超大断面黄土公路隧道围岩压力计算方法分析

文章基于唐家塬超大断面黄土隧道工程实例,采用常用的五种围岩压力计算方法分别计算了围岩压力,并与实测值进行了对比分析,得出了现场实测垂直压力与太沙基理论计算结果基本吻合的结论。在此基础上提出了太沙基理论侧压力系数修正方法,并推荐采用修正后的太沙基理论作为唐家塬隧道的围岩压力计算方法。针对现有隧道深、浅埋界定标准的问题,提出了以中心线土体侧压力系数变化规律为依据的深、浅埋界定数值模拟方法。由此认为,唐家塬隧道为浅埋隧道,隧道深浅埋界限为90 m。     

龙潭湾大跨径隧道断面形状优化设计研究

目前三车道隧道断面形状设计没有统一的标准,合理的断面形状设计既可节约成本,又可保证隧道的安全性.文章以龙潭湾隧道为工程背景,利用ANSYS有限元软件对不同扁平率的断面隧道开挖后的应力分布、位移分布、衬砌受力等进行了数值模拟分析;运用层次分析法对影响隧道安全性与经济性的最大正应力、拱顶下沉、开挖面积、衬砌周长等日标值进行了多目标优化,提出了依托工程条件下的最优化断面形状.     

地表建筑对下穿隧道的安全性影响分析研究

采用ANSYS有限元软件对新宝塔山隧道的浅埋段地表建筑施工对下穿隧道的影响进行模拟分析,得到不同间距及不同埋深情况下地表建筑对下穿隧道的应力及衬砌安全性的分析结果。分析得出:住宅楼桩基外缘距离既有隧道边墙为4 m时,铁路隧道受到影响较大;当间距调整为8 m时,楼房施工后引起隧道衬砌结构位移较小,隧道结构安全度均满足规范要求。由此,建议按照间距为8 m的方案实施,覆土回填3 m时,计算结果显示隧道仍然是安全的,其覆土回填厚度可以按照规划设计的地面高程1 009 m考虑(最大覆土回填3m、埋深10.7 m)。     

再谈隧道衬砌水压力

文章从地下水资源保护和衬砌结构安全度出发,分别针对浅埋矿山法城市隧道和高水头地下水水头山岭隧道对衬砌水压力问题进行了讨论,并对地下水处治原则和设计要点提出了若干建议.     

层状土地层中浅埋隧道施工性态的模拟与分析

文章应用非线性弹塑性模型,对层状土地层中浅埋隧道全断面开挖过程进行了三维有限元分析.模拟了开挖面空间效应,获得了距开挖面不同距离处的位移释放系数.并利用"虚拟支撑力"法进行了隧道开挖卸荷的有限元模拟计算,确定了衬砌的合理安装位置,说明了层状土浅埋隧道开挖中利用开挖面空间效应的必要性.     

降雨入渗对浅埋偏压隧道及其支护系统的影响

利用渗流-应力耦合方法对浅埋偏压隧道在降雨入渗情况下的稳定性做了三维数值分析.模拟了隧道的开挖、锚杆支护和衬砌支护过程,以及完工后长期降雨对隧道及其支护系统的影响.锚杆使用杆单元模拟,采用杆单元埋入实体单元技术,简化了有限元建模过程.计算模型对隧道有无排水系统的情况作了仔细分析,结果表明,在不排水条件下,降雨入渗将使隧道衬砌的最大弯矩增加近1倍,锚杆上的最大轴力增加近20%;而在排水条件下,衬砌和锚杆上的力学行为和降雨前相比,并无明显变化.因此,隧道排水系统的合理设置,对于降雨期间的隧道稳定性和支护系统的力学行为有重要影响.     

隧道围岩压力和锚杆轴力的特性分析

结合江西武吉高速公路隧道15个典型断面的监测信息.分析围岩压力和锚杆轴力的稳定值和稳定时间变化规律.结果表明,锚杆未能充分发挥支护作用,应加强锚杆锚固力;隧道位置、施工方法及围岩级别对围岩压力和锚杆轴力的稳定时间有影响.利用围岩压力经验公式计算值与实际监测值进行比较,分析了经验公式对实际隧道工程的适用性.结果表明,深浅埋法计算值比实测值大;系数法和普氏法计算值与实测值相近,但计算结果有赖于参数的选取;泰沙基法计算深埋隧道的围岩压力误差较大.考虑隧道埋深和围岩级别的影响,获得围岩压力与隧道埋深的乘幂关系,以及围岩压力与围岩级别的指数拟合公式.通过监测数据获得的一些规律性结论,可为隧道结构设计和结构计算提供参考.     

