Rock mechanics is a theoretical and applied science of the mechanical behavior of rocks and rock masses. Compared to geology, it is the branch of

mechanics Mechanics () is the area of physics concerned with the relationships between force, matter, and motion among Physical object, physical objects. Forces applied to objects may result in Displacement (vector), displacements, which are changes of ...

concerned with the response of rock and rock masses to the force fields of their physical environment. GrusSand

Borehole miming tool and technology principle schematic

Background

Rock mechanics is part of a much broader subject of

geomechanics Geomechanics (from the Greek ''γεός'', i.e. prefix ''geo-'' meaning "earth"; and "mechanics") is the study of the mechanical state of the Earth's crust and the processes occurring in it under the influence of natural physical factors. It involv ...

, which is concerned with the mechanical responses of all geological materials, including soils. Rock mechanics is concerned with the application of the principles of engineering mechanics to the design of structures built in or on rock. The structure could include many objects such as a drilling well, a mine shaft, a tunnel, a reservoir dam, a repository component, or a building. Rock mechanics is used in many engineering disciplines, but is primarily used in Mining, Civil, Geotechnical, Transportation, and Petroleum Engineering. Rock mechanics answers questions such as, "is reinforcement necessary for a rock, or will it be able to handle whatever load it is faced with?" It also includes the design of reinforcement systems, such as rock bolting patterns.

Assessing the Project Site

Before any work begins, the construction site must be investigated properly to inform of the geological conditions of the site. Field observations, deep drilling, and geophysical surveys, can all give necessary information to develop a safe construction plan and create a site geological model. The level of investigation conducted at this site depends on factors such as budget, time frame, and expected geological conditions. The first step of the investigation is the collection of maps and aerial photos to analyze. This can provide information about potential sinkholes, landslides, erosion, etc. Maps can provide information on the rock type of the site, geological structure, and boundaries between bedrock units.

Boreholes

Creating a

borehole A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water ( drilled water well and tube well), other liquids (such as petr ...

is a technique that consists of drilling through the ground in various areas at various depths, to get a better understanding of the sites geology. Boreholes must be spaced properly from one another and drilled deep enough to provide accurate information for the geological model. Samples from the borehole are investigated and factors such as rock type, degree of weathering, and types of discontinuities are all recorded.

Methods

Testing the properties of a rock is essential to understand how stable or unstable it is. Rock mechanics involves 3 categories of testing methods: tests on intact rocks, discontinuities and rock masses. Two direct methods of testing that can be done are laboratory tests and in-situ tests. There are also indirect methods of testing which involve correlations and estimations that are obtained by analyzing field observations. The data these testing methods provide are crucial for the design, structure and research of rock mechanics and rock engineering. Intact rocks and discontinuities can be tested in the laboratory through running small-scale experiments to gather empirical data, however rock masses require some larger-scale field measurements rather than laboratory work due to their more complex nature. Laboratory tests provide both classification and characterization of the rock as well as a determination of what rock properties will be used in the engineering design. Examples of some of these laboratory tests include: sound velocity tests, hardness tests, creep tests and

tensile strength Ultimate tensile strength (also called UTS, tensile strength, TS, ultimate strength or F_\text in notation) is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials, the ultimate ...

tests. In-situ tests, which is when the rock being studied is subjected to a heavy load and then being watched to see if it deforms, provides an insight into what impacts a rock masses' strength and stability. Understanding the strength of a rock mass is difficult but necessary for ensuring the safety of anything built on or around it, and it all depends on different factors the rock mass faces, such as the environmental conditions, size of the mass, and how discontinued it might be.

References

* * Coates, D F. (1981) "Rock Mechanics Principles." Canada: Monograph 874. {{Authority control Petrology Soil mechanics Mining engineering

Background

Assessing the Project Site

Boreholes

Methods

See also

References