Abstract
Support crushing and roof fall accidents frequently occur in the large mining height stope covered by the thin bedrock and large-thick alluvium (TBLA). A comprehensive method including field monitoring, numerical modelling, and theory analysis was performed to investigate the strata movement and its induced ground behaviors of a deep-buried stope under TBLA. The filed measurement results indicated that strong roof periodic weighting phenomenon occurred regularly at an interval of 18–23 m during panel 3301 retreating. During weighting period, dynamic characteristics of hydraulic supports are prominent and characterized by high safety valve opening rate and poor working conditions including tilt down operation and excessive end distance. Additionally, numerical modelling results revealed that the thickness of bedrock affects the movement behaviors of the roof strata and its generated spatial structure significantly. Based on the above results, an integrated control measure was proposed and successfully applied to the test site.
Highlights
Coal resources are rich in reserves and have obvious regional distribution characteristic in China
According to the analysis of geological conditions, ground response behavior law, and roof strata spatial structure during 3301 panel retreating, the mechanical principles of stability of the thin bedrock could be summarized as follows: 1 when stope is covered by the thin bedrock and large-thick alluvium, the
Based on the above analysis, it can be inferred that, in the large mining height stope covered by thin bedrock and largethick alluvium (TBLA), the key technology to control the stability of surrounding rock adjusts the operating mode of hydraulic supports to reduce dynamic load influence caused by sliding and instability of roof strata. e main measures on adjusting the operating mode of hydraulic support are as follows: (1) Reasonable support working resistance: according to analytical and numerical modelling results, it can be inferred that roof strata spatial structure type depends on the thickness of bedrock, and the hydraulic support needs to bear more loads when bedrock thickness is small
Summary
Coal resources are rich in reserves and have obvious regional distribution characteristic in China. Compared with the coal mines in Western China, coal mining in East China encounters new challenges, such as large burial depth, thin bedrock, and large-thick alluvium [5,6,7,8] Many disasters, such as water inrush, support crushing, and coal mass leakage at the end face, occurred in the field. There are few case studies on the ground behaviors of a large mining height stope, which has the characteristics of large buried depth, thin bedrock, and thick alluvium in Juye mining area. E above complex geological condition resulted in many difficulties in the coal mining activities Various accidents such as support crushing and end face leaking roofs occurred frequently in the field. E objective of this paper is to investigate the roof strata movement process and its induced ground behaviors of a stope covered by TBLA in the Juye mining area.
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