The other major constraint will be
the refractor velocity, V2=4187 m/s determined from reverse profiles
on line 1. This constraint is necessary since reverse profiles were
not possible for line 3. As can be seen on Figure 34, the hammer blows
fired broadside into line 3. The location for the source was not arbitrary,
but chosen to be far enough away from all the geophone stations on
line 3 (beyond the cross-over distance for the refraction). The bedrock
refractor was granite, the overburden was silty sand with gravel (Unified
classification SM). Soil testing indicated an internal angle of friction
of . Given that the topographic slope was about
, the in place overburden was judged to be at the angle of repose.
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2018-04-08