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Abstract To obtain the deformation modulus of deep rockmass，deformation tests under different lateral pressures are carried out for medium size marble samples using the true triaxial test machine. The comparison tests for the same sample under the same lateral pressure and different lateral pressures are conducted emphatically. The tests indicate that：(1) There is significant nonlinear relationship between deformation modulus and lateral pressure of the marble. The deformation modulus of marble no longer increases with the increase of the lateral pressure after the lateral pressure reaches 30 MPa；and the lateral pressure reflects the weakening degree of marble when the marble breaks away from parent rock. (2) Then，the relationship between deformation modulus and three-dimensional stresses of marble is obtained. Based on the value of in-situ stress at the site of the sample，the deep marble deformation modulus of 66.7–68.2 GPa is calculated. (3) The calculated value of deformation modulus coincides well with the value obtained by other indirect methods；and it is significantly higher than values of conventional indoor and field tests. The above results indicate that the mechanical properties of deep rock mass will be weakened after stress relief；and the weakening degree is related to the in-situ stress. This method is of great importance for researching deformation characteristics of rock mass under high in-situ and extremely high stress and slopes with larger deviatoric stress.
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Received: 03 June 2013
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2013, Vol. 32 
