JP2736964B2 - Deep underground drainage facilities and drainage pumps - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention collects inflow water, such as rainwater, flowing into a waterway including a small river into an inflow waterway provided underground, and guides the collected inflow water to a pumping station to discharge the river to a discharge destination. Deep underground drainage facilities to be discharged to the sea.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 4-363427 discloses an example of a deep underground drainage facility. As shown in FIG. 8, the drainage is collected from the surface of the ground or small rivers 3 and 5 near the surface and the drainage channel 4 through the shaft 2 to the underground waterway 1 arranged at a deep underground, and the underground waterway is collected. 1 to a pump well 7 at a pumping station provided at the downstream end of
And discharges water to the major river 9 where the water is discharged.

Further, an underground reservoir 10 having a certain volume is buried in the middle of the underground waterway 1 and the surface of the ground, and the side wall of the underground reservoir 10 and the underground waterway 1 are connected by a communication shaft 11, thereby causing heavy rainfall. The rise of the water level exceeding the hydraulic gradient 20 indicated by the one-dot chain line assumed in the case of the above is stored, and the overflow of the drainage from the shaft 2 to the ground is suppressed. The drainage stored in the underground reservoir 10 is dropped into the underground waterway 1 by opening the on-off valve 13 of the communication pipe 12 provided at the bottom as necessary, or is pumped up by the pump 15 and is effectively used for watering or the like. It has become.

[0004] In this way, in the event of heavy rain or the like, a sufficient time can be taken from the time when the flowing water reaches the pump well 7 to the time when the operation of the drain pump is started, thereby contributing to the stable operation of the drain pump system.

[0005]

In the above prior art,
Since the drainage pump 8 is provided underground at the same depth as the downstream end of the underground waterway 1, there is a problem to be solved, such as high construction costs, including excavation costs for the drainage pump station. .

[0006] The storage capacity of the above-mentioned underground reservoir 10 according to the prior art depends on the predicted amount of inflow to the pump station and the drainage pump 8.
The storage capacity of the underground waterway 1 is set to be equal to or greater than the storage capacity required from the conditions such as the drainage capacity of the groundwater.
Usually, the cost of excavating the underground waterway 1 occupies a large part of the construction cost of the deep underground drainage facility. Therefore, if the storage capacity of the underground reservoir 10 is to be increased to reduce this, the storage capacity of the underground reservoir 10 is reduced. Must be increased. It may be difficult to secure a site for the underground reservoir 10 having such a large storage capacity at a location away from the drainage pumping station, or to operate the pump 15 or the on-off valve 13 and perform maintenance and inspection. There are issues that need to be solved, such as the need for personnel and equipment.

Further, there is a problem to be solved in that the operation control of the drainage pump 8 in the deep underground drainage facility having the underground waterway 1 and the underground reservoir 10 is not considered.

An object of the present invention is to provide a deep underground drainage facility and a drainage pump which solve the above-mentioned problems.

[0009]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems by the following means, and through a vertical waterway (vertical waterway) at the downstream end of an underground waterway provided in a deep underground. Providing a water absorption tank for the drainage pump, positioning the impeller of the drainage pump at approximately the bottom level of the water absorption tank,
In addition, a pump suction port is provided so as to communicate with the water absorption tank. In other words, the bottom level of the water absorption tank is provided at a position that is shallower underground than the upper end position of the downstream end of the underground waterway.

It is preferable that the water absorption tank has a large storage capacity.

[0011] Further, at least three or more drainage pumps are provided in the drainage pumping station, and a large-capacity storage tank having a temporary storage effect of drainage flowing into the drainage pumping station in communication with the drainage pumping station or the underground waterway; A pump control device for controlling the three or more drainage pumps in accordance with the flow rate to be drained.

[0012]

According to the above-described means, the problems to be solved by the present invention can be solved by the following operations.

