JPS63197718A - Construction work of in-situ pile - Google Patents

Abstract

PURPOSE:To form a concrete pile by removing slime by a method in which the tip of earth auger is sufficiently thrust into the bearing layer, cement milk is injected to the bottom of pit and sufficiently mixed to form a gel block, and the gel block is pulled up. CONSTITUTION:By using an earth auger 1, the wall of a pile pit 8 is pressed by the periphery of a drum 5 for troweling treatment, and the pit 8 thrusted through the bearing layer 18 is excavated. Cement milk 9 is injected to the bottom of the pit 8 and mixed with sand and gravel to form a gel block 10. The auger 1 is pulled up with the gel block 10, and cement mortar 11 is injected from the lower end of a rotary shaft 2 and packed into the space to form a pile. The ground of the bearing layer can thus be improved and a highly reliable pile securely joined to the ground and having a great bearing force can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for constructing site-prepared piles as foundation work for construction work.

[Conventional technology and its problems]

As is well known, such on-site piles are created by creating a hole in the ground using an excavator such as an auger screw, inserting a reinforcing cage into the hole, and then pouring concrete or mortar to form a column. It is something to do.

Such on-site construction piles are required to maintain good bearing capacity with respect to the ground, and problems arise in handling slime and bonding the lower end of the concrete to the ground.

Additionally, if the hole wall collapses during drilling, the shape of the pile will deteriorate;
Credibility becomes poor.

Various methods have been proposed for processing slime, including a method of mechanically extracting it and a method of mixing cement milk into slime to produce fill cement. It is extremely difficult to remove it, and using fill cement reduces its strength compared to regular concrete.

On the other hand, filling the inside of the drilled hole with bentonite liquid has been attempted to prevent the collapse of the hole wall, but this is not sufficient.

The purpose of the present invention is to solve the above-mentioned disadvantages of the conventional example, reliably prevent the collapse of the hole wall, and effectively remove slime to obtain concrete or mortar piles with high reliability in a few steps. The purpose of this invention is to provide a construction method for constructed piles.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention uses an earth auger with a hollow rotary shaft provided with a digging blade at the tip and a kneading drum formed in the middle. After the tip has sufficiently penetrated the supporting layer such as sand and gravel, cement milk is injected into the bottom of the hole from the rotating shaft end while expanding the diameter of the hole bottom as necessary, and the tip of the earth auger is inserted into the bottom of the hole. The support layer is improved by thoroughly kneading it with the sand and gravel in the support layer, and the cement milk is made into a gel by using a hardening agent, etc., and the gel is pulled up together with the earth auger. At the same time, mortar or cement milk is poured into the hole. The gist of this method is to inject the material into the hole, fill it, and then install a core material such as a reinforcing bar cage or steel material inside the hole.

[Effect]

According to the present invention, since the excavated soil is kneaded into the hole wall during hole excavation, the hole wall is reinforced and its collapse can be prevented. In addition, a large amount of slime generated at the bottom of the hole can be removed by placing it on the drum and cement milk gel and pulling up the earth auger. Furthermore, the cement milk injected into the bottom of the hole improves the loosening of the support layer and increases the supporting force.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIGS. 1 to 8 are cross-sectional views showing each step of a first embodiment of the method for constructing on-site piles according to the present invention. First, the earth auger 1 used in the method of the present invention will be explained.

The earth auger 1 is provided with a screw-shaped excavation blade 4 having a plurality of parallel excavation bits 3 protruding from the tip of a hollow rotary shaft 2, and a kneading drum 5 is attached at an appropriate position in the middle of the shaft 2. It is something that Furthermore, between the drums 5 of the shaft 2, radially protruding stirring blades 6 or screw blades (not shown) may be provided.

The drum 5 is formed by, for example, a 90 degree fan-shaped body attached symmetrically to the axis 2 in a plane, and is provided with a lid on the top surface having a planar shape substantially the same as the planar shape.

Using such an earth auger 1, a hole of a predetermined diameter is excavated at the planned excavation position of the pile hole 8 (FIG. 1).

In this case, the excavated soil is transported upward by a screw-shaped excavation blade 4 and crushed by an agitation blade 6 or the like to become fine. Furthermore, a portion (a considerable amount, although it varies depending on the quality of the excavated soil) is troweled onto the wall of the pile hole 8 on the outer peripheral surface of the kneading drum 5 under pressure.

Incidentally, if an appropriate amount of water is squirted from the tip of the rotary shaft 2 during excavation, the excavation can be made smoother, and the excavated soil can be turned into mud, thereby making the kneading process even easier.

Furthermore, depending on the ground, it is also possible to fill the hole 8 with a stabilizing liquid such as bentonite liquid.

As shown in FIG. Using the hollow inside, pour cement milk from the tip 9
When a predetermined amount of cement milk 9 flows into the bottom of the pile hole, the cement milk 9 is filled so as to wrap around the excavation blade 4 as shown in FIG. It is mixed with sand, gravel, etc. of the layer 18 to improve the support layer 18 that has become loose due to excavation.

Next, or in advance, an appropriate amount of cement hardening agent is injected from the two ends of the shaft. As shown in Figure 4, by moving the earth auger 1 up and down and then rotating it, the cement milk and the cement hardening agent are mixed uniformly, and the permeability of the hardening agent to the cement milk is also improved. get well.

After about 10 minutes, the cement milk is gelled by the hardening agent and becomes a cylindrical lump as shown in FIG. I will take it in. This gelled material 10 can also be formed over time without using a curing agent.

Then, as shown in FIG. 6, when the earth auger 1 is pulled up together with the mud-like cement milk gel 10, the remaining slime rides on the drum 5 and the gel 10 and is discharged out of the hole. .

