Fluidization-treated soil

Abstract

To enhance uniaxial compression strength of fluidization-treated soil having a specific gravity of 1.15 to 1.43, and enhance a recycling rate.SOLUTION: Fluidization-treated soil is obtained by mixing adjusted muddy water containing water and solid particles, and a solidification material, and has a recycling rate of 97% or more. A specific gravity of the adjusted muddy water is 1.1 to 1.3, and a moisture content of the adjusted muddy water is 62-85%. The soil particles contain 50-65% of fine grain components with a grain diameter of less than 75 μm, and the solidification material contains blast furnace C kind cement in the uniaxial compression strength at a material age of 28 days of 200 kN / m2 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to liquefied treated soil. [Background technology]

[0002] The applicant of the present application has previously proposed techniques relating to liquefied treated soil as shown in Patent Documents 1 and 2.

[0003] Patent Document 1 discloses a method of filling surplus soil into spaces such as the inside of pipes by using construction surplus soil, in which the facility site where the surplus soil is stored and the work site where the space where the surplus soil is filled are different locations, and at least a storage tank is installed at the facility site, water is mixed with the surplus soil stored in the storage tank, and after mixing the surplus soil with water, the surplus soil is transported to the work site without mixing in cement at the facility site, and a vacuum truck equipped with a tank and a vacuum pump is used, and at least a mixer, vacuum truck, and sand pump are installed at the work site, the transported surplus soil is transferred to the mixer, cement is added, and the mixture is kneaded to form a slurry mortar with a flow of 300 mm to 450 mm, and the formed mortar is transferred to the tank of the vacuum truck, and a sand pump is connected to the tank of the vacuum truck, and a discharge hose is connected to the sand pump, and the sand pump and the vacuum pump of the vacuum truck are operated to pressure-feed the mortar into the space from outside. In this method of filling surplus soil, a relatively large amount of solidification material (1 m of the above adjusted sludge) is used for the adjusted sludge with a relatively high moisture content and specific gravity of 1.15. 3 By adding 150 kg of the solidification material to the concrete, the fluidity is extremely high, allowing it to be transported not only by agitator trucks (concrete mixer trucks) but also by vacuum trucks, and it is possible to pump it up to 500 m or more in underground pipes. While the method of Patent Document 1 was able to extend the pumping distance in underground pipes as described above, it was unable to achieve high uniaxial compressive strength. In particular, in open-air backfilling sites, it is desirable that the strength of the ground after backfilling be approximately equal to or greater than the ground strength around the backfilling site before excavation.

[0004] Patent Document 2 solves the problems of Patent Document 1, and firstly, in a method of producing liquefied treated soil having a bleeding rate of 3% or less by adding a solidification material selected from cement, cement-based solidification material, cement-lime composite solidification material, and lime to sludge, and backfilling with the produced liquefied treated soil, the sludge is subjected to an adjusted sludge production step and a kneading treatment step, the adjusted sludge production step is a step of adjusting the moisture content of the sludge to obtain adjusted sludge having a specific gravity of 1.18 or more and less than 1.28, and the kneading treatment step is a step of mixing 1 m of the adjusted sludge with 1 m of the adjusted sludge. 3 The solidification material is added to the adjusted sludge in an amount of 150 kg or more but less than 260 kg and mixed. The mixing and mixing process further includes a dehydrated cake adding process in which dehydrated cake is added to the adjusted sludge. In the dehydrated cake adding process, the solidification material is added to the adjusted sludge that has been obtained in advance, and the sludge is then dehydrated to produce a dehydrated cake, which is then added to the adjusted sludge. The specific gravity of the liquefied treated soil at the end of the mixing and mixing process is 1.25 or more, and these processes result in a 28-day unconfined compressive strength of 200 kN / m 2 The liquefied treated soil is produced as described above. Secondly, the liquefied treated soil is transported and filled into the backfill space by a pump, and the unconfined compressive strength of the soil at 28 days is 200 kN / m 2 It is proposed to achieve the above backfill conditions.

