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this is the presentation of Dr. P. K. Basudhar, Dept of Civil Engineering, IIT Kanpur. it is good material to have a basic sight about soil mechanics and foundation. FOUNDATIONS • WHAT ARE FOUNDATIONS? • TYPES OF FOUNDATIONS – SHALLOW FOUNDATIONS – DEEP FOUNDATIONS • MAIN PROBLEM IN THE DESIGN – TO PREVENT SETTLEMENT • TOTAL SETTLEMENT • DIFFERENTIAL SETTLEMENT
An Overview of Soil Mechanics Dr P K Basudhar Dept of Civil Engineering IIT Kanpur Soil Problems & Solutions A Preview of Soil Behavior Pioneers in Soil Mechanics WHERE ? CIVIL ENGINEER ENCOUNTERS • SOIL AS A – FOUNDATION – CONSTRUCTION MATERIAL • SOIL RETAINING • SPECIAL PROBLEMS SOIL FOUNDATIONS • WHAT ARE FOUNDATIONS? • TYPES OF FOUNDATIONS – SHALLOW FOUNDATIONS – DEEP FOUNDATIONS • MAIN PROBLEM IN THE DESIGN – TO PREVENT SETTLEMENT • TOTAL SETTLEMENT • DIFFERENTIAL SETTLEMENT SHALLOW FOUNDATIONS • Structural loads are carried by the soil directly under the structure DEEP FOUNDATIONS • Used to carry ca y the t e loads to firm soil at p some depth Classic case of bad foundation • Fig Figg shows the Palacio de las Bellas Artes, Mexico City • The m differential settlement between the street and the building on the right necessitated the steps which were added as the settlement occurred • The general subsidence of this part of the city is m • (Photograph compliments of Raul Marsal) Example of Shallow foundations • Fig shows the MIT students centre • Mat foundation • Floatation technique Main Factors Just how deep into the soil should the building be placed? Would the excavation have to be enclosed by a wall duringg construction to p prevent cave cave ins of soil? Would it be necessary to lower the water table in order to excavate and construct the foundation and, if so, so what h t means me ns should sho ld be used sed to accomplish omplish this lowering of the ground water (dewatering)? Was tthere e e a da danger ge o of da damage age to adjace adjacentt b buildings? d gs? How much would the completed building settle and would it settle uniformly? For what stresses and what stress distribution should the mat of the building be designed? Example of Deep foundations • MIT material centre has deep pp pile foundation • Reasons – Basement space not desirable – No sand and gravel at the h site i – Not to disturb underground utilities • Point bearing pile • Friction pile p • Augering 4th Consequence When the load applied to a soil is suddenly changed, the change is carried by jointly by the pore fluid and by the mineral skeleton The change in pore pressure will cause water to move through the soil, h hence th properties the ti off the th soil il will ill change h with ith time ¾Consolidation Theory ¾Foundation Design and Construction ¾Cofferdam C ff d analysis l i ¾L Landslide Mechanisms M m Famous Book From Theory F Th to t Practice in Soil Mechanics KARL VON TERZAGHI (1883 - 1963) Father of Soil Mechanics ¾ Fundamentals of soil mechanics ¾ Consolidation ¾ Shear h strength h off cohesive soils ¾ Stability of earth slopes p Famous Book Fundamentals of Soil Mechanics DONALD WOOD TAYLOR (1900 - 1955) ¾ Soil Classification ¾ Seepage through earth h structures ¾ Shear Strength g Best Teacher in The Harvard University y ARTHUR U CASAGRANDE C S G (1902 - 1981) ¾Application of soil mechanics to design and construction ¾Evaluation and presentation of the results off research in form suitable for readyy use byy the practicing engineer Famous Book Soil Mechanics in Engineering Practice RALPH BRAZELTON PECK (1912 - ) ¾Fundamentals of effective stress ¾Pore pressures in clays ¾Bearing capacity ¾Slope stability Best Teacher in The Imperial College g in The University of London ALEC C WESTLEY S S SKEMPTON O (1914 – 2001) ¾Fundamentals of shear strength ¾Sensitivity of clays ¾Stability bili off naturall slopes Best Teacher and the First Director in The Norwegian Geotechnical Institute LAURITS BJERRUM (1918 – 1973) ¾Concepts of Active and Passive Earth Pressure ¾Concept of Friction ¾Coined C i d the h term “Cohesion” Addressed Add d the h A d Academy off Science (Paris, 1773) presenting a modest "essay on the application of the rules of maxima and minima to certain statics problems relevant to architecture CHARLES AUGUSTIN DE COULOMB (1736 - 1806) Grandfather of Soil Mechanics ¾Active and Passive Earth Pressure theories E Pioneer with a d t determination i ti WILLIAM JOHN MAQUORN RANKINE (1820 - 1872) ¾Concepts in Slope Stability Analysis Geotechnical professor emeritus at the Norwegian Technical University, Trondheim, Norway NILMAR JANBU (1920 - ) PIONEERING CONTRIBUTIONS on ¾ Strength and compressibility of compacted clay soils ¾ Strength and consolidation of natural deposits of soft clay ¾ Cracking of earth dams ¾ Frost action ¾ Flexible and rigid pavement design ¾ Analysis of buried conduits ¾ Pile foundations,, stability y of slopes p and embankments on soft clays ¾ Stress-deformation and liquefaction of sand, and methodologies for investigating failures GERALD A LEONARDS (1921 – 1997) Engineer of the Year (Georgia Society of Professional Engineers), 1973 The Herschel Prize (The Boston Society of Civil Engineers), Engineers) 1976 The ASCE Middlebrooks Award, 1977 The Terzaghi Lecture, 1979 The ASCE Martin Kapp Lecture in New Y York, rk 1985 The Brooks Award, 1990 Elected to The National Academy of Engineering, 1994 The ASCE Middlebrooks Award, 1994 ASCE Forensic Engineer g of the Year Award, 1994 10 The ASCE Terzaghi Award, 1995 Heck of an Engineer g & A Master of Anecdotes GEORGE F F SOWERS (1921 - 1996) ¾ Mechanics of Pile Foundations and Soil-Pile Interaction Analysis ¾ Soil Compaction ¾ Analytical Methods in Pavement Design ¾ Analytical and experimental techniques of earthquake engineering Father of Geotechnical Earthquake Engineering HARRY BOLTON SEED August 19, 1922 — April 23, 1989 ¾ Appropriate methods of calculation for Seismic Design of Foundations ¾ free Torsion Vibrating Pendulum to determine the dynamical properties of soil ¾ Resonance R period i d off th the subsoil b il ¾ Coastal Engineering and Dewatering System y ¾ Highly compressible soils Famous Bookk Foundation ou dat o Engineering g ee g for Difficult Subsoil Conditions LEONARDO ZEEVAERT WIECHERS [...]