Research On Cohesionless Soil Waterfront Retaining Wall Stability Based On Upper-bound Analysis

The retaining wall in the waterfront area is collectively called “waterfront retaining wall”,which protects the safety of roadbeds,coasts,and wharves along the river.Due to the complexity of geological conditions,the assessment stability of the waterfront retaining wall becomes a difficult problem.In addition,the seismic stability of waterfront retaining walls in seismically active coastal areas has always been a hotspot.Although numerous researches on the waterfront retaining wall stability have been done.However,most scholars were mainly based on limit equilibrium theory,that was,the specific parameter expression can be derived by the force balance or moment balance equation after the earth pressure and its location were solved.Due to complex geological conditions,the earth pressure calculation is usually very complicated,and cannot involve the stress-strain relationship and plastic flow of the soil.Moreover,its exact location still is a topic of much debate.With the application of the upper bound method of limit analysis in the geotechnical field,the dry-backfill retaining wall stability,which established the kinematically admissible wall-soil system to avoid the determination of earth pressure and its location,was investigated.Although this method has been widely applied to the stability problem of the dry-backfill retaining wall.However,theoretical research with respect to the waterfront retaining wall with partially submerged soil is still lacking.Therefore,based on the upper bound method theory and the linear sliding surface assumption,the stability of cohesionless soil waterfront retaining wall with different displacement modes has been evaluated considering the conditions of earthquake load and without earthquake load.The main studies are listed as follows:(1)The safety coefficient of anti-sliding without seismic and the earthquake yield acceleration coefficient under seismic conditions,respectively,have been deduced by establishing the wall-soil system and velocity field of wall translational movement and the whole soil wedge sliding based on the upper bound theory.(2)The soil wedge is divided into numerous rigid strips parallel to the straight sliding surface by the inclined strip method.Combining the upper bound theorem and multiblock slide theory,the safety coefficient of anti-sliding without seismic and the earthquake yield acceleration coefficient under seismic conditions,respectively,have been deduced by establishing the wall-soil system and velocity field of wall rotation and the whole soil wedge multi-block slide.(3)The numerical calculation of the theoretical formula was realized by MATLAB,and the impact of water level along both sides of the wall,internal friction angle,and wall-soil friction angle on the waterfront retaining wall stability and backfill ultimate fracture angle has been discussed.The anti-sliding/overturning stability factors of the waterfront retaining wall were verified by the element simulation results.In comparison with the limit equilibrium method proposed by predecessors,the rationality of the seismic yield acceleration coefficients of the waterfront retaining wall with different displacement modes were verified.