JP5659566B2 - Pumping equipment, soft ground improvement method, ground excavation method, contaminated soil purification method, and condensate method - Google Patents

Description

  The present invention relates to a pumping device installed at the lower end of a well pipe and a pumping device having a pressure reducing unit for reducing the inner space of the well pipe, a soft ground improvement method and a ground excavation method using the pumping device, The present invention relates to a contaminated soil purification method that performs a pumping process for pumping up groundwater, and a condensate method that performs a recovery process that facilitates subsequent water injection by moving groundwater in the ground in a direction opposite to that during injection.

  As a groundwater level lowering method, a vacuum deep well method is known. In this vacuum deep well method, a well pipe having a strainer is buried in the soil, and a pump and a pressure reducing device are attached to the well pipe. By operating the decompression device, the inside of the well pipe is decompressed and a negative pressure is applied to the water level surface, so that the water head difference between the natural water level and the well pipe water level (virtual water level in the well pipe) is increased and drained.

  In this vacuum deep well construction method, as shown in FIG. 14, when the groundwater level is located below the upper end of the strainer 101 into which groundwater flows, air flows into the well pipe 102 together with the groundwater through the strainer 101. The decompression effect is reduced. Thus, there is an apparatus improved to have high water collection performance even when the groundwater level is lower than the upper end of the groundwater inflow portion.

  For example, as shown in FIG. 15, in Patent Document 1, a strainer pipe 201 provided with a strainer 200 capable of flowing groundwater into the inside, and an inner wall of the strainer pipe 201 are provided. There has been proposed a groundwater level lowering apparatus that is provided at a predetermined interval and includes an inner tube 203 having a water passage hole 202 at a lower end. In this apparatus, even if the groundwater level of the surrounding ground falls below the upper end of the strainer 200 where the groundwater flows in, the water between the inner cylinder and the strainer pipe 201 becomes a seal, so that the pressure reducing effect is maintained without air flowing in. Can do.

JP 2000-27170 A

  However, in the apparatus of Patent Document 1, the water level in the well pipe varies depending on the operation of the drain pump. For example, while the drainage pump is actively draining, the water level falls, and when the water level falls below the suction port of the drainage pump and the drainage pump is temporarily stopped, groundwater flows into the well pipe and the water level rises. It is very difficult for the apparatus of Patent Document 1 to achieve a balance so that the water level in the inner tube 203 is kept at a certain height. For this reason, the negative pressure which acts on the water level surface 204 cannot be exerted on the surrounding groundwater with a stable size, and there has been a problem that the amount of inflow into the well pipe of the groundwater becomes unstable.

  In addition, when the groundwater level around the well pipe is lower than the upper end of the groundwater inflow portion of the strainer 200, the portion from the upper end of the groundwater inflow portion to the groundwater level cannot be involved in the groundwater suction. There was a problem that the efficiency was lowered.

  This invention is made | formed in view of such a situation, and it aims at stabilizing the inflow into the well pipe of groundwater, and improving the inflow efficiency into the well pipe of groundwater.

The pumping device of the present invention is provided with a strainer at the lower end, a well pipe buried in the ground,
A closing lid that closes the inner space of the well pipe in an airtight state, a decompression section that depressurizes the inner space of the well pipe closed by the closing lid, and an upper end located above the groundwater inflow portion of the strainer A cylindrical side wall member having a height determined in this manner, and a pump storage portion including a bottom member joined in a liquid-tight state to a lower end of the side wall member, and in a storage space of the pump storage portion, the have a, and pumping pump suction port is installed at a position lower than the upper end of the side wall members, the inflow of water into the accommodating space, characterized in that done by overflow the side wall member And

  According to the present invention, when the water level in the well pipe is lowered to the height of the upper end of the side wall member due to the operation of the pump, the water level is lowered in the storage space in which the pump is stored, and the outer peripheral side of the side wall member. For, the water level becomes constant. Therefore, the groundwater that has passed through the side wall member flows into the storage space and is pumped up by the pump. Thus, on the outer peripheral side of the side wall member, the water level becomes constant at the height of the upper end of the side wall member, and does not become any lower. And, since the negative pressure for sucking the groundwater acts on the water level surface on the outer peripheral side than the side wall member, the suction force of the groundwater can be made constant, and the inflow of the groundwater into the well pipe can be stabilized. Can do. Moreover, since the water level of the groundwater around the well pipe does not become lower than the upper end of the strainer's groundwater inflow portion, the groundwater can be sucked from the entire strainer, and the inflow efficiency of the groundwater into the well pipe can be increased. .

