Research On The Prediction Of Vertical Ultimate Bearing Capacity Of The Single Pile Of PHC Pile

Abstract：The rapid development of Modern industry and science technology, makingthe construction projects need high quality and efficiency, security and economic pilefoundation. PHC piles were a new type of prefabricating concrete pile. It had manyadvantages, such as large bearing capacity, better quality, simple technology and lowcost, so it had been widely used in geotechnical engineering during the recent years.This article focused on analyzing the impact of single pile ultimate bearingcapacity of the main factors, viewing the ultimate load-capacity as a gray system, andto study the gray system theory. As calculating the bearing capacity in accordancewith the empirical formula is generally lower, so the text used the extrapolated valuesby the gray GM (1,1), which was based on the specification’s control, established anonlinear computing power of GA-BP neural network model to predict the ultimatebearing capacity of single pile PHC piles. Based on the GA-BP neural networkcharacteristics, establishing a pile length, pile diameter, pile pressing force, pileembedded depth, the weighted average of the side friction, tip resistance, penetrationcoefficient and rest period, a total of8parameters as input layer neurons element, themiddle layer of neurons was a2N+1(N is the number of input layer neurons), outputlayer is a (vertical bearing capacity) of the8-17-1neural network model. Using themodel in a Fujian region’s58PHC piles to the sample training, and predicting eachsimulation of the other8PHC piles.The results showed the calculation and measuredresults matched well, and the error was less than5%, theoretical models could supportthe practical engineering. Finally, combined orthogonal experimental design method,using the above network capacity train the multi-factor value changes in forecastsamplitude to sentence the sensibility analysis of various factors, the order was: thepile diameter, the weighted average of the side friction, rest period, pile length, pileembedded depth, penetration coefficient and pile pressing force, according to thesequence in the area, we could draw the conclusion: the PHC pile was an end bearing pile, in the use of empirical formulas for calculating the bearing capacity, we couldselect the high-value range of side resistance value to solve the question; The resultalso could be used as the optimize theoretical basis, from design to construction, fromexperiment to operation management, from assessment to the improvement of theback-analysis process for PHC Piles.