JP2008163622A - Inverted siphon structure of sewer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent impurities from being deposited even when the flow-down force of a sewage is weak. <P>SOLUTION: An upstream side sewer 2, a vent pipe 1, and a downstream side sewer 3 are made to communicate with each other detachably in an enclosed state through an upstream side conduit 6 and a downstream side conduit 7 in an upstream side manhole 4 and a downstream side manhole 5. A pipe with variable cross section increasing or decreasing according to the increase or decrease of the inflow amount of the sewage is used for the upstream side conduit 6. Consequently, the velocity energy of the sewage flowing down in the upstream side sewage 2 can be effectively used, and even if the flow amount of the sewage is less, the potential energy is not reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an underground structure of a sewer pipe that passes under an obstacle such as a river or an underground passage, and particularly relates to an underground structure of a sewer pipe communicating in a sealed state from the outside.

  The sewage pipe that separates domestic household wastewater, industrial facility wastewater, and the like is laid at a slight downward slope of 3/1000 or less, and the sewage flows downstream. However, if there are obstacles such as rivers and underpasses in the middle of the flow path, means for crossing these obstacles is required.

  As means for crossing the obstacle, conventionally, means for pumping sewage mainly with a pump or the like and crossing the obstacle is used. However, this means requires a pumping device such as an electric motor, a crossing path such as a water pipe bridge, a control machine, and the like, and there is a problem that the construction cost and the maintenance and inspection cost are high.

  Therefore, as another means for traversing the obstacle, an underlay structure that has penetrated under the obstacle has been used. Here, a typical overturn structure according to the prior art is shown in FIG. That is, an upstream manhole 404 is provided on the upstream side of the sewage pipe across the river, and a downstream manhole 405 is provided on the downstream side of the sewage pipe. The bottom portion of the upstream manhole 404 and the bottom portion of the downstream manhole 405 are communicated with each other by an overpass tube 401. The upstream sewage pipe 402 communicates with the upper part of the upstream manhole 404, and the downstream sewage pipe 403 communicates with the upper part of the downstream manhole 405.

Note that the difference ΔH between the bottom surface of the upstream sewage pipe 402 and the position communicating with the upstream manhole 404 and the bottom surface of the downstream sewage pipe 403 and the position communicating with the downstream manhole 405 is a so-called sag. The head is set to the head. Here, the head drop: H is calculated by, for example, the following formula shown in “Sewerage Facility Planning and Design Guidelines and Explanations, Japan Sewerage Association”.
^{H = i · L + β ·} (V 2 / 2g) + α
here,
H: Overhead loss head (m)
i: Hydrodynamic gradient with respect to the flow velocity in the overpass
L: Length of the overpass pipe (m)
V: Flow velocity in the overpass pipe (m / s)
g: Gravitational acceleration (9.8 m / s ² )
α: margin width (30-50mm)
β: 1.5 is the standard.
In addition, the diameter of the underground pipe is reduced, and the flow rate is increased by 20 to 30% from the flow rate in the sewer pipe.

  However, the above described overturn structure has the following problems. That is, sewage, which is domestic wastewater, is mixed with floating contaminants such as oil and sedimentary contaminants such as earth and sand, and these gradually accumulate in the upstream manhole 404 and flow into the overpass 401. If the amount of sewage is reduced and left as it is, there is a risk of blocking the underground pipe. Specifically, as shown in FIG. 10, the water surface height in the upstream manhole 404 is lowered by an approximately heading drop: ΔH from the lower surface of the outlet where the upstream sewage pipe 402 opens into the manhole. It becomes the position. Therefore, the floating contaminant S1 having a low specific gravity floats on the water surface in the upstream manhole 404, while the sedimentary contaminant S2 having a high specific gravity accumulates at the bottom of the upstream manhole. And these floating impurities S1 and sedimentary impurities S2 become enlarged with time and cause the overhang tube 401 to be blocked.

