JP7051583B2 - How to purify contaminated weathered rocky ground - Google Patents

Description

The present invention relates to a method for purifying contaminated weathered rocky ground.

Conventionally, many purification methods have been proposed as methods for purifying ground and groundwater contaminated with pollutants. Japanese Patent Application Laid-Open No. 11-207375 describes injecting water containing a nutritional composition for microorganisms into a contaminated groundwater zone from an injection well, and in a method for repairing groundwater pollution in which contaminants are decomposed by microorganisms, ozone is added to the injected water. Disclosed is a method for repairing groundwater pollution, which comprises dissolving and injecting water, or injecting the injected water and dissolved ozone water. According to this method, it is possible to prevent the dissolved oxygen concentration and the nutrient composition concentration from rapidly decreasing as the distance from the injection well increases, and it is possible to greatly improve the long-distance reachability of these underground. As a result, it becomes possible to apply bioremediation to decompose and remove pollutants using microorganisms in a wider underground area.

Japanese Patent No. 4160728 describes a device for purifying contaminants containing a halogenated organic compound, and a reducing agent tank for holding a reducing agent having a standard electrode potential of 300 mV to -2400 mV with respect to a standard hydrogen electrode at 25 ° C. It is provided with a nutrient source tank for holding a nutrient source of a dependent nutrient-type anaerobic microorganism, a well provided with a water absorbing portion and a draining portion, and the reducing agent is added to the water absorbed from the water absorbing portion. A purification device is disclosed in which a reducing agent from a tank and a nutrient source from the nutrient source tank are brought into contact with each other, drained from the drainage portion, and again absorbed from the water absorbing portion to circulate water. According to the present invention, contaminants containing halogenated organic compounds, particularly soil and groundwater, can be efficiently and easily purified in situ.

Japanese Patent Application Laid-Open No. 2014-79670 describes a permeable wall body containing a purifying agent that purifies a pollutant so as to intersect the flow direction of the contaminated groundwater in the ground downstream of the contaminated groundwater. Disclosed is a permeable groundwater purification wall characterized by having a plurality of rows of permeable wall bodies containing different types of the purifying agents separately in a permeable groundwater purification wall arranged in a direction. ing. According to the present invention, a plurality of rows of wall bodies are formed in the ground in the downstream area of contaminated groundwater by a plurality of granular piles, and at least one of the plurality of rows is compacted to form a plurality of rows. It is possible to construct a column transparent wall body in a short time and at low cost.

Japanese Patent Application Laid-Open No. 2015-217361 is a permeable columnar that is installed in an unsaturated layer and between a contaminated soil region existing in the unsaturated layer and groundwater in a horizontal or inclined manner. The groundwater purifier is disclosed. According to the present invention, the purifier formed in the unsaturated layer prevents the pollutants existing in the unsaturated layer from diffusing deeply and reaching the groundwater due to the infiltration or passage of rainfall. can do.

On the other hand, in contaminated ground such as an industrial waste treatment plant, there is a rocky ground in the lower part of a sand layer or a gravel layer. In order to utilize this site, it is necessary to purify the contaminated ground, but since pollutants do not penetrate into the rocky ground, the ground to be purified is a sand layer or a gravel layer. However, vertical and horizontal cracks called joints develop in rocky ground such as granite. Water and air enter along this crack and weather the granite. In the case of such weathered rocky ground, high-concentration pollutants permeate along the water path such as cracks, and it is necessary to purify the pollutants in the cracks.

Japanese Unexamined Patent Publication No. 11-207375 Japanese Patent No. 4160728 Japanese Unexamined Patent Publication No. 2014-79670 JP-A-2015-217361

However, in general, it is difficult to purify pollutants in cracks in rocky ground. And, conventionally, there is no disclosure about a method for purifying pollutants in weathered rocky ground.

Therefore, an object of the present invention is to provide a method for purifying pollutants in weathered rocky ground.

That is, the present invention solves the above-mentioned conventional problems, and is a method for purifying contaminated weathered rocky ground, in which step I for forming granular material piles on the weathered rocky ground and granular material. Alternatively, the present invention provides a method for purifying weathered rocky ground, which comprises a step II of impregnating the granular material pile with a purifying agent or injecting water into the granular material pile.

The present invention also provides a method for purifying the weathered rocky ground, wherein the granular material is one or more selected from sand, crushed stone, glass beads and resin beads. ..

Further, the present invention is characterized in that, in the step I, a hollow pipe is penetrated and pulled out into the weathered rocky ground by vibration or rotation, and a granular material pile is formed from the granular material in the hollow pipe. It provides a method for purifying quality ground.

Further, the present invention is characterized in that, in the step I, a weathered rocky ground is drilled, and then a fluidized granular material is injected into the drilling by press fitting to form a granular material pile in the drilling. The present invention provides a method for purifying the weathered rocky ground.

Further, the present invention is characterized in that the II step installs an injection well in the granular material pile and injects a purifying agent from the injection well or injects water from the injection well. It provides a method for purifying quality ground.

The present invention also provides a method for purifying the weathered rocky ground, characterized in that the water is circulating water from a pumping well formed in the weathered rocky ground.

Further, the present invention is characterized in that, in the II step, a permeation box containing a purifying agent is installed on the upper part of the granular material pile, and the purifying agent is permeated from the permeation box into the granular material pile. It provides a method for purifying rocky ground.

Further, in the present invention, the II step is a step of impregnating the granular material with a purifying agent, first performing the II step, and then carrying out the I step using the granular material containing the purifying agent as a pile material. The present invention provides a method for purifying the weathered rocky ground, which is characterized by forming a granular material pile containing a purifying agent.

According to the present invention, pollutants in weathered rocky ground can be efficiently purified.

It is a schematic diagram of the vertical cross section of the weathered rocky ground in the purification method of this invention. It is a schematic diagram of the cross section of the weathered rocky ground of FIG. It is a figure in which a granular material pile was placed in the weathered rock ground of FIG. It is a schematic diagram of the cross section of FIG. It is the figure which formed the injection well in the granular material pile of FIG. It is a schematic diagram of the cross section of FIG. It is the figure which installed the infiltration well on the upper part of the granular material pile of FIG.

In the present invention, the rocky ground is the rock defined in JGS3811-2011 (engineering classification method of rock) of the Japanese Geotechnical Society. That is, the bedrock is a natural ground composed of rocks, and the rocks are aggregates of minerals consolidated or bonded to various degrees, and are the ground materials of the bedrock portion not including the discontinuous surface. In general, discontinuities are distributed inside such rocky ground and are accompanied by various degrees of weathering / alteration.

In the present invention, the weathered rocky ground means that the "weathering degree" of the "fine classification" in the "major classification, middle classification, minor classification and fine classification" defined in JGS3811-2011 is w ₃ to w ₆ and "weathering degree". The "weathering / alteration state" in the "classification of the degree of weathering of the bedrock" is that of _w3 to _w6 . Specifically, in the boring core appraisal, the uniaxial compressive strength in the dry state of the bedrock is 400 kgf / cm ² or less, the joint density (average core length) is 30 cm or less, and the standard classification of joint openness is "some gaps occur" or. It is "weathered" or "extremely weathered" that is judged to be "not meshing".

In the present invention, the pollutants are not particularly limited, and are harmful substances flowing out from waste treatment plants and illegally dumped waste, factory effluents, and the like, and are, for example, benzene, toluene, xylene, phenol, cresol, and aromatic amines. , 1,4-Dioxane, dioxin, PCB, PCP (pentachlorophenol) and the like, and chain organic compounds such as trichloroethylene, tetrachloroethylene and dichloroethylene. In the present invention, pollutants have penetrated into the cracks in the weathered rocky ground. Contaminated weathered rocky ground can be known by prior boring core testing.

In the present invention, the step I is a step of forming a granular material pile on the weathered rocky ground. The granular material pile also includes a wall body having a continuous pile shape. Granular materials include sand, crushed stone, glass beads and resin beads. These granular materials can be used alone or in admixture of two or more. If the conventional sand pile construction method is applied using sand and crushed stone, sand piles and sand walls can be formed on the weathered rocky ground. Glass beads and resin beads can be used in place of sand or crushed stone, or mixed with sand or crushed stone, and if the conventional fluidized sand intrusion method is applied, granular material piles can be formed on weathered rocky ground. .. The granular material pile may be water permeable. As a result, the purifying agent can be infiltrated into the granular material pile. Further, in a large number of granular material piles, the distance between adjacent granular material piles is appropriately determined to be between 1 m and 3 m. Due to the formation of a large number of granular material piles in the weathered rocky ground, the hydraulic conductivity of the complex ground has increased significantly from ^10-6 to ^10-4 cm / sec to ^10-3 cm / sec. Improve. In addition, the hydraulic state of the ground can be changed from the pressured state to the non-pressured state, and the retention of the ground (specific production rate) can be increased. As a result, the purifying agent injected into the granular material pile penetrates into the crack, and the distance to the adjacent granular material pile is short, so that the purification efficiency is further improved. When the step II is carried out before the step I and the granular material contains the purifying agent in advance, the granular material in the step I contains the purifying agent.

