交通荷载作用下承插式综合管廊的动力响应分析

为了解综合管廊在交通荷载下的力学响应特征,文中基于ABAQUS建立了承插式三维综合管廊模型。结果表明交通荷载对作用范围内两节管廊长度的上部结构响应较大,管廊埋深对插口影响较大而对承口影响较小,此外,承插口总体以受压为主,但倒角处拉应力幅值不可忽略。文中结果可为进一步研究交通荷载下管廊响应机理提供参考。     

基于ABAQUS软件盾构法隧道施工中埋地管道力学规律研究

为研究盾构法隧道施工作用下埋地管道的力学性能,建立地层、埋地管道和隧道衬砌的整体模型,采用有限元分析软件ABAQUS进行非线性求解。分别模拟了不同管径、壁厚、埋深条件下的埋地管道应力应变状态,得出在不同影响因素下管道Mises应力和纵向位移的变化规律。分析结果表明:在盾构法隧道施工作用下,管径和壁厚对埋地管道应力应变状态有较大影响,管径越大,管道Mises应力越大,纵向位移越小;壁厚越大,管道的Mises应力越小,纵向位移越小;当管道处在隧道上方时,一定埋深范围内,埋深对埋地管道的应力应变状态影响较小,管道的Mises应力和纵向位移随着埋深的增加虽有增加但增加并不明显。     

大口径钢顶管施工荷载下的受力特性分析

随着我国城市现代化建设的不断发展,地上空间的开发逐渐趋于饱和,地下空间的开发与利用越来越受到人们的重视。顶管法作为一种非开挖技术,在城市隧道管线的建设中具有广泛应用。在施工工况下,顶管管道受力复杂,本文通过对施工工况下的钢顶管进行了有限元建模分析,研究了不同覆土厚度作用下顶管的受力情况,主要分管片内力和管土接触应力两个方面进行了阐述,结果表明:随着埋深的增加,管顶和管底土压力的差异逐渐减小,整个管身的拉压差异也越来越大;接触面上沿截面的分布的纵向摩擦力在管顶和管底处较大,管道两侧较小;环向摩擦力在管顶和管底的位置接近零,管道两侧的应力较大。     

交变载荷作用下埋地天然气管道受力特性

以三维有限元模型模拟埋地天然气管道在内压波动和交通外载等交变载荷作用下的管道应变及应力变化情况,内压波动采用三角波进行模拟,交通载荷以移动形式作用于管道上方,并以矩形面源载荷进行处理。结果表明:当移动载荷作用在管顶上方时,管顶竖向位移变化较为显著,对管侧应变的影响最大,而对管顶和管底应变的影响较小;随着管道内压的波动,管道各点应变也相应变化,在内压最大时管道的总应变达到最大值,管顶和管侧竖向位移则最小,管侧竖向位移变化幅度明显小于管顶。     

管芯外侧带有纵向裂缝PCCP管体承载能力的试验研究

通过对管芯外侧带有纵向裂缝的PCCP(覫2000mm和覫4000mm)进行实体试验,研究其承载能力及其破坏过程。试验结果表明,对于覫2000mm的PCCP,当试验荷载达到1.4倍的设计开裂荷载时,管壁内侧未出现新的可见裂缝;对于覫4000mm管的试验,加压到1.3倍设计开裂荷载时,管底内侧出现新的纵向裂缝;当继续加载时,管体原有裂缝长度增长加宽,与正常完好管试验的开裂位置一致,并在管顶内侧和承插口附近均出现新裂缝,但没有明显降低管体整体的承载能力,不影响正常使用。     

控制性低强度材料(CLSM)在管沟回填中的应用

介绍了控制性低强度材料（CLSM）及其工法的概念和特点，运用有限元模型分析了交通荷载作用下埋地管道在不同回填材料和管顸埋深情况下的横向力学性状。研究发现，CLSM对交通荷栽作用下浅埋柔性管道的减荷效果非常显著，其路面工后沉降也较小，在城市市政管道工程中推广CLSM回填工法具有现实意义。     

