石膏质岩隧道衬砌结构可靠度时变机理研究

The softening, expansion, and corrosion characteristics of gypsum rock are significantly time dependent, which leads to the stability of the tunnels through these rocks deteriorate as the time passed. The typical disadvantages of these tunnels are frequently failure, high maintenance quantity and cost. In this project, the understanding of time-varying mechanism of reliability of gypsum rock tunnel structure is the major target. The softening and expansion characteristics of gypsum rock are investigated, and the softening model and the extended constitutive model considering time effect will be established. The time-varying pattern of external load effect on the gypsum tunnel structure will be revealed. The corrosion mechanism of gypsum rock is studied by using stress-chemical coupling experimental device. A corrosion equation will be established to reveal the time-varying law of the resistance decrease of gypsum tunnel lining. The project also includes the research of catastrophic model of gypsum rock tunnel lining structure and the establishment of its time-varying reliability model; finally, based on the theory of time-varying reliability, the methodology of predicting the health state of gypsum rock tunnel will be presented. The results of the project will provide the necessary basic theories, technical support and decision-making references for the safety of the construction and operation of the corrosion surrounding rock tunnels, reduce the damage of the tunnel lining structure and improve the overall efficiency of the tunnel project.

石膏质岩的软化、膨胀及腐蚀具有显著的时间效应，导致此类地层中的隧道衬砌结构可靠度逐渐下降，严重影响隧道长期健康状态，表现为衬砌结构病害频发、维护量大、维护费用高。对此，本项目针对“石膏质岩隧道衬砌结构可靠度的时变机理”这一核心问题展开研究。研究石膏质岩软化、膨胀特性，建立其软化模型和含时间效应的膨胀本构模型，揭示石膏质岩隧道衬砌结构外部荷载效应的时变规律；研制应力-化学耦合实验装置，研究石膏质岩对隧道衬砌结构的腐蚀机理，并建立腐蚀方程，揭示石膏质岩隧道衬砌结构抗力劣化效应的时变规律；探究石膏质岩隧道衬砌结构的灾变模式，构建隧道衬砌结构功能函数，进而建立衬砌结构时变可靠度模型；最后基于时变可靠理论，提出石膏质岩隧道衬砌结构健康状态预测方法。项目成果集成推广，将为保障我国膨胀腐蚀类围岩隧道施工安全、减少隧道衬砌结构病害、提高隧道工程的整体效益提供必要的基础理论、技术支撑和决策参考。

为满足各地区经济增长的需求，隧道工程建设得到快速发展。由于在膨胀腐蚀类围岩对隧道衬砌结构不利影响研究方面，研究深度和系统性不够，导致隧道衬砌结构病害突出。因此急需解决“石膏质岩软化、膨胀对隧道衬砌结构的共同作用效应”、“应力-化学耦合作用下隧道衬砌结构抗力劣化的时变规律”和“石膏质岩隧道衬砌结构健康状态的准确预测”等问题，为保障我国膨胀腐蚀类围岩隧道施工安全、减少隧道衬砌结构病害、提高隧道工程的整体效益提供必要的基础理论、技术支撑和决策参考。.项目主要研究内容有：.1.石膏质岩隧道衬砌结构外部荷载效应时变机理.2.石膏质岩隧道衬砌结构抗力劣化时变机理 .3.石膏质岩隧道衬砌结构的灾变模式及时变可靠度模型 .4.基于时变可靠理论的石膏质岩隧道衬砌结构健康状态预测方法 .项目的主要成果及意义：.1.揭示了围岩与衬砌材料的时变机理，获得了围岩与衬砌材料力学性能的时变规律，建立了围岩与衬砌结构的时变演化模型。.2.考虑围岩荷载变化及衬砌材料性能劣化双重作用，建立了隧道衬砌结构的时变可靠度模型，实现了隧道衬砌结构时变可靠度的定量计算。.3.首次提出了隧道全寿命周期动态数值模拟方法，能够获得围岩和衬砌结构各时间点的变形与受力情况，以及衬砌结构各时间节点的可靠度。.4.发明了基于大数据的目标可靠度评估方法，提出了基于目标可靠度的隧道全寿命周期灾害控制及设计、施工和养护的动态优化技术；解决了隧道全寿命周期灾害控制及设计施工优化问题，达到了从设计施工阶段控制隧道病害和降低养护成本的效果。