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STABILIZATION OF BLACK COTTON SOILs.pptx
- 1. STABILIZATION OF BLACK COTTON SOIL Department of Civil Engineering National Institute of Technology Kurukshetra Submitted to: Dr .Ashwani Jain Submitted by: Yogesh
- 2. CONTENTS INTRODUCTION OBJECTIVES PROPERTIES OF BLACK COTTON SOIL NEED FOR STABILIZATION METHODS OF STABILIZATION CASE STUDY AND EXAMPLES ADVANTAGES AND LIMITATIONS CHALLENGES AND FUTURE TRENDS WHY IS IT RISKY TO BUILD FOUNDATIONS IN BLACK COTTON SOIL? CONCLUSION REFERENCES
- 3. INTRODUCTION • Land utilization increase due to population and industries, boosting demand. • Constructors build on soft ground, expansive soils due to demand. • Soft soils have low bearing capacity, settlement issues. • Need for solutions led to various techniques, including soil stabilization. • Soil Stabilization: • Enhances soil's engineering properties. • Allows versatile use in engineering projects. • Ensures satisfactory performance.
- 5. Properties of Black Cotton Soil: Expansive soils are clay of high plasticity. They contain essentially the clay mineral montmorillonite. The soils have high shrinkage and swelling characteristics. The shearing strength of the soils is extremely low. The soils are highly compressible And have very low bearing capacity.
- 6. Properties of Black Cotton Soil: The tendency of expansive soil to increase in volume due to infiltration of water is resisted by the structure resting on the soil and as a consequence, vertical swelling pressure is exerted on the structure. Swelling pressure develop if the soil is not allow to swell freely. If the swelling pressure exerted by soil is not controlled, it may cause uplift and distress in structure. • Maintenance costs, time delays.
- 7. Need for Stabilization: Enhancing stability. Stabilization techniques act as a safeguard, transforming the soil into a stable foundation capable of withstanding the stresses imposed by structures. • Mitigating settlement aim to reduce this settlement, ensuring that structures remain level and free from tilting, cracking, • Improved load-bearing capacity. opens up opportunities for constructing larger and more substantial structures. • Demand for infrastructure, scarcity of suitable sites. utilizing available land efficiently • Utilizing challenging soils, like black cotton soil.
- 8. PURPOSE OF SOIL STABILIZATION
- 9. (a) Typical cracks in BC soil during dry season, (b) typical crack scene on roads around Ambo, and (c) a serious damage on a house constructed on BC soil in Ambo, Ethiopia.
- 10. Methods of Stabilization: 1. Mechanical Methods: 1. Compaction: Increased density, reduced air voids.
- 11. Methods of Stabilization: 2.Preloading: Temporary loads accelerate consolidation. 3. Vibro-Compaction: Densification through vibrations
- 12. Methods of Stabilization: 2. Chemical Methods: 1. Lime Stabilization: Chemical reaction, reduced plasticity.
- 13. Methods of Stabilization: 2.Cement Stabilization: Cement-water-soil matrix, improved strength. 3.Fly Ash Stabilization: Pozzolanic materials, reduced permeability.
- 14. Methods of Stabilization: 3.Geosynthetic Methods: 1. Geotextiles and Geogrids: Reinforce soil structure, enhance stability.
- 15. Case Studies and Examples: 1. Indira Gandhi International Airport Terminal 3 Expansion 2. Thane Metro Station, Mumbai: 3. Highway Construction in Texas, USA:
- 16. 1.Indira Gandhi International Airport Terminal 3 Expansion Challenge: The expansive black cotton soil beneath the new terminal's site threatened its structural integrity due to its shrink-swell behaviour. Stabilization Method: Lime stabilization was employed to modify the soil's properties and enhance its engineering characteristics.
- 17. 1.Indira Gandhi International Airport Terminal 3 Expansion Outcomes: - Increased Stability: Lime stabilization effectively mitigated the soil's shrink-swell behaviour, reducing the risk of cracks and differential settlement. - Enhanced Load-Bearing Capacity: The soil's improved properties allowed it to support the considerable load of the terminal and its infrastructure. - Structural Success: The new terminal stands today on a stable foundation, ensuring its safety and long-term durability.
- 18. 2. Thane Metro Station, Mumbai, India: * Unstable black cotton soil posed a significant challenge in constructing the foundation for the Thane Metro Station. Stabilization Method: A combination of chemical stabilization methods, including lime and cement, was employed to strengthen the soil. 2
- 19. 2. Thane Metro Station, Mumbai, India: Outcomes: - Reduced Settlement: The chemical stabilization methods significantly reduced soil settlement, ensuring the stability of the foundation. - Enhanced Engineering Properties: The treated soil exhibited improved cohesion, shear strength, and load-bearing capacity. - Structural Integrity: The Metro station's foundation remained stable, safeguarding the safety of passengers and the longevity of the structure
- 20. 3. Highway Construction in Texas, USA: Challenge: Expansive black cotton clay soils along the highway route posed construction difficulties. Stabilization Method: Lime treatment was used to modify the soil's properties and enhance its stability. Outcomes: - Improved Load-Bearing Capacity: Lime stabilization significantly increased the soil's load-bearing capacity, enabling the construction of a stable highway foundation. - Reduced Shrink-Swell Behaviour: The soil's susceptibility to shrink-swell cycles were minimized, leading to decreased cracking and surface disruptions. - Long-Term Durability: The highway stands on a foundation that resists the challenges of black cotton soil, ensuring its performance over time.
- 21. Advantages and Limitations: • Advantages: Improved load-bearing capacity, reduced shrink-swell susceptibility, enhanced engineering properties. • Limitations: Environmental concerns with chemical stabilization. Such as CO2 emission (cement stabilization) can increase brittleness and cracking potential of soil Sulphate attack (lime stabilization)
- 22. Challenges and Future Trends: • Challenges: Soil variability, site-specific factors. • Ongoing research: Sustainable stabilization, material science advancements.
- 23. Why is it Risky to Build Foundations in Black Cotton Soil? Expansive behavior leads to instability, cracks, and settlement. Mass Excavation vs. floating foundations.
- 24. Mass Excavation When building on land with black cotton soil, the entire top soil is always removed through excavation using building machinery. Once the soil has been excavated, you can start construction using the normal strip foundation that is common for residential houses. The additional costs that the homebuilder incurs here include the costs of hiring an excavator, transportation costs of the excavated soil, and backfill materials.
- 25. Using floating foundations Generally, if the black cotton soil is more than 1.5m in depth and the homebuilder has no intention of creating a basement, it becomes uneconomical to excavate the whole of it. This requires a suspended type of foundation whereby columns are dug till solid rock or firm ground and protrude slightly above the ground level.
- 26. Conclusion: • Black cotton soil's importance in modern construction. • Stabilization techniques as solutions to challenges. • Sustainable and eco-friendly trends. • Potential of black cotton soil for infrastructure growth.
- 28. THANKS