考虑黏聚力损失的岩石残余强度模型与数值验证

岩石的峰后力学性质对于维持岩土工程结构的稳定性至关重要,为研究岩石峰后残余强度的确定方法,利用岩石进入残余强度阶段后摩擦力强度增强、黏聚力强度减小的特点,通过假定岩石进入残余变形阶段后黏聚力强度为0,基于HOEK-BROWN破坏准则,建立了一种考虑岩石进入残余强度阶段时黏聚力损失的岩石残余强度模型。用该模型拟合完整粗晶大理岩的室内三轴试验结果,并与已有M-C模型和Joseph模型等方法对比分析,讨论了模型的优势。将该模型嵌入到FLAC3D软件中进行数值模拟验证,结果表明:该岩石残余强度模型能正确反映不同围压条件下岩石力学响应的基本规律,得到的残余强度值与试验结果吻合良好,其随围压变化的拟合曲线符合试验数据拟合结果的特点,即经过原点及高围压条件下未出现应变硬化现象。研究成果对分析岩石残余强度的确定方法具有较强的参考价值或指导意义。

Cohesive force loss-considered rock residual strength model and its numerical verification

The post peak mechanical properties of rock are important for maintaining the stability of rock and soil engineering structures. In order to study the method for determining the post-peak residual strength of rock，a rock residual strength model under the consideration of the cohesive force loss when rock comes into the stage of residual strength stage is established based on the HOEK － BＲOWN failure criterion in accordance with the characteristics of that the strength of the frictional force is enhanced and the strength of the cohesive force is decreased after rock coming into its residual strength stage through the consumption of that the rock cohesive force strength is 0 after it coming into the residual deformation stage. The results from the indoor triaxial testmade on the intact coarse-grained marble are fitted with this model and then compared with those from the methods of M － C model，Joseph model，etc. for discussing the advantage of this model. A numerical verification is made on this model by embedding it into the FLAC3D software，from which the result shows that this rock residual strength model can correctly reflect the basic law of the mechanical response of rock under various confining pressure conditions and the obtained value of the residual strength is better coincided with that from the relevant test，while the fitting curve variated along with its confining pressure accords with the characteristics of the fitting result of the test data as well，that is to say，no strain hardening phenomenon appears through the original point and under the high confining pressure condition. The study result has higher referential value and guiding significance for the analysis on the method of determining rock residual strength.