JP2021025396A - Artificial water shut-off soil used in water shut-off zone of reservoir bank body - Google Patents

Abstract

To provide an artificial water shut-off soil having a physical value required for a water shut-off soil used in a water shut-off zone of an inclined water shut-off zone type reservoir bank body at a price of a mountain soil used before.SOLUTION: The water shut-off soil is obtained by stirring and mixing an improvement soil obtained by adding lime to a construction generating soil generated as a construction by-product in a construction work and a civil engineering work and improving the soil with an alluvial marine clay that is called Ariake clay and is widely distributed in an Ariake sea coast area in a weight ratio of 85:15 and 65:35. This coincides with a physical value of a water shut-off soil represented by "reservoir maintenance design guideline", and the artificial water shut-off soil can be provided at a price of a mountain soil used before.SELECTED DRAWING: Figure 5

Description

The present invention is a shield for a pond (reservoir) artificially created so that water can be stored and taken in order to secure water for agriculture in an area where precipitation is low and the river basin is not blessed with a large river. Regarding artificial blade gold soil, which is a water material.

As shown in the embankment cross section of Fig. 1, the structure of the embankment of a typical inclined impermeable zone type reservoir is located upstream of the impermeable portion of the embankment, and has a transition function of the impermeable portion. It is composed of the target embankment, the blade metal soil for the purpose of water blocking the reservoir embankment, and the pod soil that is located on the downstream side of the embankment and has the function of maintaining the stability of the embankment. Reservoir maintenance is carried out in accordance with the "Land Improvement Project Design Guideline" Reservoir Maintenance "(May 2015)" (supervised by the Development Department, Rural Promotion Bureau, Ministry of Agriculture, Forestry and Fisheries, published by the Agricultural and Rural Engineering Association). ing. Among them, regarding "water-impervious", which is one of the material judgments used for construction, it is defined as "a guideline is when ^{the hydraulic conductivity of the compacted soil material is smaller than 1 x 10-7 m / sec".} ing. At the same time, "generally, as a particle size for ensuring water impermeability, it is a guideline that a clay content of 0.005 mm or less is contained in an amount of about 5% or more." In addition, the water-impervious zone particle size range, semi-permeable zone particle size range, and water-impervious zone particle size range of materials in major zone-type fill dams (similar to reservoirs) constructed by the Ministry of Agriculture, Forestry and Fisheries are listed. Therefore, it is desirable that the particle size range of the pond blade metal soil also falls within this water-impervious zone particle size range. There are about 200,000 irrigation ponds nationwide, and many aging irrigation ponds have been damaged by natural disasters such as recent heavy rains and earthquakes, so it is expected that there will be an increase in reservoir maintenance projects and an increase in demand for impermeable materials. , It is important to secure the embankment embankment necessary for disaster prevention repair work. However, with the depletion of mountain soil that meets the physical characteristics required for the blade metal soil used for the impermeable zone of the embankment, artificial blade metal soil is being developed.

Hereinafter, the conventional technique will be described. Soil improvement method (see, for example, Patent Document 1), which improves impermeable performance and soil function by mixing swellable layered silicate minerals such as bentonite with soil such as aged soil that constitutes an impermeable civil engineering structure. A method of stirring and mixing a solidifying material in the bottom mud that has settled and accumulated at the bottom of the embankment to make an embankment material (see, for example, Patent Document 2), excavating and removing the embankment soil of the part to be reconstructed of the earthen dam There is a method of constructing an embankment as an improved soil by mixing an appropriate amount of a soil improving agent with the soil and stirring with a continuous mixer (see, for example, Patent Document 3).

The method of Patent Document 1 is a soil improvement method for improving water-impervious performance and soil function by mixing a swelling layered silicate mineral such as bentonite with soil such as aged soil constituting the impermeable civil engineering structure. This is the embankment blade soil that has been reused and recycled by improving the soil quality of the aged blade metal soil of the reservoir body by this method.

