Determining the Geomechanical Parameters of the South Part of Isfahan Subway Host Rock Using Back Analysis

In this article First geotechnical parameters of host rock of the south part of Isfahan subway net are studied then the main goal of instrumentation is described and installed instruments are introduced and some of results are presented. Different methods of back analysis and the way of optimizing these methods and the advantages and disadvantages regarding to are described as well. In continue three dimensional modeling which is used in this study is discussed. Back analysis is implemented to determine deformation modulus, cohesion and internal friction of the host rock. Utilizing the numerical modeling and applying least square method deformation modulus, cohesion and internal friction angle of the host rock are obtained 30 degrees, 150 KPa and 1.5 GPA respectively. Utilizing the optimization procedures and applying weighted least square and minimizing the maximum error, deformation modulus, cohesion and internal friction angle of the host rock are obtained 35 degrees, 300 KPa and 1.5 GPa respectively. These results show the least sensitivity to internal friction angle and the most to deformation modulus and Cohesion. The low sensitivity to internal friction angle may be due to the low overburden.