兰州大学机构库 >土木工程与力学学院
分岔隧道围岩损伤与稳定性研究
Alternative TitleStudy on Damage Mechanics and Stability of the Surround Rock Mass of Branched Tunnel
林传年
Thesis Advisor朱元林
2004-04-20
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword分岔式隧道 节理岩体 损伤门槛值 本构方程 弹塑性损伤有限元 围岩稳定性 模型试验 现场监测
Abstract

高速公路分岔式隧道由四车道大拱隧道、连拱隧道、小间距隧道及标准间距的分离隧道组成,它同时具备这些隧道的特点,但是绝对不是这些隧道的简单叠加。高速公路分岔式隧道是在地形地质条件极端复杂、桥隧相连的峡谷山区为了降低工程造价减小施工难度而发展出来的一种新型隧道结构型式。作为一种新型隧道形式,目前国内外对分岔式隧道的设计施工尚未见全面系统的研究,国内外尚无相应的设计、施工技术规范和标准。其受力特点、围岩稳定性分析、设计施工方法等尚处于经验积累阶段,因此,开展分岔式隧道的围岩稳定与损伤特性研究具有十分重要的理论和实际意义。
本文以八字岭分岔隧道中断续节理岩体为研究背景,针对分岔式隧道的特点,首先开展了室内类岩石材料损伤力学特性实验,重点在于研究节理裂隙岩体损伤破坏特性;在此基础上,开展相应的损伤理论研究,即应用不可逆热力学原理,建立裂隙岩体弹塑性损伤本构方程和损伤演化方程,为进一步分析分岔式隧道合理间距及围岩稳定性建立数值分析模型;通过分岔式隧道大型力学模型实验,建立分岔式隧道合理间距和损伤破坏机理,为大拱与连拱过渡地段、连拱与小间距过渡地段提供复杂受力条件下的破坏形态和损伤演化特性分析;通过理论分析和模型实验确定的分岔式隧道合理间距,进一步通过现场监测来验证合理性,因此进行了分岔式隧道现场监控量测与反演分析,为分岔式隧道合理施工提供安全和信息保证;利用上述研究成果,综合进行分岔式隧道围岩损伤与稳定性分析,最终解决分岔式隧道设计和施工中的关键问题。
本论文针对八字岭隧道节理岩体的特点,首先开展了节理岩体损伤特性的力学实验,通过试验研究了类岩石材料的配比,提出了新的模型实验材料,为开展节理岩体损伤实验提供条件。利用声发射检测手段,通过对含裂纹类岩石材料试件的单轴压缩试验,测定了含裂纹体准脆性类岩石材料受压破坏过程中裂纹扩展区域内的声发射全过程曲线、 声发射分布及声源点的分布状态。开展了完整试件、含单裂隙初始损伤和双裂隙初始损伤试件的单轴压缩实验,得到了全应力应变曲线。
通过声发射累计数和损伤变量的关系,首次定量地确定了类岩石材料损伤破坏各个阶段的临界值。通过定量确定的损伤临界值,首次提出了节理岩体破坏的五个阶段:初始裂纹闭合阶段;线弹性损伤阶段;弹塑性损伤阶段:裂纹生成、宏观裂纹稳定扩展和不稳定扩展;损伤引起材料的破坏和材料的软化行为阶段。定量地分析了完整试件、含单个裂纹初始损伤试件和含双个裂纹初始损伤试件的类岩石材料破坏各个阶段的损伤临界值。针对损伤特性的力学试验,首次用几何损伤的方法,详细地描述了含初始损伤的类岩石材料的破坏机理和全应力应变曲线发生过程,为下一步建立节理岩体能量耗散的损伤本构方程建立实验基础和理论背景。
常规的弹塑性有限元模型由于没有考虑到损伤和塑性的耦合作用,难以模拟破坏时由于内部损伤的累积导致的岩体破坏过程,不能很好地反映实际结构的细观破坏机理。作者采用一种宏细观结合的思路,基于宏细观结合的损伤力学开展了节理岩体能量耗散损伤本构方程的研究,并建立了相应的数值分析方法,为合理评价分岔式隧道围岩稳定和合理间距提供了有效手段。
在理论研究的基础上,本文首次开展了分岔式隧道大规模的地质力学模型试验研究,为隧道围岩损伤特性及稳定性分析提供了试验基础。模型试验中开发的新型相似材料、三维模型系统、开挖监控和数据分析等具有创新性。
在模型试验基础上,针对八字岭分岔式隧道的特点,首次全面开展了分岔式隧道各个阶段的现场监控量测及反演分析研究。给出了分岔式隧道监控量测系统的设计方法;在对围岩变形、松动范围、支护内力和中隔墙压力及其二次衬砌压力等进行全方位跟踪监测的基础上,分析了分岔式隧道围岩和支护系统的变形和受力特点;根据现场监控量测结果开展了基于人工神经网络的反分析研究。
最后,在室内损伤试验研究、数值分析研究、大型模型试验和现场监控量测的基础上,通过建立的弹塑性损伤耦合有限元方法开展八字岭分岔式隧道围岩损伤特性及合理间距研究,为类似工程提供经验及分析方法。通过对计算结果的对比分析,也说明了本文方法在处理节理裂隙岩体问题时的适用性和有效性。

