JP7347765B2 - Water-reduced ground improvement materials and ground stabilization methods - Google Patents

Description

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

BACKGROUND ART Conventionally, it has been known that injection materials made of urethane-based silica resin have been used to stabilize unstable rock or ground, such as in mountain tunnels. In this case, if there is a large amount of spring water, the injection material will flow out with the water, and no water reduction effect can be expected.

On the other hand, as an injection material for the purpose of water stopping and water reduction, for example, Patent Document 1 discloses an injection chemical composition for stabilizing soil, etc., consisting of a polyol and/or an organic polyamine compound, an organic polyisocyanate compound, and water. is disclosed. However, since the chemical composition described in Patent Document 1 has a high foaming ratio, it does not have sufficient strength and cannot completely stop water from leaking or springing in large amounts. It could have been difficult.

On the other hand, as an injection material that can stop large amounts of water leakage or spring water over a long period of time, for example, as shown in Patent Document 2, the polyol contains a polyether polyol, and the amine compound is a primary Alternatively, an injection drug 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 or spring water, does not become cloudy when it comes in contact with water, does not have a negative impact on the environment, and also has a small foaming ratio. In other words, when the foaming ratio when the medicine and water come into contact is large, the volume of the foam that flows out together with water leakage or spring water increases, which has the advantage of preventing adverse effects on the environment.

Japanese Patent Application Publication No. 7-26263 Japanese Patent Application Publication No. 2015-117304

However, conventional injection materials have the following problems.
In other words, in the case of the injection material of Patent Document 2, the purpose is to stop water over a long period of time, and when spring water occurs from the ground, it gradually reduces water by contacting water and forming a foamed solid. By continuously injecting the foam at a high temperature, a non-foaming zone that does not come into contact with water is formed in the final stage, achieving a reliable water-stopping and water-reducing effect. In this case, the water stoppage and water reduction effect is high in large quantities of spring water, and since the strength when not foamed is high, the water stoppage and water reduction effect can be obtained even under conditions of high pressure spring water.

However, in the case of mountain tunnels, for example, there are often parts with spring water and parts without spring water in the cross section. Therefore, if there is a part where there is no spring water, the injection amount is determined assuming that the entire cross section is free of spring water. Therefore, as in Patent Document 2, the foaming ratio is The injection amount is determined by setting the value to 1, and the injection amount tends to increase. Moreover, the injection material having physical properties as disclosed in Patent Document 2 is expensive, and there is a problem in 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 and water-stopping and water-reducing properties and stabilization of the ground, and there is room for improvement in this respect.

The present invention has been made in view of the above-mentioned problems, and provides a water-reducing ground improvement material and a ground improvement material that can reduce the cost of materials while ensuring water stoppage and ground improvement effects. 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 that has a water-reducing effect and a ground improvement effect when filled into bedrock or ground, and is a urethane-based water stop material. The urethane-based water stop material has the physical property of foaming even when in contact with water or not in contact with water. The main component of 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, and the liquid B has a viscosity of 150 to 350 mPa·s at a temperature of 25°C. The specific gravity at 250 mPa・s and a temperature of 20°C is 1.20 to 1.26, and the expansion ratio when in contact with water and the expansion ratio when not in contact with water are 6 to 10 times, respectively. The strength is 15 to 25 MPa when expanded twice .

In addition, the stable strengthening method according to the present invention is a ground stabilization method in which the bedrock or ground is filled with a water-reducing ground improvement material that has a water-reducing effect and a ground improvement effect when filled into the bedrock or ground. The water-reducing ground improvement material is made of a urethane-based water-stopping material, and has a physical property of foaming even when in contact with water or not in contact with water, and the urethane-based water-stopping material The foam contains a liquid A consisting of a polyol catalyst and a liquid B consisting of a polyisocyanate as main components, and has a foaming ratio of 6 to 10 times when in contact with 1% water and when not in contact with water. The A liquid 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, and the B liquid has a viscosity of 150 to 250 mPa·s at a temperature of 25°C and a temperature of The water-reduced ground improvement material has a specific gravity of 1.20 to 1.26 at 20° C., has an injection pressure of 0.5 MPa or more, an initial injection pressure of 0.7 MPa or more , and has a compressive strength that is twice as high when expanded. It is characterized by being injected into bedrock or earth at a pressure of 15 to 25 MPa .

