Ground liquefaction preventing structure and method of using the same

Abstract

To provide a liquefaction preventive structure of the ground capable of preventing liquefaction of a wide range by collecting underground water from the wide range of the ground, and its utilization method.SOLUTION: In this liquefaction preventing structure of the ground 2 for preventing liquefaction of the ground 2 by arranging a water collecting well 3 in the ground 2 for holding underground water, pumping up water flowing in the water collecting well 3 by a submerged pump 6 being a pumping means, and lowering an underground water level of the ground 2, a plurality of water collecting wells 3 and 3 are arranged at a predetermined interval, and a plurality of water collecting pipes 4 and 4 arranged in the ground 2 are connected to the respective water collecting wells 3 and 3. Since the underground water flowing into the water collecting well 3 from the water collecting pipe 4 is pumped up by the submerged pump 6, the underground water of the ground 2 is collected in the water collecting well 3 by the water collecting pipe 4, and the underground water collected in the water collecting well 3 is pumped up to prevent liquefaction of the ground 2 in a wide range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ground liquefaction prevention structure and a method for using the same. [Background technology]

[0002] Conventionally, as a water treatment device of this type, there has been a liquefaction prevention method for preventing ground liquefaction, in which a vertical water collector is installed in a liquefaction layer, water that flows into the collector is pumped up by a pumping means, and the groundwater level in the liquefaction layer is lowered to prevent liquefaction. In this method, a pumping control means for controlling the pumping rate of the pumping means and an earthquake motion detection means for detecting earthquake motion are used, and the groundwater in the liquefaction layer is pumped up by the pumping means, and the groundwater level is lowered to a predetermined normal water level, and then the pumping rate of the pumping means is controlled to maintain the normal water level (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-65376 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-mentioned liquefaction prevention structure uses a well equipped with a strainer as a water collector, which can collect groundwater around the well, but is not suitable for collecting groundwater from a wide area of ​​the ground around the well. Another problem is that it cannot be constructed in places where there is no space to dig a well, such as densely populated residential areas. Furthermore, no consideration was given to how the collected groundwater would be used.

[0005] Therefore, an object of the present invention is to provide a ground liquefaction prevention structure that can collect groundwater from a wide area of ​​the ground and prevent liquefaction over a wide area, and a method for using the same. [Means for solving the problem]

[0006] The invention of claim 1 is a ground liquefaction prevention structure that prevents ground liquefaction by arranging a collection well in the ground that holds groundwater, pumping up water that flows into the collection well using a pumping means, and lowering the groundwater level in the ground, characterized in that a plurality of the collection wells are arranged at predetermined intervals, a plurality of collection pipes arranged in the ground are connected to each collection well, and the groundwater that flows into the collection well from the collection pipes is pumped up by the pumping means.

[0007] The invention of claim 2 is characterized in that the plurality of water collection pipes are arranged radially.

[0008] The invention of claim 3 is characterized in that the plurality of water collection pipes are arranged in multiple stages at intervals in the depth direction of the water collection well, and an opening / closing means is provided for opening and closing the base end openings of the water collection pipes.

[0009] The invention of claim 4 is characterized in that the ground liquefaction prevention structure of claim 1 is used, and the pumped groundwater is stored in a reservoir for use.

[0010] The invention of claim 5 is characterized in that the ground liquefaction prevention structure of claim 1 is used and the pumped groundwater is used for air conditioning or heating.

[0011] The invention of claim 6 is characterized in that the groundwater pumped from the collection well is used for cooling or heating, and the used groundwater is returned to another collection well. [Effects of the Invention]

[0012] According to the configuration of claim 1, groundwater in the ground is collected in a collection well by a collection pipe, and the groundwater collected in this collection well is then pumped up, thereby making it possible to prevent ground liquefaction over a wide area.

[0013] According to the configuration of claim 2, groundwater can be efficiently collected by the radially arranged water collection pipes.

[0014] According to the configuration of claim 3, by operating the opening and closing means of the water collection pipes provided in multiple stages, it is possible to adjust the groundwater level so as to prevent liquefaction from occurring.

[0015] According to the configuration of claim 4, excess groundwater stored in the reservoir can be utilized.

[0016] According to the configuration of claim 5, the pumped groundwater can be used for cooling or heating.

[0017] According to the configuration of claim 6, the heat medium can be cooled or heated by the pumped groundwater, and can be used for cooling or heating. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional view showing a first embodiment of the present invention. [Figure 2] Same as above, this is a plan view illustrating the arrangement of the collection wells and collection pipes. [Figure 3] FIG. 10 is a block diagram of the control means. [Figure 4] 4A is a front view of the water collection pipe, FIG. 4B is a cross-sectional view taken along line AA, and FIG. 4C is a cross-sectional view taken along line BB. [Figure 5] Same as above, cross section of the observation well. [Figure 6] FIG. 4 is a cross-sectional view showing a second embodiment of the present invention. [Figure 7] FIG. 10 is a front view illustrating a water treatment device according to a third embodiment of the present invention. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. [Figure 14]FIG. 1 is a plan view of the stirring blade with a portion thereof in cross section. [Figure 15] FIG. [Figure 16] FIG. 10 is a perspective view of the main part of the landing tank. [Figure 17] FIG. 10 is a plan view of the water receiving tank and separation tank. [Figure 18] FIG. 10 is an explanatory plan view of a water receiving tank and a separation tank according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the embodiments described below do not limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential requirements of the present invention. In each example, a new ground liquefaction prevention structure and a method of using it that are different from conventional structures are adopted, resulting in a ground liquefaction prevention structure that has not been seen before and a method of using it. This ground liquefaction prevention structure and a method of using it will be described. [Example]

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figures 1 to 5 show embodiment 1 of the present invention, and as shown in the figures, a ground liquefaction prevention structure 1 of the present invention has vertical collection wells 3, which are shafts, installed at intervals in ground 2 that holds groundwater, and a plurality of collection pipes 4 installed radially in the horizontal direction in the collection wells 3, and the base ends of the collection pipes 4 are connected to the collection wells 3.

[0021] The water collection pipe 4 has a base end opening 5, which is the pipe end on the base side, located on the water collection well 3 side, and water can be pumped out of the water collection well 3 by a submersible pump 6, which is a pumping means installed at the bottom of the water collection well 3. Note that buildings such as houses 7 and buildings 8 are installed on the ground above the ground 2. The liquefaction prevention structure 1 in this example is installed on the ground 2 close to a river 9.

[0022] The collection well 3 comprises a cylindrical body 11, a bottom surface 12 that closes the bottom of the body 11, and an upper surface 13 that closes the upper opening 11K of the body 11, and is made of concrete, a liner plate, or the like. The submersible pump 6, which serves as a pumping means, is disposed on top of the bottom surface 12, and a water supply pipe 15 connected to the submersible pump 6 passes through the upper surface 13 and extends to the ground. In addition, an open / close lid (not shown) for inspection can be provided on the upper surface 13.