... isolated locations 5 Most M soils il are very sensitive i i to disturbance di b f from sampling, and thus the behavior measured by a laboratoryy test mayy be unlike that of the in situ soil An Overview Particulate Nature of Soil Nature of Soil Deformation Role of Pore Phase ¾ Chemical Interaction ¾ Physical Interaction ¾ Sharing the Load A brief look at Consolidation Particulate Nature off Soil. .. stabilizing the desert sand? 3 Is the desert sand acceptable for the construction of the wearing surface? 4 What grade and weight of available asphalt make the h most economical, i l satisfactory if wearing i surface? f ? 5 What type and how much compaction should be used? sed? SLOPES AND EXCAVATIONS (a) Natural Slope (c) Excavation for Pipe (b) Excavation for Building (d) Canal UNDERGROUND AND EARTH... type of soil Method of placement Control of actual placement Fillingg Example of an Earth Dam • Two main zones – Clayy core – Rock toe • Gravel filter • Rock facing • Zoned earth dam & homogeneous earth dam Main Factors I What should be the dimensions of the dam to give the most economical, safe structure? 2 What is the minimum safe thickness for the gravel layers? 3 How thick a layer of gravel and... rock facing is necessary to keep any swelling of the clay core to a tolerable amount? 4 What moisture content and compaction technique should be employed to place the gravel and clay materials? 5 What are the strength and permeability characteristics of the constructed dam? 6 How would the strength and permeability of the darn vary with time and depth of water in the reservoir? 7 How much leakage would,... UNDERGROUND AND EARTH RETAINING T STRUCTURES T T • Soil Soil structure interaction • Examples – Pipe Pi shells h ll – Basement walls of the building – Sheet pile wall – Tunnels – Drainage structures Example of Earth retaining structure • Anchored bulkhead • Take care of lateral stresses tr • Stability against shear rupture Main Factors 1 What Wh t type t p off wallll (material (m t ri l and nd cross r section)... under and through the dam? 8 What, Wh if any, special i l restrictions i i on the h operation i off the h reservoir are necessary? Example of a Reclamation Structure • NonNon-availabilityy of good building sites • Harbor and terminal facilities • Hydraulic filling Main Factors I How deep should the sheet pile wall penetrate the foundation soil? 2 How should these piles be braced laterally? 3 What is... • Soil is composed of microscopic or macroscopic discrete particles, which are not strongly bonded together as crystals • Soil particles are relatively free to move with respect to another, p less fluent than the movement of fluid particles • Particulate system pertains to a system of particles, and the science dealing with the stress-strain behavior of soils is referred as Particulate Mechanics Nature... concrete, i.e., dead man man Another way is to use a system of piles ;including some driven at a slope with the vertical;; such a sloping pile is termed a batter pile) vertical 6 What was the distribution of stresses acting on the wall? 7 What type of (drainage system should be installed to prevent a l large diff differential i l water pressure from f d l i on the developing h inside i id off the wall? 8 How... Mechanics Nature of Soil Deformation • Contact forces develop due to applied forces • Contact forces are resolved into normal N and tangential T forces • The usual types of deformation in the vicinity of contact forces ¾ Elastic strain ¾ Plastic strain ¾ Particle P i l crushing hi under d high hi h stress • Contact area enlarges due to the deformations, deformations and thus the center of the particles come... the wall penetrate the foundation soil in order to prevent the wall from kicking out to the left at its base? 3 At A what h height h i h on the h wallll should h ld the h anchor h tie i be b located? l d? 4 How far from the wall should the anchor tie extend? 5 What type of anchoringg system should be employed at the onshore end of the anchor tie? (One way to anchor the wall is to use a large mass of ... surface? What grade and weight of available asphalt make the h most economical, i l satisfactory if wearing i surface? f ? What type and how much compaction should be used? sed? SLOPES AND EXCAVATIONS... movement of fluid particles • Particulate system pertains to a system of particles, and the science dealing with the stress-strain behavior of soils is referred as Particulate Mechanics Nature of Soil. .. Soil Nature of Soil Deformation Role of Pore Phase ¾ Chemical Interaction ¾ Physical Interaction ¾ Sharing the Load A brief look at Consolidation Particulate Nature off Soil • Soil is composed