JP2006104714A - Method and device for preventing blocking of underground water pumping facility, and blocking preventive underground water pumping facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a device for preventing blocking of a pumping facility while continuing to pump. <P>SOLUTION: Air supply pipes 21 leading close to the underground water level H1 are provided in a pumping well 11 of the pumping facility 10 continuously pumping underground water W, and an underground water upper space P in the pumping well 11 is filled with low reactive gas G through the air supply pipes 21. Low reactive gas G is continuously supplied at a flow rate corresponding to the leakage speed of low reactive gas G from the upper space P to suppress oxidation of underground water components. When sidewalls of the pumping well 11 are provided with water collecting passages 31 facing the side, it is preferable to lead the air supply pipes 21 into the water collecting passages 31 from the inside of the pumping well 11 to fill the upper space P and the internal spaces of the water collecting passages 31 with the low reactive gas. It is further preferable to provide an oxygen analyzer for measuring oxygen concentration in the underground water upper space P in the pumping well 11 and to fill the low reactive gas G so that the oxygen concentration in the upper space P is not more than the oxidation suppressing concentration of the underground water components. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clogging prevention method and apparatus for groundwater pumping equipment and a clogging prevention type groundwater pumping equipment, and more particularly, a method and apparatus for preventing clogging due to oxidation of groundwater components in a pumping equipment for continuously pumping groundwater, and clogging using the same. It relates to prevention-type groundwater pumping equipment.

  When building large structures on the ground or underground (reactor buildings, oil storage tanks, gas storage tanks, etc.), prevention of floating structures due to groundwater, water resistance measures for structures, rational design of structures, etc. For this purpose, a pumping facility (sometimes called a drainage facility) that lowers the groundwater level below the structure may be provided. As shown in FIG. 5, Non-Patent Document 1 discloses the structure of a groundwater pumping facility provided in a structure 3 that is a reactor building of a nuclear power plant in this case. The pumping facility in the illustrated example includes a drain pipe 32 that is laid directly under the foundation of the structure 3 and collects groundwater in the rock 1, a water collection pipe 31 that is laid around the foundation of the structure 3 and collects water from the drain pipe 32, It consists of a pumping well 11 that discharges the groundwater of the water pipe 31 to the ground. Reference numeral 34 in the figure indicates a turbine building adjacent to the reactor building.

  The drain pipe 32 in FIG. 5 is a perforated PVC pipe having a pipe diameter of φ = 100 mm, for example, and the arrangement position and number are selected based on the uplift analysis of the surrounding rock mass 1 of the structure 3. The water collecting pipe 31 is, for example, a perforated fume pipe having a pipe diameter of φ = 800 mm. Based on the analysis of the amount of spring water in the surrounding rock mass 1, the water collecting pipe 31 and the drain pipe 32 have a larger flow capacity than the spring water volume. Select the diameter. The pumping well 11 is composed of a RC water collecting pit 14 constructed approximately 38.7m underground and a steel cylinder (shaft) extending from the water collecting pit 14 to the ground. The water collecting pit 14 is charged with a pump (not shown). The groundwater collected in the drain pipe 32 and the water collection pipe 31 is caused to flow down to the water collection pit 14, and the groundwater level in the water collection pit 14 is continuously discharged to the ground with a pump to lower the groundwater level below the structure 3. The lifting pressure acting on the structure 3 is reduced.

