JPS6140813B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for constructing piles in the ground, in which the ground 3 is excavated while spouting an earth and sand solidifying agent 2 such as cement milk from the lower end of an excavation shaft 1, and the excavated earth and sand are separated from each other. The first mixed pile 4 is prepared by mixing with the solidifying agent 2.
A first step in which the lower end of the excavation shaft 1 is reached at a predetermined position by excavating while forming it in the soil, and cement, A second step of adding a soil consolidation agent such as fly ash to the required strength and kneading it again to produce the second mixed soil 7, and the first mixed pile 4.
After the lower end of the excavation shaft 1 reaches a predetermined position in the construction of the excavation shaft 1, the second mixed soil 7 produced in the second step is extruded from the lower end of the excavation shaft 1 instead of the earth and sand consolidation agent 2 in the first step, and excavation is carried out. A method for constructing piles in the ground characterized by comprising a third step of pulling up the excavation shaft 1 while filling the hole 8 and forming a pile 9 in which the excavation hole 8 is filled with the secondary mixed soil 7. This is related to.

As a conventional method of constructing piles in the ground, for example, the method disclosed in Japanese Patent Publication No. 50543/1983 is known. In this conventional example, cement milk was simply squirted out while excavating the ground, and the cement milk was mixed at the same time as the excavation to form the pile. For this reason, no matter how much the mixture is mixed underground, it is impossible to form a pile with uniform strength in the vertical direction. In addition, in this conventional example, since the cement milk is mixed with the excavated soil in the borehole, if the concentration of cement milk is high, the fluidity is low, which causes problems in mixing with the excavated soil in the borehole. As a result, the amount of cement used was small and the strength of the piles formed was weak. Another conventional example is to dump all the excavated soil to the ground and fill the excavated hole with mortar, etc., but in this case, the soil lifted to the ground must be disposed of, and filling is required separately. The drawback was that sand had to be prepared for use, which increased costs.

The present invention was invented in view of the above-mentioned conventional drawbacks, and its purpose is to be able to construct piles that are uniform in the vertical direction and have the required design strength, and to facilitate the disposal of soil that has been lifted to the ground. To provide a method for constructing piles in the ground that is less necessary, can be reused, and can reduce costs.

The present invention will be explained in detail below with reference to Examples. In the figure, reference numeral 1 denotes a hollow pipe-shaped excavation shaft, on the outer periphery of which a screw part 10 for soil lifting and stirring, or a stirring blade 11, or both the screw part 10 and the stirring blade 11 are provided. The excavation shaft 1 has a hollow pipe shape and has a bit 12 at the lower end.
A spout 1 is provided at the lower end of the excavation shaft 1.
3 is provided. In this case, the spout 13 may be provided in the bit 12 portion as in the embodiment shown. The excavation shaft 1 may be one or a plurality of shafts arranged side by side. In the case of a plurality of excavation shafts 1, the plurality of excavation shafts 1 may be arranged in a straight line laterally, or may be arranged in an arcuate manner, or may be arranged in a polygonal shape such as a triangle or a quadrangle. When a plurality of excavation shafts 1 are arranged, the upper end of each excavation shaft 1 is connected to a multi-axis device 14, and the rotation of the drive device 15 is transmitted to each excavation shaft 1 via the multi-axis device 14. 1 in the diagram
6 is a hose connected to the excavation shaft 1 in communication. Thus, the earth and sand solidifying agent supply device 20 for supplying the earth and sand solidifying agent 2 such as cement milk to the hose 16
The ground 3 is excavated while spouting the earth and sand solidifying agent 2 such as cement milk from the lower end of the excavation shaft 1, and the excavated earth and sand are mixed with the earth and sand solidifying agent 2.
Next, excavation is continued while forming mixed piles 4 in the soil.
The lower end of the excavation shaft 1 is brought to a predetermined position. The above step is referred to as the first step. On the other hand, a sieve 1 is applied to the primary mixed soil 5 lifted to the ground by the excavation shaft 1.
7 to remove the oversized gravel 6, and then to the primary mixed soil 5 from which the oversized gravel 6 was removed, a soil consolidation agent such as cement or fly ash is added to the mixer to produce the required design strength. The mixture is re-kneaded in Step 18 to produce the second mixed soil 7. This is the second step. Here, 19 in the figure is a secondary mixed soil manufacturing and supplying device, and the paste-like primary mixed soil 5
suction unit 20, sieve 17, mixer 1
8, a pump (not shown), etc. Next, in creating the first mixed pile 4, from the lower end of the excavation shaft 1, instead of the soil consolidation agent 2 in the first step, the second mixed soil 7 produced in the second step is squeezed out and filled into the excavation hole 8. While doing so, the excavation shaft 1 is pulled up and the secondary mixed soil 7 is filled into the excavated hole 8 from the bottom upwards, thereby forming the pile 9 filled with the second mixed soil 7 in the excavated hole 8. . This is the third step. Third
In the process, the hose 16 is connected to the secondary mixed soil production and supply device 19. In addition, when the secondary mixed soil 7 is squeezed out into the excavation hole 8 during the third step, the primary mixed soil 5 constituting the primary mixed pile 4 is lifted up to the ground one after another. The first mixed soil 5 is turned into a second mixed soil 7 by the second mixed soil production and supply device 19, and is again pressure-filled into the excavation hole 8 from the lower end of the excavation shaft 1. At this time, drilling shaft 1
may be pulled up while rotating, or may be pulled up without rotating. In addition, by pressurizing the secondary mixed soil 7 from below the excavation hole 8, the excavation shaft 1 and the first
The next mixed soil 5 is pushed upward.
The piles 9 having the required design strength are formed in the ground through the first, second, and third steps described above.
If necessary, a fourth step may be added after the third step in which a steel pipe or other structural material 21 is built into the pile 9 to provide the necessary bending strength and other strength. Although a single pile 9 may be constructed as described above, a retaining wall can be formed by forming the piles 9 in succession so that their ends overlap each other. In FIG. 3, when each excavation shaft 1 rotates, the multi-axis device 14 also rotates, so that the plurality of excavation shafts 1 rotate as a whole.

