Back calculating the seismic shear strengths of the Tsaoling landslide associated with accelerograph and GPS data

In this study, the seismic displacement-based back-calculation is discussed and is conducted to analyze the shear strength parameters of the Tsaoling landslide under the impact of the Chi-Chi earthquake. Since the intensive earthquake tilted the ground shifted velocity when integrating seismic acceleration records, the co-seismic displacements measured by neighboring GPS stations played an essential role on baseline corrections of the acceleration time-history adjoining the Tsaoline landslide. In addition, an analysis process of combining empirical formula with Newmark’s sliding model simplifies the back-calculation procedure that only assuming the cohesion is required to calculate the internal friction angle of the sliding surface. Although the baseline correction changes the time-history of seismic accelerations, it has an insignificant impact on calculating the shear strength parameters of the Tsaoling landslide. The analysis results indicate that the cohesion is 0 kPa and the internal friction angle is 27.5° for the sliding surface.