Proceedings - 13th International Workshop on Micropiles - 2017, Vancouver, BC, Canada, (ISM, DFI, ADSC)
Loading Effects on Battered Micropiles Supporting Lateral and Compression Forces
John R. Wolosick, P.E., D.GE and Robert F. Scott, Jr., P.E.
The use of battered pile foundations has gone from being ‘in-vogue’ to ‘verboten,’ in particular for seismic design, during the 20th century. This flip-flop in design and construction practice is examined in this paper. There are several reasons for these changes. In particular, popular pile types have changed significantly over the years. This paper examines the reasons for changes in practice affecting the use of battered piles and in particular looks at the effects of compression and lateral loads on micropiles. Micropiles have small cross-sectional areas. They also have limited resistance to lateral loads and bending moments when installed in vertical configurations due to their small diameters. Therefore, using micropiles at a batter can be particularly advantageous to carry lateral loads. However, using battered micropiles indiscriminately, without understanding the effects of soil loading on the piles and the impacts of increased foundation stiffness, can lead to unsatisfactory performance of the foundation system. Analysis methods for evaluating battered pile foundations vary and some common design methods may be incorrect. These errors could lead to yielded piles in service – particularly for uncased bar or hollow-bar micropiles. This serious concern is discussed and methods of correcting this common problem are presented. Moreover, this paper discusses the compression and lateral loading induced forces on battered micropiles used for foundation support.
|article #2623; publication #1033 (ISM- 2017)|