深井采动巷道围岩流变和结构失稳大变形理论

Large deformation theory of rheology and structural instability of the surrounding rock in deep mining roadway

与浅部相比,深部巷道特别是千米深井采动巷道,地应力高、采动影响强烈,导致巷道围岩变形大、持续时间长、破坏严重,目前的理论不能科学解释深井采动巷道的围岩劣化、大变形与破坏机理。深部开采条件下的巷道围岩大变形破坏理论已经成为煤炭深部开采面临的重大课题之一。为此,采用现场调研与试验、实验室实验、数值模拟和理论分析等方法,从应力强度比出发,并考虑偏应力和梯度应力,提出了采动系数的概念;从力学本质和工程应用的角度明确了巷道强采动和大变形的概念,探讨了其科学内涵,并初步提出确定了强采动和大变形的量化的评价方法;在此基础上,基于深井强采动巷道围岩所处应力环境及其大变形特征,初步提出了深部采动巷道围岩流变和结构失稳大变形理论框架。其核心思想是巷道围岩结构运动、围岩劣化、梯度应力和偏应力诱导围岩裂隙扩展、软岩流变与结构性流变大变形、破裂岩体长时扩容;基本问题包括深井采动巷道围岩应力路径、考虑应力路径的偏应力和梯度应力对巷道围岩的作用机理、巷道围岩锚固承载结构流变大变形、巷道围岩结构失稳大变形等。偏应力和梯度应力导致巷道浅部围岩张拉劈裂扩容和承载区围岩剪切滑动,且承载区围岩剪切滑动对浅部张拉劈裂围岩产生向巷道内的推力,扩容与推力导致浅部锚固体出现结构体滑移流变和整体性的挤入。由传统的软岩流变上升至软岩流变与锚固体结构性流变大变形。巷道围岩结构失稳大变形包括上覆岩层大结构失稳导致的整体移动大变形和松动圈内破裂岩体运动失稳大变形。提出的深部采动巷道围岩流变和结构失稳大变形理论从深部环境、深部岩体及强烈施工扰动相互作用出发,揭示深部巷道围岩应力场时空演变规律和大变形与破坏机理。

Compared with the shallow roadway,the deep roadway,especially the mining roadway in kilometer deep mines,has high in-situ stress and strong mining influence,which leads to the large deformation,long duration and serious damage of the surrounding rock of the roadway.The current theory cannot scientifically explain the deterioration,large deformation and damage mechanism of the surrounding rock of the deep mining roadway.The theory of large deformation and failure of roadway surrounding rock under the condition of deep mining has become one of the major issues facing the deep coal mining.Therefore,the concept of mining coefficient is put forward based on the stress intensity ratio,partial stress and gradient stress,field investigation and experiment,laboratory experiment,numerical simulation and theoretical analysis.From the point of view of mechanical essence and engineering application,the concept of strong mining and large deformation of roadway is defined,its scientific connotation is discussed,and the quantitative evaluation method of strong mining and large deformation is preliminarily put forward.On this basis,based on the stress environment and large deformation characteristics of the surrounding rock of the deep mining roadway,the theoretical framework of the rheology and structural instability of the surrounding rock of the deep mining roadway is proposed.Its core idea is the structural movement of the surrounding rock,the deterioration of the surrounding rock,the crack expansion induced by the gradient stress and deviatoric stress,the large deformation caused by the rheology and structural rheology of the soft rock,and the long-term expansion of the fractured rock mass.The basic problems include the stress path of the surrounding rock of the deep mining roadway,the action mechanism of the deviatoric stress and the gradient stress considering the stress path on the surrounding rock of the roadway,and the anchorage bearing structure flow of the surrounding rock of the roadway large deformation,instability of surrounding rock structure and so on.Partial stress and gradient stress lead to the expansion and shear sliding of the surrounding rock in the bearing area,and the shear sliding of the surrounding rock in the bearing area produces thrust to the roadway,and the expansion and thrust lead to the structural slip,rheology and integrity extrusion of the shallow anchorage.The traditional rheology of soft rock upgrades to the rheology of soft rock and the structural rheological deformation of anchor solid.The large deformation of the surrounding rock structure of the roadway includes the large deformation of the whole movement caused by the large structure instability of the overlying strata and the large deformation of the movement of the fractured rock mass in the loosening circle.Based on the interaction of deep environment,deep rock mass and strong construction disturbance,the theory of rheology and structural instability of surrounding rock in deep mining roadway is put forward,which reveals the temporal and spatial evolution law of stress field and the mechanism of large deformation and failure of surrounding rock in deep mining roadway.