Study On Settlement Control Of Composite Piles Foundation

For some limitations, many engineers always use the conventional design method of piles in the work of piles design. The method believes the entire loads are subjected to the pile so as to bring large waste. Although combined action, which means the whole structural load is assigned to piles and caps or rafts in proportions with the elastic theory, between pile and soil is considered, it is different from the settlement control method of composite piles. And although the soil between single piles may bear over 50% of the whole load in composite piles, replacement ratio of piles is low. So the kind of foundation does not belong to the composite foundation. As a new type method for pile design, the settlement control design method for composite piles foundation has a board and bright future.Study completed in the paper includes:Composite piles controlled by settlement consider the distribution between piles and soil and the non-linear behavior which some or all piles can reach. So the settlement of this kind of piles can not be taken into account by the conventional elastic theory. In the paper, several analysis methods for settlement of the new pile foundation and its applicability are presented so as to apply to different soils.Safety factor of conventional pile foundation has been showed clearly in the code, but the code is involved into the settlement control design method for pile foundation hardly. In the paper, based on the present integral safety factor, it takes the combined action between piles and soil in the composite piles controlled by settlement. And the paper analyzes further that how to consolidate the safety factor of the two different material into the integral safety factor of composite foundation.The paper also shows the advantage and disadvantage of optimization method for general piles foundation and composite piles controlled by settlement from the optimum design for piles foundation. The design of composite piles controlled by settlement also meets with two basic requirements-the requirement of capacity and the requirement of settlement. The design method can be divided into "capacity control" and "settlement control". At last, with the projects conventional design method, "capacity control" design method and "settlement control" design method and procedures have been done. The result shows that composite piles foundation controlled by settlement can obtain better benefits and assure better security for projects.