Field performance of concrete pipes during jacking in cemented sandy silt

Although many field investigations into pipe-jacking installation have been reported within the literature, there are few reports on the rebar stress in jacking pipes. This paper presents the field performance of concrete pipes during the jacking carried out under the Guan River in Jiangsu, China. Rebar stresses at two wings (the left and right side), the top crest, and the base in the longitudinal and circumferential directions for four different pipes were monitored. The maximum rebar stresses during the jacking were 37.1 MPa in the longitudinal direction and 36.6 MPa in the circumferential direction. However, the maximum rebar stresses after construction were only 18.5 MPa in the longitudinal direction and 20.3 MPa in the circumferential direction. A normalized jacking force “α” is proposed to evaluate the additional rebar stress in jacking pipes. The range of α is from 0.04 to 0.25. The relationship between the rebar stress and the construction procedure is presented and discussed. An excessive jacking force, an alignment deviation or an increased penetration rate would generate a large incremental rebar stress.     

Key techniques for the largest curved pipe jacking roof to date: A case study of Gongbei tunnel

The Gongbei tunnel, as a part of the Zhuhai Connection highway and Hongkong-Zhuhai-Macao Bridge project, is currently being constructed in Zhuhai, China. To guarantee the tunnel traversing under the Gongbei Port, a combination technology of curved pipe jacking roof for ground support and ground freezing for waterproof is applied. This jacked pipe roof, comprised 36 steel pipe strings of 1620 mm diameter with 355–358 mm gap between adjacent strings, has been faced with various challenges for design and construction due to the site conditions of multiple soft soil and high underground water pressure. These challenges include risks of excessive soil deformation, possibility of path deviation, excessive jacking force, leaking of pipe joint and failure of jacking machine gasketed launch and reception devices. This paper provides an overview of this project, summarizes the most challenging aspects they faced and introduces the relevant techniques applied during construction.     

Construction of a large-section long pedestrian underpass using pipe jacking in muddy silty clay: A case study

This paper presents a case study of constructing a large-section long pedestrian underpass using pipe jacking method in Nanjing, China. The underpass, having a width of 7 m and a height of 4.3 m, was jacked 94.5 m in muddy silty clay under a busy roadway with 6.2 m overburden soil, meanwhile it traverses above the existed shield metro tunnels with just 4.5 m from the underpass bottom to tunnel vault. This paper introduced the design and construction schemes of this project in detail. A pre-construction three dimensional numerical simulation was conducted to investigate the responses of the roadway and metro tunnels to pipe jacking construction. Based on the simulation results, the field monitoring program was proposed, and the tunnels deformation and ground settlement were constantly monitored. The field performances of the metro tunnels and roadway were analyzed according to the monitoring data. In the jacking process, the micro-underbreak method was adopted. In order to decrease the tunnels uplift and ground settlement, the actual volume of soil conveyed out from soil chamber to ground surface was kept 95–98% of theoretical soil volume cut by cutter head. In general, this project is completed successfully without taking any additional time and money-consuming deformation control measures. The ground traffic and underneath metro runs well during the whole construction process.     

A study of jacking force for a curved pipejacking

For a pipejacking, the jacking force is critical to balance the resistance force and to move the pipe string forwards. The driving mechanism of a curved pipejacking is more complicated than a straight-line pipejacking, and its jacking force is also more difficult to be determined. The paper theoretically studies the jacking force of a curved pipejacking by considering the static equilibrium of earth pressure, resistance at cutting face, friction at pipe surface, and the driving force behind the pipe string. The derived theoretical formula can be used to estimate the driving forces of a straight-line or a curved pipejacking. Case study was performed by applying the theoretical and empirical formulae. After calibration, the corrected formula is more accurate and more applicable.     

拱北隧道大直径曲线管幕顶管顶力研究

 以我国在建港珠澳大桥拱北隧道管幕工程为例,研究长距离大直径曲线管幕的施工顶力。总结曲线顶管顶力的主要组成及影响因素;比较和分析中国和日本顶管规范的预测顶力和现场实测顶力的差异;推荐总顶力中迎面阻力的计算公式以及管壁单位摩阻力和摩擦因数的取值;基于力学平衡,推导分节曲线顶管顶力的计算公式。研究表明：泥浆润滑后钢管的管壁单位摩阻力和摩擦因数远小于以往研究中提供的混凝土管的管壁单位摩阻力和摩擦因数;推导的分节曲线顶管顶力公式的计算顶力和实测顶力吻合良好。研究结果可为类似的管幕工程以及供水、污水、供电、通信等管道的顶管设计和施工提供有益参考。     

非开挖管道修复新技术——HOBAS内衬管

本文介绍了HOBAS内衬管修复技术的特点、施工工艺及有关管材、接头、流量、推力等的设计方法，并结合工程案例的成功应用，表明HOBAS内衬管修复技术具有新颖、施工方便、使用寿命长、综合造价低等特点，具有广阔的应用前景。     

