Mechanical properties of film-bag sand cofferdam: theoretical analysis and numerical study

To study the mechanical properties of the membrane bag sand cofferdam under the action of geotextile hoop during the construction, the theoretical derivation of the film-bag sand enhancement mechanism was carried out firstly. A finite element model of sand blowing cofferdam with measured material parameters was established based on the ANSYS platform, and then different pipes were used to calculate the bag height under self-weight and external load, and the variation law of self-weight and external load, as well as the sand blowing cofferdam under different concrete slab thickness was analyzed. The main conclusions include: (1) The relationship between the height of the membrane sandbag and the tensile force of the soil sandbag is proposed, the relationship between the shape of the sandbag and the external load is further deduced. (2) The axial tension of the type bag is proportional to the quadratic of the height of the type bag sand without considering the friction condition. (3) As the concrete slab thickness increases, the vertical settlement of the blown sand cofferdam gradually decreases under the action of the cast-in-place bracket, and the reduction of the uneven settlement in the cross-bridge direction is greater than that of the vertical settlement.