JPS6054461B2 - Connection structure method between the head of cast-in-place concrete pile and foundation footing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure for connecting the head of a cast-in-place concrete pile to a foundation footing.

Cast-in-place concrete piles have relatively little noise and vibration;
Although it is widely used because of its many advantages, such as the large supporting capacity per rod and the ability to choose the diameter according to the load, it has had various problems in the treatment of the head of the bed.

Therefore, to explain the conventional method, a foundation pile hole is excavated in advance with an auger machine, a reinforcing bar cage is inserted into this hole,
Concrete is poured using a trimmer pipe. Then, after removing the excavation casing, burying the ground, and cutting the roots, scraping off (grinding) the poor concrete at the top end, laying gravel and waste concrete, and then reinforcing the footing. A formwork is constructed and footing concrete is placed within this formwork. By the way, the drawbacks of this conventional method are as follows.

1 Poor concrete at the head of the pillow (500-100
0wf! ft) is required, and the noise and vibrations associated with this construction may become a pollution problem and may result in complaints from neighbors.

2. Countermeasures against problems such as hole wall collapse and concrete upheaval during construction of cast-in-place concrete piles are difficult to deal with, and conventionally, the only way to deal with these problems has been to use additional driven piles.

3. Due to the slope or unevenness of the supporting ground, the length of the reinforcing bar cage is likely to be too long or too short.

4 The reinforcing bars at the head of the pillow are deformed.

5. Since the pile diameter is determined by the supporting ground conditions, the shape of the foundation footing will also be large.

6. It is difficult to take countermeasures when the top of the pile is shorter (deeper) than specified due to a measurement error.

7. It is difficult to use the joint between the pile and foundation footing as a hinge or as a fixation.

Therefore, the present invention eliminates the drawbacks of the above-mentioned prior art.
Embodiments of the present invention will be described based on the drawings.

In FIG. 1, a pile hole 1 is drilled using an earth drill at a predetermined position G where a foundation pile is to be constructed.

Therefore, reinforcing bar cage 2 is inserted into hole 1, and concrete 3 is placed at level L corresponding to the bottom of the footing using a tremie pipe.
The excavation casing 4 is then lifted up and removed. Next, as shown in FIG. 2, a ready-made connecting resistor 5 is vertically inserted into the center of the hole 1 and set.

This ready-made pile 5 is made of a steel pipe concrete pile or a steel pipe pile, and has a dowel 5a protruding from its outer periphery if necessary. A suspension lobe 6 is provided at the upper end of the ready-made pile 5, and this lobe is attached to a support bar 7 installed horizontally on the ground.
By locking this prefabricated pile is held in place in the concrete until the concrete 3 hardens. After filling the soil and cutting the roots, the mud is removed as shown in the third figure, and the tops 8 and 9 are horizontally suspended. After that, the footing is reinforced and the formwork is assembled.

Then, footing concrete 10 is poured into the formwork,
When this concrete hardens, it will be in the state shown in the fourth diagram. After that, all the steps of backfilling with soil G1 are completed as shown in Figure 5. In the foundation footing P completed according to the present invention, the upper load is entirely borne by the prefabricated connecting piles 5, and although the poor reinforcement concrete C shown in Fig. 5 is not borne by the design, it is also Effective in preventing rust, passive earth pressure, and buckling.

Next, the fifth method of handling troubles during construction according to the present invention will be explained.

FIG. 6 shows a case where the reinforcing bar cage 2 inserted into the concrete is too deep and has become short, but the ready-made connecting column 5 is lengthened accordingly.

11 is a pillar.

Fig. 7 shows a case where trouble occurs in the wall of the hole 1, but even if voids 12 and 13 occur, it is possible to prevent the hole wall from collapsing using the connecting prefabricated piles 5 and to ensure that the stress can be sufficiently supported. can.

Figure 8 shows that when a pillar 11 is installed near the site boundary line N, the axes of the pillar and the ready-made pile 5 may not match. The shaft is eccentrically aligned with the axis, and by shortening the eccentric distance between the pillar 11 and the pile 5, smooth applied transmission becomes possible.

Since the present invention has the above-mentioned structure, first of all, the lifting work can be drastically reduced, pollution caused by noise and vibration can be prevented, the construction work can be shortened, and even if troubles such as hole wall collapse occur, it is possible to make long pre-made shafts for connection. This is easy to deal with, and there is no need to worry about the length of the rebar cage being too long or too short.Furthermore, the foundation footing is smaller than before, and there is no need for waste concrete or gravel. The amount of concrete used is reduced, the concrete parts with poor backfilling are safer, and ready-made piles for connection can be mass-produced in factories.

Furthermore, it is easier than ever to freely select the members of the ready-made pile for connection and to move the pile head closer to the hinge according to changes in the load and stress on the pile head.

[Brief explanation of the drawing]

FIGS. 1 to 5 are cross-sectional views showing the construction method of the present invention step by step, and FIGS. 6 to 8 are cross-sectional views showing examples when troubles occur during construction. 1... Hole, 2... Rebar cage, 3...
... Concrete, 5 ... Ready-made piles for connection, 6.
...Suspension rope, 7...Support bar, 10...
...Footing concrete, L...Level equivalent to the bottom of the footing.

Claims (1)

[Claims] 1. Insert a reinforcing bar cage into the pile hole and drive concrete to a level equivalent to the bottom of the footing, insert a ready-made pile for connection vertically into the above-mentioned pile hole, and support this ready-made pile until the concrete hardens. After curing the concrete, removing the mud around the opening at the top of the pile hole, arranging footing reinforcement, constructing a formwork, and pouring footing concrete into this formwork. A unique structure that connects the head of a cast-in-place concrete pile to the foundation footing.