Soil Behavior

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Soil Behavior posted by member7_php on 2/27/2009

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Abstract/Syllabus

Courseware/Lectures

Test/Tutorials

Soil Behavior

Spring 2005

Canisteo clay loam, a soil profile from Minnesota. (Image courtesy of the USDA.)

Course Highlights

This class features some of the readings from the class, and a complete set of lecture notes.

Course Description

This class presents a detailed study of soil properties with emphasis on interpretation of field and laboratory test data and their use in soft-ground construction engineering. Topics to be covered include: consolidation and secondary compression; basic strength principles; stress-strain strength behavior of clays, emphasizing effects of sample disturbance, anisotropy, and strain rate; strength and compression of granular soils; and engineering properties of compacted soils. Some knowledge of field and laboratory testing is assumed for all students.

Syllabus

Course Description

Conduct of Subjects

Classes run as combination of regular lectures and class discussions.
Reading assignments include class notes and papers.
Do not consult any prior homework problems or exams.
Homework problems, class problems, and class discussion count 30%.
One 2-hour mid-term exam counts 30%.
One three-hour final exam counts 40%.

Lecture Topics

Introduction (Mostly Review of 1.361)

Scope of Course
Soil Composition
Water Absorption, Clay-water Forces, and Measurement of Soil Suction
Soil Structure
Classification Tests and USC System

Basic Strength Principles and Stress-Strain Behavior of Simple Clay; Soil Modeling

Types of Triaxial Tests and Strength Principles
Mechanisms of Volume (Pore Pressure) Change in Clays and Sands
Behavior of Normally Consolidated Simple Clay (Laddite)
Behavior of Overconsolidated Simple Clay (Laddite)
Hvorslev Parameters and Extension Tests
Modified Cam-Clay Model

Consolidation Behavior of Saturated Soils

Introducation (K0 Trends and Measurement, Role of Oedometer Test)
Amount of 1-D Settlement (Preconsolidation Mechanisms and Measurement, Disturbance, Creep, etc.)
Rate of 1-D Consolidation
Secondary Compression (C_α/C_c, Hypothesis A vs. B)
2-D and 3-D Settlement (Initial, Amount and Rate of Consolidation)
Problem Soils (Sensitive, Organic, Expansive, Collapsing, Varved, etc.)

Stability Problems and Drained Strength Analyses

Overview (Classes of Probems, Types of Analyses and Corresponding Strength Parameters for UU, CU and CD Cases)
Effective Stress Parameters for Drained Analyses (Measurement and Problem Soils)

Undrained Strength-Deformation Behavior of Saturated Clays and Undrained Strength Analyses

Conventional Practice for UU Case (In Situ and Lab Techniques)
Sample Disturbance
Stress System (σ₂ and Anisotropy)
Overview of MIT-E3 Model
Time (Strain Rate and Creep)
Conclusions and Special Problems
Staged Construction (CU Case)

Strength-Deformation Behavior of Cohesionless Soils

Strength Components and Steady-state Line
Effects of Density, Confinement and σ₂ on Drained and Especially Undrained Behavior
Effects of Sand Structure (Anisotropy, Stress History, Heterogeneity etc.)
MIT-S1 Model Overview

Compacted Clays

Compaction Process (Fundamentals)
Structure and Engineering Properties
Effective Stress with S < 100%
Constitutive Modeling

Miscellaneous

Special Lecture on Precompression, Vertical Drains, and Case Histories
Mid-term Exam and Discussion of Home Problems

