JPS61262673A - Method for searching underground embedded article - Google Patents

Abstract

PURPOSE:To attain to enhance searching accuracy, by falling a transmitter or a receiver forming a transmitting receiving system in a boring hole excavated from the surface of the ground and together using the same along with the transmitter or receiver on the surface of the ground. CONSTITUTION:The boring hole 7 of an embedded article 4 is excavated from the surface of the ground 1 and a transmitter 2 is lowered in said hole 7 and, when a pulse signal is emitted from said transmitter 2, the reflected pulse from the embedded article 4 is received by the receivers 51-5n provided on the surface of the ground. The results are analyzed by a computer 6 and the position of the embedded article 4 can be accurately confirmed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Objective of the Invention) The present invention relates to a method for exploring underground objects such as electric cables.

In order to improve the urban landscape, instead of the conventionally widely used overhead power distribution system, underground power distribution methods are increasingly being adopted. The use of recently developed large-scale civil engineering machinery is most effective. However, underground construction of roads in urban areas (2) is difficult because gas pipes, water pipes, etc. are often buried, and power cable construction is difficult. It is necessary to prevent accidental damage to these existing structures when excavating trenches for this purpose.

(Prior art and its problems) However, in the conventional technology (; the depth of burial of these existing buried objects,
Due to the insufficient accuracy of actual position measurements, it is difficult to introduce large civil engineering machinery, so construction work has to proceed with caution by manually digging trenches. If the depth and position of existing underground objects can be measured with high accuracy, there is no risk of accidentally damaging the existing objects even when using high-speed excavation equipment, reducing construction time and costs. becomes possible.

For example, as shown in Figure 1, a method for detecting the location of existing buried objects is to place two transmitters (2) on the ground surface (1),
Based on the high frequency pulse signal from the oscillator (3), the high frequency pulse is emitted underground as shown by the solid line in the figure. Then, the reflected waves from the buried object (4) are transmitted to the oscillator (3) and a plurality of receivers (1) placed on the ground surface (1) at regular intervals.
51) (52) (5,)...(5n)...
As shown by the dotted line in the figure, the received signal Pr2. Pr
3+...Prn are introduced into the computer processing circuit (6). The arithmetic circuit then uses the transmission time of the transmission signal and the arrival time of each received signal to send it to, for example, a receiver (5□
).

However, this method has the disadvantage that measurement sensitivity is poor depending on conditions near the ground surface, and sensitivity varies depending on the measurement point, making it difficult to quickly and accurately locate existing buried objects. The present invention has been made for the purpose of providing an exploration method that eliminates the above-mentioned drawbacks, and will now be described in detail with reference to the drawings.

(Means of the Present Invention) The present invention is based on the results that revealed that the decrease in measurement sensitivity as described above is greatly influenced by the reflection of the pulse near the ground surface where the transmitter/receiver is placed and the difference in the reflection conditions. It was conceived and done. For example, in general, the ground surface in urban areas is exposed as it is, or is covered with asphalt, or reinforced with concrete blocks, so the pulse emission surfaces of the transmitter are facing each other. The reflection conditions of the ground surface on which it is placed vary.

Therefore, the power of the pulse that reaches the buried cable from the ground surface (2) varies depending on the reflection conditions of the ground surface at the measurement point; However, since the pulses propagated through the soil are received through asphalt, etc., this also causes a reduction and fluctuation in the reception level.

A feature of the present invention is that the transmitting system or the receiving system forming the transmitting/receiving system can be lowered into, for example, a bore hole drilled at the measurement point by a drill, without using asphalt reinforcement or the like. Propagate the pulse directly into the soil or
Alternatively, the reliability of exploration can be increased by receiving signals propagated through the soil without going through asphalt reinforcement, minimizing the influence of ground surface conditions on the transmission/reception system. It is something.

FIGS. 2 and 3 are diagrams of one embodiment of the present invention (same symbols as in FIG. 1 indicate equivalent parts), of which the example in FIG. 4) Borehole (
7) and lower the second transmitter (2) inside.

As a result, as shown by the dotted line in the figure (= after emitting a pulse signal, the reflected pulse (shown by the dotted line in the figure) from the buried cable (4) is received by a receiver (5□) (5°) installed on the ground surface...
...(5n).

In addition, the example shown in Figure 3 shows the receiver (5) being lowered into the borehole (7) for exploration (in this case, the upper part is exposed as it is on the ground surface). If there is, it is not necessary to locate all receivers in the ground.

In addition, in Figures 2 and 3, the more the number of receiving points for each electrical pulse transmitting point, from several to several hundred, the more accurate the position of the buried object can be confirmed. Switch the electric pulse transmitting point and receiving point, transmitting point 2 is receiving point 5□ 52.53...5n transmitting point 5□ is receiving point 2. 5.53...5n transmitting point 52 So, the receiving point is 2.5, 53...5n, the transmitting point is 5n, and the receiving point is 2,5□, 52...5n-0. By analyzing the results with a computer and obtaining a cross-sectional image of the buried object, the location of the buried object can be confirmed even more accurately.

In this way, all you need to do is to create a small and shallow borehole that allows the transmitter to be lowered into the ground, and then add a simple and quick operation to lower the transmitter.
To avoid as much as possible the decrease in measurement sensitivity due to the influence of the ground surface,
Exploration accuracy can be improved. Note that the present invention can also be applied to the exploration of other underground objects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional method, and FIGS. 2 and 3 are diagrams of an embodiment of the present invention. (1)...ground surface, (2)...transmitter, (
3) ... oscillator, (4) ... existing buried object,
(5□) (52) (53)...Receiver, (6)...
...computer processing circuit, (7) ...borehole.

Claims (1)

[Claims] A transmitter placed on the ground emits electrical pulses into the soil,
In a method of detecting underground objects by receiving reflected electrical pulses from underground objects using multiple receivers installed on the ground surface, the transmitter or receiver forming the above-mentioned transmission/reception system is placed on the ground surface. An underground object characterized by improving accuracy by lowering it into a borehole drilled from the ground to form a transmission/reception system and using it in combination with a transmitter or receiver on the ground surface to increase the number of measurement points. exploration method.