坝基不同倾角软弱夹层的破坏模式及D-C模型参数研究

Failure modes and constitutive model for weak interlayer of dam foundation with different inclination angles

坝基岩体中的软弱夹层对抗滑稳定影响重大,因此对其破坏模式及本构模型参数的研究具有重要意义。采用软弱夹层重塑样进行三轴压缩试验,下部未泥化部分采用泥化部分土掺入20%水泥代替,上部采用泥化部分土制样,泥化部分与未泥化部分交界面分别制成0°,30°,45°,60°倾斜面并作粗糙处理模拟实际界面特性。试验结果表明:含不同倾角结构面的软弱夹层试样临界角范围为58.3°~61.7°,当结构面倾角介于临界角范围之内时,软弱夹层试样沿结构面破坏,当结构面倾角位于临界角范围之外时,软弱夹层试样在上部泥化部分土中破坏;对软弱夹层试样三轴试验ε((σ1-σ3))–ε1关系曲线进行线性拟合,结果表明,随围压增加,试样初始切线模量及极限破坏强度均增加,根据试验结果得出了相应的D-C模型参数并将其应用于坝基抗滑设计中,取得了良好效果。本研究成果对坝基软弱夹层的抗滑设计及同类软弱夹层工程性质的研究具有一定参考价值。

The soft interlayer in the dam foundation rock mass has a great influence on the stability of the dam foundation against sliding,thus the researches on its failure modes and constitutive model parameters are of great significance.The remolded sample is adopted for triaxial tests:the lower part is made up of clay and cement of 20%and the upper is made by clay,the interface is made into inclined planes of 0°,30°,45°and 60°and roughed to simulate the real interface characteristics.The test results show that the critical angle range of weak-interlayer samples with different dip angles is 58.3°~61.7°,when the inclination angle of the structural surface is in the range of the critical angle,the soft-interlayer sample is destroyed along the structural surface,otherwise the failure surface appears in the upper part of the muddy soil.Linear fitting of the triaxial testε/(σ1-σ3):ε1,and the results show that as the confining pressure increases,the initial tangential modulus and the corresponding peak intensity of the sample increases.According to the test results,the corresponding D-C model parameters are obtained and applied to the anti-sliding design of the dam foundation,and good results are obtained.The research results have a certain reference value for the anti-slip design of the dam foundation and the researches on similar soft-interlayer projects.