The Application And Numerical Analysis Of The Cement Injection Pile Composite Foundation

In order to enchance road embankment stability and control settlement deformation, cement injection pile composite ground is widely used to reinforce the embankment constructiond on soft siol. At present, some useful result of calculation theory and latest research on the embankment deformation have achieved. However, the character of DJM composite ground is very complex, the mechanism of the stress-deformation theory of DJM composite ground isn't thoroughly understood yet, and the number of uncertain influence factors of design parameter is too much to be considered. So there still exits much disparity between theoretical results and measured results.This paper associates the practice and researched results of DJM composite ground, two problems that have the special features is discussed, that calculating pile-soil stress ratio and method of ascertaining bearing capacity of composite ground. The stress ratio of pile-soil is an important parameter that reflects the work condition of composite foundation, and regulation of stress-deformation is complicated, up to now, a more perfect calculation mode is accepted by the engineering field. In this paper, an analytical formula for analyzing pile-soil stress ratio under the interaction of pile and soil is deduced, it provides a new way for the calculation of pile-soil stress ratio of composite foundation, and it provides reference to design composite foundation. Then through in-site experiment, the varying characters of pile-soil stress ratio and pile-soil load share ratio are analyzed, the analyzing results reflect pile-soil stress ratio educes with load increase, and the ratio does not change after it has reached minimum value, and pile-net composite foundations can be used to minimize the vertical and horizontal displacements of embankments on soft clay foundations. Also express pile-soil stress ratio are not constant, so we are designing composite foundation, we should consider various factor completely as far as possible, try to calculate with various methods, takes the reasonable value.Secondly, all kinds of determining methods for ultimate bearing resistance are discussed and analyzed, based on the field static loading test to determine the bearing capacity of cement injection pile composite foundation is a direct and credible method, but different bearing capacities may be given by different testers through the same test P-S curve. Hyperbola method can be used to predict the ultimate bearing capacity is proposed, a great deal of experimental data is contrasted and analysed, the result shows that Hyperbola method is an effective and assistant method.In the end, from engineerng practices, problems and mistake idea about composite foundation from design and constraction is illustrated, it is helpful for further theoretical and practical research work.