Numerical Analyses And Experimental Studies Of The Vertical Bearing Behavior Of Bored Piles With Concrete Segregation

The topic of this paper is a part of the National Natural Science Funds Project—"Vertical Bearing Behavior Research of Bored Group Piles with Defective pile"(project number: 50978182).Pile foundation engineering which includes segregation defect of concrete is a common phenomenon. The reason, detection, prevention and cure of segregation defect of concrete are main objects that are researched now. Bearing behavior and mechanism of the defect are rarely discussed. Based on the background, the paper analyzed the vertical bearing behavior of single pile with segregation defect of concrete. The paper used numerical analysis and ABAQUS to discuss the vertical bearing behavior of single pile with different segregation degrees, positions and lengths. In aspect of numerical analysis, the paper developed two different numerical analysis methods by means of self-developed FEAPPF-3D program and ABAQUS software. Concrete segregation defect was simulated by Duncan-Chang model whose parameters were determined by combining the properties of gravelly soil and concrete soil in the program. Depth effect was also considered. Concrete segregation defect was simulated by Modified concrete plastic damage model in ABAQUS software whose parameters were determined by combining the properties of C30 concrete and mortar model test. The paper analyzed the influence of concrete segregation defect length to load settlement graph, frictional resistance of pile-side, pile-end resistance, vertical additional stress of soil. The paper educed some useful conclusions for Practical engineering through the comparative analysis of two methods.In aspect of modal test, the material property of sand, silt and mortar were tested. Based on the results, vertical bearing behavior of normal pile and defect pile were simulated in sand foundation. Pile was simulated by perfusion mortar. The paper analyzed the influence of concrete segregation defect with different position and fixed length to load settlement graph of a pile. Moreover, some related test phenomenon were observed among the test.