Plastic Design Theory of Frozen Wall Thickness in an Ultradeep Soil Layer Considering Large Deformation Characteristics

Abstract

Frozen wall design theory is a key technique of the freezing method. However, previous design theories for a deep artificial frozen wall have neglected the influence of shaft flank displacement, that is, the displacement of the inner boundary of a frozen wall. Thus, the associated designs tend to be unsafe and earthwork excavations tend to be underestimated. This study builds a new design theory for frozen wall thickness which considers the influence of a large strain and obtains new solution formulas for the thickness and excavation radius before deformation occurs. The analytical results are compared with numerical calculation results by analyzing the influences of various parameters, such as crustal stress, cohesion and internal friction angle of frozen soil, and cohesion and internal friction angle of unfrozen soil as well as the elastic modulus of the ground, on the frozen wall thickness and the shaft flank displacement. The results indicate that the new formula is applicable for large deformation calculation with a strain of up to 0.2. The new formula can accurately calculate the amount of excavation earthwork and serves as a safer and more reasonable theoretical support for the design of frozen walls in ultradeep soil layers.