| Test Information | |
| Year | 1998 |
| Test Location | Salt Lake City International Airport, Utah, USA |
| Test Type | Large Scale |
| Reference | Rollins, K. P., Peterson, K. T., and Weaver, T., J. (1998). “Lateral Load Behavior of Full-Scale Pile Group in Clay.” ASCE Journal of Geotechnical and Geoenvironmental Engineering, 124(6), 468-478. |
| Purpose | Analysis of the behavior of a group pile in clay |
| Keywords | p-y curves;pile groups; p-multipliers; group efficiency; clay; lateral loads |
| Soil Information | |
| Soil Type | Clay |
| Soil Description | The soil profile near the surface consists of layers of silt and clay underlain by a sand layer. The water table was located near the natural ground surface during the testing. |
| Soil Classification | UPPER LAYERS: ML, CL-ML, CL; LOWER LAYERS: SP or SM |
| Soil Properties | UPPER LAYERS: undrained shear strength=25-100 kPa; LOWER LAYERS: Dr=65-85% |
| Type of Soil Investigations | SPT, CPT, DMT, PMT, VST, downhole shear velocity analysis |
| Attachments |  Rollins_SPT.tif |
Rollins_water_content.tif | |
Rollins_SU.tif | |
 Rollins_Soil_properties_updated_w.xlsx | |
| Pile Information | |
| Pile Material | Steel with Grout Fill |
| Pile Placement Method | Driven |
| Material Properties | STEEL: Es= 200 GPa; Fy=331 Mpa ; CONCRETE: compressive strength= 20.7 MPa (3000 psi), elastic modulus= 17.5 GPa |
| Pile Cross Section | Circular |
| Outside Section | 30.5 cm |
| Wall Thickness | 9.5 mm |
| Test Configuration | |
| Test Configuration | Pile Group |
| Pile Spacing | 3D |
| Group Arrangement | Box Arrangement |
| Test Columns | 3 |
| Test Rows | 3 |
| Head Boundary Condition | Free |
| Loading | |
| Type of Loading | Static One-Way Cyclic |
| Axial Load | N/A |
| Load Application | The load was applied to the group using a 1.24 MN capacity hydraulic jack. A W36*150 beam was used to distribute the jacking force to the sheet pile reaction wall. Torsional rotation did not exceed 0.075° for any loading. |
| Test Results | |
| Max Top Displacement | 6 cm |
| Deflection | 0.20 diam |
| Attachments | Rollins_load_deflection_curves_rows.tif |
Rollins_load_deflection_curves_single_group.tif | |
Rollins_load_deflection_curves.xlsx | |
Rollins_load_deflection_curves_rows.xlsx | |
| Analysis Method | |
| Software Used | LPILE (Reese and Wang 1994); GROUP (Reese et al. 1996) |
| Group Efficiency Factor | 0.59-0.80 |
| P-Multipliers (lead, 2nd, 3rd, n-th rows) | 0.6, 0.38, 0.43 |
| P-Y Curves Model | Matlock (1970) for clay layers; Reese et al. (1974) for sand layers |
| Conclusions | |
| Comparisons | The adjusted p-multipliers are significantly lower than the default values employed in the GROUP. Software's values are at the low end of the range of p-multipliers obtained from available full-scale tests. |
| Outcomes | 1. The deflection of closely spaced pile group (spacing = 3 pile diameters) is 2-2.5 times more than the isolated single pile under the same average load. 2. Load capacity in the pile group is a function of row position. For a given deflection, piles in trailing rows carried less load than piles in the leading row, and piles in all rows carried less load than the single isolated pile due to group effects. 3. Bending moments for piles in the group were significantly higher (50-100%) than those in the isolated single pile. The reduction in load-carrying capacity due to group effects also increased the depth of the maximum moment. 4. The p-multiplier concept provides a reasonable means of accounting for the reduction in capacity produced by group effects and the resulting lateral group behavior. |
