JP2000104066A - Water stop agent for ground and method for water stop of ground - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water stop agent not polluting subsurface water and being injectable into fine sandy ground by using a plurality of aqueous solutions which form insoluble precipitates when mixed with each other. SOLUTION: The voids in ground is filled separately with at least two aqueous solutions which form insoluble precipitates when mixed with each other, namely, a first aqueous solution having a concentration of 5 wt.% to the saturation solubility and a second aqueous solution having a concentration of 2 wt.% to the saturation solubility. The order of injection is not particularly limited and simultaneous injection is also possible so far as the form of injection permits the full penetration of the solutions into the voids in ground and their subsequent mixing. The first aqueous solution is exemplified by an aqueous solution of a calcium salt such as calcium chloride or calcium nitrate, a magnesium salt such as magnesium chloride or magnesium sulfate, or an iron salt such as iron sulfate or iron chloride. The second aqueous solution used is exemplified by an aqueous solution of a carbonate such as sodium carbonate or potassium carbonate or a bicarbonate such as sodium bicarbonate or potassium bicarbonate. It is desirable that the precipitated insoluble precipitates are made from calcium carbonate, magnesium carbonate, or iron carbonate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproofing agent for a ground for filling cracks and voids in the ground and a method for stopping the ground for preventing spring water and improving soft ground (reducing water permeability). It is.

[0002]

2. Description of the Related Art Conventionally, as a material to be injected into cracks and voids in the ground for preventing spring water and improving soft ground, a suspension-type injection material in which an inorganic material-based powder is dispersed in water, and water glass are used. Injections, asphalt emulsions, polymer compounds, and the like, which are the main components, are used.

[0003]

Among the conventional injection materials, the injection agent containing water glass as a main component has a high permeability to the ground, but has a high pH, so that there is a problem of groundwater contamination, so that it is not used. Limited. Asphalt emulsions and high molecular compounds also have high permeability to the ground, but their use is also limited because organic substances elute and contaminate groundwater.

On the other hand, in the case of a suspension-type injection material in which an inorganic material-based powder is dispersed in water, there is no problem of groundwater contamination, but a particle diameter of 1 m
When it is injected into a sandy ground or the like composed of particles having a particle size of m or less, there is a disadvantage that it cannot be used because of poor permeability. That is, particle size 1m
If an attempt is made to inject a suspension containing powder into a sand ground made of fine particles of m or less, the solid content in the powder is clogged between the sand particles, making it difficult to inject the suspension thereafter.

[0005] For these reasons, the injection agent cannot be used for the fine-grained sandstone layer, and the ground improvement and the ground reinforcement cannot be performed in many cases.

The present invention solves the above-mentioned conventional problems, has no problem of groundwater contamination, and has excellent permeability and can be easily injected into fine-grained sand ground. An object of the present invention is to provide a method for stopping water in the ground using the water stopping agent.

[0007]

According to the present invention, there is provided a ground water stopping agent comprising two or more aqueous solutions which form an insoluble precipitate upon mixing.

[0008] The method for stopping water in the ground according to the present invention is characterized by separately injecting two or more aqueous solutions each of which forms an insoluble precipitate by mixing.

In the present invention, since the aqueous solution is injected into the ground, it can be injected with good permeability even in fine-grained sand ground. The injected aqueous solution is mixed in the void in the ground to form an insoluble precipitate, that is, a solid, and the solid is filled in the void to stop water.

[0010] In the present invention, since the produced solid is used to fill the voids in the ground to stop water, the produced matter may be a solid, and need not be a cured product.

In the present invention, it is particularly preferable to use an aqueous solution of a calcium salt and an aqueous solution of a carbonate and / or a hydrogen carbonate, and it is preferable to fill the voids with the calcium carbonate generated thereby.

[0012]

Embodiments of the present invention will be described below in detail.

In the present invention, two or more aqueous solutions which form an insoluble precipitate upon mixing,
Each type of aqueous solution is separately filled into the space of the ground. The two types of aqueous solutions that produce an insoluble precipitate upon mixing include a calcium salt aqueous solution, a magnesium salt aqueous solution, or an iron salt aqueous solution (referred to as a “first aqueous solution”) and a carbonate and / or bicarbonate aqueous solution. (Referred to as "second aqueous solution"), to form calcium carbonate, magnesium carbonate or iron carbonate as an insoluble precipitate.

