模糊概率模型在岩爆烈度分级预测中的应用

APPLICATION OF FUZZY PROBABILITY MODEL TO PREDICTION OF CLASSIFICATION OF ROCKBURST INTENSITY

岩爆是深部高地应力区岩石地下工程中的一种常见地质灾害,对其发生的可能性及其烈度分级预测是地下工程建设中亟待解决的重大课题之一。以模糊概率理论为基础,选取影响岩爆的一些主要因素,如洞壁最大切向应力σθ、岩石单轴抗压强度σc、岩石单轴抗拉强度σt以及岩石弹性能量指数Wet,并以σθ/σc,σc/σt和Wet作为评价影响因子,同时将岩爆烈度划分为无岩爆、弱岩爆、中岩爆和强岩爆4个等级,建立岩爆烈度分级预测的模糊概率模型。在此模型中,提出了模糊权重的概念,可充分考虑权重的模糊性。模糊概率模型不仅继承了经典模糊综合评判法的思想和优点,同时也克服了其在实际应用中评价影响因子权重取值的局限性,因而具有明显的合理性。应用该模型对冬瓜山深埋硬岩矿山、秦岭隧道工程以及某大型水电站地下厂房3个典型工程岩爆的实例分析表明,其预测结果与实际情况符合较好。为进一步考察该模型的可靠性与实用性,对国内外23个大型岩石地下工程实例进行计算分析,其预测结果与实际岩爆情况也相当吻合。由此可见,模糊概率模型为深部岩石地下工程岩爆预测问题提供了一种新途径。

Rockburst is a kind of dynamic instability phenomenon of surrounding rock in underground projects in deep high-geostress zone. The prediction of possibility and classification of rockburst are basic issues in many underground projects. Based on the fuzzy probability theory,a new fuzzy probability model is established to predict rockburst occurrence and its intensity. Some main control factors of rockburst,such as the maximum tangential stress of the cavern wall σθ,the uniaxial compressive strength σ cand the uniaxial tensile strength σ t of rock,the elastic energy index We t of rock,are chosen in the analysis. Three factors including σθ /σc,σ c /σt and We t are regarded as the evaluating indices. And rockburst intensity is classified as the non-rockburst,slight rockburst,medium rockburst and serious rockburst in the prediction model. In order to assess the index weight scientifically and to avoid the uncertainties while determining the index weight,the fuzzy weight is introduced into the rockburst prediction model. The fuzzy probability model not only holds the merits of classical fuzzy comprehensive evaluation method,but also overcomes its limitations in practice. Rockburst predictions of Dongguashan deep hard rock mine,Qinling Tunnel and an underground hydropower station are performed by this model. Furthermore,23 underground rock projects at home and abroad are also evaluated with the proposed method. The prediction results agree well with the practical records. It shows that the fuzzy probability model is reasonable and effective to predict the possibility and classification of rockburst in deep underground engineering.