Estimation of geotechnical parameters using Taguchi's design of experiment (DOE) and back analysis methods based on field measurement data: Case study: Tehran Metro line no. 7

Estimation of geomechanical parameters is a challenging task in geotechnical engineering. This paper aims to estimate the geotechnical parameters of soil layers in the Tehran Metro line no. 7 based on the field measurement data. In this study, the design of experiment (DOE) method is utilized for estimation of the geotechnical parameters. The geotechnical parameters such as the modulus of elasticity (E), cohesion (c), and the internal friction angle (phi) are estimated using Taguchi's DOE method and displacement-based back analysis. The results of the DOE experiments are examined by the analysis of range (ANORA) to improve the accuracy of the optimization. Results show that Taguchi's DOE technique offers more effective and precise estimation of the geotechnical parameters than a displacement-based back analysis approach. Finally, the optimal combination of geotechnical parameters is proposed based on results analysis of Taguchi's DOE and back analysis method. It is shown that the combination of the obtained geotechnical parameters from Taguchi's DOE method is closer to the field measurement data.