基于裂面优化破裂单元法的岩体边坡水力耦合失稳机理研究

Complex three-dimensional discontinuity fracture network are found in the jointed rock slope. With the influence of seepage, the water pressures in the fracture network will increase when the strength of the joint will possibly decrease. Meanwhile, the opening, propagation of the fractures will result into further water flow. The influences of this hydro-mechanical effects on stability of the jointed rock slope are not well understood yet. The proposal proposes a coupled hydro-mechanical numerical framework built based on discontinuity layout optimization and cracking elements method, for studying the stability and failure mechanism of jointed rock slope accounting the coupled hydro-mechanical effect. The improved discontinuity layout optimization efficiently determines the potential failure zone and limit results regarding the hydro-mechanical effect. Furthermore, the proposed 3D cracking elements method has good numerical stability and ignorable mesh dependency, which obtains the facture paths and crack widths for coupled hydro-mechanical analysis based on the potential failure zone. With the parameter studies, the influences of fracture networks, seepage, strength of joints on the stability of three-dimensional jointed rock slope will be analyzed and summarized. The proposed method will be validated by the seepage-loading coupled experimental investigations with 3D printed jointed samples. Comparing to other methods, the proposed method is more efficient, which will determine reliable fracture paths. The obtained results will assist the design of reinforcements of the joint rock slopes.

岩体边坡中存在三维复杂裂隙网络，在渗流条件下，岩体边坡的裂隙水压增加，裂隙面强度可能降低；同时，裂隙面的张开、扩展与贯通对渗流有疏导作用。该水力耦合作用对含三维裂隙网络岩体的失稳机理尚不明确。本项目提出基于裂面优化破裂单元法的水力耦合数值计算方法，研究带复杂三维裂隙网络的岩体边坡在渗流条件下的失稳机理。本项目改进的裂面优化方法可以考虑水力作用快速确定潜在破裂区域和极限承载能力，本项目提出的三维破裂单元数值分析方法稳定性好，网格敏感性低，能够根据得到的潜在破裂区域高效确定破裂面的扩展路径，同时获得裂缝宽度并模拟水力耦合过程。通过参数研究，系统分析裂隙网络形态，渗流压力，粘结面性能对于三维岩体边坡稳定性的影响。提出的计算方法将通过3D打印含裂隙网络边坡模型的渗流加载实验进行验证。本方法与现有方法相比，计算效率高，能获得可靠的开裂路径。计算结果可为岩质边坡加固设计提供依据。

我国岩体滑坡灾害事故多，危害大，每年都造成严重财产损失与人员伤亡。岩体滑坡灾害与水力耦合作用及岩体裂隙发展密切相关，针对当前水力耦合作用下三维裂隙岩体失稳机理揭示不完全的现状，本项目提出采用裂面优化法与破裂单元法对三维岩体边坡稳定性展开研究。本项目研究内容包括了破裂单元法、裂面优化法两类计算方法的拓展与创新以及多场耦合计算框架的开发，以及具体工程应用。本项目的研究结果包括：1）通过对比能量耗散以及裂缝开度，证明了破裂单元与传统粘聚力零厚度单元的一致性。2）通过将局部迭代纳入整体迭代，并增加有限的全局自由度，我们将原始的破裂单元法改进为全局破裂单元。3）提出了三角形破裂单元的特征长度构造方法。4）提出了与破裂单元计算框架相适应的能量耗散弧长法迭代数值方法。5）采用破裂单元法模拟了多裂隙岩体及多预制裂隙拟岩石材料单轴压缩条件下的破坏过程。6）将裂面优化法与多场耦合模拟计算框架结合，证明方法本身与多场框架的兼容性。并进行了一些工程应用。7）系统性得总结梳理了裂面优化法，并完成了该方法的第一本中文学术专著。8）与中科院力学所展开合作对环京地区某边坡稳定性展开监测-模拟动态分析，评估了边坡在雨季时的失稳风险。本项目成果以中英文论文、专著、专利的形式进行了归纳与汇总，共发表SCI论文8篇（第一标注7篇），中文专著一本，提交发明专利2项。相关成果的科学意义主要包括：1）强化了破裂单元法的理论完备性，提出了“破裂单元”这一单元类型，使该方法能够在既有有限元平台上开发。2）验证了多物理场框架内的裂面优化法的适定性，为多场裂面优化法的建立与应用奠定了基础。