The cement-soil wall（SMW construction method）as a retention technique enjoys many advantages in soft soil areas

but at present

the wall-soil interaction mechanism of SMW construction method is not well understood

which restricts its popularization and application.To further explore the wall-soil interaction mechanism

a large-scale test model was built according to the SMW construction method in soft soil areas

and various tests were conducted under different displacements of the top wall

lateral earth pressures of the side wall and section steel strains.The experimental results indicated that there was a U-shaped curve between the displacement rate and the foundation depth

while there was a S-shaped curve for the displacement;the displacement exhibited remarkable time effects and an optimal embedment ratio was obtained for the retaining wall.It was also observed that there was a parabolic distribution of the measured active earth pressure at the back of the wall;both the displacement and displacement rate of the foundation pit wall would affect the development of the ultimate earth pressure;the measured limit active earth pressure ranged between the Rankine active earth pressure and the earth pressure at rest

while the measured limit passive earth pressure was far smaller than the theoretical value.Compared with section steel retaining walls

the composite retaining walls of cement-soil and section steel had better bearing capacity

rigidity and deformation compatibility.It was therefore suggested that the contribution made by cement-soil to the rigidity of composite retaining wall shall deserve consideration when designing supporting structures using the SMW construction method.