engineering

Q-system (geotechnical engineering)

Q-system (geotechnical engineering) is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Q-system (geotechnical engineering) rather than just read about it. In short: For the linguistics formalism, see Q-systems. For the genetic method, see Q-system (genetics).

Key takeaways

Q-system (geotechnical engineering) belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Q-system (geotechnical engineering) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Q-system (geotechnical engineering) from memory before moving on to harder problems.

Reference excerpt

For the linguistics formalism, see Q-systems. For the genetic method, see Q-system (genetics). The Q-system for rock mass classification is developed by Barton, Lien, and Lunde. It expresses the quality of the rock mass in the so-called Q-value, on which design are based and support recommendations for underground excavations. The Q-value is determined with

Q = R Q D J n × J r J a × J w S R F {\displaystyle Q={\frac {RQD}{J_{n}}}\times {\frac {J_{r}}{J_{a}}}\times {\frac {J_{w}}{SRF}}}

The first term RQD (Rock Quality Designation) divided by Jn (joint set number) is related to the size of the intact rock blocks in the rock mass. The second term Jr (joint roughness number) divided by Ja (joint alteration number) is related to the shear strength along the discontinuity planes and the third term Jw (joint water parameter) divided by SRF (stress reduction factor) is related to the stress environment on the intact rock blocks and discontinuities around the underground excavation. A multiplication of the three terms results in the Q parameter, which can range between 0.001 for an exceptionally poor to 1000 for an exceptionally good rock mass. The numerical values of the class boundaries for the different rock mass qualities are subdivisions of the Q range on a logarithmic scale. The Q-value determines the quality of the rock mass, but the support of an underground excavation is based not only on the Q-value but is also determined by the different terms in the above equation. This leads to a very extensive list of classes for support recommendations.

See also Rock Structure Rating Hoek-Brown failure criterion Rock mass rating

References

Further reading Bieniawski, Z.T. "Engineering Rock Mass Classifications", John Wiley and Sons, New York, 1989 Hack, H.R.G.K. (25–28 November 2002). "An evaluation of slope stability classification. Keynote Lecture.". In Dinis da Gama, C.; Ribeira e Sousa, L. (eds.). Proc. ISRM EUROCK’2002. Funchal, Madeira, Portugal: Sociedade Portuguesa de Geotecnia, Lisboa, Portugal. pp. 3–32. ISBN 972-98781-2-9. Pantelidis, L (2009). "Rock slope stability assessment through rock mass classification systems", International Journal of Rock Mechanics and Mining Sciences, 46(2), (315–325). Palmstrom, A.; Broch, E. (2006). "Use and misuse of rock mass classification systems with particular reference to the Q-system". Tunnelling and Underground Space Technology. 21 (6): 575–593. Bibcode:2006TUSTI..21..575P. doi:10.1016/j.tust.2005.10.005.

External links Q-system calculator

Worked examples

Example 1 — a first encounter with Q-system (geotechnical engineering)

Start with the simplest possible case. Write down what Q-system (geotechnical engineering) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Q-system (geotechnical engineering) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Q-system (geotechnical engineering) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Q-system (geotechnical engineering)

In research: Q-system (geotechnical engineering) appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Q-system (geotechnical engineering) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Q-system (geotechnical engineering) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Rock mass classification, so understanding it makes those chapters shorter.
In everyday life: Look for Q-system (geotechnical engineering) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Q-system (geotechnical engineering) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Q-system (geotechnical engineering) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Q-system (geotechnical engineering) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Q-system (geotechnical engineering) in simple terms?

For the linguistics formalism, see Q-systems. For the genetic method, see Q-system (genetics).

Why does Q-system (geotechnical engineering) matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Q-system (geotechnical engineering)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Q-system (geotechnical engineering).