JP2022023206A - Water-reducing natural ground improvement material and natural ground stabilization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow achieving reduction of cost for materials while securing cutoff water-reduction effects or natural ground improvement effects.

SOLUTION: There is provided a water-reducing natural ground improvement material having cutoff water-reduction effects or natural ground improvement effects by filling the same in a rock mass or natural ground, consisting of an urethane-based cutoff material, having physical properties expanding even in contact with water, or in no contact with water, expansion ratio in the case in contact with water and expansion ratio in the case in no contact with water are preferably at least 3 times or more respectively, or the expansion ratio in the case in contact with water and the expansion ratio in the case in no contact with water are preferably almost same.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a water-reduced ground improvement material and a ground stabilization method.

Conventionally, it is known that an injection material made of urethane-based silica resin is used when stabilizing and strengthening unstable rock or ground in a mountain tunnel or the like. In this case, when there is a large amount of spring water, the injection material flows out together with the water, and the water reduction effect cannot be expected.

On the other hand, as an injection material for the purpose of stopping water and reducing water, for example, Patent Document 1 describes an injection chemical composition for stabilizing soil such as a polyol and / or an organic polyamine compound, an organic polyisocyanate compound, and water. Is disclosed. However, since the chemical solution composition described in Patent Document 1 has a high foaming ratio, it does not have sufficient strength, and it is possible to completely stop water against a large amount of water leakage or spring water. It could have been difficult.

On the other hand, as an injection material for long-term water stoppage against a large amount of water leakage or spring water, for example, as shown in Patent Document 2, the polyol contains a polyether polyol, and the amine compound is first-class. Alternatively, an injectable drug solution composition containing an amine compound having a secondary amino group is disclosed. In this case, it has sufficient strength to stop a large amount of water leakage and spring water, does not become cloudy when it comes into contact with water, does not adversely affect the environment, and has a small foaming ratio. That is, when the foaming ratio when the chemical and water come into contact with each other is large, the volume of the foam that flows out together with water leakage or spring water becomes large, and there is an advantage that adverse effects on the environment can be prevented.

Japanese Unexamined Patent Publication No. 7-262363 JP-A-2015-117304

However, the conventional injection material has the following problems.
That is, in the case of the injection material of Patent Document 2, the purpose is to stop water for a long period of time, and when spring water is generated from the ground, the water reduction effect is gradually reduced while forming a foamed solid body in contact with water. By increasing and continuously injecting, at the final stage, a non-foaming zone that does not come into contact with water is formed, and a reliable water-stopping and water-reducing effect is exhibited. In this case, the water-stopping and water-reducing effect in a large amount of spring water is high, and the strength at the time of no foaming is high, so that the water-stopping water-reducing effect can be obtained even under the condition of high-pressure spring water.

However, in the case of a mountain tunnel, for example, there are many cases where a part with spring water and a part without spring water are mixed in the cross section. Therefore, if there is a part where there is no spring water, the injection amount is determined assuming that there is no spring water in the entire cross section. The injection amount is determined by setting 1 to 1, and the injection amount tends to increase. Moreover, the injection material having physical properties as in Patent Document 2 is expensive, and there is a problem that the cost increases as the injection amount increases.
Therefore, there is a current situation in which it is not possible to achieve a good balance between the problem of increased material cost, water stoppage and water reduction, and stabilization of the ground, and there is room for improvement in that respect.

The present invention has been made in view of the above-mentioned problems, and is a water-reducing ground-improving material and a ground that can reduce the cost of materials while ensuring the water-stopping water-reducing effect and the ground-improving effect. The purpose is to provide a stabilization method.

In order to achieve the above object, the water-reducing ground improvement material according to the present invention is a water-reducing ground improvement material having a water reduction effect and a ground improvement effect by filling the bedrock or the ground, and is a urethane-based water blocking material. It is a physical property that foams even if it is in contact with water or not in contact with water. The composition of the liquid A and the liquid B as the main component is 1 part by weight of the liquid A and 0.9 to 1.1 parts by weight of the liquid B, and the liquid A has a viscosity at a temperature of 25 ° C. Liquid B has a viscosity of 150 to 250 mPa · s at a temperature of 25 ° C. and a specific gravity of 1.20 to 1 at a temperature of 20 ° C. It is .26, and is characterized in that the foaming ratio when in contact with water and the foaming ratio when not in contact with water are 6 to 10 times, respectively.

