地铁隧道施工中桩基托换技术研究

桩基托换作为地铁隧道施工中的一个重要施工环节,其施工质量将直接关系到既有建筑物的安全性与稳定性。为了进一步提升地铁隧道施工质量,基于某工程实例,从托换基础开挖、托换桩及承台施工、既有桩基界面处理及植筋、托换受力体系转换等角度对地铁隧道施工中桩基托换技术展开详细研究,对于类似工程具有参考意义。     

暗挖区间隧道近接既有地铁隧道施工变形影响及控制措施研究

针对新建隧道近接既有隧道施工引起的结构及地表沉降变形问题,文章以成都地铁8号线新建暗挖区间隧道近接交叉下穿既有7号线地铁盾构区间隧道施工为背景,提出了既有线注浆加固土体、新建暗挖段施作超前支护、严格控制施工工艺、以监测预警手段反馈施工的综合控制措施,并详细阐述了施工降排水、管棚及小导管注浆施工要点。研究表明,监测数据表现出强烈的施工过程相关性,其中地表沉降量值最大达9～10 mm,而采用综合控制措施区域内的地表最大沉降则小于7 mm,既有地铁隧道结构最大沉降小于6 mm,均符合设计和规范要求。     

地铁下穿既有线和扩大基础桥梁施工方案研究

北京地铁六号线朝阳门—东大桥区间隧道下穿既有地铁二号线朝阳门站和二环主路朝阳门桥施工,工程难度极大,施工安全控制极为重要。为研究新建隧道施工过程对围岩与既有结构的影响,保证施工期间既有结构的安全使用、有效控制地表沉降,针对本工程拟定了不同施工方案并采用有限元计算软件MIDAS-GTS进行三维仿真模拟,分析其对围岩与下穿建筑物的变形控制效果。依据既有结构沉降控制标准,最终提出采用新建隧道与既有车站零距离刚对刚接触、自隧道两侧同时开挖、在既有车站两侧同时施做水平旋喷桩的方案。该方案将为六号线下穿既有车站和扩大基础桥梁的设计与施工提供理论依据。     

全液压衬砌台车与简易衬砌台车性能比较及适用条件

本文以新建西安－南京铁路刘家山隧道出口及北坪隧道进口衬砌为例，对用于拱墙衬砌的全液压衬砌台车及简易衬砌台车的结构，性能，设备配套，施工组织等进行了比较，同时对全液压衬砌台车及简易衬砌台车的适用条件进行了探讨。     

滨海软土地层盾构近接穿越角度对既有隧道影响的模型试验研究

为研究新建盾构隧道以不同交角上穿施工对既有隧道的影响,文章以福州地铁2号线为工程背景,通过室内模型试验模拟穿越角度分别为0°,30°,60°和90°时盾构上穿施工对既有隧道稳定性的影响.研究结果表明:上穿施工过程中,沿新建隧道纵向土层受扰动影响最大,且离开挖面越近的土层扰动影响越显著;既有隧道各测点附加内力变化规律一致...     

地铁施工对邻近桥梁桩基础内力影响分析

文章采用数值方法研究了城市盾构隧道施工对邻近桥梁单桩、两桩、四桩基础的应力与位移的影响,研究结果表明:(1)隧道施工使单桩近隧道侧轴向应力减小,远隧道侧轴向应力增大,其影响程度随桩与隧道水平距离的增大而减小;(2)隧道施工下穿两桩或四桩群桩基础后,桩身近隧道侧轴向应力增大而远隧道侧轴向应力减小;(3)隧道施工对群桩的影响远大于单桩,其中距隧道较远桩顶两侧应力差在隧道施工后显著增大,承台距隧道较近时远隧道桩上部混凝土可能承受拉应力作用;(4)桩竖向位移随桩与隧道距离增大而减小,若桩底位于隧道底面以下,则隧道施工后桩产生较小沉降值;(5)桩受隧道施工影响一般在桩顶水平位移最大处,桩与隧道较远时位移值随桩深线性减小,较近时呈非线性减小趋势,其中桩上部位移沿桩深减小较快,桩下部位移收敛到定值,桩顶位移在桩与隧道一定距离时最大。     