In the present invention, the water-reduced ground improvement material is a material that foams when it comes into contact with water, and also foams in places where it does not come into contact with water. Water reduction effects can also be obtained, such as improving workability during construction work and suppressing declines in groundwater levels. That is, when the water-reducing ground improvement material of the present invention is injected into poor ground, the water-reducing effect can be gradually enhanced while contacting with spring water and forming a foamed solid body. Therefore, by continuously injecting the water-reducing ground improvement material, it is possible to form a weakly foaming zone and reduce water to an extent that does not interfere with tunnel excavation work, etc.

In addition, even in places with complex geological conditions where spring water occurs partially, or even in places where there is no spring water, it is possible to provide a certain degree of foaming properties, so injection can be used. It is possible to ensure the permeability of the water-reducing ground improvement material to the ground, and as described above, it is possible to effectively exhibit the water-stopping and ground-improving effects at the same time. Therefore, even under conditions of large amounts of spring water or high-pressure spring water, the injected water-reducing ground improvement material foams, making it possible to stop or reduce water.
In this way, the water-reduced ground improvement material of the present invention foams even when it is not in contact with water, so the overall injection amount is lower than when injecting a material that does not foam when it does not come into contact with water. Therefore, it is possible to reduce the material cost.

Furthermore, in the present invention, by foaming, the consolidated strength of the water-reduced ground improvement material is suppressed to be lower than the consolidated strength of the non-foamed injection material. Therefore, high-pressure injection is not required, the load placed on the injection equipment used for injection can be reduced, and general-purpose equipment can be used. For example, equipment for ultra-high pressure is no longer required, and costs can be reduced.

Furthermore, in the present invention, the foaming ratio when in contact with water does not become excessively large compared to the foaming ratio when not in contact with water, and a decrease in improved strength during foaming can be suppressed.

Furthermore, in the case of mountain tunnels, the water-reducing ground improvement material of the present invention can be filled into bedrock or ground to improve the ground even if the water pressure is high water pressure of 0.5 MPa or more. Stabilization methods 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 materials while ensuring the water stoppage effect and the ground improvement effect.

1 is a partially broken vertical cross-sectional view showing the configuration of a test device according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, a water-reduced ground improvement material and a ground stabilization method according to an embodiment of the present invention will be described based on the drawings.

The water-reducing ground improvement material of this embodiment is a water-reducing ground improvement material that has a water-reducing effect and a ground improvement effect when filled into bedrock or ground. The water-reducing ground improvement material is made of a urethane-based water-stopping material, and has the physical property of foaming whether it comes in contact with water or not.

As the water-reducing ground improvement material, for example, a composition described in the patent document of JP-A No. 2015-117304 can be adopted. That is, as an example of a water-reduced ground improvement material, a substantially water-free injection drug composition is composed of component (A) containing a polyol and an amine compound, and component (B) containing an isocyanate compound. In this case, an injection drug composition can 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-reduced ground improvement material of this embodiment, the (A) component and the (B) component are mixed at an appropriate mixing ratio during use to form a cured product.

The water-reduced ground improvement material has a gel time of 30 to 90 seconds (60 ± 30 seconds) when components (A) and (B) are mixed at 20°C, regardless of whether or not there is water contact. It is preferably 45 to 75 seconds (60±15 seconds).

It is preferable that the foaming ratio of the water-reduced ground improvement material is at least 3 times or more in both cases of contact with water and cases of non-contact with water. Note that, in order to reduce the negative impact on the environment when the cured product flows out due to water leakage or spring water, the foaming ratio of the cured product is preferably low, for example, about 8 times. Here, in the present embodiment, the expansion ratio is a value calculated by dividing the volume of the cured product after the completion of the curing reaction by the volume of the raw materials (A) component and (B) component. . The expansion ratio in the case of contact with water is measured by adding 1 part by mass of water to 100 parts by mass of component (A), mixing component (B), and foaming the mixture.
In addition, it is more preferable that the foaming ratio of the water-reduced ground improvement material be approximately the same when in contact with water and when not in contact with water (8 times in each example 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 determined by mixing components (A) and (B) without adding water, pouring a predetermined amount into a φ50mm x 100mm mold, covering it, and restraining it. A test piece of φ50 mm x 100 mm was prepared by foaming and curing, and the test piece was measured using an Instron universal testing machine in accordance with JIS A1216.

Moreover, in this 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 mountain tunnels, even if the water pressure is covered by the earth at a high water pressure of 0.5 MPa or more, the water-reduced ground improvement material of this embodiment can be filled into the bedrock or ground to stabilize the ground. law can be applied.

