KR100423497B1 - Invert in manhole - Google Patents

Abstract

An object of the present invention is to provide an invert of the manhole to minimize the head loss, and to prevent the safety accident of the operator.

Accordingly, the present invention is installed in the bottom of the manhole connecting the inlet pipe and the outlet pipe, the upper end is extended to the upper part of the inlet pipe of the manhole, the channel formed at the top of the bottom portion is connected to the inlet pipe to form a semi-circular cross section and It consists of a straight portion extending vertically on both sides of the bottom provides an invert of the manhole characterized in that it has a U-shaped cross-sectional structure.

Description

Invert in manhole}

The present invention relates to an invert installed in the manhole, and more particularly, to an invert of the manhole that can minimize energy loss.

In general, the invert of the manhole is a bottom structure of the manhole, which is installed for the purpose of preventing or preventing odor generated by sediment mixed with sewage introduced into the manhole and facilitating the flow of sewage. And a block formed with a channel having a size corresponding to the lower half of the outlet pipe.

Therefore, the inflow pipe and the outflow pipe are smoothly connected in the manhole by the invert, so that the sewage can flow smoothly, and additionally, it is possible to reduce the hydraulic energy loss due to the rapid cross-sectional reduction of the inflow pipe and the outflow pipe. do.

As shown in Figure 6, the invert 100 is made to be the same as the diameter and inclination of the outflow pipe, the height is slightly different depending on the diameter, but is usually produced at 1/2 level of the diameter. And the upper foot pad portion 120 on both sides of the waterway 110 to be inclined downward 10 to 20% toward the waterway, when the sewage more than the height of the invert 100 can flow smoothly into the waterway 110 of the invert. It is supposed to be.

However, the invert of the conventional structure has a problem that the head loss is increased when the water level in the conduit rises due to the large inflow of sewage, such as local heavy rain that occurs frequently in recent years.

In other words, the head loss that can occur in the manhole is the loss due to the change of the cross section and the friction loss due to the increase of the roughness coefficient due to the change of the inverted material. As described above, as the sewage flows above the height of the invert, The head loss is caused by the rapid expansion and abrupt reduction of.

The head loss is larger in the case of the square manhole, and in the case of the circular manhole, the change of the cross section is not abrupt.

1. If there is an invert, the invert exists in a straight line with respect to the outflow and inflow directions.

2. Even if there is no invert, if there is a step in the manhole, it is a sudden sharpening.

3. Even if there is no invert without step, in case of point loss, the connection angle is 41 to 71 degrees under the diameter of 1000mm or less, and the point loss factor is 0.9 ~ 1.2 (average 1.0). ~ 0.52, connection angle is 41 to 71 degrees, approaching the rapid loss (this is mentioned in the detailed description).

In addition, both sides of the channel of the invert serves as a foot stepping part of the worker. As described above, in the case of the conventional inverting, the stepping part is inclined downward so that an accident in which the worker slips and falls off occurs.

Therefore, the present inventors have attempted to develop an invert that can minimize head loss in spite of a sudden increase in sewage.

During the development process, various experiments were conducted and found that it is necessary to solve the following technical challenges in order to obtain an invert that can substantially minimize head loss and prevent safety accidents.

First, head loss is caused by sharpening and sharpening of the manhole cross section, so the sharpening and sharpening of the cross section should not occur even when the amount of sewage increases. In this case, the construction cost may be increased if the manhole having a size larger than the required capacity is replaced.

Second, it is necessary to install both sides of the invert canal in a horizontal state. Accordingly, when the amount of sewage increases, there is a need for a structure to prevent the overflow of sewage to the upper side of the invert.

Accordingly, the present invention has been made to meet the above requirements, and an object of the present invention is to provide an inverted manhole that can minimize head loss.

In addition, another object of the present invention is to provide an invert of the manhole that can prevent the safety accident of the operator.

1 is a cross-sectional view showing an invert according to the present invention,

2 is a cross-sectional view showing an invert according to another embodiment of the present invention;

3 is a graph showing the ratio of the flow rate ratio and the flow rate ratio according to the depth ratio of the circular conduit for determining the length of the straight portion of the invert according to the present invention,

Figure 4 shows each kind of invert used for the experiment of the present invention,

5 is a graph showing the change in head loss according to each type of invert shape shown in FIG.

