高地温复杂环境下地下洞室岩体时效力学特性和锚固衬砌机理及其性能演化研究

The ageing mechanical characteristic and stability of rock under high ground temperature have become one of front direction concerned with rock mechanics field. In high temperature underground engineering, coupling effect of rock, high ground temperature, water, environmental load and other factors are leading to rock damage happen and disaster appear, and it has significant impact to underground engineering stability. In order to revealed engineering geological process and ageing mechanical characteristic of rock under high ground temperature, on the basis of field monitoring and meso-mechanical testing, analyze the features of geological structure, fractal character of rock mass discontinuity, fault structure, rupture in strength of underground engineering. The meso-structure of evolution law of rock in underground cavern by using of CT technique, the dissertation mainly studied the ageing properties of mechanical of fractured rock of high ground temperature, analysis the relation between ageing properties of bolted rock mass and macro-mechanical characters under high ground temperature and coupling action in underground cavern, in order to revealed mechanism of anchoring and lining of mechanism of anchoring and lining and mechanic property evolution under high ground temperature in underground cavern. The project analyses the problems in ageing properties of mechanical, the mechanism of anchoring and lining; mechanic property evolution, establishment of finite element method and discrete finite element for the damage of rock and underground engineering stability under high ground temperature in underground cavern, to simulate macroscopic mechanics responses and evolution characteristics of micro structure under complicated load and high ground temperature. Rely on engineering application, the theoretical analysis is verified and technology demonstration in underground cavern under high ground temperature complex environment.

高地温条件下地下洞室岩体的力学特性及稳定性一直是岩石力学领域关注的前沿方向。在高地温地下工程中，由于岩性、高地温、环境荷载等多重因素的耦合作用，导致岩体损伤，对地下工程稳定性产生了重大影响。为揭示高地温复杂环境下地下洞室岩体的工程作用机制与时效力学特性，以现场监测与室内外细观力学试验为基础，对洞室地质构造、岩体结构、断层结构及其岩体破环方式进行分析，采用CT、SEM技术对洞室岩体的细观结构演化规律开展研究，重点研究高地温环境下岩体的时效力学特性，分析高地温-环境荷载耦合作用下锚固岩体的时效力学特性与宏观力学特性之间的关系；揭示高地温复杂环境下岩体锚固衬砌机理及其力学性能演化特征。建立基于扩展有限元法和离散元法的高地温洞室岩体损伤、稳定性演化宏细观数值方法，模拟复杂荷载及高地温条件下岩体的宏观力学响应与细观结构的演化特征。依托具体工程应用，进行高地温复杂环境下地下洞室的验证与示范。

高地温条件下洞室岩体的时效力学特性及其多场耦合效应一直是岩石力学领域关注的前沿方向。在高地温环境中，由于岩性、高温、渗流、环境荷载等多重因素的耦合作用，导致岩体损伤破坏，对洞室围岩稳定产生了严重影响。为揭示高温复杂环境下洞室岩体的工程作用机制与时效力学特性，以高地温洞室现场温度监测数据为基础，研究高地温隧洞在不同围岩类别、不同工况下围岩及其支护结构的温度场变化规律及其演化机制。开展高温岩体细观结构演化及其强度特征试验，采用CT技术对高温热处理后岩体内部的微结构进行了三维重构分析，揭示了洞室岩体受热后微结构的变化规律及其强度演化特征，建立了反映损伤阈值和残余强度特征的高温岩体损伤演化方程及其本构模型，并进行了高温隧洞THMD耦合模拟计算，分析了不同温差、不同线膨胀系数、不同内水压力作用下洞室围岩的承载特性，揭示了高地温隧洞的多场耦合效应，温度梯度、内水压力以及岩体线膨胀系数越大，隧洞围岩的损伤程度越大，探明了高地温梯度水工隧洞承载特性的演化机制。重点考虑深部高温岩体温度-渗流-软化效应，建立了热力耦合作用下围岩应力及塑性软化区、塑性残余区的控制方程，同时考虑围岩的高温软化效应、渗流、支护力及中间主应力系数的影响，推求了围岩塑性软化区、塑性残余区的应力及半径表达式。基于高温岩体显著的温度-渗流-软化效应，围岩塑性残余区和软化区半径分别增加了21.1%和19.4%。结合新疆布仑口-公格尔高地温引水隧洞工程，基于现场锚固结构监测数据，分析不同隔热材料复合支护结构的温度分布规律及时效力学特性，研究高地温条件下锚杆的力学特性和喷层混凝土结构的受力破坏形态，对锚固支护结构体系的荷载传递、应力调整等作用机制进行深入了分析。围岩的初始温度越高，同样温差下温度效应越明显，揭示了高地温复杂环境下洞室岩体锚固支护机理及其力学性能演化特征。研究成果为高地温地下洞室设计、施工及运行管理提供了重要的理论依据。