brief INTRODUCTION TO ROCK MECHANICS.pptx

introduction about rock mechanics and topics related like slope stability, rock failure, and many more. also includes computation among slopes

1. INTRODUCTION TO ROCK MECHANICS Reporters: Anongos, Rhienstal Quizzagan, Edmar

2. What is a rock? To  geologists , a rock is a natural substance composed of solid crystals of different minerals that have been fused together into a solid lump. The minerals may or may not have been formed at the same time. What matters is that natural processes glued them all together. Types of Rocks igneous rocks  are volcanic and form from molten material. Sedimentary rocks  are formed from eroded fragments of other rocks or even from the remains of plants or animals.  Metamorphic rocks  are sedimentary or igneous rocks that have been transformed by pressure, heat, or the intrusion of fluids. 

3. What is rock mechanics? Rock mechanics is the study of the mechanical behavior of subsurface sedimentary strata and rocks that are formed. The basic principle is that rock simply responds to stress by changing in volume or form. The change in the rock volume or form due to the applied stress is called strain. Rock mechanics determines how a particular rock reacts when it is put to the use required by mankind for buildings, roads, bridges, dams, tunnels, and other civil engineering uses. It will assess the bearing capacity of the rock on the surface and how the force applied on the rock by the structures being built on it will affect the rock at various depths.

4. Rock mechanics It is convenient to subdivide rock mechanics into the following branches: a) Structural rock mechanics , which is concerned with the stability of engineering structures in which the material is predominantly rock. b) Comminution , which is concerned with the reduction of rock to small fragments by the application of external forces as in drilling, blasting, cutting and grinding.

5. What is the purpose of rock mechanics? The purpose of rock mechanics is to understand how and why rock deforms either as a sporadic or catastrophic event. It is commonly applied to: civil and geological engineering, mining, drilling, and conventional reservoir geohazard evaluation.

6. What are the characteristics of rock mechanics? Rock mechanical properties mainly include elastic modulus, Poisson’s ratio, and rock strength. These parameters can be obtained by lab experiments of core samples or by in-situ tests. The other characteristics of rocks include time-dependent rheological and creep behaviors (Wang 1981).

7. 5 main characteristics of rock color , streak, cleavage, luster , Hardness These characteristics are used to help identify a rock.

8. streak, ( the colour of a mineral in its powdered form . It is usually obtained by rubbing the mineral on a hard, white surface, such as a tile of unglazed porcelain, so as to yield a line, or streak, of fine powder.) cleavage, ( is  a type of rock layering or planar formation that forms within finely grained rocks due to deformation and metamorphism caused by heat and pressure .) luster , ( describes how a mineral's surface reflects light and how the interior of the mineral may refract or bend light .)

9. Hardness

10. What is stress in rock mechanics? Stress is the force exerted per unit area and strain is the physical change that results in response to that force. When the applied stress is greater than the internal strength of rock, strain results in the form of deformation of the rock caused by the stress. Strain in rocks can be represented as a change in rock volume and/or rock shape, as well as fracturing the rock. There are three types of stress: tensional, compressional, and shear.

11. T ypes of stress: Tensional stress involves forces pulling in opposite directions, which results in strain that stretches and thins rock. Compressional stress involves forces pushing together, and the compressional strain shows up as rock folding and thickening. Shear stress involves transverse forces; the strain shows up as opposing blocks or regions of the material moving past each other.

12. How does rock mechanics connected to Civil Engineering? Understanding the behaviour of rocks is important in construction because it allows engineers and contractors to design and build structures that are appropriate for the specific rock conditions at a given site, be it for civil or mining purposes.

13. What is the use of rock mechanics in civil engineering? Rock mechanics can help to predict how rocks will respond to drilling, blasting and tunnel and shaft boring, and can be used to design safe and effective support systems for deep excavations, open cuts, tunnels and ventilation shafts.

14. Understanding the importance of rock mechanics Why would I need a rock mechanics engineer for my project? A rock mechanics engineer is a specialised type of engineer who has expertise in the mechanical behaviour of rocks and the design of structures built on or in rock. If your project involves construction on or in rock, a rock engineer can help to ensure that the project is designed and built in a safe and effective manner. For example, a rock engineer can help to evaluate the geologic conditions at the project site, identify potential risks and hazards, and recommend appropriate design and construction techniques to mitigate those risks. They can also provide expert advice on the use of specialised equipment and techniques for drilling, blasting, ripping, rock hammering, cutting and other rock-related operations. In general, a rock engineer can help to ensure that your project is completed successfully and safely, and that it is built to withstand the forces that will act on it over time.

15. Understanding the importance of rock mechanics Key industries Rock mechanics is particularly important in mining and tunnelling. In the mining industry, it is used to understand the behaviour of rocks in the subsurface, and to design safe and efficient methods for excavating and extracting minerals. For example, rock mechanics can help to predict how rocks will respond to drilling, blasting and tunnel and shaft boring, and can be used to design safe and effective support systems for deep excavations, open cuts, tunnels and ventilation shafts.

16. Rock mechanics is particularly important in mining and tunnelling. In tunnelling, rock mechanics is also critical for the design and construction of tunnels and shafts. It is used to evaluate the geologic conditions along the tunnel or shaft alignment, and to determine the appropriate excavation method, such as drilling and blasting, tunnel boring with tunnel boring machines (TBM), road headers, blind boring or raise boring and support system for the specific rock conditions. For example, rock mechanics can help to predict the stability of the rock surrounding the tunnel and can be used to design support systems that will prevent the tunnel from collapsing or deforming.

17. Understanding the importance of rock mechanics What is rock mass classification? Rock mass classification is a system that organises rock into classes based on their characteristics. It provides a consistent and standardised method for characterising the physical and mechanical properties of rocks. This is important because the strength and deformation behaviour of rocks can vary widely, depending on factors such as their composition, structure, and the geologic conditions under which they formed. By classifying rock masses using a standardised system, engineers and geologists can better predict the behaviour of rocks and design structures that are appropriate for the specific rock conditions at a given site.

18. Understanding the importance of rock mechanics How to assess rock characteristics? There are several ways that engineers can test the characteristics of rocks. Common methods include: Compression testing, Tension testing, and Indirect testing.

19. Compression testing: This involves applying a compressive force to a rock sample and measuring how much it deforms or fractures under the applied force. This can provide information about the rock’s strength and stiffness. Tension testing: This involves applying a tensile force to a rock sample and measuring how much it stretches or fractures under the applied force. This can provide information about the rock’s ductility and toughness. Indirect testing: In some cases, engineers may not have access to a rock sample, or the sample may be too large to test directly. In these cases, they can use indirect methods to estimate the rock’s characteristics. For example, they may use borehole logs or geophysical surveys to infer the rock’s composition and structure, or they may use statistical methods to analyse the results of past rock-related projects to predict the behaviour of the rock at a given site. Overall, the specific methods used to test rock characteristics will depend on the type of rock being tested, the available data, and the specific engineering objectives of the project.

20. APPLICATIONS OF ROCKMCHANICS SURFACE STRUCTURES: Low rise(Housing) High Rise(Towers) High Load(Hydro dams, Power Plants, Bridges) TRANSPROTATION ROUTES Highways Railways Sewage Lines Pipelines EXCAVATIONS Quarries Open pits Strip mines Trenches Etc.

21. MECHANICAL CLASSIFICATIONS OF ROCKS: