JPS6018709B2 - Chemical injection waterproofing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a construction method used in civil engineering construction, in which a chemical solution is injected into gaps in a ground structure made up of soil particles to block water.

In the old method, the chemical solution itself is diluted by water in the ground, resulting in a decrease in concentration, and in the ground where there is a lot of underground water flow, the chemical solution may be washed away from the target ground to other sources before it solidifies. It has the disadvantage that it cannot produce the effects of water.

The present invention makes it possible to easily and reliably inject a chemical solution into a predetermined position in the ground, and also to ensure that water is blocked as expected.Furthermore, the effective water-blocking range of the chemical solution is significantly expanded, and It is possible to increase the resistance to spillage of chemical liquid,
Therefore, it is an object of the present invention to provide a chemical liquid injection waterproofing construction method that can be constructed with extremely high reliability even on the ground to which conventional construction methods cannot be applied.

The chemical injection waterproofing method of the present invention is applied to civil engineering construction, and in order to waterproof the ground made of soil particles, isocyanate or a chemical containing isocyanate as a main component and having a solidification promoting catalyst is applied to the ground. It is injected directly into the gaps between soil particles in the area to be water-blocked, and the reaction between the chemical and water generates a gel substance and carbon dioxide gas between the soil particles. By trapping carbon dioxide gas in the form of bubbles in the gel material, the pressure generated by the carbon dioxide gas is actively utilized to increase the permeability of the chemical solution into the ground during the gel material generation process, thereby expanding the permeation range. It is characterized by intervening the gel material with a multicellular structure containing carbon dioxide gas bubbles in the gaps between soil particles in the ground to block water, and has the following advantages. be.

In other words, it facilitates penetration into the ground and uses the water in the ground for a water-blocking reaction. By actively utilizing the reaction product gas, it expands and infiltrates into the interstitial spaces of the ground in a sufficiently reliable manner in the form of multiple bubbles, thereby systematically achieving the desired water-shielding effect at the desired underground location. It will be carried out. In addition, an extremely simple device for injection is sufficient; for example, a simple piston-type hand pump can be used to locally inject concentrated water to immediately block water. Therefore, the present invention is completely different in principle from the conventional chemical injection waterproofing method in terms of the diffusion and solidification mechanism of the chemical used, and therefore cannot be achieved by the known waterproofing method by underground chemical injection. This invention is new and has great industrial value, as it can successfully achieve a water-blocking effect that has previously been difficult to achieve.

In particular, in the present invention, an isocyanate compound used as a chemical solution that causes a chemical reaction in contact with pore water in the ground is directly injected into the gaps between soil particles in an area to be water-blocked, and then comes into contact with pore water in the ground. During polymerization, the pressure of carbon dioxide gas that is rapidly released due to the presence of a solidification promoting catalyst and gas bubbles are actively used to temporarily eliminate excess water around the solidified ground and solidify rapidly. It integrates with the entire ground into which the chemical solution has been injected, and quickly forms an interface that prevents water from entering, thereby making it possible to prevent the chemical solution from being washed away by underground water flow and to further ensure the water-blocking effect. The chemical solution applied to the present invention is R-(NCO)m
These compounds are a group of substances that react with water, generate carbon dioxide gas, and polymerize to form a gel-like polymer that is insoluble in water.

Incidentally, R represents an aliphatic or aromatic group, or an organic group containing both, and m is an integer of 1 or more. However, those that are easy to obtain and put to practical use are numbers 2 to 6. Typical materials that can be used in the present invention include polyols containing active hydrogen such as polyester glycol or polyether glycol, prepolymers derived from diisocyanate and having isocyanate groups at the ends, tolylene diisocyanate, methylene bis Aromatic or aliphatic polyisocyanates such as P-phenylene diisocyanate, 1,6-hexamethylene diisocyanate, polyarylene polyphenylisocyanate, and the like.

In general, isocyanate compounds polymerize and solidify when they come into contact with water, and release carbon dioxide gas when reacting with water. Therefore, when isocyanate compounds are injected into the ground gap located in three-dimensional space, the isocyanate compounds will solidify in the ground. When it comes into contact with the water inside, a polymerization reaction occurs and a gel-like polymer solidified substance that does not fall off is produced in the pores of the ground, increasing the water-blocking effect. It has the effect of temporarily eliminating excess water around the area and expanding the effective water-shielding range of the chemical solution, so it can provide a good water-shielding effect even on harsh water-bearing ground. be.

Furthermore, by adding an appropriate amount of tertiary amines or organometallic compounds such as dibutyltin laurate to these isocyanate compounds as a solidification promoting catalyst, a polymerization solidification reaction accompanied by carbon dioxide gas generation due to contact between the isocyanate compounds and water can be carried out. can be carried out more rapidly, and the ground can be immediately effectively blocked from water.

