Method of injecting grouting material for tunnel auxiliary construction and grouting device for tunnel auxiliary construction

Abstract

To stably inject and harden an injecting material without variation even when the environmental temperature is low in winter when injecting the injecting material in a tunnel auxiliary construction method.SOLUTION: A first liquid 21 as a raw material for an injection material 20 is heated in a first tank 11 by a first heater 31. A second liquid 22 as a raw material for the injection material 20 is heated in a second tank 12 by a second heater 32. The heated first liquid 21 from the first tank 11 and the heated second liquid 22 from the second tank 12 are joined together at a confluence part 45 of an injection pipe 40 and mixed. The mixed injection material 20 is injected into the ground 2 around a tunnel to stabilize the ground 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and an injection device for injecting grout into the ground as an auxiliary construction method for stabilizing the surrounding ground during tunnel construction, and in particular to an injection method and an injection device suitable for winter or cold regions. [Background technology]

[0002] When constructing a mountain tunnel using the NATM (New Austrian Tunneling Method) method, auxiliary construction methods may be implemented to stabilize the natural ground depending on the situation (see, for example, Patent Document 1). For example, in Patent Document 1, a steel foreplumbing pipe is driven into the natural ground ahead of the tunnel face, and grout is injected into the natural ground through an injection hole provided in the steel foreplumbing pipe. Examples of grouting materials that are used include urethane-based grouting materials, silica resin-based grouting materials, and cement-based grouting materials. Urethane-based grouting materials and silica resin-based grouting materials are foaming grouting materials made by mixing two liquids. It is known that cement-based injection materials are made by mixing two mixed liquids with different formulations and injecting them. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-002240 Summary of the Invention [Problem to be solved by the invention]

[0004] Foaming injection materials such as urethane and silica resin types vary in foaming time and expansion ratio depending on the ambient temperature and, in turn, the liquid temperature. If the liquid temperature is low, the foaming (hardening) time is long and the expansion ratio is low. This not only lengthens the construction time, but also makes it difficult to achieve the desired expansion ratio. If the temperature is too low, cement-based injection materials will experience inconsistent hardening. In view of the above circumstances, the present invention aims to ensure construction quality by enabling the injection material to be injected stably and evenly and hardened even when the environmental temperature is low, mainly in winter or in cold regions, during the injection of injection material in tunnel auxiliary construction methods. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides a tunnel auxiliary construction method for stabilizing the ground around a tunnel with a grouting material obtained by mixing a first liquid and a second liquid, comprising: heating the first liquid in a first tank by a first heater; heating the second liquid in a second tank by a second heater; mixing the heated first liquid from the first tank with the heated second liquid from the second tank; and a step of injecting the mixed grout into the natural ground.

[0006] The device of the present invention is an injection device used in a tunnel auxiliary construction method that stabilizes the ground around a tunnel with an injection material formed by mixing a first liquid and a second liquid, a first tank for storing the first liquid; a second tank for storing the second liquid; a first heater provided in the first tank; a second heater provided in the second tank; an injection pipe including two individual injection pipe sections extending from the first tank and the second tank, respectively, and having their tip sections joined together, and a joint injection pipe section extending from the joint section of these individual injection pipe sections; The present invention is characterized by the following.

[0007] At least one of the first tank and the second tank is preferably provided with an agitator. [Effects of the Invention]