新建隧道开挖对既有偏压隧道的影响研究

新建隧道邻近既有隧道施工可能会引起既有隧道结构的较大变形,甚至造成重大事故,这在邻近隧道是浅埋偏压隧道时风险更大。文章依托广西某新建公路隧道的实际情况,使用数值模拟方法计算其开挖对既有隧道应力和变形的影响。结果表明：沿既有隧道纵向,变形最大位置出现在起始开挖断面;沿既有隧道横向,应力变形在断面上反对称分布,变形和应力的最大位置在右侧拱脚处,需加强相应防护监控措施。     

深圳地铁大～科区间大跨度渡线施工技术

为满足后期运营需要,深圳地铁大～科区间隧道设置了一处渡线和一处2号线预留接口段,该段结构复杂,断面形式多样,最大跨度19.9 m,且横穿深南大道煤气管.文章采用工程类比法和理论分析等方法,重点阐述了浅埋暗挖隧道在不同地质及不同断面形式和结构形式条件下采用的超前预加固方案、开挖与支护方法、二次衬砌方案优化等技术,并介绍了对重点部位采用的关键技术,对城市地铁浅埋暗挖施工工艺的推广应用有一定的借鉴价值.     

岩质隧道深浅埋划分方法及判别标准探讨

传统的深埋与浅埋隧道划分方法以普氏压力拱理论为基础,由于普氏理论的局限性,这种划分方法不尽合理。鉴于此,文章将有限元极限分析法应用于隧道深浅埋划分中,提出了隧道深浅埋划分的三条原则。对于Ⅳ级、Ⅴ级围岩的岩质隧道,根据隧道的破坏模式划分深埋与浅埋,破裂面贯通至地表即为浅埋隧道,破裂面没有贯通至地表即为深埋隧道,并利用有限元强度折减法求出浅埋隧道压力拱高度,以此作为深浅埋分界线;对于围岩等级高的岩质隧道,以无衬砌隧道稳定安全系数来划分深浅埋,安全系数大于等于1.5时为深埋隧道,安全系数小于1.5时还要根据破坏模式进行深浅埋判断。此外,深浅埋隧道划分还应考虑环境、施工、地质构造、不稳定块体等因素的影响,由此可能造成围岩整体塌落,形成松散压力。最后,文章建议对于深埋隧道可按弹塑性数值分析计算,而对浅埋隧道除按弹塑性数值分析外,还需按浅埋松散荷载依据荷载-结构模式分析,以确保安全。     

海底隧道涌水量的预测及其应用研究

文章采用理论分析方法,推导了均质围岩中海底隧道注浆圈外表面、衬砌外水压力及涌水量的理论解析公式,并分析了涌水量与各量值之间的关系。通过对地下水渗流场数学模型研究,采用等效连续介质模型用数值方法分析了隧道渗流场的分布,计算出海底隧道的每延米涌水量,并与理论解析解进行了对比分析。结果表明,海底隧道的涌水量不仅与围岩和注浆圈的渗透系数的比值关系密切,而且还与隧道的半径、远场水压力、注浆圈的半径有关;数值计算所得结果与理论解析公式计算得到的涌水量基本一致;为了确保海底隧道施工及运营的安全,应采取"以堵为主,限量排放"的治水方案。     

The Concept and Practice of Treatment for Damage in Railway Tunnel Linings Caused by High-pressure Karst Water北大核心CSCD

