Study on the Reasonable Rise-Span Ratio of Crown for Underground Powerhouses

In underground powerhouses' construction, the stability evaluation of the surrounding rock of underground caverns is a fundamental problem. In this paper, the influence of different rise-span ratio and lateral pressure coefficient towards the stability of crown of surrounding rock is studied. On the basis of the maximum tensile criterion, the stability of crown of surrounding rock is evaluated and the predicator formula of reasonable rise-span ratio is proposed. The paper comes to the conclusion that when rise-span ratio is set, compressive stress at the top of crown decreases when lateral pressure coefficient goes down; when lateral pressure coefficient is set, compressive stress at the top of crown decreases when rise-span ratio goes down. With appropriateness and reliability, the prediction formula of reasonable rise-span ratio guarantees the stability of surrounding rock of crown and provides scientific foundation for the preliminary confirmation of reasonable rise-span ratio of crown.