Model Test Study On Bearing Capacity Of Single Pile Bridge With Recycled Collapsible Loess Pile Foundation

With the development of our society's progress,the engineering industry in leaps and bounds,especially the development of Northwest China is more and more widely in the northwest,water bridged and cut paths through mountains have been verified.Northwest China belongs to the Loess Plateau.In the process of construction,the collapsibility of loess is a big problem,especially the bearing capacity of pile foundation,which is the purpose of this study.The collapsibility of loess is mostly tested by field immersion test.When the laboratory test is carried out,the related properties of disturbed collapsible loess will change,In order to study the plasticity of the loess collapse on the bearing characteristics of the bridge pile foundation research,in this paper,relying on the collapsibility of loess research on the influence law of bridge pile foundation of scientific research projects,through the indoor test,indoor model test and numerical simulation method of the combination of methods are analyzed.The test results and the conclusions are summarized as follows:(1)The physical and mechanical properties of perturbed loess were studied by laboratory test.The optimum moisture content,maximum dry density,liquid plastic trap and internal friction angle and cohesion of soil were obtained.Through the loess collapsibility test,the relationship between the collapsibility of the soil and the water pressure,the compaction degree and the water content of the disturbed soil is obtained.According to the results and the soil condition,the appropriate initial moisture content and compaction degree are selected as the follow-up Indoor model test foundation.(2)The influence of remolded collapsible loess on the ultimate bearing capacity and friction distribution of concrete single pile bridge foundation was studied by indoor model test.Based on the similarity principle and dimension analysis,the model pile was fabricated with high size H = 650 mm,Diameter D = 80 mm.Through the arrangement of the test elements,the distribution of the axial and friction of the pile and the settlement of the soil and the settlement value of the pile are obtained,and the corresponding relationship curve is drawn according to the results.The collapsible loess is analyzed for the bearing Mechanical properties.(3)Through the experimental study on the vertical bearing model of the pile-soil system under the condition of immersion and immersion,the ultimate bearing load of the pile foundation under the two working conditions is basically the same,but the settlement of the pile under the immersion condition is lower than that of the non-water When the pile settlement is much larger.(4)Through the experimental study on the negative friction resistance of the pile,the negative friction resistance of the pile-soil system under the condition of the first loading is in the upper part of the pile,and its distribution is "parabola".After the first flooding The friction resistance was "serrated",and the bearing capacity of the pile decreased obviously.(5)Based on the effective stress method,ABAQUS / Stander finite element software was used to simulate the indoor model test.The model of displacement and stress cloud of the pile and soil system during the loading and flooding were obtained and the variation law was analyzed.Through the numerical simulation and the comparison of the indoor test results,the ultimate load of the pile foundation and the negative friction resistance of the pile are basically the same,and the numerical simulation results further verify the reliability of the indoor test.