Seismic passive resistance by pseudo-dynamic method
The pioneering work on earthquake-induced lateral earth pressure under active and passive conditions acting on a retaining wall was reported by Okabe (1926) and Mononobe & Matsuo (1929), based on a pseudo-static approach by following Coulomb’s earth pressure analysis under static conditions, and is known as the Mononobe–Okabe method (Kramer, 1996). But in the pseudo-static method, the dynamic nature of earthquake loading is considered in a very approximate way. The phase difference due to finite shear wave propagation behind a retaining wall can be considered using a simple and more realistic pseudo-dynamic method, proposed by Steedman & Zeng (1990). Again Zeng & Steedman (1993) compared the theoretical results with centrifuge model test results to validate the pseudo-dynamic method. Steedman & Zeng (1990) and Choudhury & Nimbalkar (2005) considered the case of active earth pressure behind a retaining wall by a pseudo-dynamic method of analysis. But the case of passive earth pressure or passive resistance behind a retaining wall by this pseudo-dynamic method has not received any attention so far. Hence, in this paper, the pseudo-dynamic method is applied to determine the seismic passive resistance behind a rigid retaining wall. Steedman & Zeng (1990) did not consider the effect of vertical seismic acceleration on the active earth pressure, which was corrected by Choudhury & Nimbalkar (2005). In this paper, the effects of both horizontal and vertical seismic accelerations on passive earth pressure are considered. Also, as an improvement over the Steedman & Zeng (1990) analysis, the effect of variation of different parameters such as wall friction angle , period of lateral shaking T, soil friction angle , horizontal and vertical seismic coefficients kh, kv, shear wave velocity Vs and primary wave velocity Vp are considered in the present analysis.