JPH0790272A - Super-plasticizable back-filling material and back-filling process - Google Patents

Abstract

PURPOSE:To utilize the excavated soil as a back-filler for laying the pipes underground so as to maintain sufficient strength not only in the long material age but also in the short material age. CONSTITUTION:The excavated soil is mixed with a relatively large amount of water with stirring and the mud slurry is stirred together with a certain amount of a fly ash cement B and aluminate clinker mixture as a setting agent to increase the initial strength of the back-filling material as shown in A in the figure on the change in strength. The fly ash cement B and the aluminate clinker are mixed at a ratio of (0.8-1.3):1 whereby the strength in the long material age is markedly increased, too.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluidized backfilling material used for backfilling after a petroleum pipe, a gas pipe, a water pipe, a sewer pipe, etc. are piped in an excavation trench and a backfilling method. .

[0002]

2. Description of the Related Art When burying oil pipes and gas pipes in the ground, it is necessary to bury them at a certain depth or more from the surface of the earth in order to protect the oil pipes. In this burial work,
Excavated sediment without using any excavated sediment is transported to inland receiving land or sea landfill, backfilled with mountain sand, or placed in the vicinity of excavated trench to use excavated sediment. They are transported to a temporary storage site and stored, and after piping, a solidifying material is added to the excavated soil to backfill it.

[0003]

However, when backfilling only with mountain sand without using the excavated earth and sand, the excavated earth and sand is transported to a distant inland receiving site or a coastal landfill site. The regulations will reduce the number of sites for excavated sediment in the future. In addition, there is a problem that the quality mountain sand used for backfilling is insufficient.

Further, in the case of backfilling, the improved soil prepared by adding a solidifying material to mountain sand or excavated soil is spread out in several layers and compacted with a rammer or tamper. It takes a lot of time to be polite. Further, in the actual pipe burying work, it is difficult to completely compact all the wedge portions of the pipe installed in the long excavated groove, and there is a risk of insufficient compaction. Insufficient rolling of the wedge portion may cause depression or road subsidence in the buried portion, and if the buried pipe is a humor pipe or a ceramic pipe, the joint may come off and damage may occur. May occur.

Further, vibration and noise are generated when tampering with a rammer, tamper or the like, which causes problems such as noise pollution in urban areas.

In order to solve such disadvantages, a backfill material in which excavated soil is mixed with several percent to 10% of a commercially available cement-based solidifying material, and some water is added to have fluidity to some extent. For example, there is a method of pouring water into an excavation trench or a method of adding water while backfilling a backfilled portion with treated soil in which excavated soil and a solidifying material are mixed, fluidizing by applying vibration to fill the backfilled portion, and the like. It is disclosed in Japanese Patent Laid-Open No. 1-312118 and Japanese Patent Laid-Open No. 3-287909.

However, according to the method disclosed in Japanese Laid-Open Patent Publication No. 1-312118, for example, when the type of ground is volcanic ash cohesive soil, the strength is about 2.7 kgf / cm ² at 28-day age. Although the improvement of the long-term strength is shown as a problem, the initial strength such as 30-minute age is not shown, and the improvement of the initial strength has not been examined.

The present invention has been made in order to improve the above point, and it is possible to easily fill the lower part of the buried pipe, and to have a flow strength which is sufficient not only for long-term age but also for short-term age. The purpose is to provide a chemical backfill material and a backfill construction method.

[0009]

The fluidized backfilling material according to the present invention comprises a fly ash cement type B of 1 and an aluminum clinker of 0.8 to 1.3 in muddy water obtained by adding water to excavated soil and stirring. It is characterized in that a fixed amount of the solidifying material mixed at a ratio of 1 is added according to the soil quality and stirred.

Further, the backfilling method according to the present invention is characterized in that the fluidized backfilling material is poured into the backfilling portion for filling.

[0011]

In order to use the excavated soil as a backfill material for backfilling when burying gas pipes, water pipes, etc., it is necessary to increase the strength of the backfill material to a strength equal to or higher than the ground strength. For the strength of this backfill material, it is necessary to increase not only the strength in the long-term age but also the initial strength in the short-term age in order to perform the subsequent work smoothly. Also, the rammer
It is necessary to enhance the fluidity of the backfill material in order to uniformly backfill the lower space of the pipe or the narrow space in which the pipe is converging without being tamped with a tamper or the like. In order to meet such a demand, in the present invention, a certain amount of a mixture of fly ash cement type B and an aluminum clinker as a solidifying material is added to and stirred in mud water in which a relatively large amount of water is added and stirred. Backfill material.

That is, a relatively large amount of water is added to the excavated soil to form muddy water which is stirred, and the flowability of the backfill material is increased by utilizing the good flowability of the fly ash. Also,
Ca (OH) ₂ produced by the hydration of cement reacts with fly ash and significantly increases the long-term strength of the backfill material. Further, the extremely high reaction rate of the aluminum clinker is used to increase the initial strength of the backfill material.

