Researches On Load-bearing Characteristics And Engineering Esting Of Pile Afeter Compaction In Loessial Area

With the implementation of the Western Development policy，a large number ofhigh rise buildings are emergent in those loess areas latterly, which are located in thewest of China. At the same time, the upper structure load requests higher bearingcapacity and settlement of building foundation. In deep gravity collapsible loess area,the simple collapsible loess methods and single pile foundation design cannot meet therequirements of the design or construction. Recently the method of DDC combined withpile foundation has been used for ground treatment in the deep collapsible loess area;this paper aims to analyzing the compaction pile bearing characters and the measuringmethods of ground treatment, according the study of ground engineering of high-risebuilding in Tong Chuan. The main research results are as follows：（1）On the basis of predecessors’ research results, using load transfer method,carries on the reasonable simplified calculation, adopts Sato-transfer function to analyzethe relationship between single pile load and settlement in the tier of theory.（2）This article is studying load bearing properties, which adopts the method ofnumerical simulation, based on the static load test. By using ABAQUS software tosimulate the static load test, and then obtained the curves of load settlement, distributionof axial stress and pile side friction. Moreover, it calculated the bearing ratio betweenpile side and endpoint. By analyzing these curves, it summed up transport mechanism ofsingle pile. Qualitative analysis of pile-soil modulus ratio, pile length, pile diameterchanges on the influence factors such as load settlement of single pile, the influence ofthe axial force and lateral resistance distribution law.（3）Analyzing the element for soil compaction pile combined with the pilefoundation engineering for testing, and the test methods and test results, provides areference for similar projects. Soil test results show that the effect of elementelimination of the subsidence of soil compaction pile proves to be good. For two kinds of static load test and high strain dynamic testing method to determine single pilebearing capacity were analyzed, the applicability of the two methods are summarizedand the advantages and disadvantages. Through testing into a hole and pile bodycompleteness inspection results, and the construction quality control is considered to begood, and the pile low strain dynamic testing method is accurate, practical, and lowcost.（4）Through static load test results of engineering examples and the results ofnumerical simulation analysis, It was found that after compaction pile the ultimatebearing capacity design value proves to be conservative. This article adopts thenumerical simulation of single pile to optimize the design.