RU2670175C1 - Method of georadar survey of underwater linear objects - Google Patents

Abstract

FIELD: geophysics.SUBSTANCE: invention relates to geophysics, namely to georadiolocation under environmental conditions of natural attenuation of electromagnetic signals, and can be used to detect linear objects, in particular pipelines, communication lines, etc. Method for georadar tracking of underwater linear objects using antenna device for a georadar containing body, unshielded antenna unit including receiving and transmitting units associated with the control and registration units and made in a hermetic version in the form of a semi-flexible hose towed by means of a vehicle, body of the device is made in plan in a Y-shape and includes parts of the lateral braces and a straight guide composed of a strong non-slip and non-metallic material, the maximum adjustable angle between the lateral braces being 135 degrees, for this purpose an arc-shaped crossbeam is installed at the outer side of the body, arc-shaped crossbeam simultaneously serves as a guide for the runner-slider of the movable beam moving between the braces by means of a drive with remote control, and a transmitting unit is attached to the movable beam from the underwater side, and to the direct guiding body – the receiving unit, control of which is carried out through the control and registration units, including the driving of the assembled antenna device towed by a water vehicle, through the inspection zone of the underwater linear object with tacks at tacking, the optimal angle α of the primary attack is predetermined for this purpose, depending on the position of the axis of the object under study, on which the position of the axis of the transmitting unit relative to the axis of the receiving block is set, then, at probing the underwater space at the time of detecting the linear object with the registration unit a hyperbola is fixed, and after a complete passage over the desired linear object, by turning the transmitter of the antenna unit set a parallel position to the direction of the desired linear object and again pass until it re-intersects with the object, while the number of repeated passages by maneuvering is determined by the task for inspection of the object, upon completion of which analyze the obtained data recorded during the sounding by the registration unit, and by intersection points establish linear mapping (section) of the position of the object.EFFECT: use of the invention allows to increase the efficiency of georadars in the survey of linear underwater objects, including deepwater surveys and surveys of linear engineering structure located in the bottom sediments.1 cl, 4 dwg

Description

The invention relates to geophysics, and in particular to georadar in the environment in which the natural attenuation of electromagnetic signals occurs, and can be used to detect linear objects, in particular pipelines, communication lines, in deep water bodies and / or under a layer of bottom sediments.

Various technical solutions are known in the field of subsurface radar, using, as a rule, georadars with antennas of various designs, aimed generally at sensing the underground space, in particular thawed and permafrost.

For example, a method of georadar location of permafrost (see RU No. 2490671, class G01V 3/12, G01S 13/88, publ. 08/20/2013), involving sounding with multiple measurements of signals in a radius of 3-5 m around the points of exploration or monitoring geological and geophysical network according to deterministic schemes with elements of randomness according to the location and orientation parameters of receiving and transmitting georadar antennas. The need for multiple measurements of signals with a change in the position and azimuth of GPR antennas cannot contribute to the effective use of the known technical solution in the search for underwater objects.

A known method of studying the topography of the river bottom and its deformation using a georadar and GPS receiver with reference to the terrain for subsequent storage and use (see KR No. 20040092508, G01V 3/00, filing date 04.11.2004), which consists in the following: GPR, consisting of a control unit for transmitting / receiving signals, is installed on water transport. Measurements are taken from the surface of the water. Data exchange between the GPR and the GPS receiver is carried out using an information processing unit, which includes devices for storing topographic information and location data, a memory card for storing an electronic map, software for creating a river bottom relief map and an output block for displaying a river relief map bottom. The method allows to study the relief of the river bottom, while not measuring the thickness of bottom sediments. It can be used to search for local objects, but is not suitable for the study of linear underwater objects.

It is known that for surveying linear submarine structures, commercially available OKO-type georadars with antenna units, for example, ABDL Triton type (see www.geotech.ru), built in unshielded construction, consisting of receiving and transmitting blocks with blocks, are used power connected to each other through an interface or optical cable. Antenna blocks are sealed in the form of a semi-flexible hose, can work under water and on rough terrain, and are equipped with emitters with a frequency range from 35 to 100 MHz. When sensing underwater objects, the antenna unit is usually towed by a water vehicle.

When using unshielded linear antenna blocks of the ABDL Triton type in the search for linear engineering objects underground or under water, for example, pipelines, cables, etc., if you pass over linear engineering objects, crossing them perpendicularly, then the georadar will not be able to detect them, because for GPR, a linear object is visible as a local object the size of the width of a linear object.