  In the present invention, when the pump housing part has a leg member that supports the bottom member in a state where it floats from the bottom surface of the well pipe, the bottom of the well pipe is used as a sediment reservoir to pass through the strainer. Due to the inflowing earth and sand, the period until the well malfunctions can be lengthened.

  In this invention, when the bottom member with which the said pump accommodating part is equipped comprises the bottom face of the said well pipe, simplification of an apparatus structure can be achieved.

  Moreover, this invention is a soft ground improvement construction method including the pumping process which pumps up groundwater with the pumping apparatus of any one of Claims 1-3 installed in the improvement object location in the ground.

  According to the present invention, in improving the properties of a soft viscous ground, the efficiency of inflow of groundwater into a well pipe can be increased by increasing the negative pressure effect on the pumped well. As a result, groundwater can be quickly collected in the well pipe even in a soft viscous ground that is difficult to move water, and the properties of the ground can be improved in a short time.

  In addition, the present invention provides a retaining wall construction step of constructing a retaining wall at the boundary between the excavation site and the non-excavation site in the ground, and any one of claims 1 to 3 installed in the vicinity of the retaining wall. The excavation site in the state where the lifting pressure acting on the excavation site from the lower side with the decrease in the groundwater pressure is relaxed by the water pressure lowering step of lowering the groundwater pressure of the groundwater under pressure by the pumping device according to claim A ground excavation method including a ground excavation process for excavating the ground.

  ADVANTAGE OF THE INVENTION According to this invention, at the time of the water pressure fall of the pressurized groundwater in excavation construction, the effect of the negative pressure with respect to a pumping well can be improved, and the inflow efficiency into the well pipe of groundwater can be improved. As a result, a wide range of groundwater can be pumped in a state where the flow rate is stabilized by a single pumping device, so that the ground can be excavated while only a small number of wells are installed to prevent overburden.

  Moreover, this invention installs the pumping apparatus of any one of Claim 1 to 3 in the contaminated soil contaminated with the pollutant, and pumps up the ground water around the contaminated soil containing the pollutant. It is a contaminated soil purification method including a process and a pollutant treatment process for treating pollutants in the pumped groundwater on the ground.

  According to the present invention, since the effect of negative pressure during pumping can be enhanced in the pumping process, groundwater can be pumped from a wide range of ground by one pumping device, and the improvement range can be expanded. Can do. In addition, since the surrounding air is continuously sucked after the groundwater is pumped, it can be applied to purification when volatile pollutants remain in the soil.

  Further, the present invention provides a condensate well by injecting water into a condensate well provided in the ground and returning the water into the ground, and pumping up water in the inner space of the condensate well. It is a condensate construction method which performs the recovery process which improves the clogging of the circumference | surroundings, Comprising: The pumping apparatus of any one of Claim 1 to 3 is provided in the said condensate well, It is characterized by the above-mentioned.

  According to the present invention, in the recovery step, the effect of the negative pressure during pumping can be enhanced, so that the earth and sand that has an influence on a wide range of groundwater and is clogged at that position can be recovered. It can be moved to the water well side, and water can be smoothly injected into the ground in the subsequent condensate process through the flow path formed by this movement.

  According to the present invention, the inflow of groundwater into the well pipe can be stabilized, and the inflow efficiency of the groundwater into the well pipe can be increased.

It is sectional drawing explaining a pumping apparatus. It is sectional drawing which expands and shows the lower end part of a well well. It is A arrow line view in FIG. It is sectional drawing explaining the state before pumping up groundwater, and the state at the time of a pumping start. It is sectional drawing explaining the state which applies a negative pressure in a well pipe and discharges groundwater. It is sectional drawing explaining the state after continuing drainage in the state which applied the negative pressure in the well pipe. It is sectional drawing explaining the flow of the water in the lower end part of a well pipe. It is a figure explaining a soil property improvement construction method. It is a figure explaining the state before the ground excavation in a ground excavation construction method. It is a figure explaining the state after the ground excavation in a ground excavation construction method. It is a figure which illustrates a contaminated soil purification construction method typically. It is a figure which illustrates a recharge well construction method typically. It is a figure explaining the modification of a side wall member. It is a figure explaining a prior art. It is a figure explaining the improved prior art.

