针刺法化学灌浆技术在地下隧洞衬砌接缝止水缺陷修补中的应用

根据兰州水源地工程隧洞特点开发了针刺法化学灌浆技术,通过专用灌注针头穿刺橡胶止水垫进行化学灌浆.施工时,灌浆材料通过钢针内部的孔注入到橡胶止水垫背面,形成一道弹性防水,达到封堵漏水、修补缺陷的目的,且对管片无损、可有效缩短工期、避免材料浪费与环境污染.灌浆施工后的隧洞管片接缝渗漏全部消失,满足了隧洞通水条件.     

运营期水下盾构隧道渗漏成因及治理技术研究

针对某运营期内水下盾构隧道出现的管片环缝渗漏、螺栓孔渗水、行车道板接缝渗漏的原因进行分析,从堵水机理、堵水效果、施工难度、施工风险及对既有防水体系的影响等方面进行综合比选,最终确定该水下盾构隧道渗漏治理采用接缝注浆的方案并进行了工程应用。     

基于光纤监测的盾构管片接缝受力研究

盾构法在国内外地铁施工中广泛运用,管片接缝是盾构隧道的薄弱环节,关系到盾构隧道的质量和安全。以深圳地铁11号线南山—前海湾区间盾构隧道工程为依托,利用光纤监测技术设计和开展了盾构管片接缝受力现场试验,直观地了解到盾构施工过程中管片接缝处管片及连接螺栓受力变形的实时状态,得到管片接触应力、螺栓轴向应力及变形的一些规律:(1)不同接缝位置连接螺栓和管片的应力应变都是在试验环后第2环安装完成前迅速增长,之后趋于平缓波动或缓慢增长,第2环后盾构施工对连接螺栓及管片的影响在减小;(2)在试验中连接螺栓的受力变形一般大于管片的受力变形,管片和螺栓的受力变形都还有安全储备,处于安全状态;(3)纵缝连接螺栓的应力应变大于环缝连接螺栓的应力应变,不同接缝盾构管片应力应变规律与螺栓的正好相反。     

某过江地铁盾构隧道管片渗漏水原因分析及治理技术

某过江地铁盾构隧道在建设过程中出现了较多渗漏点,分析了该盾构管片渗漏水的原因,并将渗水情况进行了统计和分类,进而提出了渗漏施工治理措施及管片接缝预防措施。     

南水北调中线一期工程某标段箱涵混凝土质量缺陷预防与治理

结合南水北调中线一期工程某标段箱涵混凝土施工中出现的各种质量缺陷,分析了质量缺陷形成的原因,并分别介绍了箱涵混凝土裂缝渗水、对拉螺栓孔漏水、伸缩缝漏水的处理措施.     

关于盾构法隧道施工中管片衬砌关键技术的探讨

隧道盾构全断面开挖技术具有扰动小、掘进速度快、占地面积少等特点,在大多数隧洞施工中已逐步取代掘进法,而作为盾构法关键技术的管片,作为全断面开挖后隧道的永久衬砌,其工艺和技术是影响隧道整体质量的关键。本文将在比较众多对盾构隧道管片选型和接缝的基础上,对盾构法施工中关键技术的管片施工,即隧道防水、整体线性的控制等问题进行探讨。     

盾构管片整环足尺寸模型试验研究综述

在地铁施工和运营期间,盾构管片在不良工况影响下经常出现变形过大和承载力降低等问题。以优化盾构管片受力和提高安全性能为目的,国内外学者通过整环足尺寸模型试验对管片变形性状和破坏关键性能点进行了大量研究。依据试验对象的不同,分别从未加固类管片和加固类管片对研究现状进行了总结和阐述,明确盾构管片结构整体变形、管片内力、接缝变形、管片裂缝、混凝土应变、接缝螺栓、管片错台量等发展情况,总结管片受力变形规律、极限承载力及破坏特征。明确国内外研究的不足,进一步优化加载装置、加载方式和加固技术,对未来该领域的研究提出进一步展望。     

