The Static Loading Tests And Mechanical Analysis Of AM Bottom-enlarged Grouting Piles

With the rapid development of high-rise buildings and large rail transit projects, theusing of piles have been increased and the engineering requirements for the bearingcapacity of piles are becoming more and more high. Thus, improving pile bearingcapacity and reducing the cost of piles become the main goal of the pile foundationtechnology development. The expanding bottom is a kind of effective means toimprove the performance of single pile bearing capacity. A series of researches havebeen done in China on the bottom-enlarged grouting piles. A construction methodnamed AM is a kind of ideal mechanical construction technology applicable tovarious kinds of pile foundation engineering. The geological adaptability of AMconstruction method with hydraulic control is strong and can be applied to most kindsof complicated geological conditions. The construction speed is fast with high pilequality. It has good technical and economic benefits. So, the study of mechanicalproperties of AM bottom-enlarged grouting piles has important practical significance.Based on a practical project, AM bottom-enlarged grouting piles’ mechanicalproperties are studied by using static loading tests and finite element software analysis.Firstly, the process of static loading tests is optimized. The problems that needattention in order to ensure the quality of test piles construction are pointed out, andsome reference to the views of similar pile tests are given out. Then, a reliable datacollection methods is chosen to analyze whether the pile’s ultimate bearing capacitycan meet the design requirements or not. The axial force of pile is measured by usingsteel stress meter. The distribution of the pile side friction according to the measuredresults is ultimately determined.The constitutive relation of the soil is selected according to the project. A relativelyaccurate finite element model is established using ANAYS for analysis andcalculation. The comparison between test and finite element model are made. Thenumerical model is used to simulate the pile compression process. Theload-settlement relationship of the pile is analyzed, and contrasted the differencebetween equal diameter pile and bottom-enlarged pile. The mechanical properties ofexpanded bottom are analyzed. Finally, a comprehensive evaluation of the pile aboutmechanical properties is given by combining test results and the finite element modelcalculation results. Some suggestions to AM bottom-enlarged grouting pileconstruction are given out.