In the water-reduced ground improvement material and ground stabilization method according to the present embodiment, for example, urethane-based injection forepoling is performed for the purpose of preventing the top of the face from collapsing and preventing the spread of loosening during tunnel excavation. In the construction method or the injection type long pre-concrete construction method (AGF construction method), it is used to stabilize and strengthen rock with fracture zones and unstable soft ground by consolidating it, and to stabilize and strengthen by filling voids between the ground and concrete segments. Strengthening, stabilizing and strengthening by sealing cavities in earth and sand, rocks, bricks, coal, etc., repairing cracks in concrete and other artificial structures, stabilizing and strengthening through reinforcement, and rock formations with leaks or springs. It is injected into bedrock or earth to solidify it to stop or reduce water.
There are no particular limitations on the method of injecting the water-reduced ground improvement material; for example, multiple holes are drilled at predetermined intervals in the bedrock or ground, hollow bolts are inserted into these holes, and the openings of the bolts are It is possible to employ a known method of injecting a ground improving material with reduced water content into bedrock or ground and solidifying it.

In this embodiment, the water-reduced ground improvement material is used to fill the bedrock or the ground, so that the water-reduced ground improvement material foams when it comes into contact with water, and also foams in places where it does not come into contact with water. A strong cured product is obtained, which exhibits the effect of improving the ground, while also providing a water-reducing effect, such as improving workability in mountain tunnel construction and suppressing a drop in the groundwater level. That is, when the water-reducing ground improvement material of this embodiment is injected into poor ground, the water-reducing effect can be gradually enhanced while contacting with spring water and forming a foamed solid body. Therefore, by continuously injecting the water-reducing ground improvement material, it is possible to form a weakly foaming zone and reduce water to an extent that does not interfere with tunnel excavation work, etc.

Furthermore, in this embodiment, it is possible to provide a certain degree of foaming properties even in places with complex geological conditions where spring water is partially generated, or even in places where there is no spring water. Since this is possible, it is possible to ensure the permeability of the water-reducing ground improvement material to be injected into the ground, and as described above, it is possible to effectively exhibit the water-stopping and ground-improving effects at the same time. Therefore, even under conditions of large amounts of spring water or high-pressure spring water, the injected water-reducing ground improvement material foams, making it possible to stop or reduce water.
In this way, the water-reduced ground improvement material of this embodiment foams even when it is not in contact with water, so the overall injection rate is lower than when injecting a material that does not foam when it does not come into contact with water. The amount can be reduced, and material costs can be reduced.

Furthermore, in this embodiment, by foaming, the consolidated strength of the water-reduced ground improvement material is suppressed to be lower than the consolidated strength of the non-foamed injection material. Therefore, high-pressure injection is not required, the load placed on the injection equipment used for injection can be reduced, and general-purpose equipment can be used. For example, equipment for ultra-high pressure is no longer required, and costs can be reduced.

In addition, in this embodiment, by foaming at a foaming ratio of 3 times or more even without contact with water, it is possible to more effectively achieve the soil improvement effect and the water stoppage and water reduction effect. .

Furthermore, in the water-reduced ground improvement material of this embodiment, the foaming ratio when in contact with water and the foaming ratio when not in contact with water are approximately the same, so that the foaming ratio when in contact with water is equal to that of water. On the other hand, the foaming ratio does not become excessively large compared to the non-contact foaming ratio, and it is possible to suppress a decrease in improved strength during foaming.

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

Next, examples conducted to prove the effects of the water-reducing ground improvement material and the ground stabilization method according to the embodiment described above will be described below.

(Example)
In this example, the urethane-based water-reducing ground improvement material of the embodiment described above was subjected to an injection test under the same test conditions as for spring water to confirm the water stopping effect and the ground improvement effect.
In the test, as shown in Figure 1, the injection material P (water-reduced ground improvement material) is injected into a tubular test device 1 simulating a tunnel, and the injection amount of the injection material P, water stop state, curing status, and curing are measured. This is to confirm the range.

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

In the test device 1, crushed stones 12 are packed into a PVC pipe 11, and water W made of tap water is injected into the crushed stones 12 from an inlet 11a at one end of the PVC pipe 11. The water W is discharged from the drain port 11b at the end of the drain port 11b, thereby reproducing the state of running water. Two PVC pipes 11 having an outer diameter of 76.3 mm and a length of 3 m were coaxially connected, and a total length of 6 m was adopted. A variable bypass valve 13 was attached to the inlet 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 (liquids A and B) of the injection material P is connected to the intermediate part in the length direction of the PVC pipe 11, and the injection is performed using a short pipe mixer (not shown). Material liquid is injected.
The discharge amount (injection amount) of the injection material P was 5 L/min, and the injection amount of water W was 10 L/min. Note that the injection material P and water W to be injected are cooled to about 20 to 25° C. and 15° C., respectively, by a cooling device (not shown).