6 is a cross-sectional view showing an invert according to the prior art.

Explanation of symbols on the main parts of the drawings

10: invert 20: waterway

21: semi-circular bottom portion 22: straight portion

30: foot step

In order to achieve the above object, the present invention, in the invert of the manhole, extends the height of the invert to the top of the inlet pipe, the channel formed in the invert is extended to the top of the semi-circular bottom and semi-circular bottom connected to the inlet pipe It has a structure having a straight portion.

Further, the invert of the present invention has a structure in which the upper ends of both sides of the waterway are horizontal.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view showing an invert according to the present invention, Figure 2 is a cross-sectional view showing an invert according to another embodiment of the present invention.

According to the drawings, the invert 10 of the present invention, the upper end is extended to the upper portion of the inlet pipe of the manhole, the upper end is formed with a channel 20 for connecting the outlet pipe and the outlet tube of the manhole, the channel 20 ) Has a semi-circular cross-section consisting of a bottom portion 21 connected to the inlet pipe and a straight portion 22 extending vertically from both sides of the bottom portion 21 to have a U-shaped cross-sectional structure as a whole.

Accordingly, the height of the inverted waterway 20 in which the sewage flows substantially increases as much as the length of the straight portion 22, thereby increasing the depth from the top of the inverted to the bottom of the waterway 20.

This structure serves to prevent the sudden expansion and contraction of the cross-sectional area of the manhole by minimizing the head loss, so that the straight portion 22 of the waterway 20 flows in large quantities when the large amount of sewage inflow.

Here, the position of the upper end of the invert is preferably to be between 0.8 ~ 1.0D when the diameter of the inlet pipe D. That is, the semi-circular bottom portion 21, which is the bottom of the channel 20, has a height to the top of 0.5D, and the straight portion 22 forms the remaining height of 0.8 to 1.0D.

In addition, the invert of the present invention has a structure in which the stepping portion 30, which is the upper end on both sides of the channel 20, is horizontal. Accordingly, the worker can prevent a safety accident that slips on the stepping portion (30).

Straight part length determination

3 is a graph showing the relationship between the depth ratio and the flow rate, flow rate of the circular conduit for determining the length of the upper straight portion of the invert.

In order to minimize head loss, it is advantageous to connect the invert 10 to the well, but the access to the waterway bottom 21 during maintenance is reduced to the large diameter landscape, so it is necessary to determine the appropriate length.

According to the above graph, the maximum flow velocity is shown near the depth of 81% due to the characteristics of the circular conduit, and since the flow rate is also close to the total flow rate, when the height of the semi-circular bottom portion 21 is 0.5D, the length of the straight portion 22 is 0.3 to 0.5. It can be seen that it is preferable to apply D.

More preferably, according to the commentary on the sewer standard (December 1990, Ministry of Construction and Transportation), the maximum depth of the invert 10 is not more than 50 cm, which is considered maintenance, and in consideration of these issues, the diameter of the inflow pipe D Is 500 mm or less, the length of the straight portion is 0.5D so that the invert top position is 1.0D, so that the channel 20 of the invert is made the same depth as the diameter, and when the diameter of the inflow pipe is 600 mm or more, the length of the straight portion is By setting 0.3D as the position of the top of the invert to be at 0.8D, the invert channel 20 is manufactured to a depth of 80% of the diameter (see FIGS. 1 and 2).

Experimental Example

The inverted shape in the manhole can be classified into five cases as shown in FIG. 4, and the manhole of the conventional merged sewer pipe is mostly included in two forms without the invert 10.

As shown in FIG. 4, various types of inverts have been tested. As for the frictional loss caused by the change of roughness coefficient according to the change of the inverted material, only the change of the cross section is given to the same conditions for all the inverts used in the experiment. It was applied to head loss in manholes.

