JPS6327618A - Setting work of concrete pile by preboring - Google Patents

Abstract

PURPOSE:To exactly fix a concrete pile with lesser noise by reducing the number of striking times by a method in which excavation is made while injecting cement milk from slightly before a given depth of a pit, and rotation and pressure are applied in the latter period of pile penetration. CONSTITUTION:A pile pit 3 is excavated in the ground 1 where a foundation pile is to be set, and a precast concrete pile 7 is penetrated into the pit 3 for setting. During the excavation period, excavation is made while injecting cement milk through the tip of an excavating head from slightly before a given depth of the pit 3 to complete the pile pit 3. In the latter period of penetrating the pile 7, the pile 7 is turned and penetrated while applying a given pressure to the pile 7, and the head of the pile 7 is slightly struck and set on the bearing ground. The concrete pile 7 can thus be exactly fix to the bearing ground by a comparatively smaller number of strikes.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a construction method for installing foundation piles by pre-boring, and belongs to the industrial field related to foundation pile installation.

(Prior Art) Various methods have been proposed as conventional foundation pile construction methods.

For example, there is a known method in which a stake hole is drilled in advance, a ready-made stake is inserted into the hole, and when the stake reaches the bottom of the hole, the hard head is hit with a hammer.

In another example, the diameter near the bottom of the pile hole is made slightly larger, cement milk is injected into the slope, and the cement milk is stirred and mixed with the remaining earth and sand in the pile hole, and the pile is poured into the expanded bottom part. There is a construction method in which the lower end of the peg is inserted to support the peg as the mixture hardens.

(Problems to be Solved by the Invention) Among the conventional construction methods mentioned above, in the Monken hammering method, Monken hammering must be performed quite a number of times in order to make the tip of the pile reach the bottom of the pile hole and further obtain a predetermined supporting force. Therefore, there is a risk of generating noise pollution, and there is a restriction on the number of times of impact, which may lead to insufficient anchoring of the pile.

On the other hand, the expanded root trapping method requires multiple layers of cement milk, which not only puts pressure on economic efficiency, but also has the problem of unstable supporting capacity.

(Means for Solving the Problems) This invention performs a press-fitting operation while rotating the pile at the end of the pile insertion work, and performs a swinging strike after the lower end of the pile reaches the bottom of the pile, so the number of swinging strikes is significantly reduced. In addition to being able to do so, it also ensured support.

That is, this invention provides a construction method in which a difficult hole is excavated at a site where a foundation pile is to be installed, and a ready-made concrete pile is inserted and installed into the hole. After injecting more cement milk, excavation is completed, and after the hole is completed, a pile is inserted, and in the latter stages of the pile insertion, the pile is rotated and the pile head is press-fitted by applying a predetermined pressure. It is characterized by installing a peg on the supporting ground. The cement milk injection start depth in this invention is
The height of the pile shall be several meters before reaching the bottom of the planned pile, and the pressure applied to the head of the pile shall be approximately 20 to 40 tons. Also, the supporting ground is N
It refers to a layer in which several meters of continuous layers have a value of 50 or more.

(Operation of the Invention) As described above, according to the present invention, since cement milk is injected at the final stage of the pile hole excavation, collapse of the excavated pile hole can be prevented even in sand or other weak ground. I can do it.

Also, after press-fitting the stake, a light tap is performed, so the lower end of the stake is securely supported at the bottom of the hole.

(Example) Next, an example of the present invention will be described based on the drawings. First, go to the difficult conger eel ground 1 as shown in Figure 1, and use the polling machine 13.
and hold the auger rod 2 vertically. Next, the auger rod 2 is rotated to start drilling the borehole 3. The auger rod 2 includes a drum 4 and a stirring piece 5.
Since the soil is fixed at predetermined intervals, the soil excavated by the auger 6 is hardly taken out to the outside world (it is crushed by the stirring piece 5 and kneaded into the pile hole 3 by the drum 4.

