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Gulf Coast Repository

Torvane (TOR)

Overview

Thumbnail image of Torvane Shear strength in sediments is the maximum resistance of a material to deformation by shear stress and can be measured by a torvane. Shear strength is a way to measure slope stability as it relates to friction, particle interlocking, and cohesion. The torvane is suitable for sediment not affected by cementation (e.g., saturated, clay-rich, soft sediment).

Instrument Make and Model

ELE International 26-2261

Estimated Measurement Time

  • Sample Preparation: none–5 minutes
  • Sample Measurement: 1 min/measurement

Principles & Analytical Capabilities

Sediment strength is generally measured on section halves using the Torvane (TOR) handheld instrument. Shear strength measurements should be considered only approximate, particularly because the influence of pore pressure changes during the undrained experiment cannot be estimated.

Three sizes of vanes are supplied:

  • The standard vane (25.4 mm diameter), has a stress from 0 to 1 kg/cm2, this is also the approximate range of torque that can be easily applied by finger pressure. It is used for fully saturated cohesive soils with undrained strength independent of normal pressure. The stress range permits it to be used for clays varying in consistency from very soft to stiff.
  • The sensitive vane (47.5 mm diameter), is provided for use with remolded samples. It is for a range of 0 to 0.2 kg/cm2. It has a ratio of 0.2.
  • The high-capacity vane (19 mm diameter) is used with stiffer clays. It is for a range of 0 to 2.5 kg/cm2. It has a ratio of 2.5.

Data Generated

Data components:

  • Torvane shear strength (N/m2): strength value at the failure point of the sample, determined by maximum torque (N.m) divided by the adapter foot constant (m3).
  • Penetration direction: orientation of penetration (orthogonal to the shear experiment plane). Values include "into X", "into Y", "into Z", or "into -Z".
  • Adapter foot identifier: which adapter was used on the Torvane: "regular", "large", or "small".

Data files:

  • Results (CSV): manually recorded data by user

Data Example

Graph of oxygen and hydrogen indexes in relation to the three kerogen types from Hole U1545A of IODP Expedition 385 in the Guaymas Basin.
Shear strength measurements from Hole U1459B of IODP Expedition 356 in the Perth Basin.1

Procedures & Manuals

References

1  Gallagher, S. J., Fulthorpe, C. S., Bogus, K. A., Auer, G., Baranwal, S., Castañeda, I. S., Christensen, B. A., De Vleeschouwer, D., Franco, D. R., Groeneveld, J., Gurnis, M. C., Haller, C., He, Y., Henderiks, J., Himmler, T., Ishiwa, T., Iwatani, H., Jatiningrum, R. S., Kominz, M. A., … Zhang, W. (2017). IODP Expedition 356 Vane shear strength (Torvane) [Data set]. International Ocean Discovery Program. https://doi.org/10.5281/zenodo.13948219