This fly ash cement and aluminum
As for the mixing ratio of the aluminum clinker, if the amount of the aluminum clinker is less than a certain ratio, the initial strength becomes insufficient. On the other hand, when the amount of aluminum clinker exceeds a certain ratio, the initial strength increases, but when the setting time decreases, the workability deteriorates and the increase in long-term strength decreases. Further, if the amount of aluminum clinker is higher than a certain ratio, the improvement in long-term strength is reduced. Therefore, the mixing ratio of fly ash cement type B and aluminum clinker is changed to fly ash cement B type.
Aluminate clinker is mixed in a ratio of 0.8 to 1.3 to 1 seed.

[0014]

[Example] For example, in order to measure the ground strength of a backfill part made of volcanic ash cohesive soil, undisturbed soil of the ground was sampled and the uniaxial compressive strength qu was measured. Was 1.2 kgf / cm ² . Therefore, in order to backfill the excavated soil with a backfill material without tampering with a rammer or tamper, a solidifying material is added while increasing the fluidity by adding a relatively large amount of water to the excavated soil. As a mixture of fly ash cement type B and an aluminum clinker, a mixture ratio of excavated soil, water and solidifying material satisfying the ground strength was investigated. The type B fly ash cement is used here because the type B fly ash cement is workable, has good water-tightness, and is particularly well hardened in water, and is therefore widely used in general civil engineering and construction work. It is easy to obtain.

A relatively large amount of water is added to excavated soil having a natural water content of 135% of volcanic ash cohesive soil and mixed for 1 minute to obtain muddy water having an adjusted water content of 320%, which is shown in FIG. 1, for example. The strength change of the backfill material made by adding the solidifying material consisting of the mixture of the chemical composition fly ash cement type B and the aluminum clinker and mixing for 1 minute is shown in FIG.
Shown in. In FIG. 2, A is fly ash cement B
In the case of a backfill material in which 20% by weight of a solidifying material prepared by mixing a seed and an aluminum clinker in a mixing ratio of 1: 1 was mixed with 20% by weight of mud water having a adjusted water content of 320%, B was When strong portland cement is used, C shows the case where ordinary portland cement is used.

As shown in FIG. 2, in the case of a backfill material using a solidifying material obtained by mixing fly ash cement type B and an aluminum clinker at a mixing ratio of 1: 1, uniaxial in 30 minutes of age. compressive strength qu about 0.6 kgf / cm ^2, 28 days material age uniaxial compressive strength qu is the 4.5 kgf / cm ² or so, the uniaxial compressive strength qu 3 hours material age of about 1.3 kgf / cm ² degree and the natural ground Reached strength. On the other hand, in the case of early strength Portland cement, 28
The uniaxial compressive strength qu is about 4.5 kgf / cm ^{2 in the} Japanese wood age, which is equivalent to the case where the solidified material in which the fly ash cement class B and the aluminum clinker is mixed is used, but the uniaxial compression strength is used in the 3 hour age. The strength qu is about 0.3 kgf / cm ² , and the initial strength is relatively small. Also, in the case of ordinary Portland cement, the unconfined compressive strength qu is about 1.2 kgf / cm ² at 28 days of age, and the unconfined compressive strength qu is about 0.5 kgf / cm ² at 1 day of age. Both the long-term strength and the short-term strength are much smaller than when the solidifying material containing the fly ash cement type B and the aluminum clinker is used. Therefore, even if a relatively large amount of water is added to increase the fluidity and muddy water is added, fly ash cement B
Sufficient strength can be obtained from the initial strength by using the solidifying material in which the seed and the aluminum clinker are mixed.

Next, the solidifying material in which the mixing ratio of the fly ash cement type B and the aluminum clinker was changed was 2% by weight of volcanic ash cohesive soil and muddy water with an adjusted water content of 320%.
The change in strength of the backfill material mixed with 0% added is shown in FIG. In FIG. 3, A is the case where the mixing ratio of the fly ash cement type B and the aluminum clinker is 1: 1, and B is the case where the mixing ratio of the fly ash cement type B and the aluminum clinker is 1: 0.8. C is the case where the mixture ratio of fly ash cement type B and the aluminum clinker is 1: 1.3, D is the case where the mixture ratio of fly ash cement type B and the aluminum clinker is 1: 0.5, E is the fly ash. The case where the mixing ratio of cement type B and aluminum clinker is 1: 1.5 is shown.