  Further, as shown in FIG. 6, when building or other structure 3 is constructed on the ground 1 where the clay layer ground 42 is distributed below the sand layer ground 41 which may be liquefied, the liquid of the sand layer ground 41 For the purpose of preventing water pollution, a pumping facility for lowering the groundwater level below the structure 3 may be provided (see Patent Document 1). The structure 3 in FIG. 6 is supported by a pile foundation 45 that is dug up to a deep position in the sand layer ground 41 and is embedded in a support layer 43 below the clay layer ground 42. Around the structure 3, a water blocking wall (reinforced concrete underground continuous wall, steel sheet pile, etc.) 46 that reaches the clay layer ground 42 is constructed to surround the structure 3, and the clay layer ground 42 from the bottom surface of the structure 3 The groundwater level of the sand layer ground 41 is lowered by continuously discharging the groundwater of the sand layer ground 41 surrounded by the water blocking wall 46 through the pumping well 11 and the pumping device 15. The liquefaction of the sand layer ground 41 at the time is prevented. The same pumping equipment is also used when a groundwater level lowering method (pumping method) is applied in underground excavation work of a gravel layer having a high groundwater level (see Patent Document 2).

  All of the above-described groundwater pumping facilities are important facilities for maintaining and managing structures or construction sites, and it is necessary to continue pumping a necessary and sufficient amount of groundwater for a long period of time. However, as shown in FIG. 5 and FIG. 6, the pumping equipment is provided deep underground, and there is a risk that the function will deteriorate over time due to the influence of dissolved components in the groundwater penetrating from the surrounding ground. For example, in the pumping facility shown in FIG. 5, if the surrounding ground 1 contains iron, iron ions that have entered the pumping facility are oxidized by air (oxygen) to produce insoluble iron hydroxide. Insoluble oxide substances gradually accumulate in the water collecting pit 14, the water collecting pipe 31, and the drain pipe 32 to block them. When the pumping well 11, the water collecting pipe 31, and the drain pipe 32 are blocked, the amount of groundwater determined by the above-described pumping pressure analysis and spring water analysis cannot be drained, and measures such as providing a new pumping well 11 are required. For this reason, conventionally, a worker regularly goes down to the water collecting pit 14 of the pumping well 11 and performs a cleaning operation to manually remove insoluble oxide substances accumulated in the pumping well 11 by blowing high-pressure water or the like.

Satoru Yasuda et al. “Design and Construction of Onagawa Nuclear Power Station Unit 3 Groundwater Drainage System” Electric Power Engineering No. 294, Japan Electric Power Engineering Association, July 2001, pp.59-63 JP-A-11-323896 JP 2001-323477 A

  However, the above-described cleaning method for the pumping well 11 involves a dangerous work in which the worker gets down into the deep underground pumping well 11, and the pumping water must be interrupted during the cleaning work to ensure the safety of the worker. is there. For this reason, in a pumping facility that requires continuous discharge of groundwater, it is necessary to provide a plurality of pumping wells 11 including a reserve well in consideration of cleaning work. In order to discharge groundwater economically with the minimum number of pumping wells 11 without reserve wells, it is necessary to develop a technique for preventing the blocking of pumping wells without interrupting pumping.

  In addition, the conventional method for cleaning the pumping well 11 has a problem in that the deposits in the water collecting pipe 31 and the drain pipe 32 connected to the side of the pumping well 11 cannot be sufficiently removed. For example, in the pumping facility shown in FIG. 5, it is difficult for a worker who has descended into the water collecting pit 14 to enter the water collecting pipe 31 and the drain pipe 32, and the sediment inside the water collecting pipe 31 and the drain pipe 32 is sufficiently removed. Since it cannot be removed, there is a risk that the water collecting pipe 31 and the drain pipe 32 may be blocked by the conventional cleaning method. Development of a technique capable of preventing clogging of all parts of the pumping facility 10 including the water collecting pipe 31 and the drain pipe 32 is desired.

  Accordingly, an object of the present invention is to provide a blockage prevention method and apparatus for preventing blockage of a pumping facility while continuing pumping.

Referring to the embodiment of FIG. 1, the method for preventing clogging of a groundwater pumping facility according to the present invention includes an air pipe 21 that reaches the vicinity of the groundwater level H ₁ in a pumping well 11 of a pumping facility 10 that pumps groundwater W continuously. The low-reactive gas G is filled into the groundwater upper space P in the pumping well 11 through the air pipe 21 and the flow rate is in accordance with the leakage rate V of the low-reactive gas G from the upper space P. G is continuously replenished to suppress oxidation of groundwater components. Preferably, when the lateral water collecting channel 31 is provided on the side wall of the pumping well 11, the air supply pipe 21 is introduced into the water collecting channel 31, and the low-reactive gas G is introduced into the upper space P and the water collecting channel 31. Fill.

