Discussion on the Application of Pipe Jacking Construction Technology in Municipal Road Drainage Projects

In the construction of municipal road drainage projects,pipe jacking construction is a relatively common construction method.This construction technology can avoid a large amount of excavation work,improve drainage construction efficiency,avoid large-scale damage to the road surface,and exert small traffic impact.Therefore,it is currently widely used in drainage construction,but judging from the current actual application situation,there are still many problems that require further improvement.This article mainly analyzes the advantages of and current technical problems in pipe jacking construction technology in detail,explores corresponding solutions,and lays a foundation for the optimization of municipal road drainage engineering construction.

Application of ANSYS 3D FEM in Studies of Surface Deformation Caused by Pipe Jacking

By using site observation data and establishing 3D model using ANSYS software, this paper has discussed the strain change of stratum stress during process of jacking-in and the impact of machine head on ground surface under different frontal resistances. Analysis of the two cases shows that soil pressure reaches its maximum point when the soil is right above machine head, and soil stress will gradually decline when machine head passes over it. It also shows that impact brought by pipe-jacking construction on stress change of the surrounding soil is limited. The thesis suggest that road surface should be consolidated and soil condition be improved before construction to prevent loss and disaster caused by road surface deformation, jacking force can be increased so that jacking efficiency can be enhanced when ground stratum is well filled with soil, but the frontal resistance facing machine head should be equal to surrounding soil pressure in order to avoid rise of ground surface.

Behavior of Surrounding Soil during Construction and Its Countermeasures Using Pipe Jacking Method in Deep Strata

In Japan when urban infrastructures need to be constructed, the difficulty of utilizing the ground or shallow strata will lead to a more frequent use of the deep strata. The common construction methods are open-cut, pipe jacking, and shield methods. In recent years, a new pipe jacking method has been established that can be adapted to 20 m below the ground or more. Using this method, the drivage machine and the jacking pipe continue to move an underground until the completion of the driving. Therefore an over-cutting area (so-called tail-void) must be formed to lower the friction between the ground and the pipe. The tail-void is filled with lubrications. However, because the stress release from the ground continues to advance when the tail-void is formed, hence there are some challenges required to cope with the stability of the surrounding ground. In order to utilize the pipe jacking method in the deeper strata layers, the theory, analysis and installation of tail-void have to be systemized, and such systematic data must be stored. Therefore, the conditions of tail-void in the deep pipe jacking method are discussed using numerical analyses.

Effect of Application of Pipe Roof Method by Using Pipe Jacking on Behavior of Surrounding Soil

Tunnels in an urban area, in many cases, are constructed in soft ground which contains underground water, near existing facilities and structures. Structural stability for the tunnel and also the nearby structures and facilities is vital in this kind of work. Slurry pipe jacking was firmly established as a special method for the non-disruptive construction of underground pipelines of sewage systems. This method utilizes mud slurry that is formed around the pipes in order to stabilize the surrounding soil. In the pipe roof method the tubing elements that are constructed by slurry pipe jacking are near each other longitudinally, and create a rigid and stable lining before the excavation of the main tunnel. This paper discusses ＇the application of a slurry pipe jacking system on ＇the pipe roof method by means of numerical analysis. Because of the rigid behavior of the lining, the results show little subsidence, making this method a reliable method of constructing large tunnels with small cover in an urban area.

Long-Distance Pipe Jacking in Complex Urban Geological Environment

A steel underground pipeline with a diameter of 2.4 m and a total length of 3,617 m(plate thickness of 26 mm)has been constructed in a city in central Hubei,and the engineering,procurement,and construction(EPC)project has been lifted from the upstream channel to supplement water to the downstream lake inside the city.Through preliminary geological survey data,site topographic and geomorphic survey,urban construction,as well as the requirements of the construction party,the preliminary arrangement of working wells and receiving wells as well as the selection and customization of pipe jacking machines have been proposed.Frequency conversion motor and remote monitoring technology are adopted for geotechnical change and long-distance pipe jacking.Through detailed survey,the rock and soil change section as well as gradual change conditions have been determined,the accuracy of construction mechanics calculation and construction operation control have improved,the basis and analysis basis are provided,and some experiences in construction operation are summarized.

World’s first implementation of close-fit pipe jacking of twin tunnels for construction of subway station--Innovation in equipment and construction technology

1 Project overview The Shasan station of Phase II of Shenzhen’s urban rail transit Line 12 is situated in Bao’an District,Shenzhen.It comprises a two-level underground island platform station,measuring 212 m in length,and 22.6 m in width,with an overburden thickness of about 7.0 m.Fig.1 illustrates the presence of a large underground reinforced concrete stormwater culvert,measuring 11.5 m by 3.6 m,traversing the station’s center.

大截面矩形顶管施工对既有管线影响研究

顶管施工会扰动邻近建筑物,危及工程安全。该文以苏州市城北路综合管廊元和塘段顶管工程为背景,通过ABAQUS有限元分析软件建立三维模型,研究顶管下穿地下管线施工对管周土及既有管线影响,并基于极限分析方法探讨了管线失稳模式。结果表明:大直径矩形顶管顶进方向的影响范围约为2倍顶管宽度,两侧的影响范围约为1倍顶管宽度,地下管线到顶管轴线的水平距离为0.5倍~1倍顶管宽度时,应注意管线受到的水平方向附加荷载是否会导致管线破坏;管线与顶管相对位置对管线破坏影响较为显著,越靠近顶管的管线破坏越严重,滑移线由顶管两侧经由管线向地面发展,破坏部位由管线顶部两侧延伸至底部;除受与顶管相对位置影响外,管线破坏模式还受矩形顶管形状影响,管线顶部及靠近顶管顶角区域破坏风险最大。

下穿通道施工全过程对既有地铁隧道变形的影响

为研究下穿通道施工全过程对邻近既有地铁隧道的变形影响,以郑州市金水路(西三环至东四环)项目东明路行人非机动车下穿通道工程为背景,采用有限元软件Midas GTS建立三维数值模型,分析顶管及基坑施工过程对既有地铁隧道的变形影响;总结了新建下穿通道施工全过程对邻近既有地铁隧道的水平位移和沉降变化特征,并将模拟值与工程监测数据进行对比分析,验证数值模型的可靠性。结果表明:下穿通道工程施工全过程中诱发地铁1号线隧道的最大水平位移为0.52 mm,最大竖向位移为2.12 mm,既有地铁隧道的水平位移及竖向位移最大值均满足控制标准。本文研究成果可为类似工程的设计、施工和监测提供一定的参考和借鉴。

矩形顶管临近地铁施工地表变形特性

伴随城市地下空间的利用与开发,对于矩形顶管工程的应用愈加广泛,为探究临近地铁隧道情况下,矩形顶管近距离施工时地表的变形规律,依托顶管工程,利用MIDAS-GTS-NX软件进行顶管施工全过程模拟,分析了各施工参数数值的改变对地表变形的影响。结果表明:(1)顶管顶进过程中,顶管机刀盘前方土体受挤压产生隆起变形,后方因地层损失以及出土卸荷而出现地表沉降,开挖面处地表隆起变形较大,地层扰动明显;(2)在一定范围内,增加掘进压力可以有效维持掌子面稳定,减小地表沉降,降低对周围建筑及临近地铁造成损害的风险;(3)增大注浆压力可以控制土体扰动,减小地表沉降,但本工程条件下,超过140 kPa会出现过度补偿作用,反而增加地表沉降;(4)摩阻力相对于掘进压力与注浆压力对地表变形的影响较小,但地表整体沉降反映出随摩阻力增大而增大的趋势。

反拉式顶管法施工联络通道对地铁盾构隧道力学性能影响

为探究采用反拉式顶管法施工盾构隧道联络通道过程中主隧道的力学响应机制,依托北京地铁某盾构区间,建立模拟联络通道施工过程的有限元模型,通过与现场监测数据对比验证模型的准确性。继而研究联络通道施工对主隧道管片间错台位移、特殊管片应力及变形、螺栓受力的影响,并分析反力模式对主隧道管片力学特性的影响。结果表明:1)始发管片破除对主隧道力学性能影响较大,随着联络通道进一步开挖,主隧道受力和变形缓慢增大。2)管片间最大错台位移为1.17 mm,发生在特殊管片与普通管片接缝底部。特殊管片最大拉应力为18.6 MPa,出现在开口的顶、底部;最大压应力为27.0 MPa,出现在开口的腰部;最大横向扩张位移和竖向收敛位移分别为2.13 mm和4.56 mm。主隧道管片环间螺栓最大拉应力为213 MPa。3)背推式反力模式更利于控制开口处的横、竖向位移,反拉式反力模式更利于控制开口对面管片应力变形及其接缝处错动位移。