[0008] According to the present invention, when injecting grouting material in a tunnel auxiliary construction method, the first and second liquids can be heated to temperatures close to the appropriate levels, even when the ambient temperature is low, mainly in winter or in cold regions. Therefore, the grouting material can be injected and hardened stably without variation, ensuring construction quality. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the injection of grout using an injection device for a tunnel auxiliary construction method according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the injection of grouting material by the injection device for tunnel auxiliary construction method according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. <First embodiment (Fig. 1)> Figure 1 shows a NATM tunnel 1 under construction. The AGF (ALL Grand Fasten) method is being used as an auxiliary construction method to stabilize the ground around the tunnel, particularly the ground 2 ahead of the tunnel face. A steel foreplow pipe 3 has been driven into the ground 2 ahead of the tunnel face. A tunnel auxiliary construction injection device 10 is installed inside the tunnel 1. The tunnel auxiliary construction injection device 10 injects injection material 20 into the ground 2 ahead of the tunnel face through the steel foreplow pipe 3. A silica resin-based injection material, which is a foaming injection material, is used as the injection material 20. The silica resin-based injection material is a modified polyurethane made from special sodium silicate (liquid A) and modified polyisocyanate (liquid B). Hereinafter, the special sodium silicate liquid A will be referred to as "first liquid 21" and the modified polyisocyanate liquid B will be referred to as "second liquid 22" as appropriate.

[0011] The injection device 10 for the tunnel auxiliary construction method includes two tanks 11 and 12, a heating system 30, and an injection pipe 40. A first liquid supply source 13 is connected to the first tank 11. A first liquid 21 from the first liquid supply source 13 is supplied to and stored in the first tank 11. The first liquid 21 in the first tank 11 is stirred by a first stirrer 15 to prevent component separation and to keep the liquid temperature uniform.

[0012] A second liquid supply source 14 is connected to the second tank 12. A second liquid 22 is supplied from the second liquid supply source 14 to the second tank 12 and stored therein. The second liquid 22 in the second tank 12 can be stirred by a second stirrer 16. In addition, since the modified polyisocyanate of the second liquid 22 is unlikely to cause component separation, the second agitator 16 may be omitted from the viewpoint of component separation. On the other hand, from the viewpoint of making the liquid temperature of the second liquid 22 uniform, it is desirable to provide the second agitator 16.

[0013] The heating system 30 includes heaters 31 and 32, temperature sensors 33 and 34, and a controller 35. The first heater 31 and the first temperature sensor 33 are housed in the first tank 11 and are in contact with the first liquid 21. The first heater 31 is configured as a rod-shaped or linear electric heater extending vertically. A control signal line 31c of the first heater 31 and a detection signal line 33c of the first temperature sensor 33 are connected to the controller 35. The controller 35 controls the output of the first heater 31 based on the temperature detected by the first temperature sensor 33 so that the temperature of the first liquid 21 becomes equal to or approaches the first set temperature. The first set temperature is, for example, around 20°C (approximately 20°C ± 5°C).

[0014] The second heater 32 and the second temperature sensor 34 are housed in the second tank 12 and are in contact with the second liquid 22. The second heater 32 is configured as a rod-shaped or linear electric heater extending vertically. A control signal line 32c of the second heater 32 and a detection signal line 34c of the second temperature sensor 34 are connected to a controller 35. The controller 35 controls the output of the second heater 32 based on the temperature detected by the second temperature sensor 34 so that the temperature of the second liquid 22 becomes equal to or approaches the second set temperature. The second set temperature is, for example, around 20°C (approximately 20°C ± 5°C).

[0015] The injection pipe 40 includes two individual injection pipe sections 41, 42 and a confluent injection pipe section 46. The first individual injection pipe section 41 extends from the first tank 11. A first injection pump 43 is provided in the first individual injection pipe section 41. A second individual injection pipe section 42 extends from the second tank 12. A second injection pump 44 is provided in the second individual injection pipe section 42.

[0016] The tips of the individual injection pipe sections 41, 42 are joined together at a joining section 45. A joining injection pipe section 46 extends from the joining section 45. The joining injection pipe section 46 is connected to the proximal end of the front-receiving steel pipe 3. In other words, the front-receiving steel pipe 3 constitutes the pipe section of the joining injection pipe section 46 that is buried in the natural ground 2. Although not shown, a static mixer is provided inside the front-receiving steel pipe 3 to promote mixing of the first liquid 21 and the second liquid 22. Discharge holes 3d are formed in various places on the pipe wall of the front-receiving steel pipe 3.

