JPH1150438A - Superplasticization backfilling method of buried substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the superplasticization backfilling method of an inexpensive buried substance capable of opening traffic within 2 hours after superplasticization soil layer placing. SOLUTION: With regard to the superplasticization backfilling method of buried substances, the various buried substances 3 buried or constructed under ground surface are backfilled by means of superplasticization soil. A superplasticization soil layer 1 is placed on the circumference of the buried substances 3, a soil and sand layer 2 composed of a particle diameter of 6-5 mm in 90% or more by weight ratio is provided on a superplasticization soil layer 1. After solidification liquid mixing solidification material containing 0.5-2 cement to 1 gypsum by weight ratio and 2-3 waten to 1 solidification material is sprayed on the soil and sand layer 2, an upper layer such as a subgrade 4 is placed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for backfilling a buried object such as a gas pipe or a communication cable, and more particularly to a method for backfilling a buried object using fluidized soil as a backfill material.

[0002]

2. Description of the Related Art In recent years, from the viewpoints of depletion of high-quality mountain sand, which is a natural resource, environmental destruction due to its extraction, traffic pollution due to its transportation, and disposal of excavated soil, it has been considered unsuitable as a backfill material. There is a growing movement to make effective use of excavated soil, construction sludge, and other poor soil.

For example, JP-A-63-233115, JP-A-1-312118, and JP-A-4-351
No. 388 discloses fluidization of a buried object in which a fluidized soil obtained by adding water to such excavated soil or defective soil and having fluidity is filled around the buried object and then an upper layer portion such as a roadbed is poured. A backfill method has been proposed and some have already been implemented. In this method, fluidized soil is used as backfill material, so it can not only fill the narrow part around the buried pipe easily, but also solidifying material is added at the same time as water, so the strength is equal to or higher than the ground. Can be expressed.

Japanese Patent Application Laid-Open No. 3-287909 discloses a method in which a solidified material is mixed in advance with excavated soil, transported to a site for backfilling, and vibrated while being injected with water during backfilling. Also, a fluidized backfill method for filling into a container is disclosed.

On the other hand, in the occupation of roads on urban streets where gas burial and plumbing work occupies most of the work, it is inevitable that the work be carried out under the condition of opening traffic on the same day. Has become. In particular, when using the fluidized backfill method as described above, it is required that traffic can be opened within two hours after the fluidized soil layer is cast.

[0006]

However, in the fluidized backfill method disclosed in the above-mentioned patent gazettes, the solidification time of the fluidized soil is as long as 4 to 5 hours, and the solidification time of the fluidized soil layer is 2 hours. We cannot respond to opening of traffic within hours. The use of a special hardening material shortens the hardening time, but increases the cost and hardens too quickly to make the construction management difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an inexpensive fluidized backfilling method for buried objects which can be opened to traffic within two hours after placing the fluidized soil layer. The purpose is to provide.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a fluidized backfill method for burying or burying various buried objects buried or constructed under the ground surface using fluidized soil. A fossilized soil layer is cast, and a sedimentary layer comprising particles having a particle size of 0.6 to 5 mm in a weight ratio of 90% or more is provided on the fluidized soiled layer, and gypsum 1 is weighted on the sedimentary layer. Buried object in which an upper layer portion such as a roadbed is poured after spraying a solidified liquid obtained by mixing a solidified material containing cement of 0.5 to 2 and a water of 2 to 3 with respect to the solidified material 1 in a weight ratio. Solved by the fluidized backfill method.

As described above, unless a special solidifying material is used, the fluidized soil layer cannot be solidified in a short time, and the traffic cannot be opened within two hours after the fluidized soil layer is cast. Therefore, the present inventors have studied a method that enables the casting of an upper layer such as a subgrade without waiting for the solidification of the fluidized soil layer. If a solidified solution containing a solidified material containing gypsum and cement in an appropriate ratio and water mixed in an appropriate ratio is sprayed on the layer, the solidified solution penetrates and this soil layer can be passed through in a short time. It has been found that the material can be solidified to such an extent that the upper part such as the floor can be cast, and that the traffic can be opened within two hours after placing the fluidized soil layer.

At this time, the earth and sand layer has a weight ratio of 90%.
% Or more needs to be a sediment layer composed of particles having a particle size of 0.6 to 5 mm. If it is finer than this, the solidification liquid becomes difficult to penetrate, and the earth and sand layer cannot be solidified in a short time.

[0011] Similarly, in order to solidify the earth and sand layer in a short time and obtain a long-term strength capable of re-excavation, the ratio of gypsum to cement contained in the solidified material is 0.5 to 1% by weight of gypsum to cement. It is necessary to set the ratio of the solidified material and water in the solidified liquid to 2 to 3 with respect to the solidified material 1 by weight.

[0012] The reason for using a composite of gypsum and cement as a solidifying material is that in the case of only gypsum, if the gypsum is exposed to water for a long time after burying, the strength is reduced and the road may collapse. . The addition of cement can prevent the strength from being reduced, but the excessive addition makes the long-term strength too high and makes re-excavation impossible.

According to the method of the present invention, gypsum and cement, which can be obtained at low cost, are used without using a special solidifying material, so that the cost does not increase.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows one embodiment of a fluidized backfill method of a buried object according to the present invention.