Also in reference to the block diagram of FIG. 1, obstruction prevention apparatus of groundwater pumping installation according to the invention, feed opening into groundwater level H ₁ near the inside pumping well 11 of pumping equipment 10 for continuously pumping the groundwater W trachea 21, the air supply device 22 for filling the groundwater upper space P in the pumping well 11 with the low reactive gas G through the air supply pipe 21, and the low reactive gas G leakage rate V from the upper space P A control device 25 for controlling the flow rate of the gas device 22 is provided. Preferably, as shown in FIG. 2, an oxygen concentration meter 28 for measuring the oxygen concentration in the groundwater upper space P in the pumping well 11 is provided so that the oxygen concentration in the upper space P is equal to or lower than the oxidation suppression concentration of the groundwater component. The flow rate of the air supply device 22 is controlled.

Further, referring to the embodiment of FIG. 1, the blockage prevention type groundwater pumping facility according to the present invention is a pumping facility 10 that lowers the groundwater level H below the ground or underground structure 3, just below or around the structure 3. pumping well 11 reaching the ground water layers were drilled through the pumping continuously pumping to pumping equipment 15 the ground water W in well 11, feed pipe 21 open to the groundwater level H ₁ near the inside pumping well 11, feed pipe 21 The air supply device 22 that fills the groundwater upper space P in the pumping well 11 with the low reactive gas G, and the flow rate of the air supply device 22 according to the leakage velocity V of the low reactive gas G from the upper space P is controlled. The control device 25 is provided.

  The method and apparatus for preventing clogging of a groundwater pumping facility according to the present invention fills the groundwater upper space in the pumping well with a low reactive gas via an air pipe reaching the vicinity of the groundwater level, and leaks the low reactive gas from the upper space. Since the low-reactive gas is continuously replenished at a flow rate according to the above and the oxidation of the groundwater component is suppressed, the following remarkable effects are exhibited.

(A) Since the pumping equipment can be prevented from being blocked without stopping the pumping work, it is not necessary to provide a reserve well, and economical pumping with the minimum number of pumping wells can be realized.
(B) Not only the inside of the pumping well, but also blockage of all parts of the pumping equipment including the inside of the water collecting channel and the drain pipe connected to the side of the pumping well can be effectively prevented.
(C) It is possible to reduce the necessity of periodic cleaning work involving dangerous work, and to prevent the pumping well from being blocked safely and at low cost.
(D) It can be easily applied to existing pumping wells, and can be effectively prevented from being clogged simply by arranging an air pipe.
(E) The flow rate of low-reactive gas can be automatically controlled, and it can contribute to labor saving and automation of pumping equipment when combined with an automatic pumping system.

  FIG. 1 shows an embodiment in which the present invention is applied to a pumping facility 10 provided in a structure 3 such as an underground LNG (liquefied natural gas) storage tank constructed to a depth reaching a groundwater layer in the ground 1. The pumping facility 10 in the illustrated example pumps ground water from a drain pipe 32 that collects groundwater directly under the foundation of the structure 3, an annular water collecting pipe 31 that surrounds the drain pipe 32, and a water collecting pit 14 that is connected to the water collecting pipe 31. And a pumping well 11. For example, the ground 1 is dug down to the groundwater layer, the drain pipe 32, the water collecting pipe 31, and the water collecting pit 14 are laid, and the drain pipe 32 and the water collecting pipe 31 are backfilled with crushed stone or sand to form the drain layer 6 and collect the water. The pumping well 11 extending from the pit 14 to the ground is installed, and the structure 3 and the pumping equipment 10 are integrally constructed by placing concrete on the drain layer 6 so as to surround the structure 3 and the pumping well 11. The arrangement position, number, diameter, etc. of the drain pipe 32 and the water collecting pipe 31 can be designed in the same manner as in FIG. The present invention can be effectively applied to the pumping equipment 10 having the water collecting pipe 31 and the drain pipe 32 as shown in FIGS. 1 and 5. For example, the pumping equipment 10 without the water collecting pipe 31 and the drain pipe 32 is used as shown in FIG. Is also applicable.

