Filling material

Abstract

This method prevents leakage through gaps while maintaining density without significantly changing the water-to-powder ratio. [Solution] The filler 1 contains water, a binder, and a thickener. The thickener is a nonionic water-soluble cellulose ether. The amount of water-soluble cellulose ether added is 2 to 7 kg / m 3 The binder consists of blast furnace slag fine powder, gypsum, and an expansive agent. Bentonite is included as an admixture. The water-binder ratio is 80-120%. Test results show that by adding a predetermined amount of water-soluble cellulose ether, the non-leakage properties can be improved while maintaining density without significantly changing the water-to-powder ratio.

Description

[Technical Field]

[0001] The present invention relates to a filling material injected into the cavity between the back of the tunnel lining and the surrounding ground, which prevents leakage from gaps such as joints and cracks in the lining. [Background technology]

[0002] Traditionally, if a cavity remains between the back of the tunnel lining and the surrounding ground, passive earth pressure does not occur in this cavity. This results in uneven pressure from the ground on the lining, which can cause cracking and failure of the lining concrete, as well as weathering of the ground and subsequent collapse, potentially leading to water leakage. For these reasons, backfill grouting work is performed to fill these cavities with filler material.

[0003] Typically, economical air mortar is used as the filler material injected into the cavity. For example, Patent Document 1 below discloses a cement composition comprising cement, a foaming agent, and water, wherein the content of the foaming agent relative to the total amount of the composition is greater than or equal to a predetermined amount. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-59070 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, due to its high fluidity, this type of air mortar is difficult to inject precisely into cavities and has a tendency to escape into cracks in the ground or joints and cracks in the lining. In addition, it is easily diluted with water, and in areas with groundwater, the water can cause defoaming, leading to material separation due to the leaching of mortar components, which can prevent adequate cavity filling.

[0006] One possible solution to this problem is to reduce the proportion of water in the filler and increase the proportion of powder. However, a high proportion of powder presents the following problem: (1) If the proportion of powder is large, the density of the filler increases, and if it is used to fill the void between the back of the lining and the ground, the load on the lining concrete increases, which can cause cracking. (2) If the proportion of powder is large, it is difficult to ensure proper fluidity, which may result in the powder not spreading throughout the entire cavity and leaving voids.

[0007] Therefore, the main objective of the present invention is to provide a filler that prevents leakage from gaps while maintaining density without significantly changing the ratio of water to powder. [Means for solving the problem]

[0008] To solve the aforementioned problems, the present invention according to claim 1 is a filler comprising water, a binder, and a thickener, The aforementioned thickener is a nonionic water-soluble cellulose ether, The amount of water-soluble cellulose ether added is 2-7 kg / m². 3 A filler is provided that is characterized by the following.

[0009] In the invention described in claim 1 above, for the purpose of controlling the non-leakage of the filler, a thickening agent consisting of a nonionic water-soluble cellulose ether is used at a rate of 2 to 7 kg / m³. 3 By adding this substance, it prevents the filler from leaking out through gaps in the lining. As is clear from the test results described later, by adding a predetermined amount of a thickener consisting of nonionic water-soluble cellulose ether, it becomes possible to improve leak resistance while maintaining density without significantly changing the water-to-powder ratio.

[0010] As part of the present invention according to claim 2, the filler according to claim 1 is provided, wherein the binder consists of blast furnace slag fine powder, gypsum, and an expansive agent.

[0011] In the invention described in claim 2 above, since fine powder of blast furnace slag is used as the main binder and cement is not used, the amount of carbon dioxide emissions during the manufacturing process can be significantly reduced, contributing to the realization of a decarbonized society.

[0012] As the invention according to claim 3, there is provided a filler according to claim 1 which contains bentonite as a admixture.

[0013] In the invention described in claim 3 above, by containing bentonite as an admixture, appropriate viscosity is generated, so that the non-leakage property from the gap can be enhanced.

[0014] As the invention according to claim 4, there is provided a filler according to claim 1 in which the water-binder ratio is 80 to 120%.

