What are the properties of rock mass?

Parameters for Rock Mass Classification

  • Strength and deformability of intact rock.
  • Rock Quality Designation (RQD) which considers the intensity of fracturing in a drill core.
  • Rock fractures parameters (spacing, orientation, width, roughness, weathering, etc.)
  • Groundwater pressure and flow.
  • In-situ stress.

What is rock mass rating used for?

RMR combines the most significant geologic parameters of influence and represents them with one overall comprehensive index of rock mass quality, which is used for the design and construction of excavations in rock, such as tunnels, mines, slopes, and foundations.

What are the parameters of RMR system?

The following six parameters are determined for each structural unit: Uniaxial compressive strength (UCS) of intact rock material, rock quality designation (RQD), joint or discontinuity spacing, joint condition, groundwater condition, and joint orientation.

What does rock mass describe?

A rock mass is an inhomogeneous material built up of smaller and larger blocks/pieces composed of rock material. A great variety exists, both in the composition of the rock material and in the struc- ture and occurrence of its discontinuities.

What are the ways to classify rock mass?

Design methods In engineering in rock, three design strategies can be distinguished: analytical, empirical, and numerical. Empirical, i.e. rock mass classification, methods are extensively used for feasibility and pre-design studies, and often also for the final design.

What are the engineering properties of rocks?

Common engineering properties typically obtained from laboratory tests include specific gravity, point load strength, compressive strength, tensile strength, shear strength, modulus, and durability. Rock mass properties are determined by visual examination and description of discontinuities within the rock mass.

What is rock mass strength?

The rock. mass strength criterion is based on a. Mohr-Coulomb model for shear strength in which. the cohesion and friction are those of the rock mass. and determined by classification of the rock mass.

What is RMR and Q system?

Although the rating methods of RMR and Q-system are additive and multiplicative, respectively, the basic concepts of both schemes are similar. Both schemes allocate the ratings to the properties that influence the rock mass behavior and then quantitative figures such as total-RMR and Q-value are produced.

What are the three most common rock mass classifications?

This system forms the foundation for the development of three most common rock mass classification schemes i.e. Q, RMR, and GSI. This conservative method has been modified and improved over time and is still used today to aid in the design of tunnels.

On which factors do the properties of rocks depend?

Answer: The principal factors controlling the strength of solid rocks are: I) mineral composition, structure and texture; 2) bedding, jointing and anisotropy; 3) water content; 4) state of stress in the rock mass.