[0023] The water collection pipes 4 are arranged in multiple stages at intervals in the depth direction of the collection well 3, with the upper stage water collection pipe 4, the middle stage water collection pipe 4, and the lower stage water collection pipe 4 arranged from top to bottom. As shown in Figure 2, the water collection pipes 4 are arranged radially at equal intervals in the circumferential direction around the collection well 3. Each collection well 3 is provided with a plurality of the water collection pipes 4 arranged in the ground 2, and the base end openings 5 ​​of the plurality of water collection pipes 4 are positioned so as to communicate with the collection well 3 side, so that groundwater that flows into the collection well 3 from the base end openings 5 ​​of the water collection pipes 4 is pumped up by the submersible pump 6.

[0024] An on-off valve 16 serving as on-off means is connected to the base end opening 5 of the water collection pipe 4 and is located inside the water collection well 3. This on-off valve 16 is an electrically operated valve, to which a cable 17 is connected that supplies power and transmits a drive signal, and this cable 17 passes through the top surface portion 13, extends to the ground, and is electrically connected to control means 31 equipped with a power source.

[0025] As shown in Figure 2, the collection wells 3 are arranged in a grid pattern at equal intervals in the front-to-back and left-to-right directions, and the interval between adjacent collection wells 3, 3 in the front-to-back and left-to-right directions is, for example, about 100 m (meters). Each collection well 3 has a depth of about 10 to 11 m (10 m or more and 11 m or less) and an inner diameter of 3 to 4 m. Approximately 10 to 20 collection pipes 4 are connected to one collection well 3, and the length from the center of the collection well 3 to the tip of the collection pipe 4 is about 50 m. The length of the collection pipe 4 is about half the interval between adjacent collection wells 3, 3.

[0026] In constructing the water collection pipes 4, horizontal holes (not shown) for inserting the water collection pipes 4 are bored in the ground 2, and the water collection pipes 4, which are divided in the longitudinal direction, are inserted into the horizontal holes from inside the water collection well 3 and connected for construction. Alternatively, multiple steel pipes with straight threads can be used for the water collection pipes 4, with a drilling blade attached to the tip of the steel pipe at the end, and the steel pipes can be inserted into the ground 2 while being rotated, and the multiple steel pipes can be connected with straight threads for construction.

[0027] By arranging multiple collection pipes 4 horizontally from the collection well 3 in this way, groundwater from the ground 2 beneath the existing house 7 can be drained over a wide area, preventing liquefaction of the ground 2 beneath the existing house 7 and other structures.

[0028] The water collection pipe 4 is a perforated pipe made of a rigid polyvinyl chloride pipe or a steel pipe with a nominal diameter of 40A to 50A, and is provided with a plurality of water collection holes 4A, 4B with diameters of 6 to 8 mm (millimeters). For example, as shown in Fig. 4, four water collection holes 4A, 4A, 4A, 4A are provided at equal intervals around the circumference of the water collection pipe 4, and adjacent water collection holes 4B, 4B, 4B, 4B along the length of the water collection pipe 4 are offset by 45 degrees around the circumference at predetermined intervals of, for example, about 100 mm, so that the water collection hole 4B is located between the water collection holes 4A, 4A. The water collection holes 4A, 4B, 4A, 4B, ... are provided at different circumferential positions along the length of the water collection pipe 4 at the predetermined intervals. The water collection holes 4A, 4B are not shown in any drawings other than Fig. 4.

[0029] In addition, a gutter 21 and a reservoir 22 are provided on the ground surface of the ground 2, and the water supply pipes 15 of each collection well 3, 3... are connected to a drainage water supply pipe 23 that sends groundwater to the gutter 21 and a water storage water supply pipe 24 that sends groundwater to the reservoir 22, and these water supply pipes 23, 24 are provided with opening and closing valves 23A, 24A as opening and closing means.

[0030] The on-off valves 23A, 24A are electrically operated valves, and are connected to cables 17A, 17B that supply power and transmit drive signals, and these cables 17A, 17B are electrically connected to the control means 31. The on-off valves 16, 23A, 24A have adjustable openings. The submersible pump 6 is connected to a cable 17C that supplies power and transmits drive signals, and this cable 17C is electrically connected to the control means 31.

[0031] Furthermore, as shown in Figure 5, the ground 2 in which the collection well 3 is provided has multiple test wells 41, 41A, 41B, which are vertical shafts. In this example, the test wells 41, 41A, 41B have depths corresponding to the depths of the upper, middle, and lower collection pipes 4, 4, 4, and the cylindrical bodies of these test wells 41, 41A, 41B have multiple collection holes (not shown), from which groundwater flows into the interior.

[0032] In addition, submersible pumps 42, 42A, 42B are provided in each test well 41, 41A, 41B as pumping means, and the groundwater in the test wells 41, 41A, 41B is pumped up through pipelines 43, 43A, 43B connected to the submersible pumps 42, 42A, 42B, and the water content of the ground 2 can be determined by conducting a pumping test to observe the groundwater.

[0033] In the above-described liquefaction prevention structure 1, the on-off valve 16 is normally opened by the required amount under the control of the control means 31, and the groundwater that has passed through the water collection hole 4A and accumulated in the water collection pipe 4 can be stored in the water collection well 3 through the on-off valve 16 provided at the base end opening 5. By adjusting the opening of the on-off valve 16 in this way, it is possible to adjust the water level in the ground 2 and the amount of water contained in the ground 2. The opening of the on-off valve 16 is set based on the results of a pumping test so that the ground 2 has a predetermined water level and moisture content. This makes it possible to prevent more groundwater than necessary from being drained, which could lead to land subsidence.

[0034] The groundwater that has accumulated in the collection well 3 is sent to the reservoir 22 by the submersible pump 6 and stored there, and excess groundwater is discharged into the street gutter 21. The groundwater that has accumulated in the reservoir 22 can also be used for fire prevention, etc. Furthermore, since the temperature of groundwater remains almost constant all year round, it can be used to cool road surfaces in the evening in summer and to melt snow in winter.

[0035] When the groundwater level in the ground 2 rises due to heavy rainfall or the like, the necessary on-off valve 16 is opened, the groundwater in the ground 2 is collected in the collection well 3, and the groundwater is then drained into a gutter 21 or the like, thereby lowering the groundwater level and adjusting the moisture contained in the ground 2, thereby preventing liquefaction of the ground 2.

