Equivalent linear earthquake site characterization of layered soil deposits at Shakardarra and Muzaffarabad

Abstract

The research work relates with the study of site characterization of layered soils. A linear approach is introduced that predicts response of soils against input motions. The equivalent linear damping ratio and normalized shear modulus for different soils are used to test the adequacy of response analysis. For this, two different sites Shakardarra (SHD) and Muzaffarabad (MUZ) on the basis of deposition histories and intensities are selected. Based on the available borehole logs, velocity profiles and geotechnical data of CPT and SPT test the response models are prepared. The equivalent linear site response analysis program (EERA) has been used for this purpose.

Two input strong motions of 0.07 g and 0.17 g of vertical component are introduced as input. The soil profiles are prepared using available set of data by neglecting the effect of water depth. The sites were test for maximum eight iterations and maximum fundamental frequency of 50 Hz for MUZ site and 100 Hz for SHD site is used to analyze the amplification ratio and response spectra against input motion (Inside and outcrop). Site amplification of 1.12-2.36 (clayey sand), 4.13-16.04 (sandy gravel), 1.13-7.15 (dry sand) and 1.24-5.87, is predicted by EERA at (SHD) site for acceleration of 0.17g and 0.007g respectively. While at Muzaffarabad (MUZ) site amplification of 12.189 (gravel, sand and silty clay) for acceleration of 0.17g and 2.224 (gravel, sand and silty clay) is predicted by EERA for acceleration of 0.07g. The results are beneficial for both the researchers and engineers alike.