Envs 113 Environmental Engineer
Envs 113 Environmental Engineer
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Date Created: 02/04/14
Law of faunal assembages rock with similar fossils are most likely of a similar geologic age Environmental Geoogy geologic info to help us solve con ict in land use to minimize environmental degradation and to maximize the bene cial results V 39gtP t earth materials potential for use natural hazards land evaluation planning and environmental impact anaylsis hydrological processes geologic processes human population 1 The environmental problem ex Easter lsland 1 thing volcanic rock absorbed lots of the water sustainability 2 Population being controlled by educating women and men 3 Exponential growth current growth rate is 13 Growth rate measured as a percentage D70G to calculate growth NNoeAkt 4 Sustainabiltyevironmental solution Long term process development that allows for future generations to use similar resources sustainable growth impossible sustainbale resource use possible 0 resource extraction renewable sustainable human population possible sustainable ecosystems possible sustainable economy possible environmental crisis result of overpopulation urbanization and industrialization and not acting Continues global scale environmental problems climate change buming fossil fuels global warming deforestation soil erosion and waterair pollution mining development of groundwater and surfacewater resources systems and change 1 system part of the universeenvironment we chose to study 2 change is happening all the time speedrates of geologic processes inputouput analysis helps us identify changes steady state reduce stock or stock grows depending on input and output 0 average residence time time it takes total stock or supply of material to be cycled through a system TSF S size of the stock F avg rate of transfer through the system uniformitarianism quotthe present is key to the pastquot environmental unity one action causes others in a chain of actions Earth systems science study of the entire planet as a system in terms of its components Pleistocene era need to understand this for sustainability rel626 million years ago hazardous Earth processes 1 disasters becoming super disasters gt catastrophes Indonesian tsunami 200000 ppl killed population increased on the coast disasters come from poor land use practices 2 human population increase forces more people to live in hazardous areas 3 land use transformations increase runoff weaken slopes etc people living in New Orleans wetlands were drained levees built Hurricane Katrina disastrous bad land use 4 burning huge amounts of fossil fuels oil gas and coal increases the concentration of CO2 in the atm contributing to climate change science and values 1 address scienti c problems with hypotheses scienti c method theory is after hypothesis has been tested many times STRONG question eldlab work re ne question pose answer hypothesis test hypothesis conclusion if yesaccept If no new hypothesis 2 critical thinking with applied intellectual standards need clarity clarity assumptions accuracy precision relevance depth breadth logic signi cance timing calculations references conclusions faimess conclusions gather your own data come to your own conclusions so you can defend it 3 precautionary principle when a potentially serious environmental problem exists scienti c certainty is not required in order to take a precaustionary approach better safe than sorry Conclusion Why solving Environmental Problems is dif cult expediential growth often occurs lag times between stimulus and response may be long possibility of irreversible What is Engineering Geology applying geologic knowledge to engineering input to planning design construction stages of civil engineering Engineering Failures 1 St Francis dam 1928 o rocks may have dissolved along the schist rock landslides sedimentary rock dissolved when wet o geology cross section foliation planes metamorphic rocks schist fault separates foliation planes from sedimentary rock on East by st Francis dam had gypsum which is soluble 2 Baldwin hills Dam 1963 o importance of slow movement along faults o dam on edge of oil field subsided 1 m between 1923 and 1963 3 Teton dam 1976 o WET SPOT NOTICED CLOSE TO FOUNDATION OF EARTH FILL DAM 94M HIGH 960M LONG AT 9AM o FOUNDATION RHYOLIE WELDED TUFF compacted ash softweak rock HIGHLY FRACTURED 4 Katrina 2005 0 failure of inadquately sized levees on poor foundations 0 not given enough money Haiti 2010 6 Japan 2011 0 pumps needed to get water of tsunami outwalls kept water in pumps couldn39t work under wate