抄録
In discussing the stability of an underground excavation, determining on a failure criterion for the rock mass is the key problem.
A failure criterion for the rock depends upon the relationship between the strength of the rock and the stress in it. On the basis of the failure theories proposed by Griffith, Mohr and Coulomb, the authors have used the following empirical relationship between the principal stresses. It expresses a failure criterion for the rock in the uniaxial compressive strength of the intact rock and the material constants which depend upon the properties of the rock
“The failure criterion”
σ1=σ3+√mσcσ3+sσc2 (1)
where,
σ1 is the major principal stress at failure
σ3 is the minor principal stress at failure
σc is the uniaxial compressive strength of the intact rock
m and s are material constants which depend upon the properties of the rock
While, the failure criterion for a jointed rock mass may be determined by the same relationship to equation (1) to decrease the values of m and s according to the classification of rock masses.
In order to check the applicability of the failure criterion, the authors have mainly made a study of the material constants, m and s, to use about 1, 000 pieces of the results on uniaxial and triaxial tests.
