Study on the Evolution Law and the Orientation Criterion of a Plastic Zone in Rock Surrounding a Circular Roadway in a Three-Dimensional Non-Isobaric Stress Field

Abstract

The original rock stress field is mainly divided into the σHZ-dominant stress field, the σZ-dominant stress field, and the σH-dominant stress field. Via theoretical analysis, the plastic zone morphology and the orientation of roadway surrounding rock under a three-dimensional stress field are studied in depth, and the theory is verified by numerical simulation. The results show that in the σHZ-dominant stress field, the plastic failure mode changes from elliptical to quasi-circular to butterfly, and the optimized angle range of the roadway orientation is determined by three principal stresses. In the σZ-dominant stress field, the shape of the plastic zone transforms from butterfly to ellipse, the optimized angle range of the roadway orientation is 50–90°, and the butterfly hidden danger zone is in the 0–50° range. In the σH-dominated stress field, the shape of the plastic zone transits from ellipse to butterfly. The optimized angle range of the roadway orientation is 0–40°, and 50–90° is the butterfly hidden danger zone.

Radius solution of plastic zone in soft rock tunnel surroundings considering joint damage

“…conducted a theoretical analysis on the stress distribution of the surrounding rock considering strain softening based on the variation law of the cohesive force of the borehole surrounding rock, and determined the theoretical formula for the plastic zone radius 19 . To this day, scholars have made significant achievements in the theoretical research of the plastic zone of surrounding rocks [20][21][22] . but there are still some shortcomings: Firstly, a large number of studies have only focused on solving the radius of the plastic zone of intact rock masses, and there is relatively little research on rock masses with joints and cracks.…”