Popular in Geotechnical Engineering
Popular in Engineering and Tech
This 27 page Bundle was uploaded by dana Notetaker on Tuesday February 16, 2016. The Bundle belongs to CAE 370 at University of Miami taught by Alejandro Montenegro in Spring 2016. Since its upload, it has received 49 views. For similar materials see Geotechnical Engineering in Engineering and Tech at University of Miami.
Reviews for CAE 370
I love that I can count on (dana for top notch notes! Especially around test time...
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 02/16/16
Chapter 1 Who is? 1. Wolmar Fellenius? He’s the port engineer in Sweden, a professor at the royal institute of technology in stockhom and the chairman of geotechnical commission of the Swedish state railways. He conducted the first large scale geotechnical studies and developed exploration, sampling, testing and analysis techniques. 2. Karl Terzaghi? Also known as the father of soil mechanics. In 1916, he began his research on the behavior of soils, including the studies of piping failures in sand beneath sand and settlement clays 3. Ralph Peck? He developed the observational method and applied this approach to solving engineering problems. With the knowledge gained by terzaghi, he studied the areas of strength in soft clays, earth pressure and tunnel lighting. What are the branches of Civil engineering? 1. Structure 2. Waste water 3. Environmental 4. Geotechnical Geotechnical engineering deals with/ what are the issues addressed by geotechnical engineers? 1. Soil and rock condition 2. Ground water condition 3. Extraction, grading or filling condition 4. Earth slopes 5. Retaining walls 6. Earthquake 7. Tunneling 8. Deep and shallow foundations Geotechnical engineering design process is? / What are the field explorations? 1. Drilling Vertical holes (aka exploratory borings) 2. Shallow excavations 3. Hand samling Geotechnical services during Construction include? 1. Examining soil and rock conditions 2. Measuring the movements and ground water leve (aka observation method) 3. Providing quality control testing Modern geotechnical engineering is? 1. Engineering judgments 2. Interactions with other engineers 3. Revising the design recommendation What are the analyses of geotechnical engineering? 1. The ability to know the behavior of rock and soil 2. Digital computers have actually made more construction failures 3. It is best to perform geotechnical analysis with 2 or 3 sigfig. How do we determine the geotech. Material properties? 1. Performing a field reconnaissance by examining the soil and rock 2. Drilling exploratory borings to obtain rock and soil sample 3. Testing samples in mechanics laboratory 4. Measuring ground water levels and pressure, soil measurements and other similar attributes What is the unconfined Comparison test? 1. Moisture content 2. Sieve analysis 3. CBR 4. Proctors 5. Visual Classification Geotechnical construction include: 1. Drilling a hole in the ground and filling it with reinforced concrete to for a drill shaft foundation 2. Deep excavations extends to 10m(30ft) below ground water Chapter 2 2.2 Rocks 1.What are the three major rock types? Igneous Rocks Sedimentary Rocks -Clastic rocks -Carbonates metamorphic Igneous Rocks: Begins with magma, a molten rock deep inside the earth. This magma cools as it moves upward towards the surface of the ground, forming igneous rocks 1.What are the types of igneous rocks? Intrusives (plutonic rocks): form below the ground surface from the relatively slow cooling of magma. They include large body of rocks known as plutons and smaller sheet like rock known as sills and dikes. Such as: -Granite -Gabbro (equivalent to basalt) -Diorite Extrusives (volcanic rocks): results from the relatively rapid cooling of molten lava at ground surface. They are generally fine-grained and have smoother surfaces. Examples: volcanic ah, bypass the rocks shape. Such as: -Basalt (very hard) -Andesite -Rhyolite (Equivalent to granite) Note: Un-weathered igneous rocks have excellent engineering properties. Weathered igneous rocks are less desirable because the rock is changing into a more soil- like material. Sedimentary Rocks: Soil deposits can be transformed back into rock through hardening process called induration or lithification. This forms a major category of rocks: sedimentary rocks 1- Clastic Rocks: They form when deep soil deposits become hardened as a result of pressure : 2- Carbonates: Forms when organic materials accumulate. They include: - Limestone (CaCO3): the most common type - Chalk: similar to limestone but much softer and more porous - Dolomite: similar to limestone based on mineral dolomite Metamorphic Rocks: Forms when changes happen in the minerals of the rock some of them are foliated: which means they have oriented grains. These foliations are important because the shear strength is less for shear stresses. Examples of foliated rocks: - Slate: can be split into thin sheets - Schist: strong foliated (schistosity) - Gneiss: contains banded foliation Non-foliated rocks: - Quartzite: derived from sand stone- very hard - Marble: Derived from limestone or dolomite used for decorative purpose 2.7 Rocks and Soil as Geometrials. 