Lec1_introduction&phase relations.pdf
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This document outlines the internal assessment structure and topics covered in a soil mechanics and foundation engineering course. It discusses the importance of the subject and describes various topics that will be covered, including formation of soils, soil types, phase relations, volume-mass relationships, water content determination methods, specific gravity determination, unit weight determination, and soil classification. Key concepts like three phase diagrams, volume-weight relationships, and index properties are also introduced. The course aims to equip students with knowledge of soil properties and their engineering applications.
![DRY SOILS (TWO PHASE)[OVEN DRIED]
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Lec1_introduction&phase relations.pdf
- 1. CLE1004 SOIL MECHANICS AND FOUNDATION ENGINEERING Dr. Divya Priya Department of Structural and Geotechnical Engineering SCE, VIT, Vellore
- 2. INTERNAL ASSESSMENT 3 Portions Max Mark Weightage Tentative date DA -1 Unit- 1,2 25 15 1st July 2020 Quiz -1 Unit 3,4 15 15 6th July 2020 Midterm Oral Examination Unit 1-5 35 15 9th July 2020 DA -2 Unit – 6,7 25 15 11th July 2020 Total 100 60
- 3. INTRODUCTION 4 What’s the subject is about?
- 4. IMPORTANCE 5
- 5. FORMATION OF SOILS “Soil” in soil engg.- unconsolidated material composed of solid particles produced by disintegration of rocks 6
- 6. FORMATION OF SOILS AND TYPES Soil (based on geological origin) Physical/Mechanical disintegration: retain the mineral component of parent rock causing only reduction of size Involves exfoliation, unloading, erosion, freezing and thawing; Coarse grained Chemical decomposition: also alters the nature and composition of parent rock Involves oxidation, hydration, carbonation and leaching by organic acids and water; Fine grained Organic: extremely compressible 7
- 7. SOIL TYPES 8
- 8. CLASSIFICATION OF TRANSPORTED SOILS Alluvial Soils – carried and deposited in running water Lacustrine – deposited in fresh water of lakes Marine – deposited in ocean or sea Aeolian – deposited by wind Glacial- deposits that have been transported by ice Loess – silt deposit made by wind Bentonite– A chemically weathered volcanic ash Till – deposits directly made by melting of glaciers Colluvial (Talus) – by gravitational forces Peat and Muck (cumulose)- decomposed organic matter 9
- 12. FULLY SATURATED SOILS (TWO PHASE) 13
- 13. DRY SOILS (TWO PHASE)[OVEN DRIED] 14
- 14. PHASE DIAGRAM 15
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- 36. WATER CONTENT DETERMINATION Oven drying method Torsion balance method Pyconometer method Sand bath method and Calcium Carbide/ Rapid moisture meter method 37
- 37. WATER CONTENT DETERMINATION Oven drying method Very accurate, standard, laboratory method IS 2720 (Part 2)-1973 110⁰±5⁰ C for 24 hours For soil containing gypsum 60⁰ to 80⁰ C for more than 24 hours 38
- 38. WATER CONTENT DETERMINATION Torsion balance method Infra-red lamp, torsion balance moisture meter, thermometer IS 2720 (Part 2)-1973 Infra red radiation by 250 W lamp built in the torsion balance with an alternating current of 220-230 V, 50 cycles, single phase. Maximum size of the particle used is less than 2 mm. Time for testing is 15 to 30 min depending upon type of soil and amount of water content 39
- 39. WATER CONTENT DETERMINATION Pyconometer method Pyconometer – 1 litre capacity, fitted with brass conical cap and screw type cover. Cap has 6 mm diameter, rubber and fibre washer provided in the gap between cap and the jar. 40
- 40. WATER CONTENT DETERMINATION Sand bath method Field method, rapid, not accurate. Large open vessel containing sand filled to a depth of 3 cm or more A few pieces of white paper placed on the top of sample. Tray is weighed and sand bath is heated over stove for about 20 to 60 minutes. The white paper turns brown when over heating occurs. 41
- 41. WATER CONTENT DETERMINATION Calcium carbide method When water reacts with calcium carbide, acetylene gas is produced. Moisture meter is used to measure the water content indirectly from the pressure of the acetylene gas formed. Wet soil sample is placed in a sealed container containing calcium carbide. The test requires about 6 gm of soil. The quantity of gas is indicated on the pressure gauge. From the calibrated scale of the pressure gauge, the water content based on total mass is determined. 42
- 42. SPECIFIC GRAVITY DETERMINATION Density bottle method Pyconometer method Measuring flask method Gas jar method Shrinkage limit method 43
- 43. UNIT WEIGHT DETERMINATION Water displacement method Submerged mass density method Core cutter method Sand replacement method Water balloon method Radiation method 44
- 45. INDEX PROPERTIES Index properties: Numerical results obtained based on classification tests Soil grain properties: mineralogical composition, specific gravity, size and shape of grains Soil aggregate properties: dependent on soil mass, influenced by the soil stress history, mode of soil formation and soil structure. Significance in engineering practice. 46