Examples of the method for forming a granular material pile on the weathered rocky ground in the step I include a conventional sand pile construction method and a fluidized material press-in method. The sand pile construction method is a construction method in which a hollow pipe is driven into the weathered rocky ground by vibration or rotation, and a granular material pile is constructed from the granular material in the hollow pipe. As an example of the sand pile construction method, for example, a drawing step of penetrating a hollow pipe to a predetermined depth, pulling out the hollow pipe to an appropriate length, and discharging the granular material pile material in the hollow pipe to the pulling trace. There is a compaction sand pile construction method in which the process of re-penetrating the hollow pipe is repeated up to the ground surface to create compaction sand piles in the weathered rocky ground. At this time, the weathered rocky ground is expanded by the intrusive of the hollow pipe, the pressure is applied to the weathered rocky ground to expand the diameter of the pile by the re-intrusive rock, and the weathered rocky ground at the time of the intrusive and re-intrusive of the hollow pipe. Cracks are promoted due to the addition of vibration to the surface, and the penetration efficiency of the purifying agent can be improved.

As a fluidized material press-fitting method, a known granular material pile construction method in which a fluidized material containing a granular material, a fluidizing agent and water is press-fitted into a weathered rocky ground while maintaining a fluidized state and plasticized in the ground. Can be mentioned. In the fluidized material press-fitting method, the weathered rocky ground may be drilled in advance and the fluidized material may be press-fitted into the drilled hole. The press-fitted fluid does not need to be plasticized. In the fluidized material press-fitting method, pressure is applied to the weathered rocky ground by drilling or by fluidized material intrusion, cracks are promoted, and the infiltration efficiency of the purifying agent can be improved.

In the present invention, the step II is a step of impregnating the granular material or the granular material pile with a purifying agent or injecting water into the granular material pile. As a method of containing a purifying agent in the granular material pile, an injection well is installed in the granular material pile obtained in the step I, and the purifying agent is injected from the injection well, and the granular material pile obtained in the step I A method of installing a permeation box on the upper part and infiltrating the purifying agent from the permeation box into the granular material pile can be mentioned. Further, in the method of containing the purifying agent in the granular material, the step II is first performed, the purifying agent is contained in the granular material in advance, and then the granular material containing the purifying agent is used as a pile material in the step I. Is applied in the method of forming a granular material pile containing a purifying agent. Examples of the method of preliminarily containing a purifying agent in a granular material include a method of infiltrating a liquid purifying agent into the granular material and a method of obtaining a mixture of the granular material and a granular or powder purifying agent. The method of incorporating the purifying agent into the granular material in advance is to first perform step II and then step I.

As a method of injecting the purifying agent from the injection well, a known method of pumping a liquid containing the purifying agent from the injection well by a pump can be mentioned. As a result, the purifying agent can be injected into the granular material pile, penetrate the crack, and purify the contaminants in the crack. As a method of injecting a purifying agent from an injection well, a method of attaching a pumping well to the weathered rocky ground and using a circulation method can be used. That is, in the weathered rocky ground, the granular material piles in which the injection wells are formed and the pumping wells are connected by cracks, and the pumping water containing the purifying agent pumped from the pumping wells, for example, adjusts the concentration of the purifying agent on the ground. In the tank, the purification agent concentration is adjusted and re-injected into the injection well. As a result, the pumping well, the purifying agent concentration adjusting tank, the injection well, the granular material pile, the crack and the pumping well are connected to form a circulation system, so that the purification period can be shortened.

Examples of the method of injecting water into the granular material pile include a method of installing an injection well in the granular material pile obtained in step I and injecting (watering) water from the injection well. Examples of the method of injecting water from the injection well include a method of circulating and injecting circulating water from a pumping well formed in the weathered rocky ground. That is, in the weathered rocky ground, the granular material pile in which the injection well is formed and the pumping well are connected by a crack, and the pumped water pumped from the pumping well is injected into the injection well. As a result, the pumping well, the injection well, the granular material pile, the crack and the pumping well are connected to form a circulation system, so that the purification period can be shortened.

In the method of infiltrating the purifying agent from the infiltration box into the granular material pile, the infiltration box communicates with the granular material pile and stores the liquid material containing the purifying agent, and is simply placed on the upper end of the granular material pile. A liquid containing a purifying agent is infiltrated into a granular material pile by a natural gravity drop. The size of the infiltration box is appropriately determined and can be installed in a part or all of a large number of granular material piles.