1. Soil and rock definitions: - Geologist: any naturally formed aggregate or mass of mineral matter - Engineers: Hard durable mattered that cannot be excavated without blasting. 2.What are the differences between Soil & Rocks? Rocks: Generally cemented Lower porosity than soil Can be found in states of decay Rock masses are discontinuous Rock are complicated and have unknown stress history Soils: Rarely cemented Soil weathering less variable Soil masses are continuous Soils greatest principle is stress Questions and Practice problems(page61) 2.1 Describe the interrelationship in the geological cycle among magma, different types of rocks and soil. Answer: The geotechnical activities are responsible for shaping and reshaping the earth. Such activities are slower in order, such as magma. Magma or the molten magma from volcanic eruption crystallizes rocks with the passage of time. These rocks break down to the soil due to environmental effect like weathering thus, this soil turns into sedimentary rocks. Therefore, we can say that the formation of rocks from the soil to rocks takes place regularly. 2.2 Which would provide a better support for large and heavy building. A diorite or a shale? Why? Answer: Diorite can be used better, since diorite is considered and igneous rock and igneous rocks have good engineering properties such as durability, satiability and abrasion resistant. These features are naturally found in igneous rocks. Shale is considered a sedimentary rock, which consists of silica and quartz, which is an unwanted property of slipping along the layer that is not recommended. 2.3 Would a tunnel excavated in a granite require less or more support than a tunnel excavated in mudstone? Why? Answer: The granite tunnel requires less support as compared to the tunnel with mudstone. Granite: is harder and tough than mudstone. Its considered an igneous rock there for its better to use it for structures. Mudstone: splits into shale when the pressure increases thus, it creates cracks. It is also a sedimentary rock. In addition, it is too soft for construction. 2.4 Fossils are imprints of rock of ancient plants and animals. What type if rock might contain fossil? Explain. Answer: Both sedimentary rocks and metamorphic rocks have fossil imprints in them where as igneous rocks are very hard in nature which means they do not show in nature. Sedimentary rocks are formed from sediments of soils & organic sediments. Which makes them soft in nature, therefore animals and plants can easily leave fossil prints in them 2.5 What type of rock is more likely to develop sinkholes? Why? Answer: Sedimentary rocks develop sinkholes. Sinkholes occur in carbonate rocks becayse these type of rocks contain limestone and carbonates. when water gets inside the soil and rocks containing the limestone get dissolved in the presence of water leaving behind sinkhole. Therefore, sedimentary rocks are more prone to sinkholes. 2.6 How does the age of rock affect its engineering characteristics? Answer: The geologic cycle is running when molten magma gets cooled and solidified. These rocks are classified into three types; igneous, sedimentary and metamorphic. When these rocks are affected by weather/heavy weathering like wind, air and water the age of rocks makes some changes in its engineering characteristics such as strength, quality and durability. Chapter 3 3.5 Surface exploration Exploratory Borings: Exploratory Borings is a common method of exploring the surface conditions by drilling a series or vertical holes in the ground & are typically 75 to 600mm (3-24 in.) in diameter & 2 to 30 m (7-100 ft) deep. Drilling in firm and dense soils. Considered the simplest drilling method. Flight auger is used or Bucker auger to produce an open hole Its inexpensive as long as its used in suitable conditions Drilling in soils prone to Caving or squeezing. Caving: The sides of the borings falling in, it is used in loose sands and gravels especially below the ground water table. Squeezing: When the soil is moving inwards, it is likely used in soft saturated slit and clays which is necessary to provide a type of lateral support inside the hole during the drilling Install casing: a temporary lining made of steel pipe, this method is necessary only if the upper soils are prone to caving Hallow stem auger: each auger has a pipe core known as stem. The drillers screw these augers in the ground. Fill borings with drilling mud or slurry, which is a mixture of bentonite