JPH0433928B2 - - Google Patents

Description

[Detailed description of the invention] 【Technical field】

TECHNICAL FIELD The present invention relates to a soil cement underground wall having a water-permeable portion in the upper part for forming an underground dam or salt water backflow prevention underground embankment, and a method for constructing the same.

[Background technology]

Conventionally, it has been proposed to form a soil cement underground wall when forming an underground dam to store groundwater or an underground wall to prevent salt water from flowing back underground. This conventional soil cement underground wall is made by excavating the ground with an excavator while spouting cement milk from the ground surface to a predetermined depth (impermeable layer) in the ground, and mixing the cement milk and excavated soil to create soil cement. It formed an underground wall. In this way, in the past, soil cement underground walls were formed continuously from the ground surface to the impermeable layer underground. By the way, if the soil cement underground wall is formed all the way to the ground surface as described above, in an underground dam with the soil cement underground wall as an underground embankment, if the water level of the groundwater stored in the underground dam rises, the underground There were problems with the ground on the front side becoming wet and water overflowing from the surface. This also applies to soil cement underground walls that are formed to prevent salt water from flowing back.

[Purpose of the invention]

The present invention was devised in view of the above-mentioned conventional problems, and its purpose is to drain excess water from the soil cement permeability of the upper part of the soil cement underground wall when the groundwater level rises. Water can permeate through the walls, so there is no risk of the ground becoming wet or overflowing from the ground.Furthermore, the upper and lower parts of the walls are basically soil-cement underground walls, so they are not strong. A soil cement underground wall with a permeable wall at the top and its construction method, which is strong and easy to install because all you have to do is select where to put the foaming agent and where not to put it in. is to provide.

[Disclosure of the invention]

The present invention provides a soil cement underground wall 1 formed underground to serve as an underground dam embankment or a salt water backflow prevention underground embankment.
The specified invention is a structure of a soil cement underground wall having a permeable wall at the upper part, which is characterized in that the upper part is a soil cement permeable wall 2 having air bubbles for water permeation, and also used for underground dam embankments and salt water backflow prevention areas. Soil cement underground wall 1 for forming an underground embankment
In the method for constructing a soil cement underground wall 1, the upper part of the soil cement underground wall 1 is formed by excavating while squirting cement milk containing a foaming agent and mixing the cement milk containing a foaming agent and excavated soil. A method for constructing a soil-cement underground wall having a permeable wall at the upper part, characterized in that the lower part of 1 is formed by excavating while spouting cement milk and mixing cement milk and excavated earth and sand, is a combined invention. By employing such a configuration, the above-mentioned object of the present invention is achieved. That is, in the present invention, as described above, the upper part of the soil cement underground wall 1 is formed as the soil cement permeable wall 2 having air bubbles for water permeation, so that excess water can permeate through the soil cement permeable wall 2 portion and reach the ground surface. It is possible to prevent the area around 3 from turning into a wetland or from groundwater gushing out from the ground surface 3. Also, during construction, cement milk is squirted out while excavating, and the cement milk and excavated soil are mixed to create a soil-cement ground. The soil cement permeable wall part 2 can now be easily formed in the upper part of the soil cement underground wall 1 by simply mixing a foaming agent into the cement milk only in the upper part in the process of forming the inner wall 1. It is. The present invention will be explained in detail below with reference to Examples. FIG. 3 shows one example of an excavator 6 used in the present invention.
The excavator 6 in FIG. 3 is a multi-axis excavator with a plurality of rotating vertical shafts 7 arranged in parallel, and a bit 8 is provided at the lower end of each rotating vertical shaft 7. A stirring means 9 such as a stirring blade or a screw section is provided.
A liquid spout is provided so that cement milk can be spouted from any part of the bit 8 or the rotating vertical shaft 7. Therefore, at a place where an underground dam embankment or an underground embankment to prevent salt water backflow is to be formed, the excavator 6 is used to squirt cement milk containing a foaming agent from the ground surface 3 to an arbitrary depth in the ground 4.
At the same time, the excavated soil and cement milk containing a foaming agent are mixed and stirred by a stirring means 9 to form an upper excavation section 5 filled with a mixture of the excavated soil and cement milk containing a foaming agent. be. In this way, the excavator 6 excavates the soil from the ground surface 3 to the ground 4.
After excavating and forming the upper excavation part 5 to an arbitrary depth, the ground 4 is continued to be excavated with an excavator 6 while spouting cement milk instead of cement milk containing a foaming agent. In the embodiment shown in the accompanying drawings, cement milk is ejected from the depth shown in FIG. 1(c) to excavate. In this case, cement milk and excavated soil are mixed and stirred, and the mixture of cement milk and excavated soil is filled into an excavated hole that is continuous below the upper excavated portion 5. In this way, the desired depth of the ground 4 (that is, the impermeable layer 10)
After excavating the lower excavation part 11 up to the point, the rotary shaft 7 is pulled up while stirring and mixing the cement milk and the excavated soil (spouting the cement milk as necessary). With the liquid spout located near the lower end of the upper excavation part 4 (state shown in Figure 1 f), foaming agent-containing cement milk is spouted from the liquid spout (if cement milk has been spouted until then) Instead of squirting cement milk, inject cement milk with a foaming agent),
The rotating shaft 7 is pulled up while stirring the foaming agent-containing cement milk and the excavated earth and sand by stirring with the stirring means 9. Thereafter, before the mixture of excavated earth and sand and cement milk containing a foaming agent hardens, a steel pipe 12 coated with a lubricant such as wax is inserted into the upper excavation part 5 as shown in FIG. 1h. The excavators 6 are used to excavate one after another in the same manner. As the cement milk hardens, a soil cement underground wall 1 is formed as a whole, and in this case, in the lower part of the soil cement underground wall 1, a mixture of cement milk and excavated soil is inside the lower excavation part 11. The soil cement water-permeable wall 14 is made of water-impermeable water-permeable wall 14 because it is formed by hardening cement milk. On the other hand, in the upper part of the soil-cement underground wall 1, a mixture of cement milk containing a foaming agent and excavated soil is filled in the upper excavation part 5, and as the foaming agent foams and the cement milk hardens, a large number of This is a soil cement water permeable wall 2 with continuous cavities and water permeability. When the steel pipe 12 is pulled out with a jack or the like after hardening, an annular hole 13 is formed in the soil cement permeable wall 2 where the steel pipe 12 has been pulled out, and water permeates from the direction of arrow A in Figure 2A. , the water flows through the annular hole 13 as shown by the arrow B in Figure 2A, and permeates as shown by the arrow C in Figure 2A.If the annular hole 13 is formed in this way, the water will flow more smoothly. It is permeable to water. To give an example here, if the diameter of the soil cement permeable wall 2 is 55 cm, the diameter of the steel pipe 12 is
If it is 45 cm, the distance between the outer periphery of the soil cement permeable wall 2 and the outer periphery of the annular hole 13 is 5 cm, and groundwater only has to pass through this 5 cm. In other words, in this case, the cavity formed by the bubbles should be continuous in the radial direction by about 5 cm.
In addition, FIG. 2b shows another embodiment of the present invention, and in this embodiment, a bottomed steel pipe or the like is inserted to form a hole 1 in the soil cement permeable wall 2 at the stage shown in FIG. 1h.
3'. In this case, water permeates into the hole 13' from the direction (b) in FIG. 2, and through the hole 13' in the direction (b) in FIG. As described above, the soil cement underground wall 1 is formed to serve as the embankment of an underground dam or an underground embankment for preventing salt water backflow. (or the backflow of saltwater) is prevented from flowing and water is stored underground (or the backflow of saltwater is prevented)
However, when the water level rises, excess water permeates through the soil cement permeable wall 2 above the soil cement underground wall 1, and as a result, the area near the ground surface 3 does not become wetland, and the ground surface This can prevent groundwater from gushing out from 3.