[0015] In the invention described in claim 4 above, while maintaining the ratio of water to the binder within the range usually used as a filler, leakage from the gap is prevented.

Effects of the Invention

[0016] As described in detail above, according to the present invention, leakage from the gap can be prevented while maintaining the density without significantly changing the ratio of water to powder.

Brief Description of the Drawings

[0017] [Figure 1] It is a cross-sectional view of a tunnel showing the cavity between the back of the lining and the natural ground. [Figure 2] Showing a test device, (A) is a front view and (B) is a bottom view. [Figure 3] It is a graph showing the relationship between the addition amount of water-soluble cellulose ether and the depth of the filler that has entered the 5 mm gap. [Figure 4] It is a graph showing the relationship between the addition amount of water-soluble cellulose ether and the 0-slump flow. [Figure 5] It is a graph showing the relationship between the addition amount of water-soluble cellulose ether and the 15-slump flow. [Modes for carrying out the invention]

[0018] Embodiments of the present invention will be described in detail below with reference to the drawings.

[0019] The filling material 1 according to the present invention is, for example, a backfill grout material injected into a cavity 4 formed between the back of the tunnel lining 3 and the surrounding ground, as shown in Figure 1. Other examples of applications for the filling material 1 include cavities formed between the sheet piles of the tunnel and the surrounding ground, and underground cavities beneath the road surface. However, in this document, we will primarily explain the case of injection into the cavity 4 between the back of the tunnel lining 3 and the surrounding ground, as shown in Figure 1.

[0020] The filler 1 comprises water, a binder, and a thickener, wherein the thickener is composed of a nonionic water-soluble cellulose ether. In particular, the filler 1 according to the present invention contains 2 to 7 kg / m of this water-soluble cellulose ether. 3 A distinctive feature is that it is characterized by this.

[0021] As is clear from the test results described later, the amount of water-soluble cellulose ether added was 2 kg / m³. 3 If the amount is smaller, the depth of the filler material that penetrates a 5 mm gap in the non-leakage test will not meet the standard value (350 mm or less). On the other hand, if the amount of water-soluble cellulose ether added is 7 kg / m³ 3 If it exceeds this amount, the lower limit of the standard value for 15 strokes of flow (130 mm or more) in the flow rate test will not be satisfied. For this reason, in this invention, the amount of water-soluble cellulose ether added is 2 to 7 kg / m 3 The method involves adding water-soluble cellulose ether within the specified range. This ensures that the non-leakage, 0-count flow, and 15-count flow values ​​in a 5mm gap are met, and a filler with excellent non-leakage properties and appropriate fluidity is obtained while maintaining density without significantly changing the water-to-powder ratio.

[0022] The aforementioned nonionic water-soluble cellulose ethers are known as cellulose-based admixtures and include HEC (hydroxyethylcellulose), HEMC (hydroxyethylmethylcellulose), and HPMC (hydroxypropylmethylcellulose), which have OH groups and are highly hydrophilic. Any one or two or more of these can be used. These water-soluble cellulose ethers have a high dissolution rate in nutrient solutions with a high pH, ​​such as concrete, and do not undergo chemical changes such as reaction, gelation, or decomposition in concrete.

[0023] The binder should primarily consist of blast furnace slag powder, to which gypsum and an expansive agent should be added. Because blast furnace slag powder is used as the binder and cement is not used, carbon dioxide emissions during the manufacturing process can be significantly reduced, contributing to the realization of a decarbonized society. The amount of blast furnace slag powder used should be, for example, 495 to 774 kg / m³. 3 It can be done this way.

[0024] As the blast furnace slag fine powder mentioned above, blast furnace slag fine powder for concrete as specified in JIS A 6206 can be used. JIS specifies three types according to the fineness of the powder: 4000, 6000, and 8000. Any of these may be used, but it is preferable to use the 4000 fineness powder, which has excellent fluidity immediately after mixing.

[0025] The blast furnace slag fine powder may consist solely of blast furnace slag fine powder, or it may have gypsum pre-added to it. There are no particular limitations on the type of gypsum added to the blast furnace slag fine powder, but anhydrous gypsum or hemihydrate gypsum can be used.

