A review of stress distribution in circular tunnels

In this paper, a review of stress distribution in circular tunnels is presented. Given that there are many different theories and methods on how to distribute stress around the tunnel, some of which are challenging. This led to a more accurate comparison. The research method in this article is based on reviewing and comparing conventional methods in the articles of researchers in this field. The results of this research are shown in comparative tables of different methods. In general, in the rocky and soil masses in the depths of the ground, stresses called in situ stresses act. The main cause of in situ stresses is the weight of the upper classes and the tectonic activities of the region.Understanding the status of inductive and inductive stresses is one of the essential requirements of tunnel design and other underground structures because in many cases the inductive stresses may exceed the rock resistance level and, if not thought through, may damage the structure. This perturbation of the in situ stress condition only extends to a certain distance from the tunnel axis, which is called the radius of impact, and beyond that, the stress situation remains intact. In addition to the shape and dimensions of the tunnel, the manner and velocity of tunnel digging as well as the staging of the various sections (in cases where tunnel sections are dug in several steps) are also effective in arranging the induced stresses and the drilling system must be designed to minimize instability.