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.

Application of decision tree to selection of MTBM for adverse geological conditions

So many potential risks can be identifed for application of trenchless technology especially using microtunneling methods.Unexpected changes in ground conditions,such as encountering boulders,tree roots,ground water and man-made structures such as old foundations are the principal geotechnical risks,which affect the selection of an appropriate microtunnel boring machine.On the other hand,the performance of each microtunneling technique will differ while encountering such conditions.Hence,predicting the potential hazards provides a better safety and risk management plan.In this study,a couple of potentially hazardous situation,which are commonly associated with ground conditions,were identifed and investigated.A decision tree aid methodology was proposed based on geotechnical risk assessment for selection of proper microtunneling technique.Based on the approach the most appropriate microtunneling technique has the minimum risk level either before or after hazards mitigation measures.In order to check the effciency of the approach in practice,selection of microtunnel boring machine for Hamadan sewerage pipeline project was evaluated.Accordingly,an earth pressure balance(EPB)MTBM was selected for the project.

Modeling Microtunnelling Construction Operations with WebCYCLONE

Microtunnelling operations do not reach the highest possible productivity due to influences by different soil compositions.Hence, there is a need for a better understanding of the construction process and of those factors influencing productivity. Theefficiency ofMTBM （microtunnel boring machine） will be increased by that knowledge. In the paper, a flexible simulation module isdeveloped. It helps to analyze the processes and to identify the influence of different soil compositions on the productivity ofmicrotunnelling operations. In view of these objectives, a model describing the microtunnelling process for an actual project at thecity of Recklinghausen, Germany is created by using CYCLONE methodology. Subsequently, the WebCYCLONE is applied toexecute the CYCLONE model in order to get the results. It helps to analyze and identify the influence of different soil compositionson the productivity of tunnel construction with microtunnelling in the job-site.

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.

Interpretation of pipe-jacking and lubrication records for drives in silty soil

In recent years,there has been an increased resort to microtunnelling/pipe-jacking as a means of constructing underground conduits(for water,sewage,gas,and other utilities)to avoid on-street disruption in urban areas.In this paper,technical details of two 1200 mm internal diameter microtunnels in silty sand totalling over 550 m in length are discussed.While average skin friction values are extremely low for both drives suggesting effective lubrication practice,differences in normalised bentonite volumes appear to be responsible for differences in skin friction.Full or near full buoyancy of the pipeline has been demonstrated for the majority of the drive.The frictional stress increase after a stoppage is shown to depend on not only the stoppage duration but also on the normalised lubrication volume.Interpretation of data in the manner presented in the paper is an important means of assimilating experience of microtunnelling in different ground conditions.