[0026] The gypsum used as a binder may be natural gypsum, by-product gypsum, or recycled gypsum, but by-product gypsum is preferred to contribute to the realization of a decarbonized society. Furthermore, gypsum is classified into dihydrate gypsum, hemihydrate gypsum, and anhydrous gypsum depending on the form of water present in its crystals, and any of these may be used, but hemihydrate gypsum is preferred because it has excellent moldability and good flow-filling properties when poured. The amount of gypsum to be added is, for example, 29 to 92 kg / m³.3 can be set as such.

[0027] As the expansion material, those defined in JIS A 6202 "Expansion Material for Concrete" can be used without limitation. The blending amount of the expansion material can be, for example, 20 to 50 kg / m 3 can be set as such.

[0028] Bentonite can be added to the filling material 1 as an admixture. By adding the bentonite, appropriate viscosity is generated in the filling material 1, so that the non-leakage property from the gap can be enhanced. The blending amount of bentonite can be, for example, 21 to 57 kg / m 3 can be set as such.

[0029] As the water, for example, seawater, brackish water, tap water, groundwater, rainwater, etc. may be used as they are, or a mixture of two or more of these may be used. The water-binder ratio (W / B), which is the ratio of the water (W) to the binder (B), can be within the range normally used as a filling material, and particularly 80 to 120% is preferable.

[0030] The method for manufacturing the filling material according to the present invention may be carried out by a conventionally known method. That is, in a concrete mixer or a mortar mixer, water and other constituent materials may be kneaded while being mixed, or after kneading a binder composed of water, blast furnace slag fine powder, gypsum, and an expansion material, a thickening agent or an admixture may be added and kneaded again, or after kneading water and blast furnace slag fine powder, gypsum and an expansion material may be added and kneaded again, and then a thickening agent or an admixture may be further added and kneaded again. Also, a part or all of the other constituent materials excluding water and liquid agents may be premixed before water injection.

[0031] As shown in FIG. 1, for the backfilling work, an injection pipe 5 communicating from the inner space of the tunnel 2 to the cavity 4 is installed in the covering work 3 in advance, and the filling material 1 is injected into the cavity 4 through this injection pipe 5. The injection effect is confirmed by the outflow situation from other injection holes, the injection pressure, the injection amount, etc.

Example

[0032] As shown in Table 1, various filling materials with altered compositions were subjected to fluidity tests and leak-proof tests. The test methods and specifications for the fluidity tests and leak-proof tests were determined based on the quality standards for backfill grout materials described in "Design and Construction Guidelines for Backfill Grouting in Sheet Pile Tunnels" by East Nippon Expressway Co., Ltd. et al. (October 2006).

[0033] The aforementioned fluidity test includes a test to measure the flow value while stationary and a test to measure the flow value while impacted. The test to measure the flow value while stationary is performed based on the cylinder method of JHS 313 "Consistency Test Method," and the flow value measured immediately after removing the hardened plastic cylinder vertically is measured as the 0-impact flow (stationary flow value). The standard value for this 0-impact flow is 80 to 155 mm. On the other hand, the test to measure the flow value while impacted is performed using a hardened plastic cylinder applied in the cylinder method of JHS 313 "Consistency Test Method" instead of the flow cone of JIS R 5201 "Flow Test," and the flow value measured after 15 drops over 15 seconds is measured as the 15-impact flow. The standard value for this 15-impact flow is 130 to 205 mm.

