PhaseRelationships_Lecture 1(2)

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J  Soil Mechanics : a branch of Geotechnical Engineering that concerns with the mechanics, properties and behaviour of soils (ncemented, or weakly cemented, deposit of minerals and rock particles)  Rock Mechanics : a branch of Geotechnical Engineering that concerns with the mechanics, properties and behaviour of rocks (cemented agglomeration of minerals) Civil Engineering Geotechnical Engineering Soil Mechanics Rock Mechanics geo − earth technical − technology (civil engineering technology).  Geotechnical Engineering uses principles of Soil Mechanics, Rock Mechanics and Geology in the design

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Slopes and Earth Retaining Structures http://cdn.cenews.com/2014/12/CS_Materials-MSEWalls/01-01-010BPStrohman-Figure1-Components-MSE-Wall.jpg

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Supported Excavations https://www.google.com/search?rlz=1C1GCEB_enAU958AU958&q=supported+excavations&tbm=isch&sa=X&ved=2ahUKEwiK9- qO756AAxXTEogKHRgQBvcQ0pQJegQIDRAB&biw=1920&bih=969&dpr=1#imgrc=olmBhG5pSrEGBM

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J National Freeway 3 - Taiwan https://blogs.agu.org/landslideblog/2010/04/26/the-mechanism-of-the-highway-3-landslide-in-taiwan/

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Timetable  Lecture : Monday 8-10 am - (402:220LT)  Tutoria l: Friday 4-6pm - (410:201CT)  Laboratories (Building 206:124) • Three different sessions, you MUST attend all . • Tuesdays and Wednesday see Blackboard for lab times.

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Assessments – GEOT2000  20% - Assignments: (Semester week 12) - lab work 5%, Design Report final submission 15%  30% - Mid-Semester Test (Semester week 9, day/time TBC) –  50% - Final Exam (Examination period)  To pass the unit you must: - Achieve at least 45% in the final exam. - Achieve a grade/mark greater than or equal to 50%.

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Assessments – GEOT5000  25% - Assignments : (Semester week 12) - lab work 5%, Design Report(s) final submission 20%  25% - Mid-Semester Test (Semester week 9, day/time TBC) –  50% - Final Exam (Examination period)  To pass the unit you must: - Achieve at least 45% in the final exam. - Achieve a grade/mark greater than or equal to 50%.

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J GEOT2000 / GEOT5000 Soil Composition and Classification

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J 127 kN/m 3 117 kN/m 3 4000°K 3000°K 2000°K 27 kN/m 3 44 kN/m 3 - Fe and Ni (8 g/cm 3 ) http://www.universetoday.com/wp-content/uploads/2010/03/2000px-Earth-cutaway-schematic-english.svg_.png “lith” = rock “asthenos” = weak Components of the Earth

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Rocks Forming the Earth’s Crust  There are three broad groups of rocks: - Igneous rocks - Sedimentary rocks - Metamorphic rocks Rock : is a cemented agglomeration of minerals.

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Igneous Rocks Igneous rocks are formed from the magma (i.e. molten rocks of the Earth’s mantle) when it flows to the Earth’s surface and cools to produce either extrusive or intrusive Igneous rocks.

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Sedimentary Rocks  Sedimentary rocks are produced from sediments that are derived by weathering of pre-existing rocks, and transported as solid particles to their site of deposition. By time, sediments are buried, compacted and cemented in a process called lithification to form the sedimentary rocks. Weathering (Mechanical – Chemical) ) Gravel River Plain Transportation Lithification Quartz Feldspar Pore space A Quartz Feldspar Pore space A After deposition Overburden B Overburden B Compaction Cement C Cement C Cementation

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Metamorphic Rocks - Metamorphism is the process of transforming a certain type of rocks into a new type due to heat and/or pressure. - The characteristics of a metamorphic rock depend on the characteristics of its original rock (parent rock) and the type, intensity and duration of the metamorphism process.

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Prider Field Trip - http://www.gsa.org.au/resources/guidebook10.pdf

Soil Composition • Soil : is an uncemented, or weakly cemented, deposit of minerals, organic and rock particles resulting from the weathering of rocks. • The engineering properties of soil rely on the interaction between these particles. unsaturated saturated Voids filled with water Voids filled with air Voids Solids

The Particulate Nature of Soil https://premierequestrian.com/three-things-to-understand-about-sand/ Course grained soils Fine grained soils Particle size (mm) clay cobbles silt sand gravel fine medium coarse fine medium coarse fine medium coarse 0.002 0.075 2.36 63.0 0.006 0.02 0.2 0.6 6.0 20.0

Curtin University is a trademark of Curtin University of Technology CRICOS Provider Code 00301J Plummer et al (2013)  Clay forms from minerals evolved from chemical weathering of rock- forming minerals  Gravel, Sand and Silt are made up from rock-forming minerals (e.g. Quartz)

The Soil Phase Diagram

Phase Diagram & Relationships W a , W w , W s = weights of air, water and solids V a , V w , V s = volumes of air, water and solids W t , V t = total weight of soil, total volume of soil V v = volume of voids Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t unsaturated saturated Voids filled with water Voids filled with air

Fully saturated Evaporation zone = fully dry partially saturated or unsaturated WT A S A S W W S G.S Capillary zone

Basic Definitions Moisture Content: 100 (%) × = s w c W W m m c (0-100%) can be ≥100% for saturated clays and organic material Degree of Saturation: 100 (%) × = v w V V S S = 0% for dry soils = 100% for fully saturated soils = (0 - 100%) for partially saturated soils Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t water in soil

Basic Definitions (cont.) Void Ratio: s v V V e = Air Voids: 100 (%) × = t a v V V A • expressed in decimal • void ratio of fine grained soils are generally higher than those of coarse grained soil. e = 0.3 – 1.5 for most soils > 1.5 for organic soils = 4 for swelling soils Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t Voids in soil Porosity: 100 (%) × = t v V V n • expressed in percentage • the range of porosity is 0 < porosity < 100%.

