Week 1 Introduction to Course and Review CE427 PDF

CE427 Foundation Engineering  CE427 Week 1 CE427 Foundation Engineering 1. Introduction to course 2. Review on: a. Index classif...

CE427 Foundation Engineering  CE427 Week 1 CE427 Foundation Engineering 1. Introduction to course 2. Review on: a. Index classification of soil b. Soil classification by: Engr. Vera Karla Caingles Engr. Christian Linares WHAT IS SOIL? CE427 CE427 SOIL is defined as the Foundation Engineering uncemented aggregate of mineral grains and decayed organic matter (solid particles) along with the liquid and gas by: that occupy the empty spaces Engr. Vera Karla Caingles Engr. Christian Linares between the solid particles. WHAT IS FOUNDTION ENGINEERING? CE427 Foundation engineering is the CE427 Foundation application and practice of the fundamental principles of soil mechanics and rock Engineering mechanics (i.e., geotechnical engineering) in the design of foundations of various structures. These foundations include those of columns and walls of buildings, bridge abutments, embankments, and others. It also involves the analysis and design of earth-retaining by: Engr. Vera Karla Caingles structures such as retaining walls, sheet-pile Engr. Christian Linares walls, and braced cuts. WHAT IS FOUNDTION ENGINEERING? CE427 Foundation engineering is a CE427 Foundation clever combination of soil Engineering mechanics, engineering geology, and proper judgment derived from past by: experience. To a certain extent, Engr. Vera Karla Caingles Engr. Christian Linares it may be called an art. The design of foundations of structures such as buildings, bridges, and dams generally requires a CE427 knowledge of such factors as: CE427 Foundation (a) the load that will be transmitted by the superstructure Engineering to the foundation system, (b) the requirements of the local building code, (c) the behavior and stress-related deformability of soils that will support the foundation system, and by: Engr. Vera Karla Caingles Engr. Christian Linares (d) the geological conditions of the soil under consideration.  The geotechnical properties of a soil can be CE427 assessed through: CE427 Foundation Proper laboratory testing Proper field testing Engineering ✓ grain-size distribution, ✓ Field density test, ✓ plasticity, ✓ Borehole test, ✓ compressibility, ✓ Plate load test, etc.. ✓ shear strength, etc.. by: Engr. Vera Karla Caingles Engr. Christian Linares  CE427 CE427 Foundation REVIEW: Engineering GEOTECHNICAL PROPERTIES OF SOIL by: Engr. Vera Karla Caingles Engr. Christian Linares Geotechnical Properties of SOIL CE427 Foundation Engineering INDEX PROPERTIES OF SOILS The various properties of soil which would be considered as index properties are: 1. The specific gravity 2. The size and shape of particles 3. The relative density or consistency of soil Geotechnical Properties of SOIL CE427 Foundation 1. Grain-Size Distribution Engineering The grain-size distribution of coarse- grained soil is generally determined by means of sieve analysis. For a fine- grained soil, the grain-size distribution can be obtained by means of hydrometer analysis. -vkis caingles Geotechnical Properties of SOIL CE427 Foundation 1. Grain-Size Distribution Engineering ❑ sieve analysis Sieve analysis is conducted by taking a measured amount of dry, well-pulverized soil and passing it through a stack of progressively finer sieves with a pan at the bottom. The amount of soil retained on each sieve is measured, and the cumulative percentage of soil passing through each is determined. This percentage is generally referred to as percent finer. Geotechnical Properties of SOIL CE427 Foundation 1. Grain-Size Distribution Engineering ❑ sieve analysis Geotechnical Properties of SOIL CE427 Foundation 1. Grain-Size Distribution Engineering ❑ hydrometer analysis Hydrometer analysis is based on the principle of sedimentation of soil particles in water. This test involves the use of 50 grams of dry, pulverized soil. A deflocculating agent is always added to the soil.  Geotechnical Properties of SOIL CE427 Foundation ❑ Distribution Curve Engineering A particle-size distribution curve can be used to determine the following four parameters for a given soil: 1. Effective size (D10): This parameter is the diameter in the particle-size distribution curve corresponding to 10% finer. The effective size of a granular soil is a good measure to estimate the hydraulic conductivity and drainage through soil. 2. Uniformity coefficient (Cu): This parameter is defined as: where D60 = diameter corresponding to 60% finer.  