Further, the stability strengthening method according to the present invention is a ground stabilization work for filling the bedrock or the ground by using a water-reducing ground improvement material having a water reduction effect and a ground improvement effect by filling the bedrock or the ground. According to the method, the water-reducing ground improvement material is made of a urethane-based water-stopping material, and has a physical property of foaming even if it is in contact with water or not in contact with water. Is mainly composed of a liquid A made of a polyol catalyst and a liquid B made of polyisocyanate, and the composition of the liquid A and the liquid B is such that the liquid A is 1 part by weight and the liquid B is 0.9 to 1. It is 1 part by weight, and the foaming ratio is 6 to 10 times when it is in contact with 1% water and when it is not in contact with water, and the liquid A has a viscosity of 150 to 350 mPa · s at a temperature of 25 ° C. The liquid B has a viscosity of 150 to 250 mPa · s at a temperature of 25 ° C. and a specific gravity of 1.20 to 1.26 at a temperature of 20 ° C. The water-reduced ground improvement material is characterized in that it is injected into a bedrock or a ground so that the injection pressure is 0.5 MPa or more and the initial injection pressure is 0.7 MPa or more.

In the present invention, the water-reduced ground improvement material foams when it comes into contact with water and also foams even when it does not come into contact with water. It also has a water reduction effect such as workability in construction work and suppression of the decrease in groundwater level. That is, when the water-reducing ground improvement material of the present invention is injected into a defective ground, the water-reducing effect can be gradually enhanced while contacting with spring water to form a foamed consolidated body. Therefore, by continuously injecting the water-reducing ground improvement material, it is possible to form a weak foam zone and reduce the water to the extent that it does not hinder the work of tunnel excavation.

In addition, even in a place with complicated ground conditions where spring water is partially generated, or in a place where there is no spring water, it is possible to have a certain degree of foaming, so injection is possible. It is possible to secure the ground permeability of the water-reducing ground improvement material, and as described above, the water-stopping water-reducing effect and the ground-improving effect can be effectively exhibited at the same time. Therefore, even under the condition of a large amount of spring water or high-pressure spring water, the water-reducing ground improvement material to be injected foams to stop or reduce the water content.
As described above, since the water-reducing ground improvement material of the present invention foams even when it is not in contact with water, the total injection amount is larger than that in the case of injecting a material that does not foam when it does not come into contact with water. It can be reduced and the material cost can be reduced.

Furthermore, in the present invention, the consolidation strength of the water-reduced ground improvement material can be suppressed to be smaller than the consolidation strength of the non-foaming injection material by foaming. Therefore, high-pressure injection becomes unnecessary, the burden on the injection equipment used for injection can be reduced, and general-purpose equipment can be used. For example, equipment for ultra-high voltage becomes unnecessary, and cost can be reduced.

Further, in the present invention, the foaming ratio when in contact with water does not become excessively large as compared with the foaming ratio when not in contact with water, and it is possible to suppress a decrease in the improved strength during foaming.

Further, in the present invention, in the case of a mountain tunnel, even under the condition of overburden where the water pressure is as high as 0.5 MPa or more, the water-reducing ground improvement material of the present invention is filled in the bedrock or the ground. The stabilization method can be applied.

According to the water-reducing ground improvement material and the ground stabilization method of the present invention, it is possible to reduce the cost of the material while ensuring the water-stopping water-reducing effect and the ground improving effect.

It is a partially broken vertical sectional view which shows the structure of the test apparatus according to the Example of this invention.

Hereinafter, the water-reduced ground improvement material and the ground stabilization method according to the embodiment of the present invention will be described with reference to the drawings.

The water-reducing ground improvement material of the present embodiment is a water-reducing ground improvement material having a water reduction effect and a ground improvement effect by filling the bedrock or the ground. The water-reducing ground improvement material is made of a urethane-based water blocking material, and has a physical property of foaming even if it is in contact with water or not in contact with water.

As the water-reducing ground improvement material, for example, the composition described in the patent document of JP-A-2015-117304 can be adopted. That is, as an example of the water-reducing ground improvement material, an injectable drug solution composition containing a component (A) containing a polyol and an amine compound and a component (B) containing an isocyanate compound, which is substantially free of water. Therefore, an injectable drug solution composition may be used in which the polyol contains a polyether polyol (a1) and the amine compound contains an amine compound (b1) having a primary or secondary amino group.
In the water-reducing ground improvement material of the present embodiment, the component (A) and the component (B) are mixed at an appropriate mixing ratio at the time of use to form a cured product.