LII Engineering Geology Rock Mechanics What are rocks aggregates of one or more minerals naturally occurring crystalline substances with defined properties What are minerals element or chemical compound that is normally crystalline and has formed as a result of geologic processes 1 Geologic Cycle 0 geologic conditions govem the type location and intensity of 2 Tectonic Cycle large scale processes that deform Earth39s crust and produce landforms 3 Rock cycle processes of rocks and minerals 3 general typesfamilies 1 igneous crystallization of magmamolten rock intrusive extrusive 2 sedimentary deposition and lithi cation of sediments 1 Detrital sedimentary 1 shale 2 sandstone 3 conglomerate 3 metamorphic changedmetamorphosed by heat pressure or chemically active uids 4 Biogeochemical cycles transfer of chemical elements through a series of reservoirs atm litho hydro biosphere 0 rate of transfer ux 1 carbon and phosphorus important chemicals being studied 2 building block of life global carbon cycle Environmental Implication with Minerals 1 quartz very abundant SiL2 strong Feldspar most abundant of earth39s crust 1 breaks down into clay red ag for engineering 2 FeS2 gt env problemcontact with water casues sulfuric acid Acid mine drainage try and neutralize it with calcium carbonate to bring up the pH 3 Basalt popular igneous rock has fractures contract in forms of polygons mostly hexagons strong 4 sandstones iron in there carbonate minerals calcite dissolves in water sinkholeslimestone LII Environmental Implication with Rocks 1 shale abundant finest textured of detrital rock clay and siltsized particles red ag 2 sandstones and conglomerate can be strong depending on cementing material 1 silicagtiron oxidegt calcium carbonategt clay 3 chemical sedimentary rocks 1 limestoneeasily weathers calcite dissolves Sinkholes Rock Mechanics Stress force per unit area that exists in a speci ed plane within rocks or other earth materialsF N force necessary to produce a1msecquot2 1Nmquot21Pa Strain measure of deformation of a material when load is applied stress Types of Stress compression 0 pushing together tensile o pulling apart shear 0 causes rotation Two forms of deformation under stress 1 elastic deforrnation deformed material returns to its original shape after the stress is removed 2 plastic deforrnation permanent strain doesn39t retum to original shape after stress is removed Rock Failure Rocks fail when they have been permanently deformed 0 plastic ow continuous process in which neighboring points remain neighboring but distances between points change ductile ow is transitional behavior between yielding by rupture and yielding by ow o rupture involves displacement of neighboring points along planes of slip Laboratory test uniaxial and triaxial o uniaxial just one push o triaxial confines more then just one stress WE CARE ABOUT THIS 0 Field Schmidt Hammergenerally break about 45 degrees angles cohesion The sticking together of particles of the same substance as water pressure increases the sheer strength decreases Engineering Properties of Rocks When can you test the lateral strength of a rock when a rock becomes wider from load still becomes shorter How can you find the lateral strength poisson39s ration gt lateral strain change of widthtotal width change in height total height Bulk specific Gravity speci c gravity of rockspeci c gravity of water 0 speci c gravity is unit weight G W0WWWS o W0 weight of rock specimen oven dried 24hrs o Ww saturated weight specimen after soaking for 48 hrs Bulk Density e mass of samplevolume of sample unit mass kgmquot3 or gcmquot3 Porosity percentage h vvoidvtotal X 100 Rip rap engineering term boulders along streams or dams to protect the sides Rock Durability hardness Mohs Scale abrasion resistance 0 AR wlW2Wl X 100 0 units percent wl original wt w2 wt after abrasion test 0 LA abrasion test steel drum Water Sorption weight of sorbed water to total specimen weight dry Rock toughness resistance to sudden impacts from 2 kg hammer dropped on rock sample record min fall to break rock measured as inches of fall per sq inch of surface area Rock soundness resistance of rock to freeze and thaw or wetting and drying rx altemately saturated units with Na2SO4 or MgSO4 and dried a speci c no of cycles The amount of spalling or disintegration by wt is measured is usually between 016 important for rip rap Soil or rock Engineer if can remove without blasting is a soil Geologist soil is a special material with speci c de nition based on processes Financial implications 0 how fast and cheap Shales compaction shales soil like cemented shale rock like