The Vindhyan supergroup rocks are exposed over a very large area in the central India and is believed to be broadly undeformed and unmetamorphosed. It constitutes one of the thickest sedimentary deposits in the world. The rock types are generally alternate succession of sandstone, shale and occasional occurrence of carbonates. The characteristic feature of these sedimentary rocks is that they are horizontal to sub-horizontal bedded rocks with variable thickness. In such bedded successions, influence of weathering plays very important role in rock mass strength degradation and slope modifications. It is due to this reason that the design life of slopes is affected and many slope failures are seen resulting in failure of structures too. The present study aims to investigate a cut slope section in Sohagi district, Rewa, M.P. where alternate shale, sandstone successions are exposed leading to a number of slope failures. The evaluation of rock/soil geotechnical properties becomes very important for design of engineering projects. The rock/soil samples collected from the field were tested for their chemical analysis, strength and Atterberg limits. The results reveal that the layers rich in clay such as kaolinite, glauconite are very prone to weathering and suffers significant rock mass strength degradation. The structural integrity is completely lost, and the load bearing capacity is diminished. The underlying/overlying layers react to this weathering attributes by development of overhanging blocks, the shape and size of which are restricted by vertical joints and layer thickness. This type of differential weathering phenomenon modifies the engineering properties of the exposed rock mass and significantly transforms the slope material and failure mechanisms.

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Analysis of Engineering Properties of Weathered Sedimentary Rocks

  • Digvijay Singh,
  • Supriya Singh,
  • N. K. Rai,
  • P. K. Singh

摘要

The Vindhyan supergroup rocks are exposed over a very large area in the central India and is believed to be broadly undeformed and unmetamorphosed. It constitutes one of the thickest sedimentary deposits in the world. The rock types are generally alternate succession of sandstone, shale and occasional occurrence of carbonates. The characteristic feature of these sedimentary rocks is that they are horizontal to sub-horizontal bedded rocks with variable thickness. In such bedded successions, influence of weathering plays very important role in rock mass strength degradation and slope modifications. It is due to this reason that the design life of slopes is affected and many slope failures are seen resulting in failure of structures too. The present study aims to investigate a cut slope section in Sohagi district, Rewa, M.P. where alternate shale, sandstone successions are exposed leading to a number of slope failures. The evaluation of rock/soil geotechnical properties becomes very important for design of engineering projects. The rock/soil samples collected from the field were tested for their chemical analysis, strength and Atterberg limits. The results reveal that the layers rich in clay such as kaolinite, glauconite are very prone to weathering and suffers significant rock mass strength degradation. The structural integrity is completely lost, and the load bearing capacity is diminished. The underlying/overlying layers react to this weathering attributes by development of overhanging blocks, the shape and size of which are restricted by vertical joints and layer thickness. This type of differential weathering phenomenon modifies the engineering properties of the exposed rock mass and significantly transforms the slope material and failure mechanisms.