JP2772993B2 - Civil engineering method using foamable resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a civil engineering method for producing a resin foam having a uniform foaming state and compressive strength when foaming resin is foamed to a required shape on site to perform embankment, formation of artificial ground, road widening work, and the like.

[Prior art]

Attempts have been made in the past to make use of the lightweight properties of the foamed resin to fill in depressions or to make them a part of artificial ground. For example, a foamable resin is molded into a foam block having a predetermined shape at a factory, the foam block is piled up on an original ground to be embanked, and a concrete floor plate, a wall protection material and the like are stretched on the surface layer to finish. Further, a reinforcing material such as a reinforcing bar is arranged inside to improve the structural strength. When stacking foam in this way to form the ground,
A gap easily occurs between the foam blocks. Accordingly, Japanese Utility Model Laid-Open No. 63-81941, Japanese Utility Model Laid-Open No. 63-81942, and the like introduce a method of forming irregularities on the surface of a foam block and engaging the irregularities in order to eliminate the deviation. I have. However, the method of transporting the foamed block after foaming at the factory to the site and stacking the foamed block in a predetermined shape takes time and effort to transport and handle. For example, a large block of about 2 × 1 × 0.5 m is used as this type of block, but such a large block requires labor for transportation despite its light weight. In addition, the transportation is substantially as if carrying air, and there is much waste. In addition, as the size of the block becomes larger, it is necessary to prevent the formation of a gap between the block and the block that is laid flat by flattening the original ground on which the work such as embankment is to be performed. Further, Japanese Patent Application Laid-Open No. 47-19617 discloses that an unfoamed resin such as urethane, vinyl chloride, styrene or the like is sprayed on a depression or a roadbed, and then a foaming reaction is performed to fill the depression or the like. ing. However, the publication does not specifically teach how to foam the resin. However, simply foaming the resin often does not have the required contour on the resin body surface after foaming due to uneven foaming or the like. In addition, when foaming is performed at the free interface, the surface strength of the foam is not sufficient, and dents and the like easily occur when a tread pressure is applied.

[Problems to be solved by the invention]

The present inventors, while making use of the advantages of on-site construction, as a method of forming an artificial ground having the required strength, as a method of forming foam, spread beads of foamable resin on the original ground partitioned by a formwork,
A method for constructing artificial ground by foaming resin beads with heated gas was developed. Incidentally, when the ground is constructed by foaming the resin beads, uneven foaming of the resin beads tends to occur. As a result, defects such as generation of irregularities on the surface of the resin body after foaming and generation of internal cavities will occur. Such defects are:
It is presumed to be due to the fluctuation of the foaming atmosphere of the resin beads. Accordingly, the present invention provides a method for constructing an artificial ground made of a resin foam having a uniform foam structure and a compressive strength by uniformly bringing a heating gas into contact with the resin beads to foam the resin beads uniformly. Aim.

[Means for Solving the Problems]

In order to achieve this object, the civil engineering method of the present invention forms a fine-grained layer in which a gas injection pipe is buried on the original ground, and scatters beads made of a foamed resin on the fine-grained layer. A mold is arranged above the beads via a space, and the beads are heated and foamed by a heated gas ejected from the gas injection pipe. As a material of the fine grain layer, sand grains are typically used.
However, if other inexpensive granular materials are easily available, they can be used instead of sand particles.

[Action]

Heated gas such as water vapor ejected from the gas injection pipe is first blown into the fine-grained layer around the gas injection pipe,
Contact the resin beads sprayed on the fine-grained layer. The heated gas is dispersed by the resistance when passing through the fine-grain layer, and is blown to the resin bead layer at a substantially uniform flow rate over the entire fine-grain layer. As a result, the contact between the heated gas and the resin beads is made uniform, and the foaming of the resin beads is performed uniformly over the entire surface. Therefore, local occurrence of the foaming reaction is suppressed, and a resin foam having a uniform foaming state can be obtained.

