JP2772997B2 - Foaming method of foamable resin in civil engineering method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a method for foaming a foamable resin in a civil engineering method in which foamable resin used for forming an embankment or artificial ground, widening a road, and the like is uniformly foamed on site.

[Prior art]

BACKGROUND ART Civil engineering methods for filling a depression or making it a part of an artificial ground by utilizing the lightness of a foamed resin have been conventionally performed. In such a construction method, for example, a foamable resin is molded into a foam block having a predetermined shape at a factory, the foam block is stacked on the original ground to be embanked, and a concrete floor plate or a wall protection material is stretched on the surface layer. Finished. Further, a reinforcing material such as a reinforcing bar is arranged inside to improve the structural strength. By the way, when foams are simply stacked to form the ground, a gap easily occurs between the foam blocks. Therefore, Japanese Utility Model Application Laid-Open No. 63-81941 and Japanese Utility Model Application Laid-Open No. 63-81942 introduce the method of forming irregularities on the surface of the foam block to eliminate the deviation, and meshing the irregularities. I have. However, the method of transporting the foamed block after foaming at the factory to the site and stacking the foamed block into a predetermined shape requires troublesome transportation and handling. In other words, for example, a large block of about 2 x 1 x 0.5 m is used as this kind of block. It costs. In addition, the transportation is substantially like carrying air,
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 which has been flattened and spread on the original ground on which the work such as embankment is to be performed. Japanese Patent Application Laid-Open No. 47-19617 discloses that an unfoamed resin such as urethane, vinyl chloride, or styrene 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]

As described above, there are various restrictions on the foaming of resin beads on site, and in particular, when the foaming of the resin beads is uneven, defects such as unevenness on the surface of the resin body after foaming and generation of internal cavities are generated. Will occur. Such a defect is presumed to be caused by a change in the foaming atmosphere of the resin beads. The present invention has been made in view of such circumstances, and has as its object to provide a foaming resin foaming method in a civil engineering method capable of uniformly foaming resin beads on site.

Means for Solving the Problems The foaming method of the foamable resin in the civil engineering method of the present invention comprises:
In order to achieve the above object, foamable resin beads are scattered directly on the original ground or through a sand layer, and a steam supply pipe for supplying steam is arranged below the resin beads, and a space is provided above the resin beads via a space. In the initial stage of foaming of the resin beads, the supply amount of the steam is set to a predetermined value or more, and in the middle stage of foaming of the resin beads, the supply amount of the steam is gradually reduced. At the end of foaming of the resin beads, the supply amount of the steam is rapidly increased to a predetermined value or more at the end of foaming of the resin beads.

[Action]