静/动载作用下埋地管道力学性能的试验分析

针对埋地管道开展了静载和循环荷载试验,综合分析了荷载类型、加载角度、管道外径和管道材质等因素对管道力学与变形性能以及管周土压力分布规律的影响。结果表明:静载作用下,管周土中垂直土压力大小与加载位置关系密切,水平土压力受“土拱效应”影响显著;管道呈现水平向外鼓胀、垂直径向压缩的椭圆状变形,且承压板荷载越大,管道变形越严重,同时管顶“土拱效应”越显著。循环荷载对埋地管道上方土层的沉降影响明显大于静载;改变承压板角度时效果差异明显,当加载范围关于管道轴线对称时埋地管道所受影响显著。对比不同外径和材质的埋地管道,发现当厚径比相同时,管径越大,壁厚越大,弹性模量也越大,管道的抗变形性能也就越好;公称压力相同时,聚丙烯管道抗变形能力强于外径相等的高密度聚乙烯管道。     

多种荷载条件下埋地聚乙烯压力管道的变形特征试验研究

文章建立了覆土荷载作用下埋地聚乙烯压力管道反应的实验模型。通过向管内注入压缩空气和改变管顶以上填覆土的厚度,研究了埋地聚乙烯管在多种荷载条件下的力学响应,分析了不同影响因素(工作压力、覆土厚度、管周土体强度)对埋地聚乙烯管变形的影响。结果表明:覆土荷载和工作压力共同作用下,埋地聚乙烯管最大应变点位于管顶;管周土体强度是影响其变形的敏感因素;管最大应变值大小随覆土厚度改变没有明显变化,随工作压力增大而增大,工作压力和最大应变值两者间具有明显的线性关系。     

交通荷载作用下HDPE管道附加弯矩变化规律研究

近年来,高频重载交通作用致使埋地HDPE管道压屈,进而导致管道破坏事故频发。弯矩是评价管道压屈的重要指标之一。然而,现阶段鲜有关于交通荷载作用下管道附加弯矩的相关研究报道。以管道工程中广泛采用的HDPE管道为研究对象,基于现场足尺试验和数值计算,研究了交通荷载作用下埋地HDPE管道附加弯矩的影响因素及变化规律。研究结果表明:(1)相同管道直径和埋深条件下,交通荷载引起管道的超载弯矩比n(即附加弯矩与管道初始装配弯矩的比值)与交通荷载的大小呈线性关系,且n为定值;(2)n的大小与管顶埋深成指数函数关系,管径对n值的影响可以忽略不计。基于现场试验和数值计算结果,本文提出了交通荷载作用下HDPE管道最大附加弯矩的经验公式,并对经验公式的有效性进行了验证。     

交通荷载作用下埋地管道纵向受力计算

为研究车辆行驶通过未经处理的埋地管道上方时管道纵向应力分布形式及其影响因素,采用Winkler弹性地基梁模型,提出相应的简化计算方法,并通过现场试验和数值模拟进行验证。对比理论计算、现场实测数据及数值模拟结果发现,三者所得的管道纵向应力分布规律一致,随管道埋深和管径变化的规律一致;由于存在荷载动力放大效应,管道实际纵向应力明显大于理论计算结果。结果表明:运用Winkler弹性地基梁模型和本文的简化方法计算交通荷载作用下埋地管道纵向应力是可行的;理论计算公式中附加应力扩散角和地基系数取值会对计算结果产生一定影响,但影响较小;可引入动力影响系数对计算结果进行修正,并给出影响系数的建议值。     

Investigating peak stresses in fitting and repair patches of buried polyethylene gas pipes

Nowadays, polyethylene composes a large number of natural gas distribution pipelines installed under the ground. The focus of the present contribution is two fold. One of the objectives is to investigate the applicability of polyethylene fittings in joining polyethylene gas pipes which are electrofused onto the pipe ends and buried under the ground, by estimating stress distribution using finite element method. The second objective is to study the effectiveness of polyethylene repair patches which are used to mend the defected pipelines by performing a finite element analysis to calculate peak stress values. Buried polyethylene pipelines in the natural gas industry, can be imposed by sever loadings including the soil-structure interaction, traffic load, soil’s column weight, internal pressure, and thermal loads resulting from daily and/or seasonal temperature changes. Additionally, due to the application of pipe joints, and repair patches local stresses superimposed on the aforementioned loading effects. The pipe is assumed to be made of PE80 resin and its jointing socket, and the repair patch is PE100 material. The computational analysis of stresses and the computer simulations are performed using ANSYS commercial software. According to the results, the peak stress values take place in the middle of the fitting and at its internal surface. The maximum stress values in fitting and pipe are below the allowable stresses which shows the proper use of introduced fitting is applicable even in hot climate areas of Ahvaz, Iran. Although the buried pipe is imposed to the maximum values of stresses, the PE100 socket is more sensitive to a temperature drop. Furthermore, all four studied patch arrangements show significant reinforcing effects on the defected section of the buried PE gas pipe to transfer applied loads. Meanwhile, the defected buried medium density polyethylene gas pipe and its saddle fused patch can resist the imposed mechanical and thermal loads of 22°C temperature increase. Moreover, increasing the saddle fusion patch length to 12 inches reduces the maximum stress values in the pipe, significantly.     

