Trenchless Technology in Construction and their Methods
Neenu S K
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The concept trenchless technology is a word used to describe a set or family of activities that are employed in construction work or in civil engineering. The set of works involves activities or techniques for making holes or conduit renovation or underground activity without disturbing the surface.
Trenchless technology is widespread in various areas that involve techniques, equipment and methods or procedure that are unique for each project type.
Background of Trenchless Technology
The concept of trenchless construction method was started from 1900's. As time passed new method got added with new studies and innovation. The concept of no use trenches mainly during underground construction is to avoid problems and nuisance arising from subsurface disturbances.
We have observed that when a small underground conduit goes off, it has to be repaired by open trenches causing a nuisance to the locality. If a road moves through the area, traffic and inconvenience to the public are further problems arising.
In general, trenchless technology minimizes highway damage, environmental impacts, and traffic problems.
Features of Trenchless Technology
The technology includes the following features
Installation
Replacement
Rehabilitation
Inspection
Location and Leak Detection
This system provides all these features. Which feature to undertake, mainly depends on the type of project and the requirement. Whatever be the work conducted, minimum or no ground excavation is appreciated.
Need for Trenchless Technology
The demand for efficient community service in terms of both quantity and quality is increasing. This has been a continuous pressure on the heads of responsible ones in the areas of planning, the engineering, their implementation and on the maintenance.
Further increase of underground activities and the improvements with new innovations had increased the complexity.
There was a situation where all these underground activities were done only by means of open cutting or by excavation that would badly affect the natural flow of workplace of a highway, streets, railroads or buildings. The best alternative for this was the trenchless technology.
Many studies have shown the following advantages of trenchless technology in terms of costs. The cost involves the direct, indirect as well as the overall social costs. When we analyze a project handled by the trenchless method, the restoration costs are reduced to an extent or in some cases no restoration costs exist.
Compared to conventional methods, the trenchless technology employs less labor thus less labor cost. This method help in implementing simplified operation mainly in urban areas. An effective system of trenchless technology keeps good relations with the customers and welcome new customers.
On an overall trenchless method eliminates all the disturbances caused on the surface. When we employ an open cutting method instead of a trenchless method, the traffic is disturbed, extra restoration has to be done, and the surface has to be set back to its original condition. These are the reasons why trenchless technology is needed.
Trenchless Technology Methods
On an overall the trenchless technology methods (TT) can be classified into 2 main divisions:
Trenchless Construction methods (TCM)
Trenchless Renewal Methods (TRM)
The trenchless construction methods involve different techniques that are related to the commencement of a new work or new project in underground. It may be a new conduit or pipeline installation in the site or any other new utility.
The trenchless renewal methods that facilitate already existing utilities. It may be renewing or rehabilitation or renovation. This work is applied on old, existing utility or pipeline systems that may have some problem with their performance.
Trenchless Construction
Irrespective of the type of construction project, the trenchless construction or renewal methods depends upon certain factors or parameter. They are:
Type of application
Accuracy
Range of work in diameter
Maximum length of installation
The skills and technology experience of the contractors, engineers and the equipment operators, are one of the leading factors governing the accuracy of the project. Their knowledge and skill would help in determining the maximum length of installation for a clean project work.
The site conditions; surface and sub-surface conditions and the requirement of the project will let us know which and what type of equipment would suit the best. This would make a clear idea on how efficient the proposed trenchless method is for the site and requirement under condition.
These are later studied and investigated by engineers who are professionally forward in both the planning and the designing stages of the project.
Classification of Trenchless Construction Method
This method as mentioned involves construction and installation of new utility systems below the grade without the use of an open trench.
TCM is classified into two main broad categories based on work entry. They are:
Work entry required
Work entry Not required
The work entry required classification has two main techniques. They are Pipe Jacking (PJ) and Utility Tunneling (UT).The work entry required classification is mainly carried out by Horizontal earth boring (HEB).
The HEB techniques do not make use of any workers to work inside the borehole drilled. They are carried out by mechanical means only. Now as the classification tell, the PJ and the UT methods would employ workers inside the borehole. They facilitate the excavation and installation purposes.
Classification of Trenchless Renewal Methods
The trenchless technologies, to meet the purpose of renovation are still under development. These methods possess the key features to give a new life to an existing utility system. They can be used to:
Rehabilitate
Renovate
Replace
Enlarge pipe systems
Renew
Repair
The trenchless renewal method involves the following types:
Underground coatings and linings
Modified Slip lining
Close-fit pipe
In-line replacement
Cured-in-place pipe
Slip lining
Localized Repair
Lateral Renewal
Thermoformed Pipe
Sewer manhole renewal
The choice on which technique is best for renewal mainly depends upon the following factors:
The length of the pipeline system
Type, size, material of manholes
The number of manholes
The physical conditions of pipeline
The bends involved
The details of service connections
Once this is done, we need to identify the problem. The problem may be:
