JPS6147929B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention comprises a step of drilling a pile driving hole in the presence of a bentonite solution, a step of inserting and installing a reinforcing bar cage into the drill hole, and a step of inserting and installing a tremie pipe into the drill hole. The present invention relates to a method for driving cast-in-place piles, which includes a step of inserting them into the pile and pouring concrete therethrough.

Conventionally, this type of construction method has had the following problems.

That is, since a pile driving hole is excavated while injecting a large amount of a stabilizing liquid such as a bentonite solution, a considerable thickness of a precipitated layer called slime is generated at the bottom of the excavated hole. Therefore, before installing a reinforcing bar cage or pouring concrete, most of the slime is removed using the bottom-roughing bucket method, air lift method, jet method, jet lift method, etc. From this slime removal, the actual concrete is poured. In general,
It takes 30 to 40 minutes, and during this time slime settles again at the bottom of the borehole, and eventually
A 30cm to 40cm layer of slime inevitably remains.

In addition, since the hole is usually excavated mechanically using an auger or the like, the bottom of the hole is considerably weakened by the tip of the auger.

In this way, the bottom of the borehole becomes extremely soft due to the combination of slime precipitation and softening caused by mechanical excavation. Therefore, even if the specified slime treatment is carried out, after pouring concrete and constructing piles, the piles may sink, and especially if the piles settle unevenly, it may have a negative impact on the superstructure. There was a high possibility that this would cause

The present invention has been made in view of the above-mentioned conventional situation, and its purpose is to provide a completely new cast-in-place pile that can strengthen the soft layer at the bottom of an excavation hole and prevent the pile from sinking. The purpose is to provide a pouring method.

First, one embodiment of the present invention will be described below with reference to the drawings.

That is, the driving of cast-in-place piles according to the construction method of the present invention is performed in the following steps.

(i) First, as shown in Figure 1A, while injecting a stabilizing liquid (hole wall protection liquid) such as bentonite solution into a predetermined position, use an auger (not shown) etc. to drill the pile driving hole. 1 is mechanically excavated and left for a certain period of time until slime 2 is precipitated at the bottom of the excavated hole 1.

(ii) Next, as shown in FIG. 1B, the precipitated slime 2 is removed by, for example, the bucket method.

(iii) Then, as shown in Fig. 1C, the reinforcing bar cage 3 is inserted and installed.

(iv) Next, an inverted conical metal lid 4 as shown in FIG. 2 is attached to the tip of the tremie tube 5, and as shown in FIG.
is inserted until the tip of the lid 4 passes through the precipitated slime 2 again and reaches the bottom of the excavated hole 1.

(v) In this state, as shown in FIG. ,
The lid body 4 is firmly pushed into the weak part at the center of the bottom of the excavation hole 1.

(vi) Next, as shown in FIG. 5 and the lid body 4 are separated.

(vii) Then, as shown in Figure 1G, the tremie tube 5
Concrete C is continuously poured while gradually pulling up the tremie pipe 5 so that the lower end of the pipe is always located below the upper surface of the poured concrete C.

(vii) Finally, as shown in Figure 1C, the excess concrete C' is removed and the ground G is leveled.

In addition, in the above embodiment, the tremie tube 5
Although a metal inverted cone-shaped lid body 4 is used as the lid body 4 attached to the tip, it may be made of ceramic, hard plastic, or other relatively hard materials. It is not limited to the shape of an inverted cone, but also the shape of an inverted pyramid, or the shape of an inverted pyramid as a whole with a large number of sharp protrusions 4a attached to the outer surface as shown in Fig. 3 A and B. May be used.

Further, as shown in FIG. 4, a protruding piece 4c protruding in the diametrical direction is provided on the outer surface of the cylinder shaft 4b fixed to the upper surface of the inverted conical lid 4, while the open end of the tremie tube 5 The tremie tube 5 is provided with a notch 5a on its edge that fits in the projection piece 4c in the vertical direction.
By rotating the lid body 4 around its axis,
A spiral blade 4d is provided on the inverted conical lower surface of the lid 4, and the tremie tube 5 is rotated and lowered to screw the lid 4 into the bottom of the excavation hole. You can do it like this.

In summary, the method for driving cast-in-place piles according to the present invention includes the steps of excavating a pile driving hole in the presence of muddy water, inserting a reinforcing bar cage into the excavated hole, and inserting a tremie pipe into the excavated hole. In a construction method that includes a step of inserting a device into the hole and pouring concrete through the device, when the tremie pipe is installed in the excavated hole and concrete is poured, an inverted conical cap is attached to the lower end of the tremie pipe. The tremie tube is inserted into the excavation hole with the inverted conical lid reaching the bottom of the excavation hole, and in this state, the tremie tube is filled with concrete, and the tremie tube and the concrete are removed. The entire weight of the tremie tube is applied to the tip of the inverted conical lid, and then the tremie tube is slightly pulled up to separate the tremie tube and the inverted conical lid by the weight of the concrete. The feature is that concrete is placed continuously while being salvaged.

The functions and effects achieved by the above characteristic configuration are as follows.

That is, as shown in Figure 1 E and F above, the inverted cone-shaped lid attached to the tip of the tremie pipe is firmly attached to the bottom of the excavation hole by the total weight of the tremie pipe and the concrete inside it. In addition, concrete can be reliably placed inside and near the lid, which performs the same function as cracked stone and sufficiently strengthens the soft layer at the bottom of the borehole. Since concrete can be placed reliably at the bottom of the excavation hole, unlike conventional methods, a slime layer does not remain between the bottom of the hole and the lower end of the poured concrete pile, which prevents subsequent pile settlement. This has made it possible to reliably prevent the negative effects on the superstructure due to uneven settlement of piles and piles.

[Brief explanation of the drawing]

Figures 1 to 3 show explanatory diagrams of an embodiment of the construction method of the present invention, Figures 1 to 1 are schematic sectional views showing the steps of the construction method, Figure 2 is a perspective view of the main parts, and Figure 3 A and B are sectional views of main parts of different embodiments, respectively. Fourth
The figure is a perspective view of main parts showing another embodiment. 1... Hole for pile driving, 2... Slime, 3... Rebar cage, 4... Inverted conical lid, 5... Tremy tube, C
……concrete.

Claims (1)

[Claims] 1 Step of drilling a hole for pile driving in the presence of muddy water, step of inserting and installing a reinforcing bar cage into the hole, and inserting and installing a tremie pipe into the hole and pouring concrete through it. In the method of driving cast-in-place piles, which includes a step in which the tremie pipe is installed in an excavated hole and concrete is poured, an inverted conical lid is attached to the lower tip of the tremie pipe, and the inverted conical The tremie pipe is inserted into the excavation hole so that the shaped lid reaches the bottom of the excavation hole, and in this state, the tremie pipe is filled with concrete, and the total weight of the tremie pipe and concrete is transferred to the tip of the inverted cone. After that, the tremie tube is pulled up slightly to separate the tremie tube and the inverted conical lid body by the weight of the concrete, and thereafter, concrete is poured continuously while gradually pulling up the tremie tube. A method for driving cast-in-place piles.