The select of assurance coefficient is a problem that is often met in mechanical design. How to reasonably select it is a basic subject.

安全系数的选取是机械设计中普遍遇到的问题，合理选取安全系数是机械设计中的一项基本课题。

The roof management, roof pressure computing, assurance coefficient checking are introduced. Three kinds of protecting methods of working face management are expounded.

从顶板管理、顶板压力计算、 安全系数校核方面进行了介绍，并且在大倾角工作面三防措施管理方面进行了详细的阐述。

The utility model has the advantages that the stability of the structure is good, the assurance coefficient is high, the anti-corona effect is good and the interchangeability of wires is good.

本实用新型结构稳定性佳， 安全系数高，防电晕效果和导线互换性好。

Factually there is no assurance for ductility in this coefficient. Furthermore, the seismic force is comparatively lower in design than in fact. Both of them necessarily increase the seismic risk.

实际规范中并没有延性构造保证，加之我国当前设计地震作用相对偏低，更增加了地震破坏的危险性。