管片螺栓孔制作技术研究

管片螺栓孔作为预制管片的重要部分,盾构隧道施工中将一种直线形或者有一定弧形的紧固连接件（管片螺栓）通过螺栓孔将各管片组合在一起,形成管道。管片螺栓孔的制作成型质量影响着整体施工拼接进度及地下水渗漏安全。为提高管片螺栓孔一次成型率,满足管片施工质量的要求。根据管片芯棒实际外形尺寸,对弯管、封浆垫片重新开模,量体裁衣,针对不同的模具轴向斜边,标准块、邻接块、封顶块的螺栓孔的预留采用不同的弯管,配合特制封浆垫片,可以确保管片螺栓孔制作成型质量。最终实现了预制混凝土管片模具与芯棒交接处不漏水泥浆,管片环缝及纵缝均≤1mm,水平拼装成环内径误差±2mm,成环外径误差范围（-2mm、+3mm）及形成实操方案。     

谈新疆达坂隧洞工程管片裂缝处理技术

通过工程案例,对TBM法施工隧洞管片裂缝的原则作了介绍,探讨了裂缝处理方法、化学灌浆材料选择、施工技术及检查等技术,指出采用化学灌浆是管片裂缝处理行之有效的一种解决方法,处理后提高了隧洞整体结构的稳定性、整体性、耐久性和抗渗性。     

特急曲线盾构隧道漏水原因及预防

近年来,随着轨道交通在国内城市不断发展,盾构施工技术也在不断发展,特急曲线盾构施工越来越受到各方关注,特急曲线施工隧道质量主要是对管片错台和漏水的质量控制。本文主要针对广州地铁五号线区杨盾构区间小半径隧道成型管片漏水的原因及相应处理措施进行阐述。     

某盾构隧道防水堵漏工程施工技术

分析了广州至佛山地铁隧道某标段渗漏的原因,介绍了治理该隧道工程的堵漏方案及防水材料,着重阐述了管片拼装缝、管片吊装螺栓孔、管片联接螺栓孔、峒门和联络通道与隧道管片联接处、破损管片等部位的渗漏治理工艺。     

上海越江隧道渗漏现状调查与分析

上海黄浦江越江隧道具有直径大、接缝长、埋藏深、水压高等特点,隧道周围软土又极易引起隧道结构变形,从而造成隧道结构防水的复杂性。上海越江隧道防水理论和防水技术在实践中不断提高,盾构法隧道管片自防水能力和接缝防水技术均取得了卓有成效的进步。通过对当前隧道渗漏情况的调查表明,新建的盾构隧道渗漏量较好地控制在0.1L/m²/d以下,矩形段渗漏量相对较大。调查还表明越江隧道的渗漏主要集中于圆形隧道段管片的环缝、纵缝、注浆孔、螺栓孔及管片裂缝、圆形隧道与竖井的井圈部位、竖井与矩形段连接部位、矩形暗挖段的变形缝(施工缝)、结构裂缝等。分析还表明越江隧道渗漏量与沉降累积值并无直接的联系,隧道沉降量大的地方渗漏反而不是最严重的。     

热力盾构隧道先盾后井施工衬砌接头变形机理与控制

先盾后井是热力盾构隧道建设中一种高效经济的施工工法。结合中国首例大断面热力盾构隧道工程,基于纵向等效连续化模型和弹性地基梁理论,对施工过程中衬砌接头受力特征和变形机理进行了分析,并提出控制措施;然后建立了衬砌接头全断面接触面单元数值模型,对控制效果进行分析和评价;最后通过现场监测,得到了不同施工阶段管片纵向轴力及接缝变形规律。研究结果表明:先盾后井工法施工中,衬砌接头变形分为两个阶段:基坑开挖及管片拆除,其中管片拆除为接头变形的主因,基坑施工中,基底卸荷产生的负弯矩作用于隧道上,导致邻近竖井管片底部轴力减小、环缝张开,拆除基坑内管片时,作用于端头管片的残余盾构推力和螺栓预紧力消失,导致管片纵向轴力进一步衰减,环缝二次张开;根据现场监测结果,提出的对邻近竖井的管片纵向拉紧并复紧连接螺栓,进行混凝土铺底及衬砌背后二次注浆的控制措施能够有效控制轴力损失,减小接头变形,施工中环向接缝最大张开量3.51 mm,满足隧道防水要求;采用全断面接触面单元建立的数值模型可以较为精确地模拟施工中管片接头力学行为,其结果可作为控制效果评价参考依据。     

