Study On Stress And Stability Of Retaining Structure Consisted Of Pile And Retaining Wall

The usage of combined retaining structure(CRS) composed of the anti-slide pile and gravity retaining wall in high-filled embankment of mountainous expressway can not only save the height and sectional area of retaining wall but also enhance the anti-slide performance and stability of embankment. The working mechanism of CRS is not yet clear as which is a new and more complex retaining structure. The key issues we focused on is the stressing state and stability of the CRS when it used in engineering practice. In this thesis, the stressing state and stability the CRS suffering the design traffic load were analyzed by experimental investigation, numerical simulation and parametric study based on practical engineering. The main contents of this thesis are as follows:(1) The actual stress state of the CRS include the bending moment and axial force of the anti-slide pile and earth pressure of the retaining wall were studied based on the field measurements. The results show that the bending moment and axial force of the anti-slide pile increased first and then decreased as the depth of anti-slide pile increased, and the maximal value of bending moment and axial force occurred at the sliding surface. The earth pressure increased with the depth of the retaining wall and the maximal value(73 k Pa) existed at the bottom of the retaining wall.(2) A three-dimensional finite difference numerical model was built by using FLAC3 D and the model was checked according to the field test data. Meanwhile, the stress and stability of the CRS suffering the design traffic load was also analyzed. The results show that the anti-slide pile was mainly loaded by the horizontal load and the limit state of the CRS was determined by the shear capacity of anti-slide pile. The stability of the CRS under the design driving load can meet standard requirements.(3)The effect of some key factors, including the density and shear strength of fill, the spacing and shear strength of the anti-slide pile, and the thickness of the retaining wall, on the stress states and stability of CRS was further studied. The result shows that the density and shear strength of the fill had great effect on the stress state of anti-slide pile and the stability of the CRS while the pile spacing and anchorage depth of the anti-slide pile had little. The factors which effect on the earth pressure were the main factors of the stress and stability of the CRS.