JPH0995949A - Back filling construction method for buried pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back filling construction method which uses inexpensive fluidized earth being generally combined, and can deposit an upper layer part such as a road bed within specified time after depositing a fluidized earth layer. SOLUTION: In a back filling construction method for back filling various buried pipes which are buried or constructed under the surface of the ground, after depositing the fluidized earth layer 1 composed of fliuidzied earth from the lower end of the buried pipe 3 to height more than 1/5 of the diameter of the buried pipe 3, an earth and sand layer 2 composed of the earth and sand is provided on the fluidized earth layer 1 so that an earth and sand layer 22 composed of only the earth and sand having a fixed layer thickness necessary for compaction may be formed on a mixed layer 21 composed by mixing the earth and sand and the fluidized earth. After compacting of the earth and sand layer 2, an upper layer part such as a road bed is executed.

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 underground buried pipes such as gas pipes and communication cables.

[0002]

2. Description of the Related Art Conventionally, as a backfill material used when backfilling an underground buried object, in many cases, good quality sand or the like collected from another place is used. This is because excavated soil generated during the laying of underground buried objects is rarely suitable for backfill materials.

In recent years, from the viewpoints of depletion of high-quality mountain sand, which is a natural resource, environmental damage due to its extraction, traffic pollution due to its transportation, and disposal problems of excavated soil, excavated soil and construction unsuitable as backfill materials. There is a growing movement to effectively utilize sludge and other bad soil.

In the conventional backfilling method in which a backfill material such as high quality sand is directly used, in order to prevent depression after backfilling, the backfill material is filled in a narrow area such as a peripheral portion of the buried object without any gap. Sufficient compaction with a rammer is required. However, in this conventional method, filling of the backfill material and compaction by a rammer are all manual work, and there is a problem that noise and vibration are caused.

Recently, instead of using a special backfill material such as the above-mentioned high quality mountain sand, excavated soil or cheap earth and sand generated when laying an embedded object is used, and the problems of the conventional method as described above. A fluidized backfilling method that can solve the problem has been developed and is partly in practical use. This method mixes water and solidifying material with excavated soil or cheap earth and sand, makes the backfill material fluid, and fills narrow spaces such as the periphery of buried objects without any gaps. It is intended to develop strength equal to or higher than that of the natural ground.

[0006] For example, Japanese Patent Laid-Open Nos. 63-233115, 1-312118, and 4-351.
No. 388 discloses a method in which water and a solidifying material are mixed with earth and sand, and the resulting soil is used for backfilling a buried pipe or the like as fluidized soil having fluidity.

Further, in Japanese Patent Laid-Open No. 3-287909, the excavated soil is mixed with a solidifying material in advance, and the treated soil is transported to the backfill site, and water is poured into the treated soil while backfilling and vibration is applied. A method of fluidizing and completely filling the backfilled portion is disclosed.

On the other hand, in the road occupancy work on the city streets, where the gas burial piping work and the like occupy the majority,
Since it is unavoidable to construct it under the condition that the traffic can be opened on the same day, short-time backfilling work is essential. In particular, when the fluidized backfilling method as described above is used, it is required that the upper layer portion such as the roadbed can be constructed within 2 hours after the fluidized soil layer is cast.

[0009]

However, in the fluidization backfilling method disclosed in the above-mentioned patent publication, it is necessary to wait until the fluidized soil solidifies until the fluidized soil has a strength capable of constructing an upper layer portion such as a roadbed. It usually has to be 4
As it is ~ 5 hours long, we cannot deal with the same day restoration work in urban areas.

If a special solidifying material is used according to the fluidized soil, the solidifying time is shortened, but the cost is high and the compounding technique is complicated, so that strict quality control is required.

The present invention has been made in order to solve the above problems, and uses inexpensive general fluidized soil having a general composition, and moreover, within 2 hours after placing the fluidized soil layer, the upper layer of a roadbed or the like. It is an object of the present invention to provide a backfilling method for buried pipes capable of constructing a section.

[0012]

[Means for Solving the Problems] In the backfilling method for backfilling various buried pipes buried or constructed under the ground surface, the above-mentioned problem is 1 / one of the diameter of the buried pipe from the lower end of the buried pipe.
After pouring a fluidized soil layer made of fluidized soil to a height of 5 or more, a sediment layer made of earth and sand is placed on the fluidized soil layer on a mixed layer formed by mixing the soil and the fluidized soil. Set up so that a sediment layer with a predetermined layer thickness necessary for compaction is formed, and after compacting the sediment layer, the upper layer part such as the roadbed is constructed and solved by the backfilling method of the buried pipe To be done.

By pouring a fluidized soil layer made of fluidized soil from the lower end of the buried pipe to a height of ⅕ or more of the diameter of the buried pipe, generation of voids around the lower end of the buried pipe can be prevented, Can be backfilled with good filling property. If it is less than ⅕, it may be dented after construction due to voids generated around the lower end of the buried pipe.

