The Engineering Performance Of The Lime And The Lime Pile Composite Foundation Finite Element Analysis

Engineering properties of lime-loess and FEM analysis oflime-loess pile composite fOundationAbstractLime-soil pile composite foundation is a simple. economical and effective method for treatingcollapsibIe loess foundation, which has been wildly used in engineering practices. But the theory studyabout lime-soiI pile composite foundation fa1ls far behind the engineering practice. So, In this papef,the basic behavior of lime-soil and the bearing mechanism of IiIne-soil piIe colnposite foundation areexpIored.As has been testified that the emphasis should be the strength (or stiffness) of pile materials toimprove the bearing capacity and to reduce settlement of composite foundation. By doing so, the upperload can be transferred by pile to deeper and more spacious subsoil below tl1e foundation. By doinglaboratory experiments, the strength of the lime-soil mixture and its factors are studied. At the sametime, the engineering properties of lime-loess including compaction. shear and compression areanalyzed. Results show that lime content affects evidently the engineering properties of lime-loess andwater content also is an important factOr influencing the engineering properties of lime-loess, and thatcuring time affects compression and shearing property notably. Many parameters such as optimumwater content. maximum dry density. maximum cohesion and maximum internal friction angle and theirvariation rule are reached. Furthermore the variation rule of shear and compression property with thecuring time is given. As is determined that the engineering properties of lime-soil are best wl1enlime-soil ratio is 2.5f7.5. Next, some advice is present fOr constructor and designer.The actual effect of Iime-soil pile composite fOundation after two years is studied. ResuIts showthat the behavior of pile is enhanced and the collapsibility of the loess between piIes is e1iminatedfundamentaIly. The compaction effect of artificialIy drilled lime-soil pile is not obvious comparing testresults of soils between piles at different position. Furthermore the shear property of soils between pilesis studied.Finally, the behavior of lime-soil pile composite foundation is researched by means of FEMnumerical analysis using the basic parameter obtained through laboratory tests. These behaviors includecritical length of pile. pile-soil stress ratio. superimposed stress and so on. For Iime-soil piIe compositefoundation under vertical load there is a critical length of pile. The critical length of pile increases withthe diameter of pile. Additionally, but the lime-soil ratio and method of drilling hole don抰 affect the critical length of pile much. The stress concentration in the composite foundation is still significant, and the bearing capacity of the soil between piles is improved. By changing the parameter of pile and soil, the influence of lime-soil ratio and method of drilling hole on the behavior of composite foundation is studied. The conclusion is reached that the lime-soil ratio less affects the superimposed stress and the stress of pile and soil, but which is affected by the means of drilling hole.