JPH06257137A - Stabilizing liquid water-level control method using atmospheric pressure sensor for underground continuous wall construction - Google Patents

Abstract

PURPOSE:To control the water-level of the stabilizing liquid appropriately by providing an atmospheric pressure sensor on the ground and on the water surface of an excavation channel, and computing the water-level on the basis of a difference of the atmospheric pressure, and computing a deviation between the computed water-level and the previously input water-level, and controlling a variable delivery pump so as to eliminate the deviation. CONSTITUTION:An atmospheric sensor 4B is provided on the water surface W of the stabilizing liquid for preventing collapse of an excavation channel 1, and an atmospheric pressure sensor 4A is provided on the ground at a fixed reference point Lo, and the water-level W is computed on the basis of a deviation between the atmospheric pressure of both the sensors. A deviation between the previously input water-level and the water-level obtained by the computing is computed, and in the case where a deviation exists, a variable delivery pump 7 is controlled to supply the stabilizing liquid so as to eliminate the deviation. The water-level of the stabilizing liquid is thereby maintained appropriately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to water level measurement and management of stable liquid in underground wall construction.

[0002]

2. Description of the Related Art The water level of a stable liquid during excavation in underground continuous wall construction must be accurately measured in order to prevent collapse of the excavation trench by the stable liquid.
There is one.

(1) As shown in FIG. 3, an ultrasonic distance meter 9 measures the distance to the water surface.

(2) As shown in FIG. 4, a lightwave rangefinder 1
The distance to the reflector 11 installed on the water surface is measured by 0.

(3) As shown in FIG. 5, the float 12 floating on the water surface measures the water level on the water surface.

[0006]

The above-mentioned conventional method has the following problems.

(1) Method using an ultrasonic range finder.

An erroneous measurement occurs due to suspended matter on the water surface, and the mounting place is affected by vibration.

(2) A method using an optical distance meter.

It is very difficult to follow the water surface with the planar position of the reflector plate fixed.

(3) Float method.

There is an error in reading the scale and it is affected by the specific gravity of the muddy water.

Therefore, an object of the present invention is to solve the above problems of the conventional method, to easily and accurately measure the water level of the stable liquid, and to perform accurate water level management. To provide a water level management method for

[0014]

To achieve the above object, according to the present invention, a floating body equipped with an atmospheric pressure sensor is installed on the water surface during excavation, and an atmospheric pressure sensor is installed at an immovable reference point on the ground. Then, the air pressure on the water surface and the air pressure at the immovable reference point on the ground are measured, and the water level of the water surface necessary to prevent the collapse of the excavation trench is input to the computer in advance, and the measured value at the immobile reference point is set. By calculating the atmospheric pressure of the water surface as the water level from the relative value of and the deviation between the water level input in advance and the water level obtained by the operation, if there is a deviation, send a control signal to the variable flow pump Then, the stabilizing solution is replenished and controlled so that the deviation becomes zero.

[0015]

The water level can be known from the relative value to the immovable reference point by measuring the atmospheric pressure by using the principle that the atmospheric pressure is reduced by 1 cm to decrease by one millionth of an atmospheric pressure.

Now, when the excavation progresses and the water level drops below the water level required to prevent the collapse of the excavation groove input in the computer in advance, the variable flow pump is activated by the control signal from the computer, or the discharge flow rate increases. When the water level on the water surface of the excavation groove rises and reaches the water surface level required to prevent collapse of the excavation groove, that is, when the deviation becomes zero, the variable flow pump stops or the discharge flow rate changes. Decrease. As a result, the water level on the surface of the trench will always be maintained at the water level necessary to prevent its collapse.

[0017]

EXAMPLE FIG. 1 shows a facility for carrying out the method of the present invention,
Reference numeral 1 is an excavation groove, 2 is a guide wall, and 3 is an excavator for excavating the groove. 4A is an atmospheric pressure sensor installed at the immovable reference point L0 on the ground, and 4B is an atmospheric pressure sensor installed on a floating body on the water surface W during excavation. Reference numeral 5 is a computer (CPU) for preliminarily inputting the water level of the water surface necessary for preventing collapse of the excavation trench, and 6 is a display device (CRT) for performing necessary display. Reference numeral 7 is a variable flow rate pump controlled by a control signal from the CPU, and 8 is a liquid supply pipe.

Next, the method for measuring and managing the water level of the stabilizing solution by the above facility will be described according to the flow chart shown in FIG.

The atmospheric pressure is raised by 1 cm to 100
It is possible to know the water level of the water surface W during excavation from the relative value with the immovable reference point L0 by measuring the atmospheric pressure by using the principle that the pressure decreases by one-tenth of an atmosphere.

The water level of the water surface required to prevent the collapse of the excavation trench is input to the CPU in advance (S-1).

The atmospheric pressure at the fixed reference point L0 and the atmospheric pressure at the water surface W during excavation are measured by the atmospheric pressure sensors 4A and 4B, and the measured values are input to the CPU (S-2).

The CPU calculates the atmospheric pressure of the water surface W to the water level based on the relative value with the measured value at the fixed reference point L0 (S-
3).

The deviation between the water level input in advance and the water level calculated is calculated (S-4).

No water level deviation (S-5).

If there is a deviation, a control signal is output from the CPU to the variable flow rate pump 7, and the stabilizing liquid is replenished and controlled so that the deviation becomes zero (S-6).

The necessary display is displayed on the CRT so that it can be visually confirmed.

The present invention is not limited to the water level control of underground continuous wall construction, but can be similarly applied to other vertical fluctuations and relative height measurement and control.

[0028]

Industrial Applicability The present invention uses the principle that the atmospheric pressure is lowered by 1 cm to 1 millionth of an atmospheric pressure.
Since the water level of the water surface during excavation is measured by the relative value with the immovable reference point by the atmospheric pressure measurement, erroneous measurement due to suspended matter on the water surface when using the conventional ultrasonic rangefinder, It is possible to eliminate the inconvenience such as the difficulty of measurement and the influence of the specific gravity of muddy water due to the float, to easily and accurately measure the water level of the stable liquid, and to perform accurate water level management.

[Brief description of drawings]

FIG. 1 is a front view showing a vertical section of an excavation groove in which a method for controlling the level of a stable liquid in a continuous underground wall construction using the atmospheric pressure sensor of the present invention is carried out.

FIG. 2 is a flowchart showing how the variable flow rate pump is controlled by the method shown in FIG.

FIG. 3 is a diagram showing a method using a conventional ultrasonic distance meter.

FIG. 4 is a diagram showing a method using a conventional optical distance meter.

FIG. 5 is a diagram showing a conventional float method.

[Explanation of symbols]

 1 ... Excavation groove 2 ... Guide wall 3 ... Excavator 4 ... Atmospheric pressure sensor 5 ... CPU 6 ... CRT 7 ... Variable flow rate pump 8 ... Liquid supply pipe

Claims (1)

[Claims] 1. A floating body equipped with an atmospheric pressure sensor is installed on the surface of water during excavation, and an atmospheric pressure sensor is installed at an immovable reference point on the ground, so that the atmospheric pressure on the water surface and the atmospheric pressure at the immobile reference point on the ground are set. The water level of the water surface necessary to prevent the collapse of the excavation groove is input to the computer in advance, and the atmospheric pressure of the water surface is calculated as the water level from the relative value with the measured value at the immovable reference point. The deviation between the input water level and the calculated water level is calculated, and if there is a deviation, a control signal is output to the variable flow rate pump to replenish the stabilizing liquid so that the deviation becomes zero. A method for controlling the level of stable liquid in underground continuous wall construction using a barometric pressure sensor.