  Hereinafter, the water pumping apparatus which concerns on this invention is demonstrated.

  As shown in FIG. 1, the pumping device 2 includes a well pipe 3, a closing lid 4, a decompression pump 5, a pumping pump 6, and a pump storage unit 7.

  The well pipe 3 is a cylindrical member embedded in the ground G. In this embodiment, a steel pipe having a cylindrical shape with a diameter of 40 cm and a length of 30 m is used. In the illustrated ground G, the groundwater W penetrates and the groundwater surface is at a natural water level.

  As shown in FIG. 2, a strainer 8 is provided on the peripheral surface of the lower end portion of the well pipe 3. The strainer 8 is a portion that communicates the inside and the outside of the well pipe 3, and is composed of a wire 8b that is wound so as to surround the slit 8a provided in the well pipe 3 from the outside. Are spaced from each other so that they do not enter the well 3. Therefore, the groundwater W in the ground G flows into the well pipe 3 through the slit 8 a of the strainer 8. For this reason, the slit 8a corresponds to a groundwater inflow portion into which groundwater flows. Further, the bottom of the well pipe 3 is closed in a liquid-tight state by the bottom plate 10. The bottom plate 10 is made of a circular steel plate and welded to the lower end portion of the well pipe 3.

  As shown in FIG. 1, the closing lid 4 is a member that closes the upper end surface of the well pipe 3 in an airtight state. The closing lid 4 of the present embodiment is formed of a circular steel plate that is the same as or slightly larger than the outer diameter of the well tube 3 and is welded to the upper end of the well tube 3. Note that the blocking lid 4 may be provided at a position lower than the upper end of the well pipe 3 as long as it is a position higher than the natural water level of the groundwater W.

  The decompression pump 5 is a device that sucks out air from the inner space of the well pipe 3 through the intake pipe 11 and decompresses the inner space. The intake pipe 11 is a member that communicates the intake port of the decompression pump 5 and the inner space of the well pipe 3. The closing lid 4 is provided with an insertion port for inserting the intake pipe 11 through the plate thickness direction (not shown), and a gap between the insertion port and the intake pipe 11 is filled with a sealing material. It has been. When the decompression pump 5 is operated, the air in the well pipe 3 is sucked out through the intake pipe 11 and discharged outside, and the inner space is decompressed. Therefore, the combination of the decompression pump 5 and the intake pipe 11 corresponds to a decompression unit that decompresses the inner space of the well pipe 3.

  The pump 6 is a device that pumps up the ground water W that has flowed into the well pipe 3 through the strainer 8. In this embodiment, a deep well submersible pump with an output of 3.7 kwh is used. As shown in FIGS. 2 and 3, the pump 6 is installed at the lower end of the well pipe 3 in a state of being housed in the pump housing 7. And the water intake 12 for taking in water is provided in the peripheral surface lower end part of the pump 6. The water intake 12 corresponds to a groundwater inlet and is disposed at a position lower than the upper end 22 a of the side wall member 22.

  The pump 6 is connected to the lower end of a drain pipe 13. The drain pipe 13 is attached in the vertical direction along the well pipe 3. As shown in FIG. 1, the upper portion of the drain pipe 13 reaches the outside of the well pipe 3 through an insertion port provided in the closing lid 4. The gap between the insertion port and the drain pipe 13 is filled with a sealing material as in the intake pipe 11.

  As shown in FIGS. 2 and 3, the pump housing portion 7 includes a bottom member 21, a side wall member 22, and a leg member 23. And the storage space 7a in which the pumping pump 6 is accommodated is divided by joining the bottom member 21 and the side wall member 22 in a bottomed cylindrical shape.

