Comprehensive Examination Requirement
To achieve candidacy for the PhD, the student must pass a departmental comprehensive examination. Typically, the student will take the comprehensive examination in the second year of study when the course work requirements have been completed. The examination must be successfully completed within three years of entrance into the PhD program. The examination is administered by the student's faculty advisor and is prepared and graded by the instructors of courses taken in the student's specialty area. Examinations are given in the following areas:
- Structures and structural mechanics
- Water resources and environmental engineering
The examination will consist of six questions, of which the student may answer three or four. The examining committee will grade a maximum of four questions as pass or fail. In order to pass the examination, the student must receive a grade of pass on at least three of the questions. Should the student fail to receive a passing grade on three questions, the student may retake the entire examination one additional time within the next year. If the student fails to pass the comprehensive examination on the second try, the student's program will be terminated.
Each examination question will consist of analytical and written parts. The examination is open book. It is expected that students will spend approximately two hours on each question: one hour in review of texts and other written materials and one hour in writing an answer to the question. A question from a past examination is given below as an example.
A 40-ft high embankment is to be constructed as a dike across a lake. The water depth during construction will be 20 ft. Side slopes of 3H to 1V and a crest width of 30 ft. are contemplated for the fill. The in-place fill will have a saturated unit weight of 135 pcf and a moist unit weight of 125 pcf. Drained strength parameters of the fill are estimated to be f = 36 degrees and c = 0. The foundation consists of a soft clay (saturated unit weight of 115 pcf) with an unconfined compressive strength increasing from 500 psf at ground surface to 1,000 psf at a depth of 30 ft. Consolidated drained tests on the clay indicate a drained friction angle of 27 degrees with no cohesion. The clay is underlain by a dense sand (N>50) to a depth of at least 120 ft.
- Define the conditions under which you would use undrained and drained parameters for the clay.
- Determine the factor of safety against failure for the given conditions immediately following construction. Use approximate stability charts or computer programs (UTEXAS2 manuals and program disk are available from the secretaries).
- Assume the computed factor of safety is very close to or slightly below one. Discuss several possible design options which would allow construction of the embankment to the same height. How would you evaluate the suitability of each option? Which would you recommend?
- Indicate in some detail what role calculated risk and the observational method could play in the construction. Would the SHANSEP method proposed by Ladd and Foote provide any benefits with regard to the observational method?