[0013] First, since the water suction tank of the drainage pump is provided at the downstream end of the underground waterway through the vertical waterway, in other words,
The bottom level of the water absorption tank is located shallower than the upper end of the downstream end of the underground waterway, so the drainage pump can be installed at a shallower depth below the ground. Can be reduced. In addition, since the bottom surface level of the water absorption tank has become shallow, the maximum head of the drainage pump required to bring the water level of the water absorption tank to a predetermined minimum water level can be reduced, and the cost of the water drainage pump can be reduced. In this case, the underground channel will be operated as a closed channel.

Further, it is preferable that a large-capacity water-absorbing tank is formed by positioning the upper end of the water-absorbing tank on or near the ground surface and forming the tank wall vertically. Thereby, the overflow of water from the underground waterway to the ground due to the storage effect can be reduced, or the diameter of the underground waterway can be reduced. As a result, the construction cost can be reduced, and it is suitable when it is difficult to secure a site for an underground reservoir at a position away from the drainage pump station.

In particular, by using the water-absorbing tank as a large-capacity storage tank, compared with a case where these are separately provided,
Construction costs can be reduced.

Further, the stable operation of the deep underground drainage facility can be ensured by the storage effect of the water absorption tank.

[0017] Further, by providing at least three or more drainage pumps at the drainage pumping station and appropriately controlling the operation of the drainage pump in accordance with the flow rate to be drained, the stable operation of the deep underground drainage facility can be further improved. .

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view showing a conceptual configuration of the deep underground drainage facility of the present embodiment. As shown in the figure, an underground waterway 1 is buried deep underground, and rainwater or the like flows into the underground waterway 1 from a water discharge channel 3, a sewer 4, a river 5 or the like via a shaft 2. The downstream end of the groundwater channel 1 is the pump well 7 of the drainage pump station.
The inflow water flowing into the pump well 7 is guided to a drain pump 8 via a water absorption tank 6, and is drained to a discharge destination large river or the like via a discharge water tank 10 by the drain pump 8. A drain pump station 11 is constituted by the water absorption tank 6, the pump well 7, the drain pump 8, the discharge tank 10, and the like.

In particular, the bottom surface level of the water absorption tank 6 is provided at a position shallower underground than the upper end position of the downstream end of the underground waterway 1. The water absorption tank 6 is connected to a pump well 7 connected to the downstream end of the underground waterway 1. In other words, the bottom of the water absorption tank 6 communicates with the upper end of the vertical water channel using the pump well 7 as a vertical water channel. The drain pump 8 is provided such that the position of the impeller is located substantially at the bottom level of the water absorption tank 6, and the pump suction port communicates with the water absorption tank 6. The storage capacity of the water absorption tank 6 is set to be large enough to reduce the risk of water overflowing from the underground waterway 1 to the ground and to reduce the diameter of the underground waterway 1.

As described above, according to this embodiment, the water absorption tank 6 of the drainage pump 8 is provided at the downstream end of the underground waterway 1 via the pump well 7 which is a vertical waterway. Since the bottom level of 6 is provided at a position shallower underground than the upper end position of the downstream end of the underground waterway 1, the drainage pump 8 can be provided at a shallower position underground. Construction costs can be reduced.

In addition, since the bottom surface level of the water absorption tank 6 has become shallower, the maximum head of the drainage pump required to bring the water level of the water absorption tank 6 to a predetermined minimum water level can be lowered, and the drainage pump 8 Cost can also be reduced. In addition,
In this case, the underground waterway 1 is operated as a closed waterway.

The upper end of the water absorption tank 6 is located at or near the surface of the ground, and the wall of the tank is formed vertically to form a large-capacity water absorption tank 6, so that the storage effect allows water to flow from the underground waterway 1 to the ground. Overflow can be reduced or the diameter of the underground waterway 1 can be reduced. As a result, it is suitable when it is difficult to secure a site for an underground reservoir at a position distant from the drainage pumping station or when it is easy to acquire a site for installing a large-capacity water absorption tank 6. Can be reduced. In addition, the storage effect of the water absorption tank 6 enables stable operation of the deep underground drainage facility in the closed channel operation.