[0036] In this embodiment, corresponding to claim 1, a collection well 3 is placed in the ground 2 that holds groundwater, and water that flows into the collection well 3 is pumped up by a submersible pump 6 as a pumping means, thereby lowering the groundwater level in the ground 2 and preventing liquefaction of the ground 2. In this liquefaction prevention structure 1 for ground 2, a plurality of collection wells 3,3 are placed at predetermined intervals, and a plurality of collection pipes 4,4 placed in the ground 2 are connected to each collection well 3,3, and groundwater that flows from the collection pipes 4 into the collection well 3 is pumped up by the submersible pump 6.Therefore, by collecting the groundwater in the ground 2 in the collection well 3 by the collection pipe 4 and pumping up the groundwater collected in this collection well 3, liquefaction of the ground 2 can be prevented over a wide area.

[0037] As described above, in this embodiment, in accordance with claim 2, the plurality of water collection pipes 4, 4 are arranged radially, so that groundwater can be collected efficiently.

[0038] In this way, in this embodiment, corresponding to claim 3, a plurality of water collection pipes 4, 4, 4 are arranged in multiple stages at intervals in the depth direction of the water collection well 3, and an on-off valve 16 is provided as an on-off means for opening and closing the base end opening 5 of the water collection pipe 4.Therefore, by operating the on-off valve 16 of the water collection pipes 4 arranged in multiple stages, the groundwater level can be adjusted so that liquefaction does not occur.

[0039] In this way, in this embodiment, in accordance with claim 4, the ground liquefaction prevention structure 1 described in claim 1 is used, and the pumped groundwater is stored in the reservoir 22 for use, so that the excess groundwater stored in the reservoir 22 can be utilized.

[0040] As an effect of the embodiment, test wells 41, 41A, 41B having depths corresponding to the depths of the upper, middle, and lower water collection pipes 4, 4, 4 are provided, and submersible pumps 42, 42A, 42B, which are pumping means and pressure transfer means, are provided in each test well 41, 41A, 41B, and groundwater in the test wells 41, 41A, 41B is pumped up by pipelines 43, 43A, 43B connected to the submersible pumps 42, 42A, 42B, and the water content of the ground 2 can be determined by conducting a pumping test to observe the groundwater.

[0041] Also, since the collection pipes 4, 4... are arranged radially from the collection well 3, it is possible to prevent liquefaction over a wide area by excavating the collection well 3 at a location away from the houses 7 and buildings 8 and placing the collection pipes 4 in the ground 2 beneath the existing houses 7 and buildings 8. Furthermore, since between 10 and 20 collection pipes 4 are connected to one collection well 3 and the included angle between adjacent collection pipes 4, 4 is constant, it is possible to collect groundwater evenly from the ground 2 and store it in the collection well 3.

[0042] Furthermore, the collection wells 3, 3... are arranged in a grid pattern at equal intervals in the front, back, left and right directions, and the distance between the centers of the collection wells 3, 3 is between 1.8 and 2 times the length (42 to 62 m) from the center of the collection well 3 to the tip of the collection pipe 4. Therefore, the tips of the collection pipes 4, 4 of adjacent collection wells 3, 3 are close to each other, and groundwater can be collected from a wide area of ​​the ground 2. [Example]

[0043] FIG. 6 shows a second embodiment of the present invention, in which the same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

[0044] In this example, one of the collection wells 3, 3... close to the house 7 is used as a pumping well 51, and the remaining multiple collection wells 3 are used as reinjection wells 52, and the groundwater pumped from the pumping well 51 is used to cool or heat the heat medium in heat exchangers such as heat pump air conditioners and radiators. In this way, there are more reinjection wells 52 than there are pumping wells 51. The groundwater after heat exchange may be drained into the side gutter 21.

[0045] The pumping well 51 and the reinjection well 52 are connected by a pipeline 53, and a pump 54 serving as a pressure transfer means is provided in this pipeline 53. A heat pump (outdoor unit) 57 of an air conditioner 55 connected to a fan coil (indoor unit) 56 of the air conditioner 55 in the house 7 is provided in the pipeline 53, so that pumping and reinjection can be carried out continuously, and the air conditioner 55 can be switched between cooling and heating.

[0046] By using groundwater to cool or heat the heat pump's heat medium in this way, it is possible to save on electricity costs for heating and cooling.

[0047] In this way, the present embodiment provides the same functions and effects as the first embodiment.

[0048] In this way, in this embodiment, in accordance with claim 5, the liquefaction prevention structure 1 for the ground 2 described in claim 1 is used, and the pumped groundwater is used for air conditioning or heating, so that the pumped groundwater can be used for air conditioning or heating.

[0049] In this way, in this embodiment, corresponding to claim 6, the groundwater pumped from the collection well 3 is used for air conditioning or heating, and after use, the groundwater is returned to another collection well 3, so that the pumped groundwater can be used to cool or heat the heat medium, thereby making it possible to use it for air conditioning or heating. [Example]

[0050] Figures 7 to 18 show a third embodiment of the present invention, in which the same parts as those in the above-mentioned embodiments are given the same symbols and detailed explanations thereof are omitted. In this embodiment, a water treatment device 101 is used to purify groundwater pumped from a collection well 3.

[0051] The water treatment device 101 includes a receiving tank 103, which is a receiving well that stores groundwater 102, which is raw water obtained from the collection well 3; a stirring tank 105 that receives the groundwater 102 from the receiving tank 103 and stirs water to be treated 104, which is groundwater 102 to which a coagulant and a bactericide have been added; a receiving tank 107 that stores the water to be treated 104, which is a mixture of groundwater 102, a coagulant, and a bactericide, and in which flocs 106 are formed; and a separation tank 108 to which the water to be treated 104 containing the flocs 106 from the receiving tank 107 is sent and in which the flocs 106 settle and are separated.

[0052] The groundwater 102 in the reservoir 22 is sent to the receiving tank 103 via a sand pump 111, which serves as a pressure-transfer means provided in the reservoir 22, and a pipeline 112 that connects the sand pump 111 and the receiving tank 103. The receiving tank 103 is also provided with a water level sensor 113 that detects the level of the groundwater 102 therein, and when the level of the groundwater 102 reaches a predetermined height, a control means 114 (FIG. 8) stops the sand pump 111. The groundwater 102 accumulated in the collection well 3 may be configured to be sent to the receiving tank 103 via a pressure-transfer means and pipeline 112 (not shown).

[0053] 8 is a front view, and the water receiving tank 107 is formed in a generally rectangular shape in plan view and long in the left-right direction so as to be suitable for transportation by helicopter or for loading onto the bed of a transport vehicle such as a truck. The water landing tank 103, like the separation tank described below, is also formed in a generally rectangular shape in plan view and long in the left-right direction, but is shorter in the left-right direction than the water receiving tank 107.

[0054] The water reservoir 103 has a front surface 122, a rear surface 123, and left and right side surfaces 124L, 124R on all four sides of a plate-shaped bottom surface 121, and has a connection portion 125 at the top of one of the left and right side surfaces 124L to detachably connect the pipe line 112. In addition, an upper lid 126 that closes the water reservoir 103 is provided at the top of the water reservoir 103.