The gel time of the water-reduced ground improvement material when the component (A) and the component (B) adjusted to 20 ° C. are mixed is 30 to 90 seconds (60 ± 30 seconds) regardless of the presence or absence of water contact. It is preferably 45 to 75 seconds (60 ± 15 seconds), and more preferably 45 to 75 seconds (60 ± 15 seconds).

The foaming ratio of the water-reduced ground improvement material is preferably at least 3 times or more in the case of contact with water and the case of non-contact with water. The foaming ratio of the cured product is preferably low, for example, about 8 times, in order to reduce the adverse effect on the environment when the cured product flows out due to water leakage or spring water. Here, in the present embodiment, the foaming ratio is a value calculated by dividing the volume of the cured product after the completion of the curing reaction by the volumes of the components (A) and (B) as raw materials. .. The foaming ratio in contact with water is measured by mixing the component (B) with 100 parts by mass of the component (A) plus 1 part by mass of water and foaming.
Further, it is more preferable that the foaming ratio of the water-reduced ground improvement material is substantially the same in each case of contact with water and non-contact with water (8 times in each of the examples described later). ..

Further, the compressive strength of the cured product in the water-reduced ground improvement material is preferably 20 MPa or more from the viewpoint of preventing water leakage and outflow of spring water. The compressive strength of the cured product is a state in which a predetermined amount of the component (A) and the component (B) mixed as they are without adding water is injected into a mold of φ50 mm × 100 mm, covered with a lid, and restrained. A test piece having a diameter of 50 mm × 100 mm is prepared by foaming and curing with, and measured with an Instron universal testing machine in accordance with JIS A1216.

Further, in the present embodiment, it is preferable that the injection pressure of the water-reduced ground improvement material is set to 0.5 MPa or more. As a result, in the case of a mountain tunnel, even under the condition of overburden where the water pressure is as high as 0.5 MPa or more, the water-reducing ground improvement material of the present embodiment is filled in the bedrock or the ground to stabilize the ground. The law can be applied.

In the water-reducing ground improvement material and the ground stabilization method according to this embodiment, for example, when excavating a tunnel, a urethane-based injection type fore polling is performed for the purpose of preventing the top end of the face from collapsing and preventing the expansion of looseness. In the construction method or injection type long tip receiving method (AGF construction method), stabilization / strengthening by consolidation of rocks with crush zones and unstable soft ground, stabilization by filling voids between the ground and concrete segments, etc. Reinforcement, stabilization / strengthening by sealing cavities such as earth and sand, rocks, bricks, coal, repairing cracks in artificial structures such as concrete, stabilization / strengthening by reinforcement, and bedrock with water leaks and springs It is injected into rock or ground and consolidated for water stoppage and water reduction due to application to the ground.
The method of injecting the water-reduced ground improvement material is not particularly limited. For example, a plurality of holes are drilled in the bedrock or the ground at predetermined intervals, hollow bolts are inserted into these holes, and the openings of the bolts are opened. It is possible to adopt a known method of injecting a more water-reduced ground improvement material into the bedrock or the ground and consolidating it.

In the present embodiment, by filling the bedrock or the ground with the water-reduced ground improvement material, the material foams when the water-reduced ground improvement material comes into contact with water and also foams even in a place where it does not come into contact with water. A strong hardened product can be obtained and the ground improvement effect can be exhibited, while a water reduction effect such as workability in mountain tunnel construction and a decrease in groundwater level can be obtained. That is, when the water-reducing ground improvement material of the present embodiment is injected into a defective ground, the water-reducing effect can be gradually enhanced while contacting with spring water to form a foamed consolidated body. Therefore, by continuously injecting the water-reducing ground improvement material, it is possible to form a weak foam zone and reduce the water to the extent that it does not hinder the work of tunnel excavation.

Further, in the present embodiment, it is possible to give a certain degree of foaming even in a place where there is a complicated ground condition where spring water is partially generated, or even in a place where there is no spring water. Since it is possible, the ground permeability of the water-reducing ground improvement material to be injected can be ensured, and as described above, the water-stopping water reduction effect and the ground improvement effect can be effectively exhibited at the same time. Therefore, even under the condition of a large amount of spring water or high-pressure spring water, the water-reducing ground improvement material to be injected foams to stop or reduce the water content.
As described above, since the water-reducing ground improvement material of the present embodiment foams even when it is not in contact with water, the entire injection is performed as compared with the case of injecting a material that does not foam when it does not come into contact with water. The amount can be reduced and the material cost can be reduced.