or attapulgite clay and water. This material provides a pressure on the walls of the boring. Coring: Drilling through hard rock & soil. It requires different methods & equipment. Coring is used to advance the hole and obtain nearly continues undisturbed samples. After each core run the sample is brought to the ground surface and placed in a wooden core box examination and storage. Coring logs often record the rock quality designation which is the percentage of core in pieces 100mm or longer. The core recovery, which is the total sample length recovered is divided by the run length and recorded. Boring Logs: Where they record the conditions encountered. The vertical position represents depth. The vertical columns describe certain characteristics of soil and rocks encountered. Downhole logging: Drilling large diameter (500-900mm) borings so the surface conditions can be observed. This method is only suitable for above ground water table in holes not prone to caving or squeezing. What are the factors used to find Number, spacing & Depth? How large the site is? What kinds of soil or rock conditions are expected? How large or heavy is the proposed structure? Are all the areas in the site accessible to drill rigs? 3.9 In SITU Testing What are the types of in situ testing? Standard penetration Test Cone penetration Test Pressure meter test Dilatometer Becker penetration test Questions & practice problems 3.3 Describe the following Drilling method & give advantages and disadvantages of each: Solid stem auger, hallow stem auger, rotary wash& coring Answer: Solid Stem Auger: Advantages: 1.low costing method 2.Allows the sample to be collected 3.No circulating fluid 4.No casing needed Disadvantage: 1.Inefficient in loose or sandy materials 2.Ineffective water table Hollow stem auger: Advantages: 1.Used as temporary casing 2.Rapid in clayey formations 3.Collects samples in unsolidated form Disadvantages: 1.Doesn’t collect samples under water table 2.Not effective for loose or sandy soils Rotary wash: Advantages 1.Very fast method of drilling holes 2.Expensive 3.Easy availability equipments 4.High penetration capacity Disadvantage: 1.Mixing of cutting samples in bore holes 2.Samples that are collected get distributed Coring: Hard steel is used to bore holes into hard rock surfaces. Advantages: 1.Provides continues records 2.Undistributed sample 3.Sample collected are suitable for engineers Disadvantages: 1.High cost 2.Requires water sorce drilling 3.Less available equipments 3.6 Describe the advantages and disadvantages of using exploratory trench in site exploration. Answer: Advantages: 1.cost effective 2.detailed information is provided 3.large quantity of sample is available for testing Disadvantages: 1.Time period of work is long 2.Excavations of trenches below the ground water table and in rock is difficult. 3.9 instu testing: The differences between standard penetration and becker penetration? Standard: 1.oldest method and most common 2.fast and inexpensive 3.sample recovery is possible and allows direct classification is soil Becker: 1.resistance in penetration of dense and coarser soil done by counting hammer blows 2.Slow and expensive 3.Specialized equipment’s are needed 4.Number of blows required is 1 feet. CHAPTER 4 4.4 Particle size & shape - What are the characteristics & systems of soil? 1.Soil particles can have different sizes & shapes 2.They have significant effects on engineering behavior 3.ASTM system: Unified Classified System ASHTOO soil classification system -Define sieve analysis & hydrometer analysis: 1.Sieve Analysis: A sieve analysis is a laboratory test that measures the particle size distribution of a soil by passing the soil through a series of sieves. The larger sieves are defined by an opening sizes 2.Hydrometer Analysis: The hydrometer analysis works like the sieve analysis but it gives the distribution of finer particles (slit & clays) Note: The Coefficient of Uniformity: Cu= D60/D10 The Coefficient of Curvature: Cc= (D30)^2/(D10*D60) 4.5 Clay Soils Soils that consist of silt, sand or gravel particles are primarily the result of mild chemical weathering & retain a lot of chemical structures. -Type of Soils? 1.Gravel 2.Sand 3.Fine Soil -Silt -Clay -What is the Difference between Silt and Clay? 1.Silt: Individual Soils Graph Size particles Smaller than 0.07mm Too small to be seen 2.Clay: Clay particle dimensions are often smaller than 2m -Mention 3 most common Clay materials? 1. Kaolinite: -Consists of alternating silica and alumina sheets. -Does not expand appreciably when wetted therefore its used to make pottery. -Important ingredient in paper, paint and other products 2.Montmorillonite: -Belongs to the smectite group of clay minerals -The bonding between the layers is weak -Large quantity of water can enter and separate them, which causes clay to swell. - they have a specific surface up to 800 m^2/g - Bentonite: expansive clay consisting of montmorillonite and its commercially mined and sold for such purpose. 