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147Another observation was made, where the trend of reduction of the group efficiency withincreasing amount of load was noticed (Table 27). Therefore, piers and groups of piersfeatured greater group efficiency at service load conditions and much lesser efficiency atfailure. As a result, it was concluded that the group efficiency became smaller as the loadimposed on a group of piers approached critical or ultimate condition.Group efficiency values obtained for all 305 mm groups of piers at 5 mm and 10 mm levelsof settlement were observed to consistently vary within the margin of 2.0-2.8 for groupefficiency calculated in terms of single pier. Therefore, short groups of piers at 5 mm and 10mm levels of settlement had a consistent group efficiency value ranging between two andthree independently of the number of piers within the group. Similarly, the long 610 mmgroups of piers featured consistent group efficiency values ranging between 1.0 and 1.9 at 5mm and 10 mm levels of settlement. Thus, the group efficiency for groups of long piersvaried between 1 and 2 at the level of 5 mm and 10 mm levels of settlement independently ofthe number of piers contained within the group.For the groups efficiency calculated in terms of unit cell, the values were found to beconsistently lower than 1.0 for most of the groups of piers. Consistently with Table 27 groupefficiency results, the piers within the short groups of piers were found to be more efficiencythan in long groups of piers. No particular trend was noticed with respect to group efficiencyrelated to the amount of pier settlement.C(I) + C(K) - Stress-SettlementAs outlined in Figure 89, the stress-settlement curves were plotted and grouped by length.The relative position of the plotted data points for the groups of piers was observed to behavein the expected manner, where the greatest amount of stress was carried by the group of sixpiers and the least by the group of two. As one would expect, the groups of shorter 305 mmpiers were also observed to support less load than long piers at the same amount ofsettlement. However an anomaly was notices where the unit cell has shown to outperformed
148single pier for both 305 mm and 610 mm long piers. More testing would be required toconfirm the trend and identify cause of the unit cell cementitious pier to have higher bearingcapacity.The calculated stiffness ratio results for unreinforced soil and pier supported conditions werecalculated per Equation 20 and summarized in Table 38.Pier typeTable 38: Stress concentration calculations for groups of C(I) + C(K)σ at δ topσ at δ top σ at δ topLength= 10= 2 mm = 5 mm(mm)mm(kPa) (kPa)(kPa)σ at δ top σ at δ topLengthPier type= 2 mm = 5 mm(mm)(kPa) (kPa)σ at δ top= 10mm(kPa)C(I) + C(K)Single Pier305 908 1,418 1,806 C(I) + C(K) 305 1,921 3,151 3,609610 1,083 1,841 2,065Group of 4610 N/A N/A N/ALoess - 278 685 1,101 Loess - 278 685 1,101n. stiffnessratioC(I) + C(K)Unit Cell- 3.3 2.1 1.6 n. stiffness - 6.9 4.6 3.3- 3.9 2.7 1.9ratio- N/A N/A N/A305 640 968 1,147 C(I) + C(K) 305 2,377 3,647 4,225610 794 1,241 1,460Group of 5610 3,148 4,148 4,630Loess - 278 685 1,101 Loess - 278 685 1,101n. stiffnessratioC(I) + C(K)Group of 2- 2.3 1.4 1.0 n. stiffness - 8.6 5.3 3.8- 2.9 1.8 1.3ratio- 11.3 6.1 4.2305 1,266 2,023 2,400 C(I) + C(K) 305 3,355 3,820 4,096610 1,542 2,209 2,869Group of 6610 2,896 4,818 5,672Loess - 278 685 1,101 Loess - 278 685 1,101n. stiffnessratio- 4.6 3.0 2.2 n. stiffness - 12.1 5.6 3.7- 5.5 3.2 2.6ratio- 10.4 7.0 5.2Legend:δ top - deflection at the top of the pier (kPa)σ – stiffness of the pier (kPa)n –stiffness ratioCon<strong>version</strong>s:1 m = 3.3 ft1 mm = 0.0394 in1 kPa = 0.145 psi
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
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19Soil conditions at the site were
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Settlement (mm)Settlement (mm)10202
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23Site soil conditions were describ
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25Article#ReferenceTable 2: Case st
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27Article#7ReferenceHughes andWithe
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29replaced with method of freezing
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UNREINFORCED COLUMNNO COLUMNREINFOR
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33The load carrying capacity was fo
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35Case 5 - Bachus and Barksdale, 19