[0005] Traditionally, blast furnace cement (Type B) has been widely used as a cement-based solidification material in liquefied treated soil, especially in soil that can be pumped underground through pipes more than 500 m.

[0006] Patent Documents 3 and 4 disclose changing the amount of blast furnace slag mixed in blast furnace cement. However, the technology disclosed in these documents is for high-specification liquefied treated soil with a high specific gravity, and does not apply to liquefied treated soil that can be pumped long distances. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4098675 [Patent Document 2] Patent No. 5269235 [Patent Document 3] Patent No. 6124519 [Patent Document 4] Patent No. 6508526 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to increase the unconfined compressive strength of liquefied treated soil with a specific gravity of 1.15 to 1.43. The problem to be solved by the present invention is to increase the recycling rate of liquefied treated soil with a specific gravity of 1.15 to 1.43. [Means for solving the problem]

[0009] The present invention proposes changing the solidification material used for liquefied treated soil with a specific gravity of 1.15 to 1.43 from blast furnace type B cement to blast furnace type C cement. Blast furnace type B cement is cement that contains more than 30% but not more than 60% blast furnace slag (waste material), and blast furnace type C cement is cement that contains more than 60% but not more than 70% blast furnace slag (waste material).

[0010] (1) Comparison of unconfined compressive strength A comparison of the unconfined compressive strength of fluidized soils blended with blast furnace type B cement and blast furnace type C cement is shown below. Note that the following example is merely one specific example, and the present invention should not be understood as being limited to this specific example.

[0011] [Table 1]

[0012] As shown in the above example, when comparing the same blending amounts of blast furnace type B cement and blast furnace type C cement, the liquefied treated soil blended with blast furnace type C cement has a higher unconfined compressive strength. In other words, the unconfined compressive strength when blended with 80 kg of blast furnace type C cement is approximately the same as the unconfined compressive strength when blended with 150 kg of blast furnace type B cement.

[0013] (2) Comparison of recycling rates A comparison of the recycling rates (waste utilization rates) of fluidized treated soils blended with blast furnace type B cement and blast furnace type C cement is as follows: Note that the following example is merely one specific example, and the present invention should not be understood as being limited to this specific example.

[0014] (2-1) Recycling rate of blast furnace cement type B when blended with 150 kg Blast furnace type B cement 150 kg (49.34 L) + adjusted muddy water 1,200 kg (1,000 L) = liquefied treated soil 1,350 kg (1,049.34 L), specific gravity: Recycling rate of liquefied treated soil of 1.287 Here, the adjusted muddy water is obtained from construction waste soil or construction sludge, and the entire amount is assumed to be recycled.

[0015] The recycling rate r1 when not considering the recycling rate of blast furnace slag in blast furnace cement is: The formula for r1 is r1=(b / a+b)×100, which is 88.9%. however a: Mass of blast furnace cement type B b: Mass of adjusted muddy water a+b: Mass of liquefied soil

[0016] The recycling rate r2 when considering the recycling rate of blast furnace slag is: The formula for this is r2 = [(b+c) / (a+b)] × 100, which is 92.2%. however a: Mass of blast furnace cement type B b: Mass of adjusted muddy water a+b: Mass of liquefied soil a: Mass of blast furnace cement type B c: Mass of blast furnace slag in blast furnace type B cement The amount of blast furnace slag in the blast furnace type B cement is 30% by mass, and the entire amount is recycled.

[0017] (2-2) Recycling rate of blast furnace type C cement at 80 kg blend To obtain the same uniaxial compressive strength as when mixing 150 kg of blast furnace type B cement, it is sufficient to mix 80 kg of blast furnace type C cement. Blast furnace Cement 80 kg (27.03 L) + Adjusted mud water 1,200 kg (1,000 L) = Fluidized soil 1,280 kg (1,023.03 L), specific gravity: 1.251 Here, the adjusted muddy water is obtained from construction waste soil, and the entire amount is recycled.

