环锚衬砌的预应力荷载传递机理及其应力状态解析

In traditional pre-stressed structure system, stress is mainly generated in the interaction of the anchoring end and stressing area. The encircled anchored lining close the anchor cable according to anchor head walking, which could transfer the circumferential stress into radial one, result in the pre-stress of lining structure. The study of stress transfer mechanism is a critical part in analyzing the mechanical characteristics of encircled anchored lining and in structure designing. Based on in-situ monitoring data and discrete-continuous coupling numerical method, this project analyzes the pre-stress transfer mechanism inside lining, the same mechanism between the encircled anchor and lining, the influence rules of surrounding rock boundary effect, to study the pre-stress transfer mechanism of encircled anchor-lining structure system. On the basis of above analyses, an expression of monocyclic anchor and polycyclic anchor pre-stress equivalent load method is proposed, a numerical model of anchor-lining structure under complex loading condition is established by considering the influence of surrounding rock yield situation in load-unload transition and the principal stress transformation. A stress state analytical equation is proposed which could be generally applied in engineering. This research provides a theory basis for anchor-lining structure designing and engineering applications, it also provides an analytical reference for numerical simulations in engineering.

环锚衬砌通过游动锚头把锚索封闭成环，主要利用套箍效应将锚索环向拉力转化为径向荷载使衬砌产生预应力，预应力荷载传递机理及其应力状态解析是确定环锚衬砌力学特性的关键。本项目基于离散-连续耦合数值方法研究环锚与衬砌的预应力荷载传递特性，结合现场监测验证和分析衬砌内部预应力荷载传递规律、围岩边界效应的影响规律，揭示环锚衬砌结构体系预应力荷载传递机理，提出单环锚及多环锚预应力等效荷载表达方法。考虑围岩加卸载屈服状态转变和主应力顺序转换对预应力场的影响，建立联合承载条件下的环锚衬砌结构力学计算模型，并建立环锚衬砌应力状态解析解。项目研究成果可为环锚衬砌结构设计及其工程应用提供理论支撑和参考。

新型预应力环锚钢筋混凝土衬砌具有抗高内压的能力，可为解决“覆盖层薄、地质条件差、内水压力高”的大断面压力隧洞支护问题，提供新途径，但力学性能的复杂性和不确定性阻碍了其广泛应用。为了进一步摸清环锚、混凝土衬砌和围岩之间的实际相互作用，在吉林省某6.8米直径输水隧洞中，利用环形扁千斤顶进行了创新性的环锚衬砌大型原位加载试验。揭示了张拉期和运行期的环锚受力变化规律、预应力筋后张过程中衬砌内预应力重分布特征以及内水荷载作用效果。以此为基础，基于离散-连续耦合数值方法研究环锚与衬砌的预应力荷载传递特性，结合现场监测验证和分析衬砌内部预应力荷载传递规律、围岩边界效应的影响规律，揭示环锚衬砌结构体系预应力荷载传递机理，提出单环锚及多环锚预应力等效荷载表达方法。考虑围岩加卸载屈服状态转变和主应力顺序转换对预应力场的影响，建立联合承载条件下的环锚衬砌结构力学计算模型，并建立环锚衬砌应力状态解析解。项目研究成果可为环锚衬砌结构设计及其工程应用提供理论支撑和参考。