Viscoelastic analysis of interaction between freezing wall and outer shaft wall in freeze sinking

摘要

In order to reasonably determine the external load of outer freezing shaft wall, it is necessary to conduct interaction study between frozen soil wall and outer shaft wall. First, based on the characteristic of three-stage compressive deformation of foam board, a relational expression of such radial deformations as frozen soil wall, outer shaft wall, and foam board is established; then based on the homogeneous viscoelastic model of frozen soil wall, with the rigidity in different compression stages of foam board being regarded as a constant, an expression of deformation pressure is derived. According to the research conducted in combination with project examples, the foam board remarkably slowed down the increase in deformation pressure; for steady creep frozen soil wall, the final value of deformation pressure should be effectively reduced; for unsteady creep frozen soil wall, the final value of deformation pressure has nothing to do with the effect of foam board, and tends to be equal to the level external load of frozen soil wall. The research shows that as the depth of alluvium rises, the frozen soil wall under high pressure is to gradually present a unsteady creep characteristic and that the value of level external load of outer shaft wall in extra-thick alluvium can be regarded as equal to permanent level ground pressure.