  The bottom member 21 is a circular plate-like member on which the pumping pump 6 is installed, and partitions the bottom portion of the storage space 7a (the bottom surface of the side wall member 22). The diameter of the bottom member 21 is determined so as to be slightly larger than the pumping pump 6 and smaller than the inner diameter of the well pipe 3. The bottom member 21 of the present embodiment is made of a circular steel plate having a diameter of 32 cm. Moreover, in this embodiment, the pumping pump 6 is being fixed to the bottom member 21, and the pump storage part 7 is prevented from rising when the storage space 7a is emptied by pumping.

  The side wall member 22 is a cylindrical member that divides the side surface of the storage space 7a. In the present embodiment, the side wall member 22 is made of a steel cylindrical tube having a diameter of 32 cm. The lower end of the side wall member 22 is joined in a liquid-tight state to the outer peripheral portion of the bottom member 21 by welding. Thereby, the penetration | invasion of the water from the junction part of the side wall member 22 and the bottom member 21 to the storage space 7a is prevented. The inflow of water into the storage space 7a is caused by the water level in the gap between the well pipe 3 and the side wall member 22 (referred to as the inflow space 3a for convenience) rising and flowing over the side wall member 22.

  The height of the side wall member 22 is determined so that the upper end 22a of the side wall member 22 is higher than the upper end 8c of the slit 8a by a predetermined height or more. In the present embodiment, the height of the side wall member 22 is determined so that the upper end 22a of the side wall member 22 is higher than the upper end 8c of the slit 8a by a predetermined height X1 (10 cm in the present embodiment). Then, by providing a height difference between the upper end 22a of the side wall member 22 and the upper end 8c of the slit 8a, water that satisfies this range exhibits a sealing function that suppresses the ingress of air (details will be described later).

  The leg member 23 is provided on the lower surface of the bottom member 21 and supports the bottom member 21 in a state where it floats from the bottom of the well pipe 3. The leg member 23 is also made of steel, and the upper end is welded to the bottom surface of the bottom member 21. When the bottom member 21 is lifted from the bottom of the well pipe 3 by the leg member 23, the range X2 from the bottom surface of the well pipe 3 to the bottom member 21 can be used as a sediment reservoir, and the sediment flowing in through the strainer 8 It is possible to lengthen the period until the inside of the well pipe 3 is blocked and malfunctions. In addition, although compressed in the drawing, the range X2 is set to about 1 to 2 m, for example.

  As shown in FIG. 1, a filter FL is provided between the outer peripheral surface of the well pipe 3 and the ground G so as to surround the well pipe 3. This filter FL is formed, for example, by filling the gap between the well pipe 3 and the ground G with gravel. This filter FL has water permeability, and allows groundwater W that has exuded from the ground G to the periphery of the well pipe 3 to flow down while being filtered. The groundwater W flowing down the filter FL flows into the inner space of the well pipe 3 from the lower end of the well pipe 3 through the gaps between the wires 8b and the slits 8a. By providing this filter FL, it becomes easy to guide the groundwater W existing around the well pipe 3 to the strainer 8, and the inflow efficiency of the groundwater W into the well pipe 3 can be increased.

  Next, the operation of the aforementioned pumping device 2 will be described.

  When the operation of the pumping pump 6 is started from the state before the pumping shown in FIG. 4A, the water level WL1 in the well pipe 3 is lowered with the pumping as shown in FIG. 4B. Moreover, the water level WL2 in the ground G is also lowered. The water level WL2 has the lowest position of the filter FL and becomes higher as the distance from the position increases in the radial direction, as indicated by a broken line.

  As shown in FIG. 5A, when the water level WL1 in the well pipe 3 is lowered to about the upper end 22a of the side wall member 22, the operation of the decompression pump 5 is started, and the inner space of the well pipe 3 is vacuumed. Reduce pressure. This reduced pressure lowers the virtual water level in the well pipe 3. Thus, by lowering the virtual water level in the well pipe 3, the head difference from the natural water level outside the well pipe 3 becomes large, and the groundwater can flow into the well pipe 3.

  As a result, for example, as shown in FIG. 5B, the inclination of the water level WL2 in the ground G becomes gentler than the inclination of the water level WL2 in FIG. Can lower the groundwater level. If the operation is further continued, as shown in FIG. 6, the slope of the water level WL2 in the ground G becomes more gentle than the slope of the water level WL2 in FIG. The influence range of the water level fall outside the well pipe 3 can be widened.

