Quiz 3 Flashcards
The study of the properties, mechanical behavior of rock, and the nature of stresses
underground.
a. geotechnics b. soil mechanics c. rock mechanics d. engineering geology
c
. The term used to describe the intact rock between discontinuities; a hand specimen or a piece of drill core examined in the laboratory might represent it.
a. rock material b. rock mass c. boulder d. intrusive.
a
. The total in-situ medium containing structural features.
a. rock material b. orebody c. rock mass d. deposit
c
. A rock mass parameter that quantifies discontinuity by the ratio of the lengths of the
individual pieces of core recovered in a drill run, having lengths of 10 cm or greater, and the
total length of drill run.
a. rock mass rating b. percent core recovery c. fracture spacing d. RQD
d
. Method of representing and analyzing the three-dimensional relations between planes and lines on a two dimensional diagram.
a. hemispherical projections b. orthographic projection
b. plane projection d. isometric projection
a
- The maximum stress that the rock material can sustain under a given set of condition.
a. bearing capacity b. hardness c. peak strength d. malleability
c
- The stress which governs the gross mechanical response of a porous material.
a. normal stress b. thermal stress c. shear stress d. effective stress
d
- The stress-reduction effect given by one opening to another opening that is below and parallel
to it.
a. dome effect b. stress shadow c. shielding effect d. pressure arch.
c
- The stress existing in a rock mass before the excavation of an opening.
a. in-situ stress b. tangential stress c. shear stress d. induced stress
a
. The stress that is deflected to the virgin blocks or blocks adjacent to the opening. The stress
was formerly carried by the block that has been extracted in creating the opening.
a. in-situ stress b. abutment stress c. virgin stress d. principal stress
b
- Select the main reason why rock mechanics should be separated from classical engineering
mechanics:
a. rock mechanics has more inherent complexities compared with classical mechanics.
b. in classical mechanics, the designer has a wider option for structural materials while the
rock mechanics engineer does not.
c. in rock mechanics, the structural element, which is rock, can still perform its
function even if the element has failed, while in classical mechanics the load
bearing capacity drops down to zero.
d. rock is weakest in tension as opposed to structural steel in classical mechanics.
c
- The rock in which the ore body is enclosed.
a. quartz b. vein c. country rock d. outcrop
c
- Why do rocks often fail at the crown of a tunnel?
a. Because of tensile stresses.
b. They fail due to high vertical stresses.
c. Due to high horizontal stresses.
d. Because of shear stresses.
a
- Why are smaller rock samples, when tested in the laboratory, stronger than larger ones?
a. Smaller samples appear stronger due to laboratory equipment’s rigidity.
b. Smaller samples contains less of the in-situ rock’s naturalfractures.
c. Laboratory procedures always follow the strain-controlled, and not the stress-controlled, testing.
d. Smaller specimens are made stronger by the effect of friction offered by the steel
platens.
b
- Hydrostatic stress field in rock mechanics means:
a. forces exerted by fluids at rest;
b. the condition in a 2-dimensional stress field wherein the horizontal stress is equal
to the vertical stress;
c. stress condition created by abnormally high groundwater level;
d. a zone of confined water table
b
- Stress distributions around single openings in elastic rock subject to biaxial stress field are:
a. Dependent on the depth of the opening.
b. Dependent on the size of the opening.
c. Dependent on the elastic properties of the rock.
d. Independent of the elastic properties of the rock.
d
What magnitude of stress is carried by a pillar in a 20m x 20m room-and-pillar section of a
75% extraction with square pillars measuring 5m x 5m as in the sketch. Assume that the
mining depth is 80m and the unit weight of the overburden is 0.025 MN/m3
.
a. 100 MPa, b. 150 MPa, c. 200 MPa, d. 250 MPa.
c
