Rock mechanics is one of engineering branch that applies the principles of mechanics in studying the behaviors and characteristics of geological materials (rock, discontinuities, and related structures) and the reaction of these materials towards loading or forces. This subject is pretty much interesting besides soil related subjects that often or normally being thought to the future engineers.
Two main reasons of why this engineering knowledge is also essential:
Rock formation at site.
- Rock is one of most important construction materials such as aggregate for cement, gabion, road surfacing (sub-base and road-base), coastal embankment and etc.
- It acts as a major components for engineering structures such as slopes, foundation of structure, and tunnels.
Stability of the rock is very important especially for slopes and tunnels. The excavated slopes and tunnels stability in rock is greatly depends on three factors:
- The strength and characteristic of rock,
- The structural weakness (weak-plane) and discontinuities in rock,
- Weathering degree (slow or rapid) that affects the rock physically.
The Important Scopes
Cross sectional of rock for engineering studies.
- Understanding of rock properties and characteristics that is important for civil construction works,
- Measuring the behavior and characteristics of mass and materials properties of rock using laboratory and field testing methods,
- Application of measured into design, with due to consideration on differences between mass and material properties,
- Essential stabilization methods used upon rock engineering structures and the consideration on changes of design,
- Measuring and monitoring upon the changes of rock properties using instrumentation during construction works,
- Basic construction and excavation methods of rock engineering structures.
The Testing
Specific testing methods can be used to evaluate and to determine the strength and characteristics of rocks numerically (in addition to the subjective description provided by geologist). The technical standards of test methods and procedures for laboratory and field normally as accordance to International Society of Rock Mechanics (ISRM – Ref. 5), and other standards like ASTM, BS, and S. African SRM.
The two category of rock testing; Laboratory rock testing, and In-situ rock testing.
Rock Specimen being tested to failure.
Laboratory Rock Testing
The testing of rock conducted for measuring and evaluating the changes of rock properties as well as its properties by applied loading or force. The properties will include physical, index and strength whereby the behavior include deformation and failure mode.
In general, laboratory testing could be divided into two types:
- Index test and Indirect Strength test,
- Direct test or Strength test.
In-situ Rock Testing
The testing approach is to access the rock properties at the site scene where it is found. It will include large-scale of direct strength test on site as the preparation and the equipment could be expensive, complex, and time-consuming.
Among the common field tests of rock:
- Plate-bearing test,
- Direct Shear test.
In conclusion, this knowledge is essential for excavation of tunnels, stability of slopes, and foundation of structures.
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Author: Civil-Guy | Blog: Civil Craft Structures | Subscribe: RSS or Email
