Analyses Of Mechanical Behavior And Stability Of Reinforced Soil Retaining Wall On Deformable Foundation

The Reinforced Soil Retaining Wall (RSRW) has been widely used in civil engineerings such as bridge approach、 bulkhead wharf and retaining structure,the economic benefits, social benefits and environmental benefits are noticeable.Now,the research of RSRW focus mainly on the competent foundation all over the world,the relevant design theory and method has been mature and the relevant standard has been formed.However,there is little known about the mechanical behavior and stability of RSRW constructed on foundation where exists deep soft soil layer which will leads to large deformations during the construction process. This paper study the theory and practice based on these peradventure,the main works and conclusion are as follows:(1)Using FLAC 3D finite difference program to establish a three-dimensional numerical model to model a RSRW constructed on foundation where exists deep soft soil layer. The numerical calculation of foundation settlement, foundation deformation and tensile stress of reinforcement are in good agreement with the measured values, the reliability of the model is verified.(2)With the verified model, the mechanical characteristics of RSRW is analysed in the process of construction and working state.The results show that the wall deformation is the bulge shape, the maximum deformation occurs between the wall height 0.3-0.6H;The reinforcement caused the redistribution of earth pressure of RSRW，resulting in the transfer of earth pressure to the wall. Due to the flexible wall face, the earth pressure at the wall face decreases rapidly. Reinforcement tensile stress focuses on 2-7th layer near the wall face region. The reinforcement tensile stress decreases gradually up to the wall height and the position of maximum tensile stress on single reinforcement moves towards the end of reinforcement. Compared with 0.3H method shape,the potential rupture surface shape locates on the outside of 0.3H method shape below the wall height 4m and on the opposed side above the wall height 4m.(3)The differential settlement has obvious influence on mechanical behavior of RSRW. With the decrease of distortion level of the foundation(ratio of maximum differential settlement to the length away from the wall face), the wall face deformation gradually decreases and the position of maximum wall face deformation gradually increases from 0.2H to 0.4H.When the distortion level lower than 3.7%,the wall face deformation and its position no longer changes and the deformation just happens to the wall height higher than 0.6H, showing the trend of rotational failure; With the distortion level increases,the reinforcement stress at the lower part of the RSRW increases,the reinforcement stress at the upper part of the RSRW exhibits double peak phenomenon, showing a larger stress at the end of the reinforcement,the potential repture surface moves towards the wall face.(4)There is a significantly wall face deformation when the depth of soft soil layer is shallow.With the increase of the depth of the soft soil layer,the wall deformation decreases,the lateral earth pressure at the back of the wall face increases but still lowering the active earth pressure.The reinforcement stress is always high along the reinforcement at the bottom of the RSRW, exhibiting a double peak state.Along with the increase of the depth of the soil,the stress at the end of the reinforcement decreases and increased near the wall face.(5)The position of soft soil layer has great influence on the overall stability of RSRW.When the depth of soft soil layer is shallow,the wall destroyed with a deep sliding surface. And the failure mode changed from the deep sliding failure to overturning with the increase of the soft soil layer depth and the safety factor increases,the potential repture moves away from the wall face.