JP3451382B2 - Underground water discharge method and drainage device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge method for forcibly discharging underground water such as ground water and ground water to the ground and a drainage device used for implementing the method.

[0002]

2. Description of the Related Art The Well Point method is well known as a method for forcibly discharging underground water. This construction method is a construction method in which a water absorption pipe having a large number of openings, that is, a so-called well point is penetrated into the ground, and then ground water is sucked up by the operation of a vacuum pump connected to the well point. In recent years, it has been practiced to use this well point in a ground improvement method. For example, in Japanese Utility Model Laid-Open No. 64-4909, a well point is inserted into a vibration compaction rod and the rod is driven into the well. A method of vacuum suctioning ground water (excess pore water) to the ground through well points is described.

[0003]

However, according to the method of discharging underground water by vacuum suction using the well point, the drainage depth is limited to the water head equivalent to atmospheric pressure (about 6 to 7 m), If you try to drain more than that depth, you will have to dig down the ground in multiple stages and place well points on each stage to gradually lower the groundwater level. In this case, the open excavation method must excavate a range that is several times the required excavation range,
The extension of construction period and the increase of construction cost will be unavoidable, while implementation by the ground improvement method will be virtually impossible.

As a countermeasure against the above problem, for example, in the ground improvement method, a mechanical pump may be installed in the vibration compaction rod instead of the well point (Japanese Patent Laid-Open No. 60-73912). In order to secure the installation space for the pump, a rod with a large diameter is required, which makes it difficult to penetrate into the ground.
Since the pump has to be installed in the rod accompanied by large vibration, its mounting structure becomes complicated, and there is another problem that it is not practical.

The present invention has been made in order to solve the above-mentioned conventional problems, and the problem is that it does not require a special construction method and is used from a position deeper than the water head equivalent to atmospheric pressure. An object of the present invention is to provide a highly practical underground water discharge method and drainage device that enable drainage.

[0006]

In order to solve the above-mentioned problems, the method of discharging underground water according to the present invention is such that the tip end is sealed.
After inhalation rod having a pressure chamber penetrate into the ground, the ground water is drawn into the pressure chamber by supplying a negative pressure from the ground to the pressure chamber, followed by supplying compressed air from the ground to the pressure chamber Then, the underground water in the pressure chamber is discharged to the ground.

Further, the drainage device according to the present invention comprises a suction rod having a closed pressure chamber at the tip thereof, and the suction rod has an air passage, a drainage passage and a water absorption passage from the outside to the pressure chamber. A passage is provided, a vacuum pump and a compressor installed independently of the rod are switchably connected to the air passage, and a drain pipe having an opening / closing valve is connected to the drain passage, and the drain passage is connected to the water suction passage. Is characterized in that a check valve for restricting a backflow from the pressure chamber is interposed. The drainage device may have a configuration in which two air passages are provided, in which case the vacuum pump is connected to one of the air passages and the compressor is connected to the other of the air passages.

[0008]

In the underground water discharge method and drainage device configured as described above, after the suction rod penetrates into the ground, the drainage passage is closed and a negative pressure is supplied from the vacuum pump to the pressure chamber of the suction rod. As a result, underground water can be sucked up into the pressure chamber regardless of the penetration depth of the suction rod, and the underground water in the pressure chamber opens the drainage passage to send compressed air from the compressor to the pressure chamber. The supply allows for drainage from a much deeper location than if well points were used.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a drainage device used in the method of discharging underground water according to the present invention. In the figure, reference numeral 1 is a tubular suction rod, and a filter chamber 4 having a closed pressure chamber 2 at its tip and a large number of pores 3 on its wall surface.
And are lined up. Inside the suction rod 1, an air supply pipe 5 providing an air passage and a drain pipe 6 providing a drain passage.
And a water absorption pipe 7 which provides a water absorption passage. The air supply pipe 5 and the drainage pipe 6 are largely extended in the axial direction of the suction rod 1, and both ends of the air pipe 5 and the drain pipe 6 define an end plate 8 and a pressure chamber 2 which are covered at the rear end (upper end) of the suction rod 1. It is supported by the partition wall 9a. The tip (lower end) of the air supply pipe 5 is inserted from the upper partition wall 9a into the pressure chamber 2 to a slight position, and the tip of the drain pipe 6 is deep inside the pressure chamber 2, that is, the pressure chamber 2 is partitioned. Lower partition wall 9
It is inserted up to the vicinity of b. On the other hand, the water absorption pipe 7 extends between the pressure chamber 2 and the filter chamber 3, and a part of the water absorption pipe 7 is supported by the lower partition wall 9b. In the pressure chamber 2, the upper end of the water absorption pipe 7 is bent in a U shape, and its opening is directed downward.