The method of Patent Document 2 includes a stirring and mixing step of stirring and mixing a solidifying material in the bottom mud that has settled and accumulated at the bottom of a reservoir to obtain a mixture, and a curing of the mixture obtained in the stirring and mixing step for a predetermined curing period. It is provided with a curing step of solidifying to obtain a solidified mixture and a crushing step of crushing the solidified mixture obtained in the curing step to a desired size to obtain crushed pieces, and the predetermined curing period is 1 to 5 days. It is a filling material characterized by a period within a certain range.

In the method of Patent Document 3, the embankment soil of the part to be reconstructed of the soil dam is excavated and removed, and an appropriate amount of a soil conditioner such as bentonite is mixed with the excavated embankment soil and stirred with a continuous mixer to obtain improved soil. This is a method of constructing an embankment by returning the soil to the excavated and removed part of the original embankment and repeating laying and rolling.

Japanese Unexamined Patent Publication No. 2005-325616 Japanese Unexamined Patent Publication No. 2000-248538 Japanese Unexamined Patent Publication No. 2005-210626

In the conventional method described in Patent Document 1 above, bentonite is expensive because the ore deposits that can be mined are limited, and the price of artificial blade metal soil added and used is also expensive. The method described in Patent Document 2 requires a process of mixing the solidifying material, curing for several days, and adjusting the particle size, which makes continuous processing impossible and the processing cost is high. The method described in Patent Document 3 requires a soil conditioner which is one of a neutral soil conditioner, a plaster-based neutral soil conditioner, bentonite, and a soil conditioner combining cement and plaster. Yes, the processing cost is high. Neither is available at the price of mountain soil that has been used before.

The present invention attempts to solve the above-mentioned drawbacks by realizing low-cost raw material selection and low-cost processing.

As a result of various studies to achieve the above objectives, the main raw material is improved soil that has been subjected to soil improvement treatment by adding lime to the construction-generated soil generated as a construction by-product in construction work and civil engineering work, and with Ariake clay. The object of the present invention can be achieved by adding alluvial marine clay, which is widely distributed in the coastal area of the Ariake Sea, which has an excellent water-impervious property, and mixing it uniformly to obtain an artificial blade metal soil that has both features. I found it.

The problem-solving means is to grasp the values of the above-mentioned improved soil and alluvial marine clay with respect to the physical properties such as hydraulic conductivity, particle size range, and adhesive strength required for the blade metal soil, and satisfy the physical property values required for the blade metal soil. It has been found that the object of the present invention can be achieved by defining the mixing ratio range of the two.

The actions of the above problem-solving means are as follows. That is, the hydraulic conductivity of the improved soil obtained by adding lime to the construction-generated soil generated as a construction by-product in construction work and civil engineering work to improve the soil quality is 1 × ^10-6 m / sec, which is required for the blade metal soil. Although it is larger than the physical property value, it is used as the main raw material, and the hydraulic conductivity is 1 × ^10-11 m / sec, which is 4 orders of magnitude smaller than the physical property value required for the blade metal soil, and it is called Ariake clay. By mixing Okizumi marine clay, which is widely distributed in the coastal area of the Ariake Sea, at a weight ratio of 85:15 to 65:35, the hydraulic conductivity is 1 × ^10-7 m, which is the physical property value required for blade soil. It has been found that the present invention can be achieved with values of / sec or less and other physical properties that can be used as artificial blade clay.

By implementing the present invention as described above, low-cost treatment can be performed using inexpensive improved soil and alluvial marine clay, and the physical properties required for the blade metal soil used for the impermeable zone of the embankment can be obtained. It is possible to provide the artificial blade gold soil that fills the price of the mountain soil that has been used for a long time.

It is a cross-sectional view of the embankment of the reservoir. This is a facility that produced the improved soil of the example. It is a photograph of the improved soil of the example. It is a photograph of alluvial marine clay called Ariake clay of the example. It is a particle size distribution map of an Example.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. In addition, the ratio of the compounding component in each example is expressed by mass%.