  FIG. 7 is an enlarged view of a pumping portion in the present invention. Regarding the water level WL1 in the well pipe 3, when the water level WL1 is lowered to the height of the upper end 22a of the side wall member 22, as shown in FIG. 7, the water level surface WL1a of the storage space 7a is lowered thereafter, but the inflow space 3a. The water level surface WL1b (the gap between the well pipe 3 and the side wall member 22) does not descend. This is because the inflow space 3 a and the storage space 7 a are partitioned by the side wall member 22. This is the same even when almost the entire amount of water stored in the storage space 7 a is pumped up by the pump 6.

  Further, even if groundwater in the ground G flows into the well pipe 3, the water level surface WL1b of the inflow space 3a is maintained at the height of the upper end 22a of the side wall member 22. This is because the groundwater that has entered the inflow space 3 a is sucked up by the negative pressure in the well pipe 3, overflows the side wall member 22, flows into the storage space 7 a, and is pumped up by the pump 6.

  And at the time of attraction | suction of the groundwater W, the negative pressure for attracting | sucking groundwater acts on the water level surface WL1b of the inflow space 3a. Since the height of the water level surface WL1b is maintained, the suction force of the groundwater W can be stabilized, and consequently the inflow of the groundwater W into the well pipe 3 can be stabilized.

  Further, the upper end 22a of the side wall member 22 is provided at a position higher than the upper end 8c of the slit 8a by a predetermined height X1. For this reason, even if the level WL2 of the groundwater W in the vicinity of the strainer 8 is equal to or lower than the upper end 22a of the side wall member 22, the water existing between the upper end 22a of the side wall member 22 and the upper end 8c of the slit 8a It acts as a seal that makes it difficult for air from G to enter.

  That is, since the surrounding groundwater with a water guiding gradient flows into the well pipe 3, the groundwater blocks the intrusion of air in the ground G. As a result, even if the water level WL2 of the groundwater W reaches the upper end 8c of the slit 8a, a large amount of air is introduced to the inflow space 3a in the well pipe 3 so that the air in the ground G occasionally infiltrates into bubbles. The inventors have confirmed through experimentation that no continuous intrusion occurs. Thereby, the rapid pressure change in the well pipe 3 can be suppressed, and the reduced pressure state can be maintained. Thereby, inflow of the ground water W into the well pipe 3 can be performed stably.

  Furthermore, since the water level WL2 of the ground water W around the well pipe 3 does not become lower than the upper end 8c of the slit 8a, the ground water W can be sucked from the entire strainer 8. Thereby, the inflow efficiency of the groundwater W into the well pipe 3 can be increased, and the water level of the groundwater W can be lowered for the ground G in a wide range.

  Next, the soil property improvement construction method (soft ground improvement construction method) using the above-described pumping device 2 will be described.

  As shown in FIG. 8, in this soil property improvement method, the retaining wall 1 is constructed on the ground G to surround the improvement target portion G1 (the retaining wall construction step), and the pumping device 2 is installed in the improvement target portion G1. (Equipment installation process). If the pumping device 2 is installed, the operation of the pumping device 2 is started to lower the groundwater level (water level lowering step).

  When the pumping device 2 is operated, the water level WL2 in the ground G is lowered along with the pumping as described with reference to FIGS. As a result, the groundwater W can be pumped from a wide range of ground G by one pumping device 2, and the groundwater W at the excavation target location G1 can be discharged earlier than when a conventional well is used. Further, when the excavated ground is soft and viscous ground, surplus water in the ground G that is difficult to move to the well at the natural water level can be collected in a short time by the negative pressure of the vacuum. Thereby, the start of the dry work which removed water can be brought forward, and a construction period can be shortened.

  Next, the ground excavation method using the pumping device 2 will be described.

  As shown in FIG. 9, also in this ground excavation method, the earth retaining wall 1 is constructed on the ground G to surround the excavation site G1 (earth retaining wall construction process). In this construction process, the retaining wall 1 is constructed at the boundary between the excavation site G1 and the non-excavation site G2 in the ground G so as to surround the excavation site G1. Moreover, the pumping apparatus 2 is installed in the vicinity of the earth retaining wall 1 in the non-excavation location G2 (apparatus installation process). If the pumping device 2 is installed, the operation of the pumping device 2 is started to reduce the groundwater pressure of the groundwater under pressure (water pressure lowering step).

  By the operation of the pumping device 2, the water pressure in the pressurized aquifer G4 is lowered. As a result, the groundwater W can be pumped up from a wide range of aquifer G4 by one pumping device 2, and the lift acting on the excavation point G1 from the lower side can be reduced. If the water pressure is lowered, as shown in FIG. 10, the ground G in the range surrounded by the retaining wall 1 is excavated (ground excavation step). Thus, by excavating the ground in a state where the water pressure is reduced, the ground G can be excavated while preventing blistering.

  As described above, when the pumping device 2 is used for the ground excavation method, a wide range of groundwater W can be pumped, and therefore the number of wells (pumping devices) can be reduced as compared with the conventional method. Moreover, since the groundwater W can be pumped up in a short period of time, excavation of the ground G can be started early.

  Next, an application example in which the present invention is applied to a contaminated soil purification method will be described.

  As shown in FIG. 11, in this contaminated soil purification method, the above-described pumping device 2 is installed in the improvement target location G5 in the ground G. In the contaminated soil purification method, it is common that the location G5 to be improved has a depth of about several meters to several tens of meters from the ground surface. For this reason, in the pumping apparatus 2 of this embodiment, the length of the well pipe 3 becomes the depth according to the depth of the improvement object location G5, ie, the depth of about several m to several tens of meters.

  If the pumping device 2 is installed, the groundwater W is pumped up from the improvement target location G5 and introduced into the pollutant purification device installed on the ground. In this case, since the pumped-up groundwater contains pollutants, the pollutants are removed by a purification device after being pumped.

  Also in this embodiment, the groundwater W can be pumped up from the ground G of a wide range with the single pumping apparatus 2 similarly to 1st Embodiment. That is, contamination purification can be performed on a wide range of ground G. In addition, after the groundwater W is pumped up, the volatile contaminants remaining in the ground can be continuously removed by sucking the air in the ground G.

  Next, an application example in which the present invention is applied to the recharge well method (condensate method) will be described.

  As shown in FIGS. 12A to 12C, in the recharge well construction method of this embodiment, a deep well 32 (pumped well) and a recharge well 33 (condensate well) are used. And the water pumped up by the deep well 32 is returned to the ground G by the recharge well 33 (condensation process). Further, each of the deep well 32 and the recharge well 33 has the same structure as the pumping device 2 of the first embodiment. That is, the deep well 32 and the recharge well 33 include the water pumping device 2.

  As shown in FIG. 12A, if the water pumped up by the deep well 32 is continuously returned to the ground G through the recharge well 33 for a long period of time, clogging occurs on the recharge well 33 side, and the water is grounded. It becomes difficult to be injected into G. This is thought to be because the fine earth and sand in the ground G moved together with the injected water and blocked the water flow path. As a result, the water level of the recharge well 33 rises and it becomes difficult to inject water pumped up by the deep well 32.

  Therefore, as shown in FIG. 12B, a recovery process is performed in which the water existing in the recharge well 33 is pumped and the water and soil on the ground G are moved to the recharge well 33 side. In this recovery process, the operation of the pump 6 is stopped in the deep well 32, the pump 6 of the recharge well 33 is operated, and the decompression pump 5 is operated when the water level in the well pipe 3 is sufficiently lowered. As a result, as described in the first embodiment, a wide range of groundwater W moves to the recharge well 33 side.

  The earth and sand that caused the clogging by the movement of the groundwater W also move. For example, earth and sand flowing into the recharge well 33 is discharged to the outside together with water. Also, the earth and sand at a position away from the recharge well 33 moves somewhat toward the recharge well 33 side. Thus, the clogging caused by the earth and sand is eliminated by discharging and moving the earth and sand. If the clogging is eliminated, the condensing process is restarted as shown in FIG.

  In the recovery process of the recharge well 33, it is important to increase the head difference from the clogged position. For this reason, there is a limit to the lowering of the water level in the well in the natural water level, and it is effective to lower the virtual water level by applying a negative pressure in the vacuum well.