Table 2 shows test patterns based on three cases (implementation cases 1 and 2, and comparison case). In this test, 10 L/min of water W is injected, and the water stopping effect is confirmed by stopping the flow of water from the drain port 11b of the PVC pipe 11.
First, a curing confirmation test was conducted to confirm the properties of the three types of injection materials P used in the test. Specifically, as shown in Table 3, it was confirmed that the curing time and expansion ratio of each injection material P were within the specifications.

The test results are shown in Table 4. In addition, regarding implementation case 2, since the water reduction effect was confirmed when the bypass opening pressure was 0.5 MPa, a test was also conducted with the bypass opening pressure set to 1.0 MPa.
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 remain in the crushed stones 12 of the PVC pipe 11 forming the simulated earth. In this test, the injection material P was in contact with running water immediately after being stirred, and it can be assumed that this was because a mixture with a relatively low viscosity flowed out before the silica resin started to harden.

On the other hand, the injection material P (3-8, 8-8) in Implementation Cases 1 and 2 flows downstream from the injection pipe 14 at the injection point together with running water at the initial stage of injection, but the stirred injection material P flows into the PVC pipe 11. It was confirmed that water was reduced by remaining in the crushed stone 12 and then starting to harden, and it was confirmed that there was a water reduction effect. In addition, when the bypass opening pressure is 0.5 MPa, for both the injection materials P (3-8, 8-8) in implementation cases 1 and 2, the injection is continued until the bypass valve 13 is opened, that is, until water is injected. There was no change in the injection amount of 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 could be reduced to about half of the comparison case, compared to 10 kg in the comparison case, 8 kg in implementation case 1, and 5 to 6 kg in implementation case 2.
In case 2 (8-8) where the bypass opening pressure is 1.0 MPa, a water reduction effect was also observed, and the amount of injection until the bypass valve 13 opened increased, but at the time when the water reduction was confirmed. The injection amount was equivalent to that when the bypass opening pressure was 0.5 MPa.

Although the embodiments of the water-reduced ground improvement material and the ground stabilization method according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and may be modified as appropriate without departing from the spirit thereof. Can be changed.
For example, in the example of this embodiment, the foaming ratio of the water-reduced ground improvement material is 3 times when there is no water contact, 8 times when there is water contact, and 8 times when there is no water contact. Although two examples are shown in which the foaming ratio is 8 times when there is water contact, the foaming ratio is not limited to this. In short, any water-reducing ground improvement material that is made of a urethane-based water-stop material and has physical properties that foams even when in contact with water or not in contact with water is sufficient. Furthermore, it is preferable that the foaming ratio when in contact with water and the foaming ratio when not in contact with water are each at least 3 times or more.

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

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

Claims (2)

A water-reducing ground improvement material that has a water-reducing effect and a ground improvement effect when filled into bedrock or ground,
It is made of urethane-based waterproof material, and has the physical property of foaming even when it comes in contact with water or not.
The urethane-based water stop material has a liquid A consisting of a polyol and a catalyst and a liquid B consisting of a polyisocyanate as main components,
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 B liquid 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 foaming ratio when in contact with water and the foaming ratio when not in contact with water are respectively 6 to 10 times,
A water-reduced ground improvement material characterized by a compressive strength of 15 to 25 MPa when expanded twice . A ground stabilization method in which the bedrock or ground is filled using a water-reducing ground improvement material that has a water-reducing effect and a ground improvement effect when filled into the bedrock or ground,
The water-reduced ground improvement material is
It is made of urethane-based waterproof material, and has the physical property of foaming whether it comes in contact with water or not.
The urethane-based water stop material has a liquid A consisting of a polyol catalyst and a liquid B consisting of a polyisocyanate as main components,
The foaming ratio is 6 to 10 times when in contact with 1% water and when not in contact with water,
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 B liquid 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 injected into the bedrock or the ground so that the injection pressure is 0.5 MPa or more, the initial injection pressure is 0.7 MPa or more , and the compressive strength is 15 to 25 MPa when expanded twice. A ground stabilization method that is characterized by:

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