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69DAQ Data CollectionWhile performing loading on the pier or groups of piers, the top of the pier displacement aswell as the axial load were recorded by the IOTech DAQ computer software. The tell-taleplate displacement data was collected manually. A sample of the data output file produced byDAQ software is depicted in Figure 39.800800700700600600Load, kgLoad, kg500500400400300300200200Peak100100End030 60 90 120 150 180 210 240 270 3000 30 60 90 120 150 180 210 240 270 3001212(a)1010Displacement, mmDisplacement, mm88664422000 30 60 90 120 150 180 210 240 270 3000 30 60 90 120 150 180 210 240 270 300Time, minTime, min(b)Figure 39: DAQ sample (a) displacement output raw data and (b) load output raw data
70The horizontal axis on both charts represents the time scale and is expressed in units ofseconds. Therefore, from the data charts it can be observed that the loading was performed inincremental sequence. As the time-load chart shows, the duration of the load maintained ateach load increment was limited to approximately 15 minutes. The reason behind applyingthe load for a certain time of duration is for the deflection measurement to reach themaximum magnitude while undergoing creep under load.While the load would peak out at the initial phase of each load increment, the load wouldcontinue dropping in exponential fashion until an asymptote is reached. Therefore, a certainload was applied to the pier until the change in rate of deflection was less than 0.25 mm perhour or 0.0635 mm per each 15 minutes.<strong>Maxim</strong>um load applied to the aggregate piers was 150 percent of the maximum design stress(assumed at 70MPa), however the controlling parameter was the amount of settlement beingproduced. In some cases, the maximum stress imposed on the pier exceeded 150 percent toachieve the total 12 mm amount of displacement. For the purpose of generating stressdisplacementplots the average value of peak and end loads was used for each interval.Consequently, the incremental loading levels were different for different groups of piers,while the majority of aggregate piers were loaded at 9, 17, 33, 50, 67, 83, 100, 117, 133, 150percent of maximum design stress (assumed at 70MPa). It is also important to note that theload on the aggregate piers at 117 percent level required special treatment, where longer loadincrement of 60 minutes was imposed. Therefore, the load was adjusted to the desired 117percent for total number of four times. The unloading phase was also performed where loadwas reduced to the design stress levels of 100, 66, 33 percent of the design stress.Group and Individual Pier LayoutThe second stage of this research study, the individual piers of various length andcomposition were built. A total number of 20 piers were evenly spaced within the available
Page 1:
Engineering behavior of small-scale
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viLIST OF FIGURESFigure 1: Concept
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viiiFigure 62: Stress-settlement te
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xLIST OF TABLESTable 1: Stiffness m
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xiiLIST OF EQUATIONSEquation 1: Ult
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xivSymbol Description Unitsγ dry l
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1CHAPTER 1: INTRODUCTIONIndustry Pr
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7MAKECAVITYPLACESTONE ATBOTTOM OFCA
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9Normal Stress, kPaShear Stress. kP
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11pier element for a maximum of 25
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13savings provided by the system (A
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15The bearing capacity accredited t
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17Equation 12: Load resistance prov
Page 34 and 35: 19Soil conditions at the site were
Page 36 and 37: Settlement (mm)Settlement (mm)10202
Page 38 and 39: 23Site soil conditions were describ
Page 40 and 41: 25Article#ReferenceTable 2: Case st
Page 42 and 43: 27Article#7ReferenceHughes andWithe
Page 44 and 45: 29replaced with method of freezing
Page 46 and 47: UNREINFORCED COLUMNNO COLUMNREINFOR
Page 48 and 49: 33The load carrying capacity was fo
Page 50 and 51: 35Case 5 - Bachus and Barksdale, 19
Page 52 and 53: 37full depth of the consolidated la
Page 54 and 55: 39CHAPTER 3: RESEARCH METHODOLOGYCr
Page 56 and 57: 41itself was designed to be support
Page 58 and 59: 43While it is obvious that the chan
Page 60 and 61: 45To perform all the required testi
