CE 360 Exam 1Questions With All Complete And Verified Solutions Graded A+.

Charles Coulomb - correct answer used the principles of calculus to determine the true position of the sliding surface in soil behind a retaining wall using the laws of friction and cohesion for solid bodies Henri Darcy - correct answer studied the permeability of sand filters and defined the term coefficient of permeability of soil Sir George Darwin - correct answer conducted lab tests to determine the overturning moment on a hinged retaining wall Joseph Boussinesq - correct answer developed the theory of stress disturbtion under load bearing areas in a homogenous, semi-infinite, elastic, and isotropic medium Albert Atterberg - correct answer defined clay size fractions as the percentage by weight of particles smaller than 2 microns in size Arthur Bell - correct answer developed relationships for lateral pressure and resistance in clay as well as bearing capacity of shallow foundations in clay Karl Terzaghi - correct answer developed the theory of consolidation for clays as we know today, known as father of modern soil mechanics Definition of Soil - correct answer Das: - an uncemented aggregate of mineral grains and decayed organic matter (solid particles) with liquid and gas in the empty spaces between the solid particles ASTM: - sediments or other unconsolidated accumulated of solid particles produced by the physical and chemical disintegration of rocks and which may or may not contain organic matter Definitions of Rock - correct answer Sowers: - any hardened material that requires drilling and blasting or similar methods of brute force for excavation ASTM: - natural solid mineral matter occurring in large masses or fragments Soil Mechanics - correct answer branch of science that deals with the study of the physical properties of soil and the behavior of soil masses subjected to various types of forces Rock Mechanics - correct answer branch of science that deals with the study of the physical properties of rock and the behavior of rock masses subjected to various types of forces Soil Engineering - correct answer application of the principles of soil mechanics to practical problems Geotechnical Engineering - correct answer application of the principles of soil and rock mechanics to practical engineering problems Advantages of Soil as a Construction Material - correct answer - readily available - relatively low cost construction techniques are simple - semi-flexible - can be modified - durable Disadvantages of Soil as a Construction Material - correct answer - non homogenous - time and space variation in properties - stress strain curve changes - dynamic loading effects - hard to get uniform characteristics - erosion - weathering - presence of rocks and boulders in weak areas - soil vs rock, where are the boundaries - selection of proper equipment Igneous Rock - correct answer formed by solidification of magma, intrusive or extrusive Sedimentary Rock - correct answer formed by compaction or cementation of small soil particles Metamorphic Rock - correct answer formed by changing the composition of rocks by heat and pressure without melting Weathing - correct answer Process of breaking down rocks by mechanics or chemical disintegration - expansion and contraction due to heating and cooling - wind - water effects, physical and chemical Transported Soils - correct answer By Wind: Aeloian - Loess - Dune sand By Water - Alluvial (transported by streams) - Marine (clays in ocean bottom, sand on beaches) - Lacustrine (formed by settling in lakes) - Glacial till (formed by action of glacial ice) Residual Soils - correct answer weathered in place Most abundant element in Earth's crust - correct answer Oxygen (46.6%), Silicon (27.7%), Aluminum (8.1%), Iron (5.0%) Soil/Rock - correct answer naturally occurring combination of minerals Mineral - correct answer solid, homogenous, naturally occurring inorganic chemical element or compound, usually having a crystalline structure two classifications, non-clay minerals and clay minerals Soil Particle Size - correct answer 1.) Coarse Gravel (4.75 to 75 mm) 2.) Fine Gravel 3.) Coarse Sand 4.) Medium Sand (all sand between 0.075 and 4.75 mm) 5.) Fine Sand 6.) Silt (0.002 to 0.075 mm) 7.) Clay (0.001 to 0.002 mm) Coarse Grained Soils - correct answer - can be seen with unaided eye - can be characterized by physical characteristics such as color, shape, and structure - engineering behavior governed by inter particle friction Fine Grained Soils (silts and clays) - correct answer - particles too small to be define by physical means (ex sieving) - made of two basic building blocks ---- silica tetrahedron ---- alumina octahedron - engineering behavior governed by mineralogy of the particles and surface area Clay Building Block #1: Silica Tetrahedron - correct answer Silicate ion: SiO4(-4) - silica tetrahedrons join to make a silica sheet Clay Building Block #2: Alumina Octahedron - correct answer - six hydroxyl (OH -1) ions surrounding a cation of Al, Fe, or MG - alumina octahedrals combine and share hydroxyl ions to form an octahedral sheet Isomorphous Substitution - correct answer When cations (other than Si or Al) are present in the tetrahedron or octahedral structure - no substation or replacement actually takes place, rather the mineral is formed with the different cation in the structure - cations of lower valence replace the natural, most common, cations - most common cations are Si, Al, Fe, and Mg Common Clay Minerals - correct answer Tetrahedral and octahedral sheets combine in various configurations to form clay minerals: 1.) kaolinite 2.) illite 3. montmorillonite Clay in Soil - correct answer Once clay are present in more than 10%, they exert a marked influence on soil's mechanics behavior: - strength is decreased - deformation is increased - permeability is decreased Clay Particles - correct answer - have flat, plate like shapes - carry net negative charge on their surface due to isomorphous substation and breaks in structural continuity at particles edges) - greater surface area = larger negative charge Specific Surface of Clay - correct answer - Kaolinite = 10 - 20 m^2/gram - Illite = 65 - 100 m^2/gram - Montmorillonite = 100 - 800 m^2/gram More surface area = greater interaction with water and therefore greater shrink/swell magnitudes Surface Area and Role of Water - correct answer - specific surface significantly affecting engineering behaviors due to differences in the amount of surface area for water to interact with - water molecules are electrically neutral, but dipolar and therefor attracted to surface of clay minerals to neutralize the charge imbalance Diffuse Double Layer - correct answer - negative surface charge of clay particles attract positive pole of water molecules in an attempt to achieve electrical neutrality - the influence of the negatively charged clay surface decreases with distance, eventually becomes negligible - the layer of attached or bound water is the diffuse double layer As specific surface area of a clay mineral increases, it causes: - correct answer - greater affinity for water - higher plasticity - increased tendency for volume change - decreased strength - greater potential for engineering problems General Remarks of Clay Particles - correct answer - volume of water in clay is often equal to or greater than volume of soils - water content or moisture content can be greater than or equal to 100% - dissolved ions disrupt clay/water structure - water is strongly attracted to clay particle surface Clay Water - correct answer - if limited water is available, all clay particles will flocculate around that limited water and will resist movement - if abundant water is available, the water will be further apart and will be less resistant to movement Engineering Significance - correct answer - clays of lower charge imbalance will exhibit a reduced tendency for volume change, decreased compressibility, and increased shear strength - clays of high charge imbalance will exhibit a greater tendency for volume change, increased compressibility, and decreased shear strength Particle Size Analysis (Mechanical Analysis) - correct answer - determination of particles sizes is the first step towards classification Two general methods: 1.) sieve analysis (for particle sizes larger than 0.075 mm in diameter, retained on #200 sieve)