JPS61109817A - Well point drain work - Google Patents

Abstract

PURPOSE:To suck up ground water in deep layer by a method in which an air supply tube is provided inside, a well point is provided to the tip portion, and air bubbles are jetted from an air supply nozzle to obtain an air lifting effect, combined with a vacuum effect by a well point pump. CONSTITUTION:While jetting water jet stream from the tip 7 of a well point 5, a water-pumping tube 1 is penetrated into the ground 41 to form a vertical hole 39. Sand, etc., is packed into the hole 39 to form a water-permeable layer 43, and the upper end of the layer 43 is sealed up by a sealant 45, e.g., clay, etc. When the wall point 21 and an air supply pump 33 are operated, air bubbles from the nozzle 11 of an air supply tube 3 inserted into the tube 1 are jetted into ground water collected in the well point 5. With the rise of air bubbles, ground water is collected by air lifting effects and directed upwards in the tube 1 to a higher level than the water-pumping limit by the vacuum effect.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a well drainage construction method for pumping up deep underground water that exceeds the pumping limit by vacuum.

(Prior Art) A drainage method called the well point method is widely used to temporarily lower the groundwater level during excavation work such as digging for foundations, or for ground improvement work. This well point) ~ construction method involved burying a lift pipe with a well point at the tip, connecting a well point pot to this lift pipe, and pumping up groundwater by vacuum pumping5.
Here, pumping water using a vacuum has a limit determined by the relationship between atmospheric pressure and gravity on the water, and for efficient pumping, the maximum pumping depth is 6 to 7 m.

Therefore, conventionally, when pumping deep underground water that exceeds the vacuum pumping limit by the well point method, a multi-stage well point method as shown in FIG. 4 has been used. That is, the length of each pumping pipe 49 equipped with a well point 47 at the tip is within 6 to 7 m, and the first well-boiled pump 51 is used to raise the groundwater level by two points from the original water level indicated by the dashed line. Excavation is performed to lower the water level to the first stage water level shown by the chain line, and then the groundwater level is lowered by the second well point pump 53 from the first stage water level shown by the two-dot chain line to the second stage water level shown by the three-dot chain line. Then, the excavation is further progressed, and the process is repeated sequentially to excavate to the desired depth.

(Problem to be solved by the invention) However, in this conventional well point construction method, the ground water level is gradually lowered by arranging the well point pumps in a stepwise manner.
When lowering the groundwater level below the excavation level during construction work that involves excavation to a depth exceeding The present invention was developed with attention to these points, and even if adopted for construction work that involves excavation to a depth that far exceeds the pumping limit of vacuum, the present invention The purpose is to provide a well drainage construction method that does not require a large area around the site.

(Means for solving the problem) Therefore, in the well drainage construction method of the present invention, a pumping pipe with a well point at the tip is buried so that the well point is located at a predetermined position deeper than the pumping limit, and , insert an air supply pipe equipped with an air supply nozzle at the tip into the inside of the water pumping pipe so that the air supply nozzle is located in the screen portion of the well point, and use the water pumping pipe as a well point pump.

Furthermore, by connecting the air supply pipe to an air supply pump, it is possible to pump up deep underground water that exceeds the pumping limit by the interaction of the air lift effect caused by the air bubbles injected from the air supply nozzle and the vacuum pumping by the well point pump. This is what I did.

(Function) In the well drainage construction method of the present invention configured as described above, the air supplied from the air pump connected to the air pipe is sent into the groundwater collected from the screen part into the well point. Air is injected through a nozzle and rises in the underground water in the form of air bubbles.The air lift effect causes the groundwater to rise above the pumping limit, and then vacuum pumping is performed by a well point pump connected to the pumping pipe. This makes it possible to pump deep underground water that exceeds the pumping limit.

(Example) Next, an example of implementation of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram for explaining one embodiment of the well drainage construction method according to the present invention. In the figure, 1 is a water pump, 3 is an air pipe inserted into the water pipe 1,
5 is a well point attached to the tip of the lift pipe 1. The well point 5 includes a tip 7 for ejecting a jet water stream and a screen 9 that acts as a filter.

Reference numeral 11 denotes an air nozzle attached to the tip of the air pipe 3 and disposed near the screen portion 9 of the well point 5, the detailed structure of which is shown in FIGS. 2 and 3. Second
The figure is a longitudinal cross-sectional view of the same, and FIG. 3 is a plan view thereof. The air nozzle 11 has four small holes 15 opened diagonally upward and connected to a blind hole 13 to which the air pipe 3 is connected. and
It is fitted at an appropriate position between each of these 1 and the air supply pipe 3, and separates the passing air bubbles into smaller ones.

Reference numeral 21 denotes a well point pump. A water collecting pipe 23 is connected to the well point pump 21, and the bases of the plurality of water pumping pipes 1 are connected to the water collecting pipe 23 by swing joints 25. This well point pump 21 has an air/water separation tank 27. It is equipped with a water pump 29 and a vacuum pump 31. Reference numeral 33 denotes an air supply pump with a low pressure and a large air flow rate, and a plurality of air supply pipes 3 are connected to this air supply pump 33 via a branch pipe 35 by an air supply swing 37.