Furthermore, in the present embodiment, the consolidation strength of the water-reduced ground improvement material can be suppressed to be smaller than the consolidation strength of the non-foaming injection material by foaming. Therefore, high-pressure injection becomes unnecessary, the burden on the injection equipment used for injection can be reduced, and general-purpose equipment can be used. For example, equipment for ultra-high voltage becomes unnecessary, and cost can be reduced.

Further, in the present embodiment, the effect of improving the ground and the effect of reducing water stoppage can be more effectively realized by foaming at a foaming ratio of 3 times or more even if it is not in contact with water. ..

Further, in the water-reducing ground improvement material of the present embodiment, the foaming ratio when in contact with water and the foaming ratio when not in contact with water are substantially the same, so that the foaming ratio when in contact with water becomes water. On the other hand, it does not become excessively large as compared with the foaming ratio in the non-contact case, and it is possible to suppress a decrease in the improved strength at the time of foaming.

As described above, in the water-reduced ground improvement material and the ground stabilization method according to the present embodiment, it is possible to reduce the cost of the material while ensuring the water-stopping water-reducing effect and the ground improvement effect.

Next, an example carried out to support the effect of the water-reduced ground improvement material and the ground stabilization method according to the above-described embodiment will be described below.

(Example)
In this example, in the urethane-based water-reducing ground improvement material of the above-described embodiment, an injection test was conducted under the same test conditions as for spring water, and the water blocking effect and the ground improvement effect were confirmed.
In the test, as shown in FIG. 1, an injection material P (water-reducing ground improvement material) is injected into a tubular test device 1 simulating a tunnel, and the injection amount, water stop state, curing condition, and curing of the injection material P are performed. It confirms the range.

The injection material P used in the test is a comparison between two types of Implementation Cases 1 and 2 using the urethane-based water-reducing ground improvement material according to the above-described embodiment and silica resin (manufactured by "Super SRF" Catex). There are three types with the case. Table 1 shows detailed physical property values of the injection material P in each case. In the first embodiment, the foaming ratio is 3 times when there is no water contact, and the foaming ratio is 8 times when there is water contact (Table 1, Table 2 shown below, and "3-8" in Table 3). Shows). In the second embodiment, the foaming ratio is 8 times when there is no water contact, and the foaming ratio is 8 times when there is water contact (Table 1, Table 2 and Table 3 shown below are "8-8". Shows).

The test apparatus 1 packs the crushed stone 12 into the PVC pipe 11, injects water W composed of tap water into the crushed stone 12 from the inflow port 11a at one end of the PVC pipe 11, and ends the PVC pipe (the side opposite to the inflow port 11a). Water W is discharged from the drainage port 11b (at the end of the water) to reproduce the running water state. As the PVC pipe 11, two PVC pipes having an outer diameter of 76.3 mm and a length of 3 m were coaxially connected, and a pipe having a total length of 6 m was adopted. A variable bypass valve 13 was attached to the inflow port 11a of the water W in the PVC pipe 11, and the water pressure (bypass opening pressure) was set to 0.5 MPa. An injection pipe 14 for mixing and injecting two liquids (liquid A and liquid B) of the injection material P is connected to the intermediate portion in the length direction of the PVC pipe 11, and is injected by a short tube mixer (not shown). The material liquid is injected.
The discharge amount (injection amount) of the injection material P was 5 L / min, and the water injection amount of the water W was 10 L / min. The injection material P and water W to be injected are cooled to around 20 to 25 ° C and 15 ° C, respectively, by a cooling device (not shown).

Table 2 shows the test patterns in three cases (implementation cases 1, 2, and comparative cases). In this test, 10 L / min of water W is injected, and the water stoppage and water reduction effect is confirmed by stopping the flowing water from the drainage port 11b of the PVC pipe 11.
First, the properties of the three types of injection materials P used in the test were confirmed by performing a curing confirmation test. Specifically, as shown in Table 3, it was confirmed that both the curing time and the foaming ratio of each injection material P were within the specifications.

The test results are shown in Table 4. As for the implementation case 2, since the water reduction effect was confirmed when the bypass opening pressure was 0.5 MPa, a test set to 1.0 MPa was also performed.
As shown in Table 4, as a result of the test, it was confirmed that the injection material P (silica resin) in the comparative case flowed out together with the water W and did not stay in the crushed stone 12 of the PVC pipe 11 forming the simulated ground. In this test, the test conditions are such that the injection material P comes into contact with running water immediately after stirring, and it can be presumed that a mixture having a relatively low viscosity before the silica resin starts to cure has flowed out.