Here, FIGS. 2A and 2B, FIGS. 3 and 4
According to FIG. 1, it will be described that the total head of the drain pump 8 can be reduced with reference to FIG. FIG. 2 (a)
FIG. 2 is an explanatory diagram of a case where the underground waterway 1 is operated as a closed channel, similarly to the embodiment of FIG. 1, and FIG. 2B is an explanatory diagram of a case where the underground waterway 1 is operated as an open channel. Generally, the total pump head H is a value obtained by adding the discharge pipe loss to the actual pump head Ha, and can be expressed by the following equation. H = (discharge water tank water level) − (water level at pump startup) + (discharge pipe loss) For example, as shown by the solid line in FIG. 3, the actual pump head Ha is 57 m, and the discharge pipe loss is 3.5 m. For example, the total head H becomes H = 57m + 3.5m = 60.5m. As shown by the dotted line in FIG. 3, in the open channel operation, it is planned that the rated flow rate can be obtained in the entire head H where water is pumped from the minimum water level LWL.

However, in the case of closed channel operation, drainage at a rated flow rate is required when the underground waterway 1 is full and the water level has risen halfway through the shaft 2. As shown in FIG. 2A, if the actual pump head Ha from the highest water level HWL of the closed channel is 35.5 m, the loss of the discharge pipeline is 3.5 m, so that the total head H is H = 35. 0.5m + 3.5m = 39.0m. That is, as compared with FIG.
With 9.0 / 60.5 = 0.644, it can be reduced to 64.4%.

For example, the water level when the drain pump 8 shown in FIG. 2A is started is set to 30% to 90% of the pipe diameter 10 m of the underground waterway 1.
In this case, the pump installation position is 3 m longer than that of FIG.
It can be installed up to 9m above, and the excavation work cost is reduced.

That is, in this embodiment, as shown in FIG. 1, the water absorption tank 8 is set at a level higher than the downstream end of the underground waterway 1.
Since the bottom surface of the pump and the impeller of the drainage pump 8 are located, in other words, the water level at the time of starting the pump at the rated flow rate is set to a high water level, the capacity of the drainage pump 8 can be reduced, The output of the diesel engine that drives the engine can be reduced, and fuel consumption is reduced.

On the other hand, the underground waterway 1 has a large-capacity temporary storage effect over a long distance.
It has a capacity of about 780,000 m ³ at 0 km and a capacity of 200 m ³ / S
The ec pump has a storage time of about 60 minutes. Therefore, in the case of the closed channel operation, the allowance of the storage time allows the water level at which the operation of the drain pump 8 starts to be set upward. Then, by sharing the storage capacity to the large-capacity water storage tank 6, the pipe diameter of the underground waterway 1 can be reduced. By reducing the pipe diameter of the underground waterway 1, the excavation cost of the underground waterway 1, which accounts for most of the construction cost of the deep underground drainage facility, can be reduced. Further, hunting of frequent stoppage of operation of the drainage pump 8 can be prevented by the storage effect.

FIG. 4 is an overall plan view of a drainage system to which the deep underground drainage facility of FIG. 1 is applied. As shown in the figure, in the drainage system of this embodiment, a drainage pump station 11 is arranged near a discharge river, and drainage such as rainwater is drained by a drainage channel 21 including a small river disposed in a drainage target area. The wastewater is collected and led to a drainage pumping station 11 where it is discharged to a river. The drainage channel 21 is formed from the underground waterway 1, which is a main waterway, and a plurality of branch pipes 22 to 25. The drainage pump station 11 is configured similarly to the embodiment of FIG. 1, and is provided with a pump control device 26 for controlling the operation of the drainage pump 8.

A water level detector 27 (a, b) is provided at an upstream point a of the branch pipe line 22 and at a point b downstream of the point.
But also at an upstream point e and a downstream point f of the branch pipe line 25,
A water level detector 27 (e, f) is provided for each.
These water level detectors 27 are for detecting the water level in the branch pipeline, and may have a known configuration such as a capacitance type or an ultrasonic type. The water level detection value at each point detected by the water level detector 27 is transmitted to the pump control device 26 by communication equipment (not shown). In addition,
A water level detector is not provided in the other branch pipelines 23 and 24, but may be provided as necessary. That is, since it is only necessary to detect a flash flood having a large flow rate and reaching the drain pump station 11 at the earliest and predict the arrival time, the present embodiment takes into consideration the overall configuration of the drainage system, topography, etc. A branch pipe line close to the pump station 11 and covering a large drainage target area is targeted, and a flash flood is detected in the branch pipe line.

