JPS59185220A - On-site bottom-expanded pile work - Google Patents

Abstract

PURPOSE:To reduce the construction cost of a pile by increasing the bearing force of the pile by a method in which a pit is excavated and a drill bit is pushed out toward the right angled direction to the axis of the excavated pit in a given position to form a pit having large diameter. CONSTITUTION:Under the condition that the hole expanding cases 17 of a head 10 remain unchanged on the original positions, drill bits 18 are rotated to excavate the columnar portion A1 of a pit A. The hole expanding cases 17 of the head 10 are turned and the drill bits are pushed out toward the right angled direction to the pit axis and rotated to excavate a bell-shaped expanded bottom portion A2. Slime is treated, concrete is placed, and on-site pile having an expanded diameter portion is formed. The bearing force of the pile can thus be greatly increased, construction cost can be also greatly reduced, and excavation can be made with exact shape and dimension in a given position.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cast-in-place expansion pile method in which the lower end of an excavated hole or any arbitrary position is expanded using an excavator equipped with a triaxial bit and concrete is poured into the hole.

BACKGROUND ART Recently, as a countermeasure against vibration and noise pollution during pile driving, a cast-in-place pile method has been widely adopted, in which support piles or earth anchors are constructed by pouring concrete into an excavated hole formed by an excavator. When using this construction method, the construction cost depends on the amount of excavated soil, the amount of concrete placed, and the amount of soil removed and muddy water treated, and the investment and operating costs for temporary construction equipment such as muddy water tanks and settling basins are not small.

Therefore, an object of the present invention is to provide a cast-in-place expanded-bottom pile construction method that is highly versatile and can be used on any type of ground, while increasing the supporting capacity of piles and reducing construction costs.

According to the present invention, a borehole is drilled, a drill bit is pushed out in a direction perpendicular to the axis of the borehole at a predetermined position, a large-diameter borehole is drilled, the slime is treated, and concrete is poured. , to create a cast-in-place pile with an enlarged portion of the borehole diameter.

By the method described above, the lower end of the excavated hole or any arbitrary position can be expanded by the required amount.

As a result, the bearing capacity can be significantly increased, and compared to vertical piles with the same bearing capacity, the amount of excavation, concrete placement, soil removal, and muddy water treatment can be significantly reduced, leading to a reduction in construction time. In addition to shortening the time, it is possible to significantly reduce construction costs, and it also has the advantage of being able to excavate even rock and gravel layers, and accurately excavating at a predetermined location and shape.

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 to 3.

FIG. 1 is an overall explanatory diagram of an excavator implemented in the present invention. The excavator inserted into the excavation hole A includes a head 10 whose details will be described later, a reverse rod 1 that suspends the head 10 via a short pipe 11, and a stabilizer 2 that guides and supports the reverse rod 1 into the excavation hole A. , a reaction force pedestal 3 that supports the reaction force of the reverse rod 1, and a swivel 4 that is inserted into the reverse rod 1 and supports the reverse slot 1.
A crane 5 is used to hang a Kelly rod, a rod drilling bit, an underwater mode for driving, a gear, etc. from a hanging fitting provided at the upper end of the rod. It is roughly composed of a cable 7 that supplies electric power and hydraulic pressure to the head 10, and a cable reel 8 around which the cable 7 is wound. Note that the Kelly rod 6 is connected to a suction pump 9.

FIG. 2 shows details of the head 10. The head 10 includes an underwater mode 13 equipped with an outlet box 12, a reducer 14 and a drive shaft 15 that reduce and transmit the power of the underwater mode 13, and a drive shaft 15. A driven revolution case 16, three hole expansion cases 17-17 rotatably supported by the revolution case 16 via a support shaft 17A, and drill bits 18-18 attached to the hole expansion cases 17-17, respectively. 18, stoppers 19 to 19 that lock the hole expansion case and set the hole diameter during hole expansion;
It consists of a hole expansion brake 20 that adjusts the hole expansion diameter.

A hole expansion brake device 20, a reverse suction port 21 that sucks muddy discharged soil, a reverse bit 22 that excavates the vicinity of the suction port 21, a displacement meter 23 that also serves as a depth gauge, and a valve that adjusts the position of the adjustable guide. It consists of a box (electromagnetic valve) 24, a bellofram cylinder 25 for balancing cylinder oil pressure and mud water pressure, a guide 26 and an adjustable guide 27 for guiding and supporting the head 10 into the drilling hole A, and a drilling control device (not shown). ing.

