Non-uniform deformation mechanism and support technology of narrow coal pillar roadway

In order to solve the problem of non-uniform large deformation control of narrow pillar roadway,the narrow coal pillar roadway in Fenghui Coal Mine was used as the engineering background. The field survey,laboratory experi- ments,numerical simulation and theoretical analysis were used to study the stress and plastic zone distribution charac- teristics of surrounding rock of mining roadway under the influence of different coal pillar sizes. The deformation and failure laws of narrow coal pillar roadway and the movement characteristics of overlying strata structure were analyzed, and the mechanism of non-uniform deformation of narrow coal pillar roadway was revealed. Mining stress fields are su- perimposed,and results in a large abutment pressure;the structure of overlying strata is asymmetric,and causes a sig- nificant partial load effect;due to the small size and low strength of coal pillar,it is difficult to provide an effective sup- port for the roof;and the supporting scheme is symmetrically arranged,and poorly targeted,which are the main reasons for the non-uniform deformation of narrow pillar roadway. Based on the difficult control characteristics of surrounding rock in narrow coal pillar roadway,the differential support technology with “the change of roadway support mode,the enhanced support density and grouting modification of broken surrounding rock” is proposed to strengthen the control of local large deformation of surrounding rock to give a full play to the carrying capacity of surrounding rocks. On-site monitoring results show that the non-uniform deformation of narrow coal pillar roadway during the service is effectively controlled,the surrounding rock is very stable. The differentiated support technology has a high reference value for the same type of roadway surrounding rock control.