In the present invention, known granules or liquids can be used as the purifying agent, for example, iron powder, activated carbon, salts containing inorganic compounds as nitrogen sources and phosphorus sources, chemical oxidizing agents such as sodium persulfate and Fenton's reagent. Can be mentioned. These can be used alone or in combination of two or more. In the present invention, the water includes injection water or circulating water from a pumping well.

Next, the method for purifying the weathered rocky ground in the first embodiment of the present invention will be described with reference to FIGS. 1 to 6. The weathered rocky ground 12, which is the target ground of the purification method of this example, exists below the sand or gravel layer 11 on the ground surface. The weathered rocky ground 12 is a weathered rocky ground such as granite, and cracks 13 are present in the rocky ground, and pollutants are present in the cracks (FIGS. 1 and 2). ). The extent of contamination should be ascertained by a preliminary boring test. First, a large number of sand piles 2 are constructed on the weathered rocky ground 12 by a known method for creating wide-diameter sand piles, for example, at intervals of 2 m in a plan view. The number of sand piles 2 and the depth of the tip may be appropriately determined within a range covering the range of contamination.

Specifically, after penetrating the hollow pipe to a predetermined depth, the hollow pipe is pulled out to an appropriate length, and the sand pile material in the hollow pipe is discharged to the pull-out mark, and the hollow pipe is re-penetrated. The process is repeated sequentially up to the ground surface to create compacted sand piles 12 in the weathered rocky ground. At this time, the weathered rocky ground is expanded by the intrusive of the hollow pipe, the pressure is applied to the weathered rocky ground to expand the diameter of the pile by the re-intrusive rock, and the weathered rocky ground at the time of the intrusive and re-intrusive of the hollow pipe. The crack 13 is promoted due to the addition of vibration to the crack 14, a new crack 14 is generated, and the penetration efficiency of the purifying agent is improved. Further, a large number of sand piles 2 are connected by the cracks 13 and 14 to form a water path, which facilitates the diffusion of the purifying agent (see FIG. 3).

Next, the injection well 3 is formed in the sand pile 2. The injection well 3 is a well for injecting a purifying agent into the sand pile 2. The injection well 3 is built into all sand piles or some sand piles by intrusion or rotation. As a result, a purifying agent injection pipe (not shown) whose end is connected to the purifying agent storage tank is connected to the injection well 3. As a result, the purifying agent can be injected from the purifying agent injection pipe into the injection well by pumping (FIGS. 5 and 6). The injection well having a large number of through holes formed on the peripheral surface of the tubular body is preferable because it can supply the purifying agent over the entire length.

The purifying agent injected into the injection well 3 permeates into the sand pile 2 and also permeates the cracks 13 and 14 communicating with the sand pile 2. Further, when the injection well 3 is formed in a part of the sand piles 2, the sand pile 2 in which the injection well 3 is not formed communicates with the sand pile 2 in which the injection well 3 is formed due to a crack. Even in this case, the purifying agent permeates all the sand piles 2 and permeates the cracks 13 and 14 connected to the purifying agent. As a result, the contaminants in the cracks 13 and 14 are purified.

Further, as a modification of the method for purifying the weathered rocky ground in the first embodiment, a pumping well may be attached to the weathered rocky ground and a circulation method may be used in which the pumping well and the injection well are connected. That is, in the weathered rocky ground, the sand pile in which the injection well is formed and the pumping well are connected by a crack, and the pumping water containing the purifying agent pumped from the pumping well is, for example, a purifying agent concentration adjusting tank on the ground. At, the purification agent concentration is adjusted and injected into the injection well. As a result, the purification period can be shortened. In the circulatory system connecting the pumping well and the injection well, the installation of the purifying agent concentration adjusting tank can be omitted.

Next, the method for purifying the weathered rocky ground in the second embodiment of the present invention will be described with reference to FIG. 7. In FIG. 7, the same components as those in FIGS. 1 to 6 are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described. That is, the difference between the method for purifying the weathered rocky ground in the second embodiment and the method for purifying the weathered rocky ground in the first embodiment is that the infiltration well 4 is installed instead of the injection well 3. It is a point.