At this time of pulling up, mortar or cement milk 11 is injected from the lower end of the rotating shaft 2, and the gelled material 10 rises to fill the space formed. Among these, when using mortar, it is desirable to use a curing retarder to prevent it from curing in a short time.

The cement milk gel 10 is in the form of a plug inside the pile hole 8, and when the mortar or cement milk 11 is injected, the rise of the gel 10 creates a negative pressure below the earth auger 1. It prevents the lifting load from increasing, and rather actively pushes up the gelled material 10 with its injection pressure, thus serving to assist the lifting of the earth auger 1.

Furthermore, since the hole walls are smoothed by the drum 5 as described above, the gelled material 10 can be pulled up smoothly without getting caught.

In this way, the inside of the pile hole 8 is completely filled with mortar or cement milk 11, as shown in FIG. 7. Next, as shown in FIG. By press-fitting, a pile is formed. As such a core material, in addition to the reinforcing bar cage 12, a rope material such as H-shaped steel may be used.

Next, the invention of claim 2 will be explained. The earth auger used is one in which an enlarged blade 17 is provided on the excavation blade 4 of the auger 1 described in the first embodiment.

Figures 9 to 16 show each process. Using the earth auger 1, the wire rod drum 5 is used to trowel the wall of the pile hole 8 with excavated soil to the planned excavation position of the pile hole 8 to a predetermined diameter. Drill a hole (Figure 9).

As shown in FIG. 10, once the earth auger 1 has excavated a pile hole 8 of a predetermined depth with its tip sufficiently penetrating the supporting layer 18 such as sand or gravel layer, the earth auger 1 is moved in the opposite direction. When rotated, the enlarged wings 17 expand as shown in FIG. 11, and the enlarged wings 17 form an enlarged diameter portion 8a at the bottom of the pile hole 8. Before or after that, if a predetermined amount of cement milk 9 is flowed into the bottom of the pile hole from the tip using the hollow interior of the rotating shaft 2, the cement milk 9 is mixed with the sand and gravel of the supporting layer, and as a result of excavation. Repair loose support layers.

Next, as shown in FIG. 12, the earth auger 1 is moved up and down, and further rotated, and the cement milk 9 is gelled with an appropriate amount of cement hardening agent, etc., as shown in FIG. 13, so that the whole becomes cylindrical. The ground auger 1 is pulled up together with the gelled material 10 as shown in FIG. In addition, the gelled product 1 of the cement milk 11 is formed in the expanded diameter portion 8a.
0 has a somewhat bulbous shape, but since it itself is relatively soft, there is no problem in pulling it upward.

At this time of pulling up, the gelled material 10 is pulled up by the auger 1.
Mortar or cement milk 11 is press-fitted from the shaft 2 end of the auger 1 into the space created by the rising of the auger (.

- Next, as shown in FIG. 16, by erecting a reinforcing cage 12 or a steel material as a core material into the pile hole 8, a site-made reinforced concrete pile with a large diameter end and high bearing capacity is formed.

〔Effect of the invention〕

As mentioned above, the construction of the site-prepared pile of the present invention reliably prevents the collapse of the hole wall and provides a concrete or mortar pile with a good shape, and can effectively remove slime, which reduces the reduction in bearing capacity. There is no invitation. Furthermore, since cement milk is injected into the bottom of the hole to improve the ground of the supporting layer, a highly reliable pile with a high bearing capacity and a secure connection to the ground can be obtained.

In addition, a series of processes can be performed with one earth auger, resulting in faster construction.Moreover, the piles can be built simply by injecting mortar or cement milk from the lower end at the same time as the earth auger is pulled up, and then erecting the rebar cage. Since it can be formed, the number of steps is small and construction can be streamlined.

[Brief explanation of the drawing]

Figures 1 to 8 are cross-sectional views showing each step of the construction method for on-site piles according to the present invention, and Figures 9 to 16 are cross-sectional views showing each step of other embodiments of the present invention. It is a diagram. ■...Earth auger 2...Hollow rotating shaft 3...Drilling bit 4...Drilling blade 5...Edging drum
6... Stirring blade 8... Pile hole 9... Cement milk 10... Gelled material 11... Mortar or cement milk 12... Rebar cage 17... Expanding blade 18... Support layer

Claims (2)

[Claims] (1) Using an earth auger with a hollow rotary shaft that has a drilling blade at its tip and a kneading drum formed in the middle, the drum pressurizes the wall of the pile hole while forming a hole to form a hole at the tip. After the cement has sufficiently penetrated the support layer such as sand and gravel, cement milk is injected into the bottom of the hole from the end of the rotating shaft and thoroughly mixed with the sand and gravel in the support layer using the tip of the earth auger to improve the support layer. In addition, the cement milk is made into a gel by using a hardening agent, and the gel is pulled up with an earth auger.
A construction method for on-site piles, which is characterized by simultaneously injecting mortar or cement milk into the hole to fill the hole, and then erecting a core material such as a reinforcing bar cage or steel material in the hole. (2) Using an earth auger with a hollow rotary shaft equipped with a drilling blade with enlarged wings at its tip and a kneading drum formed in the middle, the hole is formed while pressurizing and kneading the pile hole wall with the drum. After the tip has sufficiently penetrated the supporting layer such as sand and gravel, the earth auger is rotated in the opposite direction to spread the expansion wings and expand the diameter of the hole bottom. The support layer is improved by injecting and thoroughly kneading it with sand and gravel in the support layer at the tip of an earth auger, and the cement milk is made into a gel by a hardening agent, etc., and the gel is pulled up with the earth auger. A construction method for on-site piles, which is characterized by simultaneously injecting mortar or cement milk into the hole to fill the hole, and then erecting a core material such as a reinforcing bar cage or steel material in the hole.