  For this reason, the applicants of the present application have created and implemented an improved underlay structure in which there is no room for accumulation of floating impurities S1 and sedimentary impurities S2 in the upstream manhole 404. ing. That is, as shown in FIG. 11, this improved overturning structure has a UU in which the upstream sewage pipe 502 is communicated with the bottom surface of the upstream manhole 504 and inflowing sewage is provided on the bottom surface of the upstream manhole. It flows into the flow guide groove having a letter-shaped cross section, and the underlay pipe 501 is communicated with the outlet of the flow guide groove. Then, an overhead drop of ΔH is made between the upstream side sewer pipe 502 and the downstream side sewer pipe 503. The underlay pipe 501 is a vent pipe, and is directed downward from the upstream manhole 504 to the downward flow portion 511, the horizontal flow portion 512 crossing the bottom of the river, and the downstream manhole 503. It is comprised from the upward flow part 513 which inclines to.

  Therefore, when the amount of sewage from the upstream sewage pipe 502 is large, even if floating specific substances S1 and sedimentary contaminants S2 having a low specific gravity flow into the upstream manhole 504, these contaminants are Since there is little room to accumulate in the manhole on the upstream side, it tends to flow out to the downward flow portion 511 of the overhang pipe 501 as it is.

In addition, there have been proposed means such as devising the slope of the overpass pipe and the diameter of the upstream manhole, or providing a pump in the downstream manhole to pump up sewage as an auxiliary (see Patent Document 1). . Alternatively, there is a means to reinforce the sewage flow force when the amount of sewage is reduced by providing a water storage part in the upstream sewage channel across the river, etc. It has been proposed (see Patent Document 2).
JP-A-2004-52512 (page 2-5, FIGS. 1 and 2) Japanese Patent Laying-Open No. 2005-126941 (page 2-13, FIG. 1)

  However, in this improved overslipping structure, as shown in FIG. 12, the floating contaminant S3 having a low specific gravity floats and accumulates on the water surface in the downward flow part 511 of the overturning pipe 501, and at the bottom, It has been found that there is a further improvement point that sedimentary impurities S4 having a high specific gravity are deposited. In other words, when the sewage flow rate is small, the sewage flow force decreases and the impurities cannot be sufficiently washed away, and these impurities tend to accumulate in the overpass pipe 501.

  Further, when the sewage flow rate is low, the means of the above-mentioned “Patent Document 1” prevents floating accumulation of floating impurities and sedimentation of sedimentary impurities, as in the above-described improved underlay structure. It is difficult to use the pump, which requires installation costs and power costs. Furthermore, the means of the above-mentioned “Patent Document 2” requires the construction of a water storage part and a mechanism for opening and closing the water storage part intermittently.

  Therefore, an object of the present invention is to increase the sewage flow force by effectively using the velocity energy and potential energy of the sewage itself, and to prevent the accumulation of contaminants even when the sewage flow rate is small. It is to propose a crossover structure.

  In order to solve the above-mentioned problems, the features of the underground structure of the sewer pipe according to the present invention are that an upstream sewage pipe and a downstream sewage pipe located between obstacles such as rivers and underground passages, and a dive under this obstacle. A vent pipe that exits and an upstream manhole located at the inlet of the vent pipe are provided. The upstream sewage pipe communicates with the inlet of the vent pipe in a sealed state from the outside through an inclined upstream water conduit, and the outlet of the vent pipe communicates with the downstream sewage pipe. The upstream water conduit is detachable from the upstream sewage pipe and the inlet of the vent pipe in the upstream manhole. The vent pipe and the downstream sewage pipe may be communicated with each other in a sealed state from the outside.

  That is, in the conventional underground structure of the sewer pipe, as shown in FIGS. 9 to 12, both the upstream manholes 404 and 504 and the downstream manholes 405 and 505 are open to atmospheric pressure. Therefore, the water surface position in the upstream manhole 404 or in the downward flow portion 511 of the vent pipe 501 is substantially the height position of the water surface in the downstream sewer pipes 403 and 503. Then, when the sewage flows from the upstream sewage pipes 402 and 502 into the downstream manhole 404 or the downflow part 511 of the vent pipe 501, the water level in the upstream manhole or the downflow part rises slightly, Due to a slight difference in water level, the sewage flows downstream via the overpass pipe 401 and the vent pipe 501.