Other Abstract

The highway branched tunnel is one kind of new tunnel structure pattern.It is being exploited in order to reduce the project construction cost and construction difficulty in the area which the terrain and geology condition are complicated while the bridge connected the tunnels,especially in canyon mountainous area. The highway branched tunnel is composed commonly of four-lanes big span tunnel, multi-arch tunnel,small spacing tunnels and standard spacing separation tunnels.Researches on the design methods,construction techniques,damage mechanics and stability of the surround rock mass of the highway branched tunnel are nearly blank currently as it’s new.Therefore, it is in urgent need of studying on damage mechanics and stability of the surround rock mass for branched tunnel when the branched tunnel structure used first in Bazilingsupper long tunnel in Yichang-Enshi expressway.
Hence the mainly characteristics of the branched tunnels can be studied in the thesis.The discontinuous jointed rock mass in Baziling branched tunnels are considered as the studying background. The mechanics test about the damage mechanics property of jointed rock mass is carried on. Upon such tests, corresponding damage analysis in theory is developed. Applying principle of irreversible thermodynamics theory,elasto-plastic damage constitutive equations and damage evolution equations of fractured rock mass is developed which are the theory basic of next analyses step--reasonable spacing of the branched tunnels and stability of surrounding rock mass; Onthe foundations of theory analyses, through modeling test of the branched tunnel,reasonable spacing and damage failure mechanism of the branched tunnel is developed,which provides failure configurations and damage evolution property of transition section under complex stress condition where large arch to double arch and double arch to small interval tunnels; reasonable interval that are determinated by theory analyses and modeling test must be validated by in-situ measurement, so in-situ measurement technique and back analysis method for the branched tunnels are introduced, which ensure the safety and information for the construction; Applied above researched results,built the theory analysis method and rational construction procedure of preserving rock pillar in the branched tunnels; Key issues in tunnel design and construction are finally solved through above research and in-situ measurement analysis.
Aiming at the property of jointed rock mass in Baziling branched tunnels,mechanics test of the damage of the jointed rockmass is carried on at firstly, and proportioning of rock-like materials is studied, provided new modeling experiment materials, which provide essential conditions for similar test of jointed rock mass. By AE (Acoustic Emission) monitoring and uniaxial compress test of mortar specimen with cracks, AE full process curve of compress failure process in crack propagation region of brittle material with cracks, as well as distribution of AE and sound source points, is menstruated. Full rock specimen, and uniaxial compress experiment of specimen with initial damage and that with double-crack initial damage are imposed, and full stress-strain curve is gained.
By the relationship between AE accumulative number and damage variable, for the first time critical thresholds for each phases of damage and breakage of jointed rock mass are quantificational determined. Five phases of jointed rock mass breakage are first brought forward: initial cracks close phase; linear elastic damage phase;elasto-plastic damage phase; cracks create and macroscopically cracks stably expand and unstably expand phase; material failure and softening phase caused by damage.
Full specimens and critical theshold for each phases of material failure of single initial crack and double initial cracks specimen are quantificational analyzed, which are the experimental foundations for determinations least space of the branched tunnels.
Aiming at mechanics test of the damage characteristic, with geometry damage method imposed for the first time, failure mechanism of rock-like materials with initial damage and occurring process of full stress-strain curve are amply described, which provide experimental foundations and theory background for next step that constructs damage constitutive equation of energy dissipation of jointed rock mass. Here damage constitutive equations of the energy dissipation of jointed rock mass are studied, and corresponding numerical analysis method is developed, which provides effective instrument for rationally evaluating stability of surrounding rock mass and reasonable interval of the branched tunnels.
Based on the theory study, such large-scale geological mechanics experiment is for the first time carried on, providing experiment foundations for damage characteristic and stability of surrounding rock mass of the Baziling branched tunnels.
On the basic of modeling experiment, aiming at the characteristics of the Baziling branched tunnels, for the first time in-situ monitoring and measurement as well as back analysis research of each phases of the tunnel, and design method of tunnel in-situ monitoring and measurement system is introduced; By omnidirectional tracing monitoring on surrounding deformation, loosening area, supporting internal force,partition wall and lining stress, deformation and force characteristic of surrounding rock mass and supporting system is analyzed; Based on the monitoring result, back analysis of tunnel stability is developed.
For the sake of the better evaluating surrounding damage characteristics and reasonable interval of the Baziling branched tunnels, based on the above researches and experiments, the finite element method for elasto-plastic damage is developed to provide experience and analysis method for the similar engineering.

The finite element method of coupling elasto-plastic with damage is introduced.damage characteristic of the surrounding rockmass and reasonable interval of the branched tunnels are simulated. By comparing the result of FLAC3D with that of DFEM and that of modeling experiment, the method introduced here is proved correct and effective for the jointed rock mass.

URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226533
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
林传年. 分岔隧道围岩损伤与稳定性研究[D]. 兰州. 兰州大学,2004.
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