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Smart Structures and Systems
  Volume 25, Number 4, April 2020, pages 433-446
DOI: http://dx.doi.org/10.12989/sss.2020.25.4.433
 


Numerical simulation of the effect of confining pressure and tunnel depth on the vertical settlement using particle flow code (with direct tensile strength calibration in PFC Modeling)
Hadi Haeri, Vahab Sarfarazi and Mohammad Fatehi Marji

 
Abstract
    In this paper the effect of confining pressure and tunnel depth on the ground vertical settlement has been investigated using particle flow code (PFC2D). For this perpuse firstly calibration of PFC2D was performed using both of tensile test and triaxial test. Then a model with dimention of 100 m × 100 m was built. Acircular tunnel with diameter of 20 m was drillled in the middle of the model. Also, a rectangular tunnel with wide of 10 m and length of 20 m was drilled in the model. The center of tunnel was situated 15 m, 20 m, 25 m, 30 m, 35 m, 40 m, 45 m, 50 m, 55 m and 60 m below the ground surface. these models are under confining pressure of 0.001 GPa, 0.005 GPa, 0.01 GPa, 0.03 GPa, 0.05 GPa and 0.07 GPa. The results show that the volume of colapce zone is constant by increasing the distance between ground surface and tunnel position. Also, the volume of colapce zone was increased by decreasing of confining pressure. The maximum of settlement occurs at the top of the tunnel roof. The maximum of settlement occurs when center of tunnel was situated 15 m below the ground surface. The settlement decreases by increasing the distance between tunnel center line and measuring circles in the ground surface. The minimum of settlement occurs when center of circular tunnel was situated 60 m below the surface ground. Its to be note that the settlement increase by decreasing the confining pressure.
 
Key Words
    direct tensile strength; PFC2D; confining pressure; settlement; tunnel
 
Address
(1) Hadi Haeri:
State Key Laboratory for Deep GeoMechanics and Underground Engineering, Beijing, 100083, China;
(2) Vahab Sarfarazi:
Department of Mining Engineering, Hamedan University of Technology, Hamedan, Iran;
(3) Mohammad Fatehi Marji:
Mine Exploitation Engineering Department, Faculty of Mining and Metallurgy, Institution of Engineering, Yazd University, Yazd, Iran.
 

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