After laying a buried object 3 such as a gas pipe below the ground surface 7, the surrounding area is filled with a fluidized soil composed of, for example, earth and sand, a solidifying material, and water, and a fluidized soil layer 1 is poured into the fluidized soil layer. 90% by ratio
When the sediment layer 2 composed of particles having a particle diameter of 0.6 to 5 mm is provided and a solidifying liquid containing gypsum, cement and water is sprayed on the sediment layer 2, the solidifying liquid penetrates the sediment layer 2 and the sediment layer 2 Is solidified in a short time, so that the upper layers of the subgrade 4, the subgrade 5, and the pavement 6 can be cast in a short time. At this time, if the ratio of the gypsum, cement and water in the solidified liquid is adjusted within the range of the present invention, the burial work can be completed so that the traffic can be opened within two hours after the fluidized soil layer is cast, and the rebuilding work can be completed. Long-term strength enough to excavate can be secured.

The earth and sand used for the earth and sand layer 2 may be ordinary earth and sand which is inexpensive and easily available, for example, ordinary mountain sand and crushed single-grained stone.

The thickness of the earth and sand layer 2 depends on the short-term strength of the earth and sand layer 2,
Although it is necessary to determine from the viewpoint of long-term strength, the appropriate thickness varies depending on the content of gypsum or cement in the solidified liquid sprayed on the earth and sand layer 2 and the amount of the solidified liquid sprayed.

[0018]

EXAMPLE After a gas pipe was placed below the ground surface, a fluidized soil layer composed of fluidized soil shown in Table 1 was cast around the gas pipe, and the strength of the fluidized soil layer was 0.01 kgf in cone index. / Cm ² , the weight ratio of particles having a particle size of 0.6 to 5 mm shown in Table 2 was set to about 200 mm with a weight ratio of 80 and 90%, and immediately gypsum of various formulations shown in Table 2 A solidification solution consisting of cement and water was sprayed. The sediment layer uses two types of soil, dry and wet.
As a result of measurement according to SA1203 (1995), 1.8
And 16.0%. In addition, gypsum is grilled gypsum,
The cement was ordinary Portland cement, the tap water was used as the water, and the solidified liquid was prepared 10 minutes before spraying.

The unconfined compressive strength of the sediment layer after 20 minutes and 28 days was measured according to JIS A 1216 (1993).
It was measured in accordance with the "Soil uniaxial compression test method". In addition, when the relationship between the uniaxial compressive strength after 20 minutes and the time when the traffic was made open after the fluidized soil layer was cast was investigated in advance, the uniaxial compressive strength after 20 minutes was 0.5 kgf / cm ² or more. Then, traffic opening is possible within 2 hours after placing the fluidized soil layer, and the uniaxial compressive strength after 28 days is 3.0 kgf / c.
re-digging if m ² or less was possible.

The results are shown in Table 2. By spraying a solidified liquid composed of gypsum, cement and water in a ratio within the range of the present invention, a soil layer composed of particles having a particle size of 0.6 to 5 mm in a weight ratio of 90% is dispersed in the soil layer. Irrespective of the initial water content, it shows a uniaxial compressive strength of 0.5 kgf / cm ² or more after 20 minutes and a uniaxial compressive strength of 3.0 kgf / cm ² or less after 28 days (Nos. 2, 3, 6). , 7).

If the water content in the solidified liquid is lower than the range of the present invention, the uniaxial compressive strength after 28 days exceeds 3.0 kgf / cm ² (Nos. 1 and 5), and if it is higher, the uniaxial compressive strength after 20 minutes is 0. 0.5 kgf / cm ² or more (No. 4,
8).

In the case of an earth and sand layer in which 80% by weight consists of particles having a particle size of 0.6 to 5 mm, the particle size of the remaining 20% is 0.1%.
When there are many particles smaller than 6 mm, the solidification liquid does not penetrate into the earth and sand layer and the earth and sand layer does not solidify (No. 9). Further, when there are many particles exceeding 5 mm in the remaining 20%, the uniaxial compressive strength after 28 days exceeds 3.0 kgf / cm ² (No. 1).
0).

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

Since the present invention is constructed as described above, it is possible to use an inexpensive fluidized soil of a general composition and to bury the traffic within two hours after placing the fluidized soil layer. An object backfill method can be provided.

Further, if the backfill method of the present invention is used, the backfill work can be completed before the entire fluidized soil layer is completely solidified, so that the steel sheet pile for earth retaining can be easily pulled out, and After the steel sheet pile is drawn, there is no gap between the fluidized soil layer and the ground, so that no land subsidence occurs.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of a fluidized backfill method of a buried object according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 fluidized soil layer 2 earth and sand layer 3 buried object such as gas pipe 4 subgrade 5 subgrade 6 pavement 7 ground surface 8 steel sheet pile for retaining

Claims (1)

[Claims] Claims: 1. In a fluidized backfill method of a buried object in which various buried objects buried or constructed under the ground surface are buried using fluidized soil, a fluidized soil layer is cast around the buried object, 90% or more by weight of the fluidized soil layer has a particle size of 0.6 to 5
and a solidified material containing 0.5 to 2 cements per gypsum at a weight ratio of 2 to 3 water relative to the solidified material 1 at a weight ratio. A fluidized back-filling method for buried objects where the solidified liquid mixed with the above is sprayed and then the upper layer such as the roadbed is cast.