In recent years, railway tunnels in karst areas have frequently suffered flooding after high-intensity rainfall, which seriously affects the safety of tunnel operation and the order of transportation, and even interrupts the traffic. Based on the water hazard case in the Yuanbaoshan Tunnel on the Zhijin-Bijie Railway Line, this paper explores the causes of lining damage in terms of geology, rainfall, and the design and construction of water hazard sections, and puts forward the treatment technology for tunnel water hazards with the core concept of "making full use of existing structures and employing open drainage methods in key sections". Besides, this paper simulates and analyzes the formation of hazards and the treatment effect through numerical simulation. The results show that the subjective causes for the damage in tunnel linings include an insufficient understanding of the water-bearing formations at the geological investigation stage, the underestimation of water hazard risks posed by high-intensity rainfall during construction, and the unimproved waterproof and drainage system in the design alteration, while the objective reasons include the development of karst near the tunnel section that passes through the stratum, the strong connectivity of water conduits, and the high-intensity rainfall in a certain period of time on the tunnel site. As for the simulation results, they show that the increase of external water pressure caused by the sudden rise in groundwater level after rainstorm significantly increases the internal force of linings, and eventually leads to a much lower safety factor of sidewall linings and large scale damage, which is in consistency with the characteristics of the actual on-site damage. After on-site emergency treatment, the tunnel structure has become stable and even encountering unprecedentedly heavy rainfall twice, the tunnel has still remained in a good condition. Since then, no water hazards and other disasters have occurred, which proves that the treatment plan is valid. © 2022, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

Experimental and Numerical Study on the Behaviors of Deep-Buried Water-Storage and Drainage Shield Tunnels北大核心CSCD

Deep-buried water-storage and drainage shield tunnels, which are different from road and subway shield tunnels in terms of computation theory, construction technology and operation maintenance, would bear high inner water pressure and large earth pressure. In view of the change of the bearing mode for the lining structure of water-storage and drainage shield tunnels, a full-ring test and numerical analysis are carried out to study the influence of inner water pressure, staggered joint assembly and bolt installation types on the behaviors of water-storage and drainage shield tunnels. The results show that the deformation of the straight-jointed water-storage and drainage shield tunnel varies greatly from the state of empty water to that of full water; and the vertical and horizontal convergence deformations of the tunnel with inner water pressure of 0.6 MPa are 2.2 times and 3.2 times of that without inner water pressure, respectively. The convergence deformation, and the maximum joint opening and bolt tension of stagger-jointed lining structure decrease by 15%-25% and 25%- 40%, respectively, compared with that of the straight-jointed water-storage and drainage shield tunnel. The bolts at the segmental joints will yield because of the increase of inner water pressure and the first occurrence of bolt yield phenomenon is located near the position on the lining structure which is under the action of maximum negative bending moment; because the failure of shield tunnel is always caused by the yield of joint bolts, this position is the weak point for the deep-buried water-storage and drainage shield tunnel. For the water-storage and drainage shield tunnel based on the connection with double rows of bolts, the bolts near the outer arc surface of segmental joints in the area of 90 degree in the vault and arch bottom can be removed; the bolts near the inner arc surface of the segmental joints within the 90 degree of the haunch must be installed, otherwise, the tensile force of the bolts at the segmental joint near the maximum negative bending moment will increase by 5%-14%. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

武汉长江隧道盾构段结构型式研究

武汉长江隧道是我国在高水压、强透水地层中修建的第一条大直径盾构隧道,且左侧河床历年冲淤变化幅度较大,如何选择合理的隧道结构型式是工程设计必须考虑的关键问题.为此,在国内外现有单层管片衬砌和全环双层衬砌的基础上,研究提出了一种新型的“管片衬砌+非封闭内衬”的双层衬砌结构该结构在不增加隧道开挖直径的前提下,允分利用圆形隧道底部和两侧的富余空间现浇钢筋混凝土,并与车道板结构共同组成非封闭二次衬砌结构,可以大幅度地减少河床冲淤变化时的结构横向变形,并确保隧道底部与两侧这些重点部位的防水性能及结构长期稳定性,是一种值得推荐的创新结构方案.     

