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Rock Mechanics long term research program in CUET - Bangladesh

Chittagong University of Engineering & Technology abbreviated as CUET, is one of the prominent and prestigious degree awarding institute in the engineering education of Bangladesh. This University was created out of Engineering College, Chittagong, that was established in 1968. The Engineering College Chittagong, functioned as the Faculty of Engineering of the University of Chittagong. Through a Government Ordinance in 1986 the college was converted into an institution (BIT, Chittagong).

Among the Faculties of CUET, the Department of Petroleum and Mining Engineering (PME) offers Bachelor of Science in Petroleum and Mining engineering which is one the top university level programs among the engineering universities in Bangladesh. This discipline was founded in March 2010. This department is started under a 4-year project of Bangladesh government. The project implementation time is July 2009-June 2013. At present intake is 30 students per year. The department has now faculty strength of 7 including 2-part time teachers.

PME has recently implemented his Rock Mechanics Laboratory facilities with highly automatic triaxial equipment for research and investigation of short and long-time (i.e. creep tests) behaviour of rock core samples under uniaxial and triaxial stress conditions.

One of the most important tasks of rock-mechanical characterization is to determine the failure curves; failure criteria are required to estimate the behaviour of intact rock cores when subjected to different levels of overburden stresses.
Failure criteria are generally expressed by simple analytical formula that are obtained experimentally.
From different tests on intact rock cores (uniaxial and triaxial) carried out to the maximum strength under different stress conditions, it is possible to get experimental relationships

For determining a generalized hyperbolic envelope (e.g. the Hoek-Brown failure criterion, widely accepted for rock masses since 1980s), a minimum of three parameters are necessary: tensile strength, uniaxial compressive strength and the triaxial compressive strengths with different confining pressures, generally in the range between the geostatic stress and 50% of the uniaxial strength.

The solution proposed by Controls Group is the Advantest 9 Rock equipment, an automatic system designed to perform both stress and strain controlled uniaxial and triaxial tests on cylindrical samples constrained in Hoek cells.

Instead of performing several triaxial tests on different rock cores (with the same mechanical characteristics), the system allows to perform a single multistage triaxial test, where the cell pressure is increased once the sample is near failure: subsequent steps of increasing isotropic pressure are applied to the rock sample and for each of them the axial deviatoric stress is also increased under displacement feedback control, towards the failure conditions.
After failure, since the test is carried out under displacement control, similar automatic procedure is continued in reverse mode, by reducing the isotropic pressure, so that the residual strength can be measured for each step of decreasing pressure