JP6347972B2 - Groundwater level lowering method and groundwater level lowering system - Google Patents

Description

  The present invention relates to a groundwater level lowering method and a groundwater level lowering system, and more specifically, a groundwater level lowering method and a groundwater level lowering that can be suitably used for lowering the groundwater level for liquefaction countermeasures and the like. It is about the system.

  In sandy ground with a high groundwater level, such as landfills, liquefaction occurs due to earthquake vibration, and manholes and sewer pipes are pushed up and protrude from the ground surface, and damage to the building can occur. ing. In order to prevent such a liquefaction phenomenon, improvement work must be performed on the ground where liquefaction is a concern.

  Various conventional liquefaction countermeasure methods are known, but one of them is the groundwater level lowering method, and as the groundwater level lowering method, deep well method, well point method, The kiln method is known.

  For example, as an example of the well point method, there is a ground improvement method described in Patent Document 1. This ground improvement method is a method for improving the ground by lowering the groundwater level. When the groundwater level in the ground to be improved is lowered, fresh air or fresh water is supplied from the ground surface into the ground. The process of extending the perforated pipe into the ground, and providing two or more wells in the ground at a predetermined interval, and pumping up the groundwater by the superwell point method, and simultaneously depressurizing the surrounding area in the ground The process of making the underground almost vacuum state, the process of repeatedly supplying fresh air or fresh water through the perforated piping of the grout material supply equipment provided extending from the ground surface to the ground, and the object of improvement It consists of the process of returning groundwater in the ground to the natural groundwater level.

JP 2012-180738 A

  In the construction method of lowering the groundwater level by pumping water from the improvement target ground, uneven settlement of the improvement target ground becomes a problem. That is, when the improvement target ground covers a wide area, the soil is not necessarily the same soil throughout the improvement target ground, and grounds having different hydraulic conductivity may be mixed. In such an improvement target ground, when pumping up uniformly, the displacement of the groundwater level occurs based on the difference in the hydraulic conductivity, which may cause uneven settlement.

  In addition, when multiple pumping wells are constructed in the ground to be improved, and groundwater is pumped from each pumping well, not only the difference in soil quality, Accordingly, the same groundwater level cannot be maintained over the entire area of the improvement target ground, resulting in uneven settlement.

  In this regard, the technique described in Patent Document 1 described above allows the ground to be improved to be unevenly subsidized, and as a countermeasure, the ground structure is lifted up using a permanent grout material. The settlement will be resolved.

  The present invention has been proposed in view of the above-described circumstances, and when lowering the groundwater level in ground improvement work or the like, by optimizing the pumping pattern and performing efficient pumping, uneven settlement is reduced. An object is to provide a groundwater level lowering method and a groundwater level lowering system that do not occur.

  The groundwater level lowering method and the groundwater level lowering system of the present invention have the following features in order to achieve the above-described object. That is, the groundwater level lowering method of the present invention relates to a method for uniformly reducing the groundwater level in the ground to be improved.

In this groundwater level lowering method, as a preliminary preparation, a plurality of pumping wells and a plurality of observation holes for measuring the groundwater level in the ground to be improved are constructed in the ground to be improved. Then, pumping water from each pumping well, measuring the groundwater level in each pumping well and each observation hole, and quantitatively calculating the relationship between the water level change in each pumping well and the water level change in each observation hole. The degree of influence that the water level change of each pumping well has on the water level change of each observation hole is calculated.

Thereafter, pumping up groundwater level in each pumping wells is uniformly predetermined depth, with measures the groundwater level in each pumping wells in and each observation hole, depending on the quantitative numerical phased influence The pumping well is used for pumping so that the groundwater level in the entire area of the improvement target ground is maintained at a predetermined depth.

  The groundwater level lowering system of the present invention is a system for uniformly lowering the groundwater level in the ground to be improved, and a plurality of pumping wells formed in the ground to be improved, and the groundwater level in the ground to be improved. And a plurality of observation holes for measurement.

