JP6727947B2 - Groundwater level lowering method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a groundwater level lowering method, and is a technology that enables appropriate and efficient management of groundwater level by realizing visualization (so-called visualization) of groundwater level distribution and automatic control of a pumping pump. Is.

Liquefaction occurs in the sandy ground with a high groundwater level, such as in a landfill, due to the shaking of the earthquake, which pushes up manholes and sewer pipes, causing them to project from the ground surface and incline buildings. ing. In order to prevent such a liquefaction phenomenon, improvement work must be performed on the ground where liquefaction is a concern.

There are various known liquefaction countermeasure methods that have been conventionally performed, and one of them is the groundwater level lowering method.As the groundwater level lowering method, deep well method, well point method, etc. It has been 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, and in order to supply fresh air or fresh water from the ground surface to the ground when lowering the groundwater level in the ground to be improved. The process of extending the perforated pipe to the ground, and establishing two or more wells in the ground at a predetermined interval, and pumping groundwater by the Superwell Point method while decompressing the surrounding area of the ground. By doing so, the process of bringing the ground to a substantially vacuum state, the process of repeatedly supplying fresh air or fresh water through the perforated pipe of the grout material supply facility extended from the ground surface into the ground, and the improvement target The process consists of returning groundwater in the ground to the natural groundwater level.

JP2012-180738A

By the way, in the groundwater level lowering method, it is necessary to lower the water level over the entire range of countermeasures to below the target lowering water level and maintain that water level for the required period. However, various problems remain in the conventional direction of lowering groundwater level.

For example, the groundwater level measured using an observation well is point information, and there is a problem that the groundwater level distribution cannot be grasped in a plane. Therefore, even if the groundwater level is lowered, the effect may not be surely exhibited, and there is a risk that the above-ground structure may be inclined due to the uneven settlement.

In addition, since the pumping pump is manually controlled to be turned on and off, there is a problem in that control and maintenance must be performed depending on the intuition of the operator. Therefore, there is a problem that not only there is a human risk such as a control error by the operator, but also a continuous burden is large because the maintenance is performed semipermanently.

The present invention has been proposed in view of the above circumstances, and it is possible to appropriately and efficiently manage the groundwater level by performing optimal control of the pumping pump by grasping the groundwater level distribution two-dimensionally. The purpose is to provide a simple groundwater level lowering method.

The groundwater level lowering construction method according to the present invention has the following features in order to achieve the above-mentioned object. That is, the groundwater level lowering method according to the present invention is a groundwater level lowering method for appropriately and efficiently managing the groundwater level in the ground to be improved by pumping water in a plurality of pumping wells. In the process of determining the pumping pattern by the combination of ON/OFF of the pumping pump in step 1, and for each pumping well, the parameter set of the pumping volume is obtained by the convergence calculation (simplex method), and the parameter set of the pumping volume is used to calculate the current The process of calculating the groundwater level distribution and the process of calculating the predicted groundwater level distribution when each determined pumping pattern is applied using the pumping sensitivity value of each pumping well obtained from the pumping test in each pumping well, and the current situation Using the value obtained by subtracting the predicted groundwater level distribution calculated from the above groundwater level distribution as the evaluation point, applying the process of calculating the total value of the evaluation points and the pumping pattern that maximizes the total value of the calculated evaluation points, And a step of controlling the pumping amount of each pumping well.

Further, it is preferable to include a step of visually expressing the current groundwater level distribution in each calculated pumping well. Further, in the step of controlling the pumping amount of each pumping well, it is preferable to control the pumping amount within the range of the upper limit water level and the lower limit water level set for each pumping well.

According to the groundwater level lowering method according to the present invention, it is possible to control the optimum pumping pump by determining the pumping amount of each pumping well by the convergence calculation using the simplex method and controlling the pumping amount of each pumping well. It will be possible to manage the groundwater level appropriately and efficiently by implementing.

In addition, by visually expressing the groundwater level distribution in the improvement target ground using the well formula of the group well based on the determined pumping volume, it is not point information for each observation well, but the entire improvement target ground. The groundwater level distribution can be grasped in a plane.

In addition, by controlling the amount of pumped water within the range of the upper limit water level and the lower limit water level set for each pumping well, the extreme difference in ground water level will be eliminated and the ground water level will be appropriately managed for the entire ground to be improved. be able to.

The flowchart of automatic pumping control in the groundwater level lowering construction method which concerns on embodiment of this invention. Image diagram of superposition of water level distribution. Explanatory drawing which shows the concept of the simplex method. A contour map showing an example of groundwater level distribution. Explanatory drawing which shows the image of automatic pumping control in each pumping well.

Hereinafter, a groundwater level lowering method according to an embodiment of the present invention will be described with reference to the drawings. 1 to 5 are for explaining a groundwater level lowering method according to an embodiment of the present invention, FIG. 1 is a flowchart of automatic pumping control in the groundwater level lowering method, FIG. 2 is an image diagram of superposition of water level distributions, and FIG. Is an explanatory diagram showing the concept of the simplex method, FIG. 4 is a contour diagram showing an example of groundwater level distribution, and FIG. 5 is an explanatory diagram showing an image of automatic pumping control in each pumping well.