[0055] The agitation tank 105 has a front surface 132, a rear surface 133, and left and right side surfaces 134L, 134R on all four sides of a plate-shaped bottom surface 131; its left-right width is less than one-third that of the water-receiving tank 107, and it is longer in the front-to-back direction than in the left-to-right direction. It has a top surface 135 at its top, and an upper opening 135K on the other left-to-right side of the top, and is located on the right side of the water-receiving tank 107. A middle frame 136 is provided on the left side of the agitation tank 105, and this frame 136 is made of steel such as angle iron arranged in a frame shape. The agitation tank 105 and the frame 136 integrally formed with the agitation tank 105 constitute an agitation tank unit 137.

[0056] The water receiving tank 107 has a front surface 142, a rear surface 143, and left and right side surfaces 144L, 144R on all four sides of a plate-shaped bottom surface 141, and has an upper opening 145 at the top. As shown in Figure 10, the bottom surface 141 of the water receiving tank 107 is provided with an inclined bottom panel 146 that is inclined so that it slopes downward toward one side in the left-right direction on the other side in the left-right direction. The angle of the inclined bottom panel 146 with respect to the horizontal is between 15 degrees and 30 degrees, and is at least half the length of the interior of the water receiving tank 107 in the left-right direction (the distance between the inner surfaces of the side surfaces 144L, 144R).

[0057] Furthermore, on the left side of the bottom surface 141 of the water tank 107 in the left-right direction, a flat rectangular bottom surface recess 147 is formed which is one step lower than the bottom surface 141, and on the other left-right side of this bottom surface recess 147, an inclined surface 148 is formed which slopes downward toward the bottom surface recess 147 on one side, and in front and behind the bottom surface recess 147, front and rear inclined surfaces 149, 149 are provided which slope downward toward the central bottom surface recess 147.

[0058] An upper flange 151 is provided around the upper opening 145 of the water tank 107, and through holes 151T are drilled in this upper flange 151. A plurality of hoisting devices 152 are fixed to the inner surfaces of the upper portions of the front and rear surfaces 142 and 143, and these hoisting devices 152 are drilled with receiving holes 152T for attaching hooks (not shown) attached to lifting cables. Fig. 8 shows a hoisting device 152 in which receiving holes 152T are drilled in a plate, and Fig. 13 shows a modified hoisting device 152A in which receiving holes 152T are formed by forming a rod into a substantially inverted U shape.

[0059] Furthermore, as shown in Figure 8, a plurality of support legs 138 are provided at the bottom of the agitation vessel unit 137, protruding downward on the front, back, left and right sides. At the lower ends of these support legs 138, horizontal plate-shaped mounting portions 139 are provided to be placed on the upper flange portion 151. Through holes 139T are bored in this mounting portion 139 corresponding to the through holes 151T of the upper flange portion 151.

[0060] Therefore, a hook can be engaged with the hoisting tool 152, and the water-receiving tank 107 can be lowered by the rope. The agitation tank unit 137 can be placed on top of the water-receiving tank 107 by overlapping the upper flange 151 of the water-receiving tank 107 with the placement part 139, inserting bolts 153 through the through-holes 151T and 139T of both tanks, and screwing nuts 154 onto the bolts 153. Conversely, the agitation tank 105 can be assembled on top of the water-receiving tank 107 by removing the bolts 153 and nuts 154. The upper flange 151, support legs 138, bolts 153, and nuts 154 thus constitute an assembly / disassembly means 155 that enables the water-receiving tank 107 and agitation tank unit 137 to be assembled and disassembled in the overlapping state, and reference numeral 156 denotes the separation point.

[0061] 8, an upper flange 161 with through holes 161T is provided around the upper end of agitation vessel unit 137, and a plurality of hangers 152 with receiving holes 152T are fixed thereto, and a lower flange 163 with through holes 163T is provided around the lower end of water receiving vessel 103. A plurality of hangers 152 are fixed to the upper end of water receiving vessel 103.

[0062] Then, bolts 153 are inserted into holes 161T and 163T, and nuts 154 are screwed onto these bolts 153, thereby enabling the deposition tank 103 to be assembled and disassembled on the agitation tank unit 137. In this way, the upper flange 161, the lower flange 163, the bolts, and the nuts constitute an assembly / disassembly means 165 that allows the agitation tank 105 and the deposition tank 103 to be assembled and disassembled when they are stacked together, and reference numeral 166 indicates the separation point.

[0063] When the reservoir 103 is stacked on top of the agitation tank unit 137 and assembled, a reservoir-side outlet 171 for discharging the groundwater 102 in the reservoir 103 into the agitation tank 105 is provided on the lower side of the other side surface 124R in the left-right direction of the reservoir 103. Also provided is an opening / closing means 172 for opening and closing the outlet 171.

[0064] This opening / closing means 172 comprises a lid body 173, a gasket material 174 (Fig. 7) provided on the inner surface of this lid body 173 and abutting against the outer surface of the side portion 124L around the discharge port 171 to close the discharge port 171, and as shown in Fig. 13, an extendable drive shaft 176 of a fluid pressure cylinder 175 serving as a drive means pivotally attached to the lid body 173, guide members 177, 177 arranged on both sides of the fluid pressure cylinder 175, and a suspension structure 178 for suspending the lid body 173.

[0065] As shown in Figure 13, a mounting seat 181 is provided on the upper surface 135 of the stirring tank 105, and the main body 175H of the fluid pressure cylinder 175 is fixed to the center of this mounting seat 181. A U-shaped connecting portion 182 is provided on the tip of the telescopic drive shaft 176, and a connecting piece 183 that connects this connecting portion 182 protrudes from the center of the width direction of the outer surface of the lid body 173. A through hole (not shown) is formed in the connecting piece 183, and corresponding through holes (not shown) are formed in a pair of arms of the connecting portion 182. A connecting pin 184 is inserted into the through holes in the pair of arms of the connecting portion 182 and the through hole in the connecting piece 183, thereby rotatably connecting the tip of the telescopic drive shaft 176 to the lid body 173.

[0066] The guide member 177 fixes a guide tube 190 to the mounting seat 181, and a guide rod 191 is movably inserted into the guide tube 190. A U-shaped connecting portion 192 is provided at the tip of the guide rod 191, and connecting pieces 193, 193 that connect the connecting portion 192 protrude from both sides of the outer surface of the lid body 173 in the width direction. A through hole (not shown) is formed in the connecting piece 193, and corresponding through holes (not shown) are formed in a pair of arms of the connecting portion 192. A connecting pin 194 is inserted into the through holes in the pair of arms of the connecting portion 192 and the through hole in the connecting piece 193, thereby rotatably connecting the tip of the guide rod 191 to the lid body 173. The connecting portions 192, 182, 192 protrude from the outer surface of the lid body 173 at approximately the same height.

