| The soft soil in the Qingdao Jiao Zhou area has the characteristics of large water content,slow consolidation,and high compressibility.It is reasonable to use composite foundation to deal with such soft soil.Due to the application of rigid or semi-rigid piles in composite foundation,soil stiffness between pile and pile is different.The traditional method is to lay a thick layer of sand cushion on the surface of soft soil.However,with the increase of urban construction projects,sand sources gradually become scarce.If the construction of composite foundation can be completed by using geosynthetic materials in a shortage of sand sources,it will reduce the cost of the project to some extent.This article takes the dredged soft soil foundation treatment in the Qingdao Jiao Zhou Area as the research background,and takes the composite foundation reinforced cushion working on soft dredger soil foundation as the research content,through laboratory tests and MIDAS(Soilworks)finite element software to analyze the mechanical properties of reinforced cushion composite foundation,and to analyze the impact of the different conditions of composite foundation reinforced cushion consoliding the dredger fill soft soil foundation,so as to design the composite foundation with reinforced cushion and geosynthetic reinforcement technology in reclamation engineering application of soft soil foundation and to provide a theoretical basis for the future practical engineering.The main research contents and conclusions are as follows:(1)Through the indoor soil test,getting the moisture content、compressibility、void ratio、sensitivity of the dredger fill soft soil in the Qingdao Jiao Zhou area,which has the low soil consolidation degree and the low shear strength.This soil belongs to the late Holocene of the Quaternary dredged soft soil artificial treatment.As to this situation,using the composite foundation to treat the dredger fill soft soil foundation in the Qingdao Jiao Zhou area is reasonable.(2)This study is based on the analysis of the method using in the mechanical properties of reinforced cushion composite foundation,and establishing some numerical models by using MIDAS(Soilworks)finite element software,which are used to Analysis the mechanical properties of reinforced cushion on Composite Foundation in the situation of different loads(100kPa,150 kPa,250kPa)and different reinforcement schemes(one layer,two layer composite geogrid).The conclusion is the composite foundation reinforced cushion will not appear in the upper loads and deformation of reinforced layer in the upper part of the large load on the pile-soil stress ratio.(3)Through the indoor penetration test and the indoor compression consolidation test,The conclusion is getting the permeability coefficient of sand cushion,the compressibility coefficient and consolidation coefficient of non-reinforced dredger fill soft soil and reinforced dredger fill soft soil.which provides parameters for the simulation calculation of consolidation settlement.(4)The study establishes the consolidation settlement calculation models which are respectively in different conditions(non-reinforced sand cushion,geogrid reinforced cushion,reinforced geogrid cushion)and different reinforcement schemes(laying a layer,the second layer and the third layer composite geogrid),respectively carrying out one and two dimensional consolidation settlement calculation and analysis.The conclusion is getting consolidation degree,surface settlement and residual settlement variation of one-dimensional consolidation settlement,the dissipation of pore pressure,the total settlement of soil and the change law of consolidation degree of two dimensional consolidation settlement,this study can let us to know the composite foundation reinforced cushion on soft dredger soil composite geogrid is better than that of Geogrid and the reinforced sand cushion,and the laying of two layer composite geogrid is reasonable,the laying of three layer is bad. |
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