Which of the following is a characteristic of general shear failure?

Question

Examoogle · Accepted Answer

Option C: Bulging of shearing mass of soil

Explanation & Concepts:
General shear failure occurs in dense sand or stiff clay under a shallow foundation when the soil fails along a continuous and well-defined failure surface that extends up to the ground level. A key characteristic of general shear failure is the noticeable bulging of the shearing mass of soil adjacent to the footing, accompanied by a sudden catastrophic collapse and visible tilting of the structure.

Working Principle: When a load is applied to a foundation resting on dense or stiff soil, the soil deforms elastically until the maximum shear strength is reached along a defined failure plane. Upon reaching ultimate bearing capacity, a wedge of soil beneath the footing moves downward, forcing the adjacent zones to move laterally and upward, causing pronounced heave or bulging at the ground surface.

Key Formulas: $q_{u} = c N_c + q N_q + 0.5 \gamma B N_gamma$ — Terzaghi's ultimate bearing capacity equation for general shear failure; $D_r > 70\%$ — Relative density condition for dense sand where general shear failure typically occurs

Key Points: General shear failure occurs in soils of low compressibility, such as dense sand ($D_r > 70\%$) and stiff clay ($N_{SPT} > 30$).; It is characterized by a clear ultimate failure point on the load-settlement curve and sudden catastrophic failure with structural tilting.; A continuous shear plane forms and extends all the way to the ground surface, resulting in prominent surface bulging/heaving.

Additional Info: Option A is incorrect because soil compressibility is a major characteristic of local and punching shear failures in loose or compressible soils, not general shear failure.. Option B is true regarding the sudden nature of general shear failure, but Option C is a distinct and definitive physical characteristic (bulging of shearing mass), making Option C the specified correct answer.

Answer: C is correct — General shear failure involves the lateral displacement of soil along a continuous slip surface, which forces the adjacent soil mass to bulge upward at the ground surface.

Exam Tip: For GATE and ESE exams, remember that for local shear failure, shear parameters are reduced ($c' = \frac{2}{3}c$ and $	an\phi' = \frac{2}{3}	an\phi$), whereas general shear failure uses full shear parameter values.

Examoogle · Answer

Option A: Failure is accompanied by compressibility of soil

Examoogle · Answer

Option B: Failure is sudden

Examoogle · Answer

Option D: All of the mentioned

Feature	General Shear Failure	Punching Shear Failure
Soil Type & Density	Dense Sand ( $D_r > 70\%$ ) / Stiff Clay	Loose Sand ( $D_r < 30\%$ ) / Soft Clay
Failure Surface	Well-defined, extends to ground surface	Poorly defined, localized under footing
Surface Bulging/Heave	Significant bulging on sides of footing	No bulging observed at ground surface
Failure Nature	Sudden, accompanied by tilting of footing	Gradual, characterized by deep vertical penetration

Correct Answer

Discussion (0)

Correct Answer

Related Questions

Discussion (0)