JPH03451B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a soil mortar retaining wall construction method that effectively delays the time from soil mortar placement to core material erection. The soil mortar earth retaining wall construction method is a construction method in which soil mortar is created by adding soil materials such as excavated soil and water to a solidifying material such as cement material or bacillus material, and this is forced into a trench. While the installed soil mortar has not yet solidified, it is common practice to erect H-shaped steel as a core material to create earth retaining walls, and it has been successfully applied to temporary earth retaining walls for subway construction and other projects. Conventionally, in the soil mortar earth retaining wall construction method in which core material is erected, for example, in the case of a pouring depth of 20 m, the average time from the start of soil mortar pouring to the end of core material (steel material) erection is approximately 5. It takes time. As the depth increases, the time required to construct the steel material increases accordingly, and at a depth of about 50 m, it will take 10 hours. In the conventional construction method, if more than 5 hours have passed from the start of soil mortar pouring, the soil mortar will solidify, making it impossible to erect steel. The present invention aims to solve this problem. For this purpose, the present inventors investigated various formulations to retard the setting of soil mortar, and found that retarders normally used for concrete have little retarding effect on soil mortar, but they are generally used to prevent concrete from bleeding. It has been found that anti-breathing agents have a significant effect on retarding the setting of soil mortar. That is, the present invention provides a soil mortar retaining wall construction method in which a soil mortar is created by adding a solidifying agent and water to excavated soil, this is poured into an excavation trench, and a core material is built into the cast soil mortar. To provide a soil mortar earth retaining wall construction method, which is characterized in that setting of soil mortar is delayed by adding an appropriate amount of an anti-breathing agent, which is usually used to prevent concrete from breathing, to the mortar. As the anti-breathing agent, it is preferable to use water-soluble polymeric materials that are commonly used to prevent concrete from breathing, such as those containing methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, etc. as the main ingredient. In particular, commercially available anti-breathing agents include methylcellulose-based products under the trade name "Hi-Metrose" (manufactured by Shin-Etsu Chemical Co., Ltd.), "Metolose" (manufactured by Shin-Etsu Chemical Co., Ltd.), and "Marborose" (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.). “Himetrose” has been found to be particularly suitable. The optimal range for the amount of such anti-breathing agents to be blended varies depending on the type, but generally speaking, it is best to blend them in an amount of 0.2 to 1.2% by weight based on the solidifying agent of soil mortar. . The aforementioned “Hi-Metroise”
In the case of 0.4 to 1.2% by weight based on the solidified material,
Preferably, it is blended in an amount of 0.4 to 0.8% by weight. The present invention will be specifically explained below using representative test examples. As a soil mortar for testing, one consisting of the following solidifying agent and slurry was used in the following formulation. Solidifying material: blast furnace cement (slag content 30-60%), slurry: clayey soil from Saitama prefecture (silt content: 77%)
%, ur=56.3%, wp=32.1%, Ip=24.20, GS
= 2.53, W = 58%) Mixture; Solidifying agent = 200Kg or 250Kg per 1 m ³ of finished slurry = 1220 Kg per 1 m ² of finished kneading (W =
275%) When mixing this soil mortar,
A super retardant agent A or B agent and an anti-breathing agent C agent or D agent were added in an amount of 0.4% or 0.8%, respectively, based on the weight of the solidifying material. However, super retardant A; polyol complex (trade name Bozolith)
100XR) Agent B: Oxycarboxylic acid salt (trade name: Palic T) Anti-breathing agent Agent C: Methylcellulose (trade name: Hymetrose) Agent D: Polyvinyl alcohol. The soil mortar of each composition was subjected to a Proctor penetration test every hour after kneading, and the relationship between the rise time of the penetration resistance value and the addition rate of each additive was investigated. The results are shown in Figure 1. Here, the rise time of the penetration resistance value is the time corresponding to the point where the tangent before the rise intersects the connection after the rise, based on the relationship between the elapsed time and the actually measured penetration resistance value. From the results shown in Figure 1, agent A and agent B as super retardants
It can be seen that agent C and agent D as anti-breathing agents have a greater effect on delaying the rising time, that is, retarding the setting of soil mortar, than the anti-breathing agents. More specifically, with retarder A, the rise time increases linearly as the addition rate increases,
In addition, with retarder B, the rise time increases even with a small amount added, but the effect is saturated with a small amount, whereas with antibreathing agent C, the rise time increases dramatically with a small amount. In the case of anti-breathing agent D, when the amount exceeds a certain amount (approximately 0.4%), the rise time increases rapidly. Table 1 below calculates the possible time for erecting steel materials during construction using the soil mortar retaining wall construction method based on the rise time test results described above, and summarizes the results.

【table】

[Table] From the results in Table 1, it can be seen that the steel construction time is the longest when 0.8% C agent is added, and construction can be performed for up to about 12 hours after pouring. Considering this result in relation to the rise time in Figure 1, even when 0.8% C agent is added, the increase in the rise time is small (C agent curve in Figure 1), but the steel erection time is It can be taken for a long time, therefore, C
This indicates that soil mortar with additives increases its strength slowly after it rises, and it can be said that it is a suitable material for the earth retaining wall construction method that penetrates the core material. Next, the amount of solidifying material used was set constant at 270 kg, and C
Soil mortars were prepared in the same manner as described above, except that the additive rate was varied at four levels: 0, 0.2, 0.4, and 0.6%, and the unconfined compressive strength thereof was measured. The results are shown in Figure 2. From the results shown in Figure 2, the unconfined compressive strength is approximately 30 kgf/cm ² without additives, and with agent C
Approximately 25Kgf/cm ² with 0.2Kg addition, approximately 23Kg with 0.4Kg addition
f/cm ² , approximately 22Kgf/cm ² with addition of 0.6Kg, and as the addition rate increases, the unconfined compressive strength decreases exponentially, and when 0.4Kg or more is added, almost no decrease in strength is observed. It can be seen that the content is about 70% of that of additive-free. In this way, even if the addition amount of C agent is increased from about 0.4%, the strength decreases only slightly, and judging from the penetration resistance value mentioned above, it is found that addition of 0.4% by weight or more to the solidifying material is It can be said that it is desirable. Furthermore, according to the present invention, since a material that originally has a breathing prevention function is used, it is advantageous in that breathing can be reduced to 0%, and the fluidity of soil mortar is also improved by consistency tests. flow cone)
The requirement of 20 seconds or less can be met. As explained above, the present invention is based on the discovery that an agent used as an anti-breathing agent in ordinary concrete can be used in soil mortar to retard setting while suppressing a decrease in strength. The soil mortar earth retaining wall construction method has a very beneficial effect in increasing the depth and scale of the construction, as well as improving workability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the relationship between the addition rate of additives to soil mortar and rise time, and FIG. 2 is a diagram showing the relationship between the addition rate of anti-breathing agent and the uniaxial compressive strength of soil mortar.

Claims (1)

[Scope of Claims] 1. In a soil mortar retaining wall construction method in which a soil mortar is created by adding a solidification agent and water to excavated soil, this is poured into an excavation trench, and a core material is built into the cast soil mortar. , a delayed-type soil mortar material is used, which is characterized in that an anti-breathing agent made of a water-soluble polymer substance, which is usually used to prevent concrete from breathing, is blended into the soil mortar to delay the setting of the soil mortar. Earth retaining wall construction method. 2. The earth retaining wall construction method according to claim 1, wherein the water-soluble polymeric substance is methyl cellulose.