JP2573398B2 - Method for measuring the level of underwater concrete - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial application field >> The present invention relates to the position of the top of a concrete poured (the boundary between underwater concrete and muddy water thereon) when concrete is poured into water by the tremy method. The present invention relates to a method for measuring the level of underwater concrete for measuring water.

<< Prior Art >> In the tremy method, it is necessary to grasp the top level of underwater concrete during casting as accurately as possible in order to appropriately control the pulling position of the tremy tube. For this reason, various measuring devices and measuring methods have been developed. As a technique for measuring the top level of concrete by submerging a plurality of pressure sensors in muddy water and underwater concrete, see JP-A-62-59721.
A publication is known.

In the above-mentioned prior art, four pressure sensors are attached to a long rod-shaped casing at predetermined intervals in the longitudinal direction, and this casing is suspended from a cable to sink substantially vertically in muddy water and underwater concrete, and the casing is raised and lowered. In addition to being able to be arranged at an arbitrary position, the position can be measured from the cable feeding length.

Then, the position of the casing is adjusted while comparing the outputs of the four pressure sensors, the upper two pressure sensors are located in the muddy water, and the lower two pressure sensors are located in the concrete. At this time, the concrete top level is known from the position of the casing.

<< Problems to be Solved by the Invention >> In the above-described conventional technology, the top level cannot be measured in a state where the casing is appropriately immersed in concrete. The sensors must be created in muddy water, with the bottom two sensors in concrete, and the casing must be raised as the concrete top rises to always maintain that condition.

In addition, if the interval between the sensors is increased, the above-described casing positioning operation is easy to perform, but the measurement accuracy deteriorates.
If an attempt is made to increase the accuracy by reducing the sensor interval, the measurement operation becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to accurately measure the top level of concrete by simply submerging a measuring instrument (corresponding to the casing) at an appropriate position in muddy water and concrete. The point is to be able to measure.

<< Means for Solving the Problems >> Therefore, in the present invention, as shown in FIG. 1, a pipe 6 with a closed bottom is disposed almost vertically in concrete 5 before solidification poured into water. Two differential pressure sensors 1 attached to the pipe 6 at predetermined intervals in the longitudinal direction with the upper end side of the pipe 6 opened into the muddy water 7 on the concrete 5 so that the inside of the pipe 6 is filled with the muddy water. And 2 to measure the differential pressure between the concrete pressure outside the pipe and the muddy water pressure inside the pipe 6, respectively, and denote the distance from the position of the differential pressure sensor 1 located below to the top of the concrete to y, Measured values of sensors 1 and 2 are ΔQ ₁ and ΔQ ₂ , differential pressure sensor
When the distance between 1 and 2 is z, The top level of the concrete is calculated and displayed by the equation.

<< Operation >> As shown in FIG. 1, the distance from the surface of the muddy water 7 to the concrete top is x, the distance from the position of the pressure sensor 1 to the concrete top is y, and the distance between the pressure sensors 1 and 2 is z. The specific gravity of the muddy water 7 is a, the specific gravity of the concrete 5 is b, the concrete pressure outside the pipe and the muddy water pressure inside the pipe at the position of the differential pressure sensor 1 are P ₁ and P ₃ , respectively. Assuming that ΔQ ₁ , the concrete pressure outside the pipe at the position of the differential pressure sensor 2 and the muddy water pressure inside the pipe are P ₂ and P ₄ , respectively, and the measured value of the differential pressure sensor 2 is ΔQ ₂ , the following equations hold.

ΔQ ₁ = P ₁ −P ₃ ΔQ ₂ = P ₂ −P ₄ P ₁ = ax + by P ₂ = ax + b (yz) P ₃ = a (x + y) P ₄ = a (x + yz) Solving the simultaneous equations gives the following equation.

Here, since the sensor installation interval z is known, both sensors
The concrete top level y can be obtained by a simple calculation of the pressure measurement values ΔQ ₁ and ΔQ ₂ of ₁ , ₂ .

<< Embodiment >> FIG. 2 shows a situation in which the method for measuring the level of underwater concrete of the present invention is applied to the tremy method for a continuous underground wall.

The tremy tube 8 is installed almost vertically in the muddy water 7 of the trench where the continuous underground wall is to be constructed, and is held at an appropriate height. Concrete is poured into the muddy water 7. Numeral 5 is the cast underwater concrete.

The above-mentioned pipe 6 used in the measuring method of the present invention is attached to the side of the tremy tube 8 in parallel with the tube 8 via a bracket 9, and is disposed substantially vertically in the muddy water 7 and the concrete 5 together with the tremy tube 8. You.

A fine wire mesh 10 is attached to the opening at the upper end of the pipe 6 to prevent concrete from entering the pipe 6 and to fill the inside of the pipe 6 only with muddy water.

The differential pressure sensors 1 and 2 are attached to the peripheral surface of the lower end of the pipe 6 at a predetermined interval in the longitudinal direction. The outputs of these sensors 1 and 2 are introduced to a display unit 12 on the ground through a sensor cable 11. The above-mentioned concrete top level y (FIG. 1) is obtained by the arithmetic circuit of the display device 12, and a known constant value is added to the y to calculate the distance from the lower end of the tremy tube 8 to the concrete top. ,
For example, it is displayed on a bar graph type display.

In the embodiment shown in FIG. 2, a plurality of proximity switches 13 are attached to the side surface of the lower end of the pipe 6 at predetermined intervals in the longitudinal direction. The proximity switch 13 does not turn on in the muddy water 7 but turns on when entering the underwater concrete 5. The output signals of these proximity switches 13 are also input to the display device 12 so as to determine whether or not both the pressure sensors 1 and 2 are in the concrete 5 from the output of the proximity switch 13. Sensor
The top level in a state where 1 and 2 are not in the concrete 5 is detected from the output of the proximity switch 13 and displayed.

<< Effect of the Invention >> As described in detail above, according to the method of the present invention, if the two differential pressure sensor parts attached to the pipe are submerged to an appropriate position in the underwater concrete, the position of the differential pressure sensor can be reduced. It is possible to accurately measure the top level of concrete based on the standard, and even if the top level rises with the placement of concrete, there is in principle no need to raise the pipes accordingly. Measuring instrument (casing)
There is no need to perform the troublesome measurement operation of adjusting the position up and down to find the top level.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the measuring method of the present invention, and FIG. 2 is a schematic configuration diagram of an embodiment in which the method of the present invention is applied to the tremy method. 1,2 ... Differential pressure sensor 5 ... Underwater concrete, 6 ... Pipe 7 ... Muddy water, 8 ... Tremy tube 9 ... Bracket, 10 ... Wire mesh 11 ... Sensor cable, 12 ... Display device 13 ... …Proximity switch

Claims (1)

(57) [Claims] 1. A closed pipe having a closed bottom is disposed substantially vertically in concrete before solidification poured into water, and an upper end side of the pipe is opened in the muddy water on the concrete, and the inside of the pipe is muddy. And the differential pressure between the concrete pressure outside the pipe and the muddy water pressure inside the pipe is measured by two differential pressure sensors attached to the pipe at predetermined intervals in the longitudinal direction. Y is the distance from the position of the differential pressure sensor located at the top to the concrete top, and Δ is the measured value of each differential pressure sensor.
When Q ₁ , ΔQ ₂ and the distance between the differential pressure sensors are z, A method of measuring the level of underwater concrete, wherein the top level of the concrete is calculated and displayed by an equation.