Latest technologies used to save time, cost and efficiency

Subsurface infrastructure construc­tion and maintenance activities are fraught with uncertainties which, if left unaddressed, could lead to time and cost overruns resulting in lower efficiency on most of the fronts, if failures are encountered. Uncertainties like existence of unknown subsurface structures, sudden alteration of the soil/rock media quality, presence of groundwater are some of the few examples that require adequate attention during project planning and execution. In addition, presence of above-ground structures is a major impediment in project progress and many a times leads to delays, increased project costs, and lower efficiencies. Trenchless Technologies for developing, maintaining and managing subsurface utility networks provide a viable option for constructors to save time and cost, and enhance the overall efficiency.           

Trenchless is a family of construction methods used to develop, maintain, and manage subsurface networks remotely without excavating continuous trenches. As these techniques help in alleviating need of trenching surface destructions are reduced. Further, as these are executed remotely, complete execution chronology is properly designed addressing the uncertainties to a great extent. Both factors lead to savings on time and enhanced efficiencies. These techniques are ever developing with newer equipment materials, & consumables enabling the constructors to arrive at a state-of-art solution for each given challenge.             

Trenchless is used for construction of new subsurface installations, and rehabilitation, & replacement of existing subsurface utility networks. Common methods used in India include Horizontal Directional Drilling, Pipe Jacking and Microtunneling & Pipe Jacking, Tunnel Boring, and several similar methods for new installations, GRP Lining, Cured in Place Pipelines, Machine Wound Spiral Linings, and several similar methods for rehabilitations, Pipe Bursting for replacements. Primary concept of trenchless is to create a continuous subsurface cavity remotely that is protected by a casing / lining pipe, if it is new installation, strengthening the existing liner by strengthening it, and in case such strengthening is not practical, replacing the liners.           

As per the definition, trenchless is a remotely controlled construction methodology, and lack of information of subsurface strata, and the existing structures therein, may lead to accidental damages to existing structures during the project execution. If the constructor is aware about the strata of the project battery limits, he or she could plan and execute the project successfully by avoiding conflicts with them. Subsurface surveying, therefore, is an important part of decision and execution process. This surveying provides accurate knowledge of subsurface/underground/buried utilities (pipes/ cables/ drains etc.) existing in the battery limits of the project. This surveying is the critical part of such works, that ensures savings on Time, Cost and enhances efficiencies, and termed as Subsurface Utility Engineering (SUE). SUE is an upcoming field dealing with procedure and standards for detection and mapping of underground utilities using geophysics. The advantage of a geophysical survey is that it enables information to be obtained for large volumes of ground that, due to cost, cannot be investigated by direct methods. The use of geophysics in Indian trenchless projects has been maturing over the past few years. Major construction projects often use geophysics to image the sub-surface along the proposed route to detect changes in soil and rock stratigraphy, locate buried utilities and map fracture zones. The ability of geophysics to mitigate risks associated with unexpected delays has often resulted in significant cost savings. Variety of geophysical complementary methods are employed on trenchless projects. Various techniques, such as ground penetrating radar (for shallow stratigraphy and the detection of buried utilities); seismic refraction (to map the soil-bedrock interface and determine the mechanical strength of the subsurface); electrical tomography (to map water-saturated zones, faults and fractures); and seismic reflection (deep investigations for faults, fractures and shears), are available for providing quick information on subsurface conditions. Use of these techniques ensures proper equipment selection, minimum equipment downtime, and resulting saving on projects.      

Indian Society for Trenchless Technology (IndSTT) is the apex organization to promote trenchless technology in India. It has prescribed guidelines, schedule of rates, codes of practice, and other related inputs essential for the application of trenchless technology.

For the overall sensitization it also organises several events, out of which NoDig India Show series is one of the major annual events. Readers can get an in-depth information from its website www.indstt.com

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