  That is, in such a conventional structure of the open air type, the velocity energy of sewage flowing at a certain speed in the upstream sewage pipes 402 and 502 is blocked by the manholes 404 and 504 on the upstream side of the open air, It is not supplied into the overpass tube 401 or the vent tube 501. Also, since the water level in the downstream manhole 404 or the downflow portion 511 of the vent pipe 501 is almost the height of the water surface in the downstream sewer pipes 403 and 503, an overhead drop of ΔH is effective. Not available for

  Therefore, as in the present invention, the upstream sewage pipe and the overburden pipe are communicated in an airtight state from the outside via the inclined upstream water conduit without opening to the atmosphere in the upstream manholes 404 and 504. Then, the velocity energy of the sewage flowing through the upstream side sewage pipes 402 and 502 is supplied as it is into the overpass pipe 401 and the vent pipe 501 and, as will be described later, in these upstream side sewage pipes and the downstream side sewage pipes. It is possible to effectively use the overhead drop: ΔH within 403 and 503 as potential energy. Therefore, by adopting the closed type overturn structure of the present invention, by effectively utilizing both the sewage velocity energy and the potential energy, the sewage flow force is increased, thereby depositing impurities. Can be prevented.

  Here, the “vent pipe” is an underground pipe that connects the upstream sewage pipe and the downstream sewage pipe, and includes a descending downward flow portion, a substantially horizontal horizontal flow portion, and an ascending upward flow. This means a substantially U-shaped sewer pipe composed of a portion. When the bent pipe is bent in the horizontal direction so as to bypass the bridge girder or the like, it is bent with a curvature as gentle as possible in the horizontal flow portion so that it is difficult for impurities to accumulate. The “upstream manhole” means a manhole located at a communication portion between the upstream sewage pipe and the vent pipe, and the shape thereof is not limited.

  In addition, “inclined upstream water conduit” means a pipe member that obliquely connects the upstream sewage pipe at the high position and the inlet of the vent pipe at the low position. There is no limitation on the means for connection. For example, the case where a stainless steel material, a synthetic resin, or the like that hardly rusts is connected to the inlet of the upstream sewage pipe and the vent pipe by a clamp, a flange, or the like. In other words, by providing an upstream water conduit that removably connects the upstream sewage pipe and the vent pipe in a sealed state from the outside, maintenance and inspection such as cleaning and repair of the vent pipe is further facilitated.

  The bottom position of the outlet of the upstream conduit is substantially the same as the bottom position of the communicating portion between the outlet of the vent pipe and the downstream sewage pipe. The inlet position and outlet of the upstream conduit It is desirable that the height difference with the position is almost the same as the overhead drop.

  In addition, it is desirable that the upstream side conduit has an increased or decreased flow path area in accordance with an increase or decrease in the amount of sewage flowing into the upstream conduit.

  That is, as shown in FIG. 5, when the upstream side conduit 206 made of a tube having a certain degree of rigidity, such as a vinyl chloride tube, is used, if the amount of sewage is greatly reduced, The flow path is not filled with sewage, and a water surface is formed in the vicinity of the outlet in the upstream side conduit, so that the potential energy of the so-called overhead drop: ΔH cannot be effectively used. On the other hand, as shown in FIG. 6, when the upstream side conduit 6 whose flow path area is reduced according to the decrease in the amount of inflow of sewage is used, even if the amount of inflow of sewage is reduced, the flow in the upstream side conduit is reduced. Since the road is filled with sewage, the potential energy of the overhead drop: ΔH can be used effectively.

  Here, as the “upstream water guide pipe whose flow path area increases or decreases according to the increase or decrease in the amount of inflow of sewage”, for example, a hose made of a synthetic resin fiber or the like, or a lower half of a vinyl chloride pipe In this case, the upper and lower halves made of non-woven fabric made of synthetic resin fibers are joined. In this way, when the flow rate of sewage is increased or decreased by using a cloth or the like that is easily lost when the internal pressure is reduced in the upstream water conduit itself or a part of its circumference, the compressive force is lost. Accordingly, the channel area can be increased or decreased.