[0018] The recycling rate r1 when not considering the recycling rate of blast furnace slag in blast furnace cement is: The formula is r1=(b / a+b)×100, which is 93.8%. however a: Mass of blast furnace cement type B b: Mass of adjusted muddy water a+b: Mass of liquefied soil

[0019] The recycling rate r2 when considering the recycling rate of blast furnace slag is: The formula is r2=[(b+c) / (a+b)]×100, which is 97.5%. however a: Mass of blast furnace cement type B b: Mass of adjusted muddy water a+b: Mass of liquefied soil a: Mass of blast furnace cement type C c: Mass of blast furnace slag in blast furnace type C cement The amount of blast furnace slag in the blast furnace type C cement is 60 mass %, and the entire amount is recycled.

[0020] As mentioned above, when compared based on the conventional general required strength, the recycle rate of fluidized soil containing blast furnace type C cement is higher than that of fluidized soil containing blast furnace type B cement.

[0021] As a result of the above, by changing the cement used in the liquefied treated soil to blast furnace type C cement, we have been able to provide "high-strength liquefied treated soil" and "highly recyclable liquefied treated soil." [Effects of the Invention]

[0022] The present invention has made it possible to increase the unconfined compressive strength of liquefied treated soil with a specific gravity of 1.15 to 1.43. The problem to be solved by the present invention is to increase the recycling rate of liquefied treated soil with a specific gravity of 1.15 to 1.43. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described. The liquefied treated soil according to the embodiment of the present invention is a mixture of adjusted muddy water and a solidification material.

[0024] It can be used as a backfill for underground spaces. In particular, it is desirable that the specific gravity be 1.15 to 1.43, so that it can be pumped over long distances. By changing the cement used as the solidification agent in this liquefied treated soil to blast furnace type C cement, it can be made into "high-strength liquefied treated soil" and "high-recycling liquefied treated soil."

[0025] (adjusted mud water) The specific gravity of the adjusted muddy water is 1.1 to 1.3, and particularly 1.12 to 1.30. The water content of the adjusted mud is 62 to 85%, and preferably 65 to 75%.

[0026] (soil particles) It is preferable that the content of fine particles having a particle size of less than 75 μm is 50 to 65% in order to obtain suitable fluidity. The fine fraction (<0.075mm) includes clay (<0.005mm) and silt (0.005 to <0.075mm), while the larger coarse fraction (0.075-75mm) includes sand (0.075-2mm) and gravel (2-75mm), although it is preferred that the soil particles of the present invention do not contain gravel.

[0027] (water) The water content of this adjusted mud is 62 to 85%, and it is particularly suitable to set it to 65 to 75%.

[0028] (Solidification material) The solidifying agent used is blast furnace type C cement. Blast furnace cement is made by mixing a specified amount of ground granulated blast furnace slag with Portland cement, and is classified into three types depending on the amount of ground granulated blast furnace slag: Type A (more than 5% but not more than 30%), Type B (more than 30% but not more than 60%), and Type C (more than 60% but not more than 70%), with Type B being the most widely used.

[0029] Blast furnace slag is a recycled product made by melting and separating non-iron components contained in iron ore in a blast furnace together with the ash from auxiliary raw materials such as limestone and coke, and the more blast furnace slag used, the higher the cement recycling rate and the higher the uniaxial compressive strength.

[0030] (adjusted mud and solidifying agent) The liquefied treated soil is produced by adding the above-mentioned solidifying material to the above-mentioned adjusted muddy water in a conventional manner and mixing them uniformly. The present invention has an unconfined compressive strength of 200 kN / m at 28 days. 2 The present invention provides a liquefied treated soil containing blast furnace type C cement in an amount of the above. Furthermore, the present invention uses a total volume of 1,000 liters / m of liquefied treated soil. 3 In contrast, the dry solidification material is 27 to 85 liters / m 3 The mixed liquefied treated soil was provided.

