The Analysis Of Soil Arching Effect In The Pile-supported Embankment

Piled embankments are an effective way to support the embankment fill on the soft ground. As the modules of the pile and soil are relatively different, the settlement between them is different and the shear stress will be caused in the embankment fill. As a result, some of the load directly goes to the pile head and the stress imposed on the soil is reduced. This effect is called the soil arching. In this thesis, combined with the National Natural Science Foundation (No.50908198), the soil arching effect was studied by model test, numerical analysis and theoretical analysis.The main achievement and conclusions are summarized as follows:(1) The advantages and disadvantages of different soil arching analysis methods were studied in detail.(2) A series of three-dimensional model tests were carried out. The stress reduction ratio and the vertical stress distribution in the embankment fill were studied in detail, and the differences between measured value and the calculated values of classical methods were verified, and the difference of the values between different measurements comes from different assumptions on faliure models.(3) The two dimensional and three-dimensional numerical simulations were used to study the soil arching effects. Based on the results, the stress reduction ratio, the equal settlement section height and the failure modes were analyzed in detail. It is shown that the failure modes are different for different embankment heights. For low embankment, the failure surface is vertical or slightly inclined which starts from the pile edge and goes through the whole fill height. For high embankment, in the two dimensional case, the failure surface is composed of triangular elastic zone, radial shear zone and passive zone and in three-dimensional case, the failure surface is a logarithmic spiral surface.(4) Based on the assumed failure surfaces, the simplified soil arching analysis methods for two-dimensional and three-dimensional conditions were presented. The results show that the given methods can produce reliable results as proper failure surfaces are adopted.