In this way, the drill hole 3 is 5 m above the planned drill hole bottom 3a.
When this point is reached (FIG. 3), excavation continues while cement milk is discharged from the tip of the auger 6. The excavated soil and cement milk mix and remain at the bottom of the hole, preventing the bottom of the hole from collapsing while digging the hole to a predetermined depth. Next, the auger rod 2 is pulled up, and then a ready-made concrete pile 7 is suspended and inserted by its own weight. (For example, 20m to 50m) when the hole is deep.
, a number of ready-made concrete piles 7.7a corresponding to the depth of the pile holes are successively inserted.

When the lower end of the lower concrete pile 7 reaches the point where it plunges into the mixture of excavated soil and cement milk (approximately 5 m from the bottom of the pile hole) (or when it becomes difficult to insert its own weight, Fig. 5) Then, while applying downward pressure to the upper end of the concrete pile, the pile is further pressed while rotating, and the lower end of the concrete pile 7 reaches the bottom of the pile hole (Fig. 6). Next, tap the concrete head with Monken 8 and the concrete pile will be installed.

The pressing force in the above can be applied, for example, by attaching the sheave 12 to the housing 11 of the drive device, which is fixed via the transmission shaft 10 to the cap 9 fitted to the upper end of the concrete pile 7, and by connecting the sheave 14 of the polling machine 13 and the winder 15. Grant via. For example, by winding the wire 16,
By bringing the sheave 12.14 closer, the tensile force of the wire is converted into a downward pressure, making it possible to pressurize the concrete pile 7.7a in the direction of arrow 17 in FIG.

Furthermore, the blow by Monken 8 is caused by the condition shown in Figure 7.
Strike Monken 8 up and down. Excavation of the stake hole 3 or insertion of the stake in the embodiment is not necessarily limited to the embodiment, and conventionally known techniques can be used.

(Effect of the invention) In this invention, at the final stage of inserting a concrete pile, the head of the concrete pile is pressurized and the pile is press-fitted, and when the lower end of the concrete pile reaches the bottom of the pile hole, it is lightly struck with a Monken. The relatively small number of blows has the effect of reliably anchoring the concrete pile to the supporting ground.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the poling machine set on a fixed ground for stakes, Figure 2 is a diagram showing the drilling of a stake hole in the middle of the implementation of this invention, and Figure 3 is a diagram of the drilling of a stake hole in progress and the cement milk injection has begun. Figure 4 is the same diagram when the pile hole is finished being excavated, Figure 5 is the same diagram when the concrete pile has been inserted to the starting position, Figure 6 is the same diagram when the concrete pile is finished being press-fitted, and Figure 7 is the same diagram when the pile head is inserted. Figure 8 is a diagram when hitting with a Monken, and Figure 8 is a diagram when the stake is finished. 1... Conger eel fixed place 2... Auger rod 3
... Pier 6 ... Δ-Gar 7 ... Concrete pile 8 ... Monken 13 ... Polling machine

Claims (1)

[Scope of Claims] 1. In a construction method in which a difficult hole is excavated at a site where foundation piles are planned to be installed, and a ready-made concrete pile is inserted and installed into this pile hole, when excavating the pile hole, the excavation head is inserted from slightly before the predetermined depth of the pile hole. Cement milk is injected from the tip of the hole while drilling, and after the hole is completed, a peg is inserted.In the latter stage of inserting the peg, the peg is rotated and press-fitted into the peg by applying a predetermined pressure. Concrete pile installation method 2 by pre-boring characterized by lightly tapping the pile head and installing the pile on the supporting ground Claim No. Method 3 for installing concrete piles by pre-boring according to claim 1. Claim 1: The pressure applied to the pile head is 20 tons to 40 tons.
4. Method for installing concrete piles by pre-boring as described in Claim 4. The method for installing concrete piles by pre-boring as described in Claim 1, wherein the supporting ground is a continuous layer of several meters with an N value of 50 or more.