[0031] (Recycling rate of liquefied soil) The liquefied treated soil of the present invention has a recycle rate of 97% or more. Note that the recycle rate in the present invention refers to the mass ratio of recycled materials to the blended raw materials of the liquefied treated soil. In the case of 1,280 kg (1,023.03 L) of fluidized soil containing 1,200 kg (1,000 L) of adjusted mud water and 80 kg (27.03 L) of blast furnace type C cement, the entire amount of adjusted mud water is recycled, and the blast furnace slag of the blast furnace type C cement is recycled. Therefore, the recycling rate of liquefied treated soil is (Total mass of adjusted mud water + total mass of blast furnace slag) / Total mass of liquefied soil It can be calculated as follows. If the blending ratio of blast furnace slag in 80 kg of blast furnace type C cement is 60%, the recycling rate is: [(1200+80×0.6) / 1280]×100=97.5%. [Example]

[0032] Examples of the present invention will be shown below together with comparative examples, but the present invention should not be understood as being limited to these examples. Adjusted muddy waters 1 to 5 were prepared as shown in Table 2.

[0033] [Table 2]

[0034] Fluidized soil was prepared by adding a solidification agent (EMC: blast furnace type C cement, with a blending amount of blast furnace slag exceeding 60%) to 1,000 L (1,200 kg) of adjusted mud water 1 to 5 in the solidification agent blending amounts shown in Examples 1 to 5. For example, in Example 1, 70 kg of solidification agent was blended with adjusted mud waters 1 to 5, and there were five types of adjusted mud waters blended, numbered 1 to 5. Therefore, there are five types of adjusted mud waters in Example 1, corresponding to the type of adjusted mud water. A total of 25 types of adjusted mud waters 1 to 5 were prepared for Examples 1 to 5, and the unconfined compressive strength of each was measured at 28 days. The results are shown in Table 3.

[0035] [Table 3]

[0036] Similarly, for the comparative examples, a total of 25 types of liquefied treated soil were created by adding a solidification agent (BB: blast furnace type B cement, blast furnace slag content over 30%) to the adjusted mud waters 1 to 5 in the solidification agent content amounts of comparative examples 1 to 5.The unconfined compressive strength of each type was measured at 28 days old, and the results are shown in Table 4.

[0037] [Table 4] From the above, it was confirmed that in all of the examples, the unconfined compressive strength of the liquefied treated soil was increased compared to the comparison example.

[0038] Furthermore, when comparing samples with the same uniaxial compressive strength, the example required a smaller amount of solidification material than the comparative example, and the blending rate of blast furnace slag in the cement was higher, which increased the recycling rate of the liquefied soil.

Claims

1. In liquefied soil, which is a mixture of adjusted muddy water containing water and soil particles and a solidification material, The specific gravity of the adjusted mud water is 1.1 to 1.3, The water content of the adjusted mud water is 62 to 85%; The soil particles contain 50 to 65% fine particles with a particle size of less than 75 μm, The solidification material has an unconfined compressive strength of 200 kN / m at 28 days. 2 The blast furnace cement contains the above amount of C type cement, Fluidized treated soil characterized by a recycling rate of 97% or more.

2. In liquefied soil, which is a mixture of adjusted muddy water containing water and soil particles and a solidification material, The specific gravity of the adjusted mud water is 1.1 to 1.3, The water content of the adjusted mud water is 62% or more, The soil particles contain 50 to 65% fine particles with a particle size of less than 75 μm, The solidification material contains 60 to 70% by weight of blast furnace slag and 30 to 40% by weight of cement, The total amount of the liquefied soil is 1,000 liters / m 3 In contrast, the solidification material is 27 to 85 liters / m in a dry state. 3 It is a blended With that said, Fluidized treated soil characterized by a recycling rate of 97% or more.

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