Basic Definitions (cont.) Dry Unit Weight: t s d V W = γ Bulk (total) Unit Weight: Also sometimes seen as γ b t t t V W = γ Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t c t d m + = 1 γ γ How? Saturated Unit Weight: t t sat V W = γ Water Solids W w W s W t V w V v V s V t = w γ 81 . 9 ) ( ) ( × = ton mass kN Weight (unit weight of water) = 9.81 kN/m 3 Density or unit weight of soil Air Solids W s V w V v V s V t = W a = 0 at moisture content corresponding to S = 1

Specific Gravity • Known volume of water • Known mass of dry soil = M s • Rise in water level tells us volume of the solids V s 𝜌𝜌 𝑆𝑆 = 𝑀𝑀 𝑠𝑠 𝑉𝑉 𝑠𝑠 V s GS = γ 𝑠𝑠 γ 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 = 𝜌𝜌 𝑠𝑠 𝜌𝜌 𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤𝑤 w s s w s s V W G γ = γ γ = = 2.6 – 2.8 for most soils = as low as 2 for organic soils = as high as 3.8 for mine tailings

e G w s d + = 1 γ γ  How is this derived??

Parameter Equation Typical Range Density 𝜌𝜌 = 𝑀𝑀 𝑉𝑉 𝑇𝑇 1.4 - 2.2 g/cm 3 Dry density 𝜌𝜌 𝑑𝑑 = 𝑀𝑀 𝑠𝑠 𝑉𝑉 𝑇𝑇 1.2 - 2.0 g/cm 3 Unit weight 𝛾𝛾 = 𝑊𝑊 𝑉𝑉 𝑇𝑇 14 - 22 kN/m 3 Dry unit weight 𝛾𝛾 𝑑𝑑 = 𝑊𝑊 𝑠𝑠 𝑉𝑉 𝑇𝑇 12 - 20 kN/m 3 Water (moisture) content 𝑤𝑤 = 𝑀𝑀 𝑤𝑤 𝑀𝑀 𝑠𝑠 × 100% 10 – 50 % Void ratio 𝑒𝑒 = 𝑉𝑉 𝑣𝑣 𝑉𝑉 𝑠𝑠 0.4 – 1.5 Porosity 𝑛𝑛 = 𝑉𝑉 𝑣𝑣 𝑉𝑉 𝑇𝑇 25 - 60 % Degree of Saturation 𝑆𝑆 = 𝑉𝑉 𝑤𝑤 𝑉𝑉 𝑣𝑣 10 - 1000 % Specific gravity 𝐺𝐺 𝑆𝑆 = 𝜌𝜌 𝑠𝑠 𝜌𝜌 𝑤𝑤 = 𝑊𝑊 𝑠𝑠 𝛾𝛾 𝑤𝑤 𝑉𝑉 𝑠𝑠 2.65 – 2.8

Three Phase Soil Models Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t =1 UNIT TOTAL VOLUME UNIT SOLID VOLUME Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w e V s = 1 Specific volume v = 1 + e V t = V s + V v s v V V e = Assume V s = 1 V t = 1 + e V t = V s + e V s

To obtain all phase relations, it is only necessary to measure (in the laboratory) the moisture content, bulk unit weight (or dry unit weight) and specific gravity. Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t Moisture Content: 100 (%) × = s w c W W m ? Bulk Unit Weight: t t t V W = γ Dry Unit Weight: c t t s d m γ or V W γ + = 1 ? Specific Gravity: w s s w s s V W G γ = γ γ = ? V sand at known density with known volume (i.e. V cone ) V hole = V t = V sand - V cone

 Before solving any phase relations problem, sketch a phase diagram first and then fill out the missing volumes and weights (or masses) of each phase, then solve your problem  If no information is given about the volume and mass of a soil, it is acceptable to assume a unit total volume (V t = 1 m 3 ) or unit solid volume (V s = 1 m 3 ) .  Try not to memorise the phase relations but understand them

Worked Example (1) A cylindrical sample of moist (wet) clay has a diameter of 38 mm, height of 76 mm and mass of 174.2 g. The sample was kept in the oven at 105 o C for about 24 hours and the clay mass was reduced to 148.4 g. The specific gravity of this clay is 2.7. Determine the bulk unit weight, dry unit weight, water content, degree of saturation and void ratio. Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t t t t V W = γ c t t s d m γ or V W γ + = 1 100 (%) × = s w c W W m 100 (%) × = v w V V S s v V V e =

A sample has a volume of 150 mL and loses 33g when oven dried from a bulk unit weight of 20.6 kN/m 3 . Assume any necessary information. Gs = 2.7. • What is the void ratio? ( Answer 0.44 ) Air Water Solids Weight (or mass) Volume W a = 0 W w W s W t V a V w V v V s V t Practice: