ABSTRACT

CONTENTS 1.1 Introduction ........................................................................................................................... 2 1.2 Soil Classification.................................................................................................................. 2

1.2.1 Mechanical Analysis................................................................................................. 2 1.2.2 Atterberg Limits........................................................................................................ 4 1.2.3 Unified Soil Classification System ......................................................................... 6

1.3 Effective Stress Concept....................................................................................................... 6 1.4 Strength of Soils .................................................................................................................... 9

1.4.1 Drained and Undrained Strengths ........................................................................ 9 1.4.2 Triaxial Tests............................................................................................................ 10

1.4.2.1 Triaxial Testing of Rocks ........................................................................ 11 1.4.2.2 Selection of Triaxial Test Type Based on

the Construction Situation...................................................................... 11 1.4.2.3 Computation of Strength Parameters Based

on Triaxial Tests ....................................................................................... 13 1.4.3 Unconfined Compression Test ............................................................................. 15

1.5 Compressibility and Settlement ....................................................................................... 16 1.5.1 Estimation of Immediate Settlement in Soils ..................................................... 17

1.5.1.1 Elastic Properties and In Situ Test Parameters ................................... 19 1.5.2 Estimation of Foundation Settlement in Saturated Clays ................................ 20

1.6 Soil Densities and Compaction......................................................................................... 25 1.6.1 Bulk Unit Weight .................................................................................................... 25 1.6.2 Dry Unit Weight ..................................................................................................... 26 1.6.3 Saturated Unit Weight ........................................................................................... 26 1.6.4 Submerged (Buoyant) Unit Weight ..................................................................... 27 1.6.5 Soil Compaction ...................................................................................................... 27

1.6.5.1 Laboratory Compaction .......................................................................... 27 1.6.5.2 Evaluation of Field Compaction............................................................ 29

1.7 Finite Element Concepts Used in Modeling of Earthen Structures ........................... 31 1.7.1 Finite Element Approach....................................................................................... 31 1.7.2 Finite Element Formulation .................................................................................. 31 1.7.3 Equilibrium and Compatibility Conditions ....................................................... 33

1.8 Common Methods of Modeling the Yielding Behavior of Soils................................. 35 1.8.1 Modified Cam-Clay Model ................................................................................... 36

1.8.1.1 Isotropic Consolidation of Clays ........................................................... 36 State of Clay

1.8.1.3 Stress-Strain Relations for Yielding Clays........................................... 39 1.8.2 Cap Model................................................................................................................ 39 1.8.3 Nonlinear Elastic Stress-Strain Relations ........................................................... 42

1.8.3.1 Evaluation of Nonlinear Elastic Parameters ....................................... 42 1.8.3.2 Evaluation of Gmax from Standard Penetration Tests ...................... 43

1.8.4 Concepts of Stress Dilatancy Theroy for Granular Soils.................................. 43 References ..................................................................................................................................... 44

Geotechnical engineering is a branch of civil engineering in which technology is applied in the design and construction of structures involving geological materials. Earth’s surface material consists of soil and rock. Of the several branches of geotechnical engineering, soil and rock mechanics are the fundamental studies of the properties and mechanics of soil and rock, respectively. Foundation engineering is the application of the principles of soil mechanics, rock mechanics, and structural engineering to the design of structures associated with earthen materials. On the other hand, rock engineering is the corresponding application of the above-mentioned technologies in the design of structures associated with rock. It is generally observed that most foundation types supported by intact bedrock present no compressibility problems. Therefore, when designing common foundation types, the foundation engineer’s primary concerns are the strength and compressibility of the subsurface soil and, whenever applicable, the strength of bedrock.