Geotechnical Engineering Exam 2 Questions And Verified Correct Guaranteed Solutions.

Soil Compaction - correct answer Densification by removal of air instantaneously Soil consolidation - correct answer Removal of water in saturated conditions, time dependent Purposes of Soil Compaction - correct answer Increased shear strength, stiffness Improved quality control, erosion resistance Decreased hydraulic conductivity, liquefaction potential To determine the DRY unit weight: - correct answer 1. Measure TOTAL unit weight 2. Measure w, moisture content 3. Calculate yd = y/(1+w) Relative Density - correct answer Dr = (emax - e) / (emax - emin) Compaction Curve - correct answer X axis: Water content Y axis: Dry Unit Weight Creates an upside down parabola shape Standard Proctor Test - correct answer Plot points on compaction curve. The peak is the max yd and optimum water content Modified Proctor Test - correct answer Plot points on compaction curve. The peak will have a higher max yd and lower optimum water content than STANDARD. Line of Optimums - correct answer Line that can be drawn through multiple curves on a compaction curve plot, crosses through both peaks ZAV - correct answer Zero Air Voids line - represents completely saturated conditions (S=100) Curves cannot go past this line on the right side of the graph Max yd and optimum w depend on the - correct answer Degree of compaction The higher the energy of compaction... - correct answer The higher max yd, and the lower optimum w. Curves closer to the ZAV - correct answer Have increased dispersion in the particle arrangements Relative Compaction - correct answer RC = yd / ydmax End Result Compaction - correct answer Specifies RC and w, but does not tell how to get there Procedural Compaction - correct answer Specifies what to do, not RC Compaction Spec Trouble occurs when - correct answer Try to do end result and procedural..cannot specify both and obtain good results One Dimensional Consolidation Assumptions - correct answer 1. 1D Deformations 2. Soil Particles are incompressible 3. Soil is FULLY saturated 4. Water is incompressible Drainage in Sands - correct answer Immediate Drainage in Clays - correct answer Time Dependent Behavior of Sands - correct answer "Drained" Behavior of Clays - correct answer "Undrained" To Determine u: - correct answer 1. Calculate Z = z/Hd 2. Calculate T = Cvt/Hd^2 3. Use Isochrone Chart with Z and T to find U/Uo 4. U/Uo x Change in Effective Stress = U Average Degree of Consolidation - correct answer U = delta c,t / delta c Determine Settlement at Time t - correct answer 1. Calculate ultimate settlement (can use log stress vs void ratio curve) 2. Calculate T = Cvt/Hd^2 3. Get Ut from Average Consolidation Curve 4. Calculate delta c,t = Ut/ultimate settlement Double Drainage - correct answer Hd = H/2 Single Drainage - correct answer Hd = H Prevent Excessive Settlement by - correct answer 1. Deeper foundation 2. Floating foundation 3. Preloading or surcharge 4. Preloading or surcharge with vertical drains 5. Lower water table (same as applying a load) Terzaghi"s 1D Assumptions - correct answer 1. Saturated Soil 2. Particles and water are incompressible 3. Compression and flow are 1D 4. Void ratio vs sigma response is linear 5. Darcy's law is valid 6. Homogenous Soil 7. Soil properties are constant with time