盾构隧道近距离下穿高架桥主动预支护研究

地铁隧道与高架桥同期修建或紧邻相继施工的情况越来越多,其传统被动支护措施存在控制效果有限、支护结构施作扰动剧烈、受环境空间限制可选择性小等弊端。文章以济南轨道交通R1线盾构隧道近距离下穿拟建高架桥为工程依托,提出了框架结构、三轴搅拌桩结构及隔离墙结构3种主动预支护技术,分析了不同预支护工况的地表沉降特征、桥桩变形规律及管片主应力分布情况。研究表明:不同预支护工况下,隧道地表沉降、桥桩变形及管片主应力呈现不同趋势。无预支护时,桥桩变形及管片压应力最大;随着框架结构间距的不断减小,承台外缘变形逐渐增大,承台中心变形逐渐减小;三轴搅拌桩刚度较小,隔离控制效果较差;多框架结构、搅拌桩植桩结构及隔离墙结构的加固控制效果逐渐增强;实际施工中,多框架结构对各项控制指标的加固效果较为均匀,且经济性好、施工便捷,应优先考虑,而搅拌桩植桩结构及隔离墙支护在不良地质区域具有一定优势。     

地铁区间盾构隧道对周边建筑物结构基础影响分析

针对区间新建隧道近接既有桩基的地铁工程,进行了三维有限元数值模拟的施工力学行为研究.研究结果表明与无桩情况相比较,近接桩基施工将引起新建隧道自身结构,特别是与既有桩基近接一侧边墙,不利的受力特征,并且近接施工还将引起既有桩基产生偏向隧道水平方向的"拉伸"变形情况.因此,需要采取加固措施,以确保隧道自身结构以及近接地下建筑物的安全.此外,考察不同刚度折减系数时,发现桩基水平侧向变形几乎没有变化,这表明改变盾构管片的拼装方式,在整体上对近接地下建筑物几乎无影响.     

北京地铁五号线崇文门站施工中允许地表沉降分析

建设中的北京地铁五号线崇文门站下穿既有地铁一号线区间隧道及众多地下管道,为保证既有地下铁道正常运营和地下结构的安全,需严格控制新建车站施工引起的地层位移.文章结合新建车站的暗挖施工及地下管线和既有线铁道的实际情况,计算和分析了穿越既有线地铁段施工的地表允许沉降值,可为制定合理的施工方案提供参考.     

盾构隧道穿越桥梁桩基群的桩基托换技术研究

为探析盾构隧道穿越桥梁桩基群中桩基托换过程的受力转换机理及盾构隧道掘进对群桩基础结构的影响,文章以深圳地铁10号线盾构隧道穿越广深高速桥梁桩基群为工程背景,采用FLAC~(3D)开展桩基托换与地铁隧道施工的数值模拟。研究结果表明:桩基托换后,桥梁荷载体系从桥面板→桩基→地基土转换为桥面板→既有桩基+托换桩→地基土,被托换桩的上覆荷载能够有效地转移到新建托换桩上;在桩基托换与盾构掘进过程中所产生的沉降变形能够提高桩端阻力与桩侧摩阻力,使得桩基结构的最大主应力有所降低;桥梁桩基沉降量以盾构隧道推进过程中由地层损失和掘进扰动产生的沉降变形为主,桩基托换所产生的沉降量占总沉降量的20%~30%;桩基沉降变形、侧向位移与主应力降低效应均主要表现在托换桩上,非托换桩变化不大;盾构隧道管片衬砌结构变形主要产生在桩基托换区域附近,且以沉降变形为主,水平位移较小。     

双连拱隧道施工阶段衬砌裂损状态成因的研究

文章针对双连拱隧道施工期间衬砌裂损出现的过程、状态、分布特点及现场处置,综合现场勘查、施工过程分析、地形地质等因素,定性研究了衬砌致裂成因,建立了隧道进口衬砌裂损区段施工过程数值分析模型;考虑隧道所处位置实际地形条件、围岩构造参数、实际施工工序等,重点研究了衬砌结构内主应力的分布规律.研究结果表明,衬砌裂损的主要成因是偏压荷载作用造成局部应力大于正常设计承载力;由于地质构造复杂,施工中考虑不周、对塌方区处理固结不充分,加之施工中多次扰动、左右线相互影响等,使围岩松动软化.文章从理论上解释了该隧道衬砌裂损产生的机理,其结果与现场实际相吻合.     

