JPH036288B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of constructing a waterway by burying a tubular concrete structure underground.

[Prior Art] Generally, a pipe body such as a hume pipe is often used as such a drain pipe. If the amount of earth cover is large, the earth pressure acting on the pipe will also increase depending on the depth of the earth cover. For this reason, since the hume pipe alone does not have enough load-bearing capacity to withstand earth pressure, some kind of reinforcing measure is required.

For example, a Huyum tube with an inner diameter of 1000 mm (JIS
A5303 external pressure type 1) is buried in the soil with an overburden of 50 m,
Assume that a vertical earth pressure of 171t/ ^m2 acts. The lower half of the Huyum pipe is covered with concrete.
The load capacity of the hume pipe on a 180° concrete foundation is 12.6 t/m ² , which is only 7.3% of the acting earth pressure, so it cannot be used in this case.

Therefore, as shown in FIG. 2, it is necessary to wrap the pipe body 2 made of a humid pipe with a concrete wrapping part 4 to reinforce it and bury it.

[Problems to be solved by the invention] However, in the case of this construction method, the load distribution is as shown in Fig. 3, and the earth pressure does not act evenly on the pipe body 2, resulting in large bends in the top and bottom of the pipe body 2. generates a moment. Therefore, this point must be taken into consideration in the design.

For example, the thickness of the concrete rolling part 4 is 50
cm, the relationship between the winding thickness and shear stress when considering the bending moment is the vertical earth pressure.
It is about 0.025Kg/ ^cm2 per 1t/ ^m2 . The allowable shear stress of concrete is 2.7% of the design standard strength,
If the design standard strength is 160Kg/cm ² , the allowable shear stress is 4.3Kg/cm ² . The shear stress at a vertical earth pressure of 171 t/m ² is 171×0.0025=4.3 Kg/cm ² , which is equal to the above-mentioned allowable shear stress, so the minimum winding thickness is required to be 50 cm.

In this way, if the amount of soil covering increases, the
must be given considerable thickness.

The object of the present invention is to solve the conventional drawbacks of the above-mentioned pipe and waterway construction methods, and to provide a construction method that can sufficiently withstand earth pressure with a smaller concrete thickness.

[Means for Solving the Problems] That is, the object of the present invention is to provide a construction method for constructing a waterway by burying a concrete structure underground, the outer shape of the cross section being approximately square, and the inner shape of the concrete structure being approximately square. A hollow concrete structure 6 whose center is the intersection of diagonals of the square is used, and this structure 6 is buried underground so that one diagonal of the square is substantially vertical. This is achieved by the concrete waterway construction method.

[Operation] According to the present invention, it is assumed that the concrete structure 6 shown in FIG. 1 is buried as shown in FIG. 4. In this case, since the earth cover on top of the concrete structure 6 is large, the horizontal earth pressure p _h can be considered to be uniform over the top and bottom of the structure 6, and the self weight of the structure 6 can be ignored. shall be obtained.

In this case, the vertical load p _v is the component force p _v1 acting perpendicularly to the concrete outer surface inclined at 45°,
It can be expressed as a component force p _v2 acting along the outer surface. Of the component forces P _v1 and p _v2 , the component force p _v1 perpendicular to the outer surface is the pressure applied to the concrete structure 6. Similarly, for the horizontal earth pressure p _h , the component force acting perpendicularly to the outer surface is
p _h1 can be obtained as the pressure applied to the concrete structure 6, and the component forces of vertical earth pressure and horizontal earth pressure that act perpendicularly to the external surface are both pressures that act on the same surface in the same direction. be. In this case, the external pressure acting perpendicularly to the outer surface acts equally on the outer surface as shown in FIG. 5, and its magnitude is p=(q _v1 +q _h1 )/√2, 71% of (q _v1 + q _h1 ) will act.

Furthermore, assuming that the shaded area in Fig. 6 is a rigid body that transmits earth pressure inside it, the earth pressure will be applied to the outer periphery of the part corresponding to pipe body 2 in Fig. 2, as shown in Fig. 7. Acts evenly. Therefore, no bending moment is generated in the tube, only uniform compressive stress is generated. Therefore, when designing the waterway, there is no need to consider bending moment, and it is sufficient to consider only the compressive stress that is uniformly applied to the structure. Concrete structures inherently have the property of being particularly strong against compressive stress and relatively weak against tension, so these properties can be effectively utilized.