The pumping facility 10 in the illustrated example has a pumping device 15 that pumps water through a pumping well 11, and continuously drains groundwater W flowing from the drain pipe 32 and the water collecting pipe 31 to the water collecting pit 14 into the drainage groove 5 on the ground. It discharged, lowering than groundwater level H ₀ surrounding groundwater level H ₁ of the drain layer 6. By lowering the water table H ₁ of the drain layer 6, to reduce the uplift acting on the structure 3, foundation structure 3 is prevented from submerged groundwater. And pump 17 and riser pipe 16 to the pumping device 15, a control device of the pump 17, including a measuring device for underground water level H ₁ or H _0, water pumps as drainage layer 6 is suitable groundwater level H ₁ 17 can be controlled automatically.

Further, the pumping facility 10 in the illustrated example has a blockage prevention device that fills the groundwater upper space P of the pumping well 11 with the low-reactive gas G, and dissolved components in the groundwater W while continuing the pumping work by the pumping device 15. Oxidation of (for example, iron ions) is suppressed and deposition of insoluble oxidizing substances (for example, iron hydroxide) is prevented. The blockage prevention apparatus in the illustrated example has an air supply pipe 21 that opens near the groundwater level H ₁ in the pumping well 11, and a low-reactive gas G that fills the groundwater upper space P of the pumping equipment 10 through the air supply pipe 21. The air device 22 includes a control device 25 that controls the flow rate of the air supply device 22. The illustrated pumping facility 10 has four wells connected to the water collecting pipe 31, one of which is a pumping well 11 and the other three are reserve wells 12. For example, when the pumping well 11 is inspected, the groundwater W can be pumped using any of the reserve wells 12. However, in the present invention, even if only the pumping well 11 is used, the pumping work and the blocking prevention work can be performed simultaneously, and the reserve well 12 is not essential. When the reserve well 12 is provided, the reserve well 12 serving as an air entry path to the pumping equipment 10 is also provided with the air supply pipe 21 and the air supply device 22, and the inside of the pumping equipment 10 through the pumping well 11 and the reserve well 12 Is filled with a low-reactive gas G.

The air supply pipe 21 of the blocking prevention device is, for example, a metal hose or a suitable pressure resistant material hose. Even if the leading end of the air pipe 21 faces slightly above the groundwater level H ₁ of the drain layer 6 or the low reactive gas G is water-insoluble, the tip of the air pipe 21 may be opened in the groundwater. Good. In the example shown in the figure, the air pipe 21 is suspended inside the pumping well 11, but the air pipe 21 is installed in the ground 1 or the structure 3, and only the tip opening thereof is near the groundwater level H ₁ in the pumping well 11. You may make it come. Preferably, the front end opening of the air supply pipe 21 is introduced from the pumping well 11 into the water collection pipe 31 or the drain pipe 32, and the space in the water collection pipe 31 and the drain pipe 32 is also filled with the low-reactive gas G. In order to efficiently fill the entire pumping equipment 10 with the low-reactive gas G, it is effective to fill from the water collecting pipe 31 or the drain pipe 32. As shown in the example of the drawing, the tip of the air supply pipe 21 may be branched, one may be opened in the pumping well 11 and the other may be opened in the water collection pipe 31.