shale sedimentary rock made of ne ne grains to engineers they are dangerous 0 most common sedimentary rock permeability measurement of how uid ows through may be termed differently now Conclusions The compressive strength increases as the lateral restraint increases due to lateral pressure that con ned rocks exert on one another Compressive strength of rock located at depth is greater than at ground surfacebut drops when rock is excavated and restraint is removed Therefore design of deep foundations based on uncon ned compression tests are on safe side Rock Discontinuities very important faults folds bedding planes 0 discontinuity between layers from change in processes joints 0 old erosion surface schistosity foliation 0 parallel allignment of in metamorphic rock Fractures are discontinuities no dates no rates Why are there examples where a mountain peak elevates despite erosion isostasy What is isostatic compensation every kilometer that is eroded 56th of a kilometer rises the land oats and 90 stays underneath Nonetheless the 10 that is oating above the surface of the mantle will be maintained although the erosion is consistent What is exfoliation when you erode the surface of a granite you allow for it to expand and fracture Glacial deposits and process there are glacial streams where the ice sheets actually can be moved They are not merely frozen to the bedrock Sand deposits and process if ground gets cold enough at first ice expands but sand can eventually contract from being so cold sand dunes migrate and therefore this can be a danger for roads or houses in the area deserti cation problems from climate change poor land use poor agricultural practices etcdepleting the land too much Applications in Rock Mechanics how do rock bolts increase the strength of the rock 0 compression strength bolt the rock into solid rocks tunnels o attempting to use it for capturing ground water 0 Geology and Tunnels 1973 Proctor Geological Engineer most important parameters in geologic report for a tunnel soundness of rock water in ows gas explosions natural gas joint spacing weathering fault zones generally want to cross it rather than go along it purposes transportation water systems soft ground such as plastic clay soft limestone shale oozing rock below water table Methods of tunneling soft rockmolesboring machines that grind soft rock shieldsteel cutters that rotate cut and cover Hard rockdrilling blasting remoVal by muckersdump truck often needs underground support such as rock bolts Planning using surface mapping suggests tunnel routes do not cross large faults pass through most competent rock possible avoid high groundwater areas where high volumes of water may enter tunnel May have zones of high uid pressure may need pumps and drains avoid areas with oil or gas avoid areas with squeezing rock such as bentonite or anhydrate compaction arti cial densi cation by humans what is important to know to identify the optimal strength from compaction water component Soil Consistency Limits What are the Atterberg Limits standard soil tests for fine fraction silts and clays Why are the Atterberg Limits critical bind the larger particles together strength can be very dependent on these particles that are holding everything together LL Liquid limit moisture content above which sample behaves as a liquid some water content above which soil will lose its sheer strength and ow more like a uid Pl Plastic limit moisture content above which sample behaves plastically plastically means it deforms collluviom is deposit that builds up at bottom of small slope desert pavement the gamish very fragile sedimentary rock that has been weathered down and carried by wind organic content in soils can be a red ag for engineers WHY bogs In eld can see grainsis coarse see with 10X lens is silt can t see with 10X lens this means that it is clay wellgrated engineer poorly sorted geologist a lot of different sizes more friction and cohesion with angular rocks clay has electrostatic forces and it therefore has more cohesion distinguished by size and the minerology What is Consolidationsettlement Deformation of a soila type of subsidencethat results from loading a soilas for example a buildinga dam or other structure ls due to expulsion of water and rearrangement of grains Rate of consolidation is a function of hydraulic conductivity of soil ls consolidation a hazard yes What is Compressibility Partly a function of elastic soil particles Excessive settlement will crack foundations and walls What does the amount of settlement depend on Magnitude of load Compressibility of soil layers especially clays