Civil Engineers Short Notes

🌍 Soil Mechanics — Short Notes (SSC JE/JE Exam) 1. Soil Soil = naturally occurring unconsolidated material consisting of solid particles, water and air. Soil is generally formed by weathering of rocks. Civil Booster 👉 Click here 2. Three-Phase System Solid phase → soil particles Liquid phase → water Gas phase → air 3. Important Soil Types Gravel: 4.75 mm to 80 mm Sand: 0.075 mm to 4.75 mm Silt: 0.002 mm to 0.075 mm Clay: < 0.002 mm 4. Water Content � = weight of dry soil solids 5. Specific Gravity 6. Void Ratio 7. Porosity Relation: 8. Degree of Saturation Fully saturated soil: � 9. Air Content 10. Permeability Ability of soil to allow water to flow through its voids. Sand → high permeability Clay → very low permeability Darcy's law: 11. Atterberg Limits Liquid Limit (LL): boundary between liquid and plastic state. Plastic Limit (PL): boundary between plastic and semi-solid state. Shrinkage Limit (SL): boundary between semi-solid and solid state. Plasticity Index: Civil Booster 👉 Click here 12. Soil Classification — Quick Memory Coarse-grained: Gravel + Sand Fine-grained: Silt + Clay 13. Compaction Compaction = mechanical densification of soil by reducing air voids. Main purpose → increase dry density and improve strength. OMC = Optimum Moisture Content. At OMC, soil attains Maximum Dry Density (MDD) for a given compactive effort. Civil Booster 👉 Click here 14. Consolidation Gradual reduction in soil volume due to expulsion of pore water. Particularly important in saturated clay. It is a time-dependent process. 15. Effective Stress ⭐ � = total stress � = pore water pressure Exam point: Shear strength and many soil properties are primarily governed by effective stress. Civil Booster 👉 Click here

💥What is the difference between perviousness and permeability of soil ✨ Permeability : Permeability is a measure of the ease with which water flows through soils and/or rocks. No soil is completely impervious but some are relatively impervious while others are pervious. Pervious Soil : A soil is said to be pervious soil if it offers minimum resistance to the flow of water through it. 👉 For examples, all clean  coarse grained soils such as gravels, sand and gravel sand mixtures are pervious soil. 👉 The pervious soil have permeability in the range of > 10-2 to  10-5 m/sec. Impervious Soil : 👉 The soil which offers maximum resistance to the flow of water through it is known as impervious soil. 👉 For example, Silts, clay and their mixtures. 👉 The impervious soil have permeability < 10-8 m/sec. #Soil For like this detailed Notes join Special Civil Engineers_49 Contact to join @CivilEngineers_49