Study On Deformation And Damage Of Upper Entry With Sixth Coal-seam Mined In Chaochuan Coal Mine

The mining of underlying coal-seam will inevitably affect the entry in the overlying strata. Find out the deformation & damage law of upper entry with mining of the working face below, will help to locate the damage place and predict the damage extent of the entry in advance, design underlying seam mining plans and establish maintenance & reinforcement measures of the entry.In this thesis, the effect of the sixth coal-seam mining on the upper entry in Chaochuan coal mine was mainly focused on. Firstly, based on the analysis of factors influencing the stability of the entry, the stress and displacement of the surrounding rock, and the distribution of law of the plastic zone were analyzed by using the FLAC3D, when the relative positions of the entry and its caving zone were different or the working face below were advancing. Secondly, the developing and distribution law of the overlying rock, influenced by its underlying coal-seam mining, were studied by similar simulating models. Thirdly, Based on the observation data of movement & deformation of the return-air way throughout the mining of the 21020 working face, the causes of movement & deformation under arch walling support were analyzed, and the relationship between the deformation & damage extent of arch walling support and the horizontal deformation value was summarized. Lastly, during the mining of underlying working face and after, the damage scope and extent of arch walling of the main haulage roadway were predicted, and the places where the surrounding rock deformed seriously were located. Meanwhile, some suggestions of corresponding technical measures of mining under main haulage roadway are put forward.The results show that once the mining of underlying working face is finished, the main haulage roadway will be within the curve subsidence zone. The strata which the main haulage roadway Locates will remain intact, unless locate near the area of open-off cut and terminal line or near the goaf boundary, which will probably get destroyed. With the original support system, the main haulage entry can not keep stable. However, as long as appropriate reinforcement and support are implemented to the surrounding rock of the main haulage roadway, and corresponding technical measures of mining are adopted, its stability can be guaranteed.