Proceedings of DFI-India 2019: 9th Conference on Deep Foundation Technologies for Infrastructure Development in India, (DFI)
Effect of Elastic Non-Linearity of Soil and Pile on Uplift Capacity of Transmission Tower Foundation
Manish V. Shah, Ph.D., Usha K. Patel, Ph.D. and Purav A. Raval, BE
The transmission line tower foundations are subjected to significant uplift loads during its design life due to damage forces, wind forces and conductor tensile forces acting on the super structure. In India the transmission towers are designed and tested as per IS:802:1995(2006).The IS:4091:1979 provides guideline for design of foundation for transmission line structure. Present study is an attempt to determine load-settlement characteristics of model tension transmission tower of 220KV capacity embedded in silty-sand deposits using bored cast-in situ pile of L/d ratio 4,6 and 8( where L= length of pile , d= diameter of pile). The uplift capacity is determined using specialised fabricated tension load frame of 10T capacity. The experimental procedure includes determination of index properties and engineering properties of field soil, casting of concrete piles, fabrication of model tower and load tests on tower-foundation system. The load response of tower-foundation system towards different loads and displacements was analysed. The lateral load-displacement curves were obtained using test data. The vertical displacement and settlements were measured to obtain ultimate load carrying capacity of foundation .The effect of L/d ratio on the ultimate capacity of foundation and differential settlement was analysed. Using Bromís method for short pile in cohesionless soil the ultimate soil resistance per unit length was determined for each slenderness ratio of the pile . For every failure load the pile displacements and rotations were obtained. The shear force and bending moment distribution at the failure were obtained along the length of pile.
|article #3286; publication #1059 (India2019)|