That is, the infiltration box 4 is installed on the upper part of the sand pile 2 formed in the weathered rocky ground. The infiltration box 43 infiltrates the purifying agent into the sand pile 2. The infiltration box 4 is, for example, a cylindrical frame body having substantially the same diameter as the sand pile 2 and having no bottom plate and top plate, and is simply placed on the upper part of the sand pile 2. The infiltration box 4 contains a purifying agent, and the purifying agent permeates the sand pile 2 due to the natural gravity drop. A filter that limits the permeation rate of the purifying agent may be installed at the portion (for example, the bottom) of the permeation box 4 that communicates with the sand pile 2.

The purifying agent that has penetrated into the sand pile 2 is stored in the gaps between the sand particles in the sand pile 2. As a result, the head can be kept constant and the purifying agent can be infiltrated by gravity. Then, the purifying agent that has penetrated into the sand pile 2 also penetrates into the cracks 13 and 14 that communicate with the sand pile 2. As a result, the contaminants in the cracks 13 and 14 are purified. Further, when the infiltration box 4 is installed in a part of the sand piles 2, the sand pile 2 in which the infiltration box 4 is not formed communicates with the sand pile 2 in which the infiltration box 4 is formed by the crack. Even in this case, the purifying agent permeates all the sand piles 2 and permeates the cracks 13 and 14 connected to the purifying agent. The method for purifying the weathered rocky ground in the second embodiment has the same effect as the method for purifying the weathered rocky ground in the first embodiment.

The present invention is not limited to the above embodiment, and various modifications can be taken. As a method for forming the sand pile, in addition to the one in which the plan view as shown in FIGS. 4 and 5 is formed at the intersection of the grids, the intersection of the triangular eyes, the intersection of the irregular shapes, and the like may be used. Further, the depth of the injection well is not particularly limited and may be half or less of the length of the sand pile. Even if the length of the injection well is short, the purifying agent can be supplied over the entire length of the sand pile by infiltration. The infiltration box may be installed on a sand stake with a purifying agent contained therein, or may be charged with a purifying agent in a state of being installed on a sand stake.

Further, as a method of forming a granular material pile on the weathered rocky ground, in addition to the above-described embodiment, a method of drilling a hole with a boring machine and then throwing the granular material into the drilling, a method of forming a granular material into the drilling, and a weathered rocky ground. It is also possible to use a method in which a casing is placed, rock content in the casing is removed, and a granular material is put into the casing.

In the present invention, the granular material pile constructed in step I, the granular material pile in which the injection well is formed, and the infiltration box installed in step II are formed so that the upper surface thereof is connected to the ground surface such as rainstorm, which causes rainfall. It is preferable in that it can be actively infiltrated into the weathered rocky ground and purification can be promoted by washing with water while diluting.

According to the present invention, the contaminated weathered rocky ground can be efficiently purified, so that it is possible to use the ruins, which was difficult in the past.

1 Ground surface 2 Sand pile (granular pile)
3 Injection well 4 Infiltration box 11 Sand, gravel layer 12 Weathered rocky ground 13 Crack 14 New crack

Claims (8)

A method of purifying contaminated weathered rocky ground,
Step I to form a large number of granular material piles connected by cracks that become water paths in the weathered rocky ground, and either the granular material or the granular material piles are impregnated with a purifying agent, or the granular material piles are watered. A method for purifying weathered rocky ground, which comprises the II step of injecting. The method for purifying weathered rocky ground according to claim 1, wherein the granular material is one or more selected from sand, crushed stone, glass beads and resin beads. The weathered rock according to claim 1 or 2, wherein in the step I, a hollow pipe is penetrated and pulled out into the weathered rocky ground by vibration or rotation, and a granular material pile is formed from the granular material in the hollow pipe. How to purify the quality ground. Claim 1 is characterized in that, in the step I, a weathered rocky ground is drilled, and then a fluidized granular material is injected into the drilling by press fitting to form a granular material pile in the drilling. Or the method for purifying weathered rocky ground according to 2. The II step is any one of claims 1 to 4, wherein an injection well is installed in the granular material pile and a purifying agent is injected from the injection well, or water is injected from the injection well. The method for purifying weathered rocky ground described in the section. The method for purifying weathered rock ground according to claim 5, wherein the water is circulating water from a pumping well formed in the weathered rock ground. The II step is any one of claims 1 to 4, wherein a permeation box containing a purifying agent is installed on the upper part of the granular material pile, and the purifying agent is permeated from the permeation box into the granular material pile. The method for purifying weathered rocky ground according to item 1. The II step is a step of impregnating the granular material with a purifying agent, first performing the II step, then carrying out the I step using the granular material containing the purifying agent as a pile material, and containing the purifying agent. The method for purifying weathered rocky ground according to claim 1 or 2, wherein a granular material pile is formed.

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