JP2007146485A - Underground case - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground case for a handhole, a manhole, or the like lightweight with excellent working efficiency and transport efficiency and high strength. <P>SOLUTION: The handhole 1 consists of an upper member 2 and a lower member 3 formed of porous moldings containing glass chops in a dispersed state in moldings formed of cement, water and a foaming agent kneaded, molded into predetermined shape, cured and solidified, and the specific gravity of porous molding body including reinforcing bars 4, 5 is 1.0 ton/m<SP>3</SP>-2.0 ton/m<SP>3</SP>. Strength becomes high when L-shaped angles 27, 38 are embedded in four corners of the case in a state closely adhered to the reinforcing bars 4, 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an underground box such as a hand hole or a manhole used when, for example, an electric cable, a communication cable or the like is wired underground.

  Underground boxes such as handholes and manholes are required to have high strength to withstand a large static load of 20 tons, 25 tons or even 40 tons in order to withstand the load of passing vehicles, etc. Raru. For this reason, conventionally, those made of reinforced concrete are generally used as these underground boxes. A synthetic resin hand hole has also been proposed. Furthermore, for the purpose of improving the transportability and workability of the handhole, a handhole shell that can be divided into a top plate portion, a side wall portion, and a bottom portion is manufactured from a thermoplastic synthetic resin, and the top plate portion, the side wall portion, and Each of the bottom parts is made into a hollow double structure for weight reduction, assembled on site, and fitted with a socket block body in which a tube is embedded in the hole of the wall part, and then the hollow double wall structure of the handhole shell body A hand hole has been proposed in which fresh concrete is poured into an internal space and hardened and solidified (see Patent Document 1). In addition, cement, pozzolanic fine powder, aggregate particles with a particle size of 2 mm or less, water, and water reduction aiming to improve the workability by reducing the cross-sectional thickness and to provide a durable hand hole There has also been proposed a handhole using an ultra-high-strength concrete-based cured body composed of a cured body of a compound containing an agent and further metal fibers (see Patent Document 2).

However, for reinforced concrete, the weight per unit is as heavy as 500kg or more even with hand holes with an effective dimension of about 600x600x600mm, so in the case of precast products (secondary products), workability, truck There is a difficulty in the transportation efficiency by etc. On the other hand, those made of synthetic resin are lightweight and excellent in workability and transport efficiency, but tend to have insufficient strength and cannot be installed in places where a large load resistance such as 25 tons or 40 tons is required. In addition, since it is too light, there is a problem of floating due to spring water, etc., and there is a case where a foundation or the like is separately required for preventing floating, and there is a problem in terms of workability and construction cost. In addition, the synthetic resin hollow double structure is lightweight and has good transportation efficiency, but it requires on-site assembly, as well as pouring and curing of ready-mixed concrete. May lead to increased costs. Furthermore, hand holes using a super high-strength concrete-based hardened body can be reduced in weight even if the member dimensions can be reduced to some extent, but in order to achieve high strength, it is necessary to add metal fibers etc. Cost is high.
JP-A-6-173285 JP 2001-218349 A

  In view of the above-described conventional problems, the present invention is intended to provide a light and high strength underground box such as a handhole or a manhole.

In order to achieve the above object, the underground box of the present invention is formed by kneading cement, water and a foaming agent, forming into a predetermined shape and curing and solidifying the glass chop in a molded body. And a reinforcing bar is embedded, and a specific gravity including the reinforcing bar is 1.0 ton / m ³ or more and 2.0 ton / m ³ or less. . The glass chop is preferably contained in an amount of 3 to 15% by volume with respect to the kneaded mixture of cement and water.

  The reinforcing reinforcing bar preferably has a long angle member fixed in the height direction of the box, and the angle member is preferably embedded in the corner of the box. Further, it is preferable that the angle member has a substantially L-shaped cross section.

  Moreover, the underground box of this invention may contain the sand, gravel, or another aggregate in cement.

  The underground box may be integrally molded as a whole, or may be composed of a plurality of molded bodies divided in the height direction.

  The underground box of the present invention is particularly preferably used as a hand hole.

Since the underground box according to the present invention is composed of a porous molded body having a large number of closed cells formed by a foaming agent, the conventional reinforced concrete underground box has a specific gravity of only 2.3 t / m. ³ , specific gravity including reinforcing steel bars is about 2.4 t / m ³ , and the weight per handhole with an effective size of 600 x 600 x 600 mm exceeds 500 kg. 1.0 to 2.0 t / m ³ or less, a handhole of the above dimensions can reduce the weight per unit to 250 to 300 kg, has excellent workability, and transport efficiency by trucks, etc. In addition, precast products (secondary products) simplify on-site construction, and the curing period at the construction site is unnecessary, so the construction period can be shortened and construction costs can be reduced. Moreover, since the specific gravity is 1.0 or more, there is no problem of floating due to spring water or the like. And although it is lightweight, since the said porous molded body which comprises a box has the structure reinforced with the glass chop and reinforcing steel which contain in a dispersed state, at least static load 20 tons or more Furthermore, it can be provided with high strength that can withstand 40 tons.