And a pumping well water level measuring means for measuring the groundwater level of the pumping well provided in the pumping well, and an observation hole water level measuring means for measuring the groundwater level of the monitoring hole provided in the observation hole And each pumping well, pumping means for pumping groundwater from each pumping well, pumping by each pumping means, measuring the groundwater level in each pumping well by pumping well water level measuring means, By measuring the groundwater level in each observation hole by the observation hole water level measuring means and quantitatively quantifying the relationship between the water level change amount of each pumping well and the water level change amount of each observation hole, After quantifying the pumping influence degree to determine the degree of influence that the water level change of each well has on the water level change of each observation hole, and pumping by each pumping means, the groundwater level in each pumping well is uniformly set to a predetermined depth , Pumping well water With measuring the groundwater level in each pumping wells by measuring means, the groundwater level in each observation holes is measured by observing hole level measuring means, depending on the quantitative numerical phased impact, groundwater level in each pumping wells Is provided with pumping control means for controlling pumping by each pumping means so as to maintain a predetermined depth.

  In addition to the above-described configuration, the groundwater level lowering system of the present invention includes the groundwater level in each pumping well measured by the pumping well water level measuring means, and the groundwater level of each observation hole measured by the monitoring hole water level measuring means. Based on the above, it is preferable to provide a visualization display means for visualizing and displaying the groundwater level of the entire improvement target ground. Visible display of the groundwater level is implemented, for example, by creating and displaying a contour map.

In addition to the above-described configuration, the groundwater level lowering system of the present invention includes the impact level of each pumping well for each observation well, which is quantitatively quantified , and the current groundwater level of each pumping well and the groundwater level of the observation hole. based on the bets, it is preferable to provide a ground water level prediction means for predicting the groundwater level in the future.

According to the groundwater level lowering method and the groundwater level lowering system of the present invention, the groundwater level in each pumping well and each observation hole is measured, and the change in the water level in each pumping well and the change in the water level in each observation hole are calculated. By quantitatively quantifying the relationship, the degree of influence that the water level change of each pumping well has on the water level change of each observation hole is obtained. Then, depending on the quantitative numerical phased influence, as the groundwater level in the entire region of improved target ground is substantially the same, it is possible to perform pumping by pumping wells. Therefore, the pumping pattern is optimized, efficient pumping can be performed, and uneven settlement does not occur over the entire area of the improvement target ground.

Explanatory drawing which shows the whole structure of the groundwater level fall system which concerns on embodiment of this invention. Explanatory drawing which shows the principal part structure of the groundwater level fall system which concerns on embodiment of this invention. Explanatory drawing which shows the prior preparation in the groundwater level fall construction method which concerns on embodiment of this invention. Explanatory drawing which shows the pumping control (decrease in a groundwater level) in the groundwater level fall construction method which concerns on embodiment of this invention. Explanatory drawing which shows the pumping control (change of pumping pattern) in the groundwater level fall construction method which concerns on embodiment of this invention.

  Hereinafter, embodiments of a groundwater level lowering method and a groundwater level lowering system according to the present invention will be described with reference to the drawings. FIGS. 1 to 5 illustrate a groundwater level lowering method according to an embodiment of the present invention. FIG. 1 is an explanatory diagram showing the overall configuration of the groundwater level lowering system. FIG. FIG. 3 is an explanatory diagram showing preliminary preparation in the groundwater level lowering construction method, and FIGS. 4 and 5 are explanatory diagrams showing pumping control in the groundwater level lowering construction method.

<Outline of groundwater level lowering method>
In the groundwater level lowering method of the present invention, as shown in FIG. 1, a plurality of pumping wells 50 and a plurality of observation holes 60 for measuring the groundwater level in the ground to be improved are constructed in the ground to be improved, This is a method for reducing the groundwater level in the ground to be improved uniformly. The construction positions of the pumping well 50 and the observation hole 60 are not particularly limited. In order to prevent uneven settlement over the entire area of the improvement target ground, depending on the area of the improvement target ground, soil quality, surrounding environment, etc. Then, construct at appropriate positions (appropriate intervals).