In addition, by adding a diluent to the isocyanate compound, a diluent consisting of a hydrophobic or hydrophilic or halogen-containing organic solvent such as benzol, xylol, toluene, acetone, methyl ethyl ketone, ethyl acetate, trichloroethylene alone or in combination, By lowering the viscosity of the isocyanate compound, it is possible to sufficiently and reliably penetrate the isocyanate compound into the ground made of pongee grain, which has poor permeability. Furthermore, in order to control the hydration reaction rate or the stability of carbon dioxide gas bubbles, it is also possible to mix the isocyanate compound with a surfactant and inject it into the soil. It is necessary to use a substance that does not chemically react with isocyanate compounds that contain active hydrogen in their molecules, such as surfactants.

Examples of the results obtained by injecting the chemical solution described above into the ground are as follows.

Example 1 A model ground consisting of a sand layer in which the water flow gradient could be freely adjusted was prepared, and four typical types of commercially available water-soluble grouts and the present invention were mixed under the conditions shown in Table 1 below. We attempted a comparative injection experiment with a isocyanate-based prepolymer.

The isocyanate prepolymer used in this experiment was polypropylene glycol lylene diisocyanate (2.
4/2. Parts by weight of xylol 3 were added to parts by weight of bifunctional urethane prepolymer 7 with a mirror-mineral ratio = 80/20), and the solvent was removed, and then 0.1% of the total amount of silicone surfactant (Union Silicone L-*5320 (manufactured by Carbide Co., Ltd.) and 0.5% triethylamine added as a curing accelerating catalyst. Table HI Experimental Conditions The experimental results are shown in Tables 2 to 4. In particular, the isocyanate prepolymer according to the present invention was very effectively expanded and consolidated on the ground under moving water.

Table-2. Experimental results (Experiment 1) Table 3 for sand with particle size 0.3-0.6 (n = 40.0%)
38.0%) sand (Experiment 2) Table 4 Experimental results for sand with particle size 1.2 to 2.5 (NI37.5%) (Experiment 3) Example 2 Particle size 0.6 ~1.2 Create a sandwich-like model ground with a sand layer sandwiched between upper and lower impermeable clay layers, and use four typical commercially available water-soluble grouts and the present invention under the conditions shown in Table 5 below. An experiment was conducted to compare the consolidation and water-stopping effect of sand layers with isocyanate-based prepolymers.

The isocyanate prepolymer used in this experiment was polypropylene glycol trilene diisocyanate (2.
4/2.6 isomer ratio = 80/20) 1 part by weight of acetone and 2 parts by weight of xylene were added to 7 parts by weight of bifunctional urethane prepolymer (isomer ratio = 80/20), the solvent was removed, and 0.2 parts by weight were added as a curing accelerating catalyst. % of triethylene diamine was added. Table 5 Experimental conditions The experimental results are shown in Table 6. In particular, only the isocyanate-based prepolymer according to the present invention expands and solidifies in a multifoamed shape that can completely block running water, resulting in water reduction rate. It showed a value of 100%.

Table 6 Water stoppage experiment results Water reduction rate i÷TempleX・oo a: Water flow rate per unit time before injection b: Water flow rate per unit time after injection Example 3 Lm x Width lm x Height 1 skin A model ground was created by filling an iron container with a drainage hole in the bottom with river sand that had been divided into grain sizes of 1.2 to 2.5 and tamping it down with water.

An injection pipe made of hard vinyl chloride with an inner diameter of 3/4 inch and a closed end was set vertically at a depth of 50 skin from the center of the surface of the model ground, and an air-driven injection pump was used from the injection pipe. Two types of isocyanate-based prepolymers and four types of commercially available typical water-soluble grouts were separately injected in 10 doses. The conditions of the model ground and the injection conditions of each grout are shown in Table 7.

The compacted soil blocks were taken out 24 hours after the injection, and the volume and compressive strength of each compacted soil block were measured.

As the isocyanate-based prepolymer, polypropylene glycol lylene diisocyanate (2.4/2
．． 1 part by weight of acetone and 2 parts by weight of xylene were added to 1 part by weight of acetone and 2 parts by weight of xylene to parts by weight of bifunctional urethane prepolymer 7 with a winged body ratio of 80/20), and 1 part by weight of triethylamine as a reaction accelerator was added. [A] prepared by mixing [A], and a nonionic surfactant (manufactured by Daiichi Kogyo Seiyaku KK) for the purpose of improving the permeability to the ground and further increasing the volume of the solidified mass. ) Prepared by mixing 2 parts by weight of Agen EA) [B]
Two types were used. After measuring the volume of the compacted soil mass using the water displacement method, a cube with dimensions of 10 cm x 10 cm x 10 cm was carefully collected from near the center of each compacted soil mass using a hacksaw. An unconfined compressive strength test was conducted on a material capped with gypsum.