After forming the fluidized soil layer, when a sediment layer made of earth and sand is formed on the fluidized soil layer, the earth and sand layer will be a mixed layer of earth and fluidized soil and earth and sand only on the mixed layer. It has a two-layer structure with layers. At this time, if the layer thickness of the earth and sand layer consisting of only the earth and sand is a predetermined layer thickness, the load distribution effect will not cause the fluidized soil to solidify and the strength of the fluidized soil layer to increase without waiting Since the layers can be compacted, backfilling in a short time is possible.

The layer thickness required for compaction of the sediment layer consisting of only the sediment depends on the type and characteristics of the sediment, and if it is thin, it will be difficult to compact because of the large amount of water absorbed from the fluidized soil layer. If too much, compaction cannot be performed sufficiently. Therefore, it is necessary to appropriately determine in advance the optimum layer thickness, that is, the optimum amount of earth and sand input.

When the soil-hardening material contains a water-curable material, water-absorbing water from the fluidizing soil layer hardens the water-hardening material in the soil-sand layer, so that the fluidized soil is solidified and the fluidized soil layer has high strength. There is no need to wait for it to become dry, and the work of compacting this layer of sand is also unnecessary. Therefore, backfilling can be performed in a shorter time.

The amount of the water-curable material contained in the earth and sand is
If the amount is too large, the long-term strength will be too high, making it difficult to re-excavate, and if it is too small, the strength will be insufficient.
It needs to be 0%.

Further, when water is sprinkled on the earth-and-sand layer containing the water-curable material, the water-curable material can be hardened from the upper part of the earth-and-sand layer, so that backfilling can be performed in a shorter time.

By repeatedly forming the sediment layer containing the water-curable material and sprinkling water on the sediment layer, it is not necessary to place a new subgrade, and the upper layer such as a roadbed is directly placed on the sediment layer. Since the parts can be constructed, it is possible to backfill in a shorter time. It is necessary to appropriately determine the number of layers of earth and sand depending on the installation conditions of the buried object, the type of earth and sand, and the water-curable material.

It is desirable that the water-curable material is gypsum, a fast-setting cement or a solidifying material because the curing rate is accelerated.

It is desirable that the water-curable material is cement containing a quick-setting agent, because the curing rate is further accelerated.

The water content of the sand containing the water-curable material is such that when the water-curable material is mixed, it reacts with the water-curable material to solidify the water-curable material or to condense the water-curable material to form a lump. It is desirable to keep the surface dry condition or less so as not to cause the above.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of an embodiment of a backfilling method for a buried pipe according to the present invention. In the figure, 1 is a fluidized soil layer,
2 is a sediment layer, 21 is a mixed layer of fluidized soil and sediment, 22 is a sediment layer consisting only of sediment, 3 is a buried pipe such as a gas pipe, 4 is a roadbed, 5 is a roadbed, 6 is pavement, 7 is ground The surface, 8 is a steel sheet pile for retaining soil.

FIG. 2 shows another example of the embodiment of the backfilling method for a buried pipe according to the present invention. The numbers in the figure represent the same as the numbers shown in FIG.

FIG. 1 shows a case where there is one buried pipe 3, whereas FIG. 2 shows a case where there are two buried pipes 3 in parallel and two stages above and below, a total of four. In the case of FIG. 2, the diameter of the upper buried pipe 3 is 1
It is necessary to fill with fluidized soil to a height of / 5 or more.

As the earth and sand to be put on the fluidized soil layer 1,
It is possible to use ordinary earth and sand that is inexpensive and easily available, for example, ordinary mountain sand.

As the water-curable material contained in the earth and sand,
Various cements, solidifying materials, gypsum, quick lime, fly ash, granulated blast furnace slag and the like can be used, but as described above, it is preferable to use gypsum, fast-setting cement or solidifying material.

The amount of water sprayed when water is sprayed on the earth and sand layer 2 containing a water-curable material needs to be determined from the viewpoint of short-term strength and long-term strength of the layer 2. The appropriate amount changes depending on the amount. As a guide, in the case of sand, a water content of about 15 to 20% is preferable. Thus, by spraying water on the earth and sand layer 2 containing the water-curable material, the layer 2 itself hardens, so that compaction work is unnecessary.

By providing several layers of earth-and-sand layer 2 containing a water-curable material while sprinkling water thereon, it is possible to omit placing a new roadbed 4 and directly construct an upper layer portion such as a roadbed 5. Become.

