JPS6140815B2 - - 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 a 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 earth are mixed together. First mixed soil 5 by mixing with consolidation 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 and sand as an aggregate to obtain the required strength and kneading this again to produce a second mixed soil 7 containing aggregate; and a first mixing step. After the lower end of the excavation shaft 1 reaches a predetermined position in the preparation of the soil 5, the second mixed soil 7 containing aggregate is produced in the second step from the lower end of the excavation shaft 1 in place of the earth and sand consolidation agent 2 in the first step. The method is characterized by comprising a third step of pulling up the excavation shaft 1 while pressing out and filling the excavation hole 8, and forming a pile 9 in which the excavation hole 8 is filled with the secondary mixed soil 7 containing aggregate. This relates to the method of constructing piles into the ground.

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, when the excavated soil is made of clay, there is no aggregate even if it is mixed with cement milk, so the strength of the pile formed is weak.

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 or stirring blades 11 or both the screw part 10 and stirring blades 11 are provided for lifting and stirring soil.
The excavation shaft 1 is shaped like a hollow pipe and has a bit 12 at its lower end, and a spout 13 at its lower end. In this case, the spout 13 may be provided in the bit 12 portion as in the embodiment shown. Drilling shaft 1
may be one or a plurality of lines. 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 the excavation shaft 1 is connected to the multi-axis device 14,
The rotation of the drive device 15 is transmitted to each excavation shaft 1 via the multi-axis device 14. In the figure, 16 is a hose connected to the excavation shaft 1 in communication. However, the hose 16 is connected to a soil solidifying agent 2 such as cement milk.
The excavated soil and the soil solidifying agent 2 are connected to the earth and sand solidifying agent supply device 20 for supplying the earth and sand while excavating the ground 3 while spouting the earth and sand solidifying agent 2 such as cement milk from the lower end of the excavation shaft. is mixed to form a primary mixed soil 5 in the soil as the excavation progresses until the lower end of the excavation shaft 1 reaches a predetermined position. The above step is referred to as the first step. On the other hand, the primary mixed soil 5 lifted to the ground by the excavation of the excavation shaft 1 is passed through a sieve 17 to remove gravel with large grains, and then cement is added to the primary mixed soil 5 from which the gravel with large grains has been removed. A soil consolidation agent such as fly ash and sand as an aggregate are added to the mixer 18 to obtain the required design strength.
The mixture is re-kneaded to produce the second mixed soil 7 containing aggregate. This is the second step. Here, reference numeral 19 in the figure is a secondary mixed soil production and supply device, which includes a suction section 20 that sucks the paste-like primary mixed soil 5,
7, a mixer 18, a pump (not shown), etc. Next, in creating the first mixed soil 5, from the lower end of the excavation shaft 1, instead of the earth and sand consolidation agent 2 in the first step, the second mixed soil 7 containing aggregate produced in the second step is extruded into the excavation hole. 8, pull up the excavation shaft 1 and fill the excavation hole 8 with the secondary mixed soil 7 containing aggregates from the bottom upwards, thereby filling the excavation hole 8 with the secondary mixed soil 7 containing aggregates. Pile 9 filled with
form. This is the third step. In the third step, the hose 16 is connected to the second mixed soil production and supply device 19. In addition, when the secondary mixed soil 7 containing aggregate is squeezed into the excavation hole 8 during the third step,
As time goes on, the primary mixed soil 5 constituting the primary mixed soil 5 is successively lifted onto the ground. The second mixed soil 7 is then filled into the excavation hole 8 from the lower end of the excavation shaft 1 under pressure. At this time, the excavation shaft 1 may be pulled up while rotating, or may be pulled up without rotating. In addition, the excavation shaft 1 and the primary mixed soil 5 are pushed upward by pressure filling the excavated hole 8 with the aggregate-containing secondary mixed soil 7 from below. 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 that provides the necessary bending strength and other strength is built into the pile 9. 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 soil 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. to the first mixed soil lifted to the ground by the excavation of the excavation shaft. The second step is to add soil consolidation agent and sand as an aggregate to obtain the required strength and knead it again to produce the second mixed soil containing aggregate, and in the preparation of the first mixed soil. After the lower end of the excavation shaft reaches a predetermined position, the second mixed soil containing aggregate produced in the second step is extruded from the lower end of the excavation shaft instead of the soil consolidation agent in the first step and filled into the excavation hole. In the third step, the excavation shaft is pulled up and a pile filled with the secondary mixed soil is formed in the excavation hole, so that the final strength is maintained throughout the entire length of the excavation hole in the vertical direction. The piles are constructed by filling with the secondary mixed soil containing aggregate adjusted to the following conditions, which has the advantage that piles with a predetermined strength can be easily formed. In addition, if the excavated soil excavated in the first step is clayey, there is no sand to serve as aggregate in the excavated soil, so the first mixed soil is mixed with cement milk and is further solidified in the second step. Even if a binder is mixed, it is not possible to obtain a pile with the required design strength because there is no aggregate, but in the second step of the present invention, a soil binder and an aggregate as an aggregate are added to the first mixed soil in the second step. Since the second mixed soil is produced by adding sand, etc. and re-mixing, even if the excavated soil is clay, sand, etc. as aggregate is mixed in in the second process, so it is difficult to create piles with the required design strength. It can be formed reliably, and in order to adjust it to the required design strength, sand can be mixed in the second process.
This reduces the amount of soil and solidification agent mixed in during the process, reducing costs. Furthermore, since the mixed soil removed above ground is reused in forming the piles, there is less need to dispose of the removed earth and sand, resulting in a significant cost reduction. In addition, since the first mixed soil is formed by mixing excavated soil and soil consolidation agent, the first mixed soil prevents the hole from collapsing during excavation and during filling with the second mixed soil. 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 will be replaced by excavated soil and earth. Since it is a mixture with a hardening agent, the pile that is finally formed is mainly composed of the secondary mixed soil and is made entirely of a mixture of excavated soil and sand hardening agent.

[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 formation and a cross-sectional view at the time of forming the pile, Figures 3a and b are a schematic front view showing another example of the same excavator as above, and a cross-sectional view at the time of forming the first mixed pile. Te, 1
is the excavation shaft, 2 is the soil consolidation agent, 3 is the ground, and 5 is the first
7 is the secondary mixed soil, 8 is the excavation 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 soil in the soil as the excavation progresses. The first step is to reach the lower end of the excavation shaft at a predetermined position, and the first mixed soil lifted to the ground by the excavation of the excavation shaft is mixed with soil consolidation agents such as cement and fly ash, and sand as aggregate. a second step of adding the following ingredients to obtain the required strength and kneading the mixture again to produce a secondary mixed soil containing aggregate;
In the preparation of the first mixed soil, after the lower end of the excavation shaft reaches a predetermined position, the second mixed soil containing aggregate produced in the second step is added from the lower end of the excavation shaft instead of the earth and sand compacting agent in the first step. While pressing out and filling the excavation hole, the excavation shaft is pulled up, and the second
A method for constructing piles in the ground, comprising a third step of forming piles filled with mixed soil.