非线性强度参数对高土石坝坝坡稳定性的影响

堆石料在高应力状态下，其抗剪强度具有明显的非线性。使用对数形式的非线性强度准则得到的坝坡计算安全系数要高于按线性强度准则得到的计算安全系数。现行规范所规定的许可安全系数，是与多年来大量使用偏低的线性强度指标所作的稳定计算相适应的，偏于保守：改用非线性强度后应作适当的提高。对采用非线性强度计算的安全系数比采用线性强度计算的安全系数提高程度进行了统计分析，给出了用非线性强度指标进行稳定分析的安全系数取值标准的建议值。

EFFECT OF STRENGTH NONLINEARITY ON SLOPE STABILITY OF HIGH ROCKFILL DAM

The results of many large scale triaxial tests indicate that the Mohr failure envelopes for rockfill exhibit significant nonlinearity particularly in low and medium stresses,which means that,in low confining pressure,the angle of internal friction is relatively high,but in high confining pressure,it is relatively low. The strength of rockfill exhibits nonlinearity and the curved failure envelope could be described by logarithmic relationship. However,conventional strength is linear with an average friction angle. A computer program is developed for the stability analysis of circular arc slope with strength nonlinearity taken in account. The comparison of safety factors of 7 high rockfill dams with nonlinear strength and linear strength indicates that safety factor of non-linear analysis is bigger than that of linear analysis. The value of nonlinear safety factor is increased with increment of 20%. The slip surface of linear analysis is shallow,but that of nonlinear analysis is deep. The allowable safety factor based on linear rule should be properly increased with increment of 8%,according to the study result of this paper.