ASBOG Engineering Geology 4

Question 1

Karst terrain presents which primary engineering hazard for foundation design?

Accepted Answer

Sudden sinkhole collapse due to dissolution cavities

Answer

Dissolution of soluble rock (limestone, dolomite) by groundwater creates subsurface cavities that can collapse suddenly, causing sinkholes beneath structures.

Question 2

The Mohr-Coulomb failure criterion for a rock joint is expressed as:

Accepted Answer

τ = c + σn tan φ

Answer

The Mohr-Coulomb criterion states that shear stress at failure (τ) equals cohesion (c) plus normal stress (σn) times the tangent of friction angle (φ).

Question 3

Which condition best describes an artesian aquifer?

Accepted Answer

Groundwater is confined under pressure above the top of the aquifer

Answer

An artesian (confined) aquifer is bounded above by an aquitard and contains water under pressure greater than atmospheric, so the piezometric level rises above the top of the aquifer.

Question 4

A geologist maps a fault plane with orientation 060/45 NW (strike/dip). The apparent dip seen in a north-south cross section is:

Accepted Answer

Less than the true dip of 45°

Answer

Apparent dip is always less than or equal to true dip; it equals true dip only when the cross section is perpendicular to strike, and decreases as the section obliquity increases.

Question 5

The primary purpose of a piezometer installed in a slope is to:

Accepted Answer

Monitor pore water pressure to assess stability

Answer

Piezometers measure pore water pressure, which is a critical parameter in the Mohr-Coulomb effective stress equation used for slope stability calculations.

ASBOG - Association of State Boards of Geology Practice Test

ASBOG - Association of State Boards of Geology Practice Test

ASBOG Engineering Geology 4