JPH03281891A - Measurement of distance between inner walls of pit - Google Patents

Abstract

PURPOSE:To make automatic measurement of distance between inner walls of a pit available by a method wherein ultrasonic signals are emitted several times from an ultrasonic sensor provided in the pit and the received data are stored in a memory, and a distance corresponding to a peak point detected out of summed-up data is obtained. CONSTITUTION:An ultrasonic sensor 2 is hung down into stabilizing fluid in a pit 1 and ultrasonic signals are emitted (n) times to inner walls 2a, 2b of the pit from the sensor at a measuring position in a depth where the sensor is positioned, and reflected signals are received therewith. The received data are then amplified with an amplifier 7 in a reception recorder 6. Amplified analog data are then transmitted to the reception recorder 6 and are recorded on recording paper and are also transmitted to an analog-digital converter 8 and are written into a RAM. The received data in (n) by number are transferred to a CPU and are summed up with each of front positions of the data aligned on an axis of time. A peak point is detected out of the summed-up data with the data preceding a basic range eliminated, and distance data are displayed and recorded after correction is made.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for measuring the distance between inner walls of a vertical hole, such as a trench for forming a continuous underground wall, for measuring the distance between opposing inner walls of a vertical hole. .

(Conventional technology) For example, when constructing a continuous underground wall horizontally, after digging a trench, check whether the trench has been dug as designed or not, and check the distance between opposing inner walls (groove width). It is necessary to carry out preparation work such as sequentially measuring in the horizontal direction and measuring the amount of concrete to be poured into the groove from the obtained measurement data.

Conventionally, to measure the distance between opposing inner walls of a slot, an ultrasonic sensor is suspended in the slot, transmitting ultrasonic waves to each of the opposing inner walls of the slot, and receiving reflected waves from each inner wall. In Figure 1, A11A2 is the transmitted wave, Bl, B are the transmitted waves, and B1 and B are the transmitted waves. 1 reflected wave, C1 and C2 are 2nd reflected waves,
D, , C2 are the third reflected waves. Here, the distance ρ within the inner end of the first reflected wave B, , B, is the inner wall of the slot. In FIG. 5, the horizontal axis is scaled with distance, and the vertical axis is scaled with depth.

(Problems to be Solved by the Invention) However, in the conventional measurement method, the data recorded analogously on recording paper must be read by a working device and inputted into a computer, which requires manual labor.
In addition, there was a problem that it took time. Additionally, there is a problem in that reading errors are likely to occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for measuring the inner wall distance of a vertical hole, which allows automatic measurement.

(Means for Solving the Problems) To explain in detail the present invention for achieving the above object, the present invention suspends an ultrasonic sensor into a vertical hole to be measured, In a method for measuring the inner wall distance of a vertical hole in which the gap is measured by transmitting and receiving ultrasonic waves, ultrasonic waves are transmitted n times from the ultrasonic sensor to the inner wall at the depth position at the measurement address of the depth where the ultrasonic sensor is located. Measurement is performed while emitting a signal and successively receiving the reflected signals, digitally converting the obtained n received data at the same measurement address and writing it into the memory, and converting the n received data at the same measurement address read from the memory. The head positions of the received data are aligned and added together on the time axis, the data portions that deviate from the expected values are removed from the resulting added data, and then the peak point is calculated from the added data. It is characterized by searching for the peak point and finding the distance corresponding to the peak point.

(Operation) In this way, measurements are performed n times per measurement address at the same depth, and the obtained n pieces of received data are added together with their heads aligned on the time axis to obtain added data. Then, the transmitted signal in each received data and the reflected signal from the inner wall are each added n times at the same position on each time axis, and are emphasized to become a sharp signal. In the case of a trench for forming a continuous underground wall, the trench is filled with a stabilizing liquid to prevent the inner wall from collapsing, and since earth and sand are dispersed in this stabilizing liquid, reflections from these dispersed particles are The signal will also be present in the received data. Since the reflected signals from such dispersed particles are at various positions, they do not become large even if they are added together. If there is a lump of soil etc. in the liquid between the ultrasonic sensor and the inner wall5,
The reflected signals from there are added together and become larger, but since the position of this reflected signal is away from the expected position, for example, a basic range is provided for the reflected signal on this side of the inner wall, and those smaller than the basic range are Remove it as an unnecessary signal.

