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CIVE 655 - ADVANCED SOIL MECHANICS

Fall 2012

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Geotechnical and Geoenvironmental Engineering Program

Department of Civil and Environmental Engineering

Colorado State University

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Credit Hours: 3

Prerequisite: CIVE 355 - Introduction to Geotechnical Engineering or equivalent

CRN: 66676

Time: M,W,F: 9:00 – 9:50 am

Location: Room B3, Engineering Building

Instructor: Prof. Shackelford, A 217 ENGRG (e-mail: shackel@engr.colostate.edu)

Office Hours: MW: 8 – 9 am; WF:11 am – noon; By arrangement.

______________________________________________________________________________ Course description: The course will be divided approximately equally in half, with the first half of the

course focused primarily on advanced topics in shear strength, and the second half focused primarily on

advanced topics in consolidation. After a brief review of drained and undrained shear strength of soils

under traditional triaxial compression testing, the advanced topics to be covered in shear strength will

include modified Mohr-Coulomb diagrams, including p-q diagrams, stress paths, triaxial extension and

triaxial compression tests, rotation of principle planes, drained and undrained failure at principle stress

difference versus principal stress ratio, and inherent (material) and stress induced anisotropy. In

consolidation, the components of settlement and the effect of submergence on ultimate consolidation

settlement will be covered. Then, traditional Terzaghi, small-strain consolidation theory will be extended

to cover non-rectangular stress surfaces and special conditions, the principal of superposition for multiple

stress surfaces, multi-layered compressible soil profiles and partially draining boundary conditions, time-

dependent (ramp) loading, radial drainage and the use of wick drains, consolidation resulting combined

vertical and radial drainage under vertical loading, and application of finite-difference methods to time-

rate consolidation problems.

Text: Soil Mechanics by Lambe and Whitman, John Wiley and Sons, Inc., 1969

Additional Class Materials: Reading of classic papers on the subject will be assigned throughout the

semester.

Course Objectives: Upon successful completion of this course, the student will be able to determine the

appropriate type of soil shear strength to be used for analysis and design of geotechnical structures (e.g.,

slopes, foundations, earth retaining structures, etc.) and to evaluate the effects of submergence, partial

draining boundaries, time-dependent loading, and radial drainage on the consolidation properties and the

time-rates of consolidation of compressible soils for a wide variety of practical problems.

Instructional Methodology: The class will meet as a single group three days a week for lecture.

Mode of Delivery: Traditional lectures using transparencies and boards with handouts.

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Methods of Evaluation: Periodic homework assignments and quizzes will be given throughout the

course. Two equally weighted exams, a mid-term exam covering the first half of the course on shear

strength and a final exam covering the second-half of the course on consolidation, will be used to evaluate

student performance and as a basis for assigning grades. The grade distribution will be as follows.

Homework and Quizzes 20%

Mid-term Exam 40%

Final Exam 40%

Total 100%

I will use straight average (except for exams in cases where class average is too low), and the +/- grading

system as follows:

Straight Scale Grading

96.7 % ≤ A+ ≤ 100 %

93.3 % ≤ A < 96.7 %

90.0 % ≤ A– < 93.3 %

86.7 % ≤ B+ < 90.0 %

83.3 %≤ B < 86.7 %

80.0 % ≤ B– < 83.3 %

76.7 % ≤ C+ < 80.0 %

70.0 % ≤ C < 76.7 %

60.0 % ≤ D < 70.0 %

F < 60.0 %

Course Topics/Weekly Schedule:

Week Topics

1 Review of shear strength under traditional triaxial compression TC conditions; effective stress

and total stress shear strength; drained and undrained shear strength; back-pressure saturation

2 Stress-strain soil behavior under drained and undrained conditions for traditional triaxial

compression loading conditions; principal stress and Mohr's circle by origin of planes; concept

of pole point

3 Modified Mohr-Coulomb diagrams; stress paths for drained and undrained traditional triaxial

compression loading conditions

4 Stress-strain and shear strength under drained and undrained loading conditions for non-

traditional triaxial compression and triaxial extension loading conditions

5 Generalized drained soil behavior; principal stress difference vs. principal stress ratio as failure

criterion

6 Pore pressure parameters B, D, and A; generalized undrained soil behavior; principal stress

difference vs. principal stress ratio as failure criterion

7 Rotation of principal planes; SHANSEP design method for staged construction of

embankments

8 Material (inherent) and stress-induced anisotropy

9 Types of settlement; stress-strain curves for 1-D consolidation settlement; aspects of secondary

consolidation; submergence correction for large-strain ultimate consolidation settlement

Mid-Term Exam: Wednesday, Oct. 22: Covers material in weeks 1-8.

10 Terzaghi's theory of consolidation; extension of theory to cover non-rectangular stress surfaces

and special conditions; principal of superposition for complex stress surfaces

**************Continued on next page**************

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Course Topics/Weekly Schedule (continued):

Week Topics

11 Consolidation for multi-layered compressible soil profiles and partially draining boundary

conditions

12 Time-dependent loading; radial drainage and wick drains; vertical consolidation under

combined vertical and radial drainage

13 Finite difference method; explicit and implicit finite difference formulations and Crank-

Nicholson solution methodology for Terzaghi's 1-D theory of consolidation

14 Explicit and implicit finite difference formulations and solution methodology for time-

dependent loading and partially drainage boundary conditions

15 Explicit and implicit finite difference formulations and solution methodology for radial

drainage with time-dependent loading and combined radial and vertical drainage with time

dependent loading

16 Final Exam: Thursday, Dec. 13, 7:30-9:30 am: Covers material in weeks 9-15

SUGGESTED READING FROM SOIL MECHANICS by LAMBE AND WHITMAN, 1969.

Shear Strength

Chapter Section(s) Page(s) Topic(s)

8 4 105-107 principal stresses - Mohr's Circle

8 5 107-112 p-q diagrams

8 6 112-115 stress paths

9 1-5 116-121 tests to measure stress-strain (S-S) properties

10 4 127-135 S-S behavior during triaxial compression

11 1-5 137-149 shear strength of dry cohesionless soil

12 1 151-153 concepts from theory of elasticity

12 3, 4 158-160 triaxial shear behavior

20 3, 4 301-302 drained behavior - triaxial shear

21 1-7 304-316 drained shear strength

22 2, 3 324-326 drained S-S triaxial shear

26 1 391-394 pore pressures in undrained conditions

26 3 396 B-parameter

4 396-397 D-parameter

5,6 397-401 A-parameter

8 404-405 unsaturated soil

28 1-8 423-438 drained and undrained S-S behavior

29 1-9 439-453 undrained shear strength

30 1-5 455-463 S-S for undrained conditions

Consolidation

Chapter Section(s) Page(s) Topic(s)

9 1 116 oedometer test

10 3 123-127 S-S behavior

12 2 153-158 S-S behavior

20 2 296-301 S-S behavior

22 1 318-324 S-S behavior

26 2 394-396 pore pressures

27 1-7 406-420 consolidation theory