[0017] The tunnel auxiliary construction method injection device 10 is suitable for use in winter or cold regions, and is operated as follows. <First heating step> The first liquid 21 (special sodium silicate) in the first tank 11 is heated by the first heater 31. This makes it possible to heat the first liquid 21, which is, for example, around 10°C, to a set temperature of around 20°C. Alternatively, even when the outside air temperature (°C) is in the single digits or below freezing, the first liquid 21 can be heated to 10°C or higher. By performing the first heating step before the mixing step described below, it is possible to ensure sufficient heating time for the first liquid 21 (special sodium silicate).

[0018] <Second heating process> The second liquid 22 (modified polyisocyanate) in the second tank 12 is heated by the second heater 32. This makes it possible to heat the second liquid 22, which is, for example, around 10°C, to a set temperature of around 20°C. Alternatively, even when the outside air temperature (°C) is in the single digits or below freezing, the second liquid 22 can be heated to 10°C or higher. By performing the second heating step before the mixing step described below, it is possible to ensure sufficient heating time for the second liquid 22 (modified polyisocyanate).

[0019] <First delivery process> By driving the first injection pump 43, the heated first liquid 21 in the first tank 11 is sent out to the first individual injection pipe section 41. The sent-out amount of first liquid 21 is supplied from the first liquid supply source 13 to the first tank 11. This keeps the amount of first liquid 21 stored in the first tank 11 constant.

[0020] <Second delivery process> By driving the second injection pump 44, the heated second liquid 22 in the second tank 12 is sent out to the second individual injection pipe section 42. The sent-out amount of second liquid 22 is supplied from the second liquid supply source 14 to the second tank 12. This keeps the amount of second liquid 22 stored in the second tank 12 constant.

[0021] <Mixing process> The heated first liquid 21 in the first individual injection pipe section 41 and the heated second liquid 22 in the second individual injection pipe section 42 are joined at the joining section 45. As a result, the special sodium silicate of the first liquid 21 and the modified polyisocyanate of the second liquid 22 are mixed, and a foaming reaction, i.e., a reaction to produce the silica resin-based injection material 20, is initiated.

[0022] <Injection process> The silica resin grouting material 20 passes through the confluence grouting pipe section 46 and the inside of the forepiling steel pipe 3 while foaming, and is injected into the natural ground 2 through the discharge hole 3d. Even in winter or cold regions where the outside temperature is low, the silica resin-based injection material 20 can be sufficiently foamed in a short time because the injection material raw materials, special sodium silicate (first liquid 21) and modified polyisocyanate (second liquid 22), are preheated before mixing. Preheating both the special sodium silicate (first liquid 21) and modified polyisocyanate (second liquid 22) ensures that the silica resin-based injection material 20 can be sufficiently foamed in a short time. This means that the foaming (curing) time can be shortened and the foaming ratio can be increased. For example, even when the outside temperature is around 10°C, the foaming time can be set to around 70 seconds (70 seconds ± 20 seconds). As a result, even when the outside air temperature is low, the injection material 20 can be injected stably without variation, and construction quality can be ensured.

[0023] Next, another embodiment of the present invention will be described. In the following embodiments, the same components as those already described will be denoted by the same reference numerals in the drawings and the description thereof will be omitted. <Second embodiment (Fig. 2)> As shown in Fig. 2, in the injection device 10B for a tunnel auxiliary construction method according to the second embodiment, a cement-based injection material 50 is used as the injection material. The cement-based injection material 50 contains cement 52a, a water-reducing admixture 52b, a hardening agent 51a, a setting adjuster 51b, and water w as its components. The hardening agent 51a and the setting adjuster 51b are mixed together with the water w to form a first liquid 51 (liquid A), which is stored in a first tank 61. The cement 52a and the water-reducing admixture 52b are mixed together with the water w to form a second liquid 52 (liquid B), which is stored in a second tank 62.

[0024] The first tank 61 includes an upper tank portion 61a and a lower tank portion 61b. The upper tank portion 61a is provided with a first heater 31, a first temperature sensor 33, and a first agitator 15. The first liquid 51 is introduced into the upper tank portion 61a and heated by the first heater 31 to a temperature close to a set temperature.