  The vent pipe includes, in order from the upstream side, a downward flow portion inclined downward, a substantially horizontal horizontal flow portion, and an upward flow portion inclined upward, and is a bottom surface of the upward flow portion. The sediment collecting pipe accumulated in this portion is communicated with the upstream pipe at a position separated from the lowermost end of the upward flow portion by at least the pipe diameter of the upward flow portion. It is desirable that an air pipe for pressurizing air is communicated in the vicinity of the communication portion with the flow portion.

  That is, in the present invention, as described above, by effectively using the velocity energy and positional energy of the upstream sewage, the sewage flow force is increased, thereby preventing the accumulation of impurities. In addition, if the presence or absence of accumulation of foreign substances can be inspected, the sewer pipe can be more reliably prevented from being blocked by cleaning in advance. In the present invention, the place where the accumulation of impurities first occurs is assumed to be a bent connection portion between the horizontal flow portion and the upward flow portion of the vent pipe. Therefore, a sediment collection pipe is connected to this portion, and air is injected into the collection pipe from the air pipe, so that the collected sediment floats up to the outlet of the collection pipe, so that the presence or absence of sediment is appropriately determined. And can be easily inspected.

  By the way, a long overpass pipe that lies under an obstacle such as a river often requires a long period of time for inspection, cleaning, or repair. Therefore, two or more pipes are usually provided side by side. In the improved conventional structure shown in FIGS. 11 to 12, a Y-shaped diversion groove that is divided into two branches is provided on the bottom surface of the upstream manhole 504, and an outlet portion of the diversion groove divided into two is divided. In addition, each vent pipe of the two-line pipe is connected. Each of the diversion grooves divided into two branches is provided with a gate valve or the like.

  Normally, a vent pipe connected to one of the diversion grooves is opened by opening one of the diversion grooves divided into two branches and closing the other diversion groove. use. When this one vent pipe needs to be cleaned or repaired, the other vent pipe is used by reversing the opening and closing of the gate valve. However, such a conventional structure is open to the atmosphere, and cannot effectively utilize the velocity energy and potential energy of the upstream sewage as described above.

  Therefore, in the overlying structure of the sewage pipe according to the present invention, the vent pipe is a double pipe and includes a downstream manhole located at the outlet of the vent pipe. In addition, the upstream sewage pipe and each of the two pipes can be detachably connected alternately in an airtight state from the outside through the respective upstream water conduits in the upstream manhole. It has become. Further, each of the two pipes and the downstream sewage pipe can be detachably connected to each other through the respective downstream water guide pipes in the downstream manhole.

  Here, the upstream side conduit and the downstream conduit are not limited to two different types in order to be connected to each of the two conduits, but the upstream conduit and the downstream conduit are not limited. By using a flexible hose or the like that can be bent or stretched for each water pipe, it is possible to make one type.

  By connecting the vent pipe and at least the upstream sewage pipe in a sealed state, it is possible to effectively utilize both sewage velocity energy and potential energy. As a result, the sewage flow force can be increased, and impurities can be prevented from accumulating. Further, the upstream sewage pipe and the vent pipe are detachably connected in the upstream manhole by the upstream water guide pipe, thereby facilitating maintenance and inspection such as cleaning and repair of the vent pipe.

  Set the bottom position of the outlet of the upstream conduit to the same level as the bottom position of the communication section between the outlet of the vent pipe and the downstream sewage pipe. By making the difference approximately the same height as the overhead drop, a sufficient potential energy difference is provided between the upstream sewer pipe and the downstream sewer pipe, thereby increasing the sewage flow force in the vent pipe. It is possible to prevent the accumulation of impurities. In addition, by setting the upstream side conduit to increase or decrease the flow area in accordance with the increase or decrease in the amount of inflow of sewage, even if the amount of inflow of sewage decreases, the water surface position is lowered into the vent pipe. By avoiding this, the potential energy due to the overhead drop can be used effectively.

  A sampling pipe is installed near the upstream part of the vent pipe, and deposits are levitated by the pressurized air, making it easy to check for deposits and pre-cleaning to ensure clogging of the sewage pipe. Can be prevented. In addition, each of the two vent pipes can be connected to an upstream sewer pipe and a downstream sewer pipe alternately in a sealed state and detachably by the upstream and downstream water pipes. By doing so, maintenance / inspection such as cleaning and repairing of the bent pipe composed of the two-line pipe becomes easy.

