G MS THESIS_final version_Maxim Prokudin.pdf - Digital Repository ...

12Top1492(a)Applied stress at top of pier (kPa)00 500 1000 1500 2000 250024Settlement (mm)681012Top14Figure 57: Stress-settlement test results for matrix soil used for placement of piers(b)compacted via different shape tamper headsThe stress-settlement tests performed on the piers at this stage were not carried to the fullextent of 12 mm displacement like it was in the later testing stages. Moreover, some piers atthis stage were loaded to a greater extent than others and, thus, the only stiffness comparisonmade was on basis of 2 mm top of the pier displacement (Table 23).Table 23: Stress and stiffness comparison measurements for simulated aggregate piersconstructed via different shape tamper headsPier type 1Aggregate Pier –ConeAggregate Pier -Truncated ConeAggregate Pier –FlatAggregate Pier –WedgeLength (mm)k at δ top = 2 mm(kPa/mm)σ at δ top = 2 mm(kPa)305 188 375610 295 590305 150 299610 285 548305 132 263610 274 570305 195 390610 197 393Loess — 146 291Legend:1 piers were compacted using differentbeveled heads (cone, truncated cone, flat andwedge)k - stiffness modulus (kPa/mm)δ top - deflection at the top of the pier (mm)σ – stress at top of the pier (kPa)Conversions:1 m = 3.3 ft1 mm = 0.0394 in1 kPa = 0.145 psi1 kg/m 3 = 0.0624 pcf