In the drainage system configured as described above, the pump control unit 26 normally operates the drainage pumps P ₁ , P ₂ , P ₂ , P _{2 based on} the internal water level of the drainage pump station 11.
The drainage capacity of such speed and number of operating P ₃ automatically controlled to adjust the amount of waste water. Further, automatic control is performed based on a well-known inflow amount prediction.

Referring now to FIG. 5, the detailed configuration of the embodiment of FIG. 4 relating to the detection of flash flood and the prediction of the arrival time at the pump point of the flash flood will be described together with the operation. fundamentally,
The detection of the flash flood and the estimation of the arrival time are based on the water level data detected by the water level detectors 27a and 27b and 27e and f.
This is executed by the pump control device 26. Pump control device 2
6 includes a computer, and a water level detector 27a
5 is taken in every predetermined sampling period, subjected to normal input signal processing, stored in a data table of a memory, and the stored water level data is read out as shown in FIG. Such processing is executed.

FIG. 5 shows a process related to a flash flood generated in the branch pipe line 22. Note that the same processing is performed for the branch pipeline 25, and therefore, only the branch pipeline 22 will be described here. The occurrence (downflow) of flash flood is detected in the processing of steps 31 and 32. The change pattern of the water level in the case of flash flood is a pattern that increases rapidly. Therefore, in this embodiment,
The water level detection value ha (t) at the upstream point a is sampled, and the difference from the water level detection value ha (t + 1) one cycle before is calculated by Equation 1 to obtain the water level increase rate Δha (t) ( Step 31).

[0033]

Δha (t) = ha (t) −ha (t + 1) Next, the occurrence of flash flood is detected based on whether or not the increase rate Δha (t) is equal to or greater than a predetermined value k of a flash flood determination standard. (Step 32). If this determination is negative, the process returns to step 31 and repeats the same process for the next data. If affirmative, in step 33, the maximum water level hm of the flash flood is detected. This detection is performed by monitoring the change in the water level detection value ha (t) in the data table, and specifying the detection value indicating the maximum value as the highest water level. When the maximum water level is detected, a timer is set at the timing, and actual measurement of the time when the flash flood reaches the downstream point b is started (step 34). When a flash flood is detected, an alarm or the like may be issued based on the detection signal, or the fact and the occurrence point may be displayed on a display device such as a graphic panel. In addition to the flash flood detection,
It can be detected as a condition that the water level itself exceeds a predetermined set value or that the turbidity of the drainage becomes abnormally high.

The following steps 35 to 43 are steps for obtaining a correction coefficient α for improving the accuracy of prediction of the flash flood arrival time by hydraulic calculation. As a principle used for estimating the arrival time, various methods can be considered from a well-known hydraulic model. In this embodiment, a simple method using a stepped wave model is applied in consideration of the processing time of the estimation. The propagation speed (flow velocity) ω of the flash flood according to the step model is expressed by Expression 2. Note that this model is for a rectangular pipeline, but for a circular pipeline, the variables may be modified and applied in accordance with it.

[0035]

(Equation 2)

Here, ho is the initial water level at the front of the flash flood, and V is the initial flow velocity at the initial water level ho, which is obtained by equation (3). G is the gravitational acceleration.

[0037]

(Equation 3)

Here, n is the roughness coefficient of the pipeline, and I is the gradient of the pipeline. Therefore, if the flow velocity ω is obtained, the arrival time to reach the downstream point of the same drainage pipe can be obtained by dividing the distance to that point by ω.

According to the above hydraulic theory, the initial flow velocity Va at the point a is obtained by the equation 3 in step 35. Next, at step 36, the falling velocity ωa is obtained by the equation (2). Then, in step 37, a predicted value T′ab of the arrival time to the downstream point b separated by the distance Lab is calculated by Expression 4.