  With reference to FIGS. 1 to 4, a specific example of the underground structure of the sewer pipe according to the present invention will be described. FIG. 1 shows a cross-section of an underground structure of a sewer pipe that passes under a river. A vent pipe 1 communicates with an upstream sewage pipe 2 and a downstream sewage pipe 3 that are located across the river. is doing. An upstream manhole 4 is provided at a communication portion between the upstream sewage pipe 2 and the inlet of the vent pipe 1, and a downstream manhole 5 is provided at a communication portion between the outlet of the vent pipe and the downstream sewage pipe 3. It is provided. The vent pipe 1 is composed of a downward flow portion 11 inclined downward, a substantially horizontal horizontal flow portion 12 and an upward flow portion 13 inclined upward from the upstream side.

  Further, the upstream sewage pipe 2 and the inlet of the vent pipe 1 are connected in an airtight state from the outside by an upstream water conduit 6. Similarly, the outlet of the vent pipe and the downstream sewage pipe 3 are connected downstream. The side water conduit 7 is connected in a sealed state from the outside. The bottom surface position at the outlet of the upstream water conduit 6, that is, the bottom surface position at the connection position with the inlet of the vent pipe 1 is the bottom surface position where the outlet of the vent pipe 1 and the downstream sewage pipe 3 communicate with each other, that is, the downstream manhole. 5 is set at almost the same height as the bottom surface of the central portion. Further, the difference in height between the bottom surface position of the inlet of the upstream side conduit 6, that is, the bottom surface position that communicates with the upstream sewage pipe 2, and the bottom surface position of the outlet side of this upstream conduit, that is, the bottom surface position that communicates with the inlet of the vent pipe 1. Is set to be almost the same as or slightly smaller than the overhead drop.

  As shown in FIGS. 1 and 2, the upstream manhole 4 is made of a concrete cylinder, elliptic cylinder, or square cylinder, and the upper part opens to the ground surface, and this opening is a lid (not shown). .) Further, a diversion groove 43 having a U-shaped cross section is provided on the bottom surface with an inclination. This inclination is such that the height difference between the upper end and the lower end of the flow guide groove 43 is substantially the same as or slightly smaller than the overhead drop. The upper and lower ends of the flow guide grooves 43 communicate with through holes 41 and 42 provided in the upstream manhole 4, respectively. The upstream side sewer pipe 2 and the inlet of the vent pipe 1 are inserted into the through holes 41 and 42, respectively, and both ends of the upstream side water guide pipe 6 are connected to these ends and the inlet by clamps 8 and 8, respectively. It is connected in a sealed state from the outside. The outer bottom surface of the upstream water conduit 6 is locked to the bottom of a U-shaped flow groove 43.

  The upstream side conduit pipe 6 uses a variable cross-sectional area pipe whose flow path area increases or decreases according to the increase or decrease of the amount of inflow of sewage. Specific configurations of the variable cross-sectional area tube are shown in FIGS. That is, when it is assumed that the amount of inflowing sewage is significantly reduced, as shown in FIG. 3, a hose 61 made of an airtight non-woven fabric that does not expand and contract is used for the upstream side conduit 6 and both ends are chlorinated. The flange portions 62 and 63 made of vinyl are attached. The flange portions 62 and 63 are detachably attached to the upstream sewage pipe 2 and the inlet of the vent pipe 1 by clamps 8 and 8 in the upstream manhole 4.

  When it is assumed that the amount of inflowing sewage does not decrease so much, as shown in FIG. 4, a half portion 161 of a hose made of an airtight nonwoven fabric whose upper half does not expand and contract is used for the upstream side conduit 106. In the lower half, one using a vinyl chloride halved portion 164 is used. Note that flange portions 162 and 163 made of vinyl chloride are attached to both ends. The flange portions 162 and 163 are detachably attached to the upstream sewage pipe 2 and the inlet of the vent pipe 1 by clamps 8 and 8 in the upstream manhole 4.

