joints are slightly rough$/$weathered and continuous, with separation distance

between the joint surfaces ranging between $1\mathrm{.}0-1\mathrm{.}3mm.$

Joint #$2$ strikes $45$ to long axis of planned excavation, dips $20$ and repeats at

intervals of approximately $0\mathrm{.}3m$; surface of these joints are very rough and

discontinuous with separation between surfaces being

Stress $/$ Water Conditions:

Maximum ground stress components are expected to be horizontally directed, of

magnitude less than $1\mathrm{.}5$ times vertical stress component, and uniformly distributed

horizontally at the site of excavation; minimal water flow $(<mn>5</mn><mfrac><mrow><mi>L</mi></mrow><mrow><mi>m</mi></mrow></mfrac><mi>i</mi><mi>n</mi>$ at low

pressure$)$ from the rock is anticipated.An underground tunnel is planned to be excavated in rock. This excavation is to be

developed initially on the basis of diamond drill core data retrieved by remote drilling, as

no site development currently has taken place. Based upon information which is

provided:

a$.$ Determine the RQD for the core shown;

b$.$ Determine the RMR for the rock mass at the proposed development site;

c$.$ Determine the limiting excavation dimensions $($maximum and minimum$)$;

d$.$ Determine the unsupported stand$-$up times for these excavation dimensions and

the range of rock reinforcement that would be necessary for the excavation $($over

the dimension ranges selected$).$

Given:

Core Recovery Data: As illustrated in Figure of core box sketch

$($total length of core recovered $=3\mathrm{.}0m).$

Core Strength Data:

Joint Conditions:

Two joint families identified:

See info on screenshots