[0030]

【Example】

(Example 1) After burying a gas pipe having a diameter of 200 mm under the ground surface as in the example shown in FIG. 1, from the lower end of the gas pipe to a height corresponding to ¼ of the diameter, shown in Table 1 Fluidized soil having a specific composition was placed at 0.14 t / m. Immediately thereafter, the sand with a water content of 10% and a specific gravity of 2.7 was added to the fluidized soil layer.
5 t / m was charged, the surface was leveled, and compacted with a rammer. Then, the upper layers such as the subgrade were constructed. At this time, the time from the pouring of the fluidized soil layer to the start of construction of the upper layer portion such as the roadbed was about 30 minutes, which was shortened by 4 hours or more as compared with the conventional method. The strength of the mixed layer of fluidized soil and mountain sand after 28 days was 1.8 kgf / cm ² in uniaxial compressive strength, and was a strength capable of being re-excavated.

(Example 2) The diameter is 50 m below the ground surface.
2 communication cables in parallel as in the example shown in FIG.
After burying a total of four, two in the upper and the other in the upper and lower parts, 0.2 parts of the fluidized soil of the general composition shown in Table 1 up to the upper end of the upper communication cable.
4t / m was placed. Immediately after that, the fluidized soil layer immediately contained 4% by weight of ordinary Portland cement and had a water content of 3
% Air-dried mountain sand was added at 0.5 t / m, and water was evenly sprayed thereon so that the water content ratio was 15 to 20%.
Subsequently, the same pile of sand mixed with cement and water sprinkling were repeated twice to construct the upper layer of the roadbed. At this time, the time from the pouring of the fluidized soil layer to the start of construction of the upper layer portion such as the roadbed was about 50 minutes. The strength of the cement mixed pile sand layer after 28 days was uniaxial compressive strength of 2.
At 0 kgf / cm ² , the strength was such that re-excavation was possible.

[0032]

[Table 1]

[0033]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, even if an inexpensive fluidized soil having a general composition is used,
It is possible to provide a backfilling method for a buried pipe that enables construction of an upper layer portion such as a roadbed within the time.

Further, when the backfilling method of the present invention is used, the backfilling work can be completed before the entire fluidized soil layer is completely solidified, so that the steel sheet pile for retaining soil can be easily pulled out, and After drawing the steel sheet pile, there is no gap between the fluidized soil layer and the ground, so no ground deterioration occurs.

[Brief description of drawings]

FIG. 1 is a first embodiment of a method for backfilling a buried pipe according to the present invention.
It is a figure showing an example.

FIG. 2 is a diagram showing another example of the embodiment of the backfilling method for the buried pipe of the present invention.

[Explanation of symbols]

 1 fluidized soil layer 2 earth and sand layer 21 mixed layer of fluidized soil and earth and sand 22 earth and sand layer 3 earth and sand layer 3 buried pipe such as gas pipe 4 roadbed 5 roadbed 6 pavement 7 ground surface 8 steel sheet pile for retaining soil

Claims (7)

[Claims] 1. In a backfilling method for backfilling various buried pipes buried or constructed under the surface of the earth, fluidized soil is formed from the lower end of the buried pipe to a height of ⅕ or more of the diameter of the buried pipe. After pouring the fluidized soil layer, a layer of earth and sand consisting of earth and sand on the fluidized soil layer, a predetermined layer thickness necessary for compaction on a mixed layer formed by mixing the earth and sand and the fluidized soil Provided so that a layer is formed, after compacting the sediment layer,
A method of backfilling buried pipes, which is characterized by constructing the upper layer of the subgrade. 2. In a backfilling method for backfilling various buried pipes buried or constructed under the surface of the ground, fluidized soil is formed from the lower end of the buried pipe to a height of ⅕ or more of the diameter of the buried pipe. After placing the fluidized soil layer, a layer of earth and sand containing 3 to 20% by weight of a water-curable material is provided on the fluidized soil layer, and an upper layer portion such as a roadbed is constructed. The backfilling method for buried pipes characterized by. 3. The backfilling method for a buried pipe according to claim 2, wherein after providing a sediment layer made of sediment containing the water-curable material, water is sprinkled on the sediment layer. 4. A backfilling method for backfilling various buried pipes buried or constructed under the surface of the earth, comprising fluidized soil from the lower end portion of the buried pipe to a height of ⅕ or more of the diameter of the buried pipe. After pouring the fluidized soil layer, a layer of earth and sand containing 3 to 20% by weight of a water-curable material on the fluidized soil layer is sprinkled onto the layer of sand to form a predetermined layer. A backfilling method for buried pipes, characterized in that a number of them are provided and the upper layer of the roadbed is constructed. 5. The method of backfilling a buried pipe according to claim 2, wherein the water-curable material is gypsum, a fast-setting cement or a solidifying material. 6. The method according to claim 2, wherein the water-curable material is cement containing a quick-setting agent.
The method of backfilling the buried pipe described in. 7. The backfilling method for a buried pipe according to claim 2, wherein the water content of the soil containing the water-curable material is not more than a surface dry state. .