Static Load Test And Simulation Study On Bearing Capacity Of Large Diameter Rotary Digging Pile

Pile foundation has been widely used in the construction of highway bridges, it occupies more than one third of project cost.The stability and durable of pile foundation has same significance with its economy. The field load static test is the most intuitive and effective method for the optimization design of pile foundation,however the ultimate bearing capacity of large-diameter piles usually can not be study by vertical static load test.,how to research its ultimate bearing capacity according to the incomplete test data is of great importance in practice,this paper relies on field load static test of Huangling-Yan’an highway expansion project, uses modified Grey Theory Prediction Model and Fem software ABAQUS6.12 forecast and analysis the large diameter piles of this region, research work are as follows:(1) Test pile is designed as engineering piles design criterion and field load test is carried out in weak collapsible loess foundation,test date is collected and preliminary analysis is proceeded,then summarizing bearing properties of large diameter pile in this region.(2)Combining with measured data, common Q-s curve prediction method is compared to GM(1,1)gray model which was ran by MATLAB to predict the ultimate bearing capacity of previous test pile. Choosing modified GM(1,1) which has highest accuracy to predict the ultimate bearing capacity of pile of this test after comparing forecasting precision.(3)On the basis of measured data,Fem software ABAQUS is applied to build 3D model of static load test which considered uplift load of anchor pile, the rationality of the simulation calculation model is verified by comparing simulation results with measured data.(4)Researching influence of setting mode of anchor pile impacted on the ultimate bearing capacity determination of test pile, recommending the best anchor pile setting for static load test.(5)Carrying out simulation analysis of all factors such as soil parameters, pile-soil contact interface parameters and pile parameters which influence the ultimate bearing capacity of pile, summarizing its influence rules such as size effect and effective length.