Study On The Influence Of Bagged Sand Cofferdam Width And Sandbag Strength On The Deformation And Failure Of Foundation

Bagged sand cofferdam is a kind of embankment widely used in soft soil areas,with features such as simple construction and low construction cost.The industry has accumulated a wealth of experience in the construction of bagged sand cofferdam.However,occasional cases of collapse and instability have occurred in practical projects.Therefore,it is of great theoretical and practical significance to carry out an in-depth study on the failure mechanism of bagged sand cofferdam.In this paper,a series of model tests and finite element numerical simulations are carried out,and the influence of the width of embankment and the strength of sandbags on the deformation and damage characteristics of soft soil foundations on bagged sand cofferdam has been studied.The main research contents and results are summarized as follows:(1)The deformation and failure characteristics of soft soil foundation under flexible foundation and rigid foundation are compared and analyzed through model tests and numerical simulations.The pressure distribution of rectangular flexible foundation and rigid foundation base is large in the edge and small in the middle,while the distribution of trapezoidal flexible foundation is large in the middle and small in edge.The trapezoidal flexible foundation under the action of the ground soil to the sliding failure of both sides,and the rigid foundation is different,the base did not appear obvious wedge-shaped elastic zone.(2)The effect of the width of the bagged sand cofferdam on the deformation of the foundation,the distribution of the axial force of the geotextile,and the failure mode was analyzed by numerical simulation.The damage of the cofferdam foundation shows two forms with the change of the width of the cofferdam.There is a critical width between the two forms.The critical width of this simulation condition is about 28 m.When the width of the cofferdam is smaller than the critical width,the overall failure of the foundation occurs.If the width of the cofferdam exceeds the critical width,the sliding of the slope will occur.(3)The effect of sandbag geotextile strength on the deformation and damage of the cofferdam foundation was studied by using model tests and numerical simulations.Combined with model tests and numerical results,it was found that increasing the strength of sandbag geotextiles can reduce the settlement and lateral deformation of shallow foundations,reduce the shear stress level of soft soil foundation.And delay the development of the plastic zone of the foundation,in order to enhance the stability of soft soil foundation.(4)The numerical simulation results show that the strength of the geotextiles in each layer played different strength when the cofferdam failure.In the calculation of the stability,using different strength according to the strength exerted in each layer geotextile can reflect the real situation of the cofferdam unstability more accurate.Combined with reclamation project in Nangang industrial Zone,Tianjin,had preliminary validated that method.