New Soil Investigation

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How to approach the finding out of soil bearing capacity by new soil investigation method...

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New Soil Investigation

  1. 1. SOIL-INVESTIGATION AIM of SOIL INVESTIGATION FIELD TESTS AND LAB TESTS, SOIL PROFILE, ENGINEERING & PHYSICAL CHEM ,PROPERTIES OF SOIL , TYPE OF FOUNDATION, SOIL BEARING CAPACITY PILE CAPACITY Lt Col MC Naorem
  2. 2. Colors and shades of Soil <ul><li>Soil is mother earth, as it supports </li></ul><ul><li>Plant life and animal life </li></ul><ul><li>Soil is derived from disintegrated rock </li></ul><ul><li>It soil absorb and holds moisture </li></ul><ul><li>Soil is Basic civil Engineering material </li></ul><ul><li>Soil is found in all 7 colors of rain bow </li></ul><ul><li>The colors of soil are dull/ dark </li></ul><ul><li>Soil is seen as black and white / color TV </li></ul><ul><li>Some of natural colors are derived from soil </li></ul><ul><li>Soil has vide variation in shape & size </li></ul>
  3. 3. Examples of colored soil <ul><li>White - Called as shadu used for idol making </li></ul><ul><li>contains more lime derived from lime kunker </li></ul><ul><li>Black - Called as black cotton soil and is Expansive in nature but good for vegetation </li></ul><ul><li>Red -Derived from laterite or iron ore </li></ul><ul><li>Orange -Mixture of red and yellow soil </li></ul><ul><li>Yellow - Called as multani soil </li></ul>
  4. 4. Examples of colored soil <ul><li>Green - Organic soil Marine clay </li></ul><ul><li>Blue- Deep blue Marine clay Organic Soil </li></ul><ul><li>Grey- marine clay ,black cotton soil </li></ul><ul><li>Brown- Mixture of different soil forming minerals </li></ul>
  5. 5. SOIL BEARING CAPACITY <ul><li>FIELD TESTS </li></ul><ul><li>SPT, plate load test </li></ul><ul><li>Vane Shear test </li></ul><ul><li>Dynamic cone penetration </li></ul><ul><li>Field-Density (approximation) </li></ul><ul><li>Field observation </li></ul><ul><li>Previous Knowledge </li></ul><ul><li>Field Sample Collection </li></ul><ul><li>LAB TESTS </li></ul><ul><li>Shear tests </li></ul><ul><li>Triaxial test </li></ul><ul><li>Consolidation test </li></ul><ul><li>Settlement Analysis </li></ul>
  6. 6. VARIATION in SIZE and GRADATION OF SOIL I- LL upto 35, I- LL 35 to 50 ,H- LL>50 Clay plasticity-CH- C.I C.L Smaller than 75 micron Clay-C, CH, CI, CL smaller than 75 micron Silt- M- MH, MI, ML Single sized sand Sand poorly graded-SP Having all above sizes in proportion Sand well graded-SW 425 to 75 micron Fine sand-S 2.0 to 425 micron Medium sand-S 4.75 to 2.0 mm Coarse Sand -S Coarse 80 to 20mm and Fine 20 to 4.75mm Gravel-G -GW, GP 300mm to 80mm / Boulders/ Cobbles
  7. 7. General Soil Profile ROCK   BOULDERS   COARES SAND   CLAY   FINE SAND   SILT   FILLEDUP SOIL   ORGANIC SOIL  
  8. 8. SOIL BEARING CAPACITY <ul><li>Essential conditions for a foundation: </li></ul><ul><ul><li>It must have some specified safety against ultimate failure </li></ul></ul><ul><ul><li>The settlements under working loads should not exceed the allowable limits for the super-structure </li></ul></ul><ul><li>Methods of determining SBC </li></ul><ul><ul><li>Through local knowledge and experience on construction </li></ul></ul><ul><ul><li>Soil sampling, examination and classification </li></ul></ul>
  9. 9. SOIL BEARING CAPACITY <ul><li>Methods of determining SBC (contd..) </li></ul><ul><ul><li>Field tests for direct determination of Bearing Capacity </li></ul></ul><ul><ul><ul><li>Plate load test on the soil </li></ul></ul></ul><ul><ul><ul><li>Standard Penetration Test or Vane Test (torsion measured at top indicates shear strength of soils) </li></ul></ul></ul><ul><ul><ul><li>Soil Resistance Test (pit dug out, known wt dropped from known height, average indentation used to determine SBC) </li></ul></ul></ul><ul><ul><li>Lab tests based on engineering properties (shear/vane/unconfined compr etc.) </li></ul></ul>
  10. 10. PROBLEMS IN BLACK COTTON SOIL <ul><li>Soil grains oriented in the form of platelets or sheets </li></ul><ul><li>Ingress of moisture between these sheets causes increase in volume causing swelling </li></ul><ul><li>During summer season, moisture moves out of the soil causing </li></ul><ul><ul><li>shrinkage cracks (almost 10 to 15cm wide on the ground and up to 2 m in depth) </li></ul></ul><ul><ul><li>loss of support beneath the footings, resulting in high settlements </li></ul></ul><ul><li>Some expansive and shrinkable soils stick to the footing base and pull the footing down when they shrink causing horizontal cracks in the walls </li></ul>
  11. 11. <ul><li>Purpose: </li></ul><ul><ul><li>To determine the nature, thickness and variation of soil strata in the region </li></ul></ul><ul><ul><li>To procure soil samples for assessing the physical properties, which will help in design and mode of construction of proposed foundation </li></ul></ul><ul><ul><li>To identify the seasonal variations in ground water table and their possible effects on the soil strata met </li></ul></ul><ul><ul><li>To determine the depth of underlying rock bed, when necessary </li></ul></ul>SITE INVESTIGATION
  12. 12. <ul><li>Methods of Soil Exploration </li></ul><ul><ul><li>Open test pits or Trial pits </li></ul></ul><ul><ul><li>Sub-surface soundings </li></ul></ul><ul><ul><li>Borings (Tube, Auger, etc.) </li></ul></ul><ul><ul><li>Geophysical methods – seismic and electrical resistivity methods </li></ul></ul><ul><ul><li>Vane test for shear strength </li></ul></ul>SITE INVESTIGATION (contd…)
  13. 13. <ul><li>Methods of Soil Exploration – Open pits or Test pits </li></ul><ul><ul><li>Most common and simplest method </li></ul></ul><ul><ul><li>Used for small depths (up to 3m) </li></ul></ul><ul><ul><li>(at greater depths, ground water causes problems in case of open pit exploration) </li></ul></ul><ul><ul><li>Provides reliable information about the sub-surface conditions </li></ul></ul>SITE INVESTIGATION (contd…)
  14. 14. CONTENTS <ul><li>Determination of Soil Bearing Capacity </li></ul><ul><li>Improvement of Soil Bearing Capacity </li></ul><ul><li>Types of loads </li></ul><ul><li>Types of foundations </li></ul><ul><li>Basis of selection of types of foundations and obtaining depth of foundation </li></ul><ul><li>Failure of foundations </li></ul><ul><li>Problems in black cotton soil </li></ul><ul><li>Well foundation and coffer dam </li></ul><ul><li>Design criteria for shallow foundations </li></ul><ul><li>Grouping of piles </li></ul>

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