  Moreover, also in this embodiment, the inflow efficiency of the groundwater W into the well pipe 3 can be increased as in the previous embodiment. As a result, in the recovery process, a wide range of groundwater W and earth and sand can be moved to the condensate well side over a long period of time, and the ground G of the water in the subsequent condensate process through the flow path formed by this movement. Can be smoothly injected.

  As mentioned above, although preferred embodiment was described, this description is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents thereof. For example, you may be comprised as follows.

  For example, regarding the side wall member 22 of the pump storage part 7, if the inflow space 3a and the storage space 7a can be divided, it will not be restricted to a cylindrical shape. For example, as shown in FIG. 13A, a hexagonal tubular side wall member 22 'may be used. Further, as shown in FIG. 13B, a star-shaped cylindrical side wall member 22 ″ provided so that each apex is in contact with the inner wall of the well pipe 3 and provided independently of the pumping pump 6 is used. Furthermore, regarding the bottom member 21 of the pump accommodating portion 7, it may be configured integrally with the bottom plate 10 of the well pipe 3. In this way, the bottom member 21 constitutes the bottom surface of the well pipe 3, so The configuration can be simplified.

  Further, the diameter and depth of the well, the inner diameter of the pump housing portion 7, and the output and size of the pumping pump 6 are merely examples, and are appropriately determined according to the situation at the site.

1 Earth retaining wall 2 Pumping device 3 Well pipe (3a Inflow space)
4 Blocking lid 5 Decompression pump 6 Pumping pump 7 Pump storage (7a storage space)
8 Strainer (8a slit, 8b wire, 8c slit top)
DESCRIPTION OF SYMBOLS 10 Bottom plate 11 Intake pipe 12 Intake port 13 Drain pipe 21 Bottom member 22, 22 'Side wall member (22a Upper end of side wall member)
23 Leg member 32 Deep well (pumped well)
33 Recharge well
G Ground G1 Excavation site G2 Non-excavation site G3 Impermeable layer G4 Clay layer G5 Location to be improved FL Filter W Groundwater (WL1 Water level in the well pipe, WL2 Water level in the ground)

Claims (7)

A strainer is provided at the lower end, a well pipe buried in the ground,
A closing lid for closing the inner space of the well pipe in an airtight state;
A decompression section for decompressing the inner space of the well pipe closed by the closure lid;
Pump housing provided with a cylindrical side wall member whose height is determined so that the upper end is located above the groundwater inflow portion of the strainer, and a bottom member joined in a liquid-tight state to the lower end of the side wall member And
Wherein A in the storage space of the pump housing part, have a, and pumping pump suction port is installed at a position lower than the upper end of the side wall member,
The pumping device according to claim 1, wherein the inflow of water into the storage space is performed by overflowing the side wall member .   The pumping device according to claim 1, wherein the pump housing portion includes a leg member that supports the bottom member in a state of floating from the bottom surface of the well pipe.   The pumping device according to claim 1, wherein a bottom member included in the pump storage portion constitutes a bottom surface of the well pipe.   The soft ground improvement construction method characterized by including the pumping process which pumps up ground water with the pumping apparatus of any one of Claim 1 to 3 installed in the improvement object location in the ground. A retaining wall construction process for constructing a retaining wall at the boundary between the excavation site and the non-excavation site in the ground;
The water pressure lowering step of lowering the groundwater pressure of the groundwater under pressure by the pumping device according to any one of claims 1 to 3 installed in the vicinity of the retaining wall;
A ground excavation process for excavating the excavation site in a state in which lift acting on the excavation site from the lower side is relaxed as the groundwater pressure decreases. A pumping step of installing the pumping device according to any one of claims 1 to 3 on the contaminated soil contaminated with the pollutant, and pumping the groundwater around the contaminated soil containing the pollutant;
A contaminated soil purification method comprising a contaminant treatment step for treating the contaminant in the pumped groundwater on the ground. A condensing step of injecting water into a condensate well provided on the ground and returning the water into the ground;
A condensate method for performing a recovery process for improving clogging around the condensate well by pumping water in the inner space of the condensate well,
A condensate construction method comprising the pumping device according to any one of claims 1 to 3 in the condensate well.