Reference numeral 10 is a vacuum pump, 11 is a compressor, both of which are installed on the ground and connected in parallel to a pipe 12 extending from the air supply pipe 5 via a three-way valve 13. The three-way valve 13 plays a role of switching the vacuum pump 10 and the compressor 11 with respect to the air supply pipe 5, and by operating the three-way valve 13, negative pressure and compressed air are selectively supplied to the pressure chamber 2. Will be done. Further, an extension pipe 15 provided with an on-off valve 14 is connected to the drain pipe 6, while a check valve 16 for restricting a reverse flow from the pressure chamber 2 to the filter chamber 4 side is interposed in the water suction pipe 7. There is. Further, the pressure chamber 2 is provided with a water level sensor (an electrode rod in this case) 17 for detecting the water level in the pressure chamber 2, and its signal is sent to a control device 19 on the ground via a signal line 18. It has become.
The three-way valve 13 and the on-off valve 14 can be automatically operated, and their operations are controlled by the control device 19.

In order to discharge underground water (groundwater in this case) using the drainage device constructed as described above, first, the suction rod 1 is penetrated into the ground 21 at a predetermined depth by using an appropriate driving machine. To do. Next, the on-off valve 14 in the extension pipe 15 of the drainage pipe 6 is closed, the three-way valve 13 is switched to the vacuum pump 10 side, and a negative pressure is supplied to the pressure chamber 2 through the pipe 12 and the air supply pipe 5. Then, the groundwater around the tip end of the suction rod 1 flows into the filter chamber 4 through the pores 3 and further into the pressure chamber 2 through the water suction pipe 7. As a result, the water level in the pressure chamber 2 gradually rises, and the rise in the water level is monitored by the water level sensor 17.

When it is confirmed by the water level sensor 17 that the water level in the pressure chamber 2 has reached a predetermined height, the control device 19 sends a switching signal to the three-way valve 13, and the three-way valve 13 causes the vacuum pump 10 to operate. Side to the compressor 11 side, whereby compressed air is supplied to the pressure chamber 2 of the suction rod 1. At the same time, the extension pipe 15 of the drain pipe 6
The opening / closing valve 14 therein is opened, and as a result, the groundwater in the pressure chamber 2 is discharged to the ground through the drainage pipe 6 and the extension pipe 15,
The water level gradually decreases. And finally, the lower end of the drainage pipe 6 is exposed on the water surface and the drainage is stopped,
At this stage, the three-way valve 13 is switched from the compressor 11 to the vacuum pump 10 again, and thereafter, the drainage is repeated batchwise by repeating the above operation.

As described above, according to the present drainage device, the negative pressure and the compressed air are alternately supplied to the pressure chamber 2 at the tip of the suction rod 1, and the position is far deeper than the head equivalent to the atmospheric pressure ( Groundwater can be discharged from 10 m or more). Further, since it is not necessary to install a pump or the like inside the suction rod 1, the structure of the suction rod 1 is simple and its size can be freely set. In the present embodiment, in particular, since one air supply pipe 5 is commonly used for negative pressure supply and compressed air supply,
The structure of the suction rod 1 becomes simpler. Further, since the filter chamber 4 is provided at the tip of the suction rod 1, the pressure chamber 2
Ingress of coarse particles into the interior is suppressed, and there is no risk of clogging the piping system. Needless to say, two air supply pipes 5 may be provided so as to correspond to the vacuum pump 10 and the compressor 11. Further, in the above-mentioned embodiment, the water level in the pressure chamber 2 is monitored by the water level sensor 17, but this water level is detected not by the water level sensor 17, but by, for example, a method by timer setting or a water level rise. It is also possible to adopt a method of detecting an increase in negative pressure.