  In the downstream manhole 5, the detachable downstream water guide pipe 7 uses a pipe made of vinyl chloride having a constant cross-sectional area.

  Further, the upstream side conduit pipes 6 and 106 composed of the above-described variable cross-sectional area pipes are extended in length, and have a diameter that can be inserted and fitted into the upstream side sewage pipe 2, and further upstream positions in the upstream side sewage pipes. It is also effective to insert up to. That is, when the amount of sewage decreases, the position of the water surface in the upstream sewage pipe 2 shown in FIG. 6 moves to a position further upstream in the upstream sewage pipe. This can increase the sewage flow force.

Now, as shown in FIG. 7, the sediment collection pipe 91 is formed in the bottom surface of the upward flow portion 13 of the vent pipe 1 and in the opening hole 91 a provided at a position slightly away from the lowermost end in the upward direction. One end of the is in communication. In addition, one end of an air pipe 92 that press-fits air is communicated with the sampling pipe 91 in an opening 92 a provided at a position slightly away from the communication location with the upward flow portion 13. When the angle of the upward flow portion 13 with respect to the horizontal line: θ is 45 degrees or more, the distance L between the center of the opening hole 91a and the lowermost end of the upward flow portion is the tube of the upward flow portion. Diameter: Desirably 1/3 or more of D. When θ is less than 45 degrees, the distance: L is desirably equal to or greater than the tube diameter: D. This is because impurities are easily deposited at these positions.

  The other ends of the sampling tube 91 and the air tube 92 are both connected to a measurement chamber 93 provided on the ground surface. The other end of the air tube is pressurized by an electric or manual compressor. Air can be introduced. That is, the deposit inspection apparatus 9 is constituted by these equipments. Note that the measurement chamber 93 may be provided in the downstream manhole 5.

  Now, when the pressurized air from the compressor is introduced from the other end of the air pipe 92, air enters from the opening hole 92a provided in the collection pipe 91, and rises in the collection pipe as a droplet. Then, it is attracted to the rising air droplets, and the deposit S5 is sucked from the opening hole 91a provided in the upward flow portion 13, and rises in the collection tube 91 together with the air droplets, and is positioned in the measurement chamber 93. It floats at the other end of the sampling tube 91 to be used. Therefore, the presence or absence of the deposit S5 in the upward flow portion 13 can be easily checked by checking whether or not the deposit is mixed in the floating droplet.

  In the case where the vent pipe 1 has a small diameter, by introducing pressurized air into the upward flow portion 13 via the air pipe 92, the deposit S5 is suspended in the upward flow portion and removed. It is also possible to clean.

  FIG. 8 shows the structure of the sewage pipe overhang when the vent pipe is composed of the double pipes 301A and 301B. FIG. 8A shows a case where one vent pipe 301A of the two strips is used and the other vent pipe 301B is used as a spare. In addition, one vent pipe 301A is connected to the upstream sewage pipe 302 in a sealed state by the upstream water guide pipe 306A in the upstream manhole 304 by the method described above. Similarly, in the downstream side manhole 305, the downstream side sewer pipe 303 is connected in a sealed state by the downstream side conduit pipe 307A.

  FIG. 8B shows a case where the other vent pipe 301B used as a spare is used when the above-described one vent pipe 301A is inspected, cleaned, or repaired. That is, in the upstream manhole 304 and the downstream manhole 305, the upstream side conduit 306A and the downstream conduit 307A are removed by loosening the clamp 308, and another upstream conduit 306B and downstream conduit. 307B is connected to the upstream sewage pipe 302, the other vent pipe 301B that has been reserved, and the downstream sewage pipe 303 by clamps 308, respectively.

  Therefore, when switching to the spare vent pipe, it is only necessary to replace the upstream / downstream conduit pipes in the upstream / downstream manhole, so that the switching work can be performed easily and in a short time. If a flexible hose or the like that can be bent or extended is used for the upstream side conduit and the downstream side conduit, respectively, the upstream side conduit and the downstream conduit are connected to the upstream sewage conduit 302. It is possible to switch from one vent pipe 301A to the other vent pipe 301B without removing from the downstream sewer pipe 303.

