Mechanism of stress distribution and failure around two different shapes of openings within fractured rock-like materials

Abstract

The complexity of a rock masses structure can lead to high uncertainties and risk during underground engineering construction. Laboratory tests on fractured rock-like materials containing a tunnel were conducted, and two-dimensional particle flow models were established. The principal stress and principal strain distributions surrounding the four-arc-shaped and inverted U-shaped tunnels were investigated, respectively. Numerical results indicated that the dip angle combination of preexisting fractures directly affects the principal stress, principal strain distribution and the failure characteristics around the tunnel. The larger the absolute value of the preexisting fracture inclination angle, the higher the crushing degree of compression splitting near the hance and the larger the V-shaped failure zone. With a decrease in the absolute value of the preexisting fracture inclination angle, the compressive stress concentration of the sidewall with preexisting fractures gradually increases. The types of cracks initiated around the four-arc-shaped tunnel and the inverted U-shape tunnel are different. When the fractures are almost vertical, they have a significant influence on the stress of the sidewall force of the four-arc-shaped tunnel. When the fractures are almost horizontal, they have a significant influence on the stress of the sidewall of the inverted U-shaped tunnel. The findings provide a theoretical support for the local strengthening design of the tunnel supporting structure.

Keywords

tunnel / fractured rock-like material / 2D particle flow code / crack initiation / stress distribution

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