In the present invention, as described above, the ground is excavated while spouting an earth and sand solidifying agent such as cement milk from the lower end of the excavation shaft, and the excavated earth and sand are mixed with the earth and sand solidifying agent to perform the first mixing. The first step is to excavate while forming piles in the soil and reach the lower end of the excavation shaft at a predetermined position.The first step is to add cement, fly ash, etc. The lower end of the excavation shaft reached the predetermined position during the second step of creating the second mixed soil by adding soil consolidation agent to the required strength and kneading it again, and creating the first mixed pile. Later, from the lower end of the excavation shaft, the second mixed soil produced in the second step is extruded from the lower end of the excavation shaft, filling it into the excavation hole, and the second mixed soil is pressed out from the bottom end of the excavation shaft. The third step is to form a pile filled with mixed soil.
Ultimately, the entire length of the excavation hole in the vertical direction is filled with secondary mixed soil that has been adjusted to a predetermined strength, and the piles are constructed, making it possible to easily form piles with a predetermined strength. There are advantages and second
Since the mixed soil does not need to be stirred in the excavation hole, there is no problem even if it contains a large amount of cement and is highly concentrated, and it is possible to form piles with the required design strength. Furthermore, since the mixed soil that has been removed above the ground is reused when forming the piles, there is less need to dispose of the soil that has been removed above the ground, and sand, etc., which will be used as the material for the second mixed soil, must be prepared separately. Since it is not necessary, the cost can be significantly reduced. In addition, since the first mixed pile is formed by mixing the excavated soil and soil consolidation agent, the first mixed pile made of the first mixed soil is used during excavation and during filling with the second mixed soil. Moreover, even if the secondary mixed soil and primary mixed soil are not completely replaced and some of the primary mixed soil remains when filling with the secondary mixed soil, the primary mixed soil Since the mixed soil is a mixture of excavated soil and soil consolidation agent, the pile that is finally formed is mainly composed of the secondary mixed soil and is entirely a mixture of excavated soil and soil consolidation agent. It is something.

[Brief explanation of the drawing]

Figures 1 a, b, c, and d are schematic diagrams showing the construction sequence of the present invention, Figures 2 a, b, and c are schematic front views showing one example of an excavator used in the same manner, and the first mixed pile. A cross-sectional view at the time of forming a pile, a cross-sectional view at the time of forming a pile, and Figures 3a and 3b are a schematic front view showing another example of the same excavator as above and a cross-sectional view at the time of forming a primary mixed pile. Te, 1
is the excavation shaft, 2 is the soil consolidation agent, 3 is the ground, and 4 is the first
5 is the first mixed soil, 7 is the second mixed soil, 8 is the excavated hole, and 9 is the pile.

Claims (1)

[Claims] 1 The ground is excavated while ejecting an earth and sand consolidation agent such as cement milk from the lower end of the excavation shaft, and the excavated earth and sand are mixed with the earth and sand consolidation agent to form a primary mixed pile in the soil as the excavation progresses. , a first step of bringing the lower end of the excavation shaft to a predetermined position, and adding cement to the first mixed soil lifted to the ground by the excavation shaft.
The second step is to add soil consolidation agent such as fly ash to the required strength and re-knead it to produce the second mixed soil, and the lower end of the excavation shaft is at a predetermined position during the creation of the first mixed pile. After reaching the bottom end of the excavation shaft, the second mixed soil produced in the second step instead of the earth and sand consolidation agent in the first step is squeezed out and filled into the excavation hole, and the excavation shaft is pulled up. A method for constructing piles in the ground, comprising a third step of forming piles filled with a second mixed soil.