[0040]

## EQU4 ## T'ab = Lab / .omega.a In the next steps 38 to 40, flash flood detection at the point b and the maximum water level hm are detected. The details of this processing are the same as those in steps 31 to 33, and a description thereof will be omitted. At the timing when it is detected that the flash flood reaches the highest point at the point b in Step 40, the timer is stopped (Step 41), and the actual measurement value Tab of the arrival time from the point a to the point b is obtained (Step 42). And Step 4
In step 3, the correction coefficient α for the predicted time is calculated by the following equation (5).

[0041]

Α = T′ab / Tab Since the measured value is usually larger than the theoretically predicted value, α ≦ 1.0.

Next, the predicted time T'bd for the flash flood to reach the pump point d from the point b is calculated by the following equation (6).

[0043]

T′bd = α (T′bc + T′cd) The predictions of T′bc and T′cd in Equation (6) basically use Equations (2), (3) and (4), respectively. However, since the underground waterway 1 has different pipe line conditions such as the pipe diameter of the branch pipe line 22, the initial water level ho
And the highest water level hm are estimated by proportional calculation based on the detected value of the point a. In this case, it is necessary to consider the amount of wastewater flowing into the junction c from the other branch pipes 23, 24, 25, etc., in the initial water level ho. Therefore, it is preferable to install a water level detector at the junction c to detect the initial water level ho. However, when the flash flood of the branch pipeline 22 reaches the junction c the earliest, the amount flowing into the junction c from the other branch pipeline is a normal flow rate. A correlation coefficient based on the actual data of the flow rate ratio or the like is set, and the initial water level at the point a can be multiplied by the correlation coefficient to estimate the initial water level at the junction c. This embodiment is based on this method. In the present embodiment, basically, it is only necessary to predict the arrival time of the flash flood reaching the drainage pump point, so that the flash flood generated in the branch pipe 25 rather than the branch pipe 22 reaches the junction c first. When it reaches, the arrival time T′fd is predicted for the flash flood in the branch pipe line 22.

In step 45, based on the predicted arrival time T'bd, the number of drain pumps to be operated and the operation start timing are determined.
According to the determination, the control of the preliminary standby operation for the flash flood is performed. Normally, a plurality of drainage pumps are provided, and the number of drainage pumps to be operated is determined according to the strength of flash flood.

As described above, according to the present embodiment, the water level of the drainage channel is detected at the upstream point a of the drainage channel, and it is determined whether or not the rate of increase is sharp. Can be detected quickly. Thereby, the corresponding operation of the drain pump can be performed with a margin.

The degree of flash flood (water level or rate of increase)
And, based on the distance from the flash flood detection point to the drain pump point and the drainage channel conditions, the arrival time of the flash flood to the drain pump point is predicted and calculated according to hydraulic theory, so that there is more room for drainage. The corresponding operation of the pump can be performed. Since the number of the drainage pumps to be operated in advance and the operation start timing are determined based on the prediction result, it is possible to easily cope with the arrival of the flash flood.

Next, FIG. 6 shows a specific embodiment of a drainage pump suitable for the embodiment of FIG. The drainage pump according to the present embodiment is a vertical drive multiple pump, and FIG. 6 is a longitudinal sectional view of a pump station in which the drainage pump is arranged. As shown, 3
Reference numeral 1 denotes a driving device of a pump, and a main shaft 32 is in a vertical direction. 33 is a large capacity, low head pump, and 34 is a small capacity, high head pump, which is arranged in the vertical direction.
Reference numeral 35 denotes a joint capable of transmitting and non-transmitting the rotational torque. The main shaft 32 of the drive unit 31 is connected to the respective main shafts 36 of two pumps 33 and 34 arranged vertically by the joint 35. . That is, the drive unit 31 is located between the two pumps 33 and 34 disposed in the vertical direction, and has a double-hook drive configuration (not shown in detail). 37 is an intake shaft which is connected to the inflow water channel as an intake tank, 38
Is a discharge pipe related to the discharge flow path. Two or more units vertically disposed between the intake shaft 37 and the discharge pipe 38 (FIG. 6)
In this case, a vertical drive multiple pump composed of two pumps is arranged. The suction pipe 39 of the upper pump 33 is connected to the upper part of the intake shaft 37 via a gate valve 40, and the suction pipe 41 of the lower pump 34 is connected to the intake shaft 3 via a gate valve 42.
7 is connected to the lower part. The discharge sides of the pumps 33 and 34 are connected to a discharge pipe 38 via gate valves 43 and 44.