Reference numeral 39 denotes a vertical hole drilled deeper than the pumping limit in the ground 41 for excavation work such as foundation digging or ground improvement work, and the pumping pipe 1 is inserted through the vertical hole 39. 43 is a permeable layer of sand or the like filled in this vertical hole 39, and 45 is a sealing material such as clay that closes the upper end of the vertical hole 39.

In this embodiment, first, the water pump 1 is inserted into the ground 4 while jet water is injected from the tip 7 of the well point 5 at each predetermined position on the site where excavation work such as foundation root digging is being carried out.
Press fit into 1. As a result, a predetermined number of vertical holes 39, which are slightly deeper than the depth of excavation of the foundation, etc., are bored, and the water pump 1 is inserted into each of these vertical holes 39.

Here, the air supply pipe 3 is inserted through the water lift pipe 1 as described above. In this case, the tip of the well point 5 is set at a position approximately twice the diameter of the vertical hole above the bottom surface of the vertical hole. Next, each vertical hole 3
9 is filled with sand or the like to form a water-permeable single layer 43, and the upper end is sealed with a sealing material 45 such as clay. Thereafter, each of the water pumping pipes 1 is connected to the well point pump 21 via one water collection pipe 23, and each of the air supply pipes 3 is connected to an air supply pump via one branch pipe 35.

Here, the well point pump 21 and the air supply pump 3
3, air bubbles are injected from the pores 15 of the air nozzle 11 into the groundwater collected in the well point 5, and the air lift effect caused by the rise of these bubbles also causes the collected groundwater to flow through the pumping pipe. 1 and reaches a position higher than the pumping limit due to vacuum. The base of each pumping pipe 1 is connected to a water collection pipe 23 by a swing joint 25, and is connected to the well point pump 21 via this water collection pipe 23, so that groundwater that has reached a position higher than the pumping limit is The water is further raised by vacuum pumping, reaches the air/water separation tank 27 of the well point pump 21, and is separated into air and water, and the water is discharged separately by the water pump 29 and the air by the vacuum pump 31, respectively.

The inside of the pumping pipe 1 is in a reduced pressure state due to the action of the well point pump 29, and therefore, groundwater seeping into the permeable layer 43 from the peripheral wall of the vertical hole 39 is collected into the well point 5 through the screen portion 9.

In this case, the pressure air sent from the air pump 33 is 3
．． When using cooling pressurized air at 0 to 5.0°C.

The water collection efficiency can be more effectively increased by the temperature permeation effect that utilizes the affinity of soil due to the temperature difference with normal temperature groundwater (water temperature 15.0 to 15.5°C). Here, the bubbles injected from the air supply nozzle 15 are finely separated each time they pass through a bubble separator 119 placed at an appropriate position, thereby increasing the air lift effect and eliminating any negative effects on vacuum pumping.

The above has been described in detail according to the illustrated embodiment, but the present invention is not limited thereto.6 For example, depending on the nature of the ground, a vertical hole may be excavated in advance by poling or the like, and a pumping pipe may be inserted into the vertical hole. Alternatively, a casing is driven into the construction ground, a pumping pipe is inserted into the casing, the surrounding area is filled with a permeable layer, and then the casing is removed. It may be a construction method. Furthermore, depending on the soil quality, wood grain, etc., it is possible to omit the bubble separator, and there are also various variations in the number of pores, grooves, shape, etc. of the air nozzle.

(Effects of the Invention) The present invention is configured as described above, and pumps up deep underground water exceeding the pumping limit by the interaction of the air lift effect caused by air bubbles injected from the air supply nozzle and the vacuum pumping by the well point pump. This makes it possible to pump up deep underground water that far exceeds the pumping limit of vacuum pumps, and eliminates the need to arrange Well Point pumps in a stair-like manner.
It is easy to lower the groundwater level below the excavation surface in excavation work to a depth exceeding The effect is that the compaction progresses more quickly.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram for explaining an embodiment of the well drainage construction method according to the present invention, and Figs. 2 and 3 are longitudinal sectional views and plan views showing the detailed structure of the air supply nozzle used in this method. FIG. 4 is an explanatory diagram for explaining the conventional multi-stage well point construction method. ■... Lifting pipe, 3... Air pipe, 5... Well point. 9...Screen part, 11...Air supply nozzle. 21... Well point pump, 33... Air supply pump.

Claims (1)

[Claims] In a drainage construction method that pumps up deep underground water that exceeds the pumping limit by vacuum, a pumping pipe with a well point at the tip is buried so that the well point is located at a predetermined position deeper than the pumping limit, and this pumping Insert an air pipe with an air nozzle at the tip into the pipe so that the air nozzle is located in the screen part of the well point, and connect the pumping pipe to the well point pump, and connect the air pipe to the air pump. A well drainage construction method characterized in that deep groundwater exceeding the pumping limit is pumped up by the interaction of air lift effect by air bubbles injected from the air supply nozzle and vacuum pumping by the well point pump.