Study on sidewall support technology of pier pillar typegateway retained along goaf in Wutongzhuang Mine

In order to reduce the coal pillar lost of the coal mining face and to release the tension relationship of the gateway driving and the coal mining operation, based on the theoretical analysis and the site measured information, the paper provided a gateway retained along goaf technical method with the support (pier pillar) of the self suitable loaded gateway sidewall. With the establishment of the surrounding rock model of the gateway retained along goaf, a theoretical calculation formula of the sidewall support resistance was derived. With the monitoring and measure of the mine site strata pressure, the paper had an analysis and study on the deformation characteristics of the gateway retained along goaf during the coal mining period and the pier pillar stressed and deformation characteristics. The results showed that in the pier pillar, gateway retained along goaf, the max deformation values of the roof and floor of the gateway and the two sidewall deformation value would be 400 and 310 mm individually. After the deformation, the cross section of the gateway could fully meet with the space requirements of the ventilation and the gateway gas drainage. The max pressure of the pier pillar was 25.4 MPa and the max shrink value of the pier pillar was 256 mm. With the loading capacity scope of the pier pillar, the requirements of the initial roof cutting and the late support also could be met and the yield pier pillar support would have good gateway retained effect in the gateway retained along goaf.