Most common model of transmission line system is for terminal model .Construction of Transmission line is very hard and sophisticated method . Major concern take on safety side while constructing and operating transmission lines. 10-30% of overall cost for construct transmission tower is take to form the foundation of power transmission tower.Transmission line traverse across different part of the country in different environmental conditions.
There are several methods use to design the transmission line on selected terrain. PLS Cad is one of the powerful and most used software’s by Transmission design engineers and there are other GIS base softeners are also helpful on this process of designing. There are several types of tower foundation according to geographical change in that appropriate land.
1. Good soil
Concrete block are use to cover any part of steel work below the ground and this foundation is intended to be used where the soil conditions are fine and water is also under side of that foundation.
2. Poor soils
These types of foundation conditions were suitable for weak soils. This foundation is also intended to be used where the soil conditions are fine and water is also under side of that foundation
3. Water logged
These types of foundation conditions were suitable for location where good soil is encountered at underside of foundation level. An example for water logged is paddy field with good underlying soil.
4. Raft Type
These types of foundation conditions were suitable for location for installation in poor soil in an area which is regularly waterlogged.
5. Well Types
These types of foundation conditions were suitable for use in poor soil in area which is permanently water logged. We can assume that line shall be sunk and the foundation would be sunken so the foundation would be designed to carry loads.
6. Soft Rock type
These types of foundation conditions were suitable for location where soft rock occurs .The soft rocks shall be weathered or of harder in nature.
7. Hard Rock
These types of foundation conditions were suitable for installation at location where good rock is encountered .
8.Cohesive Soil
Normally this soil have the combination of silt and clay . This soil also get unified with the parent soil.
8. Pile Foundations
Where deep swampy or other type of ground is encountered unsuitable for above decide foundations, pile foundations, pile foundations shall be employ.
Apart of the above mentioned soil types, different combinations of the soils are also able to aplly while excavation of Transmission line tower foundations.
Foundation perform key role in any structure in safety and performance. If we consider about transmission line we have to extra care on it foundation rather than other structures. Density of Soil, Angel of earth frustum and Limit baring capacity of peculiarity soil are the major parameters for soil where need to consider designing transmission line foundations. Pre cast concrete and pile driving become necessary where the soil of a certain ground is poor.
There can be so many transmission tower foundation types which not mentioned in here. and Location to location those foundations types can vary.There are several guidelines to flow while construction transmission line towers in different soil conditions.