  The underground box of the present invention contains 3 to 15% by volume of a glass chop with respect to a kneaded mixture of cement and water, so that even a lightweight porous body having a small specific gravity can be used as a handhole or a manhole. The required sufficient strength can be ensured.

  Furthermore, when an angle material that is long in the height direction of the box is fixed to the reinforcing steel bar, it can be made a stronger underground box, especially when the angle material is embedded in the corner of the box, knocking out to the side wall. In the case of an underground box where there is a thin wall part with a recess called, and the strength of the side wall tends to be insufficient, placing the angle material at the corner away from the knockout part, high strength Can be granted. Further, when an angle material having a substantially L-shaped cross section is used, the cement milk around the molding is good, and the cement solidified product and the angle material are in good contact with each other, resulting in high strength.

  Moreover, the underground box of the present invention can be made stronger by using mortar containing sand, concrete containing gravel, or by appropriately blending other aggregates.

  The underground box of the present invention can be used as a handhole or manhole used for underground wiring of electric cables, communication cables, etc., and various other underground structures (rooms), and particularly preferably used as a handhole. It is done.

  FIG. 1 is a perspective view showing a hand hole 1 composed of an upper member 2 and a lower member 3 with a part thereof broken, showing an embodiment of the underground box of the present invention. FIG. 2 is a plan sectional view of the upper member 2, and FIG. 2B is a plan sectional view of the lower member 3. The handhole 1 is formed by fitting the ridges 31 formed on the upper opening edge of the lower member 3 and the ridges 21 formed on the lower opening edge of the upper member 2, and bonding the bonding surface with an epoxy-based adhesive, Further, if necessary, an RC member (not shown) is placed and fixed on the upper member 2, and the opening that appears on the ground surface is buried in the ground in a state that it is closed with a metal lid so that it can be opened and closed.

As shown in FIGS. 4A and 4B, the upper member 2 and the lower member 3, respectively, are cement milk in which cement, water, and a foaming agent are kneaded and glass chops are mixed and dispersed therein. It is made of cement solidified material that has been molded and cured in a predetermined shape with molding dies 6 and 7 in which reinforcing reinforcing bars 4 and 5 are installed. The molded body contains glass chops in a dispersed state and includes reinforcing reinforcing bars. The porous molded body is embedded and has a specific gravity including the reinforcing reinforcing bar of 1.0 ton / m ³ or more and 2.0 ton / m ³ or less.

  The upper member 2 shown in the figure is opened downward, the side wall 22 is formed thicker in the upper part than in the lower part, and the circular opening 20 is formed in the upper wall 23. Reinforcing bars 4 embedded in the upper member 2 have upper and lower horizontal bars 24 and 25 connected in a cross-girder shape connected by vertical bars 25, and at the four corners are long in the height direction and L-shaped in cross section. An angle member 27 is connected and fixed to the upper and lower horizontal stripes 24 and 25. Further, the upper horizontal stripes 24 are arranged inside and outside, and the short stripes 28 are connected and fixed between them, and the adjacent horizontal stripes 24 across the corners are provided with openings 23 formed in the upper wall 23. It is connected and fixed by an oblique line 29 so as to surround it.

  On the other hand, the lower member 3 in the illustrated example opens upward, and on each outer surface side of the four side walls 32 is provided with a recess 33 called a knockout with a thin wall thickness for inserting a cable or the like. Drilling is easy, and a circular recess 35 for forming a drain hole is provided on the upper surface of the bottom wall 34 to reduce the wall thickness. The reinforcing reinforcing bars 5 of the lower member 3 have a plurality of horizontal bars 36 spaced in the vertical direction connected in an inverted U shape with a plurality of continuous vertical bars 37 extending from the side wall 32 to the bottom wall 34, and a knockout 33. At the four corners of the box, which is located away from the box, angle members 38 that are long in the height direction and have an L-shaped cross-section are connected and fixed to a plurality of horizontal bars 36 arranged vertically. The horizontal stripes 36 and the vertical stripes 37 are cut at portions corresponding to the knockout 33 of the side wall 32 and the recess 35 for the drain hole of the bottom wall 34.

