The Research And Application Of The DJM Pile's Bearing Capacity And Its Parameters Backward Analysis

The Dry Jet Mixing(DJM) pile's bearing capacity and deformation behavior are studied by way of Field test and theoretic analysis. Two groups of field tests on original soil and the soil among piles ,three groups of field tests on single pile ,one-pile and three-pile composite foundation have been conducted and the results of the bearing capacity ,as well as the elastic modula of each pile and composite foundation are obtained.It can be seen that soft earth reinforced by cement-soil piles seem to have better appearance in bearing and deforming than original one.The strength and elastic modulus of soil is obviously improved. The stress ratio n is also measured during the process of the field test.Its value varies from 6.2 to 9.6. Applying the elastic model to piles and soil layer,elastic-plastic model to soil and two-dimensional finite element method to the analysis of composite ground,the load transfer anddeformation behavior for composite ground is discussed.When the applying load is smaller than the proportional one ,the deformation varies within linear-elastic.Theoretic curve calculated by FEM is analogous to the actual P-S curve according to field tests, the stress ratio n between pile and soil calculated by FEM can reflect the actual status during the field test.The numerical calculation show that load transfer and settlement of composite groundsill is affected by the thickness and modula of soil layer .Artificial Nueral Network(ANN) is an information treatment system that simulate structure and function of brain.It has been applied in many fields for its good characteristics that is lack in other methods.A backward analysis model based on neural network is built,which can be used to obtain mechanics parameter of cement-soil pile.The research about using neural network in backward analysis is talked and is proved to be feasible in this thesis.Finally,an engineering example is analyzed by nueral network backward analysis method.The precision of material properties it caculated can reach a high level.