Time-related Increase Evaluation in Bearing Capacities of End Bearing Jacked Piles by a New Type of CPT
Yongqiang Hu1,2,Liansheng Tang3,4, Zhizhong Li5, Haitao Sang1
COMPUTER MODELLING & NEW TECHNOLOGIES 2014 18(12D) 103-109
1School of engineering, Sun Yat-Sen University, No. 135, Xingang Xi Road, Guangzhou, P. R. China
2School of civil engineering, Guangzhou University, 230 Wai Huan Xi Road,GuangZhou Higher Education Mega Centre GuangZhou, P.R.China
3School of Earth Science and Geological Engineering, Sun Yat-sen University, No. 135, Xingang Xi Road, Guangzhou, P. R. China
4Guangdong Provincial Key Laboratory of Mineral Resources & Geological Processes, No. 135, Xingang Xi Road, Guangzhou, P. R. China
5Guangdong Yongji building foundation Co.,Ltd, Shunde, Foshan, P. R. China
The time-related increase in capacity of displacement piles after installation(known as set-up) is caused mainly by the shaft resistance. But the shaft and base resistances are seldom considered separately in the set-up evaluation. The time-related increase in capacity depends on the mobilization degree of the shaft capacity at the end-of-jack(EOJ), though this mobilization is closely related to the bas resistance. In this paper, a series of field tests including the jacking installation tests, load tests of model piles and a new type of CPT with a total resistance sensor installed were conducted at the Pearl River Delta alluvial plain. The tests have found that there are three type of distribution curves between the ultimate total shaft resistance and the measured one: the ultimate resistance is greater than, very close to or less than the measured one, and set-up is obvious in the first one, while in the other two are not. This indicates the mobilization of the shaft resistance at the end of jacking installation affects set-up. According to the experimental study, a new evaluation method has been proposed and proved reliably by practice, in which the mobilization of the shaft resistance is considered.