Investigating the effect of Beecher type fractures on tunnel displacement using the finite element method

Abstract

It is very important to study the displacement of underground spaces in mining, civil and environmental projects. Investigating the rock mass behavior depends on the relative fracture knowledge joints in the rock mass. From another point of view, uncertainty and variability in the behavior of rock masses, which are a combination of natural and heterogeneous materials, are inevitable in engineering geology studies. In this article, using Phase2 software, the effect of different distributions of joints and fractures of the Beecher type on the displacement of tunnels and underground spaces was investigated using numerical modeling. Hence, by varying the geometrical parameters of the tunnel, joints and different distributions of normal, log normal, uniform and exponential fracture, its effect on the stability of the tunnel was simulated in 640 models. The results show that in all these simulations, the exponential distribution of fractures in Beecher's model has less effect than other distributions in the maximum displacement of the tunnel. While normal and log-normal distributions have the greatest effect on tunnel stability in most of the simulated models. On the other hand, with the increase of the density of the joints from the value of 0.8, the displacement of the tunnel does not depend on the density of the joints. According to the sensitivity analysis of different parameters and their investigation based on different distributions of Beecher-type fracture joints in connection with the stability of tunnels, it can be stated that only an average difference of 19% of the types of distributions is effective in the stability and displacement of tunnels, and it is suggested that experts And tunnel engineers and excavators in this field should focus studies on other parameters of tunnel stability and underground spaces.