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.

Analytical model of vertical load acting on jacked pipe considering soil arching effect in cohesionless soil

For the project of pipe jacking in cohesionless soil,it is key to determine the vertical load on jacked pipe so as to predict the jacking force accurately.In this paper,a new parabolic soil arching model was proposed to calculate the vertical load on jacked pipe.This proposed analytical model was composed of parabolic soil arching zone,parabola-typed collapse zone and friction arch zone.Combined with existing literature,the key parameters(i.e.,height of parabolic soil arching,horizontal pressure coefficient and width and height of friction arch)were determined.In addition,considering that the trajectory of major stress is parabola,the formula of horizontal pressure coefficient was deduced in the friction arch.The parabolic soil arching zone is assumed as a three-hinged arch with reasonable arch axis,and the formula of load transfer was derived considering the transition effect of parabolic soil arching.The results of experiment,theoretical models and numerical model were adopted to verify the proposed analytical model.Finally,the influence of the key parameters on the vertical load on jacked pipe were also discussed in detail.This work provides a meaningful reference for evaluating the vertical load on jacked pipe for design of pipe jacking.

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.

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.

Novel wreck salvaging method using curved rectangular pipe basing method:A case study of"Yangtze River EstuaryⅡ"ancient shipwreck salvage project

Shipwreck salvage is a risky,time-consuming,and expensive process.Although there are many sunken ships along coastlines and in the open seas,the salvage process of a sunken ship has rarely been reported.The integrated salvage of the"Yangtze River EstuaryⅡ"shipwreck used a novel method with 22 closely locked curved rectangular pipes to form a watertight base that wrapped the shipwreck inside.The basing was lifted out of the water using a powerful crane situated on an engineering ship.For the first time,the tunneling method was used in a shipwreck salvage project,significantly reducing the disturbance to the shipwreck and its stowage,thereby preserving the original state and integrity of the shipwreck to the greatest extent.In this study,the basic concepts of the salvage method and process are explained.Solutions to critical issues in the new salvage method are provided,including jacking force prediction and major considerations for the structural design of the salvage system.The design of the salvage system and salvage process of the"Yangtze River EstuaryⅡ"shipwreck are introduced.The monitored jacking force,pipe deformation,and observed water-tightness verified that the proposed method was effective and efficient.Other possible application scenarios for the proposed method are presented at the end.

Study on the pipe friction resistance in long-distance rock pipe jacking engineering

Previous studies on pipe friction resistance are mainly concentrated in the soil layer,whereas the study on that in the rock stratum is limited.To estimate the pipe friction resistance in the rock stratum,the calculation models of pipe friction resistance and their applica-tion conditions were compared first.Then the friction resistance calculation model for pipe jacking in the rock stratum was established and simplified.Lastly,the measured(FM)and the computed(FN)pipe friction resistance was compared to validate the simplified friction resistance calculation model.The following conclusions can be drawn:(1)The existing calculation methods of pipe friction resistance can be well verified in the soil layer but cannot be applied in the rock stratum.(2)Sediment,pipe–rock friction coefficient and mud buoyancy are the main factors affecting the pipe friction resistance in long-distance rock pipe jacking engineering.(3)The simplified calculation model established by Deng et al.can estimate the pipe friction resistance in different rock strata at different jacking stages with satisfac-tory outcomes.Further research on the pipe-rock friction coefficient in different rock strata with different pipe–rock contact conditions merits further investigation to better predict the pipe friction resistance in the rock stratum.The research results have certain practica-bility and can provide a reference for similar projects.

Dynamic prediction of moving trajectory in pipe jacking: GRU-based deep learning framework

The moving trajectory of the pipe-jacking machine(PJM),which primarily determines the end quality of jacked tunnels,must be controlled strictly during the entire jacking process.Developing prediction models to support drivers in performing rectifications in advance can effectively avoid considerable trajectory deviations from the designed jacking axis.Hence,a gated recurrent unit(GRU)-based deep learning framework is proposed herein to dynamically predict the moving trajectory of the PJM.In this framework,operational data are first extracted from a data acquisition system;subsequently,they are preprocessed and used to establish GRU-based multivariate multistep-ahead direct prediction models.To verify the performance of the proposed framework,a case study of a large pipe-jacking project in Shanghai and comparisons with other conventional models(i.e.,long short-term memory(LSTM)network and recurrent neural network(RNN))are conducted.In addition,the effects of the activation function and input time-step length on the prediction performance of the proposed framework are investigated and discussed.The results show that the proposed framework can dynamically and precisely predict the PJM moving trajectory during the pipe-jacking process,with a minimum mean absolute error and root mean squared error(RMSE)of 0.1904 and 0.5011 mm,respectively.The RMSE of the GRU-based models is lower than those of the LSTM-and RNN-based models by 21.46%and 46.40%at the maximum,respectively.The proposed framework is expected to provide an effective decision support for moving trajectory control and serve as a foundation for the application of deep learning in the automatic control of pipe jacking.

Developments and research directions in pipe jacking and microtunneling

This paper provides a review of the history and development of pipe jacking and microtunneling methods with extensive referencing to the published literature.The application of such methods in comparison with other trenchless technologies is discussed and the various planning,design and construction aspects are introduced.The emphasis of the paper is to trace the academic research and field monitoring results covering critical aspects of design and construction with a particular emphasis on jacking force estimation and the effect of lubrication on jacking forces.