and micaceous layers How does Coulomb s Law apply Works for soils and rocks Shear stress cohesion normal stress intemal friction Settlement Analysis Clay Normally loaded claypresent overburden pressure as great as ever existed Pre consolidated clayDuring its geologic history it was subjected to a pressure greater than at time of analysis Normally loaded clay settlement likely to be much greater than for pre consolidated clay Effective and Neutral Stresses in Soils Effective pressure is the pressure acting on grain to grain contact p bar pressure acting on the grains of the material Neutral pressure is uidwater pressure in connected pore spaces of a soil have to assume that the pore spaces are connected The effective pressure total pressure the water pressure As water pressure increases soil strength decreases and vice versa Land Use and Soil Land Transformation mostly anthropogenic Sediment Pollution ne grained sediments in water from run off mostly muddy What are the three main goals of Ecological Restoration an action to restore more natural processes physical hydrological ecologic enhance recovery of native species restore habitat What are the most common ecosystems restored river oodplain wetland beach habitat for endangered species What are the BIG THREE OF RESTORATION hydrologic processes ground water surface water interaction with geology and vegetation response soilsgeology vegetations why do invasive species grow so much they dont have natural controls such as predators Conclusions There is a signi cant difference between the distribution of Arundo and Willow roots Arundo donax likely contributes more to bank strength when bank height is small 0ltbhlt20cm than Red Willow As bank height increases Arundo provides little or no cohesion at lower depths in the bank compared to Red Willow and may lead to greater destabilization of the bank through undercutting and subsequent cantilever failure Final Study sheet Chapter 3 Soils Plastic index PNumerica difference between liquid limit LL and plastic limit PL Chapter 7 Slope Processes 2 types of slopes Hard strong granite Free face cliff and talus slope Rock fall deposits Relatively weak rock top soil convex slope straight slope concave slope Translational sliding downslope movement of unconsolidated materials in which particles move about and mix within the mass Bedding planes Fractures Unconformities Faults Schistose foliation planes Creep Very slow flowage of earth flow or mudflow Debris flow is less than 50 fines sand silt clay vs mudflow more than 50 fines Lateral Spread occurs on a gentle slope start with liquefaction of silts clays Slope stability has a safety factor if greater than 1 than resisting forces are greater than driving forces 125 is a strong starting point These forces are not static and change often times The forces include Type of earth materials Slope angle and topography Climate Vegetation VVater Time Rotational slides or clumps occur on weak rock On a slope much less than 90 the direction of principle stress changes continuouslynot constant Therefore failure surface can39t be planarmust be curved Translational slides are planar occur along inclined slip planes within a slope W product area above slip plane Aunit weight of slope material and the unit thickness Subsidence events occur when water coal or salt are removed below the sinking site Preventing Landslides 1Drainage control divert surface runoff slope cut walls drains 2Grading Cut and fill operation used to take weight from top of slope and fill bottom reduces gradient Cutting benches on steep slopes 3Sope supports Retaining walls constructed from concrete anchored below the slope drainage holes for water Vegetation Provides cushion cover from impact of water facilitates infiltration of water Root system creates apparent cohesion Ads weight to slope good and bad ice plants VVater Spontaneous liquefaction of clay sediment can occur Anchorage Alaska 1964 Chemical weathering over time Carbonic acid H2CO3 decomposes limestone Slow creep destroyed Vaiont Dam Earthquakes Moment Magnitude Based on seismic moment area of rupture amount of slip and rigidity of rocks Loss of energy is called attenuation All plate boundaries are called faults Focus point at which rocks rupture to produce quake Epicenter location on the surface above the Focus Seismograph records displacements Magnitude 7 is 10x larger displacement on seismograph than magnitude 6 with 32X more energy Shakemap shows extent of potential damage from shaking California sits at the convergence of two lithospheric plates that move past each other Slip rate is the rate of longterm