INTRODUCTION

TO

TRANSMISSION LINE

By

NITESH KUMAR SINHA

Training Program

On

Concepts for Foundation design of Transmission Line

Steps in Foundation Design

Foundations are designed for following forces• Stability Analysis

Stability Against Overturning Stability against Uplift Stability against Down Thrust Stability against Side Thrust

• Strength Design: Consist of Proportioning the component of the foundation to the respective maximum moment,shear, pull and thrust or combination of above.

• The controlling design loads for four legged lattice towers are vertical uplift,compression and side thrust.

TYPES OF FOUNDATIONS

Depending on GWT and type of soil/rock foundations classified as :

Normal Dry Soil Foundation Water table is below foundation level soil is

cohesive up to full depth with clay content of 10 to 15%.

Wet Soil Foundation Water table is above foundation level and up to 1.5

m below G.L e.g.paddy fields.

Partially submerged foundation Water table at a depth between 1.5 m &

0.75 m below G.L, soil is normal and cohesive.

Fully submerged foundation Water table is at 0.75 below ground level

soil is normal & cohesive.

TYPES OF FOUNDATIONSBlack Cotton soil foundation Cohesive soil, clay % more than 15% with high shrinkage & swelling property.

Partial B.C.Foundation Top layer of soil up to 1.5m is B.C. then it is normal dry cohesive soil.

Soft Rock/ Fissured Rock Foundation Hard gravel without blasting, under cut foundation.

Hard Rock Foundation Blasting required

Sandy Soil Foundation Sandy soils with clay content less than 0 – 10%.

Different types of Foundations

Different types of Pile Foundations

Stability Against Overturning

• H

Stability against Uplift

Stability against Down Thrust

Stability against Side Thrust

DESIGN

THANKYOU

END