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37full depth of the consolidated la
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39CHAPTER 3: RESEARCH METHODOLOGYCr
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41itself was designed to be support
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43While it is obvious that the chan
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45To perform all the required testi
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47In the areas where access was lim
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49CBR from DCPThe California Bearin
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305 mm610 mm305 mm610 mm305 mm610 m
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53The process of using the Shelby t
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15881556144815591597154915271586158
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57Table 14: Top and bottom UC loess
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59Data Collection and SensorsHaving
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61Micro Epsilon displacement transd
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63plate down the cavity through man
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65Beveled Tamper HeadsThe other asp
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67All, aggregate, cementitious and
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69DAQ Data CollectionWhile performi
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71space in the test bed (See Figure
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73(a)(b)(c)Figure 42: Test bed grou
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75CHAPTER 4: MATERIALSThe materials
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7710080LL = 31PI = 7Pass. #200 = 98
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79the second stage of testing. Mois
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81Knowing the gradation characteris
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83More importantly, the performed d
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85Figure 49: Cement type I compound
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87As the expansive and contractive
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89Figure 55: 19 mm polypropylene fi
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91CHAPTER 5: TEST RESULTS AND ANALY
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93Applied stress at top of pier (kP
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95Figure 60: Stress-settlement test
Page 112 and 113: 97Figure 62: Stress-settlement test
Page 114 and 115: 99Figure 64: 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
Page 134 and 135: 119Settlement (mm)0246810Applied st
Page 136 and 137: 121The group efficiency results wer
Page 138 and 139: 123Pier typeAggregate PierUnit Cell
Page 146 and 147: 131Applied stress at bottom of the
Page 148 and 149: 133Table 33: Group efficiency compa
Page 150 and 151: 135Having a limited amount of exper
Page 152 and 153: 137Stiffness, kPa/mm600500400300200
Page 154 and 155: 139In case with the piers consistin
Page 156 and 157: 141Table 36: Stiffness ratio calcul
Page 158 and 159: 143Some of the loess composition pi
Page 160 and 161: 145Pier typeAggregatePierSingle Pie
Page 164 and 165: 149As previously outlined, the stif
Page 166 and 167: 151pier group efficiency values wer
Page 168 and 169: Stiffness Ratio1538Figure 91: Stiff
Page 170 and 171: 155CHAPTER 7: SUMMARY AND CONCLUSIO
Page 172 and 173: 157MaterialsLoess-CementVery intrig
Page 174 and 175: 159Groups of PiersGroup of Aggregat
Page 176 and 177: 161CHAPTER 8: FUTURE RESEARCHThe fu
Page 178 and 179: 163Black, J.A., Sivakumar, V., Madh
Page 180 and 181: 165Hanlong, L., An, D., and Yang, S
Page 182 and 183: 167Randrup T.B., and Lichter, J.M.
Page 184 and 185: 169Yeh, Y.K., and Mo, Y.L. (2005).
Page 186 and 187: 171Group EfficiencyAggregate Pier G
Page 188 and 189: 173Aggregate Pier305mm Wedge HeadDC
Page 190 and 191: 175Loess + Fibers305mm Single PierD
Page 192 and 193: 177Sand305mm Single PierDCPI, mm/bl
Page 194 and 195: 179Aggregate Pier305mm Group of 4DC
Page 196 and 197: 181C(I) + C(K)305mm Group of 4DCPI,
Page 198 and 199: 183Aggregate Pier305mm Wedge HeadCB
Page 200 and 201: 185Loess + Fibers305mm Single PierC
Page 202 and 203: 187Sand305mm Single PierCBR, %0 2 4
Page 204 and 205: 189Aggregate Pier305mm Group of 4CB
Page 206 and 207: 191C(I) + C(K)305mm Group of 4CBR,
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