movement recorded in millimeters per year mmyr Active faults are considered to have moved in the last 10000 years the Holocene epoch Normal FaultStress is tensile pulling apart slide up and down Syncline formed valley Reverse faut Stress is compression pushing together up and down top is Anticline mountains RightLateral strikesslip fault Average rate of recurrence interval of earthquakes on a particular fault is determined by three following methods 1 Paleoseismic dataAveraging the time intervals between earthquakes recorded in geologic records 2Sip rate average displacement per event 1m divided by slip rate 2mm per year average recurrence is 500 years 3 Seismicity Using historical earthquakes and averaging the time intervals between events Methods of Estimating Fault Activity Seeing offset streams Study of soilsdissimilar ages for soils on opposite sides of faults Types of Waves Body Waves P waves compressional waves faster detectable to human ear in atmosphere travel slowly through liquids Fastest through consolidated bedrock S waves shear waves travel only through solid material Approximately 2 of speed of P waves Updown and side to side motion Surface waves R waves complex horizontal and vertical ground movement that may destroy building wave propagation and rolling move in different directions Mud amplifies shaking High frequency shaking vibrates low buiding low frequency shaking vibrates tall buildings Humans increase earthquakes loading the earth with dams or structures Deep explosions Disposing of trash into the ground Supershear Propagation of rupture is faster than the velocity of shear waves Can produce shock waves that produce strong ground motion along fault May increase damage from a large earthquake Reducing earthquake hazards recognition of active faults determine earth materials that are sensitive to shaking develop new ways to predict control and adjust to earthquakes Predicting shortterm not really possible Radon gas emissionseismic gaps animal behavior deformation of ground surface Elastic strain is deformation that is not permanent dropped after an earthquake Denver Coloradohuman caused earthquake Recurrence Interval RI ratio of slip per event to slip rate Slip per event is often assumed Slip rate can be determined from field data Geologists need to evaluate Peak Ground acceleration PGA Spectral acceleration S at a period of 03 seconds for small building S 1arger buildings Volcanoes Rock type Rhyolite potassium and sodium rich feldspar quarts Domes are less explosive Andesitic volcanic rocks are produced at subduction zones rising magma mixes with both oceanic and continental crust Caldera eruptions are rare but extremely violent 3 major groups of lava 1Basaltic most abundant andesitic rhyoh c PyriteWeathers to contribute to acid mine drainage CalciteAssociated with the rock limestone QuartzA hard mineral commonly found in granite ClayVery weak mineral associated with landslide along a fracture Dry sand is cohesion less Bouders highest hydraulic conductivity SchistHas planes of weakness due to alignment of mineral grains SchistRock that failed by landslide at St Francis Dam Compaction shae weakest rock with high slaking potential 10 LimestoneDissolves in weak soil acids 9 39 Squot3939gtS quot 11 BasaltMay have columnar joints and flow tubes 12 BasaltRock associated with Teton Dam failure 13 Gravel and sand has highest permeability 14 Coarse materials gravel and sand have low compressibility 15 Clay and natural cements have low erosion factors 16 Montmorillonite can swell to 15x its potential 17 Bentonite comes from volcanoes tuff and swell a lot 18 Silicates most abundant chemical composition in earth39s crust 19 Shae most common sedimentary rock made of clay or silt 20 Sandstones strong for engineering purposes silica strongest 21 Skate metamorphic rockexcellent foundation 22 Gneisshard and tough 23 Marble like limestonenon foliated metamorphic rock 24 Shaleprone to landslides loose sediment sumps occur 25 Graniteprone to sliding along fractures Increase volume of 3 is considered potentially hazardous Angularity of particles increases stability Rock strength depends on hardness stiffness and discontinuities Adaptive management application of science to restoration involves scientific endpoints and goals includes monitoring feedback and potential change Optimum moisture content water content at zero air voids moisture content at maximum dry density compaction Lands des Slope processes Fluvialweatheringgroundwatermasswasting landsliding Colluvium soil Relatively permeable Bedrock low permeability Important Variables Earth