This head 10 has a support shaft 17A that supports the expanded hole cases 17 to 17.
Drill bit 18 by pivoting outward about
The rotational position of ~18 is pushed out in a direction perpendicular to the hole axis of the borehole A, thereby enlarging the borehole A.

Excavation of the cylindrical part by this head 10 is carried out by independently rotating the three drill bits 18 to 18, and
The rotation of each bit and the revolution of the revolution case 16 are made in the same direction, and the whole bit is rotated together, and when the bottom end of the drilling hole A or an arbitrary position is widened or enlarged in a bell shape, three Drilling is performed by gradually expanding the two drill bits 18 to 18 laterally in a direction perpendicular to the hole axis.

The excavated earth and sand are discharged together with muddy water from the reverse suction port 21 by the suction pump 9.

Next, an embodiment of the present invention will be described with reference to FIG.

(a) ■Drive the stand pipe 28 into the excavated area.

(b) ■Pi! A shovel 29 is used to excavate in advance only the amount by which the Nistand pipe 28 is driven.

(C) Process: While the hole expansion cases 17 to 17 of the head 10 remain in their original positions, the drill bits 18 to 18 are rotated and revolved to drill the cylindrical portion A1 of the drilling hole A.

(d) ■Process: Expanded hole case 17 to 17 of head 10
The drill bits 18 to 18 are pushed out in a direction perpendicular to the hole axis, rotated and revolved, and the bell-shaped enlarged bottom part A2 is rotated.
excavate.

(l Process: The bottom roughness of the expanded bottom part A2 and (here -
Please enter a description of the next slime process) - Next process the slime process.

(f) Step: The head 10 is pulled out and the condition of the hole wall of the drilled hole A is measured using the measuring device 3o.

((1) Lower and insert the reinforcing bar cage 31.

(h) Step: Insert the tremie pipe 32 for concrete pouring inspection (please consider).

(1) Apply secondary slime treatment to stains caused by work on the second stage of the process.

(j > Process: The tremie pipe 31 is moved upward while concrete 33 is being poured.

(k) Process After pouring concrete 33 up to the top of the stand pipe 28, it is backfilled with a bucket 34.

i) Pull out the process Nistand pipe 28.

As described above, according to the present invention, a triaxial bit that can rotate and revolve is extruded in a direction perpendicular to the borehole axis to expand the borehole diameter, which greatly increases the supporting capacity of the pile and significantly reduces construction costs. It has the following advantages over conventional construction methods.

(i) It is possible to excavate a dense sand layer, gravel layer, and dotan layer with an N value of 50 or more, penetrate through the intermediate layer, and ensure a reliable penetration depth into the supporting layer ground.

(ii) Since the bottom-expanding excavation status can be grasped by a control device installed on the ground, highly reliable bottom-expanding holes can be constructed.

(iii > Adjustable guide 2 of head 10
7, it is possible to correct the bend in the drilling hole A, which is 1/1 of the conventional
It is possible to construct piles with high vertical accuracy of 11500 to 1/2000 compared to 00 to 1/3oO.

(:V) Three drill pits 1 to 18 to 1 of head 10
8 also revolves in the rotation direction □, so the digging force is large,
Furthermore, since the cutting edge of the bit draws a trochoidal trajectory, slime can be efficiently collected by the reverse suction port 21.

[Brief explanation of the drawing]

Figure 1 is an overall explanatory diagram of an excavator used in an embodiment of the present invention, Figure 2 is an enlarged side view of its head, and Figure 3 (a).
~(ff> is a detailed process diagram of the construction method.

Claims (1)

[Claims] In the cast-in-place pile construction method, a support pile or base anchor is constructed by pouring concrete into a hole formed with a drill bit of an excavator, and a hole is excavated at a predetermined position, and the drill bit is used to drill the hole. The feature is that a large-diameter borehole is excavated by extrusion in a direction perpendicular to the borehole axis, and then the slime is treated and concrete is poured, thereby creating a cast-in-place pile with an enlarged part of the borehole diameter. Cast-in-place expansion pile method.