Study on environmental impact of artificial horizontal freezing method in subway connecting passage

When the subway is built in complex urban strata, especially when excavating near buildings, it is necessary to strictly control the freezing amount by adopting artificial freezing method. At present, the theoretical calculation is aimed at the frozen rise under ideal conditions, but for complex geological conditions, the simplified model results are difficult to meet the actual requirements. However, numerical calculation can adapt to complex strata and complex boundary conditions. Therefore, in this paper, the environmental impact of artificial horizontal freezing method in subway connecting passage is studied by numerical simulation, and the change of thermophysical parameters with the change of temperature field is considered in the simulation. The simulation method in this paper provides guidance for actual construction.

Investigation of Frost-Heaving Characteristics of Horizontal- Cup-Shape Frozen Ground Surface for Reinforced End Soil Mass in Shield Tunnel Construction

Artificial freezing method is commonly adopted for reinforcingend soil mass of shield tunnel in the weak and rich aqueousformation, which is expected to prevent the construction riskin the originating and arriving of shield machine, whereas thearrangement of freezing pipes is sometimes varied due to variouscomplex limitations, and the corresponding frost-heavingcharacteristics of ground surface also differs from others. Inthis paper, a case of artificial freezing end soil mass with cupshape arrangement of horizontal freezing pipes is studied byfield investigation and numerical analysis, in which a numericalmodel coupled with water-heat-force interactions is proposedfor appropriately evaluating the frost-heaving characteristicsof ground surface in artificial freezing method. Theresults demonstrate that all the considered factors on brinetemperature, buried depth and cup bottom thickness have significantlyinfluences of frost-heaving characteristics of groundsurface in the artificial ground freezing (AGF) with cup shapearrangement of horizontal freezing pipes, in which the frostheave displacement of horizontal-cup-shape frozen groundsurface is increased with the increasing brine temperature andburied depth, whereas that is decreased with the increasing cupbottom thickness.

Study on the Frost Heave Characteristics of Artificial Frozen Soil Under Different Freezing Mode

At the self-developed DZL-001 computer control of frozen soil frozen-heave test machine, use artificial freezing method carry out vertical and lateral freezing two modes frost heave test of remoulded clay, each mode test includes under no replenishment and replenishment conditions. Monitor the temperature, moisture and frost heave of frozen soil at different location. Compare the similarities and differences of frost heave characteristics of two modes, master the frost heave characteristics of artificial frozen soil. The results provide a certain guidance and reference meaning to layer sidewall structural design.