For this reason, the most effective way to find them is when the transmitter and receiver of the georadar are parallel to a linear object. However, this situation in practice is difficult to fulfill in the absence of initial information about the location of the linear object, in addition, the dimensions of the linear antenna unit are on average more than 5 m, depending on the center frequency of the linear antennas, which does not contribute to the quality of research.

A known method of research tacks, in which a linear antenna unit passes at a certain angle to the linear object of the search. But in this case, another problem arises, associated with establishing the optimal position angle of the transmitter of the antenna unit relative to the direction of the desired linear objects. The optimum angle will be achieved if the transmitter is parallel to the linear object, while the position of the receiver of the antenna unit should be aligned with the axis of the vehicle direction with the attached georadar antennas.

The problem to which the present invention is directed, is to increase the efficiency of georadar research of underwater linear objects.

The technical result obtained by using the invention is expressed in improving the efficiency of the use of georadars equipped with unshielded linear antenna units when examining linear underwater objects.

To solve this problem, a method of georadar research of underwater linear objects using an antenna device for georadar containing a housing, an unshielded antenna unit, including receiving and transmitting units associated with control and registration units, and made in a sealed version in the form of a semi-flexible hose, towed using , for example, a vehicle, while the housing of the device is made in plan in a Y-shape and includes parts of the side braces and a direct guide, left from strong (rigid) non-sinking and non-metallic material, moreover, the maximum adjustable angle between the side braces is 135 degrees, for which, an arc-shaped crossbar is installed on the outside of the casing, at the same time serving as guides for the runner sleeve of the movable beam moving between the braces, for example, by means of a drive with remote control, moreover, a transmitting unit is attached to the movable beam from the underwater side, and a receiving unit is attached to the direct guide of the housing, the control is which is carried out through control and recording units, for example, a laptop computer or other recording device, includes driving an assembled antenna device towed by a water vehicle through the inspection area of an underwater linear object with tacks during tacking, for which the optimal primary attack angle α is previously determined depending on the position of the axis of the object under study, which adjusts the position of the axis of the transmitting unit relative to the axis of the receiving unit, then when probing a single space at the moment of detecting a linear object by the registration unit, a hyperbole is fixed, and after a full passage over the desired linear object, the antenna unit transmitter is rotated at an angle of 2α, setting a parallel position to the direction of the desired linear object and again pass until it intersects with the object, with the number of repeated passages by maneuvering is determined by the task of examining the object (shooting detail), at the end of which the received data is analyzed, recorded during the probe tion registration unit, whereby at intersection points build linear mapping (cut) an object position.

A comparative analysis of the characteristics of the claimed solution with the signs of analogues indicates the conformity of the claimed solution to the criterion of "novelty."

The combination of features of the utility model provides a solution to the stated technical problem, namely, increasing the sounding efficiency by standard georadars equipped with unshielded linear antenna units when examining hidden objects, including in conditions with hindered or natural attenuation of electromagnetic signals, for example, in deep-sea or mineralized water bodies, or in cases where a linear engineering structure is located in bottom sediments.

The antenna device is illustrated by drawings, where in FIG. 1 schematically shows a housing with a movable beam, in FIG. 2 - placement of devices of the antenna unit to the housing, where “W” is the line of the water surface, in FIG. 3 is a diagram of an inspection of an underwater object with tacks when using an antenna device, FIG. 4 - samples of comparative images of georadars.

An antenna device for ground penetrating radar consists of a housing consisting of three parts: two lateral braces 1 and a direct guide 2, made of non-sinking and non-metallic material, for example, of plastic sealed pipes or wood (see Fig. 1). In this case, the housing parts are made, for example, collapsible and rigidly fixed to the detachable connection 3 and by means of an arched crossbar 4 made of non-metallic material, for example, from durable types of plastic.

The crossbar 4, fixing the side braces 1 on the detachable connection, also sets the required angle between the braces 1, which can be within 135 degrees, depending on the working conditions for the examination of objects.

The crossbar 4 also serves as a guide for the runner sleeve 5 of the movable beam 6, made of non-metallic material, for example, plastic or wood. The beam 6 can be made with a drive (including with remote control), while depending on the embodiment, a drive device that rotates the beam 6, for example, through a gear system, can be installed at the junction of 3 parts of the housing, this beam 6 rests on the other end of the beam 4. In another embodiment, the drive device is installed in place of the sleeve 5 and moves the beam 6 on the beam 4 by means of a drive slider, while the beam 6 is supported by the other end on the movable support of the connection 3 body parts.