materialsTopographyWatervegetationclimatetime Cantilever fracture rock below is weathered so top falls out Stream banks and steep bluffs Waves Size determined by Wind Velocity duration fetch VLT Plunging breaker happens with steep beach Spilling breaker created by gentle slope beach Minimize coastal erosion Seawalls levees jetties groin concrete engineering Land use beach nourishment Volcanoes Volcanic domes Rhyolite rock explosive Volcanic Shieds Basaltic rock fow mid ocean ridges Composite vocanoes subduction zones andesitic rock Calculation Explanations Specific Gravity Relative Density Ratio of density of the material to the density of water SGppwater Pdensity of fluid or substance kgm3 Pwater density of water often times 1000kgm3 If you have density you can divide it by specific weight of water Unit weight Specific weight weight per unit volume Weight is a force Y08 yspecific weight p density kgm3 g acceeration of gravity ms2 981 ms2 ex Specific weight for water is 624 bft3 981kNm3 in imperial units Specific weight can be calculated like Y 1000 kgm3 981 ms2 981O Nm3 981 kNm3 Calculating Young39s modulus to11silc sti1 ess 7 FA0 FLO C 4AL te11sile sti1 ai11 where E is the Young39s modulus modulus of elasticity F is the force exerted on an object under tension A0 is the original cross sectional area through which the force is applied Area of the face touching other surface AL is the amount by which the length of the object changes L0 is the original length of the object If you have a graph showing Extension against Force applied Stress forcecross sectional area Strain extensionoriginal length ForceExtension 1gradient of curve So Young39s Modulus Original lengthgradientcross sectional area Draw Mohr s envelope Average compressive strength length of the small first circle Unconfined means you start at zero Confining pressure is the starting point on the x axis axial stress to break sample is the end point on the x axis x axis Norma strength X 10quot7 y axis Sharing resistance strength Shear strength equation Example 14x10quot6 omega tan 45 14 is found where the line hits the y access y intercept 45 is found by the tangent to the 3 circles Water Pressure Effective pressure total pressure Neutral water pressure height under water table 624 pcf Neutral pressure is fluid water pressure in the connected pore spaces in the soil Compute vertical intergranular pressure at 30ft Lecture 5 Internal Processes Come from plate tectonics Result of internal energy of Earth External processes come from forces on Earth39s surface Atmospheric effect Energy from the Sun Disaster limited time in defined area 10 or more people killed 100 or more affected State of emergency declared International assistance required Catastrophe Massive disaster that requires significant amount of money or time to recover Natural Hazards Vary in ability to cause catastrophe May have more impact on human life OR property Increase in Natural Disasters because increase in human population environmental damage to land and poor land use climate change Benefits of Natural Hazards Foods build floodplains and deltas Earthquakes build mountains Volcanoesmake new land Landslidesmake lakes Understanding Natural Processes as Hazards Hazards are predictable from scientific evaluation Risk analysis is an important part of understanding these effects Links exist between hazards and the physical environment disasters are now catastrophes due to list above consequences of hazards can be minimized Best solution preparation and knowledge identify location most hazardous areas mapped Determine probability of event based on past events and current conditions Observe precursor events events that lead up to a hazardous event Forecast gives probability of event most events Prediction gives specific arrival time date magnitudesome events Other solutions Engineering Insurance Bear losses Be proactive Risk probability of event x consequences Acceptable risk amount of risk that individual or society are willing to take Population has tripled in 70 years exponentially more hazards less food less water more waste Impact of hazard depends on MagnitudeAmount of energy released Frequencyinterval btw occurrences land use increases this climategeoogyvegetation population land use Impact of a process is a function of magnitude and frequency inverse relation between these two Uniformitarianism present is key to the past Prediction based on historical occurrences Environmental Unity One action causes other in a chain of actions and events Scientific method formulate a questionhypothesisdata
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