Then, the goaf was classified according to the geometric parameters.
Yuejin Zhou, Xiaoding Xu, Xiaotong Li, Meng Li, Yugui Yang 2018, 'Study on Catastrophe Instability of Support System in Gypsum Goaf Based on EnergyDissipation Theory', Advances in Civil Engineeringhttp://dx.doi.org/10.1155/2018/4293584. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The confined water progressive intrusion height reaches the maximum on the edge of the goaf.
Haifeng Lu, Duoxi Yao, Dan Shen, Jiyang Cao 2015, 'Fracture mechanics solution of confined water progressive intrusion height of miningfracture floor', International Journal of Mining Science and Technologyhttp://www.sciencedirect.com/science/article/pii/S2095268614001876. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Then, grouting injection was proposed to reduce the old goaf deformation under the tunnels.
Peixian Li, Lili Yan, Dehua Yao 2019, 'Study of Tunnel Damage Caused by Underground Mining Deformation: Calculation, Analysis,and Reinforcement', Advances in Civil Engineeringhttp://dx.doi.org/10.1155/2019/4865161. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Gateway-and-pillar goaf of a single layer has a range of influence of 9 m vertically.
Hongsheng Tu, Shihao Tu, Xiaogang Zhang, Zhaoxin Li, Shuai Jia 2014, 'Technology of back stoping from level floors in gateway and pillar mining areas ofextra-thick seams', International Journal of Mining Science and Technologyhttp://www.sciencedirect.com/science/article/pii/S2095268614000093. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
This can induce excessive deformation of roadway near the goaf.
Bin Yu 2016, 'Behaviors of overlying strata in extra-thick coal seams using top-coal caving method',Journal of Rock Mechanics and Geotechnical Engineeringhttp://www.sciencedirect.com/science/article/pii/S1674775516000020. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Rather, mining-induced fractures in the goaf should be utilized for gas extraction.
Jie Cao, Wenpu Li 2017, 'Numerical simulation of gas migration into mining-induced fracture network in thegoaf', International Journal of Mining Science and Technologyhttp://www.sciencedirect.com/science/article/pii/S2095268617303531. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Step subsidence and cracks, which indicate severe damages, were observed on the ground surface above the goaf.
Hongzhi Wang, Dongsheng Zhang, Xufeng Wang, Wei Zhang 2017, 'Visual Exploration of the Spatiotemporal Evolution Law of Overburden Failure and Mining-InducedFractures: A Case Study of the Wangjialing Coal Mine in China', Mineralshttp://www.mdpi.com/2075-163X/7/3/35. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Extraction of a coal seam which lies not far below a heating goaf can be a major safety challenge.
Gang Wang, Jun Xie, Sheng Xue, Haiyang Wang 2015, 'Mining a coal seam below a heating goaf with a force auxiliary ventilation systemat Longhua underground coal mine, China', International Journal of Mining Science and Technologyhttp://www.sciencedirect.com/science/article/pii/S2095268614001785. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The effect of controlling strata movement in solid filling mining depends on the filling rate of the goaf.
Jian Sun 2017, 'Mechanics criterion and factors affecting overburden stability in solid dense fillingmining', International Journal of Mining Science and Technologyhttp://www.sciencedirect.com/science/article/pii/S2095268617302343. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The tests took into account methane emissions from the mined coal and from the goaf with caving.
Magdalena Tutak, Jarosław Brodny 2018, 'Analysis of the Impact of Auxiliary Ventilation Equipment on the Distribution andConcentration of Methane in the Tailgate', Energieshttps://www.mdpi.com/1996-1073/11/11/3076. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)