The thermal response of the ground can be a major concern for many engineering and earth science problems. Some typical problems include the degradation of permafrost due to construction or climate change, artificial ground freezing during construction activities, and the effect of convective heat transfer on earth embankments or soil cover performance. Many of these problems involve interaction with the hydrogeological system and climate.
GeoStudio can consider heat transfer with phase change due to conduction and convection with moving water and/or moving air. Boundary condition options enable steady state or transient analyses. A “convective surface” boundary condition is implemented for artificial ground freezing where a flowing fluid in a closed piping system removes heat from the ground. The land-climate interaction boundary condition can be used to model the effect of net radiation, air temperature, wind speed and snow depth on the ground temperature response. Add-In constitutive models can be developed in SIGMA/W and SLOPE/W to use results from a TEMP/W analysis to assess deformations or changes in stability based on temperature-dependent ground strengths.
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TEMP/W is used to model the freezing front propagation around a pipeline. The examples demonstrates the use of circular regions and the application of the appropriate boundary conditions and material properties.
Artificial ground freezing is used in many engineering projects to excavate and construct mine shafts, tunnels or other underground structures through water bearing, often unstable, ground formations. This example demonstrates a procedure for modeling the freeze wall growth for a mine shaft project.
Groundwater flow can have a significant effect on ground freezing because heat flow via convection is often more effective at moving heat than conduction alone. Numerical analysis of the conduction- convection process requires a coupling of the heat and water transfer equations. This example discusses the methodology and material properties required for conducting a heat transfer analysis involving groundwater flowing around a freeze pipe.
These two examples (a transient analysis of thermosyphons installed near Fairbanks, Alaska, and two years of transient analysis of a single thermosyphon) use TEMP/W to determine whether a permafrost zone can be maintained beneath a heated building.
SEEP/W analyzes groundwater flow within porous materials such as soil and rock. Its formulation enables analyses ranging from simple saturated steady-state problems to sophisticated saturated/unsaturated time-dependent problems.
SIGMA/W performs stress and deformation analyses of geotechnical, civil and mining works. It can perform a simple linear elastic deformation analysis or a highly sophisticated soil-structure interaction analysis with non-linear material models and coupling to seepage analysis.
TEMP/W enables analysis of thermal changes in the ground due to environmental factors or the construction of facilities such as buildings or pipelines. TEMP/W can be applied to the geothermal analysis and design of geotechnical, civil, and mining engineering projects.
VADOSE/W analyzes interactions at the ground surface to determine environmental impacts on the movement of water through the unsaturated vadose zone and into the local groundwater regime. Potential interactions considered in VADOSE/W include infiltration due to rainfall and snowmelt, root transpiration, gas diffusion, and surface runoff, evaporation and ponding.