基于优化组合赋权的可拓学磷矿山岩体质量评价

Evaluation of Rock Mass Quality of Phosphorite Mines by Topology Based on Optimal Combination Weight

为解决岩体质量评价相邻等级之间指标参数模糊不确定性问题,引入可拓学理论,提出基于优化组合赋权的可拓学岩体质量分级模型,对昆阳二矿磷矿山地下开采的岩石进行质量评价。首先,根据矿山地质特征选取岩石单轴饱和抗压强度(Rc)、岩石质量指标(RQD)、节理间距(Jd)、结构面条件(Jf)、地下水状态(W)和地应力影响系数(Z)6个影响指标,将每个指标划分为5个等级;然后通过改进的层次分析法和熵权法分别确定指标的主观和客观权重,引入矩估计法对主客观权重进行优化组合;最后应用修正的RMR法和Q系统法对岩体质量进行评价,将分级结果与基于优化组合赋权的可拓学岩体质量分级结果进行比较。研究表明:5个待评价岩体中,除上矿体N3的模型分级结果与修正RMR法存在差异之外,其余岩体的分级结果与修正RMR法相同,使用Q系统法的评价结果整体偏低。此外,该模型可得出岩体质量等级偏向于相邻等级的程度,分级结果符合昆阳二矿磷矿山生产勘探地质报告岩体质量范围,比修正RMR法和Q系统法更加准确,验证了本文方法的可靠性,为地下矿山开采提供了技术支撑。

In order to solve the problem of fuzzy uncertainty of index parameters between adjacent grades of rock quality evaluation,the theory of topology was introduced and the topological rock mass quality grading model based on optimal combination weight was proposed to evaluate the quality of rocks in underground mining of the phosphate mine in Kunyang No.2 mine.According to the geological characteristics of the mine,six influence indexes,namely,uniaxial saturated compressive strength of rock(Rc),rock quality index(RQD),joint spacing(Jd),structural surface condition(Jf),groundwater status(W)and geostress influence coefficient(Z)were selected,and each index was divided into five grades.Then,the subjective and objective weights of the indicators were determined by the improved hierarchical analysis and entropy weight methods,respectively,and the moment estimation method was introduced to optimize the combination of subjective and objective weights.Finally,the modified RMR method and Q-system method were applied to evaluate the quality of the rock mass,and the grading results were compared with the quality classification results of the rock mass based on the optimal combination weights.The results show that,among the five rock masses to be evaluated,the evaluation result for the upper ore body rock is ClassⅡ,with a characteristic value of 2.57,indicating good rock mass quality and certain self-stabilizing ability.It is determined that the support method of anchor spraying and hanging net should be adopted.For the lower ore body,the characteristic value is 3.68,indicating that the rock mass quality is approaching ClassⅣ,and the stability of the surrounding rock in the roadway is poor.Immediate initial spraying should be carried out after the excavation of the roadway to control the deformation of the surrounding rock,followed by the use of the anchor spraying and hanging net support method.There are differences in the grading results of the upper ore body N3,and the grading results of the rest of the rock bodies by the proposed method are the same as those of the modified RMR method.The overall low evaluation results using the Q-system method are caused by the failure to take into account the role of geostress and the discontinuity in the grading between the grades.In addition,the model is able to determine the degree to which the rock mass quality grade leans towards the adjacent grade.The classification results are consistent with the geological exploration report of the Kunyang No.2 mine,and are more accurate than the modified RMR method and Q-system method,validating the reliability of the method proposed in this paper and providing technical support for underground mining.