joints and its classification and its recognition

joints and its classification and its recognition

1. A SEMINAR ON JOINTS AND ITS CLASSIFICATION& RECOGNITION OF JOINTS DEPARTMENT OF APPLIED GEOLOGY DR.HARISINGH GOUR VISWAVIDYALAYA,SAGAR [M.P.] SUBMITTED TO –PROF.A.K. SHANDILYA SUBMITTED BY –SHIVAM JAIN

2. Joints Joints are the planar structure and simply known as crack along bed/rock without displacement. Joints/Fracture is a planar or sub planar discontinuity which causes movement ,and loss of cohesion and change in mechanical properties of rock and minerals. Joints- A fracture without measurable shear displacement (cracks or tensile fractures) Fault : A fracture with measurable displacement.

3. PARAMETER OF JOINTS Strike direction of joints Amount of dip of joints Dip direction of joints

4. Classification of Joints

5. Joint arrays Systematic vs nonsystematic joints Systematic joints: Planar joints Joints are parallel or subparallel . Same average spacing Nonsystematic joints: Irregular spatial distribution Not parallel to one another. Different average spacing

6. Based on its Geometry The geometrical classification of joints .is based on attitude the joint with respect to that of the beds Accordingly there are three type of joints that is strike joint ,dip joint ,oblique joint & bedding joints There are three type of joint which are:- STRIKE JOINTS - are those in which the strike of joint is parallel to the strike of beds DIP JOINTS -dip joints are those in which the strike of joint is perpendicular to the strike of beds. OBLIQUE /INCLINED JOIINTS -oblique joins are those in which the strike of joint are neither parallel nor perpendicular to the strike of the joints. BEDDING JOINTS -they are parallel to the bedding plane having same plane having same strike & dip.

7. CLASSIFICATION OF JOINT Based on the dip of joints :- Horizontal joints-0°-5° Sub horizontal joints-5°-10° Low angle joints-10°-30° Moderate angle joint-30°-60° High angle joint-60°-80° Sub vertical joint-80°-85° Vertical joint—85°-90°

8. BASED ON ITS GENESIS There are three types of joints on the basis of genesis – TENSION JOINTS Tension joints are those in which are formed due to tension forces or stress produce in the rock. SHEAR JOINTS They are formed by the shearing strsses , which tends to slide one part of rock against other. COMPRESSION JOINTS Rock may be compressed to crushing &numerous joint may result duto compressive forces in this cases.

9. Process of formation of joints 4.Torsion forces 3.Shear forces 1.Compression forces- 2.Tensile forces

10. Formation of Joints 1.Joints are brittle fractures which develop either by tensile failure or by shear failure. 2.When this happens, the rock fractures in a plane parallel to the maximum principal stress and perpendicular to the minimum principal stress (the direction in which the rock is being stretched). 3.A large number of joints form after the close of the tectonic cycle and during a slow uplift of the rocks.

11. Formation of joints by extension and contraction

12. Geometrical relation with fold • The different geometric relation some times expressed in terms of three mutually perpendicular tectonic axes a,b and c ( sandar 1930) with the b axis parallel to the fold axis and c-axis normal to the bedding. • Orientation of b-axis remains constant, but the orientation of c and a-axis change in different parts of fold .

13. • Joints develop normal to the fold axis called ac-joint or cross-joints( fig.a ) • Joints develop parallel to the axial plane of fold called bc -joints or longitudinal joints( fig.b ). • h0l- joints are conjugate joints intersecting along the fold axis(b-axis) and are symmetrically oriented with respect to the axial plane. Symbol 0 indicate that these are parallel to the b-axis at the hinge .( fig.c ) • hk0-joints are conjugate joints intersecting along a line which is perpendicular fold axis and lies parallel to the axial plane ( fig.d ) • hk0-joints indicates that these are parallel to the c-axis at the hinge and 0kl-joints indicates that these are parallel to the a-axis at the hinge z one.