As shown in Figure 6, the concrete structure is
Naturally, the outer corners are also subjected to loads due to earth pressure, but in this case, this is the thickest part of the concrete member, and rather, when considering stress, the stress distribution as shown in Figure 7 is based on the thickness of the thinnest part. Just think about it.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

1 and 2 show an example of the cross-sectional shape of a concrete structure 6 used in the construction method of the present invention. The structure 6 shown in FIG. 2 is constructed by forming a concrete raised part 4 around a pipe body 2 made of a humid pipe or the like for reinforcement. Further, the structure 6 shown in FIG. 1 is an integral structure of the pipe shown in FIG. 2. In the former case, mainly only the central pipe body 2 is pre-formed in a factory as a humid pipe, etc., and the surrounding winding part 4 is formed by assembling formwork and reinforcing bars and pouring concrete on site by so-called cast-in-place casting. There are many. Moreover, in the latter case, the entire concrete structure 6 is mainly formed in advance in a factory, and the waterway is constructed by burying it underground on site.

In each case, the cross-sectional shape of each of these concrete structures 6 has an overall square outer shape and a circular inner shape centered on the intersection of diagonals of the square.

In the present invention, when constructing a concrete waterway by burying the concrete structure 6, one diagonal of the cross-sectional outline is installed substantially vertically, and the concrete structure 6 is buried in the soil.

As already mentioned, in the state shown in FIG. 3 in which the earth pressure does not act uniformly on the concrete structure 6, a large bending moment is generated above and below the pipe body 2. Therefore,
To counter this, a considerable thickness of concrete is required. In contrast, the present invention eliminates the bending moment that occurs in the portion that contacts the pipe body 2, and can absorb all external pressure with uniform compressive stress, which is extremely advantageous in terms of withstand load due to earth pressure.

Next, an example in which such a pipe body is actually constructed is shown in FIG. That is, when installing the concrete structure 6 according to the present invention, it is installed on a pedestal 10 to stabilize it. This pedestal 10
It is sufficient that it can support the concrete structure until the side surface of the pipe is backfilled, and it is not necessary to use it over the entire length of the pipe. For example, as shown in FIG. 9, pedestals 10, 10' of arbitrary length may be used. Of course, it can be used over the entire length of the pipe, but it is often more troublesome to construct.

The pedestal 10 is made of concrete, plastic,
Wooden is better. Even if the concrete structure 6 has several dimensions, the receiving part is a right-angled groove, so
All can be used in common.

During construction, the sides of the pipe are sloped at 45 degrees (one diagonal line is perpendicular to the other), making it easy to backfill and compact the soil during construction, and to obtain ground reaction force against earth pressure. Easy to construct. In addition, since the corners of the pipe are in contact with the installation ground, and the area of the ground contact area is very small, if the side compaction is insufficient, the concrete structure will sink into the ground, causing a load on the ground below the sides. The stress state already described can be easily realized by applying

[Effects of the Invention] As explained above, according to the present invention, it is possible to effectively absorb the earth pressure applied to a concrete structure, eliminate the occurrence of bending moment, and absorb all the earth pressure with uniform compressive stress. Therefore, it will be possible to downsize concrete waterways, simplify construction, and strengthen the structure.

[Brief explanation of drawings]

FIGS. 1 and 2 are longitudinal sectional front views showing examples of concrete structures used to carry out the present invention;
Fig. 3 is an explanatory diagram showing the load distribution applied to the waterway due to earth pressure in a conventional construction example, Figs. 4 to 7 are explanatory diagrams showing the load distribution of the waterway constructed according to the present invention, and Fig. 8 9 are a front view and a side view showing a specific example of construction of a waterway according to the present invention. 2... Pipe body, 4... Rolling part, 6... Concrete structure, 10, 10'... cradle.

Claims (1)

[Claims] 1. A construction method for constructing a waterway by burying a concrete structure underground, wherein the outer shape of the cross section is approximately square and the inner shape is centered at the intersection of diagonals of the square. A method of constructing a concrete waterway, which comprises using a hollow concrete structure having a substantially circular shape and burying the structure underground so that one diagonal of the square is substantially vertical. 2. A method for constructing a concrete waterway according to claim 1, wherein the concrete structure is formed by integrally molding an inner portion and an outer portion. 3. A method of constructing a concrete waterway according to claim 1, wherein the concrete structure has an inner portion and an outer portion molded separately.