physics

Shear strength (discontinuity)

Shear strength (discontinuity) is a physics 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 Shear strength (discontinuity) rather than just read about it. In short: The shear strength of a discontinuity in a soil or rock mass may have a strong impact on the mechanical behavior of a soil or rock mass. The shear strength of a discontinuity is often considerably lower than the shear strength of the blocks of intact material in between the discontinuities, and therefore influences, for example, tunnel, foundation, or slope engineering, but also the stability of natural slopes.

Key takeaways

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

Reference excerpt

The shear strength of a discontinuity in a soil or rock mass may have a strong impact on the mechanical behavior of a soil or rock mass. The shear strength of a discontinuity is often considerably lower than the shear strength of the blocks of intact material in between the discontinuities, and therefore influences, for example, tunnel, foundation, or slope engineering, but also the stability of natural slopes. Many slopes, natural and man-made, fail due to a low shear strength of discontinuities in the soil or rock mass in the slope. The deformation characteristics of a soil or rock mass are also influenced by the shear strength of the discontinuities. For example, the modulus of deformation is reduced, and the deformation becomes plastic (i.e. non-reversible deformation on reduction of stress) rather than elastic (i.e. reversible deformation). This may cause, for example, larger settlement of foundations, which is also permanent even if the load is only temporary. Furthermore, the shear strength of discontinuities influences the stress distribution in a soil or rock mass.

Shear strength The shear strength along a discontinuity in a soil or rock mass in geotechnical engineering is governed by the persistence of the discontinuity, roughness of discontinuity surfaces, infill material in the discontinuity, presence and pressure of gasses and fluids (e.g. water, oil), and possible solution (e.g. karst) and cementation along the discontinuity. Further the shear strength is dependent on whether the discontinuity has moved before in the geological history (i.e. are the asperities on opposing walls of the discontinuity fitting or non-fitting, or have the asperities been sheared off).

Determination shear strength Only for simple models of discontinuities the shear strength can be analytically calculated. For real discontinuities no analytical calculation method exists. Testing on various scales in the laboratory or in the field, or empirical calculations based on characterizing the discontinuity are used to establish the shear strength.

Discontinuity shear strength tests Direct shear test or (Golder) shearbox test Punch-through shear test Tilt test (geotechnical engineering) Triaxial test

Empirical calculations based on characterization Barton-Bandis shear criterion Sliding criterion

References

Worked examples

Example 1 — a first encounter with Shear strength (discontinuity)

Start with the simplest possible case. Write down what Shear strength (discontinuity) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, 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 Shear strength (discontinuity) 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 Shear strength (discontinuity) 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 Shear strength (discontinuity)

In research: Shear strength (discontinuity) appears in physics 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 Shear strength (discontinuity) 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: Shear strength (discontinuity) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Mining engineering, Shear strength, Soil mechanics, so understanding it makes those chapters shorter.
In everyday life: Look for Shear strength (discontinuity) 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Shear strength (discontinuity)” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Shear strength (discontinuity) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Shear strength (discontinuity) 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 Shear strength (discontinuity) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Shear strength (discontinuity) in simple terms?

Why does Shear strength (discontinuity) matter?

Because it connects several physics 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 Shear strength (discontinuity)?

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 Shear strength (discontinuity).