Study On Assessment Methods For Safety Of Mined-out Area Based On Relative Membership Degree Theory

Safety is always an important theme in the evolution of human being. Work Safety is relative to the safety of people's lives and property. It is also relative to the development of national economy and the stability of society. Theories of scientific development and community in harmony call for people oriented. By the Law of the People's Republic of China on Work Safety and other provisions in relevant laws and administrative regulations were enacted by nation's organization, work safety supervision and accident investigation were enhanced. Safety management by engineering technology method must be promoted also, which can spot hidden dangers and prevent accident that may jeopardize safety.By carrying out research on some conceptions about safety, safety assessment is an important process in work management. Comparing many assessment methods, a new safety assessment model was chosen to use for mined-out area risk evaluation.Based on knowledge about risk of mined-out area, an assessment index system was established. Nonlinear fuzzy handling methods were adopted in quantification of assessment indexes and in handling of characteristic value classification. Relative membership degree and relative membership function were led into general fuzzy assessment model. By usage of generalized distance of weight, assessment results are more dispersed, so that the risk grades are easier to be distinguished. Most subordinated principle was substituted by fuzzy characteristic quantity of risk grade as expression mode. Assessment results have better reliability and rationality. Fuzzy entropy can be assessment indexes for dispersed extent of subordinated vector of risk grade. The less the fuzzy entropy is, the less indefinable the risk grade system is, the more dispersed the subordinated vector is, the better the assessment methods are.Calculating with example of the 22 mined-out areas by the method, risk grades were affirmed. The applicability of the proposed safety assessment methods in this paper was validated as well.