In this way, it is possible to search for a peak value in the added data from which obvious unnecessary signals have been removed, and to calculate the distance from the position of the peak value.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a measuring device for measuring the distance between opposing inner walls 1a and lb of a continuous underground wall forming groove (vertical hole) 1. Moreover, FIG. 2 is a flowchart 1 diagram showing the measurement procedure of the measuring device.

Hereinafter, the inner wall distance measuring method of this embodiment will be explained with reference to these figures.

The slot 1 is filled with a stabilizing liquid having a certain specific gravity and viscosity in order to prevent the inner walls 1a, lb from collapsing. In this way, the ultrasonic sensor 2 is suspended in the widthwise center of the slot with a pair of hanging wires 3a and 3b.
When the ultrasonic sensor 2 is suspended using the pair of suspension wires 3a and 3b, the ultrasonic sensor 2 does not become twisted and descends under its own weight along the widthwise center of the slot l. The cable 4 and the hanging wires 3a, 3b connected to the ultrasonic sensor 2 are the hanging wires 3a, 3a, which are fed out from the reel device f5.
3b can be determined by detecting the rotation angle of a guide roll (not shown) using a resolver or the like. Therefore,
The position of the ultrasonic sensor 2, that is, the measurement address of the slot 1 can be found.

Ultrasonic sensor 2 measures the depth at which it exists! An ultrasonic signal is emitted n times to the inner walls 1a and lb, and the reflected signals are successively received, and the received data is successively amplified by the amplifier 7 in the reception recorder 6. For ultrasonic signals, the level of reflected signals from nearby sources is high, and as the reflection position becomes farther away, the level of the reflected signals gradually decreases. For this reason, in the amplifier 7, the gain is once lowered every time the ultrasonic signal is emitted, and the gain is increased after one hour to amplify the received signal, thereby achieving a constant ratio of the level of the received signal.

The amplified analog reception data is led to the reception recorder 6 and recorded on recording paper as described above.

On the other hand, the amplified analog received data is
The data is input to the digital converter 8, and is sampled at high speed from step 5TI when the start trigger is input, and is converted to analog/digital conversion (hereinafter referred to as A/D conversion) to the random access memory of the hardware device (hereinafter referred to as A/D conversion).
(referred to as RAM) (step 5T2). This A
The /D conversion is performed at intervals that provide a distance resolution of, for example, 2 square meters. When the reception data for the same measurement address can be taken up to a position of, for example, 5 m in the direction of the wall surface of the slot 1, the measurement distance is deemed to have ended and the process proceeds to the next step (step 5T3).

At the end of step ST3, n pieces of received data for the same measurement address are written into the RAM.

Next, n pieces of received data at the same measurement address recorded in the RAM of the hardware device are transferred to the CPU in 8 (step 5T4). When the transfer of all n pieces of data is completed (step 5T5), proceed to step ST6, step ST
In step 6, the starting positions of n pieces of received data at the same measurement address are aligned and added together on the time axis.

That is. The first received data including the transmitted wave T1 and the reflected wave R from the wall surface of the slot 1 shown in FIG.
The transmitted wave T2 shown in FIG. 2B and the second received data including the reflected wave R2 from the wall surface of the slot 1 are added together with their leading positions aligned. With this operation, the transmitted waves T1 and T2
are added to obtain an additional transmitted wave with approximately twice the size as shown in FIG. 3(C), and reflected waves R1 and R2 are added to obtain As shown, an added reflected wave R having approximately twice the size is obtained. The noise components on each received data have irregular positions on the time axis, so the probability that the peak positions are added together is low.
The third received data is added in the same manner to the obtained addition data shown in FIG. 3(C). In this way, n for the same measurement address
received data are added, and the transmitted wave and the reflected wave have a magnitude that is enhanced with respect to noise. When n additions are completed (step 5T7), the process proceeds to the next step ST8.

In step ST8, a basic range is provided for reflected waves from a position before the distance from the ultrasonic sensor 2 to the wall surface 1a (lb) of the slot 1, and data before the basic range is removed. This operation removes the received data on the time axis that deviates from the expected position, so that reflected waves from a lump of soil or the like existing between the ultrasonic sensor 2 and the wall surface 1a (lb) are removed.

Next, proceed to step ST9. In step ST9,
A peak point is searched from the added data, and the address of the position of this peak point is distance data on the target wall surface 1 a (lb) (step 5710).