FIG. 2 shows an example in which the drainage device is applied to open excavation. When using this drainage device, as shown in the upper side of FIG.
_{Even if the} suction rod 1 directly penetrates into the surrounding ground 21 of ₀ , the groundwater level L can be sufficiently lowered, so that the suction rod 1 penetrated close to the planned open excavation range S ₀ , for example.
A steel sheet pile 22 for retaining soil may be driven along the inside of the suction rod 1 or the inside thereof may be vertically dug down, or the inside of the suction rod 1 penetrating at a position slightly away from the planned open excavation range S ₀ may be dug down one step diagonally. It is possible, and the actual open excavation range S ₁ becomes narrow. On the other hand, in the case of using the conventional well point 23, as shown in the lower side of FIG. Even when it is used or when the steel sheet pile 22 is not used, it is necessary to dig down in two steps, and the open excavation range S ₂ is remarkably expanded as compared with the open excavation range S ₁ using the present invention described above. .

The participation of 3-6, the present invention akin drainage device
This is an example. The reference example is particularly characterized in the structure of the suction rod, and the suction rod 31 has a double pipe portion 34 of an outer pipe 32 and an inner pipe 33 concentrically arranged in the outer pipe 32. , The outer pipe 32 in the double pipe portion 34
A head portion 35 which is screwed into and integrated with each other, and a pressure chamber 36 is defined between the two. In the double pipe portion 34, the space between the outer pipe 32 and the inner pipe 33 is formed as an air passage 37, and the inside of the inner pipe 33 is formed as a drain passage 38. A vacuum pump 10 and a compressor 11 (FIG. 1) are switchably connected to the air passage 37 in the same manner as in the above embodiment, while the drain passage 38 also has the same manner as in the above embodiment. An extension pipe 15 (FIG. 1) having a switching valve 14 is connected with. In this reference example , since the air passage 37 has a relatively large volume, the pressure chamber 36 itself has a small volume.
A part of the pressure chamber 36 is replaced with the air passage 37.

Further, the head portion 35 is formed with a shaft hole 40 which is located on the shaft center thereof and opens to the pressure chamber 36, and a radius which communicates the inside of the shaft hole 40 with the outer periphery of the head portion 35. A plurality of lateral holes 41 in the direction are formed. The shaft hole 40 and the lateral hole 41 form a water absorption passage, and a portion of the shaft hole 40 near the pressure chamber 36 is provided with a conical valve seat 42 provided on the inner circumference of the shaft hole 40. A ball-shaped valve body 43 is arranged so that it can be seated and detached. The valve seat 42 and the valve body 43 constitute a check valve for restricting the backflow from the pressure chamber 36, and the valve body 43 is always seated on the valve seat 42 by its own weight. A stopper plate 39 is attached to the lower end of the inner pipe 33 to restrict the valve body 43 from coming off the shaft hole 40. Here, in the head portion 35, the portion in which the lateral hole 41 is formed is a small diameter portion 35a, and the thin diameter portion 35a does not protrude from the outer peripheral surface of the head portion 35 and is made of wire mesh or the like. The filter 44 is fitted through a plurality of support rods 45.

On the other hand, an injection nozzle 48 having a discharge passage 47 communicating with an axial through hole 46 formed in the head portion 35 is screwed and connected to the tip of the head portion 35. The discharge passage 47 of the injection nozzle 48 has a truncated cone-shaped injection port 49 at its lower end opening, and a valve body (check valve) 51 having a shaft 50 is arranged in the injection port 49. Has been done. The shaft 50 of the valve element 51 extends in the discharge passage 47 toward the head portion 35, and a spring 52 is wound around the extension portion. This spring 52
Is brought into contact with both ends of an upper spring bearing 53 which is prevented from coming off by an end flange 50a of the shaft 50 and a lower spring bearing 54 which is arranged on a step 47a in the discharge passage 47, so that the valve body 51 is normally moved upward. Urged to. As a result, the injection nozzle 48
The injection port 49 is normally closed by the valve body 51.