14. Geometrical relation with fault • Joints of different types may develop during faulting among these the feather or pinnate joint are important. • The angle between fault plane and joint is 45˚ which is help to sense the movement of the fault block.

15. Surface morphology of joints • Joints surface sometimes characteristic surface marking. In generally two type; Hackle marks and rib marks. • Hackle marks are faint ridge on the joint surface. Plume structure common type of hackle mark, feather-like marking on the joint surface with a central axis from which the rays or barbs branch out either side. • Normally found in shear fracture zone rare in extensional fracture zone

16. Cross-sectional sketch illustrating a multilayer that is composed of rocks with different values of Young’s modulus. The stiffer layers (dolomite) develop more closely spaced joints Young’s modulus, E: stress related to strain (elasticity): s= E.e Large E, large s, more fractures Small E, small s, fewer fractures

17. Sheeting (Exfoliation) • Sheeting is a tensional due to release of loading during erosion. • The release of the compressional force on rock that have been under high confining pressure sometimes cause ruptures perpendicular to axis of compression.

18. Columnar joints • Basalt solidifies at about 1,000˚C and during subsequent cooling it contracts of lave flow. • The resulting tensional forces act primarily in the horizontal plane and equal in all direction within this plane. • When rupture eventually take place, three vertical fracture, making angles of 120˚ with each other, radiate out from numerous centers.

19. Mural joints In granitic rock masses. Three sets of joints may occur. In such a way one is horizontal and other two are vertical. All three sets being mutually right angle to each other . This type of joints dividing the rock masses into cubical blocks or murals is called mural joints .

20. MASTER JOINTS Meters of long joints having splay joint are known as master joints These joints may open ,closed or may be filled with secondary mineral Behavior of these joints depend upon mineralogy ;if rock is fined grained , joint surface morphology will be smooth and if rock is coarse grained , joint surface morphology will be rough. These joints help us to develop secondary porosity and help in oil accumulation.

21. SECONDARY MINERAL DEPOSITION OF CALCITIC SOLUTION

22. PRINCIPLE OF FALURE OF RUPTURE/GENESIS OF JOINTS FACTOR CONTROLLING THE RUPTURE – 1.The nature of deformation preceding rupture 2.Physical condition at the time of rupture . 3.stress is necessary to cause rupture . 4.The orientation of fracture relative causative structure stress

23. RECOGNITION OF JOINTS 1 . Flat or smooth surface, joint surface are develop 2.Gap between joints. 3.block has been displaced due to faulting the joint may be observed in the field but it is necessary data in order to convey other end to make pertinent analysis .

24. FIELD STUDYOF JOINTS:- 1.The joint may be observed in the field ,but it is necessary to gather significant statistical data in order to convey the fact to other and to make pertinent analysis. 2.In the engineering project such as dam ,dam sites canal, tunnel , roadways,railways,tracks,etc . It is usually possible to make large scale map such as 1:100 or 1:200 in cm after unconsolidated and bedrock exposed them joints fault,fold,can be seen . 3.In most geological map are smaller scale 1:2000ft ,1:5000,1:1km or 1;5km scale it is thus necessary generalize the data obtained at individual outcrop.

25. Importance of joints • Mineral exploration in mining industries. • Granite industries for quarrying rock blocks. • To find the ground water flow in Hydrogeological aspect. Good permeable layer for aquifer, act oil and gas reservior , it helps in secondary migration of hydrocarbon e.g. groundwater and pollutant within aquifer petroleum in reservoir and hydrothermal circulation at depth , within bedrock. • Bed rock analysis for Construction of tall building in hill area. In hilly region joints get easily lubricated due to moisture and start sliding causes landslides. To understand the geology and geomorphology of local area Control weathering and erosion. Joints are important to the economic and safe development of petroleum , hydrothermal and groundwater resources and the subject of intensive research relative to development of these resources.

26. T hankyou