[0034] The aforementioned non-leakage test was conducted in accordance with the "Design and Construction Guidelines for Backfill Cavity Injection Work in Sheet Pile Tunnels" (October 2006) by East Nippon Expressway Co., Ltd. and others. The test apparatus was constructed as shown in Figure 2, by a) processing a wooden frame, wooden boards, and transparent acrylic plates to create a predetermined container, b) installing a transparent acrylic plate on the front side of the container so that the leakage into the gap (depth of injection material penetration) can be confirmed, c) creating a chute-like inlet of approximately 400 mm in length on one side of the container, and d) creating gaps of 1, 3, 5, 7, and 10 mm in the lower part of the container using expanded polystyrene. The test method was as follows: a) Injection material was poured into the test apparatus. However, the injection material was not poured directly, but rather poured in with one buffer in the chute on one side of the container. b) The discharge rate of the injection material was set to 30 liters / min. c) Injection was stopped when the material reached a height of 300 mm from the top of the expanded polystyrene. d) Measure the depth of the filler material that has entered each gap at 10 min, 30 min, and 60 min. The standard value at this time is that after 60 minutes, gaps of 5 mm or less are completely filled and densely packed (the depth of the filler material that has entered the gap is 350 mm or less).

[0035] The filler formulation and test results are shown in Table 1. The symbols used in the "Formulation" column of the table are as follows: W: Tap water Be: Bentonite BFS: Blast furnace slag fine powder Gy: By-product gypsum Ex: Expanding agent V: Nonionic water-soluble cellulose ether

[0036] [Table 1]

[0037] Regarding the non-leakage test in Table 1, Figure 3 shows a graph illustrating the relationship between the amount of water-soluble cellulose ether (V) added and the leakage depth into a 5 mm gap. Furthermore, regarding the flowability test in Table 1, Figure 4 shows a graph illustrating the relationship between the amount of water-soluble cellulose ether (V) added and the 0-count flow, while Figure 5 shows a graph illustrating the relationship between the amount of water-soluble cellulose ether (V) added and the 15-count flow.

[0038] As shown in Figure 3, in the non-leakage test, the amount of water-soluble cellulose ether (V) added was 1 kg / m³. 3 In this case, the leakage depth into the 5mm gap 60 minutes after injection exceeded 350mm, failing to meet the standard value of 350mm or less. On the other hand, when the amount of water-soluble cellulose ether (V) added was 2kg / m³ 3 In the above test, the leakage depth into the 5mm gap 60 minutes after injection was 350mm or less, satisfying the standard value.

[0039] Furthermore, as shown in Figure 5, the 15-dot flow rate in the flowability test was achieved when the amount of water-soluble cellulose ether (V) added was 8 kg / m³. 3 At that time, the measurement was 125 mm, which was outside the standard range of 130-205 mm and did not meet the standard value. On the other hand, the amount of water-soluble cellulose ether added was 7 kg / m 3 In the following cases, the 15-powder flow rate was within the range of 130-205 mm, satisfying the standard value. Note that for the 0-powder flow rate, as shown in Figure 4, the amount of water-soluble cellulose ether (V) added was 1-8 kg / m³. 3 In all aspects, the specifications of 80-155mm were met.

[0040] Based on the above results, in a filler containing water, a binder, and a thickener, a nonionic water-soluble cellulose ether is used as the thickener, and the amount of water-soluble cellulose ether added is 2 to 7 kg / m². 3By doing so, the standard value of 350 mm or less for the leakage depth into a 5 mm gap 60 minutes after injection in the non-leakage test is satisfied, and the standard values ​​for 0-pour flow and 15-pour flow in the fluidity test are also satisfied. This results in a filler that has appropriate fluidity and non-leakage from gaps while maintaining density without significantly changing the ratio of water to powder. The water-soluble cellulose ether is usually used to improve the resistance of concrete to segregation in water, but in this invention it is used to control the non-leakage of the filler. [Explanation of Symbols]

[0041] 1...filling material, 2...tunnel, 3...lining, 4...cavity, 5...injection pipe

Claims

1. A filler containing water, a binder, and a thickener, The aforementioned thickener is a nonionic water-soluble cellulose ether, The amount of water-soluble cellulose ether added is 2 to 7 kg / m³. ３ A filler characterized by the following:

2. The filler according to claim 1, wherein the binder comprises blast furnace slag fine powder, gypsum, and an expansive agent.

3. The filler according to claim 1, which contains bentonite as an admixture.

4. The filler according to claim 1, wherein the water-binding ratio is 80 to 120%.

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