Hereinafter, a method of discharging underground water using the drainage device having the suction rod 31 will be described with reference to FIG. First, similarly to the above-described embodiment , the suction rod 31 is penetrated into the ground by using an appropriate driving machine. In this reference example , the opening / closing of the drainage passage 38 in the extension pipe 15 is performed at the time of this penetration. The valve 14 (Fig. 1) is closed and the three-way valve 13 is connected to the compressor 1
The compressed air is supplied to the air passage 37 by switching to the 1 (FIG. 1) side. The compressed air is closed from the on-off valve 14 and the valve body (check valve) 43 in the water suction passage (shaft hole) 40, so that the pressure chamber 36 passes through the through hole 4 of the head portion 35.
6 flows into the discharge passage 47 of the injection nozzle 48, opens the valve body 51 against the biasing force of the spring 52, and is jetted downward as an air jet from the jet port 49 (FIG. 7). As a result, the ground at the penetration tip of the suction rod 31 is excavated by the air jet, and the penetration of the suction rod 31 becomes extremely easy.

When the suction rod 31 penetrates into the ground at a predetermined depth, the on-off valve 14 is closed, the three-way valve 13 is switched from the compressor 11 side to the vacuum pump 10 side, and a negative pressure is applied to the pressure chamber 36 through the air passage 37. To supply. Then, the valve body 51 of the injection nozzle 48 closes the injection port 49, while the check valve 43 in the water absorption passage (shaft hole 40) is opened, and the groundwater around the head portion 35 passes through the filter 44 to form a large number of lateral holes 41. And then flows into the pressure chamber 36 through the shaft hole 40. In the present reference example , since the pressure chamber 36 has a small volume, groundwater is mainly sucked into the air passage 37 after filling the pressure chamber 36 (see FIG. 7).
). At this time, groundwater also enters the through hole 46 in the head portion 35 and the discharge passage 47 in the injection nozzle 48.

When the water level sensor (not shown) confirms that the water level in the air passage 37 has reached a predetermined height, the three-way valve 13 moves from the vacuum pump 10 side to the compressor 1 side.
It is switched to the 1 side, and compressed air is supplied to the pressure chamber 36 through the air passage 32. In accordance with this, the on-off valve 14 (FIG. 1) in the extension pipe 15 of the drainage passage 38 is opened, and the groundwater in the air passage 37 and the pressure chamber 36 is discharged to the ground via the drainage passage 38 (FIG. 7). . Since the fluid pressure in the pressure chamber 36 escapes to the drainage passage 38 when the opening / closing valve 14 is opened, the valve element 51 in the injection nozzle 48 does not open during the drainage.

In the above reference example , regarding the double pipe portion 34 of the suction rod 31, the space between the outer pipe 32 and the inner pipe 33 is an air passage 37, and the inside of the inner pipe 33 is a drain passage 38. However, the relationship between the two may be reversed, that is, the space between the outer pipe 32 and the inner pipe 33 may be configured as a drainage passage, and the inside of the inner pipe 33 may be configured as an air passage. Further, in the present reference example , the air jet is made to be jetted from the jet nozzle 48 during the penetration of the suction rod 31, but the present invention may be made to jet a water jet instead of jetting this air jet. It is a thing. In this case, for example, by connecting the vacuum pump 10, the compressor 11, and the water pump to the air passage 37 in a switchable manner, or by connecting the water pump to the drainage passage 38 in a switchable manner, it becomes possible to inject a water jet. .

8 and 9 show an example in which the drainage device according to the present invention is applied to the ground improvement method. In this case, the suction rod 1 in the above embodiment and reference example
And 31 are formed as small as possible, and they are provided at the tip of the vibration compaction rod 60.
The mounting member 62 is attached to each of the Nos. 1 and 2. In the ground improvement method, the vibration compaction rod 60
Is penetrated into the ground while vibrating by a vibrating hammer (not shown) or a vibrator built in the rod 60, excess pore water (ground water) is generated in the ground, but according to this embodiment, Regardless of the penetration depth of the vibration compaction rod 60, the ground water can be quickly discharged through the suction rod 1 or 31, and the ground can be efficiently consolidated. In addition, each suction rod 1 or 3
1 and a vacuum pump, compressor, etc. provided on the ground are connected by a connecting hose 63. Also, the vibration transmission blade 6
It is desirable to provide an opening 63 in 1 for allowing the circulation of ground water.