[0067] On the outer surface of the side portion 134L, at the center of the upper part of the discharge outlet 171, a support rail 201 which is a support member constituting part of the hanging structure 178 is protruded in a direction intersecting with the discharge outlet 171, this support rail 201 is in the shape of a plate, and an upper edge portion 202 is formed so as to be slightly lower toward the tip side, and a stopper portion 203 which protrudes upward is provided at the tip of this upper edge portion 202.

[0068] A hanging member 205 that is hung on the support rail 201 is provided at the center of the outer surface of the upper part of the lid body 173, and this hanging member 205 constitutes a part of the hanging structure 178. The hanging member 205 has a base end fixed to the center of the outer surface of the upper part of the lid body 173, and is equipped with a pair of arms 206, 206 that are arranged to sandwich the support rail 201, and a wheel 207 that is arranged at the upper part of these approximately L-shaped arms 206, 206 and sandwiched between the arms 206, 206, and this wheel 207 is rotatably attached to the arms 206, 206 by a rotation shaft 208, and the wheel 207 rolls on the upper edge portion 202.

[0069] Moreover, a pressurizing device 210 (Fig. 8) constituting a part of the opening and closing means 172 is provided above the stirring tank 105, and as shown in Fig. 9, a fluid such as oil is contained in a pressurizing cylinder 211 of the pressurizing device 210, and the pressurizing cylinder 211 and the fluid pressure cylinder 175 are suspended by a pipe 212. A pressurizing handle 213 is pivotally attached to the pressurizing device 210, and by repeatedly rotating the handle 213, the fluid in the pressurizing cylinder 211 is pressurized and sent under pressure to the fluid pressure cylinder 175. Incidentally, Fig. 9 shows a pressurizing device 210A having the same configuration as the pressurizing device 210, provided on a frame 136.

[0070] The pressurizing device 210 is also provided with a knob 214 that serves as a pressure reduction operation section for reducing the fluid pressure in the pressurizing cylinder 211. When the knob 214 is turned in one direction, the fluid pressure in the pressurizing cylinder 211 can be reduced, and when the knob 214 is turned in the other direction, the pressurizing fluid (not shown) in the pressurizing cylinder 211 can be pressurized by operating the handle 213, and the pressurized fluid can be sent to the fluid pressure cylinder 175 through the pipe 212.

[0071] When the fluid in the pressurizing cylinder 211 is pressurized by the pressure device 210 and pumped to the fluid pressure cylinder 175, the lid 173 moves forward toward the discharge port 171, and the discharge port 171 is closed by the lid 173 and maintained in a closed state.

[0072] When the pressure inside the pressurizing cylinder 211 is reduced by operating the knob 214, the pressure of the fluid inside the fluid pressure cylinder 175, which has a higher pressure than the pressure inside the pressurizing cylinder 211, drops, and the lid 173 moves back. Specifically, when the lid 173 is in the closed state shown in Figure 13, the weight of the lid 173 is applied to the support rail 201 via the wheels 207, and the lid 173 is held vertically and is pushed by the fluid pressure cylinder 175, so that the discharge port 171 can be reliably closed by the lid 173.

[0073] When the telescopic drive shaft 176 is retracted from this closed state, the lid body 173 is retracted in a direction away from the discharge port 171, and the wheels 207 roll on the upper edge portion 202 that slopes downward toward the tip, and the lid body 173 is suspended by the wheels 207, so that the upper edge side of the lid body 173 tilts forward, as shown in Figure 7, and some of the groundwater 102 discharged from the discharge port 171 hits the inner surface of the lid body 173 and falls into the mixing tank 105 below. In addition, the wheels 207 are locked by the stoppers 203, so that the wheels 207 do not come off the support rails 201.

[0074] When the agitation tank unit 37 is stacked on top of the water receiving tank 107 and assembled, an agitation tank-side discharge port 171A, which discharges the water to be treated 104 in the agitation tank 105 from the upper opening 145 of the water receiving tank 107 into the water receiving tank 107, is provided on the lower side of one of the side surfaces 34L in the left-right direction of the agitation tank 105. The opening / closing means 172A for opening and closing the discharge port 171A is also provided, and the components of this opening / closing means 172A are the same as those of the opening / closing means 172, although the mounting positions of some of the components are different.

[0075] Specifically, as shown in Figures 7 and 8, discharge outlet 171A is opened and closed by lid body 173A, which has the same configuration as lid body 173, and connecting portions 182, 192, 192 are rotatably connected to lid body 173A, and fluid pressure cylinder 175 and guide tube 190 are fixed within frame body 136 of mixing vessel unit 137.

[0076] Furthermore, on the outer surface of the side portion 34L, the support rail 201 protrudes from the upper center of the discharge outlet 171A, the hanging member 205 is provided on the upper part of the lid body 173A, and a pressure device 210A having the same configuration as the pressure device 210 is attached to the upper part of the frame body 36, and the pressure device 210A and a fluid pressure cylinder 175 are connected by a pipe 212, and the lid body 173A that opens and closes the discharge outlet 171A is opened and closed in the same way as the lid body 173 that opens and closes the discharge outlet 171A.

[0077] Therefore, by operating the pressure device 210, the lid 173A of the opening / closing means 172 can be moved toward the discharge outlet 171A, and the discharge outlet 171A can be blocked by the lid 173A. When the lid 173A is moved toward the opposite side of the discharge outlet by the opening / closing means 172, the discharge outlet 171A opens, and the treated water 104 in the stirring tank 105 can be supplied to the receiving tank 107.

[0078] In this case, since the inclined bottom plate portion 146 is located below the discharge port 171A, the flocs 106 contained in the water to be treated 104 can be guided toward the bottom recess 147. Moreover, the bottom recess 147 has an inclined surface 148 that slopes in the same direction as the inclined bottom plate portion 146 and slopes downward toward the bottom recess 147. In addition, front and rear inclined surfaces 149, 149 that slope downward toward the bottom recess 147 are provided at the front and rear of the bottom recess 147, respectively. Therefore, the flocs 106 gather at the suction port 232 of the sand pump 231, which serves as a pumping means and is disposed at the bottom recess 147, and the water to be treated 104 containing the flocs 106 can be reliably sucked in.

[0079] An agitator blade 221 serving as an agitator is provided within the agitation tank 105. The agitator blade 221 has a horizontal rotation shaft 222 that is long in the front-to-rear direction, and a pair of roughly rectangular, flat agitator plates 223, 223 are provided on the rotation shaft 222. Furthermore, reinforcing ribs 223R, 223R are attached to the inner and outer surfaces of the agitator plates 223, 223 in the width direction at the center of the length of the agitator plates 223, 223.