【Example】

Hereinafter, the present invention will be described in detail with reference to the drawings by using an example applied to embankment of a depression. In the present embodiment, as shown in FIG. 1, a predetermined embankment is formed in a depression 2 formed in the original ground 1. At the bottom of the depression 2, a sand layer 4 in which a gas injection pipe 3 is embedded is provided. The gas injection pipe 3 has a large number of gas ejection holes 3a formed on the peripheral surface thereof, and is connected to an appropriate boiler via an air supply pump. The sand layer 4 in which the gas injection pipe 3 is buried is a gas outlet 3a.
The thickness is set so that the heated gas blown out of the resin layer is sprayed on the sand layer 4 and does not blow directly toward the resin beads 5. Also, due to the resistance of the sand layer 4, the gas ejection holes
The flow rate of the heated gas ejected from 3a is made uniform over the entire length of the gas injection pipe 3. The thickness of the sand layer 4 is determined in consideration of the gas pressure in the gas injection pipe 3, the diameter of the gas injection hole 3 a, the diameter of the gas injection pipe 3, and the like. The intended purpose can be achieved when the distance from the upper peripheral surface to the surface of the sand layer 4 is about 1 to 5 cm. Next, a procedure for forming a ground with a resin foam using this apparatus will be described. A styrene resin having an average particle size of 0.9 mm was used as the resin beads. This resin starts a foaming reaction in relation to temperature and time as shown in FIG.
Expanded to about 30 to 45 times the foam, the density after foaming is about 0.01
It was 5 g / cm ³ . The depression 2 was a test excavation with a cross section of 1 m x 1 m and a depth of 80 cm. A gas injection pipe 3 having a diameter of 40 mm was placed in the depression 2 where the test was excavated, and the gas injection pipe 3 was buried in a sand layer 4 formed by spraying sand with a thickness of 60 mm. In addition, the gas injection pipe 3
It was supported by an appropriate support struck into the ground of the depression 2. After the resin beads 5 having a thickness of 23 mm were sprayed on the sand layer 4, the lid 6 was attached to the upper opening of the depression 2. In this state, steam at a temperature of 100 ° C. was supplied from the boiler to the gas injection pipe 3 at a flow rate of 0.1 m ³ per minute. Since the supplied water vapor was blown into the layer of the resin beads 5 through the sand layer 4, it had a uniform flow distribution over the entire resin bead layer. After blowing water vapor for 17 minutes, the resin beads 5
Expanded from the surface of the sand layer 4 to a height of 70 cm. At this time, in order to make the surface of the resin foam dense, the mold frame 6 was slightly lowered, and the surface of the foamed resin was pressed with a pressing force 7. Next, the mold 6 was removed, and the formed resin foam was taken out of the depression 2 and cut in the vertical and horizontal directions, and the foaming state inside was observed. As a result, it was found that the foam had a substantially uniform foam structure. Further, a test piece was cut out from the foam and the compressive strength was measured. The compressive stress value when a compressive strain of 4% was applied was in the range of 1.5 to 2.0 kg / cm ² . From this, it can be seen that a ground having a strength sufficiently larger than 0.5 kg / cm ^2, which is an average tread pressure applied during vehicle running, is obtained. On the other hand, when heat and foaming were performed by directly blowing steam onto the resin beads 5 without providing the sand layer 4, the obtained resin foam had uneven foaming state and a compressive strength of 0.5 to 2.5.
large was varied and kg / cm ^2. This is considered to be due to the fact that the flow rate of the supplied water vapor fluctuates in the gas blowing direction and that the resistance of the gas passage formed between the resin beads 5 varies. Due to the unevenness of the foaming state and the variation of the compressive strength, when a moving load was repeatedly applied on the obtained resin foam in the same manner, a locally depressed portion was detected. In the above embodiment, the embankment of the depression 2 is described as an example. However, the present invention can be applied to the creation of a sloping land, the expansion of the road width, and the like by the same method. Further, a sand layer in which a gas injection pipe is buried is further provided on the formed resin foam, and heating and foaming of the resin beads are performed again on the sand layer. Embankment can also be performed on depressions, slopes with large steps, road sides, and the like.

【The invention's effect】

As described above, in the present invention, when foaming of resin beads is performed on site to construct an artificial ground, a gas for heating and foaming is sent to the resin bead layer through a fine grain layer such as sand particles. In. Therefore, the flow distribution of the heated gas to the resin bead layer becomes uniform, and the foaming reaction is performed under substantially uniform conditions. Therefore, the inside and outside of the foamed resin are in a substantially uniform foaming state, and the compressive strength is not locally reduced. In this manner, according to the present invention, an artificial ground having sufficient strength to withstand tread pressure can be easily constructed.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment in which the present invention is applied to embankment of a depression, and FIG. 2 is a graph showing a foaming state in relation to temperature and time. 1 ... Original ground, 2 ... Slope, 3 ... Gas injection pipe, 3a ...
Gas vent, 4: Sand layer, 5 ... Resin beads, 6 ... Formwork, 7 ...
Pressing force

──────────────────────────────────────────────────続 き Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) E02D 17/18 E02D 3/00 E01C 3/00

Claims (1)

(57) [Claims] 1. A fine-grained layer in which a gas injection pipe is embedded is formed on an original ground, beads made of a foamed resin are sprayed on the fine-grained layer, and a mold is formed above the beads via a space. A civil engineering method using a foamed resin, wherein a frame is arranged, and the beads are heated and foamed by a heated gas ejected from the gas injection pipe.