软土地层双洞口顶管接收井下沉力学特性研究

相较于常规沉井,顶管接收井几何形式的差异对结构受力、变形的影响规律尚不明确,亟待对此展开深入研究。以武汉市某排水顶管工程矩形接收井为依托,对沉井结构受力及下沉姿态开展现场监测,并利用数值模拟进行了对比验证和拓展研究。结果表明:预设顶管接收洞口引起的结构局部刚度降低,会导致结构在初沉阶段受弯效应增强,从而使接收洞口附近的内层钢筋压应力减小并使钢筋转向受拉状态,并且在下沉后期加剧该处钢筋应力变化幅度;因沉井外壁摩阻力增大而产生的附加应力叠加弯矩作用,使结构内、外层纵向钢筋沿井壁厚度方向的内力分布不均。对软土地层进行土体加固,有利于提高顶管接收井结构稳定性和顶管机头接收精度。

泥水平衡顶管下穿运营铁路施工安全影响分析

结合某电厂至呼和浩特市长输供热管网工程泥水平衡顶管施工项目,采用数值模拟的方法,对顶管穿越段京包客专、京包铁路、呼王联络线路基及呼王联络线桥梁变形进行仿真分析,揭示泥水平衡套管下穿运营铁路施工对路基及桥梁的影响。结果表明:客专线路路用便梁和管棚加固、普速线路路基采用管棚加固、桥梁基础采用注浆防护后,既有运营铁路路基及桥梁的变形值均能满足铁路运营的安全要求,根据三种不同等级的铁路,所提出的三种加固设计方案均切实有效、可行。

JCCP三点法外压荷载试验与模拟研究

为验证顶进施工法用钢筒混凝土顶管(JCCP)的承载能力,对JCCP进行了三点法外压荷载试验,并采用ABAQUS有限元软件对试验过程进行了模拟,研究了裂缝产生、扩展过程,并对其影响因素进行了分析。结果表明:底部支撑梁的圆弧转角及其与管体的接触特性对JCCP裂缝的发展和承载能力有显著的影响,有限元模拟时应考虑这些因素。

双线矩形顶管上穿施工对地铁盾构隧道影响分析

针对新建矩形顶管上穿作用下盾构隧道结构受力和变形特点认识不足的问题,以双线矩形顶管综合管廊上穿地铁盾构隧道工程为背景,通过建立三维有限元模型,研究既有盾构隧道在双线矩形管廊上穿施工诱发下的管片及其接头变形机制.首先,构建接头受力-位移的关系模拟管片间接头的受力变形过程,并以管环承载性能足尺试验验证其有效性.然后,依托工程实例,进一步建立盾构隧道结构-地层三维有限元模型.最后,对比现场监测和数值模拟的结果,全面分析盾构隧道纵向变形、环间错台和接头剪力等规律.研究结果表明:首次穿越的综合管廊诱发的盾构隧道隆起占据主导,而二次穿越的低位箱涵对最大隆起量贡献仅为9%;主要穿越区内管环呈现竖椭圆化收敛变形,拱顶隆起位移最大,分别为拱腰和拱底的1.15倍和1.35倍;盾构隧道沿纵向的隆起曲线呈现“阶梯状”,隆起位移主要以管片环间受剪切产生的错台为主,其中拱顶错台量最大,为拱腰和拱底的1.1倍和2倍;穿越影响区内管片环间接头剪切力呈现非均匀分布,拱顶和拱腰遭受较大剪力,而拱底所受剪力最小;穿越区边缘位置管片环间接头剪切力最大,约为穿越中心区管片环间接头剪切力的2.6~2.8倍.相关研究成果可为新建隧道上穿盾构隧道保护与监测提供支持.

高水压地层顶管出洞止水环漏浆处理技术研究

在长距离顶管施工过程中,始发洞门可能因长期受地下水压过高、钢套环承压变形、止水胶圈长期受拉应力而失效等原因出现洞门漏浆、漏水问题,从而造成顶力陡增现象,随着顶进距离的不断增加,会出现顶不动的严重后果。为了解决高水压地层顶管出洞洞门止水环漏浆这一技术难题,笔者依托内蒙古引绰济辽工程实例分析了洞门止水环漏浆原因,介绍了一种高水压地层条件下顶管始发洞门止水环漏浆处理方法及关键技术,为类似工程提供借鉴。

