Arabian Journal of Geosciences

, 11:554 | Cite as

Experimental study on excavating strip coal pillars using caving zone backfill technology

  • Weibing Zhu
  • Shengchao Yu
  • Dayang Xuan
  • Zhenjun Shan
  • Jialin XuEmail author
Original Paper


Strip mining was the major method to control surface subsidence when mining under buildings in China; however, its coal recovery ratio was only 30 to 50%, resulting in a large amount of coal resource waste due to the retained strip coal pillars. As such, it is of important significance to recover the retained pillars while guarantee the safety of the buildings at surface. In order to address this issue, excavating strip coal pillars using caving zone backfill technology was proposed in this study. The process of this technology was to grouting backfill the original strip caving zones using high-water content material at first, creating a combined backfill body of caved gangue and high-water content material, the backfill body acted as the temporary support. Then the retained pillars were excavated and the newly produced caving zones were backfilled with one interval, which effectively prevented the movement and deformation of the strata. The backfilling system and technology were designed and trailed to excavate the retained pillars at mining area 911 in Bucun colliery. It was found that the backfilling rate reached 96.8 to 98.7% in the original caving zones, the backfilling body in caving zones was highly compacted, and the maximum surface subsidence was only increased to 67 mm with no growth in the failure depth of floor. The retained coal pillars in three of the mining areas were safely excavated and the safety of buildings on the ground was preserved.


Strip mining Caving zone backfill Strip coal pillar Surface subsidence Green mining 


Funding information

The financial supports from the State Key Research Development Program of China (2016YFC0501100) and the Fundamental Research Funds for the Central Universities (2015XKMS098) are greatly appreciated.


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Copyright information

© Saudi Society for Geosciences 2018

Authors and Affiliations

  • Weibing Zhu
    • 1
    • 2
  • Shengchao Yu
    • 1
  • Dayang Xuan
    • 1
  • Zhenjun Shan
    • 3
  • Jialin Xu
    • 2
    Email author
  1. 1.Key Laboratory of Deep Coal Resource Mining, Ministry of Education of China, School of MinesChina University of Mining and TechnologyXuzhouChina
  2. 2.State Key Laboratory of Coal Resources and Safe MiningChina University of Mining and TechnologyXuzhouChina
  3. 3.School of Civil, Mining and Environmental EngineeringUniversity of WollongongWollongongAustralia

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