越界开采引起既有井筒垮塌的力学分析及修复实例

Mechanics analysis and repairment example of shaft collapse caused by the cross-border mining of nearby small coal mines

以某煤矿副立井井筒垮塌事件为背景,分析了立井井筒垮塌机理和修复方案。研究表明造成副井井筒垮塌主要是由于邻近小煤矿越界开采引起。结合越界开采扰动分析,建立了井筒力学模型,分析了立井井筒在均匀地应力和非均匀地应力作用下的受力情况,随不均匀侧压系数β增加,井筒不同应力极值位置处的应力差会增加,降低井筒的极限承载能力。利用FLAC-3D建模再现了越界开采引起的破坏过程,研究了不同保护煤柱尺寸条件下井筒变形和受力情况,指出当煤柱小于60 m时井壁变形加剧、趋于破坏。给出了采用水泥粉煤灰注浆和重造围岩方式对垮塌井筒进行修复的加固方案,修复后井壁应变监测表明修复后的井筒稳定性良好。

Based on the collapse of auxiliary shaft in a coal mine,the collapse mechanism and repairing scheme of shaft are analyzed.The results show that the main reason causing the collapse of the auxiliary shaft is cross-border exploitation of several nearby small coal mines.Combined with the perturbation analysis of cross-border exploitation,the mechanical model of shaft is established,and the force conditions under uniform and non-uniform ground stress are analyzed respectively.With the increase of the uneven lateral pressure coefficient β,the stress difference increases at different extreme value places of the shaft collapse,which affects the ultimate bearing capacity of the wellbore and is not conducive to the stability of the wellbore.Meanwhile,the process of damage of cross-border exploitation is reproduced by using FLAC-3D,the deformation and force condition of the shaft are studied under the condition of different protective coal pillars.When the protective coal pillar is less than 60 m,the deformation of the shaft is large.Under this condition,the shaft may lead to deformation and failure.Combined with the above research,the cement fly ash grout filling and the reconstruction of surrounding rock are put forward for repairing the collapse shaft.Through the monitoring and analysis of the shaft deformation,it is considered that the shaft has good stability after the implementation of the repairmen scheme.