  Low reactive gases G are flammable substances (methane, ethane, propane, butane, etc.), explosive substances (oxygen, hydrogen, etc.), and hazardous substances (ammonia, chlorine, cyanide) at room temperature. -Inert gas or carbon dioxide such as argon, xenon, krypton, neon, helium, nitrogen, etc., excluding hydrogen sulfide. Preferably, the low-reactive gas G is nitrogen (a specific gravity of 0.967), argon (1.380), or carbon dioxide (1.529), which can be supplied in a large amount and has a specific gravity equal to or greater than that of air. When the pumping equipment 10 is made of concrete, it is desirable to avoid the use of carbon dioxide, which causes neutralization of concrete, and nitrogen gas is practical from the viewpoint of cost. The low reactive gas G may be a mixed gas thereof.

  In the illustrated example, the low-reactive gas G is nitrogen gas, and a nitrogen gas production device 23 or a storage tank is connected to the air supply device 22. For example, the production apparatus 23 produces nitrogen gas G (purity 99%) by vaporizing liquefied nitrogen or by passing compressed air through an oxygen adsorbent to produce high purity nitrogen gas, and the controller 25 controls the flow rate. However, the nitrogen gas G is sent into the air supply pipe 21 by the air supply device 22.

  According to the size of the pumping well 11, the control device 25 in the illustrated example sets the oxygen concentration in the groundwater upper space P to a concentration that does not oxidize dissolved components in the groundwater (hereinafter referred to as oxidation suppression concentration; for example, 1%) or less. It has a filling detection means 27 that stores the filling time T of the nitrogen gas G at a predetermined flow rate required for this. The pumping well 11 is filled with the nitrogen gas G by controlling the inflow of the nitrogen gas G by the air supply device 22 at a predetermined flow rate for at least the filling time T. The filling time T required for filling the nitrogen gas G can be determined in advance experimentally or empirically according to the size of the pumping well 11, the specific gravity of the nitrogen gas G with respect to the air, and the predetermined flow rate. Although there is a possibility that some air remains in the drain pipe 32 and the water collecting pipe 31, it is consumed for the oxidation of dissolved components in the groundwater W over time, so that the entire space of the pumping equipment 10 can be filled with the nitrogen gas G. Further, it is possible to store the filling time T of each spare well 12 in the filling detection means 27 and to fill the reserve well 12 with nitrogen gas G.

  Since the nitrogen gas G filled in the pumping well 11 has a specific gravity smaller than that of air, it gradually leaks according to the degree of airtightness of the pumping well 11. For this reason, after detecting the filling with the nitrogen gas G, the control device 25 continues to feed the nitrogen gas G at a feed flow rate that slightly exceeds the leakage velocity V of the nitrogen gas G, whereby the upper space P of the pumping well 11 The oxygen concentration of the water is kept below the oxidation inhibition concentration of the groundwater component. Since the leakage rate V of the nitrogen gas G varies depending on the size / tightness of the pumping well 11 and the specific gravity of the nitrogen gas G to the air, it is difficult to directly measure the leakage rate V from the pumping well 11. However, as described later, the present inventor can experimentally or empirically grasp the leakage rate V of the nitrogen gas G from the change in the oxygen concentration in the upper space P after the pumping well 11 is filled with the nitrogen gas G. I found it. It is desirable to provide an appropriate lid 13 at the upper opening of the pumping well 11 to suppress leakage of the nitrogen gas G as much as possible. The control device 25 in the illustrated example has storage means 26 that stores the leakage rate V of the nitrogen gas G for each pumping well 11 or reserve well 12, and the inflow rate of the infeed device 22 is set according to the leakage rate V. Control.

