Abstract
The changeable structure and movement law of overlying strata are the main contributor to the change of mining stress. Starting from the relevant theory of key stratum and particularly based on the theory of mine ground pressure and strata control, this research proposed a new solution to mining stress problem by establishing a dual-load-zone stratum structural model. Elastic foundation beam theory was used to solve the stress of overlying strata of the two load zones with superposition method, which revised the traditional calculation method of mining stress. The abnormal increase of lead abutment pressure in the mining area was explained effectively, through which the evolution law of mining stress in the case of hard rock was obtained. The results indicate that mining stress experiences a drastic change within the range of 50m ahead of the coal wall due to the collapse of main roof; under the influence of main key stratum and inferior key strata, the influence range of lead abutment pressure is extended up to approximately 120m in the working face; this remarkable increase can be attributed to the excessive length of sagging zone. Results from both the dual-load-zone model experiment and field measurement demonstrate high consistency. The model can predict the influence range of abutment pressure effectively and thus guide the safety production of mining.
Highlights
Numerous studies and explorations have been conducted on the distribution of abutment pressure in the stope by both domestic and foreign scholars [Qian, Shi and Xu (2010); Jiang (1993); Liu, Jiang and Zhu (2015); Meng (2016)]
Hu, Fan and Wang [Hu (2014)] calculated the limit equilibrium area and elastic area in the front of the stope by means of limit equilibrium theory; on this basis they analyzed the distribution of abutment pressure in the working face with large mining height and the main influence factors
The main key stratum has a remarkable influence on the distribution of abutment pressure on the working face, which is mainly manifested in the increase of peak value, the enlargement of influence range and so on [Wang (2015); Xie and Xu (2017); Zhang, Zhang, Han et al (2014); Ren and Ning (2014); Liu, Jiang, Wang et al (2011); Li, He, Yan et al (2012)]
Summary
Numerous studies and explorations have been conducted on the distribution of abutment pressure in the stope by both domestic and foreign scholars [Qian, Shi and Xu (2010); Jiang (1993); Liu, Jiang and Zhu (2015); Meng (2016)]. Two parts: Stress of primary rock and concentrated mining stress The former is constant abutment pressure while the latter is caused by the periodic failure of main roof and directly related with the range and extent of the damage on main roof. These studies illustrated the change of mining stress to some degree, but failed to consider the influence of key stratum in the overlying strata on abutment pressure. As a case study, established the calculation model of abutment pressure under the influence of main key stratum by means of key stratum theory and elastic foundation beam theory. The purpose of this research was to provide new thinking and methods for solving abutment pressure in mining area
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