3.Illite: - Similar to montmorillonite but contains potassiumions between the layers. - Stronger than montmorillonite but weaker than Kaolinite, so illite expands slightly when wetted. What are the properties of clay? 1.The extremely large specific of clays provide more contact area between particles which makes more opportunity for various interparticle forces to develop 2.Clay particles absorb water molecules and ions, the water molecules are absorbed on particle surfaces because they are strongly attached to the particle. 3.Clay Is much different than sand since sand has a specific surface that is much smaller than clay. 4.The shear strength of a given clay at a moisture content of 50% will be less than at moister content of 10% 4.6 PLASTICITY AND THE ATTERBERG LIMITS The Atterberg Limits: In 1911, Scientist Albert Atterberg developed a series of tests to evaluate the relationship between moisture content and soil consistency. It consists of: 1. Liquid Limit test 2. Plastic Limit 3. Shrinkage limit test Plasticity: Describes the limit of the soil to the changes of moisture. When the soil changes from rigid to soft. 4.8 Organic Soil - Contains specific amount of organic matter derived from plants and animals - Soils that contain carbon & are not recently derived from plants and animals are considered inorganic. - Organic soils are much weaker and compressible than inorganic soils - Organic soils deposits features such as swamps and bogs. Swaps are larger than bogs and contain a wider variety of materials. - Plant: Peat, which is a highly organic soil derived from plants.it has a dark color black, brown or dark grey. It also has an organic matter, organic odor. A.Fiber peat B.Soft Peat CHAPTER 5 5.2 AASHTO soil classification system: Terzaghi & hogentogler developed one of the first engineering soil classification in 1928. It was intended for highway construction. 1.AASHTO systems are used for particle size distribution and atterberg limits data to assign a group classification and group index to the soil. 2.The group classification ranges from A-1 = best soils A-8 = Worst soils Group index values near 0 = good soil Group index values 20 or more = very poor soil AASHTO classification in table 5.1 determines the group classification. Group index=(F–35)[0.2+0.005(WL –40)] +0.01(F-15)(Ip-10) F= fines content ( % passing through #200 sieve) WL= Liquid Limit Ip = Plasticity index 5.3 Unified Soil Classification System(USCS) Aurthur Casagrande developed a new engineering soil classification system for the U.S. Army during world war 2. ASTM D2487 is now known as the Unified Soil Classification System(USCS). The USCS system is an all purpose system. Unlike the AASHTO system which is limited to certain projects. There is only 2 or 4 letter group symbol, ex: SM= Silty sand with gravel. Initial Classification: - Fine grained Soil - Coarse Grained Soil 1.Determine if the soil us highly organic. Composed primarily of organic material Dark brown, dark grey or black color Organic odor, especially when wet Soft consistency, high compressibility and low strength Liquid limit after oven drying is less tha 75% of the original value 2.Conduct a sieve analysis to determine particle size distribution curve. 3.Determine the percent weight passing the 3in, #4 sieve and #200 sieve. 4.Adjust the percentage of gravel, sand & fine. 5.If 5% or more of the soil passes the #200 sieve, then conduct atterberg limits tests to determine the liquid and plastic limits. 6.If the soil is fine-grained(passes the #200 sieve), then we follow the directions for fine-grained soil. Classification of Fine-Grained Soil: 1. First Letter: M = predominantly silt C = Predominantly clay O = Organic 2. Second Letter: L = Low plasticity H = high plasticity Classification of Coarse-Grained Soil: 3. First Letter: S= Predominantly Sand G = Predominantly Gravel 4. Second Letter: P = Poorly Graded W = Well- graded M = Silty C = Clayey 5.4 Visual – Manual soil classification: Distinguish Fine sand from silt & Clay: - Individual fine sand particles can be distinguished with the unaided eye, but individual silt cannot. - Clay and silt particle often clump together and look like sand. They are often separated into smaller particle when wetted - Clay are relatively strong when dried - Easily rolled into thread Distinguish Fine Clay from silt. - Silt are much smaller than 0.07mm - They have pasty consistency - Clay + silt particles are often clump together - Clay is easily rolled into thread whereas silt will fall apart when rolled 5.5 Supplemental soil classification 1.Moisture 2.Color 3.Consistency 4.Cementation 5.Structure
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'