The test results are shown in Table 8, and it was found that when the isocyanate prepolymer of the present invention was used, the volume and unconfined compressive strength of the compacted soil mass were particularly superior compared to other commercially available grouts. Furthermore, it has been found that among the isocyanate-based prepolymers according to the present invention, when a surfactant is used in combination, there is an effect of further increasing the volume of the compacted soil, and the decrease in strength is relatively small. From this, it can be understood that the produced material is not easily destroyed by external stress, and the water-blocking state is strongly maintained even in the presence of external stress. Table 7 Model ground conditions and grawat injection conditions Table 8 Test results The ☆ mark in the table indicates that the compacted soil mass was extremely brittle and test pieces could not be collected. A cylindrical iron pressure-resistant container with a cock on the bottom lid and a pressure gauge on the top lid is prepared. First, with the top lid removed, river sand divided into 2 to 4.75 pieces is placed inside the container. After filling the sand to its fullest and filling the gaps in the river sand with water from the surface of the sand, open the cock on the bottom lid to remove the water in the gaps.

After closing the cock again, pour the isocyanate prepolymer [A] used in Example 3 from the top until it fills the gaps in the river sand in the container and overflows from the top.
Immediately attach the upper lid equipped with a pressure gauge, and from then on
As a result of measuring the pressure of carbon dioxide gas generated during the hydrolysis reaction of the isocyanate prepolymer at room temperature, the pressure showed a pressure of 38.4 k9/kg after about 30 minutes. This proves that the isocyanate-based prepolymer according to the present invention captures pore water in the ground by itself and when polymerizing and solidifying, it further expands the solidification range while eliminating surrounding excess water. . Furthermore, the following experiment was attempted to confirm the solidification effect of monoisocyanate compounds. Example 5 Commercially available phenyl isocyanate (C6day5・NCO
) and 0.5 parts by weight of triethylamine as a curing accelerating catalyst.
Add 1.5 parts by weight of tap water to 0 parts by weight, add it to the moist sample soil, mix well, and immediately prepare a 4 x 4 x 16 lotus type for cement strength test specified in JISR-5201. A strength test was conducted on 3 pieces of compacted material that were filled into a frame, molded, removed from the mold after 24 hours, and cured in the air for 6 days.The average compressive strength was 10.2k9/ground. The average bending strength was 4.1k9'.

Furthermore, the following test was conducted to confirm the soil consolidation effect of newly synthesized monoisocyanate.

Example 6 Contents 1 Each of the round-bottomed 4-neck reaction flasks was equipped with a mercury thermometer, a Nada Western clothing layer, a cooling tube (also used as a nitrogen gas introduction tube), and a dropping funnel, and a trifluorocarbon purified by distillation was placed in the flask. Isocyanate (2.4/2.Tsubaoi body ratio=8
0/20) Put 34 parts by weight in a box and 6 parts by weight in a nitrogen gas atmosphere.
While maintaining this temperature, 260 parts by weight of 2-ethylhexyl alcohol (equimolar to the tolylene diisocyanate) was introduced from the dropping funnel over about 2 hours.

After the introduction of 2-ethylhexyl alcohol, the reaction was continued for another 3 hours while maintaining the temperature of 60 qo. As a result, a liquid monoisocyanate with an NCO concentration of 13.6% was obtained, which had a pale yellow transparent appearance and was viscous steel. Ta.

For each part by weight of this reaction product, 1 xylol is added.
Dilute by adding 0 parts by weight, and further add 0 parts by weight to this total amount.
A chemical solution was prepared by adding and mixing 1 part by weight of a silicone surfactant (manufactured by Union Carbide, Silicone L-5320) and 0.5 parts by weight of triethylamine as a curing accelerating catalyst, and mixed with 300 parts by weight of Toyoura standard sand. Tap water for 15 minutes
Parts by weight of the above chemical solution 5 were added to the mixture to make it moist, and the mixture was mixed well. Immediately it was filled into the same Sanren mold for cement strength test as in Example 5, and after 24 hours it was removed. After molding, we further cured in the air for 6 days and conducted a strength test on the 3 pieces obtained. As a result, we obtained an average compressive strength of 23.3k9' and an average bending strength of 9.3 x 9cm. Ta. From the test results of Examples 5 and 6, a considerable consolidation effect was observed in both cases. However, this type of low molecular weight monoisocyanate, particularly the phenyl isocyanate used in Example 5, may be subject to practical limitations from the viewpoint of odor and strength properties of caking agents.

Claims (1)

[Claims] 1. When carrying out civil engineering and construction work to make the ground made of soil particles waterproof, it is necessary to apply isocyanate or a chemical solution containing isocyanate as a main component and having a catalyst to promote solidification to the soil in the area to be water-blocked. The chemical solution is injected directly into the interstices of the soil particles, and a gel substance and carbon dioxide gas are generated between the soil particles by the reaction between the chemical solution and water, and in the process of producing the gel substance, carbon dioxide gas is bubbled into the gel substance. The pressure of the carbon dioxide gas generated is actively used to increase the permeability of the chemical solution into the ground during the process of forming the gel substance, expand the permeation range, and eliminate the carbon dioxide gas bubbles. A chemical liquid injection water-blocking construction method characterized in that the gel material with a multi-foam structure is interposed between the gaps between soil particles in the ground to block water.