Jane in accordance with the connection between sewer pipe and manhole Connector inner diameter (mm) Manhole Inner Diameter (mm) Cross sectional area in conduit / Cross sectional area in manhole Connection angle (°) Invert (semicircular) Invert (0.8D) Invert (1.0D) Invert nothing (A) Inverted radish (B) 300 900 0.41 0.61 0.88 0.17 0.26 70.5 400 900 0.52 0.69 0.88 0.25 0.35 63.6 500 900 0.61 0.75 0.88 0.34 0.44 56.3 600 900 0.69 0.79 0.88 0.42 0.52 48.2 700 1200 0.63 0.76 0.88 0.38 0.46 54.3 800 1200 0.69 0.79 0.88 0.44 0.52 48.2 900 1200 0.74 0.82 0.88 0.50 0.59 41.4 1000 1500 0.69 0.79 0.88 0.46 0.52 48.2 1100 1500 0.73 0.81 0.88 0.51 0.58 42.8 1200 1500 0.77 0.83 0.88 0.56 0.63 36.9 1350 1800 0.74 0.82 0.88 0.53 0.59 41.4 1500 1800 0.79 0.84 0.88 0.59 0.65 33.6 1650 2100 0.76 0.83 0.88 0.57 0.62 40.4 1800 2100 0.80 0.85 0.88 0.62 0.67 31.0

As shown in Table 1, in the case of the square manhole, head loss due to rapid expansion and rapid axle was applied. Circular manhole can be regarded as loss due to point accumulation and point axle, but the water loss due to rapid expansion and axle was applied for the following reasons.

First, when there is an invert, since the invert exists in a straight line with respect to the outflow and inflow directions, the change of the cross section is similar to the rapid and rapid axis. Second, even if there is no invert, if there is a step in the manhole, it corresponds to rapid and rapid accumulation. Third, even if there is no invert without step, in case of point loss, the connection angle is 41 ~ 71 degrees under the diameter of 1000mm and the point loss factor is 0.9 ~ 1.2 (average 1.0). ~ 0.52, connection angle 41 ~ 71 degrees, approaching the sudden loss.

5 is a graph showing changes in head loss due to rapid expansion and rapid accumulation in the manhole according to the shape and depth ratio of each invert used in the experiment.

Conventionally, the hydraulic calculation of sewage pipes only considers friction loss at a certain point, and in consideration of the loss that may occur in the manhole, a free fall of about 3 cm is recommended. However, as shown in the graph, the head of the manhole without invert is The loss is large enough to affect the repair of the entire conduit.

And, when there is a semi-circular invert than the manhole without the invert, the head loss can be reduced to less than half, and the U-shaped invert according to the present invention can reduce the head loss to less than half as compared to the semi-circular invert.

In addition, sewage pipes have a certain ratio of margin, so there will be no problem with the existing semi-circular invert, but in the case of excellent pipes that do not consider the margin, problems may occur if the rainfall flows more than the planned excellent amount. In case of local rainfall, the water level in the conduit rises more than 80%, and it can be seen that the change of head loss according to the shape of the invert is large enough to provide the cause of urban flooding.

It can be seen that the present invention provides a very innovative invert that can minimize head loss as described above. While exemplary embodiments of the present invention have been shown and described, various modifications and other embodiments may be made by those skilled in the art. Such modifications and other embodiments are all considered and included in the appended claims, without departing from the true spirit and scope of the invention.

According to the invert of the manhole according to the present invention as described above, the head loss due to the cross-sectional change can be minimized to near zero even in the hydraulic loss due to the rapid expansion of the cross-section of the manhole, rapid accumulation and increase of the water level during large inflow of sewage .

In addition, by managing the depth of the sewage up to 80% or more can be installed horizontally on the top of the invert has the effect of preventing the safety accident of the worker.

In addition, it can be applied to rainwater as well as sewage can prevent the occurrence of urban flooding during local heavy rain.

Claims (5)

In the invert is installed on the bottom of the manhole connecting the inlet and outlet, The upper end extends to the upper part of the inlet pipe of the manhole, and the channel formed at the upper end has a U-shaped cross-section structure formed of a bottom part connected to the inlet pipe by forming a semi-circular cross section, and a straight part extending vertically from both sides of the bottom part. Invert of the manhole. 2. The invert of the manhole of claim 1, wherein the invert is horizontal with both upper and lower foot portions of the channel. The invert of the manhole according to claim 1 or 2, wherein the invert has a height of a semi-circular bottom of 0.5D and a length of a straight portion of 0.3-0.5D when the diameter of the inlet pipe is D. 4. The inverter of a manhole according to claim 3, wherein when the diameter D of the inlet pipe is 500 mm or less, the length of the straight portion is 0.5D. 4. The inverter of a manhole according to claim 3, wherein the length of the straight portion is 0.3D when the diameter of the inlet pipe is 600 mm or more.