On The Shear Strength Of Dam Foundations With Interbedded Weak Seams

In this paper, the author suggests to use the yield limit as the shear failure criterion for the soft rocks of plastic-failure type. A method is proposed to determine this characteristic point, which has been adopted in several projects. The causes of scattering of the in situ shear test results are investigated, and “The method of friction-shear correction” is proposed. The practical records are presented to illustrate the advantage of reducing the scattering and artificial errors in the results. 261 sets of in situ test result on 56 engineering projects in China are analysed. The two formulas for checking the stability of the dam against sliding are suggested. However, it is not yet applied to engineering practice due to its incomformity with the current specification. But preliminary trial computations show that the formula for brittle-failure type proposed by the auther is very close to that specified by the Russian standard (CH123-60); the corresponding formula for plastic-fai-lure type is close to the friction formula without considering the adhesion, if the height of dams is within the range of 40-110 meters and corresponding factor of safty is 1.2-1.4.