Three-dimensional Numerical Simulation Of Shaft Wall Temperature Stress

Since 1987, there has been more than 80 shaft wall ruptures in mining area of Huanghuai, South China. During this nearly 20 years many researchers have been studying on the shaft wall rupture mechanism and lots of perspectives and understandings have come into being. However temperature stress studies on shaft wall were very limited, even ignored. We should strengthen temperature stress studies, and define its role in the shaft wall rupture. There are certain significances in both theory and practice.First, shaft temperature field is analyzed combining the three basic ways of heat transfer and details on the model of forced convective heat transfer and thermal - stress coupling theory are given. With Linhuan auxiliary mine shaft as the prototype, a geological model is built based on the geological environment and shaft wall ruptures. Then the physical and mechanical parameters, thermodynamic parameters and temperature data of the shaft wall and strata are analyzed and given. Considering many factors including seasonal temperature changes of the air, convective heat transfer between shaft wall and air and heat conduction between shaft wall and rock, the forced convection - heat conduction model and the Mohr-Coulomb constitutive model are used in FLAC^3D to simulate the corresponding relations between the temperature of shaft wall and the seasonal temperature changes which reached the dynamic law of temperature stress distribution in shaft wall.The above work shows that: (1) the temperature and stress in the shaft wall and strata cyclically change with the seasons affected by the seasonal temperature changes. Hysteresis Effect of temperature is remarkable and temperature stress delays about 10 days. (2) Above the mantlerock, the Vertical temperature stress in the shaft is dominating, and the Tangential stress is less, and the Radial stress is relatively negligible. The Maximum principal stress equal to Vertical stress approximately, which makes an angle of about 11.9°to 14.25°with the shaft axis. Under the mantlerock, the Tangential stress increases gradually and the Vertical stress goes slightly down. Therefore the Maximum principal stress comes to be controlled by the Vertical and Tangential stress together, which makes the angle increase to about 43.8°to 49.5°with the shaft axis. (3) From Apr to Oct the Maximum principal stress in the shaft is relatively concentrated, maintained above -4.0MPa, which is near the bottom aquifer and the interface with the mantlerock and the bedrock. It is above -7.0 MPa from Jun to Aug.