承插口给水排水管道的竖向位移（沉降）计算

本文基于管道竖向变形机理与承插口的相对转动理论 ,探讨了承插口给水排水管道的竖向位移计算模型。工程测试结果验证了本文计算模型的合理性 ,能为给排水管道的合理优化设计、施工及运行管理等提供一定的理论基础。     

Performance and damage evolution of plain and fibre-reinforced segmental concrete pipelines subjected to transverse permanent ground displacement

This paper presents the results of three full-scale experiments performed on segmental concrete pipelines subjected to permanent ground displacement. The first pipeline was made of reinforced concrete pipes and the second pipeline was made of steel fibre-reinforced concrete pipes. The third pipeline was made of a combination of fibre-reinforced and reinforced concrete pipes. An array of sensing techniques was used to assess the damage evolution in pipelines and their overall performance. Three stages of damage were observed. In the first stage, damage was concentrated in the joints near the fault line. In the second stage, the damage occurred in all joints along the pipeline. While in the first two stages damage was mainly concentrated at the bell and spigot joints of the pipe segments, the third stage of damage was characterised by severe damage and rupture of the body of pipe segments located in the immediate vicinity of the fault line. The modes of failure for the plain and fibre-reinforced concrete pipelines were similar in the first and second stages of damage. However, in the pipeline constructed using both plain and fibre-reinforced concrete pipe segments, the damage was concentrated in the standard reinforced concrete pipe segments.     

Evaluation of geocomposite compressible layers as induced trench method applied to shallow buried pipelines

This paper suggests as a rather simple and innovative alternative of the induced trench method with the use of geocomposite replacing EPS geofoam for protection of shallow buried pipes. Laboratory model tests and the numerical studies have been conducted on induced trenches constructed with relatively thin drainage geocomposite, as compressible layers, placed into sand. A parametric study using numerical modelling was conducted considering different arrangements of compressible layers in order to optimize the use of these geosynthetics in rehabilitation and maintenance of shallow buried pipes. It was concluded that geocomposites have compressibility enough to replace EPS using diminished area, which favor the applicability for shallow pipelines protection. Reduction on vertical soil pressures over the crown of the pipe reached values of 90%. The stress reduction at the crown was found to be significant affected by the width of the geocomposite and its distance from the crown of the pipe. The use of a more compressible condition of sand backfill provide more efficiency as far the geocomposite is from the crown of the pipe. Results from numerical modelling also indicate that using more than two geocomposite layers led to negligible stress reductions compared to one layer solution.     

Automated detection of cracks in buried concrete pipe images

The detection of cracks in concrete infrastructure is a problem of great interest. In particular, the detection of cracks in buried pipes is a crucial step in assessing the degree of pipe deterioration for municipal and utility operators. The key challenge is that whereas joints and laterals have a predictable appearance, the randomness and irregularity of cracks make them difficult to model. Our previous work has led to a segmented pipe image (with holes, joints, and laterals eliminated) obtained by a morphological approach. This paper presents the development of a statistical filter for the detection of cracks in the pipes. We propose a two-step approach. The first step is local and is used to extract crack features from the buried pipe images; we present two such detectors as well as a method for fusing them. The second step is global and defines the cracks among the segment candidates by processes of cleaning and linking. The influences of the parameters on crack detection are studied and results are presented for various pipe images.     

