Numerical Analysis Of Reinforced Earth Retaining Wall Under The Ground Motion Load Condition

The field investigations for the subgrade disasters in Wen Chuan Earthquake showed that the destruction of gravity retaining wall was the main constitute factor which caused the subgrade disasters,and the reinforced soil retaining wall in the earthquake showed good seismic performance.Although the reinforced soil retaining wall have been widely used in engineering,the study of its mechanics theory lagged relatively,and the dynamics theory was studied on the basis of the theory of statics assumption,that was the pseudo-static method.Too many assumptions in the pseudo-static method often lead to the limitations for using,and couldn't analyze the dynamic response laws of the reinforced soil retaining wall during the time history of seismic acceleration.In order to understand the seismic performance of reinforced soil retaining wall more clearly,the numerical analysis method for the seismic dynamic simulation was introduced,the international geotechnical numerical analysis software which named FLAC3 Dwas used to study the seismic dynamic characteristics,the Elcentro seismic waves with tangential model was chosen to apply to the bottom stimulatory.To study the influence of the sensitive parameters on the seismic response characteristics of the retaining wall,18 kinds of working condition model were built for calculation and analyses.The main research contents and achievements were as follows:(1)The development process of reinforced soil retaining wall technology,the theory of practice achievements and research methods both at home and abroad were introduced,the composition and design methods of reinforced soil retaining wall were summarized both at home and abroad.(2)The basic working principle and failure mode,the internal stability and external stability analyses of the reinforced soil were discussed,the seismic active earth pressure calculation method of each industry norms was summed up.The seismic dynamical soil pressure calculation formula was corrected on the basis of the coulomb theory,namely Correction Method.(3)FLAC3D numerical model was constructed,the results showed that a variety of isoclines of cloud maps of subgrade soil basically acted like the horizontal layer distribution,and at the boundaries of ribbon reinforced and unreinforced,the isoclines obviously turned,showed that the movement trends of different materials in the process of rock mass in the earthquake were presented differently.The acceleration increasedgradually from bottom to top and on the top of surface had a maximum.The speed increased gradually from bottom to top and got fastest in the middle of the road.The potential fracture plane of reinforced soil retaining wall started in the corner of foundation,and extended upward in a fixed slope until a certain height then developed vertically,shaped similarly to logarithmic spiral surface.(4)Compared with the results of the numerical analyses in 18 kinds of working condition and discussed the influence of the foundation sensitive parameters and the seismic peak acceleration on the dynamic response rules of the retaining wall.The results showed that the seismic performance of reinforced soil retaining wall on the foundation of rock was better than the foundation of clay.The seismic peak acceleration and the height of wall were proportional to the acceleration amplification system.In addition,in the same sensitive parameter condition,the seismic performance of the reinforced soil retaining wall was better than gravity retaining wall.