Tunnelling - Science topic

Rida Bensailaa I will recommend you to please study these ABAQUS files to have a better understanding of How the practicall implementation is done for the CONWEP loading; http://abaqusdocs.eait.uq.edu.au/v6.11/books/ver/default.htm?startat=ch03s09abv220.html

Rodney Bartlett

Dear Professor Barlett,

Thank you for your interesting question.

As far as I am aware Josephson himself did not think of it in terms of "tunnelling particles." I think he had a deeper understanding, although the mathematics he used was so abstruse and recondite, nobody could understand what he was talking about--- frankly speaking.

He said in one of his dissertations :

" It is clear that intuition is of no great help in understanding the supercurrent as a flow of Cooper pairs "

Cf. also

And

Dear Shafagat Mahmudova

I am very grateful for your kind proposal. I find this information to be helpful.

There are some TBMs in mining projects (I personally I have participated in pre-feasibility studies and it is becoming a more interesting/feasible excavation method in mining access and developments). What to say in Stillwater mine, used for many years now!

According to the following paper, around 100 TBMs have been used in mining projects (2016) but those are already published, it might be presumed a few more. Obviously, if we compare with civil tunnels, the difference is significant.

TUST-Challengesandopportunitiesofusingtunnelboringmachinesinmining.pdf

Dear Khezr Mohammadamini,

You can simply convert data obtained from the inclinometer to volume loss.

Best regards

I recommend you to model the umbrella pipes in a cad software, and then import it into MIDAS GTS-NX. It's easier than you think.

There's a video about this in MIDAS' YouTube channel: https://www.youtube.com/watch?v=ZHi_A6aJM88

Hope this helps you.

Bye, Felipe.

Actually i tried but dont know about the calculation like which parameter used and where ?

Please help me out .....

TC304 Engineering Practice of Risk Assessment & Management of the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE) provides a list of open datasets that include data of soil and rock mechanics on its website.

How do we determine increased strain by Ge mole fraction? We may determine Eg (strained)/Eg (unstrained) ratio and mn(strained)/mn(unstrained) ratio where Eg and mn are band gap or effective mass of strained SiGe source TFET. If both these ratio keep on decreasing when plotted against Ge mole fraction, we may determine that a sign of increasing strain. But after a certain Ge mole fraction, if these ratios decrease slightly or remain constant or shift up. strain is not effective. The reason as stated is strong quantum confinement with increasing Ge mole fraction, shifting the ground level and sub band energy levels upward in the conduction band shifting Eg upward and the ratio will not further decrease as a result of this. The effective mass or tunneling mass also increase due to strong quantum confinement inducing non-parabolicity of conduction band minima. So the effective mass ratio of strained and unstrained case will not also keep on decreasing beyond a certain Ge mole fraction signifying strain is not effective.

Sincerely,

Dr. Nabil Shovon Ashraf

Associate Professor

Department of ECE

North South University

Dhaka, Bangladesh.

Thank you very much.

Now a day the numerical analysis offer many simulations of mining technologies used in mining practices. My recommend is if you use sophisticated numerical analysis than check results with adequate in situ measurements.

How you write your first equation for the potential depends on where you set your reference potential: the only measurable parameters in experiments are voltages, which are potential differences. Hence, the notation V_G with index G as subscript is insufficient - it should always by V_GX where X is your reference. What do you choose for X? Units are OK in your equation, as energy in eV divided by the elementary charge gives V.

Dear Dr Saluja

I think this is a very difficult problem and presently can only be tackled by means of some rather rough quantum mechanical approximation.Look up first the Kronig-Penney model and the WKBJ quasi classical approximation to start with and then tunelling in Josephson junctions to get some feeling

about the problem.

best regards

Dikeos Mario

The stimulating question from Rafik and the answers from Neil lead to the need for possible further discussion, because the strongly anisotropic nature of flysch (interbedded, cyclical sandstones and shales with marked strength and stiffness differences) represents a challenge to 'all' rock mass classification methods. It is not necessarily solved by a 'GSI sketch' of an inter-bedded rock (often folded) if the subsequent H-B equations produce an 'isotropic solution' in terms of strength and deformation parameters. If using Q, a strongly anisotropic RQD is needed(probably '0'/10 in one direction) and Jr/Ja may be strongly adverse, likewise SRF when weathered, as the weak shale is a significantly adverse feature. The key question is the most representative value to take for Jn the number of joint sets. Cross-jointing may give the clue, one way or the other.