【Effect of the invention】

In the present invention, as described above, the upper part of the soil cement underground wall formed underground to serve as the embankment of an underground dam or an underground embankment for preventing salt water backflow is a soil cement permeable wall having air bubbles for water permeation. Therefore, if the groundwater level rises, excess water can be allowed to permeate through the soil cement permeable wall above the soil cement underground wall, preventing the area near the ground surface from becoming wetland or causing groundwater to gush out from the ground surface. There is no risk of it happening. Furthermore, the upper and lower sections are basically soil-cement underground walls, so they are very strong. Furthermore, during construction, the upper part of the soil cement underground wall is excavated while squirting cement milk containing a foaming agent, and the cement milk containing a foaming agent and excavated soil are mixed to form the soil cement underground wall. The lower part of the wall is formed by excavating while squirting cement milk and mixing the cement milk and excavated soil, so there are two areas in which a foaming agent is added during the construction process of a soil-cement underground wall and where it is not. By selecting , it is possible to easily form a soil cement underground wall with a soil cement permeable wall at the top.

[Brief explanation of drawings]

Figure 1 a, b, c, d, e, f, g, h, i are cross-sectional views showing the construction order of the present invention; is a front sectional view, h and i are side sectional views, FIGS. 2 a and b are cross sectional views of the present invention and sectional views of other embodiments, and FIGS. 3 a and b are excavators used in the present invention. 1 is a front view and a side view, 1 is a soil cement underground wall, and 2 is a foamed soil cement permeable wall.

Claims (1)

[Claims] 1. The invention is characterized in that the upper part of a soil-cement underground wall formed underground to serve as an embankment of an underground dam or an underground embankment for preventing salt water backflow is formed as a soil-cement permeable wall having air bubbles for water permeation. A soil-cement underground wall with a permeable wall on top. 2. In a method of constructing a soil cement underground wall to form an underground dam embankment or salt water backflow prevention underground embankment, the upper part of the soil cement underground wall is excavated while squirting cement milk containing a foaming agent. The lower part of the soil-cement underground wall is formed by mixing cement milk with a foaming agent and excavated soil, and the lower part of the soil-cement underground wall is formed by excavating while spouting cement milk and mixing cement milk and excavated soil. A construction method for a soil cement underground wall with a characteristic permeable wall at the top.