<Groundwater level lowering system>
The groundwater level lowering system of the present invention is a system for carrying out the groundwater level lowering method. As shown in FIG. 2, the pumping well water level measuring means (pumped water level gauge 20) and the observation hole water level measuring means (observed water level). 300), pumping means (pumping pump 200), pumping effect quantification means 110, and pumping control means 120 are the main components. Moreover, it is possible to provide a visualization display means 130 and a groundwater level prediction means 140.

  The pumping well water level measuring means (pumped water level gauge 20) and the observation hole water level measuring means (observed water level gauge 300) are, for example, a commonly used water level gauge, and the pumping means (pumping pump 200) is, for example, generally used. It consists of a submersible pump. Further, the pumping influence degree quantifying means 110, the pumping control means 120, the visualization display means 130, and the groundwater level prediction means 140 are means constituted by a control device 100 including a microcomputer and its peripheral devices as shown in FIG. Although not shown in detail, the CPU or the like operates according to a program stored in a ROM, a RAM, or the like, and thereby functions as each means.

<Pumping well>
The pumping well 50 is a well for pumping water from the ground to be improved. As shown in FIG. 1, the pumping well 50 functions as a pumping pump 200 that functions as a pumping means and a pumping well water level measuring unit. A pumped water level meter 20 and an electrode 18 are installed. In the present embodiment, a pressure gauge 21 and a flow meter 22 are attached to a pumping pipe 19 that is connected to the pumping pump 200.

  Each pumping well 50 includes a manual control device 11, an automatic control microcomputer 12, an AD converter 13 and a dry contact 14, a relay 15 and an amplifier 16 as devices for controlling the drive of the pumping pump 200. A pump activation board 17 is provided. Each device is LAN-connected via a HUB 70 to a total control microcomputer 32 provided in a control room or the like. The total control microcomputer 32 is a device that constitutes an integrated computer 30 for integrating and controlling devices provided in each pumping well 50 and the observation hole 60. The integrated computer 30 includes a UPS / backup HDD 31 and a HUB 33 in addition to the total control microcomputer 32. Further, the integrated computer 30 is LAN-connected to the central computer 40 of the distributed control system via the HUB 33. In the present embodiment, these devices are collectively referred to as a control device 100.

<Pumping well water level measuring means (pumped water level meter)>
The pumping water level meter 20 that functions as a pumping well water level measuring means is a device for measuring the water level in the pumping well 50, a sensor that detects a liquid pressure (water head pressure) and outputs a detection signal, and floats on the water surface. A sensor that outputs a detection signal when a reed switch is activated by a magnet provided in the float, receives ultrasonic waves reflected from the groundwater surface, and measures the time difference between transmission and reception A known water level sensor, such as a sensor that converts the difference between the dielectric constant of groundwater and the dielectric constant of air and outputs a detection / measurement signal, can be used.

<Pumping means>
The pumping means comprises, for example, a pumping pump 200, and a pumping pipe 19 is connected in communication. The pumping pump 200 is installed in the groundwater in the pumping well 50, and the groundwater in the pumping well 50 is sent to the discharge tank 80 through the pumping pipe 19.

<Observation hole / Measurement means for observation hole level (observation water level meter)>
As shown in FIG. 1, the observation hole 60 is a vertical hole installed in the ground to be improved, and an observation water level meter 300 for measuring the groundwater level is installed in the observation hole 60. The observation water level meter 300 is a measuring device substantially the same as the pumped water level meter 20 described above. This observation water level meter 300 functions as observation hole water level measurement means.

