隧道周边应变与挤压因子法在隧道围岩大变形预测中的应用

挤压性大变形是高地应力区软弱围岩隧道施工中亟待解决的工程难题,其变形量的预测是高地应力环境条件下软弱围岩隧道变形控制的关键。基于此,文章在总结前人研究成果的基础上,首先采用挤压因子法对某软岩隧道挤压性大变形等级进行预测,然后采用隧道周边应变法对挤压性大变形的量值进行预测,并提出了针对性控制措施。预测结果与实际开挖后的监控量测值较为吻合。该预测方法可对同类工程施工变形控制提供借鉴和参考意义。     

乌鞘岭特长隧道软弱围岩大变形特性研究

乌鞘岭特长隧道全长20050m,是我国目前正在修建的国内最长的单线铁路隧道.隧道施工中发生了严重的围岩大变形,主要表现为隧道中部岭脊地段F4～F7断层构成的"挤压构造带"在深埋高地应力条件下的软弱围岩大变形,拱顶最大下沉及侧壁最大水平收敛变形量均达1000mm以上,导致初期支护开裂破坏并严重侵入衬砌净空等,不得不将初期支护全部或部分拆除重做,再施作二次衬砌.文章对隧道区域工程地质环境、软弱围岩变形力学特性及初期支护破坏规律、围岩变形的影响因素等进行了分析研究,并讨论了隧道围岩加固、初期支护预留变形量与二次衬砌施作时机等问题.     

隧道大变形施工处治技术

利用国内外已有成果,结合某隧道实体工程,研究分析了软弱围岩隧道大变形施工处治技术,归纳出了其围岩大变形的破坏特征,分析了其大变形产生的原因,提出了合理的施工方法和处治措施,可供软弱围岩隧道施工参考.     

高地应力软弱围岩隧道挤压型变形和可让性支护原理

软弱围岩深埋隧道修建遇到的挤压型围岩大变形问题,是山岭隧道工程中的难题。文章在对挤压型变形机制、判识方法和变形特征进行分析的基础上,介绍了挤压型变形围岩支护的可让性原则,从地层特征曲线和支护-围岩相互作用出发,阐述了可让式支护的原理并给出了相关的设计施工要点。     

隧道软弱围岩变形特征及处治技术研究

文章以广西河池至百色高速公路机场隧道软弱围岩段处治为例,总结分析了隧道软弱围岩变形的特征,提出了针对掌子面挤出变形、拱脚围岩下沉变形、支护结构变形及隧底软弱围岩处治等成套处治技术,成功解决了机场隧道软弱围岩段大变形问题,对后续类似工程问题具有参考意义。     

理念的更新——对软弱围岩隧道工程的思考

文章着眼于矿山法修建的软弱围岩隧道工程,从现代隧道工程理念出发,探讨了隧道开挖引起的围岩力学形态从松弛到离散的变化过程以及针对这种过程的控制技术和超前支护的功能等问题;针对高地应力软弱围岩挤压性大变形的难题,文章着重论述了可让型支护系统作用原理和设计方法。在此基础上,结合工程实际提出了几点看法,供进一步探索、思考和实践。     

浅埋软弱围岩隧道变形特征研究

软弱围岩隧道受开挖扰动影响变形明显,施工中若稍有不慎,就会导致隧道塌方。文章以厦门莲岳隧道A匝道隧道为工程背景,结合隧道所处地质条件,采用数值模拟和现场监测相结合的方法,对浅埋软弱围岩隧道变形特征进行了研究。结果表明,对于软弱围岩隧道,不论是全断面开挖还是台阶法开挖,掌子面挤出位移最大,拱顶下沉和地表沉降次之,洞周收敛最小;隧道围岩变形可以分为掌子面前方的先行变形和掌子面后方变形,围岩条件越差,先行变形越大,约占总变形的10%~30%;采用台阶法等分部开挖工法,可减小对掌子面前方围岩的影响范围及变形。在对浅埋软弱围岩隧道的周边环境有严格变形控制要求时,要采取更为严格的预加固措施来控制隧道施工引起的围岩变形,以确保隧道施工及周边环境的安全。     