Hi Rafik Hebib,I would like to advise you that not always, in the problems of foundation and in any case of compressive stresses on schist rocks, can be considered as favorable, it depends on the orientation of the schistosity with respect to that of the solicitation. Regarding the use of classification indexes I suggest you use the GSI and consider an equivalent continuous rock mass. However, if you want to use RMR, you should calculate the compressive strength parameter, either in the laboratory or with the Point Load test, taking into account the orientation of the load with respect to the position of the schistosity.

In no manner any expert on squeezing, but the following observation might be of relevance. In the integrated Qc versus P-wave velocity versus static deformation modulus model that has appeared several times since Barton, 2002, (Figure 4) it is found that a fourth 'parameter' viz. the required support pressure Pr from Barton et al. 1974 is inversely related to the deformation modulus. So very low velocity, and very low modulus correlate with very high support pressure needs (sounds and is logical?), and very high velocity, and very high moduli correlate with the need for negligible support pressure (also logical).

I have to say some surprising answers - for me at least! I have never used more than 'free' brain-power/'free' experience-power to estimate RQD from imaginary scan-lines, But if RQD is available from drilling can use this. But remember RQD is an oriented factor (and a bell-shaped central RQD distribution corresponds quite well to Q-class 1 to 4 - based on 40 km of core logging at a mine. Experience is the key, and practice along a road cutting is a good idea. One respondent stated: ' Proper design of a support system should be based on proper numerical analysis based on geomechanical parameters derived by in situ and laboratory tests'. In this connection I wonder what 'proper' is implied? Hopefully not continuum or crude GSI based work. Remember: a posteriori is always going to be much more reliable than a priori - as for so much of the colourful analyses seen in the last 10-20 years. Instead of unchecked-by-originators 'Q-manual' recommendation given by someone, try - and here a biased advice - Barton and Grimstad, 2014 illustrated guide to Q, (see Rg) with lots of example-logging of cores, exposures and tunnels using good photos.

Pål, you can fins some of the most common minerals in table 10 of the following article:

Macias, F.J., Dahl, F. & Bruland, A. (2016). New Rock Abrasivity Test Method for Tool Life Assessments on Hard Rock Tunnel Boring: The Rolling Indentation Abrasion Test (RIAT)

Rock Mech Rock Eng (2016) 49: 1679. https://doi.org/10.1007/s00603-015-0854-3

In my opinion the only way to get consistent answers in QM in terms of paths is via Feynman's formalism: consider all possible paths, and sum up the corresponding amplitudes. Once your detectors are in given positions, you sum up the amplitudes of getting to these detectors, and square that sum. The fact, for example, that two particles cannot simultaneously reach P1' and P2' is related to the fact that the paths carrying both particles there interfere destructively. This, however, has nothing to do with the total amplitude of reaching detectors D1 and D2, since there is no reason for the particle to go through P2'.

Of course, I realise you know all this. My point is that it is probably difficult, most likely impossible, to obtain a ``reasonable'' picture of QM in classical terms, where trajectories are well-defined and satisfy logical requirements.

In fact, I believe there are Bell type inequalities involving momentum and position whenever the Wigner function of the corresponding state has negative values.

I believe your insistence on a classical picture is understandable, but I reiterate my doubts: I do not believe such a picture can be made to fit the facts.

Dear Anthony Nash,

I like to add to the well taken comments above, some general cosiderations: 1. If you want to draw an energy landscape versus a reaction coordinate, you should keep in mind, that you need to incorporate a correlated proton motion involving many protons, possibly steered by low frequency modes.2.The relaxation will always overestimate the local relaxation and underestimate the long range coupling effects between protons, which you need to lower the activation free energy for a reaction path in absence of an ensime.

Best regards,

Sghart F. Fischer   

Attached some of the reports of ITA on TBMs, as well as some others. You might find some other reports in the ITA webpage (https://www.ita-aites.org/) 

Hi Maheswara,

Do you want model the both temporary and permanent lining in simultaneously? I don't suggest you Plaxis software for this purpose, and even with volume element it's not accurate enough. I suggest you use another software such as FLAC.

