JPH0433927B2 - - Google Patents

Description

[Detailed description of the invention] 【Technical field】

The present invention relates to an invention for constructing a soil cement underground wall for forming an underground dam or salt water backflow prevention underground embankment underground.

[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 backflow of salt water. This conventional soil cement underground wall is made by excavating the ground with an excavator while squirting 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 invented in view of the above-mentioned conventional problems, and its purpose is to drain excess water above the soil cement underground wall when the groundwater level rises. It is possible to overflow the water, and there is no risk of the ground surface becoming wet or overflowing, and the soil cement underground wall made of cement milk and excavated earth and sand can be used to prevent underground dam embankments and salt water. To provide a method for constructing an overflow section for surplus water in a soil cement underground wall, which is easy to construct and can be constructed at low cost because an underground embankment for preventing backflow is formed.

[Disclosure of the invention]

The method for constructing a surplus water overflow part in a soil cement underground wall of the present invention is a method for constructing a soil cement underground wall 1 for forming an underground dam embankment or a salt water backflow prevention underground embankment underground. , Excavate the ground 3 while spouting the water-soluble polymer liquid from the ground surface 2 to an arbitrary depth of the ground 3 to form an upper excavation part 4 filled with water-soluble polymer turbid soil, and form the upper excavation part 4 below the upper excavation part 4. The ground 3 is excavated while spouting cement milk continuously to the upper excavation part 4, and the soil cement underground wall 1 is made of a mixture of cement milk and excavated earth and sand.
and then injecting a substance for decomposing the water-soluble polymer into the water-soluble polymer mixed soil in the upper excavation part 4 to give water permeability to the upper excavation part 4 part. By employing such a method, the above-mentioned object of the present invention has been achieved. In other words, in the present invention, the earth surface 2
The ground 3 is excavated while spouting water-soluble polymer liquid to an arbitrary depth of the ground 3 to form an upper excavation part 4 filled with water-soluble polymer turbid soil, and an upper excavation is made below the upper excavation part 4. Since the soil cement underground wall 1 is formed by excavating the ground 3 while spouting cement milk continuously in the section 4, the soil cement underground wall 1 is formed downward from an arbitrary depth from the ground surface 2. By simply changing the liquid ejected from the water-soluble polymer liquid to cement milk, the soil cement underground wall 1 can be formed in the same way as forming the soil-cement underground wall 1 from the ground surface 2. There is no collapse of the surrounding ground, and after the soil cement underground wall 1 is formed, a substance for decomposing water-soluble polymers is injected into the water-soluble polymer mixed soil in the upper excavation part 4. is restored to the original permeable ground, so even if the groundwater level rises, excess water will overflow from the upper part of the soil cement underground wall 5 in the ground 3 and flow underground, causing the area near the ground 2 to It was constructed to prevent water from turning into a wetland or from overflowing from the surface. 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 the water-soluble polymer liquid or cement milk can be spouted from any part of the bit 8 or the rotating vertical shaft 7. Therefore, in places where underground dams, embankments, or salt water backflow prevention underground embankments are to be formed, use the excavator 6 to drill CMC (carboxy methyl
The ground 3 is excavated while spouting a water-soluble polymer liquid such as cellulose, and the excavated soil and water-soluble polymer liquid are mixed and stirred by the stirring means 9 to form water-soluble polymer turbid soil in the excavation hole. This forms an upper excavation section 4 filled with. The water-soluble polymer liquid spouted here is, for example, a mixture of 95 parts by weight of water and 5 parts by weight of CMC. After excavating and forming the upper excavation part 4 from the ground surface 2 to the desired depth of the ground 3 using the excavator 6 in this manner, the excavator 6 excavates the ground while spouting cement milk instead of the water-soluble polymer liquid. 3 will continue to be excavated. In the embodiment shown in the accompanying drawings, cement milk is ejected from the depth shown in Figure 1b for excavation. In this case, cement milk and excavated soil are mixed and stirred, and the mixture of cement milk and excavated soil is filled into the excavated hole that is continuous below the upper excavated portion 4. After excavating the lower excavation part 11 to the desired depth of the ground 3 (that is, the impermeable layer 10) in this way, while stirring and mixing the cement milk and the excavated soil (spouting the cement milk as necessary) while)
The rotating shaft 7 is pulled up, and when the liquid spout provided on the rotary shaft 7 or the bit 8 is located near the lower end of the upper excavation part 4 (the state shown in Fig. 1(f)), water-soluble water is released from the liquid spout. Inject a substance to decompose the polymer (if you have been spouting cement milk until then, inject the substance to decompose the water-soluble polymer instead of jetting cement milk) and stir with a stirring means. By doing so, the water-soluble polymer turbid soil and the substance that decomposes the water-soluble polymer are mixed. Enzymes such as cellulase are used as substances for decomposing water-soluble polymers, and for example, a mixture of 99.9 parts by weight of water and 0.1 parts by weight of cellulase is used. In this way, the rotating shaft 7 is pulled up while injecting a substance that decomposes water-soluble polymers. The excavators 6 are used to excavate one after another in the same manner. The mixture of cement milk and excavated earth and sand is filled in the lower excavation part 11, and the soil cement underground wall 1 is formed by hardening the cement milk. On the other hand, in the upper excavation section 4 where the water-soluble polymer mixed soil and the substance for decomposing the water-soluble polymer are mixed, the water-soluble polymer is decomposed and becomes low molecular weight, resulting in water permeability. Above the cement underground wall 1, the upper excavated part 4 is made to have the same water permeability as the original ground 3, and becomes a surplus water overflow part. In this way, an underground dam embankment or an underground wall to prevent salt water backflow is formed, and the soil cement underground wall 1 prevents groundwater (or backflow salt water) from flowing and stores water underground (or salt water However, the water level rises and the soil cement underground wall 1
When the excess water exceeds the upper end, it permeates through the excess water overflow area, which is the remains of the upper excavation part above the soil cement underground wall 1, and flows as shown by the arrow in Figure 2. , it is possible to prevent the vicinity of the ground surface 2 from turning into a wetland and to prevent groundwater from gushing out from the ground surface 2.

