Three Dimension Finite Element Analysis Of Alleviating Bridge Approach Settlement With Geogrid

Firstly, the harm and the origin of differential settlement of bridge—subgrade transition section are described and several useful treatments are compared. At the same time, recent developments on differential settlement in our country and on the world are presented. Secondly, the reinforced mechanism of geogrids is analyzed emphatically. Based on theoretical analysis, a three dimensional non-linear finite element program is developed to examine the effects of alleviating bridge approach differential settlement by emplacing geogrids in the backfill behind bridge abutment. After analyzing the character of stresses and displacements within backfill behind bridge abutments and the interfacial friction action between geogrids and fillings, mechanism of using geogrids to reduce differential settlement is obtained. Then, the thesis analyses the effects of some factors on the backfill behind abutment, such as arrange form of geogrids in backfill and join form between geogrids and abutment. Results show the settlement increases with the larger of the spacing of geogrids. In order to choice appropriate spacing, the budget and the settlement demand must be considered.The thesis indicates that differential settlement of bridge—subgrade section can be well controlled by using geogrids. The mechanism for geogrids to reduce differential settlement lies in that the shear stresses of geogrid-soil interface, occurring under axial compressive pressure, change the magnitude and distribution of axial and horizontal normal stresses in reinforced soil.Some inferences are provided for the similar engineering.