利用涌水的公路隧道消防供水系统

隧道涌水是施工、运营中引人关注的问题,文章以福建漳诏高速公路鼓志山隧道为例,介绍了利用隧道涌水取代深井系统取水、以高位水池重力流取代全自动加压供水的消防供水系统。     

Study on Designed Water Pressure Limit on Secondary Lining for Single-Track Railway Tunnels with High Water Pressure北大核心CSCD

With the rapid development of China high speed railway, there is a dramatic increase of deep-buried and long mountain tunnels, and more and more tunnels are disturbed by high water pressure during construction and operation. Design for tunnel lining with high water pressure is one of the central concerns in the field of tunnel engi-neering, and the key problem is to forecast water pressure on the secondary lining and determination of water pressure resistance grade. The upper limit of water pressure on the secondary lining is studied by investigation and analysis in this paper. The study shows: (1) There should be an upper limit for the grade of water pressure resistance; (2) It is not very effective to improve the tunnel structure bearing capacity by only increasing the lining thickness haphazard-ly, and the appropriate maximum thickness of secondary lining is 1 m; (3) It is also unsatisfactory to improve the tunnel structure bearing capacity by simply increase concrete strength grade. The appropriate concrete grade is between C40 and C50. (4) In view of tunnel structure safety and good operation performance, the upper limit of water pressure resist grade should be no more than 1.2 MPa. When water pressure on the secondary exceeds the designed value,comprehensive measures should be taken to adjust the value to the appropriate range. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved.     

高水压富水山岭隧道设计浅谈及工程实例

通过对地下水渗流场的理论分析,结合宜万线齐岳山隧道高水压富水地段现场具体处理情况,得出高水压富水隧道设计应注意的主要原则:"以堵为主,限量排放"是高水位富水隧道设计应遵循的基本原则,限量标准应根据隧道区域内具体情况类比确定;地层注浆是实现限量排放的主要方式,确定注浆加固圈范围时应确保注浆帷幕体自身的稳定;排水系统是衬砌结构设计中不可缺少的一部分,在完善可靠的排水系统下,衬砌结构承受的外水荷载能较大幅度地进行折减。     

公路隧道二次衬砌纵向裂缝非线性数值模拟研究

已建隧道普遍存在衬砌开裂现象,裂缝的存在会降低隧道衬砌的承载能力.文章为研究带裂缝隧道衬砌的力学性能,提出了塑性地压、松弛土压、偏压等三种受力裂缝数值模拟的荷载施加模式;分析了几种常见裂缝模型的原理及适用性,并且基于钢筋混凝土有限元非线性分析理论,利用分布裂缝模型进行不同荷载模式下隧道二次衬砌开裂至破坏的全过程分析;通过计算得出了不同加载方式下裂缝的发展及分布规律.研究结果可为隧道衬砌裂缝成因判断及二次衬砌加固改造提供理论支撑.     

武汉地铁越江盾构隧道纵向不均匀变形及力学特性研究

地铁盾构隧道,尤其是大型跨江海的水下地铁盾构隧道,局部埋深通常要大于普通地铁盾构隧道,而且要承受较高的水压力作用;盾构隧道作为特长线性结构,其纵向刚度较小,对于外部荷载的变化较为敏感,由此产生的不均匀变形是隧道工程中不可忽视的问题。文章针对武汉地铁越长江盾构隧道工程,通过三维数值计算探讨了埋深变化、水压变化、地层变化及穿越刚性结构物等因素对越江盾构隧道纵向不均匀变形及受力状态的影响。     

隧道衬砌施工缝蝶形可排水止水带研制

文章分析了隧道衬砌施工缝渗漏水产生的原因,在可排水中埋式、背贴式止水带技术的基础上开发了蝶形可排水止水带.该止水带属新型中埋式止水带,其断面呈蝶形.安装时将蝴蝶的头部朝向施工缝的迎水侧;从侧面(先浇衬砌段一侧)将止水带压向衬砌段的端头模板,使后浇衬砌段一侧的止水翼变形紧贴端头模板,并用带垫片的钢钉从肋部间隔适当距离逐点固定止水带;先浇衬砌段浇筑并养护一段时间后拆模,先前被压平的后浇衬砌段的止水翼在橡胶等材料弹性的作用下恢复变形;浇筑后浇段衬砌混凝土,即可完成一道施工缝的防水施工.蝶形可排水止水带的优点是:安装方便,容易保证止水带施工质量;属中埋式,可保证在隧道两侧和顶部其周围均能密实;具有可排水功能,在无压力或小压力条件下工作,减少了渗漏机会.