IL44554A - Method for the detection of underground objects - Google Patents

Method for the detection of underground objects

Info

Publication number
IL44554A
IL44554A IL44554A IL4455474A IL44554A IL 44554 A IL44554 A IL 44554A IL 44554 A IL44554 A IL 44554A IL 4455474 A IL4455474 A IL 4455474A IL 44554 A IL44554 A IL 44554A
Authority
IL
Israel
Prior art keywords
ground
clay
product
colouring
water
Prior art date
Application number
IL44554A
Other versions
IL44554A0 (en
Original Assignee
Lead
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lead filed Critical Lead
Publication of IL44554A0 publication Critical patent/IL44554A0/en
Publication of IL44554A publication Critical patent/IL44554A/en

Links

Classifications

    • EFIXED CONSTRUCTIONS
    • E02HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02DFOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D1/00Investigation of foundation soil in situ
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01VGEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V9/00Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00
    • G01V9/007Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00 by detecting gases or particles representative of underground layers at or near the surface

Landscapes

  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Analytical Chemistry (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Soil Sciences (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
  • Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)

Description

Method for the detection of objects LEAD (lABORATOIRB B · XECTROUQUE WS D' AOTOMATIQTJE BAOTHINOIS) C. 42707 METHOD FOR THE DETECTION OF UNDERGROUND OBJECTS The invention concerns a method for the detection of buried objects, in which the profile of these objects is visually displayed, directly at the surface of the ground: it is thus possible to effect the overall de-tection (which is distinguished from an object-by-object detection) of the series of underground objects structures, without excavating into the ground and without punctually scanning the surface.
It is a known method to use punctual magnetic pro-bes for detecting, punctually, underground metallic objects, that method having been developped for finding explosive mines with a magnetic probe carried by a man or a self-propelled vehicle.
It is a known method to use radar sets for de-tecting, at slight depths, metallic or non-metallic objects, using the metallic reflection or local discontinuity in the dampness of the ground. By a suitable choice of the wavelength and of the echo display techniques, it is thus possible to obtain a general visual display, in cer-tain conditions, of underground objects.
It is a known method to use the measuring of the diffusion of carbon dioxyde as a localized measurement; the existence of a barrier in the ground prevents the moving of the gas, so that the rate of diffusion of the gas at the surface of the ground above or beside the buried object is different.
It is a known method to use a localized detection of hydrogen atoms contained in a great number of objects buried by men (plastic substances, explosives, etc.) by a rapid neutron moderation detector.
It is also a known method to use chromatography in a gaseous state as a method for localized detection of volatile compounds of the objects to be detected, as in the case of all explosives and a number of organic products.
Lastly, the overall thermoscopic or thermographic method, which uses the principle of the infra-red radiometer, detecting and displaying graphically slight differences in temperature due to the variation in the exchange of humidity with the surface above and beside buried objects is known.
The aim of the invention consists in producing a method for the detection of underground objects or structures by an overall method in which direct visual display gives an underground "image".
Moreover, the method according to the invention makes it possible to detect buried objects or structures made of any material, since it is based on the occultation 44554/2 Λ effect or "shadow* effect caused by that object or structure and not on the quality of that material.
More particularly, the method according to the invention enables the detecting of buried objects or structures at a distance, that is, without being in direct contact with the surface of the ground.
Lastly, the method according to the invention makes it possible to detect underground objects or structures situated only approximately or even whose exac presence is unknown, although it is being searched for.
There is provided in accordance with an embodiment of the invention a method for detection of underground objects or structures, characterised in that a thin layer of a mixture of products is spread on a ground surface, said thin 7 " layer having a sub-layer o a clay substance which is used for trapping the water vapou at the surface of the ground an for defining a threshold humidity concentration; said thin layer having another substance, which is a colouring product sensitive to water which diffuses and reacts with said layer thereby to cause a visual contrast in colour and brilliancy between the groun in which the object or the structure is constituted and the surrounding ground.
To provid a solution for these tasks, the invention provides for the simultaneous use of the following principles s difference in pressure gradient of water vapour at the surface of the ground, above or beside the buried object, slowing down of the transfer speed of waiter between the ground and the atmosphere by a controlle adsorption effect of that water by a spread product, local variation in the water contents adsorbed at the surface of the ground, above or beside the buried ob ect, colouring of that spread product by an incorporated colouring agent for which the adsorbed water acts as a solvent and therefore enables it to dissolve and colour the surface, that colouring then being a function of the quantity of water adsorbed, that Is, of the existence of a buried structure. $he method according to the invention may therefore be described as follows : The basic principle is that a buried object such as a mine, for example, constitutes a barrier for the rising or lowering movements of the water vapour in the ground: the result of this is that there is a discontinuity in dampness at the surface of the ground. During fine weather, the ground above a mine has a surface which is more dry than that of ground which is not mined and, conversely, subsequent to rain, the ground above the mine is more damp than the surrounding ground, since the flow of water is impeded by the mine, which forms a "shadow".