[0025] A hopper 61c is provided at the bottom of the upper tank portion 61a. The hopper 61c is inserted into the open upper surface of the lower tank portion 61b. A first individual injection pipe portion 41 extends from the lower tank portion 61b.

[0026] When the shutter 61d of the hopper 61c is opened, a part or all of the heated first liquid 51 in the upper tank portion 61a is transferred to the lower tank portion 61b. Furthermore, the first liquid 51 is sent from the lower tank portion 61b to the first individual injection pipe portion 41.

[0027] The second tank 62 includes an upper tank portion 62a and a lower tank portion 62b. The upper tank portion 62a is provided with a second heater 32, a second temperature sensor 34, and a second agitator 16. The second liquid 52 is introduced into the upper tank portion 62a and heated by the second heater 32 to a temperature close to the set temperature.

[0028] A hopper 62c is provided at the bottom of the upper tank portion 62a. The hopper 62c is inserted into the open upper surface of the lower tank portion 62b. A second individual injection pipe portion 42 extends from the lower tank portion 62b.

[0029] When the shutter 62d of the hopper 62c is opened, a part or all of the heated second liquid 52 in the upper tank portion 62a is transferred to the lower tank portion 62b. Furthermore, the second liquid 52 is sent from the lower tank portion 62b to the second individual injection pipe portion 42. As a result, the first liquid 51 and the second liquid 52 join and mix at the joining section 45 to form the cementitious injection material 50. The cementitious injection material 50 is injected from the joining injection pipe section 46 and then from the forepiling steel pipe 3 into the natural ground 2 and hardens. Since the first liquid 51 and the second liquid 52 are heated before they are joined together, the cement-based injection material 50 can be injected and hardened stably without variation even when the environmental temperature is low in winter or in cold regions, thereby improving the construction quality.

[0030] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, the foamable injection material is not limited to the silica resin-based injection material 20 (FIG. 1), but may be a urethane-based injection material. The tunnel auxiliary construction method is not limited to the AGF method (long-length fore-receiving steel pipe construction method), but may also be the head bolt method. [Industrial Applicability]

[0031] The present invention can be applied, for example, to auxiliary construction methods during NATM tunnel construction. [Explanation of symbols]

[0032] 1. NATM tunnel 2. Ground 3 Pre-supported steel pipe 10,10B Tunnel auxiliary construction method injection device 11 First Tank 12 Second Tank 20 Silica resin injection material 21 First liquid (special sodium silicate) 22 Second liquid (modified polyisocyanate) 30 Heating System 31 First heater 32 Second heater 33 First temperature sensor 34 Second temperature sensor 35 Controller 40 Injection tube 41 1st individual injection pipe section 42 2nd individual injection pipe section 43 First infusion pump 44 Second infusion pump 45 Junction 46 Merging injection pipe section 50 Cement-based injection material 51 1st liquid (A liquid) 52 2nd liquid (B liquid) 61 First Tank 62 Second Tank

Claims

1. A method for injecting a grouting material in a tunnel auxiliary construction method for stabilizing the ground around a tunnel with a grouting material obtained by mixing a first liquid and a second liquid, heating the first liquid in a first tank by a first heater; heating the second liquid in a second tank by a second heater; mixing the heated first liquid from the first tank with the heated second liquid from the second tank; and injecting the mixed grout into the natural ground.

2. An injection device used in a tunnel auxiliary construction method that stabilizes the ground around a tunnel with an injection material formed by mixing a first liquid and a second liquid, a first tank for storing the first liquid; a second tank for storing the second liquid; a first heater provided in the first tank; a second heater provided in the second tank; an injection pipe including two individual injection pipe sections extending from the first tank and the second tank, respectively, and having their tip sections joined together, and a joint injection pipe section extending from the joint section of these individual injection pipe sections; A tunnel auxiliary construction method injection device comprising:

3. 3. The injection device for a tunnel auxiliary construction method according to claim 2, wherein at least one of the first tank and the second tank is provided with an agitator.

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