静载作用下土工格栅加筋防护埋地管道力学性能的实验研究

 针对土工格栅加筋防护埋地管道开展了静力载荷实验,研究管周填土相对密实度(Dr)、管道埋深(H)、筋材长度(L)和层数(n),以及首层筋材埋深(u)等对埋地管道防护性能的影响。实验结果表明：首层筋材最佳埋深为0.4B(加载板宽),筋材最佳铺设长度为4D(管道外径),筋材层数以3～4层为宜;同等条件下随着Dr持续增加,管道极限承载力增加,加载板沉降相应减少,且二者变化率明显降低,表明管周土相对松散时加筋效果愈加明显;同等条件下管道水平和竖向径向变形均随地表载荷增加而增加,且竖直径向比水平径向变形略大,通过增加筋材层数能显著提高土体刚度,能有效地分散管道上方载荷,为管道提供减载保护;管道外壁监测点环向应变值位于－1.5%～1.0%之间,顶部以压缩变形为主,其两侧45°处为压缩和拉伸变形过渡区,而水平径向以拉伸变形为主;随着Dr增加,管周环向应变减小,且应变的对称性愈加显著,表明因Dr增加引起土体自身刚度增加,能有效地限制管道移动及变形。     

深埋曲线钢顶管受力特性现场监测试验研究

为了研究深埋曲线钢顶管施工过程中的力学特性,依托拱北隧道曲线顶管管幕工程,对曲线顶管管节轴向与环向应变进行了现场监测分析。实测数据结果表明,管节应变随顶进距离增大而略微增加,但基本保持在一定范围内。管节在顶进过程中应力曲线发生波动,停止顶进后逐渐趋于平稳。管节轴向应力主要受顶进力影响,而环向应力主要取决管节外侧环向荷载,曲线顶管管节弯曲内侧存在压应力集中。由于存在泊松效应,大埋深条件下管节顶部和底部轴向应力受环向变形控制。随着与机头距离增加,管节由轴向两侧受压逐渐转变为单侧受压,受压区位于管节弯曲内侧,应力集中更加显著。     

天然气冷喷加湿工艺的研究与应用

我国大部分城市曾用铸铁管道输送人工煤气,城市燃气管网中的铸铁管道一般采用机械接口的方式连接,机械接口的密封材料采用橡胶垫圈。近几年,城市燃气管道由人工煤气转输天然气后,铸铁管道的接口逐渐出现了泄漏问题。本文探讨了人工煤气转换为天然气后,采用天然气冷喷加湿工艺解决铸铁燃气管道接口泄漏的机理、天然气加湿剂的试验及选择、冷喷加湿系统的工艺的研究以及投资运行经济分析。     

填土强度对埋地钢塑复合缠绕管受力影响分析

钢塑复合缠绕管是一种用于市政工程埋地排污排水的新型管道,在诸多性能方面优于传统的混凝土排水管,目前正在我国的城市建设中进行推广应用。这种管道外层为缠绕钢带,内层为高密度聚乙烯塑胶,是一种新型结构,在埋地受力机理方面,目前的研究做得尚不多。本文采用有限元的数值分析方法,针对不同的回填土情况,对这种管道的管土共同作用受力进行了分析,得出了填土强度对钢塑复合缠绕管管土共同作用受力的影响规律,可供相关的工程设计和施工参考。     

循环荷载作用下格栅防护柔性埋地管道的性能分析

交通循环荷载下埋地管道性能与防护是当前研究的重点问题,首先针对格栅加筋柔性管道开展试验研究,分析管道埋深H为3D(D为管道外径)时循环荷载水平和频率、首层格栅埋深、长度、层间距和筋材层数对管道力学与变形性能的影响,试验结果表明:首层格栅最佳埋深u为0.4B(B为加载板宽度),最佳层间距ug为0.5B,最佳铺设长度L为5D;增加格栅层数能显著增强土体,从而有效减少管道变形和加载板沉降;提高荷载水平或降低荷载频率使管道变形、加载板沉降和格栅应变整体显著增加;格栅应变随其与加载板中心的距离增加而减小,格栅中心点应变随循环次数增加呈现先增加后减少的趋势。进而,基于有限元数值模拟分析管道埋深H、加载板宽度B和管径D对管道力学性能的影响,数值结果表明增加管道埋深或减小加载板宽度,管道径向变形减小;同等荷载作用下,减小管径时管道径向变形增大,筋材加筋效果减弱,适当增加管道直径,有利于筋材加筋作用的充分发挥,从而减小管道径向变形。