the site is having single lithological unit on banks as well as along river bed. river valley is approximately 20 m deep. as per stratighraphy of site upper unit which is ~200m thick overlies the older litho units. will such arrangement affect rock mass strength of top unit which is under studies?
Dear Mr. Sane,
rock mass strength is a general technical terms which cannot be applied to every petro-physical or sedimentological problem. For example, an alternating sequence of clay and sand resulting in a sort of layer cake-structure is favorable in case of seismic effects due to the buffering or moderating effect which the argillaceous material exerts on the lithology. In contrast to this situation, the rock strength is weakened as fluvial erosion affects the same lithology in a cut bank of a meandering drainage system, because of the low resistance of argillaceous material to the impact of erosion. The entire rock sequence gets undercut and collapses.
Regards
H.G.Dill
Dear Mr. Sane,
The "lithology" will definitely influence the ultimate strength of the "rock mass" that is the aggregate material composed of both intact rocks and any associated discontinuities such as joints, faults, and bedding planes.
I am attaching Chapter 2 of Dr. Palmstrom's PhD thesis in which you will find useful fundamental information regarding rock mass and associated terminology/definitions.
I hope this will be helpful for you.
Masoud
Dear Mr. Sane
Since you faced with a problem in which the strength of rock mass should be checked, gathering data about discontinuity and intact rock and weathering (rock mass properties) is essentially needed to prepare engineering geological classification of rock masses. Absolutely any change in mentioned above properties of rock can leads the change in rock mass properties(base of engineering geological classification). In a single lithological stratum the rock mass properties may changes. In this condition if the rock mass properties remarkably changes, engineering geologists classify this stratum (geological unit) in engineering geological units (more than one).
You should know about how mach the stress change penetrate into beneath rock mass due to your structure (engineering loading). The stress bulb penetrates in each types of geomaterial you should know about its engineering behavior against the amount of stress change.
In your case you should classify the rock mass and checking the penetration of stress in ground and determine the amount of stress change received by each types of geomaterial.
Good Luck.
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