Trenchless Technology

1. INTRODUCTION

Trench less technology is basically making a tunnel below the surface and staling service lines like water or gas pipes, electric or telecommunication cables etc. without any disruption to the public. It also makes it possible to install the utilities under rivers canals and other obstacles with no disruption of flow and with minimum or no damage to the environment. The difference between trenchless and other subsurface construction techniques depends upon the size of the passage under construction. If a subsurface construction does not permit human entry, it can be termed as trenchless.

The method is many times used without considering soil characteristics, overburden and the loads coming on the surface where the method is used. in case, the soil is sandy, water table is at shallow depth and heavy loads like that of urban traffic is expected, the depth of trenching has to be at a depth that the pressure of the load on the surface does not affect the bore else surface caving in cannot be ruled out. Therefore, sufficient precautions should be taken in loose and sandy soil strata, particularly near the ends from where the trenching is started or ended. Traditional open trench method seems ineffective for present requirement like under roads, railway tracks, highways, sewers, drains, cables etc.Without any disruption to traffic as it is not necessary to dig up or cut across the road. Other obstacles encountered in adopting these old methods are described as follows:

➢ Obstructions on roads, busy areas diversions have to be provided before start of digging of work and entailing avoidable expenditure.

➢ The cost of fuel as well as additional time wastage is huge over the total period of construction though not directly attributable to project cost.

➢ Cutting dip trenches in congested areas, cracks appear on the adjacent buildings resulting in stay orders.

➢ Damage cost to other service lines/cables present in...