classification of joints in geology

1. GEOMETRICAL &
GENETICAL
CLASSIFICATION OF
JOINTS
By
A-Team
T.Venkatesh,
Ananth,
Varsha,
Kiruthika.

2. Joints may be defined as cracks or
fractures present in the body of a
rock.
These joints thus divide the rock into
parts or blocks.
The joints may be either open or
closed.
INTRODUCTION

4. Open joints – In which the rocks are
separated or opened out for some
small widths in a direction at a right
angle to the fracture surface.
Closed joints – However there is no
such separation.
CONTINUE…

5. Major Joints – In this prominent and
well developed and extending
continuously for considerable lengths
as compared to others.
Such major joints are called as master
joints or prominent joints.
CONTINUE…

6. The inclination of the joint plane with
the horizontal is called dip of the joint.
The line along which the joint plane
meets the surface is called strike of
the joint.
The strike direction is perpendicular to
dip direction.
ATTITUDE OF JOINTS

7. The Joints may be classified into two
major classifications.
1) Geometrical Classification
2) Genetic classification.
CLASSIFICATION OF JOINTS

8. The geometrical classification of joints
is based on attitude the of joints with
respect to that of the beds.
Accordingly there are three types of
joints that is strike joints, dip joints,
oblique joints & bedding joints.
1. GEOMETRICAL CLASSIFICATION

10. Strike joints are those in which the
strike of the joint is parallel to the
strike of the beds.
I . STRIKE JOINTS

11. Dip joints are those in which the strike
of the joints is perpendicular to the
strike of the beds .
ii. DIP JOINTS

12. Oblique joints are those in which the
strike of the joints are neither parallel
nor perpendicular to the strike of the
joints.
iii. OBLIQUE JOINTS

13. They are parallel to the bedding plane
having same plane having same strike
& dip.
iv-BEDDING PLANE

14. Depending upon the causes of their
origin, joints may be divided into
i. Tension joints
ii. Shear joints
iii. Compression joints
2. GENETIC CLASSIFICATION

17. Tension joints are those which are
formed due to tension forces or
stresses produce in the rock.
The direction of the joints is always
perpendicular to that of the force
which tries to pull them apart.
i. TENSION JOINTS

18. They are formed by the shearing
stresses , which tend to slide one part
of the rock against other.
They are developed during folding &
faulting.
These joints are developed in the
limbs of the folds.
ii . SHEAR JOINT

19. Rocks may be compressed to crushing
& numerous joints may result due to
compressive forces in this case.
In the core regions of folds where
compressive forces are dominant
results in the compression joint.
Iii . COMPRESSION JOINT

20. For civil projects the investigation of
rock joints is important because joints
acts as source of weakness for the
rocks, and also as a source of leakage
through the rocks.
The joints play a vital role in landslides
in hilly regions, because they serve as
a slip surface.
SIGNIFICANCE OF JOINTS

21. Physical and engineering geology –
S.K. Garg,
Engineering and general geology –
Parbin Singh.
REFERENCE:

22. THANK YOU