【Effect of the invention】

In the present invention, as described above, the ground is excavated while spouting water-soluble polymer liquid from the ground surface to an arbitrary depth in the ground to form an upper excavation portion filled with water-soluble polymer turbid soil, The ground is excavated while spouting cement milk below the upper excavation part to form a soil-cement underground wall in which cement milk and excavated soil are mixed. A substance to decompose water-soluble polymers was injected into the polymer-mixed soil to make the upper excavation part permeable, so if the groundwater level rises, the upper part of the soil-cement underground wall will be removed. It can be constructed without the risk of water flowing, turning the area near the ground into a wetland, or gushing out groundwater from the ground, as was the case in the past. A simple series of construction methods in which the ground is excavated with an excavator and the excavated soil and liquid are mixed by simply changing the molecular liquid to cement milk and the cement milk to a substance that decomposes the water-soluble polymer liquid. This eliminates the need to remove large amounts of excavated soil.
In addition, when forming a soil cement underground wall below a certain depth, it is possible to prevent the ground surrounding the upper excavation part from collapsing and reliably form the soil cement underground wall below. Moreover, after forming the soil cement underground wall, water permeability can be easily imparted to the upper excavated portion.

[Brief explanation of drawings]

Figures 1 a, b, c, d, e, f, and g are cross-sectional views showing the construction order of the present invention, Figure 2 is a cross-sectional view of the underground dam constructed by the same method, and Figures 3 a and b are 1 is a front view and a side view showing an example of an excavator used in the present invention, in which 1 is a soil cement underground wall; 2 is a ground surface;
3 is the ground, and 4 is the upper excavation part.

Claims (1)

[Claims] 1. In the method of constructing a soil cement underground wall for forming underground dam embankments or salt water backflow prevention underground embankments, the ground is ground while spouting water-soluble polymer liquid from the ground surface to an arbitrary depth in the ground. Excavate to form an upper excavation section filled with water-soluble polymer turbid soil, and excavate the ground below the upper excavation section in a continuous manner to the upper excavation section while spouting cement milk to form cement milk and excavated soil. form a soil-cement underground wall mixed with water-soluble polymer, and then inject a substance to decompose the water-soluble polymer into the soil mixed with water-soluble polymer in the upper excavation part to give water permeability to the upper excavation part. A method for constructing an overflow section for excess water in a soil cement underground wall, characterized by: