Empirical methods to determine the rock masses parameters

The deformation modulus of rock mass is a very important input parameter in any analysis of rock mass behaviors which include deformation calculation or stability analysis. In-situ tests,which can determine this parameter directly and is the most reliable methods,are time consuming and expensive. When in-situ tests can?t be made enslaved to something,empirical method,which estimates the value of rock mass deformation modulus on the basis of rock mass classification schemes,would be a good choice. A lot of foreign scholars had established empirical relationships between rock mass deformation modulus and classification system,but the domestic researchers pay little attention in this field. Standard for Classification of Engineering Rock Masses,which was issued in 1994,is the national standard of Chinese. It has been widely used in geotechnical engineering,but the research achievement which related to the rock mass parameters are so little that it is very necessary to study in this area. Using the data by a large number of in-situ tests from large-scale water conservancy and hydropower projects in China,a new relationship between the deformation modulus of rock mass and BQ index is proposed,based upon the principle of statistics and correlation analysis. In order to improve the precision of the empirical formula,a new relationship is proposed between the deformation modulus of rock mass and BQ index,the properties of the intact rock,and it is validated by data from the Three Gorges Project. It would be a useful reference for parameter determination of rock mass in our country.