| The retaining wall is widely used in the field of civil engineering.The use of expanded polystyrene（EPS）geotechnical geofoam cushion behind the retaining wall can reduce the earth pressure acting on the wall,but there are few studies on the design method of the EPS cushion behind the retaining wall.In this thesis,based on the laborotary model tests and numerical simulation,the mechanical characteristics of the rigid retaining wall with EPS cushion behind the wall are studied.Furthermore,the design method of EPS cushion behind the rigid retaining wall is proposed.The main contents and results are as follows.（1）The model tests of the retaining wall with/without EPS cushion to verify the decompression performance of EPS cushion are conducted.The influence of the elastic modulus and thickness of EPS cushion on the earth pressure of retaining wall are analyzed.The results show that the decompression efficiency of EPS cushion increases with the decrease of its elastic modulus or increase of its thickness.（2）The numerical model of rigid retaining wall is established by FLAC3D.Based on this numerical model,the displacement required for the backfill to reach the active state（active displacement）and active earth pressure of retaining wall are studied.The compression of the cushion and the earth pressure of the retaining wall under different conditions of the EPS cushion are studied,and compared with the active displacement and active earth pressure.The results show that the earth pressure of retaining wall decreases continuously,but the trend slows down gradually when the cushion compression is less than the active displacement.However,when the compression of cushion exceeds the active displacement,the earth pressure of retaining wall will no longer decrease significantly.（3）The effects of the gravity of the filling,the friction angle of the filling,the interface friction angle of EPS-filling,and overloading on the filling are analyzed in detail.The results show that the gravity of the filling and the interface friction angle of EPS-filling have little influence on the decompression efficiency of EPS cushion,while the decompression efficiency decreases with the decrease of the filling’s friction angle,and the overloading only has a great influence on the decompression efficiency of EPS cushion at the upper part of the retaining wall.（4）Taking the decompression effect,pavement settlement and construction difficulty of EPS cushion into consideration comprehensively,a new design method of EPS cushion with the decreasing of elastic modulus and thickness of EPS cushion from the bottom to the top of the retaining wall is proposed. |
