TRANSMISSION LINE TOWER FOUNDATIONS. 1)DESIGN OF FOUNDATIONS. 1. TYPE OF LOADS A--COMPRESSION OR DOWN WARD THRUST B--TENSION OR UPLIFT C--LATERAL FORCES OR SIDE THRUST BOTH, TRANSVERSE AND LOGITUDINAL DIRECTIONS. 2) SOIL PARAMETERS . A-- LIMIT BEARING CAPACITY B-- DENSITY OF SOIL
To be used for locations where normal dry cohesive or non-cohesive soils are met .Foundations in areas where surface water encountered from rain runoff or agricultural fields (except paddy fields ) shall also be classified as normal dry.
To be used for locations :
a) Where subsoil water is met between 1.5metres and the depth of foundation below the ground level.
b) Which are in surface water for long period with water penetration not exceeding one meter below the ground level e.g. paddy fields.
To be used at locations where sub-soil water table is met between 0.75 meter and 1.5 below the ground level.
To be used where sub-soil water table is met at less than 0.75meter
To be used at locations where soil is clayey type ,not necessarily black in colour, which shrinks when dry and swells when wet ,resulting in differential movement .For designing foundations ,for such locations ,the such locations ,the soil is considered submerged in nature.
To be used at locations where decomposed or fissured rock ,hard gravel ,kankar ,limestone laterite or any other soil of similar nature is met .Under cut type foundation is to be used for fissured rock locations.
In case of fissured rock locations ,where water table is met at 1.5M or more below ground level ,wet fissured rock shoul be adopted
Where fissured rock is encountered with subsoil water table less than 0.75M below ground level, submerged fissured rock foundations shall be adopted.
In case of dry locations dry fissured rock foundations shall be adopted