Solution of Foundation, concrete, black cotton soil, pile, earthquake, drilling, STAAD pro, ETABS related queries are published here. HOME EARTHQUAKE CONCRETE FOUNDATION DRILLING UNDERPINNING BLACK COTTON SOIL Foundations on Black Cotton Soil The property of volumetric changes with the change of atmospheric conditions makes black cotton soil dangerous to be founded buildings. It swells excessively when wet and shrinks excessively when dry resulting terrible cracks in soil without any warning. It has a great affinity to water. This tendency of soil is on account of the presence of fine clay particles. Cracks are formed due to movement of the ground on account of alternate swelling and shrinkage. The cracks thus formed are sometimes 15 to 20 cm wide and 2.5 to 4 m deep. Safety Precautions The following precautions are generally adopted while building structures on black cotton soil: 1. To limit the load on the soil to 5.5 tonnes/ sqr. m. if water is liable to to find an access to the foundations, the limit of loading should be restricted to 4,900 kg/ sqr. m. 2. To take the foundation to such depths where the cracks cease to extend. The minimum depth of foundation should be at least 1.5 m. 3. To provide reinforced concrete ties or bands all around the main walls of the building. The R.C.C ties or bands which may be 10 cm to 15 cm deep should be placed at plinth level, lintel level and eaves level. In case of flat roof, R.C.C slab it self acts as a tie and as such no extra band needed to be provide near the roof in such cases. 4. If the depth of the black cotton soil at a given site is only 1 to 1.5 m, the entire black cotton soil above the hard bed may be completely removed and the foundation may be laid on the hard bed below. 5. The swelling of soil in direct contact with the foundation material causes maximum damage. Hence it is necessary to prevent the direct contact of black cotton soil with masonry work below ground level. These can be achieved by making wider trenches for foundation and filling spaces on the either side of the foundation masonry with sand or moorum. 6. The bed of foundation trench should be made firm or hard by ramming it well. On the rammed bed a 30 cm layer of good hard moorum should be spread in layers of 15 cm, each layer being well watered and rammed before laying the next layer. On this layer either stone or sand bed should be provided to the desire height to place the foundation concrete bed block upon it. 7. In case of ordinary buildings, the foundation should be taken at least 30 cm deeper than the depth where the crack stop. 8. In important structures raft foundation should be provided so as to float the building on the bed below the depth, quite independent of the surrounding soil. 9. For less important structures like compound walls etc., the foundation should preferably be taken at least 15 cm below the depth at which cracks in soil cease to occur. 10. Construction in black cotton soil should be undertaken during dry season. Foundation Foundation Repair Mat/Raft Foundation Slab-on-Grade Foundation Mud jacking/Slab jacking Pile Foundation Foundation on Expansive soil Underpinning Black cotton soil Earthquake & Foundation Soil Stabilization Concrete Concrete Repair Concrete Pumping Ready-mixed concrete Compaction Pavement Concrete Properties ASTM Concrete ACI Concrete Earthquake Earthquake Design Destruction Tectonics Measuring Earthquake SUGGESTIVE READING Foundation Concrete Earthquake Black Cotton Soil Underpinning Drilling Tweet 33 What is Raft Foundation? Difference between Raft Foundations and Mat Foundation Relation Between Compressive and Tensile Strength of Concrete What is the Difference between Consolidation and Compaction of Foundation Soil? What to Do After Tsunami? What are Filter Criteria for Basic Performance of Geotextiles in Soil Improvement? ALLOWABLE POPULAR POSTS SEARCH THIS BLOG RECENT POST Why is Grouting Applied in Stabilizing Foundation Soil? What are Filter Criteria for Basic Performance of Geotextiles in Soil Improvement? Foundation Problem with Organic Soil Different Types of Pile Hammer for Pile Foundation (Part-2) We're on +173 Like 44 Send Find us on Facebook Earthquake Resistant Construction Like 2,180 people like Earthquake Resistant Construction. Subscribe in a reader 4 Concrete Foundation Foundation Repair Black cotton soil pile foundation Piling Liquefaction Tsunami Corrosion Epoxy Soil Stabilization earthquake map AutoCAD Subduction zone column Asbestos Dam STAAD.Pro. earthquake today mesothelioma underpinning LABELS Foundations on Black Cotton Soil http://civil-engg-world.blogspot.in/2009/06/foundations-on-black-cotton-... 1 of 4 6/24/2013 12:41 AM