基于上限有限元运动单元法的堆积体边坡非线性失稳机理研究

The accumulation body, a common adverse geological body in dangerous mountain areas, poses a serious threat to the construction and operation of transport in mountain areas. Since the existing theories cannot describe and generalize the characteristics of accumulation body with high heterogeneity, discontinuity, non-linearity, it is important and imperative to study the nonlinear instability mechanism of accumulation slope for its safety assessment and dispensarization under complex conditions. In this research project, by integrating the respective merits of the kinematical element method and the finite limit element upper method, the nonlinear programming mathematical model and solving format of the finite limit element upper method with adaptive grid and reset velocity discontinuity line is established. Parameter inversion analysis model of nonlinear yield strength of accumulation slope under complex conditions is established based on the system minimum energy consumption principle. The failure modes and internal dissipation of energy distribution in accumulation body is obtained and the distinction between the key parts of support part and mechanical weak regions is also clarified after strain localization being taken into account and the implementation of stability calculation and parametric analysis of accumulation slope under complex conditions (arbitrary boundary, layered geotechnical and nonlinearity yield characteristics of material), and then the occurrence and spread law of the nonlinear instability mechanism of the accumulation of body is clarified. Meanwhile, the comparison verification is carried out between indoor and outdoor experiments and numerical simulation, and finally the engineering applied research can be carried out. The results of research projects can provide important technical support for the safety assessment and strengthening of the complex accumulation slope.

堆积体是艰险山区常见不良地质体，严重威胁着山区交通运输的建设与运营。鉴于现有理论尚不能对具高度非均质、非连续、非线性的复杂堆积材料进行描述和概化，开展复杂条件下堆积体边坡非线性失稳机理的研究对其安全评估和防治具有重要意义且势在必行。本项目通过融合运动单元法和上限有限元法的各自优点，建立起具有网格自适应与速度间断线优化重置特性的上限有限元运动单元法非线性规划数学模型和求解格式；基于系统耗能最小原理，建立复杂堆积体滑坡非线性屈服参数反演分析模型；考虑应变局部化，进行复杂条件（任意边界、岩土分层、材料非线性屈服特性等）下堆积体边坡稳定性计算与参数分析，获得堆积体破坏模式和内部耗散能分布，界定岩土承载的关键部位与力学薄弱区域，进而阐明堆积体非线性失稳机理的发生与扩展规律。同时采用室内外试验和数值模拟进行对比校证，最后开展工程应用研究。本项目研究可为复杂堆积体边坡安全评估和防护加固提供重要技术支撑。

本研究采用上限有限元运动单元法及极限分析上限法，结合可靠度理论对边坡破坏模式及非线性失稳机理等基础性问题开展研究，取得了预期的研究成果，完成了预期考核目标。取得的主要研究成果如下所示：.（1）将刚体平动运动单元理论与上限有限元理论相融合，通过引入非线性破坏准则，提出了基于非线性规划模型的刚体平动运动单元上限有限元法及计算流程。.（2）为准确分析坡体稳定性并获得相应精细破坏模式，提出了一种上限有限元非结构化六节点三角形单元网格自适应加密策略。通过引入网格自适应加密评判准则，完成了二维上限有限元通用稳定性计算程序的编制，并采用实例验证了其有效性。.（3）基于可靠度原理，提出了以可靠度指标最小为参数反演标准的滑坡抗剪强度反演能耗分析方法；基于可靠度反分析方法在二、三维滑坡工程中的应用，解决任意单一二、三维滑动面滑坡抗剪强度参数反演问题。.（4）提出了基于运动单元法的均质化假定堆积体边坡稳定性分析方法。同时，以堆积体边坡的一种典型形式土石混合体边坡为例，建立了土石混合边坡有限元网格分析模型并采用有限差分强度折减法对土石混合边坡进行稳定性分析，由此提出了一种堆积体边坡（土石混合体边坡）稳定性的数值分析方法；.（5）综合考虑多复杂因素效应开展了岩土边坡稳定性能耗分析模型建立与优化，系统完善了传统刚体极限分析理论。.（6）基于可靠度理论及极限分析方法，开发了一款用于边坡抗剪强度参数反演分析的软件，实现了计算结果与临界滑裂破坏面图形的可视化输出。.（7）在项目执行期内（2012.09.01-2015.12.31）发表学术论文34篇，其中SCI/EI检索论文26篇(其中录用待刊2篇)，CSCD源刊论文6篇（其中录用待刊1篇）；另外，SCI返修2篇，EI外审3篇。