Next, proceed to step 5T11, this step 5T11
Then, a moving average of the obtained distance data is taken, and it is determined whether the distance data falls within a continuous groove wall gate consisting of the upper and lower limit values of the distance data. Distance data that does not fall within the continuous groove wall gate is discarded as an erroneous signal.

For the distance data that falls within the continuous groove wall gate, in the next step 5T12, corrections such as correction of the ultrasonic propagation velocity due to temperature are performed, or the corrected distance data is displayed on the display and printed on the printer. 10 and X-Y plotter 11
and record it on the floppy disk 12 (step 5T13).

Next, the process returns to step STI and the next measurement address is similarly measured.

FIG. 4 is a recording diagram of measurement data measured by the method of the present invention. Compared to the conventional measurement data shown in Figure 5,
The measurement data of the present invention has clean values with unnecessary signals removed. In addition, in this figure 4 as well, the distance is on the horizontal axis,
The depth is scaled on the vertical axis.

Based on such measurement data of the present invention, the volume of the groove for forming a continuous underground wall is calculated by the personal computer 9, and construction management such as determining the amount of concrete to be used is performed.

Note that in step ST8, data exceeding the upper and lower limits of the predicted value can be removed.

In the above embodiment, the present invention was applied to measuring the distance between the opposing inner walls of a continuous underground wall forming groove, but the present invention is not limited to this. This can be similarly applied to measuring the distance between (diameter).

(Effects of the Invention) As explained above, the method for measuring the inner wall interval of a vertical hole according to the present invention performs zero measurements per measurement address of the same depth, and aligns the heads of the obtained n pieces of received data. Since the data is summed by summing data when they are arranged on the time axis, the transmitted signal and the reflected signal from the inner wall in each received data are added n times at the same position on each time axis and are clearly emphasized. This has the advantage of providing a signal that

In addition, in the present invention, since those that deviate from the expected values are removed from the added data, unexpected signals such as reflected signals from particles that are present before reaching the inner wall are removed, which is compatible with the above-mentioned effect. This has the advantage that it is easy to extract the reflected signal from the inner wall, which is received mixed in with various unnecessary signals. Since the peak value is searched for in the added data processed in this way and the distance is calculated from the position of the peak value, it is possible to perform ultrasonic measurement in a stabilizing liquid mixed with earth and sand, etc.
The distance between opposing inner walls can be easily measured.

In addition, in the present invention, since the received data is converted into a digital signal and handled, the obtained measured value is also a digital value, so there is no need for the worker to read it, which saves labor and prevents reading errors. This has the advantage that it can be used immediately as an input signal for the next operation.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an example of an apparatus for implementing the method of the present invention, FIG. 2 is a flowchart showing the operating procedure of the apparatus of this embodiment, and FIGS. 3 (A), (B), and (C) are FIG. 4 is a waveform diagram showing an example of addition of received data in this embodiment. FIG. 4 is a diagram of measurement data by the apparatus of this embodiment, and FIG. 5 is a diagram of measurement data by the conventional apparatus. 1... Continuous underground wall formation groove (vertical hole), la, lb.
...Inner wall, 3a, 3b... Hanging wire 4... Cable, 5... Reel device, 6... Receiving recorder, 7...
...Amplifier, 8...Analog/digital converter, 9...Personal computer, 10...Printer, 11...X-Y plotter, 12...Floppy disk. Figure 1

Claims (1)

[Scope of Claims] A method for measuring an interval between inner walls of a vertical hole, in which an ultrasonic sensor is suspended in a vertical hole to be measured, and an interval between opposing inner walls of the vertical hole is measured by transmitting and receiving ultrasonic waves, wherein the ultrasonic sensor is present. Measurement is performed by emitting an ultrasonic signal from the ultrasonic sensor to the inner wall at the depth position n times at the measurement address of the depth and successively receiving the reflected signals,
The obtained n pieces of received data at the same measurement address are digitally converted and written into a memory, and the start positions of the n pieces of received data at the same measurement address read from the memory are aligned and arranged on the time axis. The method is characterized in that a data portion that deviates from the expected value is removed from the obtained added data, and then a peak point is searched for from the added data and a distance corresponding to the peak point is determined. A method for measuring the inner wall spacing of a vertical hole.