Numerical Analysis Of T-shaped Deep Mixed Soil-Cement Columns Supported Embankment

In recent years,many construction projects have grown up tremendously,especially those related to transportation infrastructure such as high-way,high-speed railways,etc.Meanwhile,the design of those structures is required to be sustained with external load,its foundation also plays a key role to stabilize the main structure and keep the work performed during their service life.A considerable number of such projects are found to lie in the soft soil stratum,usually known as the weak foundation concerning settlement problems.From the point of view of geotechnical engineering,various techniques are employed to improve the physical and mechanical properties of naturally weak foundations.These techniques are focused on not only the methodology of ground reinforcement but also the economical optimization of project costs,which cover the material use,construction technique,and construction time,etc.T-Shaped deep mixed column technique is first developed in china to improve the existing conventional deep mixed column method where the upper part of the column is enlarged in the shallow depth.In this study,three-dimensional slice column models and the simplified 2D plane strain model are used to evaluate the performance of the T-shaped deep mixed columns which are arranged in a triangular pattern to support an embankment of a field test by using the finite element software Plaxis 3D and Plaxis 2D 8.2.Furthermore,after the validation of the numerical model,a series of parametric studies are carried out to investigate the influence factor on the performance of the T-shaped column.The investigated influence factor includes embankment modulus,embankment height,column modulus,enlarge depth,upper column diameter,and column shape factor.Base on the result of numerical model and parametric study,the major finding of this research will be summarized below:(1)The numerical model is reasonably simulated the investigation of the TDM column supported embankment compare to the data of field investigation.From the numerical analysis,the ground settlement measure after the construction(290 days)has been reduced by about 46% of the untreated soil.In addition,adopting the equivalent area method to convert the 3D problem of the TDM columns,which are arranged in a triangular pattern to a 2D plane strain model,is acceptable,plus time-consuming.(2)The 3D and 2D parametric studies were conducted to investigate the influence factor on the performance of the TDM column supported an embankment.The study indicates that,the degree of influence of column modulus and embankment height on soft soil settlement is quite high,whereas the other factor is low exclude enlarge depth that the degree of influence is medium.The degree of influence of each factor on the differential settlement is relatively high,exclude the enlarge depth and embankment modulus.Moreover,the influence of the column shape factor becomes more significant in consideration with embankment modulus and embankment height.Besides,in consideration of degree influence,these influence factors have low influence.