What Is Rock Anisotropy (Without Respect to the Properties of Discontinuities)

CEE 437 Engineering Geology I

Final Exam, June 11,2002

Instructions: This final exam will be given 4:30-6:20 p.m. Tuesday, Jun. 11, 2002. The exam will be closed book, but feel free to discuss the questions with anyone including the instructors through June 10th. Answers to e-mailed questions will be e-mailed to all students.

Each of the questions below should take no more than 10 to 15 minutes to answer. Concise, brief answers are encouraged - grading will be based on an indication of comprehension of the material.

1. How do fractures effect rock strength, deformability, and anisotropy? Estimate the range of rock mass modulus for RMR values of 10,50, and 90. Compare Hoek-Brown, Barton-Bandis, and Mohr-Coulomb strength envelopes for intact rock and rock with a fracture frequency of 30/meter. (15 points)

1. Define Mode 1, Mode 2, Mode 3 fractures, and stylolites. Discuss the difference between different types of fractures for their effect on groundwater flow and transport, foundation deformability, and slope stability. (10 points)

1. Describe the difference between the Terzaghi (1964) and Mauldon&Mauldon(1997) corrections for fracture orientation bias. (5 points)

1. Describe the pattern of fracturing which occurs in a fold – how is the fracturing different at the crest, flank, and base. Where do Mode 1 fractures occur, and where do Mode 2 fractures occur ? What are their orientations? (5 points)

1. Define the possible slope failure modes in intensely fractured rock, rock with a single extensive fracture system, and rock with three fracture systems. Describe the effect of groundwater, fracture orientation, fracture roughness, and infilling on failure modes. (10 points)

1. Draw a landslide zone, illustrating the occurrence of different types of fractures, scarps, and talus. What signs would indicate incipient slope instability? What signs would indicate a historical slide ? What instrumentation can be used to monitor slope movement? (10 points)

1. Define P, S, and Surface waves. How are these waves used to calculate earthquake epicenter location, magnitude, and possible engineering impacts from earthquakes. Discuss the transfer of seismic waves through a layered geology consisting of a soft fractured rock overlain by a stiff, over-consolidated sediment, with organic soils at the surface. (10 points)

1. Describe the geologic settings that would occur in the vicinity of a recent volcano – both soils and rock. (10 points)

1. Draw of typical Puget Sound glacial geologic setting, illustrating the glacial facies and their engineering significance. Describe the grain size distribution, grading, heterogeneity and relative density of these facies. (10 points)

1. Prepare a table comparing constituents (e.g., clay, silt, sand, gravel), density, anisotropy, heterogeneity, sensitivity, and strength of the following soil deposits: alluvium, colluvium, lacustrine sediments, glacial sediments, aeolian sediments, marine sediments, pedogenic soils, and organic soils. (15 points)