地下洞室岩爆预测灰色最优归类模型研究

Prediction of Rock Burst of Underground Cavern Based on Grey System Optimal Theory Model

在灰色关联分析和模糊识别原理的基础上,运用最小二乘法构造目标函数,选取影响岩爆的主要因素洞壁围岩最大切向应力σt、岩块单轴抗压强度σc、岩爆岩石的脆性指数K u、应力下降指数Kσ、岩石的弹性能量指数K w,并将σt/σc、K u、Kσ和K w作为评价影响因子进行关联分析,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灰色最优归类数学模型。模型运用了动态权重计算方法和综合评判指数的概念,充分考虑了评价标准指标的离散性。利用该模型对四川某水工隧洞3个断面围岩岩爆发生的可能性及烈度等级进行了预测,获得了较为客观的评价效果,表明所采用的地下洞室岩爆烈度预测方法是合理、有效的。

Rock burst 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 rock burst can provide the reference for engineering risk analysis report and take preventive measures. Based on the principle of grey correlation analysis and fuzzy model identification, a new grey system optimal theory model was established to predict rock burst occurrence. Some main control factors of rock burst, such as the maximum tangential stress of the cavern wall σt , the uniaxial compres- sive strength σc, rock brittleness index Ku and stress index K,, and the elastic energy index Kw of reck were chosen in the analysis. Four factors in- eluding σt/σc ,Ku ,Ku and K, were regarded as the evaluating indices. And rock burst intensity was classified as the non-rock burst, slight rock burst, medium rock burst and serious rock burst in the prediction model. The dynamic weight calculation method and comprehensive evaluation in- dex concept was used to give enough thought to discrete variable of evaluation index. By using the model of a hydraulic tunnel in Sichuan X, Y, and Z engineering sections of the possibility of rock burst in surrounding rock and the level of intensity was forecasted. The objective evaluation of the effect shows that the intensity of rock burst in underground caverns adopted by the prediction method is reasonable and effective.