1 Introduction
1.1 Laboratory Tests
1.2 Field Tests
2 Timeliness and Significance of the Current Research Work
3 Experimental Study
3.1 Methodology
3.2 Plate Load Test Set-Up
3.3 Test Load Calculations
Stress (kN/m2) | Diameter of test plate (mm) | Minimum required reaction load (kg) |
---|---|---|
50* | 200 | 157 |
100 | 200 | 315 |
150 | 200 | 472 |
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*Sample calculations
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Stress = 50 kN/m2
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Area of plate = πr 2 = 3.14*(0.01)2 = 0.0314 m2
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Reaction load required (kg) = 50 × 1000 × 0.0314/10 = 157 kg
3.4 Replication of Groundwater Table
3.5 Preparation of Collapsible Soil
3.6 Plate Load Test Details
Test number | Depth of water level below bottom of plate |
---|---|
1 | 2.5B (500 mm) |
2 | 1.5B (300 mm) |
3 | 1.0B (200 mm) |
3.7 Watering Pattern
3.8 Constant Load Application Procedure
4 Test Results and Discussions
4.1 Plate Load Tests–Full Collapsible Soil
4.1.1 Effect of Dripping Water on Settlement of Soil
Depth of groundwater level below foundation | Number of wetting cycles |
---|---|
2.5B | 7 |
1.5B | 5 |
1.0B | 4 |
4.1.2 Effect of Time on Settlement of Soil
Depth of groundwater table | Time (min) |
---|---|
2.5B | 510 |
1.5B | 390 |
1.0B | 330 |
4.1.3 Rate of Collapse
Depth of groundwater table | Settlement of soil before the start of collapse (mm) | Settlement at the end of test (mm) | Time between start of collapse and end of test (min) | Collapse settlement (mm) |
---|---|---|---|---|
2.5B | 9.85 | 15.77 | 30 | 5.92 |
1.5B | 10.74 | 17.00 | 30 | 6.26 |
1.0B | 5.70 | 11.52 | 30 | 5.82 |
4.1.4 Effect of Loading–Reloading on Modeled Groundwater Table
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OMC = 15.5%, MDD = 18.45 kN/m2
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At MDD, \(\gamma_{{d = G\gamma_{{w/\left( {1 + e} \right)}} }}\)
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18.45 = (2.6 × 10)/(1 + e)
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e = 0.4
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$${\text{Now}}\,s = \frac{wG}{e} = \left( {{{15.5} \mathord{\left/ {\vphantom {{15.5} {100}}} \right. \kern-0pt} {100}}} \right) \times 2.6/0.4 = 0.983 = 98.3\%$$
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At 12% moisture content, γ d = 17.8 kN/m3
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$$\gamma_{{d = G\gamma_{{w/\left( {1 + e} \right)}} }}$$
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17.80 = (2.6 × 10)/(1 + e)
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e = 0.46
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\(s = \frac{wG}{e} = \left( {{{12} \mathord{\left/ {\vphantom {{12} {100}}} \right. \kern-0pt} {100}}} \right) \times {{2.6} \mathord{\left/ {\vphantom {{2.6} {0.46}}} \right. \kern-0pt} {0.46}} = 0.68\,\left( {68\% } \right)\)