陷落柱突水模式及理论判据

WATER INRUSH PATTERNS AND THEORETIC CRITERIA OF KARSTIC COLLAPSE COLUMNS

不论岩体结构如何,地下水总是寻找采掘小区域内的构造软弱带,突破其中的关键部位(层),而形成突水。大量防治水实践和理论证实,突水通道一般呈横截面积有限、形状各异、类似陷落柱的柱体管道,因此,可以将煤矿突水‘柱体突水通道’设想为力学中的‘厚壁筒’,其顶底板突水类似‘筒盖’破坏失稳,煤柱侧壁突水则与‘筒壁’破坏失稳相似,而突水通道中的地下水压力和围岩地应力即为厚壁筒的内外压力;以‘柱体突水通道’和‘厚壁筒’的完全吻合为基础,将突水通道概化为‘柱体突水通道’统一模式,并建立其‘厚壁筒’力学模型。在利用模型进行突水条件分析时,应用结构分析的剪切破坏理论方法,并对其中的力学条件和推导过程作了适当简化,由地下水压力突破构造软弱带内关键层时的极限平衡状态,得到了简单实用的突水理论判据,可以有效预测突水部位及突水与否,指导防治水工作。范各庄2171综采工作面特大突水模型的建立及突水理论判别的实际计算表明,‘柱体突水通道’突水模式概化准确,‘厚壁筒’力学模型切实可行,突水理论判据正确,且切合实际。

Wherever the rock mass structures are located,groundwater always permeates through weak structure zones and may break through a key stratum and burst abruptly into working faces and form water inrush. It is shown by the theories and practice of water inrush prevention that the water inrush paths are generally in forms of ‘column pipelines’similar to karstic collapse columns of finite cross section area and different shapes,such as circular,ellipse,trapeziform,etc. Therefore,column pipelines of water inrush in coal mine areas can be imaged as‘thick wall canister’in terms of mechanics,the water inrush from roof and floor as‘lid failure of thick wall canister’,the water inrush from lateral walls of coal columns as‘lateral wall failure of the canister’,and hydraulic pressure and rock stress in the paths of water inrush as inner and outer pressures of the canister,respectively. Based on the imagination between column pipeline of water inrush and thick wall canister,the former can be generalized as column pipelines of uniform patterns,and simulated with mechanical models of thick wall canisters. When conditions of water inrush are analyzed with this model,shear failure theory in the structure analysis can be employed and mechanics analysis of models is reasonably simplified. The criteria of water inrush can be induced by a limit balance between the hydraulic pressure and shear of strata. The water inrush possibilities and locations can be effectively predicted and prevent in practice. It is indicated by an example of a very large water inrush volume on the 2171 working face,Fangezhuang mineral ltd.,that generalized water inrush patterns are correct, the models of thick wall canisters can be applied in practice and proposed criteria are correct and agree well with mining practice.