On the other hand, in both the injection materials P (3-8, 8-8) of the first and second implementation cases, the injection material P flows downstream from the injection pipe 14 at the injection location together with the flowing water at the initial stage of injection, but the stirred injection material P is the PVC pipe 11. It was confirmed that the water was reduced by staying in the crushed stone 12 and then starting to harden, and it was confirmed that the water was reduced. When the bypass opening pressure is 0.5 MPa, both the injection materials P (3-8, 8-8) of Implementation Cases 1 and 2 are injected until the bypass valve 13 is opened, that is, until water is injected. There was no change in the injection amount of the material P, and there was no change in the injection amount at the time when the water reduction effect was confirmed. It was confirmed that the injection amount was 10 kg in the comparative case, 8 kg in the implementation case 1, and 5 to 6 kg in the implementation case 2, which was about half of the comparative case.
Also, in the case of Implementation Case 2 (8-8) in which the bypass opening pressure was 1.0 MPa, the water reduction effect was recognized, and the injection amount until the bypass valve 13 was opened increased, but when the water reduction was confirmed. The injection amount in was the same as in the case where the bypass opening pressure was 0.5 MPa.

Although the embodiment of the water-reducing ground improvement material and the ground stabilization method according to the present invention has been described above, the present invention is not limited to the above-described embodiment and is appropriately used without departing from the spirit of the present invention. It can be changed.
For example, in the embodiment of the present embodiment, the foaming ratio of the water-reduced ground improvement material is 3 times when there is no water contact and 8 times when there is water contact, and 8 times when there is no water contact. Although the case where there is water contact is shown in 2 cases of 8 times, the foaming ratio is not limited to such. The point is that it may be a water-reducing ground improvement material that is made of a urethane-based waterproof material and that foams even if it is in contact with water or not in contact with water. Further, it is preferable that the foaming ratio when in contact with water and the foaming ratio when not in contact with water are at least 3 times or more, respectively.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present invention.

1 Specimen 11 PVC pipe 12 Crushed stone P Injection material W Water

Claims (2)

It is a water-reducing ground improvement material that has a water-reducing effect and a ground-improving effect by filling the bedrock or the ground.
It is made of urethane-based waterproof material and has the physical characteristics of foaming even if it comes into contact with water or not.
The urethane-based waterproofing material contains mainly liquid A composed of a polyol and a catalyst and liquid B composed of polyisocyanate as main components.
The composition of the liquid A and the liquid B is 1 part by weight of the liquid A and 0.9 to 1.1 parts by weight of the liquid B.
The liquid A has a viscosity of 150 to 350 mPa · s at a temperature of 25 ° C. and a specific gravity of 1.02 to 1.08 at a temperature of 20 ° C.
The liquid B has a viscosity of 150 to 250 mPa · s at a temperature of 25 ° C. and a specific gravity of 1.20 to 1.26 at a temperature of 20 ° C.
A water-reducing ground improvement material characterized in that the foaming ratio when in contact with water and the foaming ratio when not in contact with water are 6 to 10 times, respectively. It is a ground stabilization method that fills the bedrock or the ground by using the water-reducing ground improvement material that has the effect of reducing water and improving the ground by filling the bedrock or the ground.
The water-reduced ground improvement material is
It is made of urethane-based waterproof material and has the physical characteristics of foaming even if it comes into contact with water or not.
The urethane-based water blocking material contains a liquid A made of a polyol catalyst and a liquid B made of polyisocyanate as main components.
The composition of the liquid A and the liquid B is 1 part by weight of the liquid A and 0.9 to 1.1 parts by weight of the liquid B.
The foaming ratios in the case of contact with 1% water and the case of non-contact with water are 6 to 10 times, respectively.
The liquid A has a viscosity of 150 to 350 mPa · s at a temperature of 25 ° C. and a specific gravity of 1.02 to 1.08 at a temperature of 20 ° C.
The liquid B has a viscosity of 150 to 250 mPa · s at a temperature of 25 ° C. and a specific gravity of 1.20 to 1.26 at a temperature of 20 ° C.
The water-reduced ground improvement material is a ground stabilization method characterized by injecting into a bedrock or a ground so that the injection pressure is 0.5 MPa or more and the initial injection pressure is 0.7 MPa or more.

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