北京地铁运营隧道病害状态分析

基于北京地铁隧道病害检测结果,分析结构形式、配筋和运营时间对隧道病害状态的影响。研究结果表明,管片接缝变形是盾构隧道病害的根源,并由此引发了盾构断面的椭圆化变形、管片的压溃与错台以及盾构隧道的渗漏水。衬砌开裂是矿山法隧道的主要病害,裂缝宽度与深度受运营时间影响大且具有离散性强、随机性大的特点,配筋对隧道结构安全有积极影响。渗漏水受降水的影响较大,多出现于隧道衬砌结构的缝隙,如盾构隧道的接缝、螺栓孔或矿山法隧道的变形缝、施工缝和衬砌裂缝等。衬砌空洞多位于拱顶,形状接近于长条形、正方形和椭圆形,且多伴随着邻近衬砌的开裂。混凝土碳化深度与运营时间成正比,碳化深度和速率在隧道道床位置最大、边墙次之、拱顶最小。裂缝是整体式道床的常见病害,道床在剥离的同时还伴随沿其纵向的扭转。     

基于深度学习的盾构隧道渗漏水病害图像识别

随着城市地铁隧道急剧增加的养护需求,地铁盾构隧道结构病害尤其是渗漏水病害亟需快速精准的识别诊断。利用计算机视觉对盾构隧道进行健康检测是近年来国内外的一种新趋势,但目前渗漏水病害图像的识别效果尚不能满足实际工程的需要。在分析盾构隧道衬砌表面图像特点的基础上,将渗漏水图像分为6种类别,采用深度学习的方法,提出一种新颖的基于全卷积网络的盾构隧道渗漏水病害图像识别算法,并从图像识别结果、错检率和运行时间三个方面与大律法、区域生长法、分水岭法等传统图像识别方法进行对比分析。研究表明:基于全卷积网络的盾构隧道渗漏水病害的图像识别能够有效地避免管片拼缝、螺栓孔、管线、支架等干扰物的影响,特别是在克服管线遮挡方面具有优越的鲁棒性;与传统图像识别算法相比,提出方法在错检率和运行时间上具有较大优势,能够更好地满足工程需要。     

Study on inner force and dislocation of segments caused by shield machine attitude

Attitude deflection of shield machine is inevitable in process of driving forward, therefore, the tail brush, circular shape retainer and even shell of shield machine will extrude the exterior surfaces of segments. The squeezing action acting on segments causes dislocation, stress concentration and even crack in segments. Finite element code, ADINA, was used to analyze numerical tunnel model of 9 segment rings. The loads acting on different segment rings included squeezing action of tail brush under four attitude deflection, jacking forces, grouting pressure and earth pressure. The aspects of analysis included displacement feature and stress distribution. The analysis results indicate attitude deflection of shield machine causes biggish dislocation between segments, and the key segment is the most affected and weakest part in same ring which causes irregular displacement and dislocation in whole tunnel structure. In general, under squeezing action induced by shield machine, circumferential seam is much more affected than longitudinal seam. The squeezing action causes the segment dislocation exceed the limiting dislocation value which means curved bolt has extruded bolt hole and crack or breakage frequently concentrates in key segment and adjacent segment. Deflection of shield machine attitude is inevitable, but two deflection attitudes, including shield machine attitude deviates right direction and the head of shield machine goes down, should be avoided.     