Analysis of jacking forces during pipe jacking in granular materials using particle methods

Trenchless technology is often used in congested urban areas or river crossings to install underground pipelines to minimize disturbance to surface traffic or other activities.Pipe jacking is a typical technique applied to jack pipe segments between two working shafts.However,the design of the jacking force is usually implemented using empirical methods.It should be emphasized that the jacking force will change for each site,depending on the magnitude of overcut,lubricants,work stoppages,geology and misalignment.A particle method is proposed to estimate the jacking force along the pipe.The microparameters are calibrated for sandy soils in Shenyang,so that the macroscale material behavior can be reproduced using the particle model.Hence,the normal force around the pipe circumference can be derived in the particle model,after which the interface friction coefficient is applied to evaluate the friction resistance mobilized at the soil-pipe interface.A modified Protodyakonov’s arch model can be used to assess the magnitude of earth pressure acting on the shield face.In the end,the combination of friction resistance and face pressure provides the jacking force.The efficacy of the proposed particle method is demonstrated by comparing calculated jacking forces with those measured in the field for three types of jacking machines in sandy soils under the Hun River,Shenyang.

Analysis of the influence of geometrical parameters of circular steel pipe with flange plate on the jacking force

Jacking force is one of the important safety indicators during pipe jacking construction.Existing models for calculating jacking force are widely used in the calculation of jacking force for pipe with regular cross-sections.In this paper,considering pipe-soil interaction,the cross-sectional characteristics and the distribution characteristics between pipe and soil,the calculation equations for the jacking force of circular steel pipe with flange plate were proposed based on the pressure arch theory.The proposed equations were applied to calculate the jacking force for the Olympic Sports Center Subway Station of Line 9 in Shenyang,China,and the results were compared with the field monitoring data to predict the accurate jacking force.Based on the proposed equations,the influences of the flange plate position and steel pipe diameter on earth pressure around the pipe were analyzed.The functional relationship between the earth pressure and the position of flange plate or the pipe diameter was obtained,which provides design basis and theoretical guidance for engineering practice.

Investigation of the first quasi-rectangular metro tunnel constructed by the 0-θ method

Quasi-rectangular shield tunneling is a cutting-edge trenchless method for constructing metro tunnels with double tubes,owing to its advantages in saving underground space and reducing ground disturbance.However,the conventional quasi-rectangular shield tunneling method is not applicable when constructing a tunnel without a center pillar,such as a scissor crossover section of a metro line.Therefore,the O-0 tunneling method,which combines the quasirectangular shield and pipe jacking methods,was investigated in this study to solve the aforementioned construction challenges.This study presents a case study of the Sijiqing Station of the Hangzhou Metro Line 9 in China,in which the O-0 method was first proposed and applied.Key techniques such as switching between two types of tunneling modes and the tunneling process control in complex construction environments were investigated.The results demonstrated that the O-0 method can address the technical challenges presented by the post-transition line with a high curvature and a scissors crossover line.In addition,the adoption of the 0-0 method ensured that the transformation between shield tunneling and pipe jacking was safe and efficient.The ground settlement monitoring results demonstrated that the disturbance to the surrounding environment can be limited to a safe level.This case study contributes to the construction technology for a metro tunnel containing both post-transition lines with a small turning radius and a scissors crossover line.A practical construction experience and theoretical guidance were provided in this study,which are of significance for both the industry and academia.

Evaluation on cutting performance of novel PDC cutter for pipe jacking machine

It is inevitable to cut reinforced concrete(RC)appeared in cross passage of city metro by cutting tools when constructing in densely populated area.The previous cutters employed to cut RC are insufficient and easily damaged,so a new polycrystalline diamond compact(PDC)cutter is used to solve this question.Based on the theoretical analysis of cutting mechanism,both circular and tapered PDC cutters with cutting edge angle of 90
and negative front rack angle of 10
are used to cut RC.The peeling and breaking patterns of cutting concrete are proposed,the nodular and grainy chips are the preferred modes in cutting steel bars.The LS-DYNA is employed to investigate the cutting performance in advance.The simulation results show that the average and peak cutting forces increase with the growth of penetration depth,cutting speed,and roundness,and subsequently the recommended penetration depth less than 1.2 mm is obtained to cut RC due to the existence of steel bars.Moreover,the linear cutting platform is adopted to investigate the force ability and damage state of PDC cutters.It is concluded that the cutting force increases abruptly and fluctuates heavily when cutting the coarse aggregates.The patterns occurred in both numerical and experimental results are generally similar.Notably,the steel bar is pulled out and the PDC cutter is damaged at the penetration depth of 0.8 mm,while a good cut occurs at the penetration depth of 0.3 mm.The tapered PDC cutter with a relatively low cutting force is prone to be broken compared with circular PDC cutter.It is suggested that the circular PDC cutter at the penetration depth of 0.3 mm should be used to cut RC in practical engineering.

BIM for the Underground-An enabler of trenchless construction

The subsurface space in urban areas is an important asset.However,the information available on this environment is relatively poor compared to above ground information.This paper proposes a Building Information Model(BIM)for underground applications as means to address this information gap.The creation and progressive update of BIM for a constructed artefact ensures that data on the structures is available and can be used throughout its lifetime.A BIM for underground applications integrates data on surface structures,such as buildings,and subsurface infrastructures,such as pipes,along with details of the surrounding ground,the associated soil and rock properties and groundwater regime into a single framework.This approach is demonstrated by applying it to trenchless construction operations,including a microtunnelling project for a new sewer.The data from this extended BIM concept can be interactively used with analysis packages to conduct risk assessments for new construction activities.It also shows how BIM for the Underground can be used throughout the planning,construction and post-construction stages of a project,and,importantly,how this information can be available for future projects.