对形变压力的认识——隧道围岩挤压性变形问题探讨

在高地应力背景下,隧道开挖造成岩体应力大幅度变化,软弱围岩松弛阶段的变形将达到很大的量级,这就是挤压性大变形的本质所在。国际隧协曾归纳总结的隧道结构设计模型中的"收敛-约束"模型可以十分贴切地说明支护和围岩在松弛变形发展过程中的相互作用。支护在同围岩共同变形中承受的荷载有别于隧道设计规范中规定的由离散岩体重量产生的"离散压力",可以称为"形变压力"。囿于对离散压力荷载的认识,很难找到处治挤压性大变形的合理途径。文章从形变压力的特性出发,对挤压性围岩隧道工程中的若干问题进行探讨,着重论述通过围岩变形的适度释放来缓解形变压力的处治理念以及与之相应的可让型支护和岩体锚固技术。     

乌鞘岭特长隧道F7断层围岩大变形段二次衬砌安全度分析

乌鞘岭特长隧道11#斜井处正洞在穿越F7断层时,由于隧道埋深大、断层岩体破碎、岩体完整性差、围岩自稳能力弱、受挤压影响等,开挖后围岩变形长时间不收敛,50天后的变形仍为2～4 mm/d,累计最大变形量已超过60 cm,部分地段严重侵限,不能满足<铁路隧道设计规范>关于施做二次衬砌的规定.如果二次衬砌及时施做,在软岩大变形条件下其安全度问题值得进一步深讨.文章通过现场量测和监测手段,并结合理论计算与分析,对已施工完毕的二次衬砌段的结构安全度进行了探讨,结果认为,目前乌鞘岭隧道F7断层二次衬砌结构的设计参数是可靠的和安全的,满足<规范>所规定的在软弱围岩地段的要求,建议及时施做二次衬砌.     

雁门关隧道挤压性围岩变形控制技术

北同蒲取直线雁门关隧道软弱围岩段埋深大,构造应力水平高,给隧道施工变形控制造成了极大困难。文章根据雁门关隧道挤压性围岩的工程特性,对洞室变形控制措施进行了研究。首先通过有限差分法(FLAC3D)数值计算确定了弧形导坑预留核心土三台阶七步开挖法的核心土合理长度;其次根据隧道塑性区范围与形状优化了系统锚杆的长度;而后通过对双层支护力学效应及内层支护施作时机的研究,得出理论上雁门关隧道的内层支护最佳时机为内层支护与外层仰拱同时施作;最后通过数值计算和现场工程实践,形成了"3~4 m核心土长度+超前支护+优化设计的系统锚杆及锁脚锚管+双层支护(H175+I22a)"的雁门关隧道挤压性围岩变形综合控制技术。该技术对在构造应力发育的软岩地区修筑隧道具有一定的借鉴意义。     

Controlling Structural Deformation of Surrounding Rock Passed by a Deep-Buried Tunnel北大核心CSCD

Layered rock masses with rapid and serious initial deformation and anisotropy regarding the spatial dis-tribution of the failure are encountered during the construction of many large and deeply buried tunnels on the Lan-zhou-Chongqing railway. It is difficult to deal with the resulting problems with conventional control measures, and additional support measures are frequently needed, which significantly affects construction. Focusing on this special large non-linear deformation, the failure mechanism of the large structural deformation of layered rock masses is thor-oughly analyzed by geological site surveys, laboratory tests, site tests and 3DEC discrete element numerical simula-tion. The research results show that high geostress induces rapid and strong squeezing deformation after excavation in low-strength rock masses, and anisotropy of the layered rock mass controls the stress redistribution after excava-tion and the asymmetrical distribution of tunnel section deformation. Based on the asymmetric deformation mecha-nism of the rock mass, a directional support measure for the disturbance anisotropy of the layered rock mass is pro-posed as a rock mass control to reinforce it in an active way. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Analysis on the Characteristics and Development Trends of the Support Technology of High Ground Stress Tunnels in China北大核心CSCD

Combining the present situation and development trend of different tunnel support technologies at home and abroad, this paper analyzes the problems of rockburst in hard rock tunnels and large deformation in soft rock tunnels caused by high ground stress. It is concluded that: 1) regarding the rockburst problem, the current support technology is mainly influenced by the rock burst mechanism which is dominated by static factors, and so the used support components are generally of smaller deformation performance and "passive support" properties; 2) as the rockburst is the result of dynamic-static stress coupling, and only the anchor bolt has the "active support" attribute in the current "shotcrete+anchor bolt+wire net" support system, so the best support system should have the two functions of active support and energy release in terms of the rockburst problem, and the key focus of the research and development is anchorage members; 3) there are three main support types for large deformation in soft rock tunnels, e.g. the heavy support, layered support and yielding support. Among them, the heavy support system in underground cavern with large deformation is easy to induce excessive surrounding rock pressure, and so the applicable conditions are limited. The layered support system is still not the best choice due to its immature theoretical study, difficult determination of the thickness value and the installation time of each support layer and the interference to construction progress. With the characteristics of timely support and yielding while supporting, the yielding support system can give full play to the performance values of surrounding rocks and supporting materials, and make both of them reach the optimal state, so it is the best choice for supporting the soft rock tunnels with large deformations. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