The water flowing into the intake shaft 37 from the inflow water channel flows into the suction pipes 39 and 41 when the gate valves 40 and 42 are open, and is discharged to the discharge pipe 38 by the pump. The discharge pipe 38 has a larger sectional area from a position where the discharge flows of the large-capacity, low-head pump 33 converge. Gate valve 4 on the discharge side
Numerals 3 and 44 are closed when the pump is stopped to prevent reverse flow of the discharge flow. 45 and 46 are water flow directions;
48 indicates a water level.

Since the drainage pump of this embodiment is configured as described above, it does not require a plane space for an underground drainage pumping station as compared with a case where two pumps are arranged side by side.

The main shaft 32 of the driving machine 31 and the pump 3
Since the main shafts 36 and 34 are connected by the joint 35 capable of transmitting / non-transmitting the rotational torque, only necessary pump impellers can be rotated, and waste of energy can be prevented.

Further, the two pumps 33 and 34 disposed in the vertical direction are large-capacity, low-head pumps 3 on the upper side.
3. Since the lower side is configured as a pump 34 having a small volume and a high head, the pump 34 having a high head is operated when the water level of the intake shaft 37 is a low water level 47 and the water level 48 of the intake shaft 37 is high. At times, a low head pump 33 can be operated. In addition, they can be operated simultaneously. Further, the driving device 31 has a simplified configuration in which both pumps are driven.

Further, since the discharge pipe having the flow path cross-sectional area increasing in the downstream direction is provided, efficient operation is possible. Further, one discharge pipe 3 is provided for a plurality of pumps.
8 can be used in combination, which also has the effect of simplifying the configuration of the pump device.

As described above, according to the present embodiment, when the large-capacity low-pump pump 33 is not operated, the gate valves 40 and 43 before and after the pump 33 are closed to drain the water, and the pump 33 is connected to the flywheel. It has the effect of saving energy and preventing water hammer.

FIG. 7 is a longitudinal sectional view of a drainage pump station in which a vertical drive multiple pump according to still another embodiment is arranged. In the figure, components having the same reference numerals as those in FIG. 6 are the same as those in the previous embodiment, and the description thereof is omitted.

In the embodiment shown in this figure, the impeller rotation axes of the three pumps 50 arranged in the vertical direction are in the horizontal direction, and the three pumps 50 have the same structure. In the drawing, reference numeral 31 denotes a driving machine serving as a driving source of a pump (or a pump impeller), 32 denotes a main shaft of the driving machine 31, and 50 denotes two or more machines arranged in a vertical direction (3 in the example of FIG. 7). ), 51 are three axial pumps 50
And 52 are shaft joints for connecting the main shaft 32 of the drive unit 31 and the respective connection shafts 51 of the axial pump 50. The axial flow pump 50 includes an axial flow type impeller 53 and guide blades 54 and 55. Reference numeral 56 denotes a rotation axis of the impeller 53 in the horizontal direction. Reference numeral 57 denotes a bevel gear related to an orthogonal transmission mechanism for transmitting the torque of the connection shaft 51 to the rotation shaft 56 of each impeller, and 58 denotes a shaft penetration opening provided in the casing of the axial flow pump.

The rotating shaft 56 and the bevel gear 57 of each impeller are
They are connected by a joint 35 capable of transmitting and not transmitting a rotational torque.

There is a pump chamber between the intake shaft 37 connected to the inflow water channel and the discharge pipe 38, and the pump chamber is disposed vertically.
A vertical-axis drive multiple axial-flow pump including three or more (three in FIG. 7) axial-flow pumps 50 is arranged. Each axial flow pump 5
The upstream side of the valve 0 communicates with the intake shaft 37 via a gate valve 59, and the downstream side communicates with the discharge pipe 38 via a gate valve 60.

