Settlement Criteria Based On Equal Length Of The Pile Composite Foundation Design Method

With the urban rapid development of high-rise structure emerged. It requires a higher bearing capacity and smaller settlement to meet the upper structure of the security and stability. Many different ways exist to deal with the composite foundation in engineering fields. Long-short-pile composite foundation is based on the long-pile control settlement and short-pile improve bearing capacity of the ideological, in engineering practice has been widely used and achieved a good social and economic benefits. But as far as the long-short-pile basic working principle and practical understanding of the character was not thorough enough, so far few theories regard the settlement and capacity consideration, has not yet formed a unified better design methods and mature design theory. Based on field trail data of the long-short pile composite foundation, presented their viewpoints, main content as follow:1. Summarizes in the domestic and foreign related long-short pile composite foundation piles and piles of soil interaction mechanism integrating the entire construction process analysis pile length with the loading process of change and the effective length concept draw pile length proportional to the degree of play loading process.2. Drawing four piles the stress effect, and the use of more to the confining pressure of soil and the area between the four piles, derived soil between intensity coefficient play the upper and lower limits, drawing more stress pile maps draw a composite test side pile foundation of stress than the center composite foundation pile of stress.3. 2D consider the negative impact of friction, assuming pile side of the lower part of the friction area and the length of the upper negative friction piles area offset by the circumstances. Rigid application under the settlement guidelines, and other two were the length piles of design optimization methods. 4. According to a project site examples of actual test data, analyze the length of rigid composite foundation applied in practice results on the works of this paper, the method of calculating the actual test data were analyzed, and the necessary error analysis summary concluded, for the future of this type of foundation of theoretical study and practical design reference.