Maybe you find these to papers interesting:

DOI: 10.1021/om0209632

This is an example on how tunnelling indeed explains the experimentally observed rates of some metathesis relations.

DOI: 10.1021/j150606a003

This second paper develops a general theory to calculate the transmission coefficients.

Hope it helps :-)

Hello, in order to design tunneling devices, you first understand

the potential discontinuities at the junction interface formed by different semiconductor materials. This is not related with the type. Thus, direct or indirect, this is not important.

The tunneling current is determined by the effective masses and barrier width.

What kind of linear trend are you referring to and why, a priori, do you expect so? Which are the relevant features of your device and, last but not least, which model/process do you wish to implement?

Some years ago, we used similar techniques for intra-arterial BP recording in conscious unrestrained and untethered rats. Details of our technique can be found in the following publications: Am J Physiol Heart Circ Physiol 275:H1290-H1297, 1998 and Am J Physiol Heart Circ Physiol 292:H2506-H2512, 2007. In particular, we constructed polyethylene catheters [a PE-10 (2 cm length, 0.28 mm ID, 0.61 mm OD; Clay Adams, Parsippany, NJ) fused to a PE-50 (15 cm length, 0.58 mm ID, 0.96 mm OD; Guerbet, Louvres, France)] filled with heparinized 0.9% NaCl (50 U/ml). The catheter was inserted into the lower abdominal aorta via the left femoral artery to record distal (peripheral) aortic BP. The catheter was tunneled subcutaneously under the skin of the back to exit between the scapulae and was plugged with a short piece of stainless steel wire. After 24 h of rest, the catheter was attached to another PE-50 (15–20 cm). At least 2 limits must be highlighted: 1) whatever the diameter of the catheter, its tends to be obstructed with coated blood even if its filled with heparinised physiological saline. 2) Catheterisation of femoral artery leads to a heavier surgery than catheterizing carotid artery, as one have to tunnel the catheter through all the length of the back of the rat. Nowadays, the best way to record arterial BP is using telemetry, although this technique is very expensive.

Hi Saleh

you can find some information in below references:

1- Bruland, A. (2000). Hard rock tunnel boring.

2- Maidl, B., Schmid, L., Ritz, W., & Herrenknecht, M . Hardrock tunnel boring machines. John Wiley & Sons.

3- Kolymbas, D. (2005). Tunnelling and tunnel mechanics: a rational approach to tunnelling. Springer Science & Business Media.

Hi Mr Sedaghati

You can find good information in these researches

and 

kind regards Saleh

It is depend on design factors and structure types.For cavern you should do long term analysis as well as permanent and temporary ..etc analysis ,For structure like metro tunnels seismic analysis is needed too.But you may do temporary analysis for some mining excavations with low life time.

As the former ( above) said, just using the Si(111) of Au(111) surfaces for STM calibration should be more proper and standard.

Hi Johnatan,

I know it's kind of hard to get those kind of information from books. I guess you can find more information in national or international congress and conference proceedings, where lots of consultant companies share the work they developed. As an example, you can see two papers from a company I worked (in portuguese):

If you're looking for larger information databases, maybe it's better to search for the original papers about the RMR and Q, I guess they must present some information. A simple search for RMR and Q in scientific search engines (ScienceDirect, for example) can lead you as well to several papers where some information is shared, like this one:

Cheers, Francisco

Hello Pejvak,

I am unaware of quantum tunnelling of information via the time dimension, but quantum entanglement can influence traditional quantum tunnelling significantly. In particular, quantum entanglement can enhance or suppress quantum tunnelling under certain conditions: http://www.sciencedirect.com/science/article/pii/S0375960105003324

I hope you find this paper useful.

Best regards,

Alex

The SRF is not intended for conditions with mining-induced stress change. It has not been developed or tested for such conditions.  Thus, if nearby tunnelling significantly affects the behaviour of a tunnel. Q and SRF are not directly applicable. As a general statement it can be said that it must be higher but no guidance is available on how much higher.

Numerical modelling may assist in understanding the related stress path which then can be used to asses whether Q is or is not applicable.