Investigating the Overburden Correction Factor (Kσ) in silty sand using centrifuge modeling
Year: 2026
Type: article
Abstract: This study involves a comprehensive series of four centrifuge experiments, designed to closely simulate a 5-m-thick layer of silty sand subjected to a range of drainage conditions—both single and double—and exposed to effective overburden pressures of approximately 100 and 600 kPa (corresponding to 1 and 6 atm, respectively). The primary aim was to investigate the pore pressure behavior of silty sand when subjected to base acceleration under varying overburden pressures, specifically under conditions of low and high overburden pressure. A key focus was the examination of the Overburden Pressure Correction Factor ( K σ ), particularly with respect to field-like drainage scenarios, encompassing both single and double drainage configurations. In the single drainage experiments, the silty sand layer was set up with an impervious bottom boundary and a pervious top boundary, while the double drainage configuration permitted drainage at both the top and bottom boundaries of the silty sand layer. The saturation process utilizing a viscous fluid was carried out from the base of the silty sand layer to ensure full saturation for the four tests. The experimental analysis compared the silty sand response under the different overburden and drainage conditions by evaluating detailed time histories and profiles of excess pore pressure together with cyclic stress ratios (CSR), which were calculated using the System Identification (SI) technique. During shaking, the single- and double-drainage tests showed generally similar pore-pressure buildup trends. During dissipation, however, the double-drainage configuration produced faster pore-pressure reduction, particularly near the lower boundary of the silty sand layer, demonstrating the effectiveness of the bottom drainage path. The field overburden pressure correction factors, field K σ , derived from the centrifuge tests were consistently below 1.0 for both drainage scenarios. These values differ from previous clean-sand centrifuge results obtained under similar drainage configurations, where field K σ values greater than unity were reported. For the tested 5 m low-permeability silty sand layer, the obtained field K σ values were only slightly higher than the current-practice undrained laboratory value at 6 atm. This suggests that the tested silty sand configuration responded close to the conventional undrained K σ trend under the examined boundary conditions. The results highlight the combined influence of drainage conditions and soil permeability on the evaluation of field K σ .
Language: English
Subfield: Civil and Structural Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,900
OpenAlex ID: W7213964952