Transmission And Substation Foundations - Technical Design Manual (TD06088E)

DESIGN EXAMPLE 8 HELICAL PILE FOUNDATION FOR REMEDIATION

OF SUBSTATION BUS SUPPORT SYMBOLS USED IN THIS DESIGN EXAMPLE

ɸ ........................................................ANGLE OF INTERNAL FRICTION 7-43 γ ............................................................................ UNIT WEIGHT OF SOIL 7-43 N................................................................................. SPT BLOW COUNTS 7-43 PC........................ALLOWABLE DESIGN LOAD IN COMPRESSION 7-45 P t ......................................ALLOWABLE DESIGN LOAD IN TENSION 7-45 FS..............................................................................FACTOR OF SAFETY 7-45 Q t ...................................................................ULTIMATE PILE CAPACITY 7-45 K t ........................................................... TORQUE TO CAPACITY RATIO 7-45 A...........................................................................AREA OF HELIX PLATE 7-45 N c ............................................................BEARING CAPACITY FACTOR 7-45 T........................................................................................................ TORQUE 7-45

DESIGN EXAMPLES

Purpose This design example is intended to assist with the remediation design of a substation bus support that has settled. The plan of repair is to replace the central drilled concrete shaft beneath each leg with two type RS (Round Shaft) piles with a steel grade beam. The central concrete shaft will be demolioshed as well during pile install. This example will show how to calculate the axial capacity of the type RS piles and the lateral capacity of the type RS pile, using L-pile. After the loads for the structure have been determined, it is possible to design the piles.

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