考虑水平荷载的采空区群系统灾变失稳模型

Catastrophic Instability Model of Goaf Group System Considering Horizontal Loads

为了研究采空区群系统的灾变失稳,将顶板简化为弹性薄板,矿柱简化为在长期荷载作用下会产生蠕变损伤的Poynting-Thomson体,考虑水平荷载和竖直荷载的共同作用,结合流变理论和燕尾突变建立采空区群顶板—矿柱系统灾变失稳模型。计算出模型突变时顶板中心的下沉量,矿柱有效支撑面积与顶板面积的比值,以及模型从开始到发生突变的时间,以广西盘龙铅锌矿为工程实例进行验证,得出盘龙矿采空区群系统的稳定时间与实际情况相符,验证了该模型的可靠性和实用性。同时,研究了各影响因素对采空区群系统稳定性的影响,为采空区群系统稳定性分析提供了新思路和新方法。

The underground mining of the mine has formed a large number of goaf groups,when these goaf groups reach a certain scale,it is likely to generate large-scale catastrophic ground pressure activities,and cause huge losses. Therefore,the stability analysis of the goaf group system is of great significance for the safe production of mines. In order to study the catastrophic instability of the goaf group system,the roof and the pillar are simplified as an elastic plate and a Poynting-Thomson body with creep damage under long-term loads, respectively.Considering the combined effect of horizontal and vertical loads,the catastrophic instability model of roof-pillar system in goaf group is established by combining rheological theory with swallowtail catastrophe. Due to the creep damage and weathering of the pillar,the effective support area of the pillar is gradually reduced,the center subsidence of the roof is gradually increased.When the center disturbance of the roof is increased to a certain value,the connection type of the roof is changed from fixed end to simple support,the stage when the connection type of the roof is fixed end is named the first stage.When the center disturbance of the roof is then increased to another value,the connection type of the roof is changed from simple support to free end,the stage when the connection type of the roof is simple support is named the second stage.And the stage when the connection type of the roof is free end is named the third stage.When the effective support area of the pillar is reduced to a certain value,the catastrophic instability of the model will happen.Supposed the model is in the first stage,the center subsidence of the roof when the catastrophe happens was calculated by using swallowtail catastrophe theory. By combining the rheological theory the stage when the catastrophe of the model happens can be judged,and then the ratio of pillar effective support area to roof area when the catastrophe happens was calculated. Finally the time from the start to the occurrence of catastrophe can be calculated by using the rheological theory.According to the ratio of pillar effective support area to roof area,the criterion for the catastrophic instability of the model was drawn from the calculation results,which provides a basis for the safe mining of the pillar.It is validated with the project example of the Panlong lead-zinc mine in Guangxi.The settling time of the goaf group system is consistent with the actual situation,which verifies the reliability and practicality of this model.The influence of horizontal loads,roof size,roof bending stiffness,roof thickness,vertical loads and initial elastic modulus of the pillar on the stability of the goaf group system is studied,which provides a new idea and method for the stability analysis of the goaf group system.The research shows that when roof size and vertical loads increase,the center subsidence of the roof gradually decreases and the ratio of pillar effective support area to roof area gradually increases when the catastrophe happens,the settling time of the goaf group system gradually decreases.When lateral pressure coefficient,roof bending stiffness and roof thickness increase,the center subsidence of the roof gradually increases and the ratio of pillar effective support area to roof area gradually decreases when the catastrophe happens,the settling time of the goaf group system gradually increases.When initial elastic modulus of the pillar increases,the center subsidence of the roof has no change and the ratio of pillar effective support area to roof area gradually decreases when the catastrophe happens,the settling time of the goaf group system gradually increases.