  As shown in FIG. 2, an oxygen concentration meter 28 for measuring the oxygen concentration is provided in the groundwater upper space P in the pumping well 11, and the control device 25 and the oxygen concentration meter 28 are connected to each other. Thus, it is possible to control the flow rate of the air supply device 22 so that the oxygen concentration in the upper space P is equal to or lower than the oxidation suppression concentration of the groundwater component. In this case, oxygen concentration meters 28 are provided at different depth positions in the pumping well 11, and the filling of the nitrogen gas G into the entire interior of the pumping well 11 can be detected by the plurality of oxygen concentration meters 28. However, in order to measure the oxygen concentration inside the deep pumping well 11, a large number of oxygen concentration meters 28 are necessary, and when the reserve well 12 is provided as shown in the figure, an oxygen concentration meter 28 is provided for each of them. Since it is necessary to provide an oxygen concentration meter 28, it may be difficult to install it practically and economically. The present invention does not require the oxygen concentration meter 28, and it is sufficient to control the flow rate of the air supply device 22 in accordance with the filling time T and the leakage speed V as described above.

[Experimental Example 1]
Using a pumping well 11 with a water collecting pipe 31 having a diameter of 1.2 m and a depth of 12 m as shown in FIG. 3, an experiment for confirming the effect of the blocking prevention device of the present invention was conducted. Pumping insert the flue 21 to the well 11 and to face the front end opening to 10~20cm about a position higher than the groundwater level H ₁ upon stopping of water pumps 17. The oximeters 28a, 28b, 28c and 28d are fixed at positions 6m, 4m and 2m deep in the upper space P of the pumping well 11 and directly under the lid 13, respectively. The recording means 27a was connected. First, nitrogen gas G is supplied to the air supply pipe 21 at a sufficiently large predetermined flow rate by the air supply device 22, and the filling time T until the oxygen concentration of each of the oxygen concentration meters 28a to 28d becomes substantially 0% is measured. did. After confirming the filling of the pumping well 11 with the nitrogen gas G, the supply of the nitrogen gas G was stopped, and the oxygen concentrations of the oxygen concentration meters 28a to 28d were recorded in the concentration recording means 27a every hour.

  FIG. 4 shows changes in oxygen concentration at positions 6 m, 4 m, and 2 m deep in the upper space P of the pumping well 11 after the supply of nitrogen gas G is stopped. Assuming that the oxygen concentration (oxidation inhibitory concentration) in the upper space P that does not oxidize dissolved components in groundwater is 1%, the elapsed time when the oxygen concentration of 0% is substantially equal to or greater than the oxidation inhibitory concentration is obtained from the experimental results of FIG. It can be seen that it is about 3.5 hours at a depth of 2 m, about 7.85 hours at a depth of 4 m, and about 12.1 hours at a depth of 6 m. That is, in the groundwater upper space P of the pumping well 11, the boundary position of the oxidation inhibition concentration gradually descends from the upper opening according to the leakage of the nitrogen gas G, and the descending speed of the boundary position is 0.57 (2 m depth). = 2 / 3.5) m / hour, 0.51 (= 4 / 7.85) m / hour at a depth of 4 m, 0.50 (= 6 / 12.1) m / hour at a depth of 6 m, and the average value is 0.53 m / hour Met. From the viewpoint of suppressing oxidation of the groundwater component, the rate of decrease of the boundary position of the oxidation suppression concentration can be considered as the leakage rate V of the nitrogen gas G.

From the experimental results shown in FIG. 4, the present inventor found that the pumping well 11 having a diameter of 1.2 m is approximately 0.60 m ³ (≈0.6 m × 0.6 m × 3.14 × 0.53 m≈) corresponding to the leakage velocity V of the nitrogen gas G described above. It was found that if the nitrogen gas G is continuously supplied in the vicinity of the groundwater level H ₁ at a flow rate of 600 liters), the oxygen concentration in the groundwater upper space P in the pumping well 11 can be maintained below the oxidation inhibition concentration. In addition, the present inventor also uses the low-reactive gas G from the upper space P in the same manner as in this experiment even when the diameter and depth of the pumping well 11 are different or when the low-reactive gas G other than nitrogen gas is used. It has been found that the leakage speed V can be experimentally determined from the descending speed of the boundary position of the oxidation inhibition concentration described above.