泥质软岩地层洞室变形分析及对策

文章以兰渝铁路胡家湾隧道进口和东扎沟隧道进口施工为例,阐述在如泥岩、页岩等软岩地层洞室开挖时出现的围岩变形特点;从地质、施工等方面分析其变形原因;并从施工时机、施工方法等施工角度分析,制定控制变形的应对措施。以期在类似地层洞室施工时,在控制围岩变形中起到一定的指导、借鉴作用,并确保工程质量及安全。     

TBM施工深埋隧洞围岩分类方法初探

文章针对TBM施工隧洞的围岩分类问题,分析了西南某水电站深埋隧洞影响洞室稳定性的因素,以<水利水电工程地质勘察规范>中的围岩分类方法(HC分类)为基础,依据岩石单轴抗压强度、岩体的完整性系数、岩体结构为主要因素来探讨适合TBM施工深埋隧洞的围岩分类.     

On Stability Analysis and Classification of Surrounding Rocks in Rock Tunnels北大核心CSCD

After 1975, the appearance of finite element numerical limit method and the application and development of computer technology have brought the elastic-plastic analytical calculation of engineering materials into a new era of numerical limit calculation. The new methods, namely, strength reduction method and load increment method, as well as the recently proposed ultimate strain method, are adopted in the rock tunnels studied in this paper. To solve the uncertainty of mechanical parameters of surrounding rock in rock tunnels and provide more scientific and reasonable mechanical parameters of surrounding rock, the surrounding rock classification must be made combining theory, investigation and experience. Taking the surrounding rock classification in rail transit tunnels as an example, the improvement of the classification level includes improving the strength index, mainly adopting the quantitative classification method, reasonably determining the basic index BQ value of rock mass quality, increasing the number of surrounding rock classifications, formulating the surrounding rock classification tables for the running tunnel and the station tunnel, and achieving the coordination and unification of qualitative and quantitative classification methods. Finally, the quantitative indexes of surrounding rock self-stability are determined, and the more scientific and reasonable physical and mechanical parameters of surrounding rocks are put forward through back calculation. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

木寨岭隧道软岩大变形段支护措施研究

文章结合新建兰渝线木寨岭隧道工程实践,在了解了碳质板岩地层发生大变形的原因和机理的基础上,对高地应力条件下软岩大变形的控制技术进行了分析研究,提出了处理隧道大变形应以控制为主的原则,以及确保隧道安全施工、快速通过的支护措施和变形控制对策。     

木寨岭隧道高地应力软岩大变形施工技术

木寨岭隧道施工中受到高地应力软岩地质的影响,初期支护多处出现大变形,破坏严重。为了保证顺利安全施工,采用了先柔后刚、先放后抗、多重支护、预留变形量、应力释放、提高二次衬砌刚度和超短台阶开挖等措施,有效控制了围岩大变形。文章主要介绍了木寨岭隧道的工程概况、施工中出现的大变形情况,以及控制大变形的各项措施和效果检验。     

超前预加固大断面隧道施工参数系列化研究

论文以武广客运专线浏阳河隧道为工程背景,根据铁路隧道围岩分级和断面尺寸为主要影响因素,提出新的掌子面稳定性分级方法及分级数;对影响大断面隧道掌子面稳定性的影响因素进行序列化及参数敏感性研究,得到超前预加固大断面隧道围岩稳定性影响因素序列及掌子面超前加固参数敏感性;然后在掌子面稳定性分级及超前预加固大断面隧道影响因素序列基础上,提出超前预加固大断面隧道施工参数系列,为浅埋大断面隧道施工提供指导.     

浅谈兰渝铁路隧道四大高风险源及应对措施

兰渝铁路隧线比达68.1%,存在富水未成砂岩、高地应力软岩大变形、瓦斯(天然气)、岩溶(煤矿采空区)突泥突水四大高风险源,严重影响施工安全、进度和投资控制.通过现场调研、专家会诊、施工试验,以及不断地优化设计和施工方法,初步探明了主要影响因素,基本掌握了一定的规律,制定了继续试验性施工的针对措施.目前,兰渝铁路隧道施工总体处于受控状态.文章重点介绍了兰渝铁路隧道的四大高风险的特点及危害,较详细地分析了应对大变形的措施和施工方案.