<Control device>
As described above, the control device 100 includes the manual control device 11, the automatic control microcomputer 12, the AD converter 13 and the dry contact 14, the relay 15 and the amplifier 16, the pump starter 17, and the like provided in each pumping well 50. A total control microcomputer 32 connected to the electronic device by LAN and a centralized computer 40 of the distributed control system connected to the total control microcomputer 32 by LAN (see FIG. 1). As shown in FIG. 2, the control device 100 constitutes a pumping effect degree quantifying unit 110 and a pumping control unit 120.

<Measures for quantifying the impact of pumping>
The pumping influence degree quantifying means 110 pumps water by each pumping means (pumping pump 200), measures the groundwater level in each pumping well 50 by the pumping well water level measuring means (pumped water level gauge 20), and also observes the water level of the observation hole. By measuring the groundwater level in each observation hole 60 by the measuring means (observation water level meter 300), and quantitatively quantifying the relationship between the water level change amount of each pumping well 50 and the water level change amount of each observation hole 60. The program includes a program for determining the degree of influence that the water level change of each pumping well 50 has on the water level change of each observation hole 60 . The quantitative quantification by the pumping influence degree quantifying means 110 is a calibration that is performed in advance when pumping water in the improvement target ground, and by this quantitative quantification , the pumping pump 200 provided in each pumping well 50 is used. The tendency of groundwater level decline can be quantified and grasped.

<Pumping control means>
The pumping control means 120 performs pumping by each pumping means (pumping pump 200) and sets the groundwater level in each pumping well 50 uniformly to a predetermined depth, and then by the pumping well water level measuring means (pumped water level gauge 20). with measuring the groundwater level in each pumping wells 50, the groundwater level in each observation hole 60 is measured by observing hole level measuring means (observed water level indicator 300), depending on the quantitative numerical phased influence, each It consists of a program for controlling pumping by the pumping well 50 so that the groundwater level in the pumping well 50 maintains a predetermined depth. By controlling the pumping means (pumping pump 200) provided in each pumping well 50 using the pumping control means 120, the pumping is performed with the groundwater level substantially the same over the entire ground to be improved. Thus, uneven settlement can be prevented.

<Discharge tank>
The discharge tank 80 is a device for temporarily storing the groundwater pumped by the pumping means (pumping pump 200), adjusting so as to satisfy the discharge standard, and discharging it to a river or the like. The discharge tank 80 includes a control panel 81, a level meter 82, an AD converter 83, a relay 85 and an amplifier 86, a pump activation panel 87, an electrode 88, and discharge water as devices for controlling the storage and discharge of the discharged water. A pipe 89, a discharge water pump 90, a discharge water level meter 91, and an emergency shut-off valve 92 (combined electromagnetic opening / closing / manual use) are provided. The adjustment that satisfies the discharge standard is muddy water treatment, pH treatment, and the like.

<Procedure for lowering groundwater level>
Next, with reference to FIGS. 3-5, the procedure of the groundwater level fall construction method using the groundwater level fall system of this invention is demonstrated. The procedure for lowering the groundwater level can be roughly divided into a preliminary preparation process and an actual groundwater level lowering process.

<Preliminary preparation process>
As shown in FIG. 3, in the preliminary preparation process, pumping is performed using a pumping pump 200 in a plurality of pumping wells 50 constructed in the ground to be improved. At this time, in the plurality of pumping wells 50 drilled in the ground to be improved, the groundwater level is measured using the pumped water level gauge 20, and the groundwater level is measured using the observed water level gauge 300 in the plurality of observation holes 60. . Then, by quantitatively quantifying the relationship between the water level change amount of each pumping well 50 and the water level change amount of each observation hole 60, the effect of the water level change of each pumping well 50 on the water level change of each observation hole 60 is shown. Find the degree and quantify it quantitatively. The degree of influence quantitatively digitized is stored in a storage device (HDD or the like) of the control device 100 as a calibration value.