Then, according to the invention, a layer slowing down that exchange is formed by the spreading of a layer of clay, for example, which set3 up a "double barrier" effect or "adsorption" effect. That clay is intended, indeed, for trapping the maximum quantity of water vapour and defining a threshold of concentration of dampness based on which the colouring product can act, this having the effect of increasing the contrast in colour between the parts of the ground containing or not containing a buried object. That clay may be saturated with any salt, assisting in the forming of the layer of cations necessary for setting up that trapping effect, stopping the water coming from the ground by evaporation. The accumulation of the water in the vicinity of the clay surface is more or less great according to the original transfer speed, which, in its turn, depends on the partial water vapour saturation gradient caused by the exchanges mentioned.
Moreover, that layer of clay contains colouring products placed in suspension. The adding of salts makes a diffusion appear for a relatively slight dampness, in which case the apparent thickness of the adsorbed layer increases and the diffusing of the colouring substances may take place. The same effect takes place, without salts, for a greater relative humidity; that is why the double barrier effect described, increasing the water concentration artificially, is used.
That diffusion then colours the clay in a way which is very easily seen and, due to the variations in the concentrations of water, by the variable punctual gradient, the buried objects or structures appear in direct view.
Another advantage of the method according to the invention consists in the very slight quantities of indicator necessary and in that these products can be spread by air, like the spreading of insecticides, defoliants, fertilizers, etc.
The method according to the invention will be described hereinafter, showing an example of embodiment of the said device.
As the method is based on a difference in dampness between the ground, with or without buried objects, it is applicable to all grounds not having dense vegetation, except in the case of rain or snow (where there is water satu- ration and a zero humidit}- gradient). For the best detecting conditions, a day two or three days after the rain, at the beginning of a sunny period, for example, will be chosen. The basic contents of the indicator is a powdered bentonite clay, with a characteristic light ochre colour when it is dry (or, even, Montmorillonite or Illite, etc.) The hygrosensitive colouring product (s) are then mixed into that clay in a proportion of a few grammes of colouring product per kilogram of clay, that concentration vary-ing according to the operating conditions and according to the colouring product used* That mixture is spread on the ground to be scanned in a proportion of about 100 grammes of product per square metre, no particular precaution being required with respect to the spreading method and with respect to the thickness of the layer spread, providing that it be continuous.
The colouring products which may be used are numerous; for example, the following may be quoted: Rhoda ine F. B. (manufacturer B. A. S. F.) in a proportion of 1.5 g per kilogram of clay; Naphtol Green Bluish (manufacturer Kodak Eastman) in a proportion of 5 g per kilogram of clay; Fluorescein Disodium Salt (manufacturer Kodak Eastman) in a proportion of 1.5 to 5 g per kilogram of clay; Eosin Yellowish (manufacturer Kodak Eastman) in a proportion of 1,5 to 5 g per kilogram of clay; Ta rabromophenolsulphonephtelein (Bromophenol Blue) (manufacturer Kodak Eastman) in a proportion of 1.5 to 5 g per kilogram of clay.
They may be used pure or mixed.
In certain atmospheric conditions, a salt such as calcium chloride, for example, in powder form, is added. It may be either mixed with the clay and colouring product or spread on the ground independently.
Then, after a period in the order of 5 to 10 mi-nutes, the ochre colour of the spread mixture becomes modified very noticeably and, according to the colouring products used, there appears a very clear contrast in colour and brilliancy, with a light spot (showing the buried object) surrounded by a dark-coloured surface, showing, so to speak, the outline of buried objects or structures, on the surface of the. ground. The clearness of the shadow obtained depends obviously, on the lateral diffusion of the water vapour gradient above the buried object. Generally, it should be remembered that the "shadow" is clear when the buried object or structure is at a depth of less than its smallest horizontal dimension, or equal thereto.
Thus, for example, an explosive mine having a radius of 20 cm appears with a clear outline if it is at a depth of 10 cm; at a depth of 20 cm, what is distinguished is no longer a circle, but an irregular spot; in the case of several mines arranged in a geometrical pattern (this always being the case), the field is nevertheless easily detected because of its geometrical structure.
Thus, for example, an underground structure of one metre by one metre appears clearly with its shape un-der 50 cm of ground; at a greater depth, it is possible to distinguish underground ruins by the appearance of a regular texture.
The shades thus brought to light remain visible for several days, if there is no rain, etc., and subse-quently disappear progressively. One interesting particularity resides in the fact that the detection marks may reappear after rain. The ground becomes completely red, for Rhodamine, for example and after a few hours, when a humidity gradient has again formed (ground damp or dry), the objects reappear.
The method described according to the invention may, in a general way, be used for detecting any buried object or structure causing a barrier effect with respect to the rising movement of the water, such as the detecting of explosive mines, the detecting of buried piping, assistance in archaeological excavations, detecting of the discontinuity of ground, etc. As this method is an overall method, it may be used for locating objects or structures which are being searched for without knowing where they are: the low cost of this method and the applying thereof by air are then essential factors.

