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Published byCarl Huxford Modified over 9 years ago
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Wuttichai Prachantrikal Master Candidate Geotechnical Engineering Civil and Environmental Engineering University of Missouri - Columbia Hydraulic Conductivity of MoDOT Type 5 Base Rock Geotechnical Engineering
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Background Objective Scope of Work Methodology Results to Date Ongoing Activities Geotechnical Engineering
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Type 5 Base Rock is a material containing a wide particle size distribution of gravel, sand, and fines. Used for the base of roadways. Geotechnical Engineering
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Type 5 Base on Roadway ~4 inches Geotechnical Engineering Hydraulic conductivity of the base for good drainage practice should be about 1 cm/s
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“The conventional undrained pavements which fail prematurely from water damage are extremely uneconomical in the long-run when compared with well drained pavement” Life undrain pavement ~ 15-30 yrs Life well drain pavement ~ 45-90 yrs (H.R.Cedergren, 1967) Geotechnical Engineering
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Rigid Surface Base Subbase Infiltration No drainage
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Geotechnical Engineering
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Objective: Determine the hydraulic conductivity of MoDOT Type 5 base rock and the impact of fines content on the hydraulic conductivity Geotechnical Engineering
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Scope of work: 1.For a single Type 5 source: a. grain size distribution b. compaction curve c. hydraulic conductivity ( of the compaction curve) 2. Effects of fines content: a. compaction curve b. hydraulic conductivity c. long term flow Geotechnical Engineering
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Methodology: 1.Sieving 2.Compaction 3.Permeability Testing Geotechnical Engineering
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Sieving: Geotechnical Engineering
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Type 5 Grain Size Distribution MoDOT Spec. Percent Fine Range from 0 to 15 percent Sieving: Geotechnical Engineering
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Aggregate Used in Test Boone Quarries, Columbia, Missouri Fines (Passing #200) – Sieved out Re-Blend the Aggregate to Percent Fine @ 0, 3, 6, 9, 12, 15% Geotechnical Engineering
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Compaction ASTM D698 Standard Proctor 6” Diameter 4.5” Height Mold 56 Blows per lift – 3 lifts Geotechnical Engineering
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Compaction Geotechnical Engineering max w opt
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Permeability Testing Rigid-wall, Double-Ring: Geotechnical Engineering
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Constraints: 1.4” diameter mold 2.Side wall leakage 3.1/8” diameter port 4.S r < 1 Rigid-wall, Double-Ring:
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6-inch constant head test: Geotechnical Engineering 6” mold
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6-inch constant head test: Advantages: 1.6” diameter 2.Saturated S r =1 3.Large Flow Capacity 6” mold Geotechnical Engineering
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inflow overflow Type5 outflow 25.25” 4” 5” 4-inch long-term flow test: GT Geotechnical Engineering
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Result to Date: 1. Grain Size Dist. Boone County Quarries Geotechnical Engineering Unmodified
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Grain Size Dist. Boone County Quarries Geotechnical Engineering 0% Fine
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2. Compaction Curve Geotechnical Engineering
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Compaction Curve (cont’) Geotechnical Engineering
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3. Hydraulic Conductivity – 4.5% Fine Rigid Wall Double Ring Geotechnical Engineering
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k w/ soil (max) = 2 x10 -4 cm/s k inner ring = 1.1x10 -2 cm/s (k system ) k outer ring = 9.3x10 -3 cm/s (k system ) k system > k w/soil OK Geotechnical Engineering Rigid Wall Double Ring (Calibration)
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Hydraulic Conductivity – 3%Fine Geotechnical Engineering
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Hydraulic Conductivity of Type 5 Base Geotechnical Engineering
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Hazen (1911) k(cm/s) = D 10 2 Moulton (1979) k(ft/d) = [ 6.214x10 5 D 10 1.478 n 6.654 ]/P 200 0.597 D 10 = particle size in mm at 10% passing n = porosity P 200 = percent passing No.200 Geotechnical Engineering
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Predicted k vs. Measured k Geotechnical Engineering
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Summary of Results Geotechnical Engineering
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Long term flow Geotechnical Engineering
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Observation to Date Geotechnical Engineering Percent fines in unmodified Type 5 base ~ 4-5% 4 in Rigid Wall Double Ring give much lower k than 6 in permeameter Max Dry Unit weight increase with fine content k decrease with fines content k measure is close to k hazen at both 0, 3% but higher at 6% fines k measure is close to k moulton at 6% but lower at 3% fines Flow rate decrease with time in Long term flow and get to the steady state at about 50 hrs
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Geotechnical Engineering On Going Activities Continue on 6,9,12,15 Percent Fine Long term flow (Awilda) Field k
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Question?
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Grain Size Dist. Boone County Quarries Geotechnical Engineering 3% Fine
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Grain Size Dist. Boone County Quarries Geotechnical Engineering 6% Fine
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Geotechnical Engineering Compaction Curve (cont’)
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Geotechnical Engineering
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Hydraulic Conductivity - 0% Fine Geotechnical Engineering
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Hydraulic Conductivity – 6%Fine Geotechnical Engineering
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