[0080] Furthermore, the agitator blade 223 has a plurality of equally spaced through-holes 224 arranged in a staggered pattern such that one row of the through-holes 224 is positioned midway between the adjacent rows of through-holes 224. The diameter of the through-holes 224 is 30 mm, preferably 20 mm to 40 mm. If the through-holes 224 are too small, the resistance during rotation increases, while if the through-holes 224 are too large, the agitation effect decreases. However, by setting the size, the rotation resistance is reduced, and an agitator blade 221 with high agitation effect can be obtained.

[0081] A connecting flange 225 is provided at the end of the rotating shaft 222, and a notch 226 is formed at the end of the agitating plate 223 to accommodate the flange 225. Bearings 227 are provided on the front and rear surfaces 142 and 143, respectively. A connecting shaft 228 is rotatably supported by the bearings 227 and has a shaft-side flange 229. The shaft-side flange 229 and the flange 225 are connected with bolts and nuts. An electric motor 230 (FIG. 8) with a reducer is provided on the top surface 35 of the agitating tank 105 as a rotation drive means. The rotation of the electric motor 230 is transmitted to the connecting shaft 228, causing the agitating blade 221 to rotate forward and backward. The electric motor 230 is driven by a generator.

[0082] Then, an operator pours a flocculant and a disinfectant into the upper opening 35K, and drives the electric motor 230 to rotate the stirring blades 221, thereby stirring the water to be treated 104. In this case, these operations can be performed automatically or semi-automatically.

[0083] As shown in Figure 7, a sand pump 231 is provided to suck the water to be treated 104 from the water receiving tank 107, and this sand pump 231 is arranged so that its suction port 232 is located in the bottom recess 147 of the water receiving tank 107, and the water to be treated 104 sucked by the sand pump 231 is sent to the separation tank 108 through a pipeline 233.

[0084] Then, multiple (e.g., about 3 to 8) separation tanks 108 are placed near the location where groundwater 102 is obtained. These separation tanks 108 are box-shaped with a bottom and an open top, and have a front surface, a rear surface, left and right side surfaces, and an upper opening on all four sides of the plate-like bottom. Like the landing tank 103, the mixing tank unit 37, and the water receiving tank 107, they can be transported by being loaded onto the carrier of a helicopter or truck. Preferably, all of the settling tanks are provided with a sand pump 231A as a pumping means for sucking settled flocs 106 and a sand pump 231B as a pumping means for sucking supernatant water 109.

[0085] A plurality of separation tanks 108, 108, etc. are arranged in close proximity, and the pipeline 233 includes an upstream pipeline 235 between the sand pump 231 and an on-off valve 234 provided outside the water receiving tank 107, and a flexible downstream pipeline 236 made of a flexible pipe with a bellows structure or the like connected downstream of the on-off valve 234.

[0086] Therefore, the discharge port 237 of the downstream pipe 236 is connected to one separation tank 108, that is, the discharge port 237 is positioned so that the water to be treated 104 is sent from the discharge port 237 to the separation tank 108, and with the on-off valve 234 open, the sand pump 231 is driven to send the water to be treated 104 from the water receiving tank 107 to the separation tank 108. When the water to be treated 104 in the separation tank 108 becomes full, the on-off valve 234 is closed. Thereafter, the discharge port 237 is connected to another empty separation tank 108, and the water to be treated 104 is sent to that empty separation tank 108 in the same manner. When the separation tank 108 becomes full, the water to be treated 104 is sent to the next separation tank 108. In the same manner, the discharge port 237 is connected to yet another empty separation tank 108.

[0087] By using multiple separation tanks 108 in this way, even if one separation tank 108 becomes full, the water to be treated 104 in the receiving tank 107 can be continuously discharged with little waiting time, and water treatment can be carried out continuously and efficiently on site using the receiving tank 103, mixing tank 105, and receiving tank 107.

[0088] As shown in FIG. 7, the flocs 106 containing moisture are sucked from the separation tank 108 by the sand pump 231A and packed into a flexible container bag (hereinafter referred to as a flexcon bag), which is a cylindrical bag with an open top and a closed bottom, called a 1-ton bag, and are allowed to naturally dehydrate on-site. The dehydrated cake obtained after dehydration is used as cultivation soil for plants, etc.

[0089] The top water 109 from the separation tank 108 is stored in a clean water tank 241 and used for daily use such as washing, bathing, etc. The top water 109 stored in the other clean water tank 241 is filtered by a filter 242 or the like to make it drinkable.

[0090] In this way, the water treatment device 101 can produce drinking water or water for daily use from the groundwater 102 in the event of a disaster, etc. Also, under normal circumstances, the groundwater 102 can be purified and used as swimming pool water.

[0091] Next, a method of using the water treatment device 101 will be described. The water treatment device 101 is transported to an area where water supply through a water pipe is no longer possible. If roads are available, the water treatment device main body 200, which is an assembly of the receiving tank 103, the mixing tank unit 37, and the receiving tank 107, is transported on the back of a truck or the like. The left-right direction of the water treatment device main body 200 is one lateral direction (length direction), and the front-rear direction intersecting this one lateral direction is the other lateral direction (width direction) of the water treatment device main body 200.

[0092] On the other hand, in an emergency when roads are unusable, the landing tank 103, mixing tank unit 37, and receiving tank 107 are transported individually by helicopter in disassembled state to the site, and the assembled unit is assembled on site. In this case, the assembly / disassembly means 155, 165 overlaps each tank and uses bolts 153 and nuts 154d, making the assembly / disassembly work easy. The separation tank 108 is also transported to the site by truck or helicopter.

[0093] Furthermore, a pipeline 112 is connected to the connection part 125, and a sand pump 111 is disposed in the reservoir 22 or the collection well 3. Furthermore, as shown in Fig. 17, a plurality of separation tanks 108, 108... are disposed, and the water receiving tank 107 and the separation tank 108 are connected by a pipeline 233. The sand pump 111, the pipeline 233 equipped with a downstream pipeline 236 made of a flexible pipe or the like, an on-off valve 234, and the like constitute a pressure-transfer selection means 238 that selectively pressure-transfers the water to be treated 104 in the water receiving tank 107 to the plurality of separation tanks 108, 108...

[0094] The sand pump 111 is driven to send groundwater 102 to the receiving tank 103, and when the water level in the receiving tank 103 reaches a predetermined height, the sand pump 111 is stopped under the control of the control means 114. Then, the discharge port 171 is opened, and the groundwater 102 in the receiving tank 103 is dropped into the mixing tank 105. When the water level in the mixing tank 105 reaches a predetermined height, the discharge port 171 is manually closed, and a flocculant and a disinfectant are added. Then, the electric motor 230 is driven, and the mixing blades 221 rotate, producing water to be treated 104 in which the groundwater 102, the flocculant, and the disinfectant are mixed, and flocs 106 are generated in the water to be treated 104. After the discharge port 171 is closed, the sand pump 111 is driven to resume sending the groundwater 102 to the receiving tank 103.