  Next, the blockage prevention device of FIG. 1 is applied to the pumping well 11 of FIG. 3, the filling time T and the leak rate V of the nitrogen gas G obtained in the above-described experiment are stored in the control device 25, An experiment was conducted to maintain the oxygen concentration in the space P below the oxidation suppression concentration of the groundwater component. When the control device 25 adjusts the infeed device 22 to a predetermined inflow rate and nitrogen gas G is continuously fed for more than the filling time T, the oxygen concentration in each of the oxygen concentration meters 28a to 28d becomes 1% or less. The upper space P of the pumping well 11 could be filled with nitrogen gas G. Further, after the filling was confirmed, the feed flow rate of the feed device 22 was adjusted to 600 liters / hour (= 10 liters / minute) corresponding to the leakage rate V of the nitrogen gas G described above, and the supply of the nitrogen gas G was continued. However, the oxygen concentrations of the oxygen concentration meters 28a to 28d were all maintained at 1% or less. That is, it was confirmed that the oxygen concentration in the upper space P of the pumping well 11 can be maintained below the oxidation inhibiting concentration of the groundwater component by the blockage preventing device of the present invention.

  Further, the present inventor collected the groundwater W of the pumping well 11 while maintaining the oxygen concentration in the upper space P of the pumping well 11 below the oxidation inhibiting concentration of the groundwater component, and the water quality (redox potential, dissolved oxygen concentration, The concentration of dissolved iron ions was investigated. As a result, it was confirmed that the dissolved oxygen concentration in the groundwater W was low and the dissolved iron ion concentration was high. From this, it was confirmed that the present invention can prevent the oxidation of iron ions in the groundwater W, and that the present invention is effective in preventing the deposition of iron hydroxide in the groundwater W.

  Thus, the “closure prevention method and apparatus for preventing blockage of the pumping equipment while continuing pumping”, which is the object of the present invention, can be achieved.

  FIG. 2 shows another embodiment of the blockage prevention type groundwater pumping facility 10 of the present invention. The pumping equipment 10 in the illustrated example is provided with a water treatment device 18 that removes an oxidation suppression target component (for example, iron ions) from the groundwater W pumped by the pumping device 15. In the pumping facility 10 of the present invention provided with the closure prevention device, since the dissolved components in the groundwater W are not oxidized in the pumping well 11, the water collecting pipe 31, and the drain pipe 32, the water is pumped by the pumping device 15 from the viewpoint of reducing the environmental load. It is desirable to remove the dissolved component (oxidation suppression target component) in the groundwater W before discharging into the drainage groove 5 later.

  In the water treatment apparatus 18 in the illustrated example, for example, an oxidizing agent such as sodium hypochlorite is added to the pumped ground water W to oxidize the oxidation suppression target component (for example, iron ions) in the ground water W, and thereby insoluble oxidizing substances (for example, After the formation of iron hydroxide), a polymer flocculant is added to agglomerate and precipitate insoluble oxides in a concentration precipitation tank. The precipitate is dehydrated with a filter press, and the dehydrated cake is disposed of as waste. Only the supernatant liquid overflowed in the concentration sedimentation tank is adjusted in pH and discharged into the drainage groove 5.

It is explanatory drawing of one Example of this invention. It is explanatory drawing of the other Example of this invention. It is explanatory drawing of experiment which calculates | requires the leak rate of the low reactive gas with which the pumping well was filled. It is a graph which shows an example of the experimental result of the leak rate of the low reactive gas by the experiment of FIG. It is explanatory drawing of the underground water pumping equipment of the conventional nuclear power building. It is explanatory drawing of the groundwater pumping equipment for the conventional liquefaction countermeasures.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ground (bedrock) 3 ... Structure 5 ... Drainage channel 6 ... Drain layer 10 ... Pumping equipment 11 ... Pumping well
12 ... Reserve well 13 ... Lid 14 ... Catchment pit
15 ... Pumping device 16 ... Pumping pipe 17 ... Pumping pump
18 ... Water treatment device 21 ... Air supply tube 22 ... Air supply device
23… Gas production equipment (gas tank) 25… Control equipment
26 ... Storage means 27 ... Filling detection means 27a ... Concentration recording means
28 ... Oxygen meter 29 ... Computer 31 ... Catchment pipe (collection channel)
32 ... Drain pipe 34 ... Turbine building
41 ... Sand layer ground 42 ... Clay layer ground 43 ... Support layer ground
45 ... Foundation pile 46 ... Water blocking wall G ... Low reactive gas (nitrogen gas) H ... Groundwater level P ... Upper space T ... Filling time V ... Leakage speed W ... Groundwater