As shown in FIG. 3, when a solidifying material having a mixing ratio of fly ash cement type B and an aluminum clinker in the range of 1: 0.5 to 1: 1.3 was used, it was uniaxially compressed at 28 days of age. Although the strength qu is 3.0 kgf / cm ² or more, the long-term strength is greatly improved, but when the mixing ratio of fly ash cement class B and aluminum clinker is 1: 1.5, the uniaxial compressive strength qu is 28 days old. However, the improvement in long-term strength is small, at around 2.0 kgf / cm ² . This is related to the fact that Ca (OH) ₂ generated by the hydration of cement reacts with fly ash to increase the long-term strength.

Further, the uniaxial compressive strength qu increases with the age of 30 minutes or 1 hour as the amount of aluminum clinker increases. The reason why sufficient strength can be obtained from the initial strength is that the reaction rate of the aluminum clinker is extremely high. In particular, when the ratio of aluminum clinker is 0.8 or more, the uniaxial compressive strength qu is 0.3 kgf / cm ² or more in the 30-minute age, and it reaches the natural strength in the 1-hour age. Thus, the uniaxial compressive strength qu
If it is 0.3 kgf / cm ² or more, the strength will not hinder the worker from riding in the backfilled place, and the waiting time for subsequent work can be greatly shortened.

Therefore, 20% by weight of a solidifying material in which the mixing ratio of fly ash cement type B and an aluminum clinker was changed was added to mud water having an adjusted water content ratio of 320%, and the mixture was stirred and the fluidity was examined. When it was stirred for 1 minute, the viscosity was small and the flowability was good, but when the mixing ratio of fly ash cement type B and aluminum clinker was 1: 1.8, the viscosity was high when it was stirred for 3 minutes. As a result, the fluidity has deteriorated. It is considered that the fly ash, which is spherical fine particles contained in the fly ash cement, acts as a lubricant in the backfill material to enhance the fluidity and suppress the rapid hardening of the aluminum clinker.

From these results, a relatively large amount of water was added to the excavated soil made of volcanic ash cohesive soil to adjust the water content ratio to 320%.
Muddy water, and the mixing ratio of fly ash cement type B and aluminum clinker in this muddy water is 1: 0.8 to 1: 1.3.
20% by weight of the solidifying material is added and mixed for about 1 minute,
A backfill material with very good fluidity and strength could be obtained. By pouring this backfill material into the excavation groove in which the pipe was arranged, it was possible to uniformly fill the lower part of the pipe and the gap where the pipe was converging.

In the above embodiment, the case of using the excavated soil made of volcanic ash cohesive soil was explained.
Even when using excavated soil consisting of silt and sandy soil, by adjusting the addition amount of solidifying material according to the strength of the soil,
It is possible to obtain a backfill material having good fluidity and strength as in the above-mentioned Examples.

[0023]

As described above, according to the present invention, a certain amount of a mixture of fly ash cement type B and an aluminum clinker as a solidifying agent is added to and stirred in muddy water obtained by adding a relatively large amount of water to excavated soil and stirring. Since it is a backfill material, it is possible to increase the fluidity of the backfill material by taking advantage of the good fluidity of the fly ash while adding a relatively large amount of water to the excavated soil to create muddy water. And tamper
It can be backfilled without being tampered with, etc., and it can be filled evenly in the lower part of the pipe or in a narrow void by backfilling.

The initial strength of the backfill material can be increased by the solidifying material aluminum clinker, and the mixing ratio of fly ash cement and aluminum clinker is 1 for fly ash cement type B. On the other hand, by mixing the aluminum clinker in the ratio of 0.8 to 1.3, the uniaxial compressive strength qu can be increased to 0.3 kgf / cm ² or more at the age of 30 minutes, and the waiting time for the subsequent work is greatly increased. Can be shortened to

Further, by adjusting the mixing ratio of the fly ash cement and the aluminum clinker at a ratio of 0.8 to 1.3 for the fly ash cement type B to 1 for the fly ash cement type B, a long-term backfill material is used. It can significantly increase the strength in age.

Furthermore, since both the initial strength and the long-term strength of the entire backfill portion can be increased, the construction period of the pipe burying work can be shortened and the backfill portion can be prevented from being depressed. .

Further, since the excavated soil is used as the backfill material, it is not necessary to transport the excavated soil to an inland receiving site or the like, and the construction cost can be greatly reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing chemical components of fly ash cement type B and an aluminum clinker.

FIG. 2 is a strength change characteristic diagram of a backfill material.

FIG. 3 is a strength change characteristic diagram of a backfill material when a solidifying material having a different mixing ratio of fly ash cement type B and an aluminum clinker is used.

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Claims (2)

[Claims] 1. A fixed amount of solidifying material, which is a mixture of fly ash cement type B and aluminum clinker at a ratio of 0.8 to 1.3, is added to mud water, which is prepared by adding water to excavated soil, in a certain amount depending on the soil quality. A fluidized backfill material characterized by being stirred by stirring. 2. A backfilling method, wherein the fluidized backfilling material is poured and filled into a backfilling portion.