圆形硐室岩爆的折迭突变模型

Fold catastrophe model of circular tunnel rockburst

均匀围压下圆形硐室岩爆是传统意义上的软化区内岩环经过塑性变形局部化阶段完成的。当处于极限状态的塑性变形集中区承载能力下降时, 岩环中相对完好部分以弹性方式卸载,当后者释放的弹性能超过前者塑性变形所耗散的能量时便发生岩爆。简捷地通过等效应力σi 和等效应变εi 关系建立突变模型对硐室岩爆进行了分析, 将状态变量εi 用软化区半径 R来表示。分析表明: 岩爆发生条件与硐室岩体的升降模量比 E λ 和岩体裂隙发育程度l L 的乘积有关; 对于特定冲击倾性的岩体,存在对应的临界软化区深度 Rj , 即软化区深度达到 Rj 时便发生岩爆;还给出硐室岩爆释放地震能等计算式,岩爆释放的地震能量级则与硐室软化区深入程度有关。

The circular chamber rockburst under uniform confined pressure occurs and ends by the phase of the plastically deforming localization of rock ring in softening zone on the traditional meaning. The carrying force in the concentration zone of plastic deformation reduces under limiting state, but comparatively intact part in rock ring unloads by way of elasticity. The rockburst occurs when the elastic energy released by latter is more than the dissipated energy by former in plastically deforming form. The catastrophe model of tunnel rockburst is established forthright by the relationship between equivalent stress σi and equivalent strain Εi, and state variable Εi is expressed by softening zone radius R. Analysis shows: The occurrence condition of rockburst has relations with the product of the rock's ratio of elastic modulus to descending modulus and crack growth degree of rocks. To rock with specific rockburst tendency, there is corresponding critical depth of softening zone, Rj, i.e. rockburst occurs when softening zone depth reaches Rj. The amount of earthquake energy that released by rockburst has also relations with the deepening degree of softening zone.