浅谈减阻泥浆对大直径混凝土顶管顶推力的影响

本文介绍了减阻泥浆在大直径混凝土顶管中的应用,现场施工得出的数据表明,采用减阻泥浆将大大减小顶管施工中的顶推力。     

Non-destructive evaluation of the grouted ratio of a pipe roof support system in tunneling

The pipe roof system is widely used in the New Austrian Tunneling Method (NATM) as the main support system. Thus, the integrity of the pipe roof system influences the tunnel stability. The purpose of this study is to evaluate the grouted ratio of a pipe roof system using a non-destructive method in the laboratory and in the field. In the laboratory tests, four specimens embedded in soils and five non-embedded specimens are prepared with different grouted ratios of 0%, 25%, 50%, 75%, and 100%. The steel pipes are 6 m in length, 60.5 mm in external diameter, and 3.8 mm in thickness. Field tests are conducted with two fully grouted pipes with dimensions of 12 m in length, 60.5 mm in external diameter, and 3.8 mm in thickness. The reflection method of guided waves, which are generated by a hammer impact and are measured using an acoustic emission sensor, is used for the non-destructive testing. Experimental studies demonstrate that the group velocities and the main frequencies of the guided waves decrease as the grouted ratio increases for embedded and non-embedded specimen in soils. The variation of the main frequency, however, is more significant than the variation of the group velocity. In addition, the group velocities and main frequencies of the field specimens are lower than those of the embedded specimens. This study demonstrates that the variations of the group velocity and main frequency may be used effectively to estimate the grout ratio of a pipe roof system in tunneling.     

Continuation ratio model for the performance behavior of wastewater collection networks

Canada’s aged wastewater infrastructure is failing. New financial and environmental regulatory requirements demand municipalities to estimate operating and capital expenditures for running the systems into the future, and to develop plans for financial sustainability while protecting public health and the environment. Presently, wastewater pipelines’ deterioration is not well understood and realistic deterioration models need to be developed.This paper presents a new ordinal regression model for the deterioration of wastewater pipelines based on continuation ratio logits. The model is presented using the generalized linear model formulation, and takes into account the ordinal nature of the dependent variable and the interaction effects between explanatory variables. The model provides estimates of conditional probabilities for a pipeline to advance beyond a particular internal condition grade – to worse condition – depending on pipe material and age. The model development and validation procedure is demonstrated using high quality condition assessment data for reinforced concrete (RC) and vitrified clay (VC) pipes from the City of Niagara Falls wastewater collection system.The new model is found to represent the RC and VC pipes’ degradation behavior for in-service pipes up to 110 years of age at the City of Niagara Falls wastewater collection system. RC pipes’ deterioration is found to be age dependent while VC pipes’ deterioration is not age dependent. The VC pipe finding is contrary to other deterioration model studies that indicate that the type of pipe material is not significant and that the deterioration of VC pipes is age dependent. The analysis shows, for example, that the predicted conditional probability for RC pipes to advance beyond internal condition grade 3 is estimated to be 60% at 40 years of age and it increases to 90% at 80 years. Similarly, there is a 60% chance of advancing beyond grade 4 to collapsed/collapse imminent condition at 80 years of age for RC pipes. VC pipes are found to have an indefinite service life if installed without structural damage. However, VC pipes exhibited relatively higher conditional probabilities than RC pipes for advancing to worse internal condition grades for pipes up to 65 years of age. Poor installation practices that resulted in pipe defects, such as open/displaced joints and defective connections are deemed to be the factors that resulted in VC pipe deterioration.The findings from the continuation ratio model can be used for risk-based policy development for maintenance management of wastewater collection systems. The proposed model can help in devising appropriate intervention plans and optimum network maintenance management strategies based on pipelines’ age, material type, and internal condition grades. These predictions are critical if realistic wastewater networks’ future maintenance and operation budgets are to be developed over the life of asset and to meet new regulatory reporting requirements. Further research is required to validate the proposed model in other networks and to determine if the method can be used to model the deterioration of pipe materials other than RC and VC.     

浅谈大口径超长距离钢顶管施工顶力控制

分析了青草沙严桥工程C6标DN3 600钢顶管施工中的顶力曲线,结合工程实践,总结了大口径超长距离钢顶管对顶力产生影响的主要因素,并提出了超长距离钢顶管顶力控制的关键要点,以期为类似条件下顶管施工积累经验。     

大口径泥水平衡顶管进出洞技术措施

大口径泥水平衡顶管进出洞技术是顶管工程的关键工序之一,本文根据广州市西江引水工程—输水管线-干线(里和路至和顺立段)DN3600顶管段工程的施工实践,该顶管横穿环城高速路,埋深10米左右,采用封闭式泥水平衡顶管,通过制定的控制措施和预防措施,以及在施工中出现或者可能出现的问题,解决问题的方法及预防措施,通过三个来月的顶管施工发现,顶管机出洞、进洞的工序是关键工序,直接决定了顶管的成功或失败,本文阐述大口径泥水平衡顶管进出洞技术。     

Pipe jacking a sewer under Athens

A deep level sewer installation, employing a trenchless technology method required as a result of excavations for a new freeway in Athens, is described. For the first time, pipes had to be jacked to drive sections over 200 m in length under the city. In addition to its technical merits, the method provided advantages in terms of social and environmental issues. Very little traffic disturbance was caused, together with no disruption of other services or creation of dust pollution during construction. It also did not damage the pavements of the city. This contrasts to the scars left on the roads, due to trenching. Pipe jacking, however, needs the construction of shafts along the alignment, arranged at distances determined by the cost effectiveness of the system to jack the pipes. It was decided to monitor the jacking force requirements as the pipes advanced. This response during driving was then analyzed and compared to the predictions presented by other researchers. Such measurements and analyses may allow for the formation of a database to permit the right choice of an appropriate excavation unit and the successful planning of any future similar projects.     

离心浇铸玻璃钢夹砂管在顶管工程中的应用

本文结合温州市江滨东路污水干管顶管工程介绍了离心浇铸玻璃钢夹砂管在顶管施工过程中有关顶力、偏角、管刚度、径向变形等参数的计算方法,本文工程的实施为今后玻璃钢夹砂管的设计、施工提供了宝贵经验。     

分节预制式多曲线顶管的顶力估算公式

现有的曲线顶管顶力估算公式是由直线顶进公式乘以一个曲线顶管顶力附加系数而来,估算结果与实际工程顶力的匹配程度较低,尤其是在三维曲线顶管工程中,受曲线段的影响,准确估算顶力的难度更大。文章在分析曲线顶管管节静力平衡原理及其传递规律的基础上,提出了一个能够考虑多曲线顶进姿态影响的顶力估算公式,并基于某2.88 m外径、625.0 m顶程的三维曲线顶管实测顶力,对比分析本文公式和规程算法之间的差异,对比结果显示:本文公式的估算结果更能够体现出不同曲线段对总顶力的影响,且在单曲线顶进时与实测顶力的匹配程度更好,能够更好地用于指导工程实践。最后,结合工程实测分析结果,提出了软土地层中不同工况下平均摩阻力的取值建议,为类似工程建设提供依据。     

谈污水顶管的施工与控制

结合工程实际,阐述了污水顶管封闭泥水平衡式顶管的施工原理、特点、流程、施工方法及注意事项,并对顶管施工中的质量控制措施进行了归纳总结,为今后污水顶管的施工提供了参考借鉴。     

均质土中钢顶管顶进稳定性的能量法分析

顶管作为一种非开挖技术,越来越多地应用于各种地下管线工程。钢顶管在顶进过程中,如果顶力控制不当,可能发生轴向整体屈曲,从而导致管体结构失稳破坏。针对这一问题,考虑管周土体的约束、管–土摩阻力以及轴线偏差引起的初弯曲等作用,建立并求解了均质土中钢顶管在轴向顶力作用下的能量方程,获得了临界顶力荷载的解析解。然后,从轴线偏差、管周土体地基反力系数、管–土摩阻力方面分析了钢顶管轴向整体稳定系数的变化规律。钢顶管轴向整体稳定系数随长细比增大而减小,轴线偏差显著降低了钢顶管的轴向整体稳定性。顶管周围土体的约束作用增大了钢顶管轴向整体稳定性。管土摩阻力对钢顶管的轴向整体稳定性影响很小,可以忽略不计。均质土中的钢顶管轴向稳定性规律不同于一般的钢结构,临界顶力荷载解析解可以为钢顶管设计提供依据。     

A method to design microtunnelling installations in randomly cemented Torino alluvial soil

The paper is devoted to improve the applicability of the microtunnelling technique to the metropolitan area of Torino, by producing useful tools to estimate the magnitude of the jacking forces required by the microtunneller and the pipeline to advance into the ground. The subsoil in the city is characterised by a sand and gravel deposit, ranging from medium to highly dense, down to a depth of 8–10 m; below this depth randomly distributed cemented soil (in cases a conglomerate), due to calcareous deposition processes, is often present. A site scale distinct element numerical model able to simulate the excavation of a microtunnel in the partially cemented soil (from non-cemented to fully cemented) was built to investigate the influence of the cementation degree on soil–pipe interaction and to point out the unstable area eventually generated after the excavation of the microtunnel. This led to the definition of an empirical relationship between jacking forces and the degree of cementation in the ground that can be usefully used at the design analysis stage to predict jacking forces. A case study which exemplifies the suggested procedure is also described.     

大口径泥水平衡顶管技术在高地下水位地区的应用

介绍在沿海地区高地下水位地质情况下采用泥水平衡式顶管施工大口径污水管的一些技术。分析泥水平衡顶管施工的关键技术,详细叙述应对高地下水位采取的特别技术和措施。     

垂直顶管计算方法的探讨

本文详细探讨了垂直顶管顶力的组成及其影响因素，并结合工程实践给出垂直顶管顸力的两种计算方法，以便更好地进行垂直顶管的设计和施工。     

顶管技术在湖州市1号污水泵站施工中的应用

以湖州市1号污水泵站施工为背景,介绍了顶管技术在其中的应用,简单概述了工具管的选型、工作井布置以及顶力计算等,详细分析了顶管施工技术措施以及关键控制点,以达到完善顶管施工技术的目的。