  In addition, the shape and structure of the upper member 2 and the lower member 3, and the shape and structure of the reinforcing reinforcing bars 4 and 5 embedded in them are not limited to those described above, and depend on the application and required strength. It can be designed as appropriate. Further, the angle members 27 and 38 are not necessarily provided at the four corners, and may be provided at different positions. Further, depending on the size and required strength of the handhole, the angle members 27 and 38 may be provided as shown in FIG. Only the reinforcing bars may be used without using any material. In the handhole 1A shown in FIG. 3, the same structural parts as those of the handhole 1 shown in FIGS.

  The hand holes 1 and 1A shown in the figure are both composed of two members, an upper member 2 and 2A, and a lower member 3 and 3A. The upper member 2 and 2A and the lower member are interposed between the two members. It is also possible to arrange a cylindrical intermediate member connectable to each of 3, 3A and use it as a hand hole having a different height. As an intermediate member in this case, like the upper member 2, 2A and the lower member 3, 3A, the intermediate member may be made of a cement solidified product made of a porous molded body containing a glass chop and embedded with reinforcing bars. However, it may be made of ordinary reinforced concrete. Furthermore, according to a use, required intensity | strength, etc., it is good also considering either one of the up-and-down members 2, 3 or an intermediate member made from normal reinforced concrete.

  As shown in FIG. 4, the handhole 1 is made of cement milk obtained by mixing and kneading cement, a foaming agent, a glass chop, and water, as shown in FIG. Cement milk containing foaming agent is hardened by hydration reaction between cement and water, and is made of lightweight porous molded body with many closed cells. Obtained as a solidified product. The upper member molding die 6 and the lower member molding die 7 shown in FIG. 4 are provided with bottom frames 61 and 71 and side frames 62 and 72 that are continuously connected to the four sides of the bottom frames 61 and 71 and surrounded by the side frames 62 and 72. On the upper surfaces of the bottom frames 61 and 71 of the inner space, there are provided inner frames 63 and 73 for forming the inner spaces of the upper member 2 and the lower member 3, and further, an inner frame of the upper member molding die 6. On 63, a separation mold 64 for forming the opening 20 of the upper member 2 is arranged. After the cement milk is injected, cured and solidified, as shown by phantom lines in the figure, each mold After the side frames 61 and 71 are opened and the separation mold 64 is removed from the upper member 2, the upper member 2 and the lower member 3, which are molded products, are taken out from the respective molding dies 6 and 7. In this molding die, the lower member 3 is molded in a posture inverted up and down from the use state. Needless to say, the mold for molding the underground box of the present invention, such as a hand hole, is not limited to that shown in FIG. 4, and molds having various structures can be used.

  The cement used in the present invention is not particularly limited, and various cements such as ordinary Portland cement, early-strength Portland cement, and ultra-early-strength Portland cement can be used. From the viewpoint of productivity and strength, it is preferable to use early-strength Portland cement. Further, the foaming agent is not particularly limited, and various known foaming agents such as a protein system, a surfactant system, and a resin system can be used. Furthermore, although the fiber length of the glass chop which is a short glass fiber is not specifically limited, the thing of the range of 3-20 mm is preferable, More preferably, it is 5-15 mm. If the fiber length is less than 3 mm, the glass chop tends to have insufficient reinforcing effect, and if it exceeds 20 mm, the dispersibility tends to decrease. It is also preferable to use a glass chop sprayed or impregnated with a binder such as epoxy or styrene in order to improve the adhesiveness with the cement solidified material and achieve higher strength.

The blending ratio of cement and water is preferably a weight ratio in the range of cement: water = 1: 1 to 1: 0.2. If the amount of water is too much, the strength tends to decrease. If the amount of water is too small, the fluidity of the cement milk tends to be lowered during molding, thereby hindering the moldability. Moreover, it is preferable that the addition amount of glass chop shall be 3-15 volume% with respect to the kneaded material (cement milk) of cement and water. When the glass chop is less than 3% by volume, the strength of the resulting panel tends to be insufficient. On the other hand, when the glass chop exceeds 15% by volume, the dispersibility with respect to cement milk is deteriorated and the strength of the molded product tends to be non-uniform. Furthermore, the amount of the foaming agent added is not particularly limited, but it is usually in the range of 0.5 to 10% by weight with respect to the cement, and the specific gravity of the resulting molded product (ground box) is for reinforcement. What is necessary is just to adjust suitably so that it may become the target value of 1.0-2.0 t / m < ³ > including a reinforcing bar. The specific gravity of the molded product (ground box) is more preferably in the range of 1.1 to 1.6 t / m ³ .