Claims (12)

An air pipe that reaches the vicinity of the groundwater level is installed in the pumping well of the pumping facility that continuously pumps up the groundwater, and the low-reactive gas is filled in the upper space of the groundwater in the pumping well through the air pipe. A method for preventing clogging of a groundwater pumping facility, in which low-reactive gas is continuously replenished at a flow rate according to the leakage rate of the reactive gas to suppress oxidation of groundwater components. 2. The blocking prevention method according to claim 1, wherein an oxygen concentration meter is provided in an upper space of the groundwater in the pumping well, and is filled with a low-reactive gas so that the oxygen concentration in the upper space is equal to or lower than the oxidation suppression concentration of the groundwater component. How to prevent clogging of groundwater pumping equipment. 3. The blocking prevention method according to claim 1 or 2, wherein a side water collecting channel is provided on a side wall of the pumping well, and the air supply pipe is introduced into the water collecting channel so that a low reactive gas is introduced into the upper space and the water collecting channel. How to prevent clogging of filled underground water pumping equipment. 4. The blocking prevention method according to claim 1, wherein the low-reactive gas is nitrogen gas. An air supply pipe that opens near the groundwater level in a pumping well of a pumping facility that continuously pumps groundwater, an air supply device that fills the groundwater upper space in the pumping well through the air supply pipe, and the upper space An apparatus for preventing clogging of groundwater pumping equipment, comprising a control device for controlling the flow rate of the air supply device in accordance with the leakage rate of low reactive gas from the ground. The blockage prevention apparatus according to claim 5, wherein an oxygen concentration meter for measuring an oxygen concentration in an upper space of the groundwater in the pumping well is provided, and the air supply device is configured such that the oxygen concentration in the upper space is equal to or lower than an oxidation suppression concentration of a groundwater component. Blocking prevention device for groundwater pumping equipment by controlling the flow rate of water. The blockage prevention apparatus according to claim 5 or 6, wherein the low-reactive gas is nitrogen gas. In the pumping equipment for lowering the groundwater level below the ground or underground structure, the pumping well that reaches the groundwater layer directly below or at the periphery of the structure, the pumping device that continuously pumps the groundwater in the pumping well, An air supply pipe that opens near the groundwater level in the pumping well, an air supply device that fills the groundwater upper space in the pumping well through the air supply pipe, and a leak rate of the low reactive gas from the upper space A blockage prevention type groundwater pumping facility comprising a control device for controlling the flow rate of the air supply device accordingly. 9. The pumping facility according to claim 8, wherein the control device includes an oxygen concentration meter provided in an upper space of groundwater in a pumping well, so that the oxygen concentration in the upper space is equal to or lower than the oxidation suppression concentration of groundwater components. Blocking prevention type groundwater pumping equipment with controlled flow rate. The pumping equipment according to claim 8 or 9, wherein a drain layer is provided immediately below the structure, the pumping well is provided at a peripheral edge of the structure, a water collecting channel communicating with the drain layer is provided on a side wall of the pumping well, and the air pipe Blocking prevention type groundwater pumping equipment which is introduced into the catchment channel. The pumping equipment according to claim 8, wherein the low-reactive gas is nitrogen gas. The pumping equipment according to any one of claims 8 to 11, wherein a blockage-preventing type groundwater pumping equipment is provided with a water treatment device that removes an oxidation suppression target component from the pumped groundwater.

Images