Core cutter method
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The document describes the core cutter method for determining the unit weight of fine-grained soils, detailing the equipment and procedure involved. It provides calculations for bulk and dry unit weight using specific weights and geometrical formulas. An example illustrates the application of the method with provided values for soil and cutter weights.
Core cutter method
- 2. For full course visit our website,… This is the excerpt lecture of Soil Mechanics www.machenlink.com
- 3. L. 05 Determination of Unit Weight 1. Core cutter method ❑ Fine grained natural or compacted soils free from aggregates Steel Rammer Cutter Dolley
- 4. L. 05 Determination of Unit Weight 1. Core cutter method ❑ Fine grained natural or compacted soils free from aggregates 900mm approx. 25 mm dia solid mild steel staff Mild steel foot 75 mm ∅ =140 mm Steel Rammer 10 mm 130mm 100 ∅ 106 ∅ Cutter Seamless Steel Tube
- 5. L. 05 Determination of Unit Weight 900mm approx. 25 mm dia solid mild steel staff Mild steel foot 75 mm ∅ =140 mm Steel Rammer 10 mm 130mm 100 ∅ 106 ∅ Cutter Seamless Steel Tube Dolley Rounded off corner 6 mm 25mm 100 ∅ 108 ∅ 115 ∅
- 6. L. 05 Determination of Unit Weight • Cutter is driven into the ground with the help of hammer until dolly extend 1cm above the ground. • Cutter is taken out of the ground and weight of soil retained in it is noted. Procedure : Weight of empty cutter = 𝑤1 Weight of cutter + moist soil = 𝑤2 Volume of core cutter, 𝛾 = 𝑊 𝑉 Bulk unit weight Weight of moist soil, 𝑊 = 𝑤2 − 𝑤1 𝑉 = 0.785 𝐷2 𝐻 Collect a sample of soil from core cutter soil and determine the water content (𝑤) 𝛾 𝑑 = 𝛾 (1 + 𝑤) Dry Unit weight
- 7. A core cutter of 0.1 m internal diameter and 0.128 m height was used to determine the unit weight of soil at a site. The total weight of core cutter and soil was 29.577 kN and empty weight of core cutter was 13.478 kN. A representative sample of soil was kept in a steel cup of weight 0.588 kN for the determination of water content. Weights of cup and soil before and after placing in oven were respectively 1.046 kN and 0.902 kN. Find dry Unit weight of soil and degree of saturation if G = 2.7 . 06. Example 06 (Core Cutter Method)L. 05 Strategy: Solution: 𝛾 = 𝑊 𝑉 Use the following formulae for the determination of Bulk Unit weight and Dry unit weight 𝛾 𝑑 = 𝛾 (1 + 𝑤) Weight of core cutter + soil (𝑤2) = 29.577 kN Weight of core cutter (𝑤1) = 13.478 kN
- 8. Solution: 𝛾 = 𝑊 𝑉 𝛾 𝑑 = 𝛾 (1 + 𝑤) Weight of core cutter + soil (𝑤2) = 29.577 kN Weight of core cutter (𝑤1) = 13.478 kN Example 06 (Core Cutter Method)L. 05 Weight of soil, Volume of core cutter, = 16.09 kN𝑊 = 𝑤2 − 𝑤1 = 29.577 − 13.478 𝑉 = 𝜋 × 𝐷2 𝐻 4 = 0.785 𝐷2 𝐻 = 1.048 × 10−3 𝑚3 𝛾 = 𝑊 𝑉 = 16.09 kN 1.048 × 10−3 𝑚3 = 15.66 𝑘N/𝑚3 Bulk unit weight (𝛾) Dry unit weight (𝛾 𝑑) Weight of steel cup 𝑤1 = 0.588 kN Water content 𝑤
- 9. 𝛾 = 𝑊 𝑉 = 16.09 kN 1.048 × 10−3 𝑚3 = 15.66 𝑘N/𝑚3 Dry unit weight (𝛾 𝑑) Weight of steel cup 𝑤1 = 0.588 kN Water content 𝑤 Example 06 (Core Cutter Method)L. 05 Water Content 𝑤 Weight of water, Weight of solids, Weights of cup and moist soil 𝑤2 = 1.046 kN Weights of cup and dry soil after placing in oven 𝑤3 = 0.902 kN 𝛾 𝑑 = 𝛾 (1 + 𝑤) = 15.66 (1 + 0.45) = 10.8 𝑘N/𝑚3 𝑤 𝑤 = 𝑤3 − 𝑤2 = 0.141 kN 𝑤 𝑑 = 𝑤3 − 𝑤1 = 0.314 kN = 𝑤 𝑤 𝑤 𝑑 × 100% = 0.141 0.314 × 100% = 45% = 0.45