Fully coupled site response analysis for mild sloping ground
by Ko Chi Pui
M.Phil. Civil Engineering
xxvi, 195 leaves : ill. ; 30 cm
Earthquakes always cause severe damages to infrastructures. Serious destruction of structures were found in the likes of Alaska Earthquake, Niigata Earthquake, Tangshan Earthquake, Hyogo-Ken Nanbu Earthquake and Chi-chi Earthquake....[ Read more ]
Earthquakes always cause severe damages to infrastructures. Serious destruction of structures were found in the likes of Alaska Earthquake, Niigata Earthquake, Tangshan Earthquake, Hyogo-Ken Nanbu Earthquake and Chi-chi Earthquake.
Earthquake induced soil liquefaction makes soil behaves like liquid and thus significantly reduces the soil strength. The mechanism of soil response in earthquake becomes increasingly important to researchers. In this study, modified SUMDES analysis is used to investigate the earthquake response of soil in a mild slope. SUMDES (Li et al. 1992) is a verified one-dimensional program for level ground analysis during earthquakes.
Modification of the program is made by introducing an inclination angle to the analysis. A constitutive model proposed by Li and Dafalias (2000) and the linear representation of cohesionless soil (Li et al. 1998) are used for the analysis. The program simulations are compared with the centrifuge test results from the VELACS project and the Public Works Research Institute. Overall, the modified SUMDES program gives reasonably well predictions when compared with the experimental measurements.
Parametric studies on the influences of soil density, slope inclination and shaking magnitude to dynamic responses are made based on the modified SUMDES program. It is found that soil densities can influence dynamic responses heavily. When soil is loose, flow failure can be easily triggered by earthquake when the static driving force is greater than soil residual strength. Significant reduction in acceleration and a larger lateral displacement are observed. On the contrast, higher acceleration, limited lateral displacement and relatively smaller excess pore pressure are resulted in slopes with dense soil. Slope inclination also pays an important role in dynamic response. Cyclic mobility happens during shear for medium dense sand on steeper slopes. Thus, dilation and phase transformation can be found at an earlier stage. Shaking magnitude also strongly influences dynamic responses. Larger shaking causes stronger shear before soil liquefaction. Higher soil liquefaction can be found in pre-liquefaction stage.