drilling machine 10 to the ground for starting drilling is within 15 m,
Construction is possible because there is no stabilizing liquid 5.

Therefore, as shown in FIG. 11, the depth h
Drilling can be started from the lower end of the deep foundation A of (15 m).

Further, as shown in FIG. 12, the height h (15
It is possible to drill a hole in the ground from above the construction pier B of m).

[0021]

As described above, according to the present invention, the following excellent effects can be obtained. (A) Since the mud water recovery pipe was inserted near the bottom of the hole, there is no slime passing through the wall surface of the hole, and the mud cake does not adhere to the hole wall. (B) Lowering the level of the stabilizing solution below the construction surface (1
5m) and the hole wall is stable even in deep holes. (C) Since the muddy water can be removed and the stabilizing solution can be separated, the concentration of the stabilizing solution can be adjusted and the one suitable for the formation can be selected.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view illustrating a preparation process.

FIG. 2 is a vertical sectional view for explaining a hole making step.

FIG. 3 is a vertical cross-sectional view showing a finished state of a hole making step.

FIG. 4 is a vertical cross-sectional view illustrating a hole wall cleaning step.

FIG. 5 is a vertical cross-sectional view illustrating a good liquid replacement step.

FIG. 6 is a vertical cross-sectional view showing the end state of the good liquid replacement step.

FIG. 7 is a vertical cross-sectional view illustrating a reinforcing bar installation process.

FIG. 8 is a vertical cross-sectional view showing the end state of the reinforcing bar installation process.

FIG. 9 is a vertical cross-sectional view for explaining a step of placing a tremy tube into a ready-mixed concrete.

FIG. 10 is a vertical cross-sectional view showing a completed state of construction.

FIG. 11 is a vertical cross-sectional view illustrating a drilled hole under a deep foundation showing an application example of the present invention.

FIG. 12 is a vertical cross-sectional view illustrating a drilling hole under a construction jetty showing another application example of the present invention.

[Explanation of symbols]

 A ... Deep foundation B ... Construction pier 1 ... Port pipe 2 ... Pile hole 3 ... Puddle 4 ... Mud cake 5 ... Stable liquid 6 ... Stable liquid good liquid 7 ... Reinforcing bar cage 8 ... Tremy tube 9 ... Ready-mixed concrete 10 ... Rotary type boring machine 11 ... Drilling rod 12 ... Rod bit 20 ... Muddy water recovery device 21 ... Muddy water recovery pipe 22 ... Supply pipe

Front page continuation (72) Inventor Masaharu Toyoshima 1-3-8 Moto-Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. Tokyo branch office (72) Inventor Masao Tsunesei 3-Hachimandai, Sakura City, Chiba 17-9

Claims (1)

[Claims] 1. A rotary boring machine is used to drill holes with a rod bit to eject a stable liquid from the tip of the bit, and a mud water recovery pipe is used to collect the stable liquid mixed with the rock mass within a predetermined height from the bottom of the drilled hole. After completion of drilling, pull out while rotating the rod bit, and after collecting the rod bit, insert the suction port of the muddy water recovery pipe to near the bottom of the muddy water.
After sucking up slime and replenishing the stabilizing solution new solution from the hole mouth to completely replace the mud in the hole with the new solution, it is characterized by installing a rebar cage and pouring concrete to construct cast-in-place piles Circulation construction method.