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- since 1996 -
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Technical Discussions
Nibi
Nibi
06:11 Mar-04-2015
scope of ultrasonic detection in soil

Can we use ultrasonic frequency signal for find the depth of the soil cavity/tunnel. If we use 40KHz ultrasonic signal how much depth it can penetrate. Could you please give me some suggestions.

 
 Reply 
 
John Norman
Consultant, owner of business
NTS Ultrasonics Pty Ltd, Australia, Joined Oct 2012, 116

John Norman

Consultant, owner of business
NTS Ultrasonics Pty Ltd,
Australia,
Joined Oct 2012
116
10:25 Mar-04-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi at 06:11 Mar-04-2015 (Opening).

Hi Nibi.

My best answer is "maybe". I have an old photocopied reference here titled "Detection of underground remains by impulse sound" by K. Matsuda and K. Ozawa. I have no idea of the date or journal. In that they attempt to detect stone coffins buried in sand up to 3 metres deep. They used 500 Hz, and identify the main problems as the inhomogeneity of the soil and obtaining good impedance matching to the soil.

If you search on the internet you may find other, similar papers, maybe for archeological work, and maybe for locating buried objects like pipes and so on. I seem to recall such papers appearing from time to time, but I don't have any other direct references.

I do have a paper on using sound for measuring pavement thickness, and once again, impedance matching is the issue.

More generally, you can find papers on the transmission of ultrasound in soils and sediments, sometimes using a thing called an impedance tube. Some of these papers might give you a few useful ideas.

Soil moisture seems to have a big influence on sound transmission.

If I had the job of designing something for work in soil, I would probably start by working in the 20 KHz to 40 KHz frequency range (because I already have equipment for that) and look at some sort of coded pulse approach to cope with the high attenuation, and then spend a lot of effort on the transducer design to get the impedance matching sorted out.

My answer probably doesn't help much, but don't give up.

Regards
John Norman

 
 Reply 
 
Rick Lopez
R & D,
John Deere - Moline Technology Innovation Center, USA, Joined Jul 2011, 190

Rick Lopez

R & D,
John Deere - Moline Technology Innovation Center,
USA,
Joined Jul 2011
190
15:54 Mar-04-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi at 06:11 Mar-04-2015 (Opening).

Given the many uncertainties, maybe this would be a better application for ground-penetrating radar?

 
 Reply 
 
John Norman
Consultant, owner of business
NTS Ultrasonics Pty Ltd, Australia, Joined Oct 2012, 116

John Norman

Consultant, owner of business
NTS Ultrasonics Pty Ltd,
Australia,
Joined Oct 2012
116
01:20 Mar-05-2015
Re: scope of ultrasonic detection in soil
In Reply to Rick Lopez at 15:54 Mar-04-2015 .

Good point, Rick. I should have mentioned GPR in my answer.

However, maybe Nibi has looked into this and found it unsuitable due to the properties of the soil. I know that here in Western Australia, where I am based, GPR is difficult to use in some areas due to the properties of the soil, around Kalgoorlie, for example. This is our main gold mining area and the soil is highly mineralized and not GPR friendly.

Regards
John Norman

 
 Reply 
 
Luan T. Nguyen
Germany, Joined Feb 2015, 1

Luan T. Nguyen

Germany,
Joined Feb 2015
1
09:47 Mar-05-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi at 06:11 Mar-04-2015 (Opening).

Much lower frequency of the source is more suitable for good penetration depth. Low frequency seismic tomography is successful for such near surface identification. See, for example, the online available report 'Detection of Sinkholes or Anomalies Using Full Seismic Wave Fields' by McVay and Tran in which underground structure in meters range below the surface can be identified.

 
 Reply 
 
Nibi K V
Nibi K V
09:40 Mar-19-2015
Re: scope of ultrasonic detection in soil
In Reply to John Norman at 10:25 Mar-04-2015 .