Page 62 and 63: 47In the areas where access was lim
Page 64 and 65: 49CBR from DCPThe California Bearin
Page 66 and 67: 305 mm610 mm305 mm610 mm305 mm610 m
Page 68 and 69: 53The process of using the Shelby t
Page 70 and 71: 15881556144815591597154915271586158
Page 72 and 73: 57Table 14: Top and bottom UC loess
Page 74 and 75: 59Data Collection and SensorsHaving
Page 76 and 77: 61Micro Epsilon displacement transd
Page 78 and 79: 63plate down the cavity through man
Page 80 and 81: 65Beveled Tamper HeadsThe other asp
Page 82 and 83: 67All, aggregate, cementitious and
Page 86 and 87: 71space in the test bed (See Figure
Page 88 and 89: 73(a)(b)(c)Figure 42: Test bed grou
Page 90 and 91: 75CHAPTER 4: MATERIALSThe materials
Page 92 and 93: 7710080LL = 31PI = 7Pass. #200 = 98
Page 94 and 95: 79the second stage of testing. Mois
Page 96 and 97: 81Knowing the gradation characteris
Page 98 and 99: 83More importantly, the performed d
Page 100 and 101: 85Figure 49: Cement type I compound
Page 102 and 103: 87As the expansive and contractive
Page 104 and 105: 89Figure 55: 19 mm polypropylene fi
Page 106 and 107: 91CHAPTER 5: TEST RESULTS AND ANALY
Page 108 and 109: 93Applied stress at top of pier (kP
Page 110 and 111: 95Figure 60: Stress-settlement test
Page 116 and 117: 101Figure 66: Stress-settlement tes
Page 120 and 121: 105Settlement (mm)024681012Applied
Page 122 and 123: 107to the maximum displacement of 1
Page 124 and 125: 109The failure mechanism of other p
Page 126 and 127: 1113000Measured Bearing Capacity (k
Page 128 and 129: 113Applied stress at bottom of the
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119Settlement (mm)0246810Applied st
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121The group efficiency results wer
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123Pier typeAggregate PierUnit Cell
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125Figure 82: Stress-settlement tes
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Page 144 and 145:
Page 146 and 147:
131Applied stress at bottom of the
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133Table 33: Group efficiency compa
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135Having a limited amount of exper
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137Stiffness, kPa/mm600500400300200
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139In case with the piers consistin
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141Table 36: Stiffness ratio calcul
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143Some of the loess composition pi
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145Pier typeAggregatePierSingle Pie
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147Another observation was made, wh
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149As previously outlined, the stif
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151pier group efficiency values wer
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Stiffness Ratio1538Figure 91: Stiff
Page 170 and 171:
155CHAPTER 7: SUMMARY AND CONCLUSIO
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157MaterialsLoess-CementVery intrig
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159Groups of PiersGroup of Aggregat
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161CHAPTER 8: FUTURE RESEARCHThe fu
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163Black, J.A., Sivakumar, V., Madh
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165Hanlong, L., An, D., and Yang, S
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167Randrup T.B., and Lichter, J.M.
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169Yeh, Y.K., and Mo, Y.L. (2005).
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171Group EfficiencyAggregate Pier G
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173Aggregate Pier305mm Wedge HeadDC
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175Loess + Fibers305mm Single PierD
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177Sand305mm Single PierDCPI, mm/bl
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179Aggregate Pier305mm Group of 4DC
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181C(I) + C(K)305mm Group of 4DCPI,
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183Aggregate Pier305mm Wedge HeadCB
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185Loess + Fibers305mm Single PierC
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187Sand305mm Single PierCBR, %0 2 4
Page 204 and 205:
189Aggregate Pier305mm Group of 4CB
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191C(I) + C(K)305mm Group of 4CBR,
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