In the case of this embodiment, similarly to the embodiment shown in FIG. 6, an economical pumping station configuration and efficient operation of the pump are enabled, and the rotary shaft 56 of the impeller 53 of each pump is provided. Are horizontally arranged, so that the pump impeller is not limited to the axial-flow impeller, and it is also possible to incorporate a mixed-flow impeller.

In this embodiment, the height of the water outlet at the outlet of the discharge pipe 38 is constant, and the water in the intake shaft 37 acts as a push. The head required for each axial pump 50 is the same, and the pumps can have the same structure. In addition, since the pumps have the same structure, the concept of a package type can be realized, and there is an effect peculiar to this embodiment that the pump can be easily added and the product cost can be reduced.

Although various embodiments have been described above with respect to a deep underground drainage facility, the present invention includes embodiments in which the techniques described in the above embodiments are appropriately combined and implemented.

[0061]

According to the present invention, since the suction tank of the drainage pump is provided at the downstream end of the underground waterway via the standing waterway, in other words, the bottom level of the water absorption tank is set at the upper end position of the downstream end of the underground waterway. Since the drainage pump is provided at a shallow position underground, the drainage pump can be provided at a shallow position underground, so that the excavation work cost and the construction cost of the drainage pump station can be reduced. In addition, since the bottom surface level of the water absorption tank has become shallow, the maximum head of the drainage pump required to bring the water level of the water absorption tank to a predetermined minimum water level can be reduced, and the cost of the water drainage pump can be reduced.

Further, by forming a large-capacity water absorption tank,
Due to the storage effect, overflow of water from the underground waterway to the ground can be reduced, or the diameter of the underground waterway can be reduced. As a result, the construction cost can be reduced, and it is suitable when it is difficult to secure a site for an underground reservoir at a position away from the drainage pump station. In particular, by using the water-absorbing tank as a large-capacity reservoir, the construction cost can be reduced as compared with the case where they are separately provided.

Further, by providing at least three or more drainage pumps at the drainage pump station and appropriately controlling the operation of the drainage pump according to the flow rate to be drained, the stable operation of the deep underground drainage facility can be further improved. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a deep underground drainage facility of the present invention.

FIG. 2 is a diagram illustrating a pump starting water level when performing open channel operation and closed channel operation.

FIG. 3 is a diagram illustrating pump characteristics of a drain pump.

FIG. 4 shows a plan view of the entire drainage system to which the present invention is applied.

FIG. 5 is a flowchart illustrating an example of a procedure of flash flood detection and arrival time prediction of the drainage system.

FIG. 6 is a longitudinal sectional view showing an embodiment of a vertical drive multiple pump according to the present invention.

FIG. 7 is a longitudinal sectional view showing another embodiment of the vertical drive multiple pump according to the present invention.

FIG. 8 is a sectional view showing a schematic configuration of a conventional deep underground drainage facility.

[Explanation of symbols]

 Reference Signs List 1 groundwater channel 2 shaft 3 drainage channel 4 sewer 5 river 6 water absorption tank 7 pump well 8 drainage pump 10 discharge water tank 11 drainage pump station 26 pump control device

Claims (3)

(57) [Claims] An underground waterway which is disposed at a large depth underground and into which drainage such as rainwater flows in from a drainage channel including a small river, a water absorption tank communicated with a downstream end of the underground waterway, A drain pump for sucking water and pumping it to a discharge destination near the surface of the ground, wherein a bottom surface of the water absorption tank is connected to the underground water channel through a vertical water channel, and the drain pump is located at a position of the impeller. A deep underground drainage facility, which is located substantially at the bottom level of the water absorption tank, and is provided with a pump water suction port connected to the water absorption tank. 2. A drain pump for sucking water flowing into the bottom of a water absorption tank through a vertical water channel from a downstream end of an underground water channel disposed deep underground and pumping it to a discharge destination near the surface of the ground. A drain pump having a pump impeller positioned substantially at the bottom level of the water absorption tank and a pump water suction port communicating with the water absorption tank; 3. The drainage pump according to claim 2, wherein a bottom surface level of the water absorption tank is provided at a position below the lower end of the underground waterway below the upper end of the underground waterway.