[0024]

As described above in detail, according to the method of draining underground water and the drainage device according to the present invention, the negative pressure and the compressed air are supplied to the closed pressure chamber at the tip of the suction rod. By alternately supplying and discharging underground water to the ground, it is possible to drain water from a position much deeper than when using the well point, and the excavation method that requires lowering the groundwater level,
This has the effect of being suitable for a ground improvement method or the like that requires drainage of ground water. Further, since the suction rod in the present drainage device does not include any mechanical power portion, the structure and shape are extremely simple, the handling is easy, and the utility value is remarkably improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing an embodiment of a drainage device according to the present invention.

FIG. 2 shows an example of application of the drainage system shown in FIG. 1 to an open excavation method, and is a schematic diagram showing a comparison with a conventional well point.

FIG. 3 is a sectional view showing a reference example of a drainage device similar to the present invention.

4 is a cross-sectional view taken along the line AA of FIG.

5 is a cross-sectional view taken along the line BB of FIG.

6 is a cross-sectional view taken along the line C-C of FIG.

FIG. 7 is a cross-sectional view showing a usage mode of the drainage device shown in FIG. 3 in order of stroke.

FIG. 8 is a schematic diagram showing an example of application of the drainage device according to the present invention to a ground improvement method.

9 is a sectional view taken along the line D-D of FIG.

[Explanation of symbols]

1 Suction Rod 2 Pressure Chamber 4 Filter Chamber 5 Air Supply Pipe 6 Drain Pipe 7 Water Suction Pipe 10 Vacuum Pump 11 Compressor 14 Open / Close Valve 16 Check Valve 60 Vibration Consolidation Rod

Claims (8)

(57) [Claims] 1. A suction rod having a closed pressure chamber at its tip portion is penetrated into the ground, and then a negative pressure is supplied to the pressure chamber from above to suck underground water into the pressure chamber. A method for discharging underground water, comprising supplying compressed air from the ground to the pressure chamber to discharge underground water in the pressure chamber to the ground. 2. The suction rod is externally attached to the vibration compaction rod.
Attached to the discharge method of underground water according to claim 1, characterized in that to penetrate both in the ground and the rod. 3. The pressure chamber is connected to the pressure chamber according to the water level in the pressure chamber.
Characterized by switching the negative pressure supply to compressed air supply
The method for discharging underground water according to claim 1 or 2 . 4. A suction rod having a closed pressure chamber is provided at a tip end thereof, and the suction rod is provided with an air passage, a drainage passage and a water suction passage communicating with the pressure chamber from the outside thereof, and the air passage is provided with: A vacuum pump and a compressor installed independently of the rod are switchably connected, a drain pipe having an opening / closing valve is connected to the drain passage, and a backflow from the pressure chamber is restricted to the water absorption passage. A drainage device characterized by having a check valve interposed. 5. The suction rod comprises a pipe member, and the air passage and the drainage passage are provided by respective independent pipe members inserted in the suction rod.
The drainage device described in. 6. A suction locker having a closed pressure chamber at its tip.
The suction rod is provided with a pressure chamber from the outside.
There are two air passages leading to the
Installed in one of the air passages independently of the suction rod
Connected vacuum pump and to the other side of the air passage
Connect a compressor installed independently of the suction rod
Then, connect a drain pipe equipped with an on-off valve to the drain passage,
A non-return valve in the water absorption passage for restricting backflow from the pressure chamber.
A drainage device characterized by having a valve interposed . 7. A filter is provided in front of the water absorption passage.
The water discharge device according to any one of claims 4 to 6, wherein: 8. A rising position of the water level is detected in the pressure chamber.
A water level sensor is provided, and the water level sensor is provided.
The drainage device according to any one of 1.