SF4005 Mechanics of Unsaturated Soils Syllabus:
SF4005 Mechanics of Unsaturated Soils Syllabus – Anna University PG Syllabus Regulation 2021
OBJECTIVES:
To impart knowledge in assessing both physical and engineering behaviour of unsaturated soils, measurement and modeling of suction – water content and suction – hydraulic conductivity of unsaturated soils.
UNIT I STATE OF UNSATURATED SOIL
Definition – Interdisciplinary nature of unsaturated soil – soil classification – Nature and practice – stress profiles, stress state variables – material variables – constitutive law – suction potential of soil water
UNIT II PHYSICS OF SOIL WATER SYSTEM
Physical properties of Air and water – partial pressure and relative Humidity Density of moist air – surface Tension – cavitations of water. Solubility of Air in water – Air – water solid interface – vapor pressure lowering – soil water characteristic-curve. Capillary tube model – contacting sphere model. Young Laplace equation – Height of capillary rise – Rate of capillary rise – capillary pore size distribution – theoretical basis – determination – laboratory method.
UNIT III STRESS STATE VARIABLES AND SHEAR STRENGTH
Effective-stress – stress between two spherical particles – Hysteresis in SWCC – stress parameter, stress tensor – stress control by Axis Translation – analytical representation of stress – volume change characteristics. Extended Mohr – Coulomb criterion – shear strength parameters – Interpretation of Direct shear test results and Tri axial test results – unified representation of failure envelope – Influence of suction in earth pressure distribution.
UNIT IV STEADY AND TRANSIENT FLOWS
Driving mechanism – Permeability and Hydraulic conductivity – capillary barriers – steady infiltration and evaporation – Vapor flow – Air diffusion in water. Principles for pore liquid flow – Rate of infiltration, Transient suction and moisture profiles. Principles for Pore Gas flow – Barometric pumping Analysis.
UNIT V MATERIAL VARIABLE MEASUREMENT AND MODELLING
Measurement of total suction – psychrometers – Filter paper measurement of matric suction – High Air Entry disks – Direct measurements – Tensiometers – Air-translation technique – Indirect measurements – Thermal conductivity sensors – measurement of osmotic suction – squeezing technique – soil water characteristic curves and Hydraulic conductivity models.
OUTCOMES:
On completion of the course, the student is expected to be able to
CO1 Explain stress state variables, material variables and constitutive law of unsaturated soil
CO2 Explain the physics of soil-water mechanism, relationship of models.
CO3 Explain and determine the soil-water characteristic curve and the shear strength of unsaturated soil
CO4 Explain the principles of vapour flow, air diffusion, pore liquid flow and rate of infiltration in unsaturated soil.
CO5 Measure the material variables and select the suitable soil models.
REFERENCES:
1. Fredlund, D.G., Rahardjo, H. and Fredlund, M.D., Unsaturated Soil Mechanics in Engineering Practice, John Wiley & Sons, INC, New Jersey, 2012.
2. Ning Lu and William, J. Likes, Unsaturated Soil Mechanics, John Wiley & sons, INC. New Jersey, 2004
3. Ng Charles, W.W., Menzies Bruce, Advanced unsaturated Soil Mechanism and Engineering, Taylor & Francis Group, 2007.
4. Ning Lu, Laureano R. Hoyes and Lakshmi Reddi, Advances in unsaturated soil, seepage and Environmental Geotechnics, ASCE., Geotechnical special publication No.148.
5. Jean- Louis Briaud., Geotechnical Engineering: Unsaturated and Saturated soils, John Wiley & Sons, INC, New Jersey, 2013.