Long-term settlement behavior of ground around shield tunnel due to leakage of water in soft deposit of Shanghai

The lining of shield tunnel is usually composed of segments, in which the joints, cracks, and the grouting holes (hereafter called lining deficit) exist. During the long-term running, soils and groundwater may leak from these kinds of lining deficit. The leaking of soil and groundwater causes the long-term ground loss around tunnel and thus results in the settlement of ground surface. This paper aims to analyze the impact of the leakage of groundwater through segments on the long-term settlement of ground surface. The adopted analytical method is based on the theory of groundwater seepage by using numerical simulation. The analyzed results show that settlement of ground surface increases gradually with the increase of the leaked volume of tunnel segments. When the leaked volume was unevenly distributed, differential settlement occurred locally. Comparative analysis by changing the leaked volume was conducted. The results reveal that there is a linear relationship between settlement and leaked volume when the leaked volume was controlled within the allowable limit.     

Effects of lateral unloading on the mechanical and deformation performance of shield tunnel segment joints

Unloading during lateral excavation widely occurs in existing subway shield tunnels. Previous studies have focused on the overall stress and deformation of existing tunnels caused by nearby unloading. However, the stress and deformation state of tunnel segment joints have yet to be considered. This study considered the non-continuity of the shield tunnel lining and the interactions among tunnel segment, surrounding rocks and ballast bed. A hybrid model of a shield tunnel was established based on 3D nonlinear contact theory. The mechanical and deformation properties of the segments and joints of an existing shield tunnel under the influence of lateral excavation of the foundation pits were studied. Unloading during lateral excavation caused the cross section of the shield tunnel to generate vertical convergence and shift horizontally towards the foundation pit. An opening and dislocation in the joint, which caused the waterproof ability of the joint to decrease sharply, were observed. Meanwhile, stress at the segment joint increased sharply and caused local cracks in the segment lining. Axial and shearing force on the joint bolt also increased significantly. Based on existing subway regulations, the calculation results were combined to establish a deformation control standard for existing shield tunnels under lateral excavation. The rate of vertical convergence of the lining should be less than 3.68‰, and the rate of horizontal shift of the axis should be less than 0.53‰.     

盾构施工中不利工况下隧道结构的力学行为

钱江隧道是目前世界上最大直径的软土盾构隧道工程之一。采用有限元分析方法,对盾构掘进与管片拼装阶段中常见的K块挤入、壁后注浆缺陷、环面不平整、盾构纠偏或曲线推进等不利工况,分析隧道结构的受力和变形特征。结果表明:K块挤入对邻接块的受力状态的影响最为明显,K块宜位于衬砌环腰线以上区域。环面不平整、壁后注浆缺陷和盾构纠偏(或曲线推进)将显著影响盾构推进阶段的衬砌的受力和变形。当环面不平整超过1 mm时,壁后注浆缺陷超过1 m²,或盾构纠偏顶部推力最大时,极易造成管片结构局部开裂、破损。在今后的设计和施工控制中应予以充分考虑。     

Numerical study on crack problems in segments of shield tunnel using finite element method

Crack problems of segments of shield tunnel are analyzed under the conditions of construction stage and service stage. 3D finite element method was adapted to establish elaborate numerical models of segments. For crack problems in construction stage, two models were used to analyze the following contents: (1) crack states of segments under jacking forces; (2) crack states of segments when two segments relatively twist. For crack problems in service stage, first, different external forces acting on segments are abstracted to seven computational models, then crack distribution of these models were analyzed. The analysis results indicate, in construction stage and service stage, cracks mainly appear in circumferential seam, bolt holes and hand holes of segments. Under normal load level, no cracks appear in inner arc and outer arc of segment surfaces. Improving the anti-crack performance of concrete near hand holes and bolt holes, the probability of crack and breakage can be effectively reduced, which can save maintenance expense in service period.