<Groundwater level lowering process with controlled pumping>
In the groundwater level lowering step, as shown in FIG. 4, the pumping pump 200 of each pumping means 50 is driven to pump water so that the groundwater level in each pumping well 50 is uniformly at a predetermined depth. While confirming the groundwater level of the observation hole 60, the drive of the pumping pump 200 of each pumping well 50 is controlled so that the groundwater level is uniformly maintained at a predetermined depth in all the observation holes 60. That is, when the groundwater level is higher than the target value, the pumping pump 200 is driven to pump the groundwater to the target value, and when the groundwater level is lower than the target value, the driving of the pumping pump 200 is stopped. The target groundwater level is appropriately set according to the condition of the ground to be improved, but is set to about minus 5 m from the ground surface, for example.

  Even after the groundwater level reaches the target water level, the measurement of the groundwater level in the observation hole 60 is continued. As shown in FIG. 5, when the groundwater level rises above the target water level, or the groundwater level of each observation hole 60 is When a difference of a predetermined value (for example, about ± 50 cm) occurs between them, the pumping pattern is changed and the pumping pump 200 of each pumping well 50 is driven to perform pumping so as to reach the target water level.

The pumping pattern is a driving pattern of the pumping pump 200 of each pumping well 50, and a plurality of patterns are stored in the storage unit of the control device 100 based on the quantitatively expressed degree of influence . And, it is a pumping pattern that can reduce the water level difference by comparing the measured groundwater level with the predicted value based on the quantitatively expressed degree of influence , and the water level difference with the current situation is minimized Select pumping pattern.

<Visualization of groundwater level drop>
The measured groundwater level can be visually displayed on the display screen of the display device 400 attached to the control device 100. In order to visualize the measured value of the groundwater level, the control device 100 includes a visualization display means 130 for visually displaying the measured value of the groundwater level. That is, the visualization display means 130 is based on the groundwater level in each pumping well 50 measured by the pumped water level meter 20 and the groundwater level of each observation hole 60 measured by the observed water level meter 300, and the groundwater level of the entire ground to be improved. Is visualized.

  The visualization display means 130 includes a program for two-dimensionally displaying a groundwater level distribution or displaying it as a three-dimensional graph using a plurality of display colors corresponding to the groundwater level. The image to be displayed is, for example, a contour diagram in which the groundwater level is color-coded with isolines.

Further, quantitatively quantify the degree of influence of the change in water level of each pumping wells 50 given to the water level change in each observation wells 60, to the current groundwater level groundwater level and observation hole 60 of each pumping wells 50 Based on this, it is possible to predict the future groundwater level. In order to predict the future groundwater level, the control device 100 includes a groundwater level prediction means 140 for predicting the groundwater level. The groundwater level prediction means 140, a degree of influence for each observation wells ized quantitatively numerically, based on the current groundwater level groundwater level and observation hole 60 of each pumping wells 50, to predict the groundwater level in the future For the program. The predicted value is visually displayed on the display screen of the display device 400 attached to the control device 100, for example, as a contour diagram in which the groundwater level is color-coded by isolines.

  Thus, by visualizing the measured value and the predicted value of the groundwater level, the manager and the operator can recognize the current groundwater level in the improvement target ground with real-time.

<Advantages of groundwater level lowering method and groundwater level lowering system of the present invention>
In the groundwater level lowering method and the groundwater level lowering system, it is preferable that an observation hole 60 exists between adjacent pumping wells 50. That is, when the observation hole 60 exists between adjacent pumping wells 50, the groundwater level at each point can be grasped based on the groundwater level of the observation hole 60.

However, in practice, there are various restrictions, and it is often difficult to arrange the pumping wells 50 and the observation holes 60 equally, and the number of the pumping wells 50 and the observation holes 60 is also limited. Under such circumstances, in the groundwater level lowering method and the groundwater level lowering system of the present invention, the groundwater level in each pumping well 50 and each observation hole 60 is measured, and the amount of water level change in each pumping well 50 and each By quantitatively quantifying the relationship with the water level change amount of the observation hole 60, the degree of influence that the water level change of each pumping well 50 has on the water level change of each observation hole 60 is obtained, and the quantitatively expressed degree of influence. Accordingly, since the pumping in the pumping well 50 is controlled, appropriate pumping management can be performed. Moreover, since the future groundwater level can be predicted, more appropriate pumping management can be performed.

