JPH0617415A - Fluidization backfill and backfilling method - Google Patents

Abstract

PURPOSE:To increase workability by adding a specified amount of gypsum, jet fine powder, and Portland cement to the muddy water made by adding water to dug soil, and filling it to a backfilling section. CONSTITUTION:A relatively large amount of water is added to dug soil to form muddy water. Next, a hydraulic solidification agent with a mixing ratio of 70:5:25 of gypsum, jet fine powder, and Portland cement is added and mixed with the muddy water. It is poured into a backfilling section in a short time to fill it evenly also into the underside of pipes and narrow spaces. Thus, it can be filled also into narrow spaces without tamping, the strength of the backfilling section can be increased, the work period can be reduced, and the work cost can be reduced remarkably because dug soil is used.

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, the excavated earth and sand are transported to the inland receiving land and sea landfill, and backfilled with mountain sand without using the excavated earth and sand, or placed the excavated earth and sand around the excavation trench, It is transported to a temporary storage site and stored, and after piping, solidification material is added to the excavated soil to backfill it.

[0003]

However, when backfilling with only the sand without using the excavated earth and sand, it is said that due to the regulation of acceptance of the excavated earth and sand, the receiving place of the excavated earth and sand will be reduced in the future and the quality of the sand and sand will be insufficient. There's a problem.

Further, in the case of backfilling, the improved soil obtained by adding a solidifying material to the excavated soil and the mountain sand are 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. In this way, if the wedge part becomes insufficiently compacted, the buried part may be depressed, or if the buried pipe is a humor pipe or a ceramic pipe, the joint part may come off and a damage accident may occur. There is.

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.

[0006] In order to solve such disadvantages, a backfill material is mixed in excavated soil with a solidifying material of several% to 10%, and a certain amount of water is added to the excavated groove to provide a certain degree of fluidity to the excavation trench. A pouring method is disclosed in, for example, Japanese Patent Laid-Open No. 1-312118.

However, according to this method, even if the type of ground is volcanic ash cohesive soil, the mixing ratio of excavated soil, solidifying material and water is 100; 13; 30, the amount of solidifying material is small, and the strength is low. Although it is stated that it is about 2.7 kgf / cm ² in 28-day age, it is not clear because the strength in short-term age such as 30-minute age is not shown.

The present invention has been made in order to improve the above points, and it is possible to easily fill the lower portion of the buried pipe, and it is possible to fill the fluidized backfill material and the backfill material having sufficient strength even for a short period of time. The purpose is to provide a return construction method.

[0009]

The fluidized backfilling material according to the present invention is a hydraulic solidifying material prepared by mixing gypsum, jet fine powder and Portland cement in muddy water obtained by adding water to excavated soil and stirring the material. It is characterized in that a certain amount was added and stirred.

The mixing ratio of gypsum, jet fine powder and Portland cement as the hydraulic setting material is preferably 70; 5; 25.

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

[0012]

[Operation] When burying gas pipes, water pipes, etc., the excavated soil is used as a backfill material, and it is uniformly filled in a narrow space where the lower part of the pipe or the pipe is congested without being tampered with a rammer or tamper. In order to restore it, it is necessary to mix an appropriate amount of water with the excavated soil to increase the fluidity and to mix the solidifying material to increase the strength to be equal to or higher than the ground strength. Therefore, in the present invention, a relatively large amount of water is added to the excavated soil to make it agitated mud water, the fluidity is enhanced, and the fluid is poured into the backfilling portion in a short time, and the lower part of the pipe and narrow voids are evenly filled.

The muddy water is mixed with a hydraulic solidifying material to enhance the strength of the backfilled portion. As this hydraulic setting material, gypsum, jet fine powder and Portland cement 70; 5; 25
The strength of the backfill material using excavated soil is increased in a short time by using the material mixed in the ratio of.

[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, etc., a relatively large amount of water is added to the excavated soil to increase fluidity and Using a mixture of gypsum, jet fine powder made of a mixture of dephosphorized slag, fluorite, lime and aluminum ash, and Portland cement as a solidifying material, excavated soil, water and hydraulic solidifying material satisfying the ground strength. The compounding ratio of was investigated.

Consisting of volcanic ash cohesive soil with a natural water content of 135
% Excavated soil with a relatively large amount of water and mixed for 1 minute to make muddy water with an adjusted water content ratio of 300%. FIG. 1 shows the result of examining the strength change of the backfill material prepared by mixing the hydraulic solidifying material with the compounding ratio of S; J; C = 70; 5; 25 for 1 minute while changing the addition rate. In FIG. 1, A is a solidifying agent addition rate of 25% by weight relative to muddy water with an adjusted water content of 300%, B is a solidifying agent addition rate of 20%, and C is a solidifying agent addition rate of 15%. % Is the case. As shown in Figure 1,
When the solidifying material addition rate is 15%, the uniaxial compressive strength qua is about 0.8 kgf / cm ² at 30 minutes of age, and the uniaxial compressive strength qua is 1 kg at 28 days of age.
f / cm ² and no increase in strength, 1.2 kgf / cm of natural strength
Did not reach ² . Also, if the solidified material addition rate is 20%, a uniaxial compressive strength qu about 1.3 kgf / cm ^2, the uniaxial compressive strength qu 28 days material ordinance 2.5 kgf / cm ² about 30 min material age, 30 Although it exceeds the natural strength of 1.2 kgf / cm ² from the division age, it was about the strength of the ground for 2 hours and 1 day. When the solidifying material addition rate is 25%, the uniaxial compressive strength qu is about 2.3 kg at 30 minutes of age.
The uniaxial compressive strength qu is about 3.8 kgf / cm ² at f / cm ² and 28 days old, and is about twice as much as the ground strength at 30 minutes old, and more than 3 times as strong as the 28 days old age. It was possible to obtain a strength that exceeded or exceeded the initial strength. Therefore, even if a relatively large amount of water is added to make it muddy to improve fluidity, it is possible to obtain sufficient strength from the initial strength by adding 20% or more of the solidifying material.

