深部隧道围岩分层断裂机理及其主次承载拱构建技术

A variaty of supernormal response characteristic presented by tunnel surrounding rock mass in deep strata put forward a lot of issues which need to be researched urgently. The issue aimed at openning out a mechanism for layered rupture for tunnel surrounding rock mass in deep strata and establishing its corresponding support method. A variety of deep strata models based on rock mass structural types were built in large-scale underground structure laboratory and local unloded device which simulate a tunnel diging was fixed in the deep strata model. A locating technique with acoustic emission and figer & grating sensoring technique were used to survey an overall course for occurrence, propagation, regression and cessation of the layered rupture for surrounding rock mass resulted from diging. Analytical formulae expressing geometrical and mechanical distributing configuration of layered ruptue surrounding rock mass were deducted based on model test data and established the deep rock mass mechanical analysis method regarding damage, catastrophe, and fracture. Mechanical mechanism for layered rupture for surrounding rock mass was opened out. A performance module was developped based on mechanism for layered rupture for surrounding rock mass and the module was embedded the FLAC software to alter and extend its performance. A numerical simulation equipment on digging of tunnel in deep strata was established. United support principle, design method and construction technology for crucial & subsidiary bearing load arch were presented based on geometrical distributing configuration of ruptue zone for surrounding rock mass and the numerical simulation equipment. The researched results in the issue resolved some problems regarding layered rupture surrounding rock mass and its correlative disaster can be hold back in the deep tunnel effectively. A reference to point out mechanical mechanism for various supernormal rupture phenomena of surrounding rock mass was afforded.

深部隧道围岩呈现的许多超常响应现象，提出了大量迫切需要研究的新课题。本项目以揭示其中围岩分层断裂现象产生机理并构建相应支护方法为目的。在大型地下结构试验平台上建造基于岩体结构的深部地层模型并在其内部安装模拟隧道开挖的局部卸载装置。采用声发射检测定位与光纤光栅传感技术联合监测开挖导致的围岩分层断裂发生、扩展及停止的全过程。通过建立深部岩体力学的损伤突变破断分析方法，结合试验结果，导出表征分层断裂围岩分布形态、力学状态特征的解析公式，揭示围岩分层断裂现象的形成机理。研制基于分层断裂机理的数值功能模块，将该模块植入FLAC软件核心机构，改造并扩充其功能，构建深部隧道开挖数值模拟工具。基于断裂圈分布形态机制，利用数值模拟工具，提出主、次承载拱联合支护原理、设计方法及其构建技术。本项目将解决围岩分层断裂的有关问题，有效遏止深部隧道工程的相关灾害，为深部地下工程围岩各种超常破裂现象机理研究提拱借鉴。

随着社会发展的需要，人们越来越需要在深部地层中开拓各种工程。由于深部区域存在高地应力、高地温及高水压，工程围岩对开挖的响应及破裂与常规埋深的岩石地下工程围岩存在差异，如分层或分区破裂现象。本项目在开发两套获得发明专利的专用试验装置的基础上，通过系列的室内模型试验、数值模拟计算及理论推演，对深部隧道围岩分层断裂机制及支护技术进行了深入探讨。揭示了深部地层因素（包括岩体的峰后力学性质、热力学特征、地温，等）和支护因素（包括锚杆锚固长度，间排距，预紧力及注浆）对分层断裂启动、断裂层数目、断裂层厚度、断裂层间隔、断裂层与完整层中应力与应变的影响机制。得出在一定的原始应力场中，围岩峰后临界塑性剪切应变值的大小对分层断裂的出现起到关键性作用。将隧道工程岩体分级稳定性判据与强度折减法结合起来，通过模拟试验确定了不同级别岩层中隧道围岩变形与等效载荷变化（强度折减）的关系曲线。利用收敛变形速率特征与围岩状态（连续或断裂）之间的内在联系，建立了判断围岩失效的突变分析模型，提出了隧道围岩自稳能力的表征指标及确定方法。在试验观察的基础上，按照整体状结构岩体，块状结构岩体和板桩结构岩体对于隧道开挖卸载的响应变形及屈服特征，将深部地层岩体概化归纳为Hoek-Brwon材料介质和Duncan-Fama介质。在导出Hoek-Brwon和Duncan-Fama材料岩体介质中各种非规则断面隧道等效纵向变形曲线，等效地层特征曲线及各种组合支护结构特性曲线建立方法的基础上，提出了以锚杆、喷射混凝土及钢拱架等构件为支护单元的初期支护结构系统稳定程度的安全系数设计计算方法及非确定性分析方法。以研制的承压岩溶水深部隧道施工工艺及锚注一体化的分段锚固式锚杆等专利技术为基础，开发了分层断裂围岩的深部隧道工程承载拱构建技术。本项目的研究成果，在某种程度上为围岩出现分层断裂现象的深部隧道工程的稳定性分析提供了可供选用的方法及相应支护加固技术。