  In addition, although the above-described structure of the sewer pipe is mainly suitable for a shunt-type sewer pipe, it is not limited to this shunt-type but can also be applied to a sewer pipe that joins rainwater or the like.

  It can be widely used in industries related to the manufacture of parts and equipment related to the laying of sewer pipes and civil engineering work.

It is a schematic sectional drawing of the underground structure of a sewer pipe. It is a partial expanded sectional view of an upstream manhole part. It is a perspective view of the upstream side water conveyance pipe which consists of a cross-sectional area variable pipe. It is a perspective view of the other upstream water guide pipe which consists of a cross-sectional area variable pipe. It is a schematic sectional drawing which shows the water surface position in the upstream water guide pipe in which a cross-sectional area does not change when the amount of sewage decreases. It is a schematic sectional drawing which shows the water surface position in the upstream water guide pipe which consists of a variable cross-sectional area pipe | tube when the amount of sewage decreases. It is a schematic sectional drawing which shows the means to check the deposit of a vent pipe. It is a top view which shows the switching method of the vent pipe which consists of a 2-line pipe. It is sectional drawing which shows the outline | summary of the underground structure of the sewer pipe by a prior art example. It is a partially expanded sectional view which shows the upstream manhole part by a prior art example. It is sectional drawing which shows the outline | summary of the underground structure of the sewer pipe by the improved type conventional example. It is a partially expanded sectional view which shows the upstream manhole part by the improved type prior art example.

Explanation of symbols

1, 301-501 Vent pipe (Pushing pipe)
11, 511 Downflow section 12, 512 Horizontal flow section 13, 513 Upflow section 2, 202-502 Upstream sewage pipe 3, 303-503 Downstream sewage pipe 4, 204-504 Upstream manhole 5,305 505 Downstream side manhole 6, 106 to 306 Upstream side conduit 7, 307 Downstream side conduit 8 Clamp 9 Sediment inspection device 91 Sediment collection tube 92 Air tube

Claims (5)

An upstream sewage pipe and a downstream sewage pipe located between obstacles such as rivers and underpasses, a vent pipe that penetrates under this obstacle, and an upstream manhole located at the entrance of this vent pipe,
The upstream sewage pipe communicates with the inlet of the vent pipe in a sealed state from the outside via an inclined upstream water conduit.
The outlet of the vent pipe communicates with the downstream sewer pipe,
In the upstream manhole, the upstream water conduit is detachable from the upstream sewage pipe and the inlet of the vent pipe, respectively. In Claim 1, the bottom surface position of the outlet of the upstream conduit pipe is substantially the same height as the bottom surface position of the communication portion between the outlet of the vent pipe and the downstream sewage pipe,
The sewage pipe overhang structure characterized in that the height difference between the inlet position and the outlet position of the upstream conduit is substantially the same as the overhead drop. 3. The lower side conduit according to claim 1, wherein the upstream side conduit has a flow passage area that increases or decreases in accordance with an increase or decrease in the amount of sewage flowing into the upstream conduit. Water pipe overhang structure. 4. The vent pipe according to claim 1, wherein the vent pipe includes, in order from the upstream side, a downward flow portion inclined downward, a substantially horizontal horizontal flow portion, and an upward flow portion inclined upward. Prepared,
At the bottom surface of the upward flow portion, at least a part of the diameter of the upward flow portion from the lowermost end of the upward flow portion, a collection pipe for deposits deposited on this portion communicates. And
An underground structure for a sewage pipe, wherein an air pipe for injecting air is communicated with the sampling pipe in the vicinity of a communicating portion with the upward flow section. The vent pipe according to any one of claims 1 to 4, wherein the vent pipe is a double pipe,
A downstream manhole located at the outlet of the vent pipe,
The upstream sewage pipe and the two pipes can be detachably connected to each other in the upstream manhole in a state of being sealed from the outside via the respective upstream water conduits. There,
Each of the two pipes and the downstream sewage pipe can be connected to each other in a detachable manner alternately through the respective downstream water guide pipes in the downstream manhole. Water pipe overhang structure.

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