A coupled experimental and numerical simulation of concrete joints' behaviors in tunnel support using concrete specimens

Fei Zhou, Vahab Sarfarazi, Hadi Haeri, Mohammad Hosein Soleymanipargoo, Jinwei Fu and Mohammad Fatehi Marji

Abstract

The experimentally tested modelled specimens were simulated by a two-dimensional particle flow code to study the behavior of rock mass surrounding a tunnel interacted with a nearby rock joint or discontinuity. The specially prepared specimens are tested in the laboratory and the measured results are provided. Then a numerical modelling of these tests is accomplished by a calibrated two-dimensional particle flow code to study the rock tunnel behavior while interacting with a neighboring joint. The two-dimensional discrete element code was calibrated using Brazilian tensile test. Then the modelled specimens are provided so that various configurations of tunnel cross sections and the neighboring joints were tested under uniaxial compression condition. This study showed that the tensile cracks are the most dominant mode occurred in these modelled samples. The wing cracks initiated from the joint tips when the joints interacted in a position less than that of the tunnel height. These cracks are then propagated and interacted with the tunnel ceiling. When the joint interacting the tunnel head and the interaction angle is negative the tunnel can be in a stable position considering the joints effect on its instability situation. But for positive interaction angles and the case of joint existing near the tunnel head, the wing cracks may initiate and propagate towards the tunnel ceiling. As the distance of joint from the tunnel ceiling is increased its effect on the tunnel instability is decreased because the failure stress is increased. The number of joints and their distance with the tunnel boundary (ceiling) have also a profound effect on the stability condition of the tunnel. The failure stress reached its maximum value for the increase from -30 to -60 degrees or increase from 30 to 60 degrees. The failure stress also decreased as the number of notches and their lengths increased. In all these interaction scenarios, the corresponding numerical and experimental values compared and it is concluded that the failure stresses are very close to each other which verified the accuracy and applicability of the proposed modeling technic.

Key Words

discrete element method; induced wing crack; interacted joint; tunnel; two dimensions

Address

Fei Zhou: School of Civil Engineering and Architecture, Hubei University of Arts and Science, Xiangyang City, Hubei province, China Vahab Sarfarazi: Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran Hadi Haeri: State Key Laboratory for Deep GeoMechanics and Underground Engineering, Beijing, 100083, China Mohammad Hosein Soleymanipargoo: Department of Civil Engineering, Semnan University, Semnan, Iran Jinwei Fu: School of Civil Engineering and Transportation, North China University of Water Resources and Electric Power, Zhengzhou, 450046, China Mohammad Fatehi Marji: Department of Mine Exploitation Engineering, Faculty of Mining and metallurgy, Institute of Engineering, Yazd University, Yazd, Iran

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