Static and Dynamic Analysis of Driven Piles in Soft Rocks Considering LRFD Using a Recently Developed Electronic Database

摘要

Lack of well-defined approaches to characterize soft rocks and the lack of methods for designing driven piles pertaining to soft rocks often lead to some challenges during design and construction. The design of piles in soft rocks are currently performed using static analysis methods, which were originally developed for soils. Understanding the current limitation of design of piles in soft rocks, a research is being conducted by the authors to firstly develop an electronic database containing the information on subsurface, pile, hammer, driving, dynamic, and static load tests of piles driven in soft rocks obtained from the Wyoming Department of Transportation. The database facilitates storage of quality data required for static and dynamic analysis and can be easily retrieved for future development of resistance factors for load and resistance factor design (LRFD) in soft rocks. Pile resistances estimated using static analysis and wave equation analysis program (WEAP) have been compared with those determined using case pile wave analysis program (CAPWAP). Performance has been assessed using statistical parameters, such as resistance bias (ratio of measured to estimated pile resistance) and COV, which will be used for developing resistance factors for different static methods and WEAP. Results showed that the static analysis methods were largely conservative and inconsistent in estimating the total resistances of steel H-piles driven in soft rocks. Although WEAP overestimated almost 60% of the total test piles, the mean estimation was extremely close to the measured pile resistance with a relatively low coefficient of variation (COV). The reliability of the design on soft rocks can be improved by the performing pile dynamic tests with CAPWAP analyses on greater number of piles.