<Outline of groundwater level lowering method>
The groundwater level lowering method according to the embodiment of the present invention is a technology that enables appropriate and efficient management of the groundwater level by visualizing (visualizing) the groundwater level distribution and automatically controlling the pumping pump. .. INDUSTRIAL APPLICABILITY The present invention calculates the current groundwater level distribution in each pumping well by a convergence calculation (simplex method), and predicts the groundwater when applying the pumping pattern (combination of ON/OFF of multiple pumping wells), which is the next step The evaluation point is calculated based on the difference between the water level and the target groundwater level, and the pumping pattern that maximizes the total value of the evaluation points among all the pumping patterns is applied to control the pumping volume of each pumping well. There is.

<Visualization of groundwater level distribution>
As shown in Fig. 2, the groundwater level distribution at any time at any point is in a transitional state until it shifts to a steady water level, and is expressed by superimposing the water level distribution (well formula) centered on each pumping well. it can. Since the well formula for group wells at arbitrary points is expressed by the following equation (1), the surface groundwater level distribution can be uniquely determined by determining the pumping volume Q _i (i=1 to n) of each pumping well. Can be expressed.

In the formula (1),
h _j : water level (m) at arbitrary point j
H: Groundwater level before pumping starts (m)
Q _i : Pumping volume of pumping well i (m ³ /s)
k: Permeability coefficient (m/s)
R: radius of influence (m)
r _i : Distance from pumping well i (m)
Represents.

<Convergence calculation>
In order to calculate the parameter set Q _i (i=1 to n: n=number of pumping wells) of the above equation (1) that can best approximate the current water level distribution, the convergence calculation by the simplex method was applied. That is, Q _i that minimizes the error between the observed water level and the calculated water level in each observation well is calculated based on the following procedure (see Fig. 3). Note that convergence calculations other than the simplex method may be performed as long as the current water level distribution can be approximated.

(A) Set n+1 parameter sets of the pumping amount (Q _{1 to} Q _n ) of each n pumping wells (setting of initial value).
(B) Calculate the groundwater level at each observation well point using equation (1) for the above n+1 parameter sets.
(C) The sum ΣΔh _j of the difference between the observed water level of each observation well and the calculated water level is calculated and plotted on the n-dimensional space. Here, a geometrical figure having these n+1 points as vertices is called a simplex.
(D) Of the vertices of the simplex, the maximum point (the point at which the sum of errors is maximum), the second maximum point, and the minimum point are extracted.
(E) Corrective actions such as mirroring/expansion/contraction/reduction are performed to update the simplex.
(F) Convergence determination is performed on ΣΔh _j for the updated simplex, and the above operation (e) is repeated until convergence is achieved.
(G) Evaluate the converged simplex vertex parameter set (Q _{1 to} Q _n ) as the optimum solution.

<Application example>
When the above method was applied to actual construction, for example, a contour map of the groundwater level distribution as shown in Fig. 4 could be obtained. As described above, according to the groundwater level lowering construction method according to the embodiment of the present invention, the groundwater level distribution can be visualized as a contour diagram, so that the manager or the worker accurately grasps the groundwater level distribution at the site. be able to.

<Automatic control of pumping pump>
After calculating the calculated water level in the improvement target range, optimal pumping pump control is performed in the improvement target range based on the procedure shown in FIG. Fig. 5 shows an image of automatic pumping control.

(A) A pumping pattern k (k=1 to 2 ⁿ : n=the number of pumping wells) is set by a combination of pump ON/OFF of each pumping well (S1).
(B) The current water level distribution is calculated by the convergence calculation using the simplex method (S2).
(C) When each pumping pattern is applied using the sensitivity obtained from the pumping test of a single well (the change in the water level at each node when the water level of the pumping well is lowered or raised by 1.0 m in the pumping test) The predicted water level distribution of is calculated (S3).
(D) The sum ΣΔh _{k of} evaluation points is calculated for each pumping pattern (S4).
(E) The pumping pattern that maximizes the total ΣΔh _{k of} evaluation points is applied to the control of the next step (S5).
Then, the procedure (S3(c) to S5(e)) described above is repeated in the set time cycle to automatically control each pump.

In addition, when lowering the groundwater level by the pumping pump, by setting the upper and lower limit water levels and controlling the pumping in each pumping well, it is possible to suppress the occurrence of an extreme groundwater level gradient that causes differential settlement.

S1-S5 Automatic pumping control process (step)

Claims (4)

A groundwater level lowering method for appropriately and efficiently managing the groundwater level in the ground to be improved by pumping water at multiple pumping wells.
Determining a pumping pattern by a combination of on/off of pumps in each pumping well;
For each of the pumping wells, a step of calculating a parameter set of the pumping amount by a convergence calculation, and using the parameter set of the pumping amount, calculating the current groundwater level distribution,
Using the pumping sensitivity value of each pumping well obtained from the pumping test in each pumping well, a step of calculating a predicted groundwater level distribution when applying each pumping pattern determined above,
A step of calculating a total value of the evaluation points, with a value obtained by subtracting the calculated predicted groundwater level distribution from the calculated current groundwater level distribution as an evaluation point.
Applying a pumping pattern in which the total value of the calculated evaluation points is maximum, and controlling the pumping amount of each pumping well,
A method of lowering groundwater level, which includes: The groundwater level lowering method according to claim 1, wherein the convergence calculation uses a simplex method. The groundwater level lowering method according to claim 1 or 2, further comprising a step of visually expressing a current groundwater level distribution in each of the calculated pumping wells. In the process of controlling the pumping amount of each pumping well, the pumping amount is controlled within a range of an upper limit water level and a lower limit water level set for each pumping well. Groundwater level lowering construction method described in paragraph.

Images