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Unformatted text preview: Soil Mechanics(CENG-2202) Chapter 2 : Simple Soil Properties - 10 - Department of Civil Engineering, Faculty of Technology Addis Ababa University 2. SIMPLE SOIL PROPETIES 2.1 WEIGHT-VOLUME RELATIONSHIPS It is often required of the geotechnical engineer to collect, classify and investigate soil samples. Be it for design of foundations or in calculations of earthwork volumes, determination of soil type and physical soil parameters are routinely encountered in practice. Soil parameters are determined by relating the constituents of the sample. We have seen that soils are uncemented or weakly-cemented accumulation of mineral particles with void spaces between the particles filled with air and/or water. As a result, soils are three-phase systems consisting of solids, water, and air. The weight-volume interrelationships between these phases are important in understanding the behavior of a given soil sample. The three-phase system of a given soil sample can be represented by the block diagram shown in Figure 2.1. Figure 2.1 Three phases of a soil element The total volume of the soil sample as shown in Figure 2.1 can be expressed as a w s v s V V V V V V + + = + = (2.1) Where V = total volume of soil V s = volume of solids V v = volume of voids V w = volume of water in the voids V a = volume of air in the voids Since the weight of the air in the voids is negligible for practical uses, the total weight of the sample is W = W s + W w (2.2) Air Water Solid W w W s W V a V w V s V v V Soil Mechanics(CENG-2202) Chapter 2 : Simple Soil Properties - 11 - Department of Civil Engineering, Faculty of Technology Addis Ababa University Where W = weight of the sample W s = weight of solids W w = weight of water Based on Eqs. (2.1) and (2.2), many relations can be developed as discussed hereinafter. The volume relationships commonly used for the three phases in a soil element are void ratio , porosity , and degree of saturation . • Void ratio (e) is defined as the ratio of the volume of voids to the volume of solids, i.e....
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This note was uploaded on 11/29/2011 for the course 209 5303 taught by Professor Andre during the Spring '10 term at Iowa Lakes.
- Spring '10