Mohammad Doostmohammadi - School of Mining, College of Engineering, University of Tehran, Iran
Ahmad Reza Jafari - School of Mining, College of Engineering, University of Tehran, Iran
Omid Asghari - School of Mining, College of Engineering, University of Tehran, Iran- Simulation and Data Processing Laboratory, School of Mining Engineering, University College of Engineering, University of Tehran, Iran

Uniaxial compressive strength (UCS) is one of the most significant factors on the stability of underground excavation projects. Most of the time, this factor can be obtained by exploratory boreholes evaluation. Due to the large distance between exploratory boreholes in the majority of geotechnical projects, the application of geostatistical methods has increased as an estimator of rock mass properties. The present paper ties the estimation of UCS values of intact rock to the distance between boreholes of the Behesht-Abad tunnel in central Iran, using SGEMS geostatistical program. Variography showed that UCS estimation of intact rock using geostatistical methods is reasonable. The model establishment and validation was done after assessment that the model was trustworthy. Cross validation proved the high accuracy (98%) and reliability of the model to estimate uniaxial compressive strength. The UCS values were then estimated along the tunnel axis. Moreover, using geostatistical estimation led to better identification of the pros and cons of geotechnical explorations in each location of tunnel route.

Behesht-Abad tunnel project, Uniaxial Compressive Strength, Geostatistical estimation, SGEMS