Settlement Behaviour Of Single Piles Under Cyclic Loading

On the condition that there is no design approaches for the pile settlements of large-scale industrial workshops with gantry cranes, an efficient method to analyze this kind of settlement has been proposed. Based on field investigations, model tests, laboratory tests and numerical analyses, a reasonable theory frame has been created to explore the settlement mechanism of sigle piles under cyclic loading induced by gantry cranes and related control methods.The pile foundation of workshops with crane is subjected to not only the dead load of the building and the crane, but also the cyclic loading from the operating crane which is generally larger than the former one and has high loading frequency. There are many factors influencing the settlement behaviour of piles, such as features of the foundation soils, pile lengthes, relative stiffness between pile and soil, load levels and load durations. Therefore, it is very difficult to describe the complex interaction relations between pile and soil, especially the settlement regularity under cyclic loading only based on current theoretical analysis.The study starts from the experimental research, with the support of numerical simulation, and then extends the achievement to the engineering design, application and many other aspects. The main research contents are expressed as follows: the load regularity of the crane in workshop has been investigated; then a simplified calculation method is proposed to reflect the behavior of this kind of cyclic loading; the model test for the settlement of single pile under cyclic loading has been conducted by using a specific test system which is developed individually; the settlement mechanism of single pile under cyclic loading has also been analyzed by using a GDS triaxial apparatus; then a numerical model for single pile under cyclic loading has been established with a commercial finite element code ABAQUS to perform numerical analysis; finally, a design method for controlling the settlement of pile foundation under gantry crane cyclic loading has been proposed based on the results of the previous tests, numerical analyses and PBD methods, as an effective supplement for current design approach.The research has discovered the settlement mechanism of the pile foundation under cyclic loading of gantry cranes and made up for the deficiency of current design approach. Thus, a reliable and convincing theoretical basis has been provided to improve the safety of large-scale industrial workshops with gantry cranes.