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CRS Consolidation Cell

Marine Geotechnical Laboratory  /  CRS Consolidation Cell  /  TruePath Triaxial Cell

The CRS test system that allows tests to be performed at a variety of strain rates ( less than 1% per hour to a few percent per hour) as required by the permeability and stiffness of the sediment sample. Each experiment consists of four phases:

1. sample selection, trimming, and preparation
2. sample back pressure saturation
3. consolidation of sample
4. unloading and breakdown of experiment.

Phase 1 involves removing the sample from the core liner and carefully trimming it to fit in the fixed-ring consolidation cell (2.5cm height by 6.34cm diameter). In Phase 2, the sample backpressure is increased while maintaining a constant sample height and then the sample is held at constant pressure and constant height to ensure total water saturation. Phase 3 is the consolidation, and unload/reload cycles of the experiment, while back pressure is held constant, sample diameter is constant, vertical strain is controlled, and sample pore pressure and total vertical stress are measured. The 4th Phase is the breakdown of the experiment including drying the specimen and evaluating the volume of dry solids required for reduction of the experimental data.

Figure 1. CRS consolidation cell in load frame (center) connected to pore pressure pump (right) and computer (left) that controls the experiments while recording experimental data. Click for larger image.

Figure 2. Typical void ratio versus effective vertical stress (log scale) plot that is generated from a CRS experiment. These results are from a specimen taken at 6.8 meters below the seafloor from R/V Marion Dufresne giant piston core 2567.