Study on constraint degree calculation of frozen shaft inner wall mass concrete

Abstract

Based on the circle-shaped air shaft of Hong Qing-He coal mine located in Inner Mongolia China, the thermal-mechanical numerical model of frozen shaft inner wall mass concrete was established under complex thermal-mechanical boundary, including internal heating, external cold source, friction constraints, above shaft load and lateral pressure. The evolution characteristics of temperature-displacement field of inner wall were analysed. According to numerical simulation results, the constraint degree at the middle section of inner wall concrete is calculated. In the early stage (0-10d), the constraint degree of inner wall fluctuates within 60-99% as curing time goes. Three protection measures to delete confinement degree of mass concrete shaft wall were proposed, including (1) Reducing the friction between inner and outer walls; (2) Reducing hydration heat release of mass concrete; (3) Reducing the temperature difference between inner and outer walls during curing.