2009 年 49 巻 2 号 p. 249-258
The correction factor (ηie) for the ultimate bearing capacity of a footing placed adjacent to a slope, taking into account the combined effect of horizontal and vertical seismic loads, represented by horizontal and vertical seismic coefficients, kh and kv, respectively, was derived using a modified Janbu's slice method. The influence of slope angles ‘α’ on the values of ‘ηie’ are studied here. It was found that the values of ηie can be expressed as an exponential function of ‘kh/(1-kv)’ and ‘α’, with a measurable interdependency between ‘α’ and ‘ηie’. The influence of ‘α’ on the value of ‘ηie’ increases as the input value of ‘kh/(1-kv)’ increases. Equations derived based on the analytical results are proposed to account for this effect. Based on the analyses of 11 near-fault seismographers obtained in the 1999 Chi-Chi earthquake in Taiwan, a ratio between the vertical and the horizontal seismic coefficients, λ, of between ±0.25 is suggested for including the combined effect of vertical and horizontal seismic forces in evaluating the seismic bearing capacity of footings located in near-fault areas.