Direct guide 2, in particular, is used to connect the antenna device of the georadar to a water vehicle, for which, from the front, it has a hook for towing.

The lateral braces 1 and the straight guide 2 can be additionally equipped with underwater stabilizers necessary to hold the antenna device on the surface of the water during sounding along the (parallel) direction of towing.

On the underwater side, the transmitting unit (transmitter) 7 of the antenna unit is mounted on the movable beam by known methods, and the receiving unit (receiver) 8 is mounted on the direct guide of the housing (see Fig. 2). In this case, the transmitter 7 and receiver 8 are connected to the control and registration units and are sealed in the form of a semi-flexible hose, for example, by analogy with the device of the Triton ABDL antenna unit (see www.geotech.ru).

The antenna unit is controlled through the control and registration units (laptop computer or other recording device) placed for work, for example, on board a watercraft.

The claimed antenna device for ground penetrating radar works as follows.

At the inspection site, the antenna device is assembled, starting from the connection of the body parts - side braces 1, direct guide 2, arcuate crossbeam 4 and movable beam 6 with drive and remote control. At the same time, depending on the working conditions for examining objects, the user sets the necessary angle between the braces, for example, in the range of 45-135 degrees. Further, from the underwater side of the movable beam 6 and the direct guide 2, the elements of the antenna unit are attached - the transmitter 7 and the receiver 8. Their connection with the control and registration units, which are located on the water vehicle directly at the user, is established. Thus prepared antenna device with ground penetrating radar is engaged with the water vehicle 9 (see Fig. 3).

The device can be used in different cases, for example, when determining the position (direction) of a linear object.

In a stationary body of water (without current), it is necessary to establish a position of the georadar in which the center between the receiver 8 and the transmitter 7 will be directly above the object under study 10. Turning the transmitter 7, observe the amplitude of the reflected signal on the registration device. In the absence of depolarization of electromagnetic signals in the aquatic environment, the position of the transmitter 7 with the observed maximum amplitude of the reflected signal will be the direction (axis) of the linear object. Moreover, if the amplitude of the signal reflected from the object does not change when the position of the transmitter 7 changes, this means that the object is not linear, but local.

To determine the depolarization angle of electromagnetic signals depending on the properties of the water, it is necessary to find either the existing linear structure in the studied reservoir, or independently bury the linear object with a length of at least double the length of the transmitting and receiving antennas. Next, set the position of the movable beam 6 with the transmitter 7 to a neutral level at which the beam 6 is at the same axial level with the direct guide 2, and determine the location of the sensing as the location of the center between the receiver 8 and the transmitter 7 directly above the test object 10. It is important, so that the combined axis of the transmitting and receiving antenna coincides with the axis of position of the linear object. Turning the transmitter 7 first to one side, and then to the other, they observe through the registration unit the amplitude of the reflected signal. When determining the maximum amplitude of the reflected signal, the angle formed between the axes passing through the straight guide 2 with the receiver 8 and the movable beam 6 with the transmitter 7. This angle will correspond to the angle of depolarization of the signals in the studied aqueous medium.

According to regulatory documents, when operating product pipelines, it is necessary to regularly conduct inspections of linear engineering structures at river crossings. When studying linear engineering structures in deep water bodies, as a rule, the axis of the location of the pipeline is initially known, for example, by pickets of its coastal outlets. Knowing the axis of the position of the pipeline, you can enter this data into the GPS navigator and adjust the angle between the positions of the movable beam 6 with the transmitter 7 and the straight guide 2 with the receiver 8 so that the transmitter 7 is always parallel to the pipeline axis when crossing the pipeline. For example, if the survey is carried out with tacks at an angle of 45 degrees, you need to have transmit-receive antennas at an angle of 45 degrees. In this case, it is necessary to change the angle in the opposite direction (mirror), depending on the side of the intersection of the axis of the pipeline.

With such a survey, the reflected signals from pipelines will always be with maximum amplitudes, which is very important when examining in deep water bodies (or in a highly mineralized body of water), where electromagnetic signals attenuate naturally. A study using the inventive device of georadar antennas will also be effective in cases where a linear engineering structure is located in the bottom sediments, which leads to attenuation of signals and requires the use of more energy to detect objects.

