Keyword

Stress, Uniaxial compressive strength, Notch, Achaean basement complex, Madhyapara, Bangladesh 1. Lecturer, Department of Petroleum & Georesources Engineering, Shahjalal University of Science & Technology, Sylhet-3114, Bangladesh 2. Associate professor, Department of Geology & Mining, Rajshahi Uni

Abstract

In the present research the detail stress analysis has been carried out using Kirsch’s equation inscribing circular roof of the tunnel. A computer program using FORTRAN has been developed in order to calculate the stresses in and around the tunnel opening. It is observed from the analyses that the maximum principal stresses are found at the corner of the arc of the opening. At the corner compressive stress is active whereas tensile stress is prevails on the top of the roof. We compared the different stresses whose are active surrounding the Roadway tunnel with strength of the rock and try to predict the possible failure. Strength of rock of different categories is determined from laboratory tests and found that the rock strength are 105 Mpa, 70 Mpa and 40 Mpa of rock categories I, II & III respectively. It is mentioned that rock are categorized on the basis of joint spacing. According to the stress distribution, the stress-induced failure could be occurred around the corner of the arc at initial period of tunnel construction. The line of failure was determined using uniaxial compressive strength of rock and the maximum and minimum principal stresses. It is found that notches and failed region are larger in rock category-III


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