Therefore, the results of examining the change in strength of the backfill material by changing the adjusted water content ratio by setting the addition rates of the solidifying material to 20% and 25% are shown in FIG. In Fig. 2, A is the adjusted water content of mud mixed with excavated soil and water, and the addition rate of solidifying material is 25%.
%, B is 20% in the same condition under the same conditions, and C is 325% in the adjusted water content and 2% in the solidification ratio.
In the case of 5%, D has an adjusted water content ratio of 325% and the addition rate of the solidifying material is
It is the case of 20%. As shown in FIG. 2, even if the addition rate of the solidifying material is the same, when the adjusted water content ratio increases from 300% to 325%, the uniaxial compressive strength qu sharply decreases. Therefore, it is appropriate that the adjusted water content is about 300% at maximum.

Therefore, FIG. 3 shows the results of examining the strength change of the backfill material when the adjusted water content ratio is 300%, the solidification material addition rate is 25%, and the raw material blending ratio of the solidification material is changed. Figure 3
In A, the raw material mixture ratio of the solidifying material is S; J; C = 70;
In the case of 5; 25, B shows the case of S; J; C = 60; 10; 30. As shown in the figure, when the raw material mixture ratio of the solidifying material is S; J; C = 60; 10; 30, the uniaxial compressive strength qu becomes about 8.8 kgf / cm ² at the age of 28 days, but 30 The uniaxial compressive strength q u was about 1.5 kgf / cm ² in the parting age, and the initial strength was better when the raw material mixture ratio of the solidifying material was S; J; C = 70; 5; 25. This is gypsum (S) when the initial strength appears
The effect of the jet fine powder (J) and Portland cement (C) will be exerted in the long term. Therefore, in order to obtain stable strength from the initial strength, the raw material mixture ratio of the solidifying material is S; J; C.
= 70; 5; 25 is preferable.

In this way, the raw material mixing ratio is S; J; C = 7.
Adjust the solidifying material to 0; 5; 25 to 25% in muddy water with a water content of 300%.
When added, stable strength can be obtained from the initial strength. Therefore, water is added to the excavated soil and mixed for 1 minute to make muddy water with an adjusted water content ratio of 300%, and the strength of the backfill material when the stirring time is changed when 25% of the solidifying material is added to this muddy water and mixed. The result of examining the change is shown in FIG. In FIG.
When A is a stirring time of 1 minute when the solidifying material is added,
Indicates the case where the stirring time is 5 minutes. As shown in the figure, when agitating for 5 minutes, both the initial strength and the strength of the long-term material are lower than those of 1 minute. This phenomenon requires a solidifying agent addition rate of 20.
The same occurs when changing to%. It is considered that this is because the fluidized soil, which has already started to harden, is disturbed by stirring for 5 minutes. Further, when the mixture was stirred for 1 minute, the viscosity was small and the fluidity was very good, but when the mixture was stirred for 5 minutes, the viscosity was high and the fluidity was poor. Therefore, the stirring time when the solidifying material is added should be within 5 minutes.

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 to 300%.
And the mixing ratio of gypsum (S), jet fine powder (J) and Portland cement (C) to this muddy water is S;
When 25% of the hydraulic solidifying material with J; C = 70; 5; 25 was added and mixed for about 1 minute, a backfilled material having very good fluidity and strength could be obtained. Then, by pouring this backfill material into the excavation groove in which the pipe was arranged, it was possible to uniformly fill the lower portion 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.
The same can be applied when using excavated soil composed of silt or sandy soil.

[0021]

As described above, according to the present invention, since a relatively large amount of water is added to excavated soil to make muddy water which is stirred to improve the fluidity and to be poured into the backfill portion, a rammer, a tamper, etc. It can be backfilled without being tampered with, and can be filled evenly in the lower part of the pipe or in a narrow space by backfilling.

Further, the strength of the entire backfilled portion is increased from the initial stage by mixing the muddy water with the hydraulic solidifying material obtained by mixing gypsum, jet fine powder and Portland cement at a ratio of 70: 5; 25 at a predetermined addition rate. Therefore, the construction period 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 a strength change characteristic diagram of a backfill material when an addition rate of a solidifying material is changed.

FIG. 2 is a strength change characteristic diagram of the backfill material when the adjusted water content ratio is changed.

FIG. 3 is a strength change characteristic diagram of the backfill material when the raw material mixture ratio of the solidified material is changed.

FIG. 4 is a strength change characteristic diagram of the backfill material when the stirring time of the solidified material is changed.

Claims (3)

[Claims] 1. A fluidized embedding characterized by adding a fixed amount of a hydraulic solidifying material obtained by mixing gypsum, jet fine powder and Portland cement to muddy water obtained by adding water to excavated soil and stirring the mixture. Return material. 2. The fluidized backfill material according to claim 1, wherein the compounding ratio of gypsum, jet fine powder and Portland cement as the hydraulic setting material is 70; 5; 25. 3. A backfilling method, comprising pouring and filling the fluidized backfilling material according to claim 1 into a backfilling portion.