Thank You all for your valuable suggestions.
If I use an ultrasonic sensor for the transmission the major problems are
*Coupling between transmitter/sensor and medium
*Velocity of the soil varies for different soil type
*Echo signal intensity

Can I reduce the problems by using a power amplifier for transmitter ???



 
 Reply 
 
John Norman
Consultant, owner of business
NTS Ultrasonics Pty Ltd, Australia, Joined Oct 2012, 116

John Norman

Consultant, owner of business
NTS Ultrasonics Pty Ltd,
Australia,
Joined Oct 2012
116
10:00 Mar-19-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi K V at 09:40 Mar-19-2015 .

Hi Nibi,

You probably will need to use a power amplifier. I don't think any sort of conventional pulser circuit is going to be useful. Your transmit signal will probably need to be something like a gated sine wave, or a chirp, or a coded pulse.

However, like Rick suggested, ground penetrating radar is more likely to be successful unless the soil is unsuitable.

What depth are you hoping to detect things at, and are they large or small things? Do they have a specific shape?

Regards
John Norman

 
 Reply 
 
Nibi K V
Nibi K V
05:04 Mar-20-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi at 06:11 Mar-04-2015 (Opening).

Thank You John Norman
I planned to detect illegal underground tunnels . The tunnels are made of any materials. The depth range up-to 20m.

 
 Reply 
 
John Norman
Consultant, owner of business
NTS Ultrasonics Pty Ltd, Australia, Joined Oct 2012, 116

John Norman

Consultant, owner of business
NTS Ultrasonics Pty Ltd,
Australia,
Joined Oct 2012
116
05:45 Mar-20-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi K V at 05:04 Mar-20-2015 .

Hi Nibi.

Tunnels sounds more like a ground penetrating radar application and some very good systems are available commercially. Have you considered ground penetrating radar?

Regards
John Norman

 
 Reply 
 
Nibi K V
Nibi K V
06:22 Mar-26-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi at 06:11 Mar-04-2015 (Opening).

GPR uses EM signals. I want to try this with ultrasonic signals.
Could you please tell me is there any ultrasonic sensor that we can use in soil (to measure Depth). Can I get good result of soil depth if I use a normal ultrasonic sensor (range detector in air) with an ardiuno driver and an amplifier

 
 Reply 
 
John Norman
Consultant, owner of business
NTS Ultrasonics Pty Ltd, Australia, Joined Oct 2012, 116

John Norman

Consultant, owner of business
NTS Ultrasonics Pty Ltd,
Australia,
Joined Oct 2012
116
08:35 Mar-26-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi K V at 06:22 Mar-26-2015 .

Hi Nibi.

Nothing wrong with an Arduino as a signal generator, I guess. I have never used one. I don't know what sort of transducer will do the job, but I am pretty certain a small 40 KHz air ranging transducer will not be suitable. Because of the scattering and attenuation in the soil and the difficulties of coupling the sound into the soil, I think significant power will be required.

As a guide try looking for US patent 5719823 using Google. This patent described a ground penetrating sonar.

Regards
John Norman

 
 Reply 
 
Wieslaw Bicz
Engineering,
PBP Optel sp. z o.o., Poland, Joined Feb 2009, 268

Wieslaw Bicz

Engineering,
PBP Optel sp. z o.o.,
Poland,
Joined Feb 2009
268
12:24 Mar-26-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi K V at 06:22 Mar-26-2015 .

We have made a generator for a project with the goal to detect non metal objects buried in sand. The required power was in this case (for bursts) was significantly higher than 2kW. Special transducers was used and the goal was reached. In other types of ground it should be more difficult and if there are layers with different substances the difficulty is growing. You will surely need very high power, special transducers, very sensitive receiver (special ones) and a very sophisticated signal analysis. Surely many positions of sender and receiver must be used (arrays of) or a scanner.

 
 Reply 
 
Frank Lund
R & D,
United Kingdom, Joined Apr 2005, 222

Frank Lund

R & D,
United Kingdom,
Joined Apr 2005
222
14:38 Mar-26-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi K V at 05:04 Mar-20-2015 .