  In the underground box of the present invention, the cement milk can be made into mortar by adding sand as an aggregate, and can also be made into concrete by adding gravel, and further requires other aggregates, known cement additives, etc. It can be added as appropriate.

As shown in FIGS. 1A and 1B, reinforcing bars 4 and 5 having L-angle members fixed in the height direction at four corners are installed in the molds 6 and 7 as shown in FIGS. Then, cement milk mixed and kneaded with cement, water, foaming agent and glass chop was poured into the mold, cured for 14 days to solidify, and the upper member 2 and the lower member 3 of the handhole 1 were manufactured. Effective size 600 × 600 × 600 mm, height 760 mm, outer dimension 870 × 870 mm of upper member 2, opening 20 of upper wall 23, obtained by bonding upper member 2 and lower member 3 with an epoxy-based adhesive. The hand hole 1 having an inner diameter of 600 mmφ, a side wall thickness of 60 mm (size of the knockout portion of the side wall: 400 × 200 mm), and a bottom wall thickness of 80 mm (size of the recess for the drain hole on the bottom wall: 25 mmφ) has a total weight of At 279 kg, the specific gravity including reinforcing steel bars and angle members was 1.3 t / m ³ , and the results of the strength test were also good.

As shown in FIGS. 3A and 3B, reinforcing reinforcing bars 4A and 5A not provided with L-angle members at the four corners are installed in a mold as shown in FIGS. Cement milk was injected, cured for 14 days, and solidified to produce an upper member 2A and a lower member 3A of the handhole 1A. The upper member 2A and the lower member 3A were bonded with an epoxy adhesive to obtain a hand hole 1A having the same dimensions as in Example 1. This hand hole 1A had a total weight of 279 kg, a specific gravity including reinforcing bars and angle members of 1.3 t / m ³ , and the result of the strength test was also good.

(Comparative example)
Normal ready-mixed concrete is poured into a mold having reinforcing reinforcing bars shown in FIG. 3 in the same manner as in Example 2 and cured for 14 days to produce upper and lower members of the handhole. Adhesives were used to obtain reinforced concrete handholes having the same dimensions as in Example 1 and Example 2. The obtained hand hole made of reinforced concrete had a total weight of 540 kg, and the specific gravity including the reinforcing steel bars was 2.4 t / m ³ .

It is the perspective view which fractured | ruptured a part which shows one Embodiment of the underground box of this invention. (A) is a plane sectional view of an upper member, and (b) is a plane sectional view of a lower member. It is the perspective view which fractured | ruptured a part which shows other embodiment of the underground box of this invention. (A) is a simplified longitudinal cross-sectional view which shows an example of an upper member shaping | molding die, (b) is a simplified longitudinal cross-sectional view which shows an example of a lower member shaping | molding die.

Explanation of symbols

1, 1A Hand hole 2, 2A Upper member 3, 3A Lower member 4, 4A Reinforcing bar for upper member 5, 5A Reinforcing bar for lower member 6 Mold for upper member 7 Mold for lower member 20 Opening, 21 Convex Strip, 22 side walls, 23 upper wall, 24 transverse stripes, 25 transverse stripes, 26 longitudinal stripes, 27 angle material, 28 short stripes, 29 oblique stripes,
31 ridges, 32 side walls, 33 recesses (knock-out), 34 bottom walls, 35 recesses, 36 transverse stripes, 37 longitudinal stripes, 38 angle members 61 bottom frame, 62 side frames, 63 middle frame, 64 separate type 71 bottom frame , 72 Side frame, 73 Middle frame

Claims (8)

Cement, water, and a foaming agent are kneaded, molded into a predetermined shape and cured and solidified, glass chops are dispersed in the molded body, and reinforcing reinforcing bars are embedded in the reinforcing reinforcing bars. An underground box comprising a porous molded body having a specific gravity including 1.0 ton / m ³ or more and 2.0 ton / m ³ or less.   The underground box of Claim 1 which contains 3-15 volume% of glass chops with respect to the kneaded material of cement and water.   The underground box according to claim 1 or 2, wherein an angle member long in the height direction of the box is fixedly embedded in a reinforcing steel bar.   The underground box according to claim 3, wherein an angle material is embedded in a corner of the box.   The underground box according to claim 4, wherein the angle member has a substantially L-shaped cross section.   The underground box according to any one of claims 1 to 5, comprising sand, gravel or other aggregates.   The underground box according to any one of claims 1 to 6, comprising a plurality of molded bodies divided in a height direction. The underground box according to any one of claims 1 to 7, which is used as a hand hole.

Images