[0095] The lid 173A is opened to drop and supply almost the entire amount of the water to be treated 104 mixed and stirred in the stirring tank 105 into the water receiving tank 107. The dropped water to be treated 104 moves together with the flocs 106 toward the bottom recess 147 by the inclined bottom plate 146, and is sent to the separation tank 108 by the sand pump 231. In the separation tank 108, the water to be treated 104 is separated into supernatant water 109 and flocs 106. Then, the supernatant water 109 and flocs 106 can be used as described above.

[0096] As described above, in this embodiment, the water treatment device 101 that purifies groundwater 102 obtained from the collection well 3 includes the receiving tank 103 that stores the groundwater 102, the stirring tank 105 that mixes the groundwater 102 sent to the receiving tank 103 with a coagulant, the receiving tank 107 to which the groundwater 102 mixed with the coagulant is sent and the to-be-treated water 104 is formed with flocs 106, and the separating tank 108 to which the to-be-treated water 104 containing the flocs 106 is sent and the flocs 106 settle and are separated. Since the receiving tank 103, the stirring tank 105, and the receiving tank 107 are assembleable and disassembleable, the device can be transported to the site in a disassembled state and assembled for use. This allows the individual tanks to be transported by helicopter, etc., and the individual tanks can be made relatively larger than a single unit, resulting in a water treatment device 101 with high treatment capacity.

[0097] In addition, in this embodiment, the mixing tank 105 is detachably stacked on the receiving tank 107, and the receiving tank 103 is detachably stacked on the mixing tank 105. A receiving tank-side outlet 171 is provided to drop the treated water 104 inside the receiving tank 103 into the mixing tank 105, and an opening / closing means 172 is provided to open and close this receiving tank-side outlet 171. A mixing tank-side outlet 171A is provided to drop the treated water 104 inside the mixing tank 105 into the receiving tank 107, and an opening / closing means 172 is provided to open and close this mixing tank-side outlet 171A. Therefore, by stacking the receiving tank 103, mixing tank 105, and receiving tank 107, the system can be installed with relatively little space, and the treated water 104 can be sent to the tank below by opening and closing the outlets 171, 171A without using a pump or the like.

[0098] Furthermore, in this embodiment, a plurality of separation tanks 108, 108 are provided, and a pressure transfer selection means 238 is provided which selectively pressure transfers the water to be treated 104 in the water receiving tank 107 to the plurality of separation tanks 108, 108. Therefore, when the separation tank 108 becomes full with the water to be treated 104, the pressure transfer selection means 238 can select an empty separation tank 108 and pressure transfer the water to be treated 104. Since the water to be treated 104 in the water receiving tank 107 can be discharged almost continuously, the treatment time can be shortened.

[0099] In this embodiment, the bottom surface 141 of the water-receiving tank 107 is provided with an inclined bottom plate 146, which is an inclined bottom portion having an inclination that decreases toward one side in the lengthwise direction of the water-receiving tank 107, below the agitation tank-side discharge port 171A. One side of the inclined bottom plate 146 of the bottom surface 141 is provided with a bottom recess 147 that is lower than the bottom surface 141. A sand pump 231, which is a pumping means for sucking and discharging the water to be treated 104 in the water-receiving tank 107, is disposed in this bottom recess 147. Since the inclined bottom plate 146 is located below the agitation tank-side discharge port 171A, the flocs 106 contained in the water to be treated 104 can be guided to the bottom recess 147, which is lower than the bottom surface 141, and the sand pump 231 disposed in the bottom recess 147 can reliably suck up the water to be treated 104 containing the flocs 106.

[0100] Furthermore, in this embodiment, in the water treatment method using the water treatment device 101, the pressure-transfer selection means 238 has a flexible downstream pipe 236, and when the water to be treated 104 accumulates in the separation tank 108 to which the discharge port 237 of this downstream pipe 236 is connected, the discharge port 237 is moved to connect the discharge port 237 to another separation tank 108.Therefore, it is only necessary to stop the pressure-transfer of the water to be treated 104 and stop the pressure-transfer of the water to be treated 104 from the water receiving tank 107 only while the discharge port 237 of the downstream pipe 236 is being connected to the other separation tank 108, and the water to be treated 104 from the water receiving tank 107 can be discharged almost continuously, thereby shortening the overall treatment time.

[0101] As an effect of the embodiment, the angle of the inclined bottom plate portion 146 with respect to the horizontal is 15 degrees or more and 30 degrees or less, and is at least half the length of the inside of the water receiving tank 107 in the left-right direction (the distance between the inner surfaces of the side portions 144L and 144R), so that the water to be treated 104 containing flocs 106 that has fallen from the discharge outlet 171 can be guided to one of the side portions 144L.

[0102] Furthermore, hanging devices 152 are provided on the top of the water receiving tank 103, the mixing tank unit 37, and the water receiving tank 107, which facilitates the work of hanging them down, and also facilitates the work of transporting, assembling, and disassembling.

[0103] In addition, the opening and closing means 172 for the lid bodies 173, 173A is equipped with a hanging structure 178 for hanging the lid bodies 173, 173A, and the lid bodies 173, 173A move back and forth to open and close the discharge outlets 171, 171A.Therefore, compared to hinged lid bodies, the lid bodies 173, 173A can be opened and closed more widely, and the groundwater 102 and the treated water 104 can be smoothly dropped and supplied below.

[0104] Furthermore, as shown in Figure 16, the lower edges 171F of the discharge outlets 171, 171A of the receiving tank 103 and the stirring tank 105 are at the same height as the upper surfaces of the bottom portions 121, 131, so that the groundwater 102 and the treated water 104 can be discharged from the discharge outlets 171, 171A without accumulating and remaining inside.

[0105] A support rail 201, which is a support member that constitutes part of the suspension structure 178, protrudes from the center of the upper part of the discharge port 171, and this support rail 201 is in the shape of a plate, with an upper edge 202 that is formed so that it is slightly lower towards the tip. An upwardly protruding stopper 203 is provided at the tip of this upper edge 202, and a suspension member 205 that is hung on the support rail 201 is provided at the center of the upper outer surface of the lid body 173. Therefore, when the pressure inside the pressurizing cylinder 211 is reduced by operating the knob 214, the pressure of the fluid inside the fluid pressure cylinder 175, which has a higher pressure, decreases, and the lid body 173 retracts.

[0106] 13, the weight of the lid 173 is applied to the support rails 201 via the wheels 207, holding the lid 173 vertically, and the lid 173 is pushed by the fluid pressure cylinder 75, reliably closing the discharge port 171 with the lid 173. When the telescopic drive shaft 176 retracts from the closed state, the lid 173 retracts away from the discharge port 171, and the wheels 207 roll on the upper edge 202, which slopes downward toward the tip, and the lid 173 is suspended by the wheels 207. As a result, the lid 173 becomes tilted so that the upper edge of the lid 173 tilts forward, as shown in FIG. 7, and some of the groundwater 102 discharged from the discharge port 171 hits the inner surface of the lid 173 and falls into the mixing tank 105 below. Furthermore, the wheels 207 are locked to the stoppers 203, which act as stoppers, so that the wheels 207 do not come off the support rails 201.