顶管近接穿越既有箱涵的施工扰动与变形影响分析

为更好地控制顶管施工对周围建(构)筑物的影响,以上海某圆形顶管近接下穿既有箱涵施工为工程背景,建立了考虑顶管-土体-既有地下箱涵相互作用的三维有限元模型,计算分析了不同土体损失、开挖面支撑力等对周围地层和既有箱涵沉降的影响。计算结果表明:既有箱涵沉降随周围土体损失的增大而增加,两者基本呈线性正相关关系;当开挖面支撑力为初始地层压力1.5倍时,顶管施工对既有箱涵结构的扰动最小,一定程度上可以减少顶管施工导致的周围地层及既有箱涵沉降。最后,分析了多种既有箱涵MJS加固方案,提出了优化的加固参数,可为实际工程提供参考支持。

浅埋矩形顶管施工对临近管线与地表的影响研究

矩形顶管施工引起的地表变形特征与圆形顶管或盾构隧道存在显著差异。为了明确浅埋矩形顶管施工过程中的地表沉降特征以及顶管施工对下方既有盾构隧道的影响,根据现场矩形顶管施工监测结果,分析矩形顶管施工过程中地表的变形规律,以及顶管下方既有盾构隧道的变形情况。传统的Peck公式适用于圆形顶管或圆形盾构隧道,因此采用改进的Peck公式来描述矩形顶管引起的地表变形特征;根据现场监测分析顶管施工引起的地表变形、管线变形和下卧隧道沉降规律。研究表明:改进的Peck公式相比于传统的Peck公式可以准确描述矩形顶管施工引起的地表变形规律;顶管施工引起地表和上方管线的沉降规律是一致的,但与下卧隧道的变形规律存在显著差别。

矩形顶管隧道F型承插接头剪切刚度分析

矩形顶管F型承插接头属于柔性接头,地表超载、地基不均匀沉降等极易导致管节间出现剪切错台变形,进而引发隧道工程灾害。基于目前研究中对该种接头剪切力学特性尚不清楚的现状,考虑矩形顶管隧道F型承插接头构造特征,结合室内接头试验和ABAQUS三维精细化数值模拟,针对接头在剪切荷载下的破坏过程、刚度特性及影响因素等问题开展研究。结果表明:矩形顶管接头发生剪切破坏时,受载管节呈中心对称破坏;不同地层中接头的剪力-剪切位移曲线均分为建立接触阶段、钢套环翘曲阶段和焊缝开裂3个阶段,地基刚度越大时,其相对剪切刚度越大;钢套环厚度和宽度增加时,刚度系数值随之提高;随着钢套环宽度、厚度增大,接头抗剪能力随之提高,但提高的幅度有限,不同厚度、宽度钢套环的屈服阶段刚度系数约为弹性阶段的60%~70%。

地铁车站矩形顶管壳-接头理论模型及纵向变形

针对矩形顶管隧道易受影响产生纵向变形、进而引发接头破坏的问题,提出一种矩形顶管隧道壳-接头理论模型,并以此研究隧道在不均匀沉降作用下的纵向变形。首先,通过室内模型试验,探究矩形顶管隧道接头力学特性;其次,建立壳-接头理论模型,给出接头力学元件的刚度矩阵及其计算方法;然后,建立数值模型,并与室内模型试验结果进行对比;最后,依托20环管节的矩形顶管隧道工程实例,研究不均匀沉降作用下的隧道纵向变形。结果表明:接头破坏表现为闭合间隙、钢套环受力和变形破坏3个阶段,接头的抗剪和抗弯均由钢套环承担;壳-接头理论模型的模拟计算结果与模型试验结果较吻合,验证了模型的实用性和准确性;矩形顶管隧道的纵向变形受地基刚度影响显著,砾砂、粉砂和黏土3种地层对应的隧道最大附加沉降分别为3.72,7.66和12.14 mm,随着地基刚度的减小,隧道接头受不均匀沉降的影响将会增大。

管道顶进用装配式圆形工作井承载性能研究

近年来装配式建筑正逐步应用在地下管道工程中,为了研究管道顶进用装配式圆形工作井的承载性能,结合现场监测的顶管顶进力情况,采用三维有限元方法对装配式圆形工作井的井片混凝土以及连接螺栓进行了受力分析。研究结果表明:通过在管壁涂刷润滑剂、采用触变泥浆进行压浆等减阻措施可以明显降低顶进力荷载,甚至可以使其达到设计值的50%以下;装配式圆形工作井在顶进力荷载的作用下,螺栓受拉情况不明显,仅后座墙位置的井片外侧混凝土呈明显受拉,设计中需要关注,必要时需对该部位制定加固方案;粘贴钢板加固方案相对于粘贴CFRP加固方案具有材料利用率更高、加固效果更加明显的优势。研究成果可为推广装配式建筑在管道工程中的应用提供理论依据和参考借鉴。