提高侵蚀环境下山岭隧道衬砌混凝土耐久性施工对策研究

通过调查发现,我国既有山岭隧道结构耐久性普遍不足,许多隧道运营后不久衬砌结构就出现了开裂、渗漏水、溶蚀结晶、甚至出现拱顶掉块,造成隧道结构耐久性不足,其原因有设计原因也有施工方面的原因.文章针对既有隧道的病害表现,分析了隧道衬砌耐久性不足在施工方面的原因,并提出了解决新建隧道衬砌混凝土耐久性的主要施工对策:采用多元复合胶凝材料及合适的混凝土搅拌工艺;采用低水胶比、低用水量和高性能减水剂;采用先进的灌筑和振捣工艺、合理的养护技术及拆模和养护时间等.     

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.     

基于SVM的隧道衬砌空洞填充物雷达图像识别研究北大核心CSCD

衬砌背后空洞及其填充物对隧道结构安全具有重要影响,开展空洞探测识别对于结构安全评估和病害处置具有重要意义。首先采用室内试验和FDTD正演模拟相结合的方法,获得了空洞内填充空气、水、干砂、湿砂条件下的雷达图谱数据,并对不同填充物波形规律进行对比分析;然后,基于支持向量机算法对波形特征进行提取和分类识别,建立了一种空洞填充物的人工智能辨识方法。研究结果表明,采用傅里叶变换前的平均值、方差、平均绝对离差和傅里叶变换后的最大幅度值max(fft(X))四个统计量作为支持向量机的识别特征,可以有效区分出衬砌背后填充物的六种类型;当采取单一倾向数据时,识别准确率较好,六种物质二分类问题准确率均可以达到90%以上。     

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.     

非规则梁式桥地震响应分析

文章以百色巴明非规则梁式高架桥为研究对象,通过建立有限元模型,探讨了该桥的自振特性,并利用反应谱法和时程分析法,计算分析了不同工况下桥梁的地震响应情况。     

龙潭特长公路隧道运营通风方案比较

龙潭隧道系沪蓉国道主干线宜昌至恩施公路上的特长隧道,长约2×8.7 km,是控制全线工期的重点工程,其运营通风又是整个设计中的关键一环。文章结合工程实际情况,从通风、防灾救援和施工组织等因素综合考虑,介绍了通过技术经济比选确定的相对可靠、经济实用的运营通风方式。     

悬浇连续梁墩梁临时固结技术的验算与应用

广西靖西至那坡高速公路百大特大桥采取临时固结的方式进行预埋粗钢筋锚固施工,文章结合该工程实例,通过建立简支双悬臂结构在四种荷载工况下的计算模型,分析了悬臂浇注连续箱梁施工临时固结的最不利荷载工况,以及在此工况下临时支座的受力情况,并对临时支座及临时锚筋进行了相应的结构计算。     

Development of a representative urban driving cycle construction methodology for electric vehicles: A case study in Xi’an

This paper develops a systematic and practical construction methodology of a representative urban driving cycle for electric vehicles, taking Xi’an as a case study. The methodology tackles four major tasks: test route selection, vehicle operation data collection, data processing, and driving cycle construction. A qualitative and quantitative comprehensive analysis method is proposed based on a sampling survey and an analytic hierarchy process to design test routes. A hybrid method using a chase car and on-board measurement techniques is employed to collect data. For data processing, the principal component analysis algorithm is used to reduce the dimensions of motion characteristic parameters, and the K-means and support vector machine hybrid algorithm is used to classify the driving segments. The proposed driving cycle construction method is based on the Markov and Monte Carlo simulation method. In this study, relative error, performance value, and speed-acceleration probability distribution are used as decision criteria for selecting the most representative driving cycle. Finally, characteristic parameters, driving range, and energy consumption are compared under different driving cycles.     

统计方法在沥青路面施工管理中的应用

文章介绍了统计方法在沥青路面施工质量动态管理中的应用,提出了用平均值-标准差控制图、平均值-极差控制图,对沥青路面施工过程中的检测数据进行动态分析,及时检查出施工中的变异性环节,使沥青路面的施工质量处于较为理想的受控状态。