Struktur Geologi
Budhi Kuswan Susilo, ST.MT
JENIS STRUKTUR
LIPATAN (FOLDS)
SESAR/PATAHAN (FAULTS)
REKAHAN (JOINTS/FRACTURES)
LIPATAN
(folds)
MENGUKUR
GEOMETRI LIPATAN
Strike and Dip
Azimuth of horizontal across slope (q) indicates
which way plane faces. Dip (f) indicates how
steeply the plane is inclined
Measuring
strike by
touching
Measuring dip
by touching
Dip of the fold
Axial surface
Or plunge of
The fold axis
Dip of hinge surface Plunge of hinge line (i.e.,
(i.e., attitude of axial attitude of fold axis)
plane)
0o
Recumbent fold
Horizontal fold
1-10o
Recumbent fold
Sub-horizontal fold
10-30o
Gently inclined fold
Gently plunging fold
30-60o
Moderately inclined fold
Moderately plunging fold
60-80o
Steeply inclined fold
Steeply plunging fold
80-89o
Upright fold
Sub-vertical fold
90o
Upright fold
Vertical fold
SESAR
(faults)
REKAHAN
(fractures)
Extension
fracture =
mode I fracture
Relative
motion : tegak
lurus terhadap
fracture walls
Shear fractures
Relative motion : parallel terhadap bidang
Mode II Shear
Fracture
Motion : sliding
motion tegak lurus
terhadap tepi kekar
Mode III Shear
fracture
Motion : sliding motion
parallel terhadap
tepi kekar
MAX. P. S.
EJ
RJ
SJ
SJ
MIN.P.S.
INT. P. S.
Dynamic (stress) analysis of joint system:
MAX. P. S. = Maximum Principal Stress
INT. P. S. = Intermediate Principal Stress
MIN. P. S. = Minimum Principal Stress
SJ = Shear Joint
EJ = Extension Joint
RJ = Release Joint
Joints: factures without visible displacement, induced
by tensile stress
Multiple sets of joints
joint surfaces
Sheet-like
joints in
plutons due to
cooling.
Why do we need
to be concerned
about the
orientation of
surface structures?
How were decisions
made about which
blocks to stabilize
by bolts?
Why do we need to be concerned about the
underground location of bedrock structures?
The location of
underground
structures must be
anticipated in
engineering design.
We do need it here.
Queen’sTunnel, C. Merguerian, 1999
Akhir Kuliah
Struktur Geologi