In the first aqueous solution, it is preferable to use one or more of calcium chloride, calcium nitrate and calcium acetate as the calcium salt of the aqueous calcium salt solution. It is preferable to use one or more of magnesium sulfate, magnesium chloride, magnesium nitrate, and magnesium acetate. The iron salt of the aqueous iron salt solution may be a ferrous salt or a ferric salt, and may be iron sulfate, iron chloride,
It is preferable to use one or more of iron nitrate and iron acetate.

On the other hand, as the carbonate and / or bicarbonate of the second aqueous solution and / or bicarbonate aqueous solution, one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and potassium bicarbonate are used. It is preferably used.

That is, in the case of the above-mentioned salts, sodium chloride, potassium chloride, sodium nitrate, potassium nitrate, sodium acetate, sodium chloride, potassium chloride, sodium nitrate,
Although it produces potassium acetate, these salts are extremely advantageous in that they are non-toxic and free from soil or groundwater contamination.

In the present invention, when the salt concentration in the first aqueous solution and the second aqueous solution is excessively low, the amount of insolubles generated is small, and a sufficient water stopping effect cannot be obtained. The salt concentration of the aqueous solution is not less than 5% by weight, especially not less than 20% by weight and not more than the saturation solubility, and the salt concentration in the second aqueous solution is not less than 2% by weight, especially not less than 5% by weight and not more than the saturated solubility. Preferably, there is.

As the first aqueous solution, two or more of a calcium salt aqueous solution, a magnesium salt aqueous solution and an iron salt aqueous solution may be used, and two or more of a calcium salt, a magnesium salt and an iron salt may be used. A mixed salt aqueous solution may be used, but in the present invention, it is particularly preferable to use a calcium salt aqueous solution to generate calcium carbonate as an insoluble precipitate.

In the present invention, the first aqueous solution and the second aqueous solution are separately injected without being mixed before the injection, and are mixed with each other in a void in the ground to form an insoluble precipitate. The order of the injection is not limited. In addition, simultaneous injection may be performed as long as the injection mode is such that the water is sufficiently mixed into the space of the ground and then mixed. In addition, the first aqueous solution and the second aqueous solution may be injected from the same location or may be injected from a location about 1 to 10 m apart from each other at the location to be injected into the ground. The injection form is not particularly limited as long as the first aqueous solution and the second aqueous solution are mixed to generate an insoluble compound after sufficiently penetrating into the voids in the ground.

[0020]

The present invention will be described more specifically with reference to the following examples.

Example 1 Liquid A (first aqueous solution) was prepared by mixing 500 g of reagent calcium chloride in 1 L of tap water, and liquid B was prepared by mixing 80 g of reagent sodium carbonate in 0.92 L of tap water. (Second aqueous solution).

A glass tube having a diameter of 40 mm with a cock attached to the lower part is filled with sand having a water permeability of 2 × 10 ⁻³ (cm / sec), and the liquid A is allowed to flow down naturally from the sand. Was allowed to flow naturally from the sand, and then allowed to stand for 48 hours to form a precipitate of calcium carbonate in the sand. After the test, the permeability of the sand was measured.
^-5 (cm / sec), and water was stopped.

[0023]

As described above in detail, according to the water blocking agent for ground and the method for stopping water of the ground of the present invention, the problem of groundwater contamination is not caused, and the permeability of fine ground sand or the like is poor. Water can be effectively stopped even on the ground, and the ground can be improved.

Claims (6)

[Claims] 1. A ground water stopping agent comprising two or more aqueous solutions that form an insoluble precipitate upon mixing. 2. The water stopping agent for ground according to claim 1, comprising an aqueous solution of calcium salt and an aqueous solution of carbonate and / or hydrogen carbonate. 3. The waterproofing agent for ground according to claim 1, wherein the insoluble precipitate is calcium carbonate. 4. A method for stopping water in a ground, comprising separately injecting two or more aqueous solutions each of which produces an insoluble precipitate by mixing. 5. The method according to claim 4, wherein the calcium salt aqueous solution and the carbonate and / or bicarbonate aqueous solutions are separately injected. 6. The method for stopping water in a ground according to claim 4, wherein the insoluble precipitate is calcium carbonate.