DESCRIPTION OF SYMBOLS 11 Manual controller 12 Automatic control microcomputer 13 AD converter 14 Dry contact 15 Relay 16 Amplifier 17 Pump starting panel 18 Electrode 19 Pumping pipe 20 Pumping water level meter 21 Pressure gauge 22 Flow meter 30 Integrated computer 31 UPS, backup HDD
32 Total control microcomputer 33 HUB
40 General computer 50 Pumping well 60 Observation hole 70 HUB
80 Discharge tank 81 Control panel 82 Level meter 83 AD converter 85 Relay 86 Amplifier 87 Pump start panel 88 Electrode 89 Discharge water pipe 90 Discharge water pump 91 Discharge water level meter 92 Emergency shut-off valve 100 Control device 110 Pumping influence degree quantification means 120 Pumping control means 130 Visualization display means 140 Groundwater level prediction means 200 Pumping pump 300 Observation water level meter 400 Display device

Claims (4)

A groundwater level lowering system for uniformly lowering the groundwater level in the ground to be improved,
A plurality of pumping wells formed in the ground to be improved and a plurality of observation holes for measuring the groundwater level in the ground to be improved,
A pumping well water level measuring means provided in the pumping well for measuring the groundwater level of the pumping well;
An observation hole water level measuring means provided in the observation hole for measuring the groundwater level of the observation hole;
Pumping means provided in each pumping well, for pumping up groundwater from each pumping well;
Pumping by each pumping means, measuring the groundwater level in each pumping well by the pumping well water level measuring means, measuring the groundwater level in each observation hole by the observation hole water level measuring means , Pumping to obtain the degree of influence of the water level change of each pumping well on the water level change of each observation hole by quantitatively quantifying the relationship between the water level change amount of the pumping well and the water level change amount of each observation hole Impact quantification means,
After pumping up by each pumping means and uniformly setting the groundwater level in each pumping well to a predetermined depth, the groundwater level in each pumping well is measured by the pumping well water level measuring means, and the observation hole water level By measuring the groundwater level in each observation hole by the measuring means and according to the degree of influence quantitatively quantified , by each pumping means, the groundwater level in each pumping well maintains the predetermined depth. Pumping control means for controlling pumping,
A groundwater level lowering system characterized by comprising:   Visualization that visualizes and displays the groundwater level of the entire ground to be improved based on the groundwater level in each pumping well measured by the pumping well water level measuring means and the groundwater level of each observation hole measured by the observation hole water level measuring means The groundwater level lowering system according to claim 1, further comprising display means. And influence of the pumping wells for each observation wells turned into the quantitative numerical values based on the groundwater level of the current ground water level and the observation hole of the pumping wells, the groundwater level prediction means for predicting the groundwater level in the future The groundwater level lowering system according to claim 1, wherein the groundwater level lowering system is provided. A groundwater level lowering method for uniformly reducing the groundwater level in the ground to be improved,
In the ground to be improved, a plurality of pumping wells and a plurality of observation holes for measuring the groundwater level in the ground to be improved are constructed.
Pumping water from each pumping well, measuring the groundwater level in each pumping well and each observation hole, and quantitatively determining the relationship between the water level change in each pumping well and the water level change in each observation hole By obtaining a numerical value, the degree of influence that the water level change of each pumping well has on the water level change of each observation hole is obtained,
Pumping until the groundwater level in each pumping well is uniformly at a predetermined depth,
While measuring the groundwater level in each pumping well and in each observation hole, according to the quantitatively quantified impact, so that the groundwater level in the entire area of the ground to be improved maintains a predetermined depth, Performing pumping by the pumping well,
A groundwater level lowering method characterized by that.

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