In the same cases, when the position of a linear heterogeneity is not known in advance and the problem is related to its search, then setting the axis position of the movable beam 6 with the transmitter 7 at an angle of 45 degrees relative to the axis of the straight guide 2 with the receiver 8, helps to expand the overview (search) of linear heterogeneity . In this position, even with a perpendicular intersection of a linear object, a reflected signal will be received.

Search operations using the claimed antenna device for ground penetrating radar are carried out in the following order.

For example, at the first stage of the survey of linear engineering structures at river crossings, an assembled antenna device with a georadar towed by a water vehicle 9 “attacks” towards the object under study 10 at the optimal alpha angle (see Fig. 3), the value of which is previously determined according to the position of the axis of the investigated object on landfalls. The position of the axis of the transmitter 7 relative to the axis of the direct guide 2 with the receiver 8 is adjusted to the same angle “alpha”. Thus, the user sets the best manifestation of the reflected signal corresponding to the parallel position of the transmitter 7 to the underwater linear object 10. The speed of the devices on the surface of the water when sensing is 0.3-2.5 m / s.

When approaching an object by a user who continuously probes the underwater space, a hyperbole is recorded at the moment of detection of a possible object by means of a registration unit (laptop computer or other recording device). In this case, the direction and speed of the towing vehicle 9 remain unchanged during the intersection of the investigated object 10.

After a full passage over the desired linear object 10, the towing vehicle 9 is turned by an angle "alpha" in the direction of the investigated object 10, while the transmitter 7 is simultaneously set to a neutral position.

In the next step, the towing means 9 and the transmitter 7, each separately, are simultaneously turned towards the object 10 by an angle of "alpha", setting the transmitter to the parallel position of the object 7 to the object 10, and swim until the linear object 10 intersects again. Thus, the cycle repeats the required number times in the form of tacks intersecting a linear object 10.

In FIG. 4 presents comparative images in the study of linear underwater objects in difficult conditions (deep water bodies, the presence of a large thickness of bottom sediments) obtained using the claimed antenna device.

The data show that when the pipeline crosses at a certain angle at which the axis of the transmitter 7 is parallel to the axis of the linear engineering structure, the pipeline in the form of a hyperbole is well detected (see Fig. 4B and Fig. 4C), in contrast to the other case when the transmitter 7 crosses the pipeline at an angle of 90 degrees, at which the object is no longer detected (see Fig. 4A). It should be noted that when using the claimed device, the number of hyperbolas reflected from various local objects, such as large boulders and local metal objects, is reduced.

As a result of such a survey, the reflected signals from the pipelines will be obtained with maximum amplitudes, which is important when examining in deep water bodies (or in a highly mineralized body of water), where the attenuation of electromagnetic signals occurs. It is also effective in cases where a linear engineering structure is located in bottom sediments, where attenuation also occurs, and more energy is needed to detect the object.

Claims (1)

 The method of georadar research of underwater linear objects using an antenna device for georadar, comprising a housing, an unshielded antenna unit, including receiving and transmitting units associated with control and registration units, and made in a sealed version in the form of a semi-flexible hose, while the device body is made in plan in the Y-shape and includes parts of the side braces and the direct guide, composed of rigid non-sinking and non-metallic material, with the maximum reg the measurable angle between the side braces is 135 degrees, for which an arcuate crossbeam is installed on the outside of the casing, at the same time serving as a guide for the runner sleeve of the movable beam moving between the braces, and a transmitting unit is attached to the movable beam from the underwater side, and to the direct guide of the body the receiving unit, which is controlled through the control and registration units, including the passage of the assembled antenna device, towed by a water vehicle, the survey area of the underwater linear object with tacks during tacking, for which the optimal primary attack angle α is preliminarily determined depending on the position of the axis of the object under investigation, which adjusts the position of the axis of the transmitting unit relative to the axis of the receiving unit, then when probing the underwater space at the moment of detecting the linear object by the registration unit a hyperbole is fixed, and after a full passage over the desired linear object, the antenna unit transmitter is rotated through an angle of 2α, setting the paral The final position to the direction of the desired linear object and again passes until the intersection with the object again, while the number of repeated passes by tacking is determined by the necessary shooting detail, upon completion of which the obtained data are analyzed at the intersection points recorded during the sounding by the registration unit, and a linear display of the object’s position is built .

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