Engineering Geology Introduction PDF

Engineering Geology Prof. Mohamed Arnous Geology Department Faculty of Science, Suez Canal University  What you need to do well !!!! 1. Attend to all classes as possible. 2. READ the textbook and the lab manual. (Preferably before coming to class) 3. Carry out the required as...

Engineering Geology Prof. Mohamed Arnous Geology Department Faculty of Science, Suez Canal University  What you need to do well !!!! 1. Attend to all classes as possible. 2. READ the textbook and the lab manual. (Preferably before coming to class) 3. Carry out the required assignments. 4. Then, study hard for the exams.  We Live in Two Worlds Natural World Constructed World Self-Regulating Managed.. These Are Increasingly In Conflict What are the Earth Sciences? ‫الجيولوجيا‬  Geology literally means "study of the Earth.“ Physical geology examines the materials and processes of the Earth. Historical geology examines the origin and evolution of our planet through time. Engineering geology is the application of geological data, techniques and principles to the study of rock and soil surfacing materials, and groundwater.  What is Engineering Geology ❑Engineering geology is the application of geological data, techniques and principles to study rocks, soil surficial materials, and groundwater. ❑This is essential for the proper location, planning, design, construction, operation and maintenance of engineering structures. ❑Engineering geology complements environmental geology Importance of engg geology in Civil Engineering practice What is Engineering Geology? Engineering geology is the application of geological data, techniques and principles to the study of rock and soil surficial materials and ground water. This is essential for the proper location, planning, design, construction, operation and maintenance of engineering structure. 12 Importance of engg geology in Civil Engineering practice What does Engineering Geology study? Rock, soil, water and the interaction among these constituents, as well as with engineering materials and structures. 13 Importance of engg geology in Civil Engineering practice Why Engineering geology? Serve civil engineering to provide information in 3 most important areas: Resources for construction; aggregates, fills and borrows. Finding stable foundations; Mitigation of geological hazards; Identify proplems, evaluate the costs, provide information to mitigate the problem 14 Earthquakes & Tsunamis Indian Ocean Tsunami December 26, 2004 186,983 dead 42,883 missing What are the Earth Sciences? Rocks... of course Source: William E. Ferguson Mountains Streams and rivers Ancient life (fossils) Source: Breck P. Kent Volcanoes Earthquakes Land slides Groundwater Oil and gas Mining: Coal Mining: Metals  Formation of Earth About 3.8 b.y. ago, the Earth stabilized and a semi-permanent crust formed. What are the Earth Sciences?  Interior of earth ◼ Crust: ◼ Continental crust (25-40 km) ◼ Oceanic crust (~6 km) ◼ Mantle ◼ Upper mantle (650 km) ◼ Lower mantle (2235 km) ◼ Core ◼ Outer core: liquid (2270 km) ◼ Inner core: solid (1216 km)  Values in brackets represent the approximate thickness of each layer  Earth’s layers Earth initially formed a metalic core surrounded by a magnesium-silicate mantle As it cooled, the inner part of the core became solid Lighter elements continually move from the mantle to the surface.  Earth’s layers Core made of iron-nickel alloy including: Solid inner core Liquid outer core Mantle made of magnesium- silicates including: The inner mantle The asthenosphere — weak, partially molten layer Relative thickness of layers  Earth’s layers The lithosphere The rigid upper-most layer of the mantle The crust — a thin rind of light elements floating on top of the earth. Also what you’re sitting on.  Layers of the Earth The earth is divided into three main layers: Inner core, outer core, mantle and crust. The core is composed mostly of iron (Fe) and is so hot that the outer core is molten, with about 10% sulphur (S). The inner core is under such extreme pressure that it remains solid. Most of the Earth's mass is in the mantle, which is composed of iron (Fe), magnesium (Mg), aluminum (Al), silicon (Si), and oxygen (O) silicate compounds. At over 1000 degrees C, the mantle is solid but can deform slowly in a plastic manner.  THE CRUST The crust is much thinner than any of the other layers, and is composed of the least dense calcium (Ca) and sodium (Na) aluminum- silicate minerals. Being relatively cold, the crust is rocky and brittle, so it can fracture in earthquakes. The shell of the earth, the crust, can be said to have two different thicknesses. Under the oceans, it is relatively thin. It varies in thickness from 5 to 8 km. Under the land masses, it is relatively thick. The thickness of the continental crust varies from 10 to 65 km.  THE CRUST The eggshell analogy for the crust is not an exaggeration. It is paper thin compared with the earth’s radius, which is approximately 6400 km. The total weight of the continental crust is less than 0.3% of the weight of the earth. Variations in the crust thickness are compensated by the weight of the water and the differences in the specific gravities of the crust under the oceans (3.0 to 3.1) and under the continents(2.7 to 2.8).  THE CRUST If one thinks of the crust as virtually floating on the mantle, one is less likely to wonder why the earth does not wobble as it rotates about its axis. The weight of the crust plus the mantle has a reasonably uniform distribution over the globe.  THE MOHO The Moho, or the Mohorovicic Discontinuity, refers to a zone or a thin shell below the crust of the earth that varies in thickness from 1 to 3 km.  THE MOHO In seismology, the term "discontinuity" is used in its general sense. It refers to a change over a short distance of a material property. In this case, the "short distance" may be as long as 3 km, a trifle compared with the radius of the earth. In that zone, the P-wave velocity has been observed to increase from approximately 6 to approximately 8 km/sec. The Moho is considered to be the boundary between the crust and the mantle. The increase in P-wave velocity is ascribed to change in composition of the medium. Rocks of the mantle are poorer in silicon but richer in iron and magnesium  THE MANTLE The mantle can be thought of having three different layers. The separation is made because of different deformational properties in the mantle inferred from seismic wave measurements. (1) The upper layer is stiff. It is presumed that if the entire mantle had been as stiff, the outer shell of the earth would stay put. This stiff layer of the mantle and the overlying crust are referred to as the lithosphere. The lithosphere is approximately 80-km thick  THE MANTLE (2) Beneath the lithosphere is a soft layer of mantle called the asthenosphere. Its thickness is inferred to be several times that of the lithosphere. One may think of this as a film of lubricant although film is not exactly the word for something so thick. It is assumed that the lithosphere, protruding (meaning: extending beyond) parts and all, can glide over the asthenosphere with little distortion of the lithosphere  THE MANTLE (3) The mesosphere is the lowest layer of the mantle. Considering the vagueness in defining the lower boundary of the asthenosphere it would be expected that the thickness and material properties of the mesosphere are not well known. It is expected to have a stiffness somewhere between those of the lithosphere and the asthenosphere.  THE CORE At a depth of approximately 2900 km, there is a large reduction (on the order of 40%) in the measured velocity of seismic waves. The boundary between the mantle and the core is assumed to be at this depth. Because no S-wave has been observed to travel through the material below this boundary for a thickness of approximately 2300 km, it has been inferred that the core comprises two layers. The 2300-km thick outer layer which is in a molten state and an 1100-km thick inner layer which is solid.  THE CORE It is known that the pressure increases toward the center of the earth. So does the temperature. The liquid outer layer versus the solid inner layer is rationalized by recognizing that the melting point of the material increases (with pressure) at a faster rate than the temperature as the center of the earth is approached.  We Live in Two Worlds Natural World Constructed World Self-Regulating Managed.. These Are Increasingly In Conflict Thanks a lot For Attention