Claims (3)

44554/2 CLAIMS.
1. ^ Method for detection of underground objects or structures, characterised in that a thin layer of a mixture of products is spread on a ground surface, said thin layer having a sub-layer of a clay substance which is used for trapping the water vapour at the surface of the ground and for defining a threshold humidity concentration; said thin layer having another substance, which is a colouring product sensitive to water which dif used and reacts with said layer thereby to cause a visual contrast in colour and brilliancy between the ground in which the object or the structure is constituted and the surrounding ground,
2. Method according to claim 1, characterized in that to the first product:, namely, clay, is abided another^ product, for example a salt consisting of a chloride such as calcium chloride or sodium chloride, enabling the retention capacity of water by the first product, namely, clay, to be modulated.
3. Method according to claim 1 or 2, characterized in that tiie first product, namely, clay, consists of bentonite, Montmorillonite clay, Illite, or a mixture of two or more of these substances. ! Method according to claims 1, 2 or 3 , characterized in that the colouring product consists of a colouring agent such as Rhodamine FB, Naphtol Green Bluish or other synthetic organic colouring agents or a mixture of two or more of those products.
IL44554A 1973-04-03 1974-04-02 Method for the detection of underground objects IL44554A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7312738A FR2224767A1 (en) 1973-04-03 1973-04-03 Detection of buried objects - using dyes mixed with clay spread over the ground

Publications (2)

Publication Number Publication Date
IL44554A0 IL44554A0 (en) 1974-07-31
IL44554A true IL44554A (en) 1977-02-28

Family

ID=9117651

Family Applications (1)

Application Number Title Priority Date Filing Date
IL44554A IL44554A (en) 1973-04-03 1974-04-02 Method for the detection of underground objects

Country Status (2)

Country Link
FR (1) FR2224767A1 (en)
IL (1) IL44554A (en)

Also Published As

Publication number Publication date
IL44554A0 (en) 1974-07-31
FR2224767A1 (en) 1974-10-31
FR2224767B3 (en) 1976-03-26

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