Geotechnical Properties of SOIL CE427 Foundation ❑ Distribution Curve Engineering 3. Coefficient of gradation (Cc): This parameter is defined as: 4. Sorting coefficient (S0): This parameter is another measure of uniformity and is generally encountered in geologic works and expressed as: Geotechnical Properties of SOIL CE427 Foundation ❑ Distribution Curve Engineering 1. Curve I represents a type of soil in which most of the soil grains are the same size. This is called poorly graded soil. 2. Curve II represents a soil in which the particle sizes are distributed over a wide range, termed well graded. A well-graded soil has a uniformity coefficient greater than about 4 for gravels and 6 for sands, and a coefficient of gradation between 1 and 3 (for gravels and sands). A flat S- curve represents a soil which contains the particles of different sizes in good proportion. Geotechnical Properties of SOIL CE427 Foundation ❑ Distribution Curve Engineering 3. Curve III represents a soil might have a combination of two or more uniformly graded fractions. This type of soil is termed gap graded. A curve with a hump in which some of the intermediate size particles are missing. Geotechnical Properties of SOIL CE427 Foundation 2. Size Limits for Soil Engineering Several organizations have attempted to develop the size limits for gravel, sand, silt, and clay on the basis of the grain sizes present in soils. Geotechnical Properties of SOIL CE427 Foundation 3. Atterberg Limits Engineering - a swedish scientist, developed a method to describe the consistency of fine-grained soils with varying moisture contents. ✓ At a very low moisture content, soil behaves more like a solid. ✓ When the moisture content is very high, the soil and water may flow like a liquid. ✓ The behavior of soil can be divided into four basic states: solid, semisolid, plastic, and liquid ✓ Atterberg limits are the limits of water content used to define soil behavior.  CE427 Geotechnical Properties of SOIL Foundation Engineering 4. Liquidity Index The relative consistency of a cohesive soil in the natural state can be defined by a ratio called the liquidity index, which is given by The in situ moisture content for a sensitive clay may be greater than the liquid limit. These soils, when remolded, can be transformed into a viscous form to flow like a liquid. Soil deposits that are heavily overconsolidated may have a natural moisture content less than the plastic limit. In this case Geotechnical Properties of SOIL CE427 Foundation 5. Activity of soil Engineering Skempton (1953) observed that the plasticity index of a soil increases linearly with the percentage of clay-size fraction (% finer than 2 mm by weight) present. The correlations of PI with the clay-size fractions for different clays plot separate lines. This difference is due to the diverse plasticity characteristics of the various types of clay minerals. On the basis of these results, Skempton defined a quantity called activity, which is the slope of the line correlating PI and % finer than 2 mm. This activity may be expressed as: Geotechnical Properties of SOIL CE427 Foundation 5. Activity Engineering Geotechnical Properties of SOIL CE427 Foundation 6. Volume-weight Relationship Engineering (a) Soil element in natural state; (b) three phases of the soil element  -vkis.caingles Geotechnical Properties of SOIL -a.abad -d.bas CE427 Foundation 6. Volume-weight Relationship Engineering  CE427 Geotechnical Properties of SOIL Foundation Engineering 7. SOIL CLASSIFICATION SYSTEMS The two major classification systems presently in use are: (1) American Association of State Highway and Transportation Officials (AASHTO) System (2) Unified SoilClassification System (also ASTM). Geotechnical Properties of SOIL CE427 Foundation 7. SOIL CLASSIFICATION SYSTEMS : AASHTO Engineering - Originally proposed by the Highway Research Board’s Committee on Classification of Materials for Subgrades and Granular Type Roads (1945) - Soils can be classified according to eight major groups, A-1 through A-8, based on their grain-size distribution, liquid limit, and plasticity indices. Soils listed in groups A-1, A-2, and A-3 are coarse-grained materials, and those in groups A-4, A-5, A-6, and A-7 are fine-grained materials. - Peat, muck, and other highly organic soils are classified under A-8. They are identified by visual inspection -vkis caingles Geotechnical Properties of SOIL CE427 Foundation 7. SOIL CLASSIFICATION SYSTEMS: AASHTO Engineering For qualitative evaluation of the desirability of a soil as a highway subgrade material, a number referred to as the group index has also been developed. The higher the value of the group index for a given soil, the weaker will be the soil’s performance as a subgrade. A group index of 20 or more indicates a very poor subgrade material.  -vkis.caingles Geotechnical Properties of SOIL -a.abad -d.bas CE427 Foundation 7. SOIL CLASSIFICATION SYSTEMS: AASHTO Engineering  -vkis.caingles Geotechnical Properties of SOIL -a.abad -d.bas CE427 Foundation 7. SOIL CLASSIFICATION SYSTEMS: AASHTO Engineering Geotechnical Properties of SOIL CE427 Foundation 7. SOIL CLASSIFICATION SYSTEMS: USCS Engineering - Originally proposed by A. Casagrande in 1942 and was later revised and adopted by the United States Bureau of Reclamation and the U.S. Army Corps of Engineers - The system is currently used in practically all geotechnical work. Geotechnical Properties of SOIL CE427 Foundation 7. SOIL CLASSIFICATION SYSTEMS: USCS Engineering  CE427 Foundation Engineering  CE427 Foundation Engineering  CE427 CE427 Foundation Historical Perspective of Engineering Soil Mechanics and Geotechnical Engineering by: Engr. Vera Karla Caingles Engr. Christian Linares  Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering The record of the first use of soil as a construction material by mankind is lost in antiquity. In true engineering sense, there is no ‘Geotechnical Engineering’ prior to the 18th Century. One of the most famous example of problems related to soil bearing capacity and foundations in the construction of structures prior to 18th century is the Leaning Tower of Pisa in Italy. The construction of the Tower began in 1173 A.D. and last over 200 years. Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering The Leaning Tower of Pisa, Italy. Morning, 1 March 2004. SW view Height: 54 m; Max tilt: 5 m out of plumb Tilt direction: E, N, W, and S. Weight: 15,700 tons; Base: φ = 20 m; Reason: a weak clay layer at 11 m depth Solution: excavation of soil from north side for about 70 tons  Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering Tilting of Garisenda Tower (Left) in Bologna, Italy (Built in 12th Century)  Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering Study of soil behavior in a more methodical manner in the area of geotechnical engineering started in the early part of the 18th century, and last to 1927. The development of soil mechanics can be divided into four phases, according to Skempton(1985): 1. Preclassical period (1700-1776) - rough classification of soils 2. Classical soil mechanics Phase I (1776-1856) - started from French scientist Coulomb’s presentation on determining the sliding surface in soil behind a retaining wall; ended by the publication of Rankine’s paper on earth lateral pressure. Rankine’s theory is a simplification of Coulomb’s theory.  Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering 3. Classical soil mechanics –Phase II (1856-1910) - started from the publication of a paper on the permeability of sand filters by French engineer Darcy in 1856. 4. Modern soil mechanics (1910-1927) - marked by a series of important studies and publications related to the mechanic behavior of clays, most noticeable, > Atterberg(1911) on consistency of clayey soils, the Atterberg limits; > Bell (1915) on lateral pressure and resistance of clays; > Terzaghi(1925) on theory of consolidation for clays.  Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering Geotechnical Engineering after 1927 The development of Geotechnical Engineering as a branch of Civil Engineering is absolutely impacted by one single professional individual –Karl Terzaghi(1883-1963). His contribution has spread to almost every topic in soil mechanics and geotechnical engineering covered by the test book: > Effective stress > Elastic stress distribution > Consolidation settlement > Shear strength Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering KARL TERZAGHI Born: October 2, 1883 in Prague Died: October 25, 1963 in Winchester, Massachusetts He was married to Ruth D. Terzaghi, a geologist. He won the Norman Medal of ASCE four times (1930, 1943, 1946, and 1955). He was given nine honorary doctorate degrees from universities in eight different countries. He started modern soil mechanics with his theories of consolidation, lateral earth pressures, bearing capacity, and stability.  Historical Perspective of Soil Mechanics and CE427 Geotechnical Engineering Foundation Engineering “Few people during Terzaghi’s lifetime would have disagreed that he was not only the guiding spirit in soil mechanics, but that he was the clearing house for research and application throughout the world.” Ralph B. Peck is an eminent civil engineer specializing in soil mechanics. He was awarded the -Ralph B. Peck National Medal of Science in 1975  CE427 References: Foundation Engineering Das, B. (2016). Principles of Foundation Engineering, 8th edition. Cengage Learning Murthy, V. (2007). Advanced Foundation Engineering. CBS Publishers & Distributors, New Delhi