高岩温隧道支护材料和界面变温养护条件下的力学性能及支护结构计算模型

In the construction of high rock temperature tunnel, construction ventilation takes away some heat, and the temperature inside the tunnel gradually changes with time and space. At the same time the maintenance processes of support materials (concrete, mortar) including setting, hardening etc and various interfaces in the support experience from high temperature to room temperature. The change of temperature causes the deterioration of support materials’ and interfaces’ mechanical properties, and especially in the early stage when temperature gradient is large it is more serious. As a result, if the temperature was not controlled, it would lead to hidden trouble in the safety and durability of the high rock temperature tunnel support. At present, domestic and external study on the high rock temperature tunnel usually adopts isothermal curing method, which does not accord with the fact that the temperature changes during the construction, and so this method has limitations. In this research project, the methods of theoretical analysis, numerical simulation, laboratory test, and engineering verification will be used to find out the variation law of the temperature field with time and space. A new experiment system will be produced which can simulate the variable process of the temperature in high rock temperature tunnel. The mechanical properties’ variation rule of the tunnel support materials and interfaces will be obtained. A structure calculation model of high rock temperature tunnel will be established, which is based on the support materials' and interfaces' mechanical properties under variable temperature condition. The research results can provide theory support for the design of high rock temperature tunnel.

在高岩温隧道建设中，施工通风会带走部分热量，隧道内温度场将随时间和空间逐渐变化，此时，支护材料（混凝土、砂浆）的凝结、硬化等养护过程将经历由高温到常温的变温过程，同时隧道支护结构中各种界面也将经历同样的变温过程。这一变温过程会造成支护材料和界面的力学性能劣化，特别是早期变温梯度大时，影响更严重，可见，如果不加以控制，高岩温隧道支护结构将存在安全和耐久性隐患。目前，国内外在高岩温隧道研究中，一般采用恒温养护方法研究支护材料和界面的力学性能，不符合隧道内温度场随施工进程而变化的客观事实，因此，这类研究具有局限性。本项目运用理论分析、数值模拟、室内试验、工程验证等方法，研究高岩温隧道温度场的时空演变规律，研发可模拟高岩温隧道变温过程的试验系统，研究变温养护条件下隧道支护材料及界面的力学性能变化规律，建立基于变温养护下支护材料及界面力学性能的高岩温隧道计算模型，为高岩温隧道设计提供理论支持。

当隧道埋深较大或穿越导热断层时，围岩温度会显著升高，这类隧道被称为高岩温隧道；为了保障高岩温隧道内正常施工作业环境，要采取持续降温措施，此时，隧道支护及支护结构界面要经历从高温到常温的变温过程，从而引起其力学性质劣化，承载力下降、耐久性降低。为此，本项目采用现场测试、室内试验、理论分析及数值模拟等综合方法，开展了高岩温隧道支护材料力学性能、支护结构界面剪切滑移特性及支护结构计算模型研究。首先，建立了高岩温隧道一维非稳态导热方程，探明了高岩温隧道开挖后温度场的时空演变规律，提出了围岩-支护结构温度场理论预测方法，结合现场测试和室内模型试验成果，提出了高岩温隧道支护及其界面的高温变温养护方法；其次，基于该变温养护方法，开展了锚杆砂浆、喷射混凝土和模筑混凝土等支护材料的力学试验和SEM试验，分析了温湿度对支护材料力学性能的影响规律，探明了支护材料高温变温养护后的细观结构及劣化机理，基于多元回归方法，建立了不同温湿度养护条件下的支护材料强度预测模型；开展了高温变温养护条件下喷射混凝土-围岩、型钢-混凝土、锚杆-砂浆-围岩等界面的剪切滑移试验和CT扫描试验，分析了不同温湿度条件下的界面强度变化规律，探明了不同界面破坏形态，基于随机损伤力学理论，建立了高温损伤的围岩-喷射混凝土界面、型钢-混凝土界面、锚杆-砂浆-围岩界面的粘结滑移本构模型；最后，基于上述高岩温隧道支护材料的强度特性及界面滑移本构模型，采用热-应力耦合方法，研究了支护结构受力特性，据此建立了高岩温隧道支护结构计算模型，并通过现场试验验证，成功应用于典型高岩温隧道工程中，指导了重大隧道工程建设。本项目成果阐明了高岩温隧道温度场演变规律、支护材料及其界面力学性质劣化规律，提出了完整实用的高岩温隧道支护结构计算模型，丰富了高岩温隧道支护理论，为高岩温隧道设计和施工提供了有力支撑！