This invention named DetFroSS is designed to determine the shear strength of a frozen soil sample. DetFroSS comprises a chiller unit connected to a pair of chiller plates with corrugation through thermally insulated tubes. A thermally insulated loading cap is attached to the chiller plates. The apparatus also includes a direct shear box, which further comprises an upper half and a bottom half. Additionally, a mechanized system is configured to provide shearing loads and to measure vertical and horizontal deformations of the frozen soil sample. This setup allows for precise control and measurement of the mechanical properties of frozen soils under varying conditions, making it an invaluable tool for infrastructure development in cold regions.
Figure 1: A schematic of DetFroSS which is a test setup for determining frozen soil shear strength
In permafrost regions, accurately determining the mechanical behavior of frozen soils is crucial for the design and construction of various infrastructure projects such as foundations, railway tracks, mining operations, and tunneling. The challenge lies in measuring the shear strength and volumetric deformation of fully- or partially-saturated frozen soils, which are influenced by varying normal stresses and rates of shearing. Existing methods often lack the precision needed to account for these variables, leading to potential structural failures and inefficiencies.
- Precise Temperature Control: A chiller unit using ethylene glycol coolant, along with thermally insulated components, ensures accurate and stable temperature regulation during testing.
- Uniform Stress Application: The system applies stress uniformly across the soil sample, enhancing the reliability and consistency of shear strength measurements.
- Accurate Deformation Measurement: Integration of a Linear Variable Differential Transformer (LVDT) allows for precise measurement of both vertical and horizontal deformations of the soil specimen.
- Real-Time Temperature Monitoring: Thermocouples embedded in the setup provide continuous, real-time monitoring of temperature variations throughout the sample, ensuring detailed thermal profiling.
- Versatile testing capabilities: The direct shear box, with its upper and lower halves, facilitates versatile testing of both fully- and partially-saturated frozen soil samples under different normal stresses.
The device comprises a refrigeration-based test apparatus designed to determine the shear strength of frozen soil samples. At its core is a chiller unit (CU) that circulates pre-cooled ethylene glycol (EG) via thermally insulated tubes into a loading cap and a direct shear box (DSB), ensuring uniform and stable freezing. The DSB houses the soil specimen between two corrugated aluminium chiller plates that act as isothermal boundaries and provide mechanical grip.
A mechanized system applies vertical and horizontal loads to the sample and records deformation using Linear Variable Differential Transformers (LVDTs). A steel ball ensures uniform vertical stress application, while a load shaft measures shear resistance. Thermocouples placed along the specimen height enable precise thermal monitoring. The setup allows testing at varying temperatures (0 °C to –25 °C), under fully or partially saturated conditions, to evaluate soil shear strength and volumetric deformation.
The test-setup is working well and available for licensing
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By providing accurate measurements of frozen soil properties, it ensures safer and more reliable designs for foundations, railway tracks, tunnels, and other structures. This reduces the risk of structural failures and enhances the longevity and stability of constructions in permafrost areas.
- Permafrost soil testing.
- Railway track construction in cold regions.
- Mining and tunneling in permafrost areas.
- Stabilization of slopes using artificial ground freezing.
- Offshore structure construction.
Geography of IP
Type of IP
202021028356
526044