671017.pdf

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Figure 25: The damaged zone under different principal elastic directions (red arrows represent the flow velocity vector).

As shown inFigure 24, the flow velocity in scenario where
휃=0∘ isinthelowestlevel.Thereasonisthatthejoint
planeinthisscenarioishorizontallydistributedandthe
compressive stress leads to the decrease of permeability.
When angle of joint plane increases to 30∘,flowvelocities
above both roadways increase and Roadway I has a more
higher velocity than Roadway II. The scenario where휃=60∘
has similar performance. However, when the joint plane is
vertically distributed, flow velocity above Roadway I is lower

than that where휃=60∘.Theflowvelocityinthecasewhere

joints are vertically or horizontally distributed is symmetric.

4.7.2. Damage Zone.The effect of joint plane angle on the

damage zone is illustrated by using the Hoffman anisotropic

strength criterion as shown in (23). The damage zones in

different angles of joint planes are shown inFigure 25and

couldbeanindextovisualizethepotentialfailuremodeof

the roadway.