Archaelogists use techniques such as Ground Resistance mapping, perhaps Ground Resistance Tomography using more ground contacts may be useful.

Use natural radioactivity/cosmic rays to "X-ray" the ground???

Sensitive Geomagnetic survey (proton spin???) may also be useful. There was an article in Everyday Electronics / Practical Electronics on this a few decades ago using bottles of water as the medium having the spin affected by fine changes in magnetic field.

SQUIDs are very sensitive detectors of magnetism (but not on an Arduino sized budget).

 
 Reply 
 
Frank Lund
R & D,
United Kingdom, Joined Apr 2005, 222

Frank Lund

R & D,
United Kingdom,
Joined Apr 2005
222
19:34 Mar-26-2015
Re: scope of ultrasonic detection in soil
As well as giving you (or your intern) exercise, a steel rod stuck into the ground then struck on its upper end by a sledge hammer makes a cheap high energy pulser. Its PRF is rather slower than you might expect an Arduino, PIC or ARM based device to produce.
 
 Reply 
 
Gerald R. Reams
Engineering,
Industry, USA, Joined Aug 2012, 181

Gerald R. Reams

Engineering,
Industry,
USA,
Joined Aug 2012
181
20:01 Mar-26-2015
Re: scope of ultrasonic detection in soil
In Reply to Frank Lund at 19:34 Mar-26-2015 .

When I was young and living in Rural Kentucky, USA an oil company spent a great deal of time and effort driving equipment through the area. I was told that they were seismic mapping the area for potential locations of oil. I do know that many wells were drilled and capped.

Anyone familiar with what this type of exploration? Could it find tunnels?

 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1286

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1286
22:30 Mar-26-2015
Re: scope of ultrasonic detection in soil
In Reply to Gerald R. Reams at 20:01 Mar-26-2015 .

Gerald, I think Rick Lopez's answer is the most useful. What you witnessed in Kentucky was called deep seismic surveys. Effectively they blast a charge of dynamite and record arrival times of the impulses at geophones located along the ground surface at known distances. Indeed, seismic waves are mechanical like ultrasound, but at an upper frequency of 50Hz the wavelengths are many metres long. You would have very poor resolution unless looking for large geologic features like salt domes or ancient river valleys.
To locate voids in the ground (like drainage tiles, caverns in archaeology and wash-out areas under roads), GPR is probably the best option. One of the companies supplying the equipment is in Canada at Sensors and Software (Mississauga, Ontario). http://www.sensoft.ca/Products.aspx
They rent the equipment too.

 
 Reply 
 
John Norman
Consultant, owner of business
NTS Ultrasonics Pty Ltd, Australia, Joined Oct 2012, 116

John Norman

Consultant, owner of business
NTS Ultrasonics Pty Ltd,
Australia,
Joined Oct 2012
116
01:17 Mar-27-2015
Re: scope of ultrasonic detection in soil
In Reply to Nibi K V at 09:40 Mar-19-2015 .

Hi again, Nibi.

I recall reading a paper many years ago describing a "ground sonar" system. The system used separate transmitting and receiving transducers, and it may have used multiple receivers, I don't recall. However, the transmitter was essentially a plate with an area of about 1 sq metres with multiple transducers mounted on one side and fired in parallel. It would be a bit like what is called a diaphragm plate in industrial ultrasonic cleaning. I don't recall, but I guess the individual transducers would be low frequency and probably of the bolted Langevin or Tonpilz type. This transducer assembly would need to be driven at high power, and as Weislaw mentions, a peak power in excess of 2Kw would not be unreasonable.

I think the paper mentioned that the system worked best if water was poured onto the soil before using the sonar.

Is there a reason why you do not want to consider ground penetrating radar? Good systems are available for purchase or hire.

GPR is certainly outside the scope of a typical Arduino project, but then, frankly, so is the ground sonar. If you are looking for an electronics project you can do yourself, the design of the power amplifier will present issues of working with high voltages and currents, with the associated dangers, and the design of the transducers is very specialized.

Regards
John Norman

 
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