SOIL STUDY IS ESSENTIAL FOR DESIGN OF THE FOUNDATION TYPE IN A GIVEN SOIL

Soils and sites are so variable that it is not practicable to formulate any hard and fast rules, however the chief function of soil studies is to furnish some general principles to supplement and guide the practical experience and free judgement of the Engineer, although it cannot give an exact solution to every practical problem, as such no standard procedures for soil exploration, selection of foundation type in a given soil and its design have been evolved yet. Soil is the naturally occurring loose or soft deposit forming part of the earth's crust, produced as a result of weathering or disintegration or decomposition of the rock formations, or decay of vegetation , intermingled together. The top layer of the ground that supports vegetation is called soil or the top soil and the undisturbed strata lying immediately below the natural top soil is termed sub -soil. Soil contains three components, viz, air, water and solids and the solids are a mixture of mineral matters with particles differing in size, shape and structure and verifying in chemical composition. Organic matter in soil consists of the more or less decomposed remains of plant and animal organisms. It is of the open spongy structure swells or shrinks with increase or decrease of the moisture content and undergoes considerable volume changes under load . It is therefore necessary for testing the bearing capacity of a soil under the conditions of the moisture content and dry density of the test area should be those which are likely to exist when the structure has reached a state of related equilibrium subsequent to the construction of the structure. In area subject to water logging and floods the bearing capacity of a soil should be determined under the wettest conditions that are likely to occur and the soil to be tested should be brought under such a condition by soaking, and the basis of the design should be the strength of the wet soil. Clayey soils are most likely to suffer by water absorption. Soaking can be done by making a small pond of bricks over the area to be tested and keeping it filled with water till the soil attains the expected moisture conditions;required degree of compaction can be obtained by hand tampering in thin layers:-- Er Fateh Chand Guleria, C/O RTI welfare Association registered number HPCD, 3552 , Bilaspur Himachal Pradesh phone number, 9459334377