Acronyms, Abbreviations, and Initialisms
A list of relevant acronyms, abbreviations, and initialisms....
Summary of Practice
A brief summary of microtunneling practice....
Initial Criteria
Microtunneling is appropriate for a wide range of conditions. Careful evaluation of certain parameters will determine the applicability and constructability of a potential microtunneling...
Site Conditions
The owner and the engineer should visit the proposed site during the initial planning phase and periodically throughout design to identify site conditions and constraints. A survey of...
Preliminary Geotechnical Considerations
In the planning phase of the project, a preliminary geotechnical investigation should be performed to identify the general subsurface conditions and any special subsurface conditions....
Project Layout
Microtunneling projects should be laid out with attention to the benefits and constraints unique to this construction process. The following recommendations address some of these concerns:...
Cost Considerations
Cost is an important consideration when comparing microtunneling with other construction methods. Direct costs should not be the only consideration. Microtunneling has other benefits that...
Detailed Site Investigations
This section addresses site investigation issues that are important for detailed design and construction of microtunneling projects. These site investigations include the following: Geotechnical...
Microtunneling Equipment
A discussion of microtunneling equipment in the context of the design aspects of a microtunneling project is applicable only to the extent that the engineer must set forth in the contract...
Microtunneling Design Elements
The design elements and the process for a microtunneling project are generally the same as for other underground projects. Design elements include the following: General conditions; Special...
Shaft Considerations
Jacking and receiving shaft locations should be selected to minimize the number of shafts and disruptions while not exceeding the practical limits of the drive lengths achievable for a...
Contract Documents
As with any civil works project, the bid and contract documents prepared by the owner and the engineer should provide the contractor with the necessary information to prepare bids, to...
Pipe Characteristics
Microtunneling pipe should meet the following general requirements: Circular shape with a flush outside surface (including at the joints); Strength sufficient to withstand both the installation...
Pipe Design
The pipes and joints, once installed, must be capable of safely withstanding, for the project design life, all in-use service loads, including those associated with the following factors:...
Field Aspects
As soon as practical after their arrival at the project site, all pipes, fittings, and appurtenances should be thoroughly checked for compliance with the contract documents and accepted...
Microtunneling Operation
The shaft should provide safe working conditions and fully support the ground. Jacking and receiving shaft support system and sizes are typically determined by the contractor. See Chapter...
Machine Performance
Annular Thickness, Annulus, and Annular Space; Overcut; Slurry or Auger System; Cutter Wheel Design and Select; Slurry Separation Plant; Buried Objects and Obstruction; Steering....
Submittals
The contractor should submit the items listed in the specifications for review and acceptance by the engineer. The submittals are generally divided into preconstruction and postconstruction...
Shafts/Temporary Structures
Shafts should be of a size to accommodate the equipment and pipe selected and to allow for safe working practices. If the shaft must accommodate the permanent works, it is the contractor's...
Construction Support Services
A preconstruction survey of existing structures within the anticipated construction zone of influence should be conducted before any construction begins. A plan for structures that need...
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