FIG. 2 is a photograph of a treatment facility in which lime is added to soil generated as a construction by-product in construction work and civil engineering work to improve the soil quality. FIG. 3 is a photograph of the improved soil produced at this facility. The particle density of improved soil in the 2.660g / cm ^3, meets the "pond maintenance design guidelines" published in 2.6g / cm ³ or more blades Fri Sat have to. The compaction strength exceeds the values for roadbed materials and embankment materials, and they are shipped as roadbed materials and embankment materials. The particle size distribution of this improved soil, which is described as improved soil in FIG. 5, is within the particle size range of the impermeable zone shown by the broken line in FIG. 5, but contains about 5% or more of clay content of 0.005 mm or less. The value that is set as a guide is about 1%. The hydraulic conductivity is 1 × 10 ^{-6 m / sec, which does not meet the value of 1 × 10 -7} m / sec or less of the blade metal soil described in the “Reservoir Maintenance Design Guideline”. For these reasons, this improved soil cannot be used as blade metal soil.

FIG. 4 is a photograph of alluvial marine clay widely distributed in the Ariake Sea coastal area called Ariake clay. The particle density of Ariake clay is 2.767g / cm ^3, meets the "pond maintenance design guidelines" published in 2.6g / cm ³ or more blades Fri Sat have to. The compaction strength is below the measurable minimum value and cannot be used as blade metal soil. The particle size distribution of this Ariake clay, which is described as Ariake clay in FIG. 5, is far outside the particle size range of the impermeable zone shown by the broken line in FIG. 5, and cannot be used as a blade metal soil. The hydraulic conductivity is 1 x ^{10-11 m / sec, which meets the value of 1 x 10-7} m / sec or less of the blade metal soil listed in the "Reservoir Maintenance Design Guideline" and has excellent water impermeability. doing.

The particle density of the artificial blade metal soil of the present invention, which is a uniform mixture of the improved soil and Ariake clay at a weight ratio of 65:35, is 2.697 g / cm ³ , and the blade metal soil described in the "Reservoir Maintenance Design Guideline". It satisfies 2.6 g / cm ³ or more of. The compaction strength exceeded the value for embankment materials such as embankments. The particle size distribution of the artificial blade metal soil, which is a mixture of improved soil and Ariake clay described as 65:35 in FIG. 5 at a weight ratio of 65:35, is shown by the broken line in FIG. Within the range, the value of the clay content of 0.005 mm or less is about 7%. Further, the hydraulic conductivity is 1 × 10 ^-9 m / sec, which ^{satisfies the value of 1 × 10 -7} m / sec or less of the blade metal soil, indicating that it can be used as an artificial blade metal soil.

The particle density of the artificial blade gold soil of the present invention in which the ratio of the improved soil and Ariake clay is uniformly mixed at a weight ratio of 85:15 is 2.676 g / cm ³ , and the blade described in the "Reservoir Maintenance Design Guideline" It fills 2.6 g / cm ³ or more of gold and clay. The compaction strength exceeded the value for embankment materials such as embankments. The particle size distribution of the artificial blade metal soil, which is a mixture of improved soil and Ariake clay described as 85:15 in FIG. 5 at a weight ratio of 85:15, is shown by the broken line in FIG. Within the range, the value of the clay content of 0.005 mm or less is about 5%. Further, the hydraulic conductivity is 1 × ^10-8 m / sec, which ^{satisfies the value of 1 × 10 -7} m / sec or less of the blade metal soil, indicating that it can be used as an artificial blade metal soil.

The artificial blade metal soil of the present invention is called Ariake clay, which is mainly made of improved soil obtained by adding lime to soil generated as a construction by-product in construction work and civil engineering work to improve the soil quality. It is obtained by adding alluvial marine clay, which is widely distributed in the coastal area of the Ariake Sea, and stirring and mixing. This matches the physical characteristics of the blade metal soil shown in the "Reservoir Maintenance Design Guideline" and can be provided at the price of mountain soil that has been used for a long time.

Claims (1)

Weight of improved soil obtained by adding lime to soil generated as a construction by-product in construction work and civil engineering work to improve the soil quality, and offshore marine clay widely distributed in the Ariake Sea coastal area called Ariake clay. Stirring and mixing at a ratio of 85:15 to 65:35, the particle size distribution is within the particle size range of the blade metal soil used for the water-impervious zone of the pond embankment, and the clay content of 0.005 mm or less is 5%. As described above, the artificial blade clay is characterized in that the particle density is 2.6 g / cm ³ or more and the water permeation coefficient is 1 × 10 ^{-7 m / sec or less.}