| Geosynthetics enclosed stone columns is a semi-rigid pile used for soft foundation reinforcement.It has drainage consolidation,compaction replacement,improved foundation bearing capacity,control of foundation deformation,corrosion resistance,good environmental protection,low cost,etc.The advantages can be widely used in super soft soil,saline soil,liquefiable silt,wetland protection area and other soft foundation reinforcement.At present,the bearing mechanism,failure mode and stability failure mechanism of single piles treated with the piles are studied and discussed.The strength of the single piles of geosynthetics composites is limited by the strength of the geosynthetics and the characteristics of the foundation soil.The influence of the calculation method of single pile bearing capacity considering these factors needs further research;the geosynthetics enclosed stone columns has certain bending capacity and deformation adaptability,and how to consider the contribution of its bending resistance to composite foundation stability calculation method needs further research.Based on the experimental,theoretical analysis and numerical simulation methods,this paper studies the bearing capacity of the pile under the vertical load and the stability of the composite foundation under the embankment load.The specific research contents and results are as follows:(1)Combined with laboratory tests and numerical experiments considering the interaction between geosynthetics and stone columns,a unit test was carried out to reveal the failure mode and strength formation mechanism of the pile unit,The finite element calculation model of soil-geosynthetics-stone column interaction is established.The interaction between soil-geosynthetics-stone column is studied,and the bearing mechanism of geosynthetics enclosed stone columns is proposed,and the failure mode and bearing characteristics of gosynthetics enclosed stone columns are revealed.(2)Based on the numerical calculation results and the bearing mechanism research,the interaction mechanism of soil-geosynthetics-stone column is analyzed by theoretically,and then the calculation model of soil-geosynthetics-stone column interaction is established.The calculation method of pile strength considering the restraining action of soil and geosynthetics,the calculation method of bearing capacity of single pile and the calculation method of the tensile force of geosynthetics according to the upper load are proposed.(3)MATLAB software was used to compile the calculation program of ultimate bearing capacity of single pile and the tension of geosynthetics,and calculate the ultimate bearing capacity of single pile and the tensile force of geosynthetics under different tensile strengths of geosynthetics,revealing the distribution of tensile strength of geosynthetics.Considering the assumption of theoretical formula may cause calculation deviation,The finite element model of tensile strength of different geosynthetics materials and undrained shear strength of different soils is established,and the ultimate bearing capacity of piles is calculated.The theoretical calculation formula of ultimate bearing capacity of single pile is corrected according to the comparison between numerical calculation results and theoretical calculation results.(4)Modeling of 3D geosynthetics enclosed stone columns composite foundation embankment slope model by ABAQUS.The failure mode of geosynthetics enclosed stone columns was studied when the embankment was unstable.A method for calculating the stability of composite foundation with geosynthetics enclosed stone columns considering the bending strength of piles is proposed. |