Comparison of Laboratory and In Situ Testing: Complimentary, Not Competing

Course syllabus.
LAB (oedometer, triaxial, etc.)	IN SITU (FV, CPTU, DMT, SBPT, etc.)
Advantages Well defined boundary conditions → well defined soil properties via interpretation with continuum mechanics. Can control loading and drainage conditions → property variation with stress path and drainage. Known soil type and features.	Advantages Testing soil at in situ conditions and usually less affected by disturbance. Usually lower cost, more rapid and some field tests (CPTU) can provide continuous profile. Best suited for spatial variability → mean trends + scatter about mean.
Limitations Sample disturbance - Affects properties (especially cohesionless soils) - Misleading spatial variations. Discontinuous data on small fraction of soil High cost	Limitations Ill-defined boundary conditions (stress-strain-drainage) - Need empirical correlations for soil properties May not know soil type

Calendar

The calendar of the class is presented here. In the Lecturer column, AJW is Andrew Whittle, and LCJ is Lucy Jen.

Course schedule.
SES #	LECTURERS	TOPICS	KEY DATES
1	AJW and LCJ	Overview, Organization, Soil Composition Clay-Water Forces
2	LCJ	Clay-Water Forces, Interparticle Forces
3	LCJ	Strength Generation in Soils Soil Structure
4	LCJ	Basic Strength Principles Simple Clay (Laddite) - NC	Homework problem 1 due
5	LCJ	Laddite - OC Hvorslev Parameters, SB Surface
6	AJW	Plasticity Mechanisms Controlling Compressibility of Clays	Homework problem 2 due
7	AJW	Mechanisms Controlling Compressibility of Clays
8	AJW	K0 and Stress History Stress History Profiling	Homework problem 3 due
9	AJW	Rates of Consolidation Hydraulic Conductivity
10	AJW	2° Compression	Mini problem on stress history due
11	AJW	Non-Linear Consolidation 2D/3D Effects
12	LCJ	Problem Soils - 1 Structured Clays, Varved Clays and Peat
13	LCJ	Problem Soils - 2 Expansive Soils, Residual Soils
14	LCJ	Embankments on Peat Surcharging to Control 2° Compression	Homework problem 4 due
15	LCJ	Strength 1A and 1B Strength 1C
16	LCJ	Strength 1C and IIA Strength IIB
17	LCJ	Strength IIB	Mini problem 1 due
18	LCJ	Strength IIC - Sample Disturbance
19	LCJ	Strength IID
20	LCJ	Strength IID Strength IID, IIE and IIF	Mini problem 2B due
21	AJW	Shear Modes Clay Anisotropy and E3 Soil Model
22	AJW	Sands	Homework problem 5 due
23	AJW	Sands (cont.)
24	AJW	Compacted Clay
25	AJW	Compacted Clay (cont.)

Readings

This section contains documents created from scanned original files, which are inaccessible to screen reader software. A "#" symbol is used to denote such documents.

Foott, R., and C. Ladd. "Undrained Settlement of Plastic and Organic Clays." Journal of the Geotechnical Engineering Division 107, no. GT8 (August 1981): 1079-1094.

Jamiolkowski, M., C. Ladd, J. Germaine, and R. Lancellotta. "New Developments in Field and Laboratory Testing of Soils." Proceedings of the 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco, 1995.

Koutsoftas, D., and C. Ladd. "Design Strengths for an Offshore Clay." Journal of Geotechnical Engineering 111, no. 3 (March 1985)

Ladd, C., R. Foott, K. Ishihara, F. Schlosser, and H. Poulos. "Stress-Deformation and Strength Characteristics." Proceedings of the 9th International Conference on Soil Mechanics and Foundation Engineering, Tokyo, 1977.

Ladd, C., and R. Foott. "New Design Procedure for Stability of Soft Clays." Joumal of the Geotechnical Engincening Dision 100, no. GT (July 1974): 763-786.

Ladd, C. "Stress-Strain Behavior of Saturated Clay and Basic Strength Principles." Research in Earth Physics, Research Report R64-17, Phase Report 1, April 1964. (PDF - 2.3 MB)^#

Ladd, C., and E. Kinner. "The Strength of Clays at Low Effective Stress." Research in Earth Physics, Research Report R67-4, Phase Report 8, January 1967.