Research On Single Pile Vertical Load Capacity And Analyses With Finite Element Method

Vertical load capacity of single pile refers to the ability of single pile to bear from the upside construction and the maximum of it is defined as vertical ultimate load capacity of single pile. Of which the value is one of the most important segments in foundation engineering design, which is the key design parameters as well. According to the level of present load test researching, it is very urgent and worthy to study in the methods of loading test. In the course of studying and data comparing the traditional methods will be innovated and new thoughts will come into being.This article elaborated on the theories of testing vertical load capacity of single pile, such as the static load test theory, the dynamic loading test theory and its formulas deducing, and finite element method. In this thesis a test pile signed as 1# is the study object, and individually with the method of static load test, with the method of dynamic load test, and with the aid of finite element method the value of vertical load capacity of which is deduced and contrasted each other. Researching on those processes and results we can find that correctly making uses of dynamic method and finite element method is much more convenience than using static method and a suitable result will also be gotten. Following are the main conclusions of the thesis:(1) The static load test theory synthesized the mechanics theory and statistics knowledge, with the basis of which the static method collected the test data, draw the test curve, and deduced the vertical ultimate value. The characteristic capacity of the single pile was gotten basing on the vertical ultimate value, which contained enough safety factor and can be applied in the foundation engineering sufficiently. The shortcoming of this method is that huge labor power and material resources is needed to prepare, long time is needed to keep on, and a certain indetermination is needed to settle.(2) Not only the high strain test but also the low strain test has complete and integrate theory system, which has a great deal of superiority in practice. The key point of it is to analyze the parameters of the pile - soil structure system. So it is very important to apply the dynamic method extensively and collect amount of data involving the static test data and the dynamic test data. The finite element method should be applied in the contrasting process when it is necessary.(3) From the model set up with the finite element theory, the load - displacement curve like the static test curve could be obtained. According to the experiments of 1# bridge pile we easily found that the front part of the model curve is very close to the static test curve. It has been concluded that with the aid of standards of the foundation engineering we can conveniently get the right value of single pile vertical load capacity from the model curve. This method is effective and should be going deep into studying.