[0107] A stirring blade 221 serving as a stirring means is provided within the stirring tank 105, and this stirring blade 221 has a horizontal rotating shaft 222 that is long in the front-to-back direction, and a pair of approximately rectangular, flat stirring plates 223, 223 are attached to this rotating shaft 222.By installing the stirring blade 221 that is long in the front-to-back direction horizontally within the stirring tank 105, which is longer in the front-to-back direction than the left-to-right direction, the height dimension of the stirring tank 105 can be reduced compared to when the stirring blades are installed vertically with the same volume, resulting in excellent processing capacity and transportability.

[0108] Furthermore, the diameter of the through-hole 224 is 30 mm, preferably 20 mm to 40 mm. If the through-hole 224 is too small, the resistance during rotation increases, while if the through-hole 224 is too large, the stirring effect decreases. However, by setting the diameter in this range, the rotation resistance can be reduced, and a stirring blade 221 with high stirring effect can be obtained.

[0109] Furthermore, the flocs 106 containing water sucked from the separation tank 108 by the sand pump 231 are packed into flexible container bags and allowed to naturally dehydrate on-site, and the dehydrated cake obtained after dehydration can be used as cultivation soil for plants, etc. Furthermore, the top water 109 from the separation tank 108 can be stored in the clean water tank 241 and used for daily life such as washing clothes and bathing. Furthermore, the present water treatment device 101 can be made smaller and lighter than conventional devices, and can improve water treatment capacity by 10 to 20 times. [Example]

[0110] FIG. 18 shows a fourth embodiment of the present invention, in which the same parts as those in the above-described embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

[0111] This example is a modified example of the pumping selection means 238, in which a branch pipe 251 is provided in the upstream pipe 235, an on-off valve 234A is also provided at the discharge port (downstream end) of this branch pipe 251, and two (a plurality) on-off valves 234, 234A are provided downstream of the upstream pipe 235. The downstream pipes 236, 236A are connected to the discharge ports of these on-off valves 234, 234A.

[0112] Therefore, the discharge ports 237, 237A of the downstream pipelines 236, 236A are connected to different separation tanks 108, 108, and the other on-off valve 234A is closed while one on-off valve 234 is open, and the sand pump 231 is driven to send the water to be treated 104 from the water receiving tank 107 to the separation tank 108.When the water to be treated 104 in the separation tank 108 becomes full, the other on-off valve 234A is opened without stopping the sand pump 231, and one on-off valve 234 is closed, and the water to be treated 104 is sent to the empty separation tank 108.

[0113] In this way, while the water to be treated 104 is being sent to the empty separation tank 108, the downstream pipe 236 connected to one of the on-off valves 234 can be connected to the empty separation tank 108, and the on-off valves 234, 234A can be switched in the same way.Even while the discharge port 237 of one of the downstream pipes 236 is being moved, the water to be treated 104 can be sent to the separation tank 108 from the discharge port 237 of the other downstream pipe 236A.This means that the water to be treated 104 can be sent continuously, and the treatment of the previous tanks 103, 105 will not be delayed due to the receiving tank 107 being full.

[0114] By using multiple separation tanks 108 in this way, even if one separation tank 108 becomes full, the water to be treated 104 in the receiving tank 107 can be continuously discharged with little waiting time, and water treatment can be carried out continuously and efficiently on site using the receiving tank 103, mixing tank 105, and receiving tank 107.

[0115] In this way, this embodiment also provides the same functions and effects as the above-described embodiments.

[0116] Furthermore, since this embodiment is provided with three or more separation tanks 108 and two or more flexible downstream pipes 236, 236A, the water to be treated 104 in the water receiving tank 107 can be continuously discharged.

[0117] The present invention is not limited to the above-described embodiments and can be modified in various ways. For example, while the pumping means in the embodiments is a submersible pump installed in a collection well, it can also be a pump installed above ground. Furthermore, in the second embodiment, an open-loop heat pump is shown, which pumps groundwater from a pumping well and returns it to a reinjection well. However, a closed-loop system, which returns the pumped water to the collection well, can also be used. Furthermore, while the embodiments describe a control system for one collection well, the control system can also control systems for multiple collection wells, or the collection wells can be operated manually. Furthermore, in claim 3, the collection pipes can be arranged in two or more stages spaced apart in the depth direction. Hereinafter, regarding the water treatment device, various means can be used for assembling and disassembling the water treatment device, other than those described in the embodiments. Bolts and nuts are preferred. Furthermore, the water to be treated can be treated by mixing bleaching powder, chlorine, slaked lime, dechlorination, etc. Furthermore, the opening and closing of the lid and the addition of the coagulant and disinfectant can be fully automated. Furthermore, although an on-off valve is provided in the pressure-feed selection means, the water to be treated sent from the water receiving tank may be switched from one of the downstream pipes 236, 236A to the other using a switching valve. Also, a part of each pipe in the embodiment may be an open flow path. Various disinfectants, such as sodium hypochlorite for water supply, may be used. Furthermore, water from river 9 may be used as raw water. [Explanation of symbols]

[0118] 1 Liquefaction prevention structure 2 Ground 3 Water collection well 4 Water collection pipe 5 Proximal opening 6. Submersible pump (pumping means) 22 Reservoir

Claims

1. A ground liquefaction prevention structure in which a collection well is placed in the ground that holds groundwater, and water that flows into the collection well is pumped up by a pumping means to lower the groundwater level in the ground, thereby preventing liquefaction of the ground, A plurality of the collecting wells are arranged at predetermined intervals; A plurality of water collection pipes arranged in the ground are connected to each of the water collection wells, A ground liquefaction prevention structure characterized in that groundwater that has flowed into the collection well from the collection pipe is pumped up by the pumping means.

2. 2. The ground liquefaction prevention structure according to claim 1, wherein the plurality of water collection pipes are arranged radially.

3. 2. A ground liquefaction prevention structure as described in claim 1, characterized in that the plurality of water collection pipes are arranged in multiple stages at intervals in the depth direction of the water collection well, and an opening / closing means is provided for opening and closing the base end openings of the water collection pipes.

4. 2. A method for utilizing a liquefaction prevention structure for ground according to claim 1, comprising storing the pumped groundwater in a reservoir for use.

5. 2. A method for utilizing a liquefaction prevention structure for ground according to claim 1, comprising utilizing the pumped groundwater for air conditioning or heating.

6. A method of using a liquefaction prevention structure as described in claim 5, characterized in that the groundwater pumped from the collection well is used for air conditioning or heating, and the groundwater after use is returned to another collection well.

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