In the foaming method of the foamable resin in the civil engineering method of the present invention, while taking advantage of the on-site construction by the foamable resin,
As a method of forming the ground with the necessary strength, a method was developed in which resin beads were sprayed on the original ground partitioned by the formwork and the resin beads were foamed with a heated gas to construct the ground. In other words, the foaming reaction when the styrene resin beads are heated and foamed takes, for example, a time period as shown in FIG.
Proceed according to the temperature curve. In other words, the initial stage of foaming is 30
Foaming starts partially at a temperature of about ° C, but at this time, the foaming is very slight, and the accompanying volume expansion and pressure rise are also small. In the middle stage of foaming, foaming progresses rapidly as the temperature rises, and the volume expansion and the pressure rise suddenly. Then, at the end of the foaming, the foaming reaction becomes slow again, and the volume expansion and the pressure rise become slow. Thus, since the speed of the foaming reaction varies according to time and temperature, when foaming proceeds in a free atmosphere,
A foam having a high porosity is obtained at a portion where foaming is rapidly performed, and a dense foam is obtained at a portion where foaming progresses slowly. As a result, the foam as a whole does not have a uniform structure and strength. In this regard, in the present invention, the supply amount of steam is controlled according to the progress of foaming. That is, in the initial stage of the foaming, by setting the supply amount of the steam to a predetermined value or more, the steam is surely distributed to each resin bead, so that uniform foaming is possible. Further, in the middle stage of the foaming of the resin beads, by gradually reducing the supply amount of the steam to a predetermined value or less, the progress of the foaming is slightly suppressed, so that the porosity of the foam due to rapid foaming is small. Become. Further, in the late stage of foaming, the foaming reaction is promoted by rapidly increasing the supply amount of steam to a predetermined value or more, so that the formation of a foam having an excessively dense structure is prevented. As a result, the foam as a whole can have a uniform structure and strength.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to embankment of a depression. As shown in the figure, the bottom of the depression 2 of the original ground 1 is filled with a sand layer 4 and the sand layer 4 has a steam injection pipe 3 embedded therein. Both ends of the steam blowing pipe 3 are supported by columns 5 and 6 and are maintained at a certain height from the bottom surface of the depression 2. Prop 5, 6
Is driven into the soil of the original ground 1 and acts as a pile. At least one of the columns 5, 6 is formed of a pipe, and a part of the column is opened inside the steam blowing pipe 3, and is connected to the boiler 9 via the air supply pipe 7 and the suction pump 8. . Note that the air supply pipe 7 may be connected to the steam blowing pipe 3 by a separate piping system. On the sand layer 4, foamable resin beads such as styrene resin
10 is scattered, and a mold 12 is disposed above the mold 10 via an internal space 11. The mold 12 has a hole through which the columns 5, 6 are inserted. The mold 12 can be moved up and down by appropriate means using the columns 5 and 6 as guides. Reference numeral 13 denotes an exhaust pipe penetrating the mold 12 and communicating with the internal space 11. The exhaust pipe 13 is provided with a pressure control valve 14 for adjusting the atmospheric pressure of the internal space 11 according to the progress of the foaming reaction. Next, a procedure of a foaming method using a foamable resin will be described. As the resin beads 10, a styrene resin having an average particle size of 0.9 mm was used. This resin starts a foaming reaction in relation to temperature and time as shown in FIG.
It expands to about 45 times the foam. As the depression 2, a sample having a cross section of 1m × 1m and a depth of 80cm was drilled. Then, a steam blowing pipe 3 having a diameter of 40 mm was arranged in the recess 2 which was excavated, and the steam blowing pipe 3 was buried in a sand layer 4 formed by spraying sand with a thickness of 60 mm. The depth of the struts 5 and 6 that support the steam injection pipe 3 into the ground was 40 cm. Subsequently, after the resin beads 10 are sprayed on the sand layer 4 with a thickness of 23 mm, the mold 12 is inserted into the supports 5, 6, and the distance from the surface of the sand layer 4 to the lower surface of the mold 12 (hereinafter, referred to as This is called the height of the mold 12) was set to 30 mm. In this state, steam at a temperature of 100 ° C. was supplied from the boiler 9 to the steam injection pipe 3 via the suction pump 8 and the suction pipe 7. Here, the foaming state due to the supply of steam is as follows. First, in the initial stage of foaming, the steam supply rate is 0.1 m / min.
³ or more. As a result, since the vapor is surely distributed to each resin bead, uniform foaming becomes possible. In the middle stage of foaming of the resin beads, the supply amount of steam was gradually reduced to 0.1 m ³ or less per minute. As a result, the progress of foaming is slightly suppressed, and the porosity of the foam due to rapid foaming decreases. Further, at the end of foaming, the steam supply amount was rapidly increased to 0.1 m ³ or more per minute. This promotes the foaming reaction, thereby preventing the formation of a foam having an excessively dense structure. As a result, the foam as a whole could have a uniform structure and strength. Next, the relationship between the atmospheric pressure and the supply amount of steam from the initial stage to the final stage of foaming will be described. First, in the initial stage of foaming, the atmospheric pressure was set to 1.2, and the supply rate of steam was set to 0.1 m ³ or more per minute. In the middle stage of foaming, the atmospheric pressure was maintained at 1.2, and the supply amount of steam was gradually reduced to 0.1 m ³ or less per minute. At the end of foaming, the atmospheric pressure was set to about 0.9, and the steam supply rate was set to 0.1 m ³ or more per minute. That is, in the initial stage of foaming, the foaming reaction of the resin beads 10 is accelerated by increasing the supply amount of steam, so that the atmospheric pressure is increased to suppress the progress of foaming. This makes it possible to appropriately control the porosity of the foam due to rapid foaming. In the middle stage of foaming, since the foaming of the resin beads 10 progresses rapidly, the supply amount of steam is gradually reduced according to the progress of the foaming, and the atmosphere pressure is maintained at a high level. The progress of the foaming can be appropriately controlled, thereby reducing the porosity of the foam due to rapid foaming. Furthermore, in the final stage of foaming, the foaming reaction of the resin beads 10 becomes slow, so that the foaming reaction having an excessively dense structure is promoted by rapidly increasing the supply amount of steam to promote the foaming reaction of the resin beads 10. Body formation is prevented. At the beginning of the supply of steam, when the steam from the steam blowing pipe 3 is supplied to the resin beads 10 via the sand layer 4, the resin beads 10 gradually start foaming, and the resin beads 10
The volume increased with the foaming. Then, while the mold 12 was raised at a speed of 5 cm per minute, steam was blown in for 16 minutes. In this way, after the resin beads 10 are foamed,
The mold 12 was removed, the resin foam was cut out in the vertical direction, and the cross section of the resin foam was observed. As a result, no change in the foaming state in the vertical direction was observed. Further, compressive strength of the resin foam body in the vertical direction in the range of 1.5~2.0kg / cm ^2, an average, trampling applied during vehicle travel 0.5 kg / cm
^The value was sufficiently larger than ² . Further, since the pillars 5 and 6 are provided as reinforcing materials inside the foamed resin body, most of the stepping pressure due to the traveling vehicle or the like is received by the steam injection pipe 3 and can be used as a solid ground. Was. As described above, in the present embodiment, the pressure and the amount of steam in the atmosphere are appropriately controlled in accordance with the progress of foaming of the resin beads, so that a uniform foamed resin body as a whole can be obtained. Further, in the present embodiment, since the steam injection pipe is provided as a reinforcing material, most of the stepping pressure due to the traveling vehicle or the like can be received by the steam injection pipe, so that a stronger ground can be obtained. . In this embodiment, the case where the embankment is filled in the depression has been described. However, the present invention is not limited to this example, and the present invention may be applied to the creation of an inclined land, the expansion of the road width, and the like by the same method.

【The invention's effect】

As described above, according to the foaming method of the expandable resin in the civil engineering method of the present invention, the amount of steam in the atmosphere is appropriately controlled according to the progress of foaming of the resin beads. A flexible foamed resin body can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which the present invention is applied to embankment of a depression, FIG. 2 is a view showing the relationship between the atmospheric pressure and the amount of steam to be supplied to the resin beads of FIG. FIG. 3 is a diagram showing the foaming state of the resin beads of FIG. 1 in relation to temperature and time. 1 ... original ground, 2 ... depression, 3 ... gas injection pipe, 4 ...
... Sand layer, 5,6 ... Post, 7 ... Air supply pipe, 8 ... Intake pump, 9 ... Boiler, 10 ... Bead, 12 ... Form, 13 ...
... exhaust pipe, 14 ... pressure control valve.

──────────────────────────────────────────────────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 (2)

(57) [Claims] 1. A foaming resin bead is sprayed on the original ground directly or through a sand layer, and a steam supply pipe for supplying steam is disposed below the foamed resin bead, and a mold is provided above the resin bead via a space. In the initial stage of the foaming of the resin beads, the supply amount of the steam is set to a predetermined value or more, and in the middle stage of the foaming of the resin beads, the supply amount of the steam is gradually reduced to a predetermined value or less. In the final stage of foaming of the resin beads, the supply amount of the steam is rapidly increased to a predetermined value or more. 2. In the initial stage of the foaming of the resin beads, the atmospheric pressure in the space is set to 1 atm or more,
In the middle stage of foaming of the resin beads, the supply amount of the steam is equal to or more than a predetermined value, and while maintaining the atmospheric pressure in the initial stage of the foaming, the supply amount of the steam is gradually